Today's spread is above, the lowest is over half a century. I wrote on this a week ago and now it has just gotten lower. Here is another view:
This is a problem because it implies a very low to negative growth rate world wide. Despite the fact that we are still facing significant inflation in food, clothing, autos, fuel. This will have a massive impact on such things as pension funds who have anticipated unrealistic returns, well in excess of 7%. The State and Local Pensions are now drastically underfunded with no potential for escape. That perhaps is the next economic bubble.
Wednesday, May 30, 2012
Monday, May 28, 2012
The Wrong Question
It appears that Becker is not in any way concerned about the excessive increase in College Tuition. Posner makes a similar argument and I defer comment on that until later.
He begins his argument with:
Now this is a total nonsequitur. The increase in supply is really the result of "advertising" by Government and others to create a large pool of somewhat educated youth who can hopefully perform some useful function. For example, what good is a political science maj0or, none. Absolutely positively none. It can be said the same for an economics major, for as a "profession" they seem to all disagree with one another. Their field is more split than Greek theologians in the 4th century! Then how about a fine arts major, just where do we put them? You see it would be better to have trade schools, with electricians, plumbers, carpenters, and the like. You cannot outsource that, and there is a demand.
Now he continues:
Benefits? What benefits. In the 60s engineers were in high demand. Now they are sourced with foreign nationals, even in defense programs. The benefits are de minimis if at all. Educational costs to starting salaries have exploded. In 1965 an engineer got $8.000-$10,000 per year salary, but tuition at MIT was $1,900. That was a 4:1 to 5:1 ratio. Now the starting may be $100,000 at the very best but tuition is $60,000. Not even 2:1! And that is for a real college educated person who can be put to work creating value. Not some English major who does not know where the bathroom is to be found. What is Becker basing his conclusions on. At least I have some facts.
Now the increase in costs are due to two factors; exploding Administrative costs and exploding maintenance costs.
Becker concludes with:
First, one can monetize a property with a mortgage, if one was prudent. Namely the $100,000 debt on a $150,000 property can be sold and paid off. One cannot so readily monetize an education. Especially if it is in Liberal Arts. Who wants a History major, a Philosopher, and especially an Arts major. Students, and I suppose their families, have a duty to look into the cash flow potential of a job based upon an education. Following your dream is utter nonsense unless you accept the costs, and with Federal loan guarantees the costs are on the rest of us. So go follow your dream some where else.
So what can one say of the Becker piece.
First it has no basis in reasonable economic thought. People make decisions, or should, based upon level of investment, risk and return. Take for example chemists. The field is collapsing. We really do not need more, due to technology. But does a student understand that? In my recent experience the answer is no.
Second, if there is a benefit to society for educated and productive people, note I combined the two attributes as one, then society may thus seek to invest in that. That is yet to be proven.
Third, what of the ever expanding bubble in higher education? Is there a too big to fail mentality there as well. Does the taxpayer have a duty to keep say the University of California system afloat, why not let if collapse. If the price equals the cost then the demand will drop.
Fourth, should there be truth in advertising. We force food companies to include calories. Should we force Universities to include average lifetime earnings for each degree?
Somehow Becker seems to be justifying the unjustifiable.
The question is not what value is there in an education, but why does it cost so much! Universities have been allowed free reign, assuming someone else would take up the tab. The problem is like so many other profligate usurpers of the public trust, we the taxpayers will bear the cost. It ironically is that Quiet Generation, born before 1945, who paid their own way, then their children's and now their grandchildrens' way. The ones who are accused of getting too much Social Security and Medicare but who still work and pay into the system while taking what few pennies left to create a new generation of educated individuals. Those educated individuals may be able to then support the Baby Boomers who seem to be coming along now.
He begins his argument with:
Student loans have increased the supply of young persons who go to
college. In a competitive higher education market-which describes the
American situation where thousands of colleges compete for students- a
greater number of college students induces increases in tuition.
However, the increased supply of places for college students moderates
the increases in tuition.
Now this is a total nonsequitur. The increase in supply is really the result of "advertising" by Government and others to create a large pool of somewhat educated youth who can hopefully perform some useful function. For example, what good is a political science maj0or, none. Absolutely positively none. It can be said the same for an economics major, for as a "profession" they seem to all disagree with one another. Their field is more split than Greek theologians in the 4th century! Then how about a fine arts major, just where do we put them? You see it would be better to have trade schools, with electricians, plumbers, carpenters, and the like. You cannot outsource that, and there is a demand.
Now he continues:
Although students and their parents complain a lot about the rise in
college tuition, since the early 1980s monetary and other benefits from
college have risen even faster than tuition and other college costs. As a
result, the rate of return on college education in the United States –
benefits net of all costs- grew greatly during the past 30 years. The
increased net return to college, despite the increase in tuition,
explains why a larger, not smaller, fraction of young persons are going
to college than did prior to the sustained rise in tuition.
Benefits? What benefits. In the 60s engineers were in high demand. Now they are sourced with foreign nationals, even in defense programs. The benefits are de minimis if at all. Educational costs to starting salaries have exploded. In 1965 an engineer got $8.000-$10,000 per year salary, but tuition at MIT was $1,900. That was a 4:1 to 5:1 ratio. Now the starting may be $100,000 at the very best but tuition is $60,000. Not even 2:1! And that is for a real college educated person who can be put to work creating value. Not some English major who does not know where the bathroom is to be found. What is Becker basing his conclusions on. At least I have some facts.
Now the increase in costs are due to two factors; exploding Administrative costs and exploding maintenance costs.
Becker concludes with:
Young families with mortgages that exceed $100,000 under normal
circumstances are not considered to be in dire economic straits, even
though their homes can be taken if they fail to meet their mortgage
payments, and they are only investing in more comfortable living
arrangements. Young couples that contracted a similar level of debt when
they were students have invested in raising their earning power,
usually by a lot. So I find it difficult to comprehend why sizable
mortgages are accepted while there are political and media outcries over
comparable student loans that are based on usually highly productive
investments in human capital.
First, one can monetize a property with a mortgage, if one was prudent. Namely the $100,000 debt on a $150,000 property can be sold and paid off. One cannot so readily monetize an education. Especially if it is in Liberal Arts. Who wants a History major, a Philosopher, and especially an Arts major. Students, and I suppose their families, have a duty to look into the cash flow potential of a job based upon an education. Following your dream is utter nonsense unless you accept the costs, and with Federal loan guarantees the costs are on the rest of us. So go follow your dream some where else.
So what can one say of the Becker piece.
First it has no basis in reasonable economic thought. People make decisions, or should, based upon level of investment, risk and return. Take for example chemists. The field is collapsing. We really do not need more, due to technology. But does a student understand that? In my recent experience the answer is no.
Second, if there is a benefit to society for educated and productive people, note I combined the two attributes as one, then society may thus seek to invest in that. That is yet to be proven.
Third, what of the ever expanding bubble in higher education? Is there a too big to fail mentality there as well. Does the taxpayer have a duty to keep say the University of California system afloat, why not let if collapse. If the price equals the cost then the demand will drop.
Fourth, should there be truth in advertising. We force food companies to include calories. Should we force Universities to include average lifetime earnings for each degree?
Somehow Becker seems to be justifying the unjustifiable.
The question is not what value is there in an education, but why does it cost so much! Universities have been allowed free reign, assuming someone else would take up the tab. The problem is like so many other profligate usurpers of the public trust, we the taxpayers will bear the cost. It ironically is that Quiet Generation, born before 1945, who paid their own way, then their children's and now their grandchildrens' way. The ones who are accused of getting too much Social Security and Medicare but who still work and pay into the system while taking what few pennies left to create a new generation of educated individuals. Those educated individuals may be able to then support the Baby Boomers who seem to be coming along now.
Genomic Complexity
There has been a great deal of work on genomic complexity of cancers and especially that of multiple somatic mutations in cancers.
As Berger et al state for prostate cancer:
Similarly for melanoma the Nature discussion by Hayden states:
We also note that these mutations may or may not be related in some sequence or pathway. We would also not that for the melanoma mutations the 3-14 for non sunlight exposed and the 111 for sunlight exposed is significant and causal. However we have also argued that such might also be the case for backscatter X ray scanning as now used by the US Government to an excessive degree.
As Berger et al state for prostate cancer:
We identified a median of 3,866 putative somatic base mutations (range: 3,192–5,865) per tumor; the estimated mean mutation frequency was 0.9 per megabase. This mutation rate is similar to that observed in acute myeloid leukemia and breast cancer but 7–15 fold lower than rates reported for small cell lung cancer and melanoma17–19. The mutation rate at CpG dinucleotides was more than 10-fold higher than at all other genomic positions. A median of 20 non-synonymous base mutations per sample were called within protein-coding genes. We also identified six high-confidence coding indels (4 deletions, 2 insertions) ranging from 1 to 9 base pairs (bp) in length, including a 2bp frameshift in the tumor suppressor gene, PTEN.
Similarly for melanoma the Nature discussion by Hayden states:
The team also confirmed some findings from earlier studies
including the effect that sun exposure can have on the mutation rate of
tumour DNA. Tumours from areas of the body that are not frequently
exposed to sunlight had around 3 to 14 mutations every million base
pairs, whereas one patient who was known to have had high levels of sun
exposure had 111 mutations every million base pairs.
The relationship between sun exposure and mutation rates
adds to the evidence for the role of sun exposure in melanoma
development, says Laura Brockway-Lunardi, director of scientific
programmes for the non-profit Melanoma Research Alliance in Washington
DC, which helped to fund the work.
We also note that these mutations may or may not be related in some sequence or pathway. We would also not that for the melanoma mutations the 3-14 for non sunlight exposed and the 111 for sunlight exposed is significant and causal. However we have also argued that such might also be the case for backscatter X ray scanning as now used by the US Government to an excessive degree.
Labels:
Cancer
Wednesday, May 23, 2012
Yield Curve, May 2012
The above is the yield curve at selected dates over the past 2 years. The curve yesterday is one of the lowest ever. The drop in the 30 year is almost a factor of 2. The advantages are clearly to lower borrowing, if one can accomplish the task, but the second is the pressure downward on fixed investments and the taxing of those on fixed incomes.
The above is another way to view it. Note how low we see the long term rates. Most likely driven by European fears. I suspect we may see another Recession before the Fall.
This is the 30 year to 30 day spread, the widest one would expect. It has reached an all time low!
This is the 10 year to 90 day spread, a typical metric, also at an all time low. The faith in any recovery has disappeared.
This is the same as above but we have combined them. Note the up tick on the 90 day but the down tick on the 10 year thus shortening the spread. This does not bode well for any recovery.
The above is another way to view it. Note how low we see the long term rates. Most likely driven by European fears. I suspect we may see another Recession before the Fall.
This is the 30 year to 30 day spread, the widest one would expect. It has reached an all time low!
This is the 10 year to 90 day spread, a typical metric, also at an all time low. The faith in any recovery has disappeared.
This is the same as above but we have combined them. Note the up tick on the 90 day but the down tick on the 10 year thus shortening the spread. This does not bode well for any recovery.
Labels:
Economy,
Yield Curve
Ongoing PSA Debate
The current debate over PSA levels, testing and care continues. The NY Times has two articles yesterday on the Task Force Report.
Let me comment.
First the title was New Data on Harms of Prostate Cancer Screening. The article was written by a woman, and yes that does mean something, but the title is basically false. The screening itself does de minimis harm unless there is something done improperly. Even saturation biopsy, 20 or more cores, can be performed in a properly prepped person with de minimis morbidity. Yes there are a few infections, and yes there is hematuria, and yes there is some minor nerve damage and discomfort, but the alternative is rather terrifying. Colonoscopies have similar issues plus perforation of the colon. Is morbidity present, yes, to an overwhelming degree, in my opinion and experience, not really.
But one should read carefully the next to last paragraph:
And the law will remain in effect unless Congress overturns it. Well, is that not what the Task Force is recommending. Let me remind the reader:
1. The Task Force is mainly concerned about the morbidity resulting from biopsies. That should be a decision made between the patient and their, in this case his, physician. Informed consent. It is not in the authority realm of the Task Force to tell me what discomfort level I should tolerate. If so then most likely no one would ever go to a Dentist as a child. However some discomfort to detect and remedy a PCa is much better than death from it.
2. It is true as we have argued that PCa comes in all shapes and sizes. And further as we have repeatedly reported and written on, PCa types are not yet identifiable. Does one have an indolent or aggressive form? In addition is there a cancer stem cell here we should try and find, perhaps. But we cannot and should not assume that since some are indolent we treat all people the same. Why not treat all women with breast lesions as DIC only, I rather not think so.
In the same edition of the Times there is a long discussion regarding preventive care. They state:
Could health care costs be reined in by improving access to preventive care? It’s an idea that appeals to policy makers and many public health experts, but the evidence for it is surprisingly hard to pin down.
Is this not the same issue?
Let me comment.
First the title was New Data on Harms of Prostate Cancer Screening. The article was written by a woman, and yes that does mean something, but the title is basically false. The screening itself does de minimis harm unless there is something done improperly. Even saturation biopsy, 20 or more cores, can be performed in a properly prepped person with de minimis morbidity. Yes there are a few infections, and yes there is hematuria, and yes there is some minor nerve damage and discomfort, but the alternative is rather terrifying. Colonoscopies have similar issues plus perforation of the colon. Is morbidity present, yes, to an overwhelming degree, in my opinion and experience, not really.
But one should read carefully the next to last paragraph:
xxxxx said that some men might look at the data on risks and benefits and
decide that they still want to be tested, and nothing in the
recommendations would prevent that. He also noted that federal
legislation passed in the 1990s requires Medicare to cover the cost of
P.S.A. testing, and that law will remain in effect unless Congress
overturns it. Many insurance companies follow the lead of Medicare when
it comes to reimbursement for health coverage.
And the law will remain in effect unless Congress overturns it. Well, is that not what the Task Force is recommending. Let me remind the reader:
1. The Task Force is mainly concerned about the morbidity resulting from biopsies. That should be a decision made between the patient and their, in this case his, physician. Informed consent. It is not in the authority realm of the Task Force to tell me what discomfort level I should tolerate. If so then most likely no one would ever go to a Dentist as a child. However some discomfort to detect and remedy a PCa is much better than death from it.
2. It is true as we have argued that PCa comes in all shapes and sizes. And further as we have repeatedly reported and written on, PCa types are not yet identifiable. Does one have an indolent or aggressive form? In addition is there a cancer stem cell here we should try and find, perhaps. But we cannot and should not assume that since some are indolent we treat all people the same. Why not treat all women with breast lesions as DIC only, I rather not think so.
In the same edition of the Times there is a long discussion regarding preventive care. They state:
Could health care costs be reined in by improving access to preventive care? It’s an idea that appeals to policy makers and many public health experts, but the evidence for it is surprisingly hard to pin down.
Is this not the same issue?
Labels:
Health Care
CBO and the Economy
The CBO has just issued a report looking at the impact of continued freeze in Congress, and the impact of such a Fiscal policy.
It states:
CBO estimates that the combination of policies under current law will
reduce the federal budget deficit by $607 billion, or 4.0 percent of
gross domestic product (GDP), between fiscal years 2012 and 2013. The
resulting weakening of the economy will lower taxable incomes and raise
unemployment, generating a reduction in tax revenues and an increase in
spending on such items as unemployment insurance. With that economic
feedback incorporated, the deficit will drop by $560 billion between
fiscal years 2012 and 2013, CBO projects.
They conclude:
Well someone must do something, but I suspect we will have to wait until after the election.
It states:
They conclude:
What Might Policymakers Do Under These Circumstances?
They could address the short-term economic challenge by eliminating
or reducing the fiscal restraint scheduled to occur next year without
imposing comparable restraint in future years—but that would have
substantial economic costs over the longer run. Alternatively, they
could move rapidly to address the longer-run budgetary problem by
allowing the full measure of fiscal restraint now embodied in current
law to take effect next year—but that would have substantial economic
costs in the short run. Or, if policymakers wanted to minimize the
short-run costs of narrowing the deficit very quickly while also
minimizing the longer-run costs of allowing large deficits to persist,
they could enact a combination of policies: changes in taxes and
spending that would widen the deficit in 2013 relative to what would
occur under current law but that would reduce deficits later in the
decade relative to what would occur if current policies were extended
for a prolonged period.
Well someone must do something, but I suspect we will have to wait until after the election.
Labels:
Economy
Tuesday, May 22, 2012
Prostate Cancer Screening, The Task Force
The USPSTF has issued its dictum on PCa screening with PSA. It states:
The USPSTF recommends against PSA-based screening for prostate cancer (grade D recommendation).
This recommendation
applies to men in the general U.S. population, regardless of age. This
recommendation does not include
the use of the PSA test for surveillance after
diagnosis or treatment of prostate cancer; the use of the PSA test for
this
indication is outside the scope of the USPSTF.
It continues:
Men with screen-detected cancer can potentially fall into 1 of 3
categories: those whose cancer will result in death despite
early diagnosis and treatment, those who will
have good outcomes in the absence of screening, and those for whom early
diagnosis
and treatment improves survival. Only randomized
trials of screening allow an accurate estimate of the number of men who
fall
into the latter category. There is convincing
evidence that the number of men who avoid dying of prostate cancer
because of
screening after 10 to 14 years is, at best, very
small. Two major trials of PSA screening were considered by the USPSTF:
the
U.S. PLCO (Prostate, Lung, Colorectal, and
Ovarian) Cancer Screening Trial and the ERSPC (European Randomized Study
of Screening
for Prostate Cancer).
The U.S. trial did not
demonstrate any prostate cancer mortality reduction. The European trial
found
a reduction in prostate cancer deaths of
approximately 1 death per 1000 men screened in a subgroup of men aged 55
to 69 years.
This result was heavily influenced by the
results of 2 countries; 5 of the 7 countries reporting results did not
find a statistically
significant reduction. All-cause mortality in
the European trial was nearly identical in the screened and nonscreened
groups.
The dissenting view stated:
Prostate cancer death was reduced by 21% in the screened compared with the control group and 29%
after adjustment for noncompliance (5). The Task Force concluded that this decrease in prostate cancer–specific mortality amounted to few lives saved and did not
outweigh …
The recommendations of the USPSTF carry considerable weight with
Medicare and other third-party insurers and could affect
the health and lives of men at high risk for
life-threatening disease. We believe that elimination of reimbursement
for PSA
testing would take us back to an era when prostate
cancer was often discovered at advanced and incurable stages. At this
point,
we suggest that physicians review the evidence, follow
the continuing dialogue closely, and individualize prostate cancer
screening decisions on the basis of informed patient
preferences.
Now for our comments (see our draft book on PCa) :
1. We have discussed fatal flaws in our opinion in both studies relied upon. Simply they both used the old PSA threshold of 4 and did not include age dependency, percent free PSA and PSA velocity. In addition the European study had too great a time interval between tests.
2. No single PCa is alike. As we have been demonstrating for the past four years, the genetic makeup of PCa is complex and there are clearly certain specific markers for highly malignant PCa. By abandoning the test is throwing the baby out with the bathwater.
3. In my opinion this is a clearly age biased result, with the intent of removing care from the second highest cause of death amongst men. One wonders why!
4. Genetic makeup and family history are major drivers. PSA irregularities are one, along with PC3A testing, to ascertain PCa potential. Why eliminate it. The reason seems to be the cost of subsequent procedures, yet the Task Force argues it is the morbidity to the patient. Frankly morbidity in a competently performed procedure is less than a tooth extraction. Perhaps excess morbidity is more in the mind of the Task Force than reality.
What then is lost? We believe a great deal.
1. We are just beginning to understand the genetic makeup, just look at some of our recent postings, so that having the pool of data is indispensable. Having a genetic profile of multiple PCa would be the key to understanding the dynamics of PCa and its control.
2. What is the value of one life. If one has seen the agony of bone mets in a PCa patient, the results of DIC, and the loss of any dignity in the final days with catheter changes by a less than friendly "health care worker", the morbidity issue pales in comparison.
Hopefully we can find ways to work around this less than useful Government cost cutting "death panel" regulation. Welcome to our new world of health care!
Labels:
Cancer,
Health Care
Monday, May 21, 2012
SPOP and Prostate Cancer
SPOP is part of the Hedgehog signalling pathway[1]. The Hedgehog signalling
pathway controls amongst other factors the formation of body segments in
insects and in vertebrates the development of the neural tube, limbs and
left-right asymmetry. In adult tissues Hedgehog is responsible for homeostasis,
equilibrium between cells loss and gain while maintaining total mass and
function. With an overactive Hedgehog pathway one sees excess cell proliferation
and tumor growth[2].
We demonstrate that below:
Thus SPOP has a controlling mechanism for cell replication.
Here Hedgehog attaches to Patched and the Patched inhibition of Smothered is
eliminated allowing Smothered to start a transcription process enabling
replication.
Now upon the activation of Smothered a set of processes are
activated and one product is a protein called the zinc finger transcription
factor Gli, which when mutually supported by SPOP allows movement to the
nucleus as a transcription factor activating the DNA to transcribe[3]. We depict that below:
From Barbieri et al we have the following putative relationships:
The authors argue that SPOP is a separate and significant
marker for PCa. The pathway involved is somewhat understood and is a
transcription driven pathway initiated by Hedgehog activation and Patched
suppression with Smothered activation. From the NCI pathway databases we have a
putative requirement that SPOP is needed to activate GLI for subsequent
transcription and cell reproduction.
Specifically Barbieri et al state:
As demonstrated by a subsequent analysis of significantly
more genomes, there are only a few truly recurrent non-synonymous mutations in
PCa. The most common
recurrent non-synonymous mutation in PCa involves SPOP.
The SPOP gene encodes for the substrate-recognition component of
a Cullin3-based E3-ubiquitin ligase. Mutations
in SPOP in PCa were reported originally in two systematic
sequencing studies. We have
now identified the presence of recurrent mutations in SPOP in
6–13% of human PCas in multiple independent patient cohorts.
Recurrent missense mutations are found exclusively in the structurally defined substrate-binding cleft of SPOP, and structural analysis suggests that these mutations will inactivate SPOP function by disrupting SPOP–substrate interaction.
Further, we found that loss of SPOP function in prostate cell lines resulted in increased invasion and altered gene expression; evidence of this expression signature was identified in primary tumours harbouring SPOP mutation.
Importantly, all SPOP mutations occurred in tumours that were negative for ERG rearrangement; these tumours displayed characteristic somatic copy number aberrations. Taken together, these findings support a distinct molecular class of PCa.
Recurrent missense mutations are found exclusively in the structurally defined substrate-binding cleft of SPOP, and structural analysis suggests that these mutations will inactivate SPOP function by disrupting SPOP–substrate interaction.
Further, we found that loss of SPOP function in prostate cell lines resulted in increased invasion and altered gene expression; evidence of this expression signature was identified in primary tumours harbouring SPOP mutation.
Importantly, all SPOP mutations occurred in tumours that were negative for ERG rearrangement; these tumours displayed characteristic somatic copy number aberrations. Taken together, these findings support a distinct molecular class of PCa.
In a recent Nature Medicine article the same authors relate[4]:
Prostate cancer is the second most common cancer in men
worldwide and causes over 250,000 deaths each year. Overtreatment of indolent
disease also results in significant morbidity. Common genetic alterations in
prostate cancer include losses of NKX3.1 (8p21) and PTEN (10q23), gains of AR
(the androgen receptor gene) and fusion of ETS family transcription factor
genes with androgen-responsive promoters.
Recurrent somatic base-pair substitutions are believed to be less contributory in prostate tumorigenesis but have not been systematically analyzed in large cohorts. Here, we sequenced the exomes of 112 prostate tumor and normal tissue pairs. New recurrent mutations were identified in multiple genes, including MED12 and FOXA1. SPOP was the most frequently mutated gene, with mutations involving the SPOP substrate-binding cleft in 6–15% of tumors across multiple independent cohorts.
Prostate cancers with mutant SPOP lacked ETS family gene rearrangements and showed a distinct pattern of genomic alterations. Thus, SPOP mutations may define a new molecular subtype of prostate cancer.
Recurrent somatic base-pair substitutions are believed to be less contributory in prostate tumorigenesis but have not been systematically analyzed in large cohorts. Here, we sequenced the exomes of 112 prostate tumor and normal tissue pairs. New recurrent mutations were identified in multiple genes, including MED12 and FOXA1. SPOP was the most frequently mutated gene, with mutations involving the SPOP substrate-binding cleft in 6–15% of tumors across multiple independent cohorts.
Prostate cancers with mutant SPOP lacked ETS family gene rearrangements and showed a distinct pattern of genomic alterations. Thus, SPOP mutations may define a new molecular subtype of prostate cancer.
This just adds another gene in the mix for PCa. Namely they
authors argue that it is a different type. We would still ask the same
questions:
1. What is the issue regarding the presence or absence of a
CSC stem cell in PCa.
2. When does this mutation occur.
3. What causes the mutation.
4. SPOP is not a true kinase so what type of blocking would
be possible to mitigate the presence of a mutant.
References
1. Barbieri, C. et al, Molecular genetics of prostate cancer:
emerging appreciation of genetic complexity, Histopathology 2012, 60, 187–198.
2.
Barbieri, C., et al, Exome
Sequencing Identifies Recurrent SPOP, FOXA1 and MED12 Mutations in Prostate
Cancer, Nature Genetics (2012).
3.
Marks, F., et al, Cellular
Signal Processing, Garland (New York) 2009.
4.
Pecorino, L, Molecular
Biology of Cancer, Oxford (New York) 2008.
[1] http://pid.nci.nih.gov/search/MoleculePage?molid=203488 and http://pid.nci.nih.gov/search/search_landing.shtml?atom_id=208460,208462&what=graphic&jpg=on
and pathway at http://pid.nci.nih.gov/search/advanced_landing.shtml?what=graphic&svg=&jpg=true&xml=&biopax=&complex_uses=on&family_uses=on°ree=1&molecule=&pathway=hedgehog¯o_process=&source_id=5&evidence_code=NIL&evidence_code=IAE&evidence_code=IC&evidence_code=IDA&evidence_code=IFC&evidence_code=IGI&evidence_code=IMP&evidence_code=IOS&evidence_code=IPI&evidence_code=RCA&evidence_code=RGE&evidence_code=TAS&output-format=graphic&Submit=Go
[2]
See Marks et al p 210-212.
[3]
See Pecorino, p. 168-170.
Labels:
Cancer
Friday, May 18, 2012
Melanoma and Pathway Blocking
In a recent ASCO news release there is a report of blocking of BRAF and MEK in melanoma thus having the BRAF block the melanoma pathway and the MEK blocking the secondary squamous cell cancer pathway.
The release states:
The result is not unexpected but it does presage a broader application of multiple pathway inhibiting profiles.
The release states:
Results from an expanded Phase IB trial show that combination therapy with two investigational targeted drugs – the BRAF inhibitor dabrafenib and the MEK inhibitor trametinib – stalls cancer progression and with a lower level of skin side effects than published studies of the current standard single-agent BRAFtargeted therapy, vemurafenib (Zelboraf), have shown. The analysis included patients with advanced melanoma who had a V600 BRAF mutation and who had no previous BRAF-targeted treatment. Approximately half of all melanomas harbor a V600E mutation in the BRAF gene; in those patients, the nearby MEK pathway is also highly active. While the approval of vemurafenib last year represented a major research achievement, most patients eventually develop resistance to the drug. It is hoped that simultaneously targeting the two active pathways – BRAF and MEK – will provoke a stronger anti-cancer response and prevent, or further delay, treatment resistance.
The result is not unexpected but it does presage a broader application of multiple pathway inhibiting profiles.
Labels:
Cancer
Social Justice and Catholics
Social Justice is a movement which argues that it is the Government's responsibility to provide others with what is perceived missing to establish what is perceived by them as an equity or to use the euphemism, a level playing field, and in reality an equality of outcome. ( To better understand this position it is worth reading my book on Individualism and Neo-Progressivism)
In the NY Times today some author states:
Now the interpretation of personal duty, rather than group duty, is a matter of concern regarding the treatment of others. One could argue that the Sermon on the Mount was a call to personal duty, not a call to the Government of Rome to establish programs for the poor. The duty is individual, and individuals may group together to provide necessary services to those in need but the taxing and forced participation is questionable at best. Those who support Social Justice support a program of forced participation in satisfying needs perceived by a few but supported by the many.
In contrast the same people will force the Church to supply services that it objects to. Yet the Church would object to that force but ironically some of the same voices will press for the forced contributions under the rubric of social justice.
One wonders how one achieves what is sought for the doing of good deeds when one is forced to do so under the rubric of Social Justice. Is it the duty of Government or of the Church or of the individual.
The author continues:
No, political operatives do not walk in the front doors, in fact one would suspect if they were allowed the tax benefit would be promptly revoked, albeit it appears not to be the case in other churches.
Catholics are individuals for the most part. With the general exception of the Sophists one finds in Jesuits, the arguments, if any, are limited. Catholics in this election will not be any block. If they ever were. Rome seems to have taken the position of admonishing Governments while leaving the individual free from any duty. I frankly find this difficult to rationalize with the teachings of th first seven centuries. Yet in many ways it was a response to Socialism and Communism, the concept of Social Justice.
In the NY Times today some author states:
A broad, upbeat theme of social justice will be enough for Obama to
reach persuadable Catholics, who can interpret the message in concert
with their beliefs. The president might quote Pope John Paul II, who
once said, “Radical changes in world politics leave America with a
heightened responsibility to be, for the world, an example of a
genuinely free, democratic, just and humane society.” They must hear the
message often and at least 15 percent of the time in Spanish.
Now the interpretation of personal duty, rather than group duty, is a matter of concern regarding the treatment of others. One could argue that the Sermon on the Mount was a call to personal duty, not a call to the Government of Rome to establish programs for the poor. The duty is individual, and individuals may group together to provide necessary services to those in need but the taxing and forced participation is questionable at best. Those who support Social Justice support a program of forced participation in satisfying needs perceived by a few but supported by the many.
In contrast the same people will force the Church to supply services that it objects to. Yet the Church would object to that force but ironically some of the same voices will press for the forced contributions under the rubric of social justice.
One wonders how one achieves what is sought for the doing of good deeds when one is forced to do so under the rubric of Social Justice. Is it the duty of Government or of the Church or of the individual.
The author continues:
What would a Catholic voter outreach program look like? The Roman
Catholic Church doesn’t exactly let political operatives walk in the
front door and set up shop, but there are several progressive Catholic
organizations — Catholics United, Catholics in Alliance, Catholic
Democrats — that the campaign could engage first to build a volunteer
corps. Within each district office, the campaign could identify Catholic
precinct captains to recruit Catholic door-knockers to reach out to
their friends from church. Then there’s advertising. It would be more
difficult to construct this architecture from scratch, but however it’s
done, it’s a must: a positive social justice message could be what tips
the balance toward re-election for the president.
No, political operatives do not walk in the front doors, in fact one would suspect if they were allowed the tax benefit would be promptly revoked, albeit it appears not to be the case in other churches.
Catholics are individuals for the most part. With the general exception of the Sophists one finds in Jesuits, the arguments, if any, are limited. Catholics in this election will not be any block. If they ever were. Rome seems to have taken the position of admonishing Governments while leaving the individual free from any duty. I frankly find this difficult to rationalize with the teachings of th first seven centuries. Yet in many ways it was a response to Socialism and Communism, the concept of Social Justice.
Labels:
Commentary
Facebook and the Value Proposition
When looking at any business opportunity one looks at how value is created and how the company can monetize this value. Value is relative to the user. For example, Microsoft had substantial value creating capacity, and yes it cost to attain it. It was the word processor, spread sheet, and to some degree the operating system. Google had substantial value. It allowed access to information and it created and environment to share it and to monetize it via advertising.
I was a very early Facebook user at MIT, students drove the use. I have not used it for two years. It has no value and in fact it has a negative value. Why? Because it allows somewhat crazy comments from those to whom I was linked to create my profile. It had negative value. It also lacked privacy from my perspective. Thus I left.
So when looking at Facebook I see another AOL. And why AOL, because when in the mid 1990s while teaching at Columbia Business School I did a case on AOL and stated that in my analysis at the time it was at best declining in value. That was before the Time Warner acquisition. I see possibly the same here with Facebook. Yes it is a "social media" and yes it facilitates such communications. But is it of singular value to a person, a company? Time will tell.
I was a very early Facebook user at MIT, students drove the use. I have not used it for two years. It has no value and in fact it has a negative value. Why? Because it allows somewhat crazy comments from those to whom I was linked to create my profile. It had negative value. It also lacked privacy from my perspective. Thus I left.
So when looking at Facebook I see another AOL. And why AOL, because when in the mid 1990s while teaching at Columbia Business School I did a case on AOL and stated that in my analysis at the time it was at best declining in value. That was before the Time Warner acquisition. I see possibly the same here with Facebook. Yes it is a "social media" and yes it facilitates such communications. But is it of singular value to a person, a company? Time will tell.
Labels:
Commentary
Cancer Models:Prediction and Control
We will now consider what are the essential elements for
modeling cancers. The first step is to re-establish the goals of a model and
then its structure. Finally we will lead into the interrelationship between a
model and the data which is used to justify it.This work is detailed in a recent White Paper.
Many authors have developed models concerning pathways and
also cancer. The books by Klipp et al and that of Szlassi et al are excellent
overviews of the area with significant detail. The Klipp et al book is a truly
superb discussion regarding pathways and modeling alternatives. The books by
Bellomo et al and Wang are directed specifically at cancer modeling but
unfortunately they lack adequate pathway dynamics to be of substantial use. Yet
they are the only books available within the focused area.
At the core, we want a model which reflects the following
qualities:
1. Based Upon Reality: The model must at its core be based
upon the known reality. It must conform with what we currently know and
understand. Namely it must reflect in its core the elements which we consider
critical and the temporal and spatial dynamics of those elements. The model
must be based upon a tempero-spatial system of measurable quantities ;linked in
some kinetic manner using reasonably well understood processes.
2. Predictability: Any modeling must, if it is to have any
credibility, have the ability to predict, to say what will happen, and then to
have that prediction validated. Although the ability may be statistical in
nature the statistical confidence must be justifiable. We know all too well
that many things are correlated, yet not causal, and not predictable.
3. Measurable: One must be able to measure and then predict
the quantities which make up the model. Many of the modeling systems include
proteins but they react in some zero-one format. We know in reality that we
have concentrations, or better yet specific numbers of proteins, produced in a
cell. Yet we cannot yet measure the number of each of these proteins. We all
too often can at best measure their presence or absence. However, is it not the
case that it is the excess or the low density of some set of proteins which
shift reactions, and that reactions are often concentration dependent.
4. Modellable: We want a system which can be modeled. It
must reflect the measurable quantities in space and time and the
tempero-spatial dynamics of them, using techniques that we can then use for
prediction and validation.
In this paper we examine and analyze several models of
cancer. Specifically we look at intracellular, extracellular and full body
models. We attempt to establish a linkage between all of them. Many researchers
have looked at the gene level, the pathway level and the gross flow of cancer
cell level, namely whole body. Connecting them has been complex to say the least.
But herein we look at the pathway level and a whole body
level and demonstrate the nexus, physically, and from this we argue that one
can construct both prognostic tools as well as methodologies to deal with
metastasis.
The following graphic lays out the flow of development and
its implications as we detail them herein.
The key question we ask is just what is it we are modeling
in cancer cell dynamics. Let us consider some options:
This type of model focuses on the genes, and their behavior.
It is basically one where we examine the gene type and its product.
This type of model falls in several subclasses. All begin
with protein pathways and the “dynamics” of such pathways. But we have two
major subclasses; protein measures and temporal measures. By the former we mean
that we can look at the proteins as being on or off, there or not there, or at
the other extreme looking at the total number of proteins of a specific type
generated and present at a specific time. By the latter, namely the temporal
state, we can look at the proteins in some static sense, namely there or not
there at some average snapshot instance, or we can look at the details over
time, the detailed dynamics. In all cases we look at the intracellular dynamics
only.
Let us consider the two approaches.
i. On-Off: In this approach the intracellular relationships
are depicted as activators or inhibitors, namely if present they allow or block
an element in a pathway. PTEN is a typical example, if present it blocks Akt,
if absent it allows Akt to proceed and enter mitosis. p53 is another example
for if present we have apoptosis and if absent we fail to have apoptosis. These
are simplistic views. This is a highly simplistic view but it does align with
the understanding available say with limited microarray techniques. This is an
example of the data collection defining what the model is or should be.
ii. Density: This is a more complex model and it does
reflect what we would see as reality. The underlying assumptions here are:
a. Genes are continually producing proteins via
transcription and translation.
b. Transcription and translation are affected at most by
proteins from other genes acting as repressors or activators. There are no
other elements affecting the process of transcription and translation. Not that
this precludes any miRNA, methylation, or other secondary factors. We shall
consider them later. In fact they may often be the controlling factors.
c. The kinetics of protein production can be determined.
Namely we know the rate at which transcription and translation occur in a
normal cell or even in a variant. That is we know that the production rate of
proteins can be given by a typical creation differential equation.
Here we have production rates dependent on the concentration
of other proteins. The processes related to consumption are not totally
understood (see Martinez-Vincente et al). We understand cell growth, as
distinct from mitotic duplication, but the growth of a cell is merely the
expansion of what was already in the cell when at the end of its mitotic
creation. In contrast, we understand apoptosis, the total destruction of the
cell, we also understand that certain proteins flow outside the cell or may be
used as cell surface receptors, but the consumption of these is not fully
understood. Yet we can postulate a similar destruction differential equation.
This is based upon the work of Martinez-Vincente et al which
states[1]:
All intracellular proteins undergo continuous synthesis
and degradation. This constant protein turnover, among other functions, helps
reduce, to a minimum, the time a particular protein is exposed to the hazardous
cellular environment, and consequently, the probability of being damaged or
altered. At a first sight, this constant renewal of cellular components before
they lose functionality may appear a tremendous waste of cellular resources.
However, it is well justified considering the detrimental
consequences that the accumulation of damaged intracellular components has on
cell function and survival. Furthermore, protein degradation rather than mere
destruction is indeed a recycling process, as the constituent amino acids of
the degraded protein are reutilized for the synthesis of new proteins.
The rates at which different proteins are synthesized and
degraded inside cells are different and can change in response to different
stimuli or under different conditions. This balance between protein synthesis
and degradation also allows cells to rapidly modify intracellular levels of
proteins to adapt to changes in the extracellular environment. Proper protein
degradation is also essential for cell survival under conditions resulting in
extensive cellular damage. In fact, activation of the intracellular proteolytic
systems occurs frequently as part of the cellular response to stress. In this
role as ‘quality control’ systems, the proteolytic systems are assisted by
molecular chaperones, which ultimately determine the fate of the
damaged/unfolded protein.
Damaged proteins are first recognized by molecular
chaperones, which facilitate protein refolding/repairing. If the damage is too
extensive, or under conditions unfavorable for protein repair, damaged proteins
are targeted for degradation. Protein degradation is also essential during
major cellular remodeling (i.e. embryogenesis, morphogenesis, cell
differentiation), and as a defensive mechanism against harmful agents.
We have also discussed this process with regards to the
function of ubiquitin, which marks proteins for elimination. As Goldberg states[2]:
Proteins within cells are continually being degraded to
amino acids and replaced by newly synthesized proteins. This process is highly
selective and precisely regulated1,
and individual proteins are destroyed at widely different rates, with
half-lives ranging from several minutes to many days. In eukaryotic cells, most
proteins destined for degradation are labelled first by ubiquitin in an energy requiring
process and then digested to small peptides by the large proteolytic complex,
the 26S proteasome.
Indicative of the complexity and importance of this
system is the large number of gene products (perhaps a thousand) that function
in the degradation of different proteins in mammalian cells. In the past
decade, there has been an explosion of interest in the ubiquitin–proteasome
pathway, due largely to the general recognition of its importance in the
regulation of cell division, gene expression and other key processes1. However, the cell’s degradative machinery must
have evolved initially to serve a more fundamental homeostatic function — to
serve as a quality-control system that rapidly eliminates misfolded or damaged
proteins whose accumulation would interfere with normal cell function and
viability.
Also we refer to the recent review work of Ciechanover which
details the evolution of this understanding[3].
In contrast the proteins are consumed and thus the negative
sign. In toto we have a combined equation as a total balance of proteins. This
assumes we have a production mechanism for each of the proteins, namely their
genes and the activators and repressors as required.
d. Pathway Dynamics must be meaningful. Let us consider the
pathway as shown below. This is a typical melanoma pathway we have shown
before.
Now let us consider PTEN blocking BRAF and Akt. Now
physically it is one molecule of PTEN needed for each molecule of BRAF and
PI3K. But what if we have the following: n(PTEN)n(PI3K).
Here we have PTEN blocking some but not all the BRAF and
PTEN blocking all the PI3K. At least at time t. Do we have an internal
mechanism which then produces even more PTEN? One must see here that we are
looking at the actual numbers of PTEN, real numbers reflecting the production
and destruction rates. We know for example that if we have a mutated BRAF then
no matter how much PTEN we have an unregulated pathway.
Now it is also important to note that this “model” and
approach is distinct in ways from classic kinetics, since the classic model
assume a large volume and concentrations in determining kinetic reaction rates
of catalytic processes. Here we assume a protein binds one on one with another
protein to facilitate a pathway.
Thus knowing the dynamics of individual proteins, and
knowing the pathways of the proteins, namely the temporary adhesion of a
protein, we can determine several factors:
1.
The number of free proteins
by type
2.
The pathways activated or
blocked
3.
The resultant cellular
dynamics based on activated pathways.
It should be noted that we see pathways being turned on and
off as we produce and destroy proteins. There is a dynamic process ongoing and
it all depends on what would be a stasis level of proteins by type. The
question is; are cells in stasis or are they in a continual mode of regaining a
temporary stasis?
This also begs the question, that if as we have argued, that
cancer is a loss of stasis due to pathway malfunction, then can this be a
process of instability in the course of a normal cell? Namely is there in the
dynamics of cell protein counts, unstable oscillator type modes resulting in
uncontrolled mitotic behavior. Namely can a cell get locked into an unstable
state and start reproducing itself in that state, namely an otherwise normal
cell.
e. Total intracellular dynamics can be modeled yet the
underlying processes are still not understood and the required measurements are
yet to be determined.
Here we look at the intercellular dynamics as well, not just
as a stand-alone model. By this methodology we look at intercellular
communications by ligand binding and the resulting activation of the
intracellular pathways. We must consider both the intercellular signalling
between like cells but also between unlike, such a white cells perhaps as
growth factor inhibitors and the like. We also then must consider the
spatiodynamics, namely the “movement” of the cells, or in effect the lack of
fixedness or specificity of function. This becomes a quite complex problem.
There are two functions we examine here:
a. Intercellular binding or adhesion: E cadherin is one
example that we see in melanocytes. Pathway breakdown may result in the
malfunctioning of E cadherin.
The above demonstrated E cadherin in melanocyte-keratinocyte
localization. The bonds are strong and this stabilizes the melanocyte in the
basal layer. If however the E cadherin is compromised then the bond is broken,
or materially weakened, and the melanocyte starts to wander. Movement for
example above the bottom of the basal layer and upwards is pathognomonic of
melanoma in situ. Wandering downward to the dermis becomes a melanoma. Thus the
pathways activating E cadherin production is one pathway essential in the
inter-cellular dynamics.
b. Ligand production and receptor production: Here we have
cells producing ligands, proteins which venture out of the cell and become
signalling elements in the intercellular world. We have the receptor production
as well, where we have on the surface of cells, various receptors, also
composed of cell generated proteins, which allow for binding sites of the
ligands and result in pathway activation of some type. For example various
Growth Factors, GF proteins, find their way to receptors, which in turn
activate the pathways. Wnt is an example of one of these ligands which we have
shown above.
It can also be argued that as ligands are produced and as
the “flow” throughout the intercellular matrix, we can obtain effects similar
to those in the Turing tessellation models. Namely a single ligand may be
present everywhere but density of ligands may vary in a somewhat complex but
determinable manner, namely is a wavelike fashion.
This is akin to the Turing model used in patterning of
plants and animals[4].
Namely the concentration of a ligand, and in turn its effect, may be controlled
by
In this case we would want a model which reflects the total
body spatiotemporal dynamics This type of models is an ideal which may or may
not be achievable. In a simple sense it is akin to diffusion dynamics, viewing
the cancer cells as one type of particle and the remaining body cells as
another type. The cancer cells have intercellular characteristics specific to
cancer and the body cells have functionally specific characteristics. Thus we
could ask questions regarding the “diffusion” of cancer cells from a local
point to distant points based upon the media in between. The “rate” of such
diffusion could be dependent upon the local cells and their ability for example
to nourish the cancer cells as well. In this model we could define an average
concentration of cancer cells at some position x and time t and we would have
some dynamic process as well.
This is a diffusion like equation and is a whole body
equation. Perhaps knowing what the rate of diffusion is on a cell by cell basis
may allow one to determine the most likely diffusion path for the malignancy,
and in turn direct treatment as well.
This is of course pure speculation since there has been to
my knowledge any study in this area. Except one could imagine a system akin to
PET scans and the like which would use as input the surface markers from a
malignancy and then the body diffusion rates to plot out in space and time the
most likely flow of malignant cells and thus plan out treatment strategies.
Although this model is speculative we shall return again to it in a final
review of such models since it does present a powerful alternative.
This concept of total cellular dynamics is in
contradistinction to the intercellular transport. In the total cellular
dynamics model we regard the model as one considering the flow of altered cells
across an existing body of stable differentiated cells.
We may then ask, what factors drive cancer cells to what
locations? One may putatively state that cancer cells will follow the path of
least resistance and/or will proceed along “flow lines” consistent with what
propagation dynamics they may be influenced by.
The concept of a model of Total Cellular Dynamics is
somewhat innovative. It focuses on the movement of the cancer cells throughout
the body. We will consider three possible possibilities:
1. No Stem Cells
2. Stem Cells but Fixed at Initial Location
3. Stem Cells which are mobile.
In Case 1 all malignant cells are clones of each other at
least at the start. As the malignant cells continue through mitosis additional
mutations are likely so that after a broad set of mitotic divisions we have a
somewhat heterogeneous set of malignant cells, some more aggressive than
others. As with most such cancer cells they also produce ligand growth factors
which stimulate each other and result in the cascade of unlimited growth and
duplication.
In Case 2 we assume that there was a single cell which
mutated and that this becomes the CSC. The CSC replicates producing one CSC for
self-replication and TICs which migrate. We assume that the CSC may from time
to time actually double, but not at the mitosis rate of the base. Furthermore
we assume the CSC sends out growth factors, GF, to the TICs. The GF flow
outward in a wave like manner from the somewhat position stabilized CSCs to the
TICs which are mobile and both diffuse and flow throughout the body. The GF
must find the TICs which become a distant metastasis.
In Case 3 in contrast to Case 2, we assume mobile CSC and
thus the CSCs also flow according to some set of rules.
Now depending on the case we assume we can model the flow of
cancer cells according to some simple dynamic distributed models[5]. Thus we could have[6] a partial differential
equation of the type found in McGarty (see White Paper).
This provides diffusion, flow, and rate elements. The rate
term, the F term, is a rate of change in time at a certain location and time
specific. It is the duplication rate at that specific location due to the
normal mitotic change. The last term may be both pathway and environment
driven.
Now this description has certain physical realities.
Here above we describe the three factors in terms of their
effects and their causes. The three elements of the equation; diffusion, flow,
and growth, are the three ways in which cancer cells move. We can summarize
these as below:
Factor
|
Diffusion
|
Flow
|
Growth
|
Physical Effect
|
Cancer cells begin to diffuse
due to concentration effects.
|
Cancer cells are “forced” to
move by a flow mechanism driven them in a direction along flow lines.
|
Cancer cells begin to go through
mitosis and cell growth.
|
Genetic Driver
|
Movement is due to the loss of location
restrictors such as E cadherin found in melanocytes and restricting their
movement.
|
Flow lines may be developed by means of
metabolic needs of the cell in search of the nutrients required for growth.
This may be a combination of angiogenesis as well as a Warburg like effect.
|
Growth factor ligands attach to the surface
of the cell. Flow of such ligands and their production may be influenced by a
Turing flow effect thus accounting for complexity of location of growth.
|
Impact
|
Slow migration in local areas.
|
Cells have lost functionality
and move to maximize their nutrition input to facilitate growth.
|
Cancer cells may find optimal
areas for proliferation based upon factor related to ligand density.
|
Now consider the following graphic as a human body,
We have a D, E, F, for each gross portion of the body. We
also have a model as specifically below in the Table:
Organ
|
D
Diffusion
|
E
Flow
|
F
Production
|
Epidermis
|
0.5
|
0.01
|
0.7
|
Dermis
|
0.4
|
0.02
|
0.5
|
Cutis
|
0.3
|
0.05
|
0.2
|
Blood
|
5.0
|
0.5
|
0.01
|
Brain
|
0.1
|
0.01
|
0.2
|
Liver
|
2.0
|
0.2
|
0.3
|
Lung
|
3.0
|
0.3
|
0.4
|
Kidney
|
1.5
|
0.4
|
0.5
|
Bone
|
2.5
|
0.5
|
1.0
|
The above numbers are purely speculative. But if we can
ascertain them then we get a solution of p(x,t) in time. Note that here we have
a two dimensional space. Thus we have the above constants applying only to this
artifactually spatial model. Distance is measured in terms of movement across
the interfaces. For simplicity we assume that all other space is impenetrable
by any means. This we have production, flow and diffusion in each area.
Note that in the above we have laid out the x and y
coordinates such that we have blood flow in the center, namely the metastasis
flows via blood, and then enters organs as shown. The “location” of the organs
are distances. Note also the origin of the malignancy is at (0,0).
Now we can relate the constants to the pathway distortions
which are part of the malignancy as well.
The question is how do we determine these constants so that
we may verify the model. Let us assume we can do so via examination of prior
malignancy, not an obvious task but one we shall demonstrate. One must be
cautious also to include in the determination pathway factors for each
malignancy and its state and stage. Thus the three constants will be highly
dependent upon the specific genetic makeup of the initial malignancy.
Turing Tessellation
In 1952 Alan Turing, in the last year and a half of his
life, was focusing on biological models and moving away from his seminal
efforts in encryption and computers. It was Turing who in the Second World War
managed to break many of the German codes on Ultra and who also created the
paradigm for computers which we use today. In his last efforts before his
untimely suicide Turing looked at the problem of patterning in plants and
animals. This was done at the same time Watson and Crick were working on the
gene and DNA. Turing had no detailed model to work with, he had no gene, and he
had just a gestalt, if you will, to model this issue. Today we have the details
of the model to fill in the gaps in the Turing model.
The Turing model was quite simple. It stated that there was
some chemical, and a concentration of that chemical, call it C, which was the
determinant of a color. Consider the case of a zebra and its hair. If C were
above a certain level the hair was black and if below that level the hair was
white. As Turing states in the abstract
of the paper:
"It is suggested that a system of chemical
substances, called morphogens, reacting together and diffusing through a
tissue, is adequate to account for the main phenomena of morphogenesis. Such a
system, although it may originally be quite homogeneous, may later develop a
pattern or structure due to an instability of the homogeneous equilibrium,
which is triggered off by random disturbances. Such reaction-diffusion systems
are considered in some detail in the case of an isolated ring of cells, a
mathematically convenient, though biologically unusual system.
The investigation is chiefly concerned with the onset of
instability. It is found that there are six essentially different forms which
this may take. In the most interesting form stationary waves appear on the
ring. It is suggested that this might account, for instance, for the tentacle
patterns on Hydra and for whorled
leaves. A system of reactions and diffusion on a sphere is also considered. Such
a system appears to account for gastrulation. Another reaction system in two dimensions
gives rise to patterns reminiscent of dappling. It is also suggested that
stationary waves in two dimensions could account for the phenomena of
phyllotaxis.
The purpose of this paper is to discuss a possible
mechanism by which the genes of a zygote may determine the anatomical structure
of the resulting organism. The theory does not make any new hypotheses; it
merely suggests that certain well-known physical laws are sufficient to account
for many of the facts. The full understanding of the paper requires a good
knowledge of mathematics, some biology, and some elementary chemistry. Since
readers cannot be expected to be experts in all of these subjects, a number of
elementary facts are explained, which can be found in text-books, but whose
omission would make the paper difficult reading."
Now, Turing reasoned that this chemical, what he called the
morphogen, could be generated and could flow out to other cells and in from
other cells. Thus focusing on one cell he could create a model across space and
time to lay out the concentration of this chemical. He simply postulated that
the rate of change of this chemical in time was equal to two factors; first the
use of the chemical in the cell, such as a catalyst in a reaction or even part
of the reaction, and second, the flow in or out of the cell. The following
equation is a statement of Turing's observation.
It allows one to solve for a concentration, C, as a function of time
and space. It requires two things. First is the diffusion coefficient to and
from cells and second the functional relationship which shows how the chemical
is used within a cell.
The question now is how does one link the coefficients in
the models. For example if we believe that diffusion D depends on E cadherin
concentration, namely as E cadherin decreases then D increases we may postulate
a simple linear relationship between diffusion constants and protein
concentrations, where the constants are to be determined. We know that the more
E cadherin the stickier is the cell and the less diffusion that occurs. Thus
the above is at the least a first order approximation. In a similar manner we
can relate F to PTEN and p53.
This is merely suppositional. But we do know the following:
1. The genes which are expressed for adhesion and
replication are known.
2. We know the pathways for these genes
3. We know the intracellular models controlling these genes.
4. We know that functionally an excess or paucity of a gene
has a certain effect.
5. We know that in general in small amounts the world is
linear.
6. We know that we can use regression techniques based upon
collected data to determine coefficients in a general sense.
Thus we have a fundamental basis to express the relationships
for all gross constants in terms of linearized versions of the protein
concentrations.
Now we have related intracellular concentrations, which
themselves may be temporally and spatially dependent, to the total parameter
values for the flow of cells throughout the body. We may also want to relate
these to organ specific parameters as well.
Thus what we have achieved is as follows:
1. Model relating intracellular and whole body.
2. Methodology to determine the constants.
3. Methodology to go from patient data to prognostic data.
4. Methodologies to establish possible treatment
methodologies. Namely what gene controls will result in what whole body
reactions.
We can now summarize this models we have considered. First
we should emphasize that for the most part those working in the field have
developed pathway models which exhibit a non-temporal mode, it is some steady
state model, and the model assumes a protein to protein connection, as if there
were a single protein molecule produced and that the interacting proteins were
there or not. Part of the simplicity of the models is determined by the limits
of what can be measured. We have herein attempted not to limit the results by
what can be accomplished currently but has extended the model to levels which
assist in a fuller representation of reality. However even here we may very be
falling short.
For we have deliberately neglected such things as miRNA,
methylation, and the stem cell paradigm just to name a few.
We combine all four methods in a graphic below. We summarize
the key differences and differentiators. Currently most of the analytical
models focus on pathways. This can generally be supported by means of microarray
technology and even rough estimates of relative concentrations may be inferred
by such an approach.
The risks we see even in the above models is the absence of
exogenous epigenetic factors and the inclusion of a stem cell model. The latter
issue is one of major concern. For example if we have true cancer stem cells,
CSC, then we have a proliferation of differing cell types. The use of
microarrays is for the most part and averaging methodology, not a cell by cell
methodology. If we collect cells from say a melanoma tumor. how much of that is
a CSC and how much a TIC. And frankly should we identify CSCs only and perform
our analysis on those cells alone.
[3]
Ciechanover , A, Intracellular Protein Degradation: From a Vague Idea through
the Lysosome and the Ubiquitin-Proteasome System and onto Human Diseases and
Drug Targeting, Rambam Maimonides Medical Journal, January 2012, Volume 3,
Issue 1
[4] Turing, A., The Chemical Basis of Morphogenesis,
Phil Trans Royal Soc London B337 pp 37-72, 19459.
[5] See Andersen p 277 of Bellomo et al for an variant on
what we are proposing here. The Andersen model is somewhat similar but lacks
the detail we present herein. Also there is in the same volume a paper by
Pepper and Lolas focusing on the dynamics of the lymphatic cancer system, p
255. Bellomo, N., et al, Selected Topics
in Cancer Modeling, Birkhauser (Boston) 2008.
[6] McGarty, T., Stochastic Systems and State Estimation, Wiley
(New York) 1974.
1. Szallasi, Z. System Modeling in Cellular Biology: From
Concepts to Nuts and Bolts. MIT Press (Cambridge) 2006.
1. Klipp, E., et al, Systems
Biology, Wiley (Weinheim, Germany) 2009.
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