Tag Archives: Medicine

May27

Learning From Research – The Discussion

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Learning From Research – The Discussion

It’s been a while, and I’ve had a lot of stuff going on both in my life and in my mind, but I’m determined to finish this thing. Previous posts:

Part 1
Part 2

This is the section in which everything that was talked about before is kind of recapped and explained and, well, justified. I approached this in a much simpler format, because that’s really all it needs. My comments are bolded.

DISCUSSION

It was first demonstrated here that the fidelity of replicating methylation patterns of CGIs in the promoter regions is significantly higher than that of CGIs outside the promoter regions. (CGIs in promoter regions replicate themselves more accurately than the ones outside of promoter regions.) It was also demonstrated here that methylated genomic regions show much higher fidelity than unmethylated genomic regions. (If the genes are methylated, they tend to stay methylated, if they’re unmethylated, they can become methylated.) These showed that maintenance methylation of hemimethylated CpG sites into fully methylated CpG sites at DNA replication was highly reliable, while unmethylated CpG sites tended to be methylated by de novo methylation. (Methylation sticks.) It is well-known that exogenous DNA is exposed to a de novo methylation pressure (Doerfler et al. 2001; Bird 2002), and a similar methylation pressure seems to be working on the endogenous DNA. (Unmethylated sites are vulnerable to methylation from outside sources.) To maintain the unmethylated status of CGIs, protection mechanisms from the de novo methylation pressure seem to be necessary. (Unmethylated CGIs need something that protects them from methlyation or they’re vulnerable to it.) Since the MPERs were significantly lower in CGIs in the promoter regions than in CGIs outside the promoter regions, the presence of a protection mechanism(s) specific to the promoter regions, in addition to a mechanism(s) common to all CGIs, was indicated. (Promoter region CGIs probably have stronger protection against methylation of unmethylated regions, because they resist methylation better than non-promoter-region CGIs do.) Although the details of the mechanisms are still unknown, binding of transcriptional factors, such as Sp1, has been indicated as a promoter-specific mechanism (Han et al. 2001). (Hint, hint – this is something someone might want to look into, guys, ‘cuz our grant has been spent! Heh.)

The differential fidelities in replicating methylation patterns of CGIs in the promoter regions and those outside indicated that aberrant methylation of CGIs would occur at different rates depending upon their locations. This will be important when tumors are analyzed for the CGI methylator phenotype (CIMP), which are considered to be caused by molecular defects that allow accumulation of aberrant CGI methylations (Toyota et al. 1999). The differential fidelities shown here suggest that there are two types of CIMP, one due to a defect(s) in the protection mechanisms common to all CGIs and the other due to a defect(s) in the protection mechanisms specific to CGIs in the promoter regions. Actually, a correlation between the CIMP and the diffuse-type histology was clearly observed in gastric cancers when CGIs in the promoter regions were used for CIMP analysis (Kaneda et al. 2002b), while it was unclear when CGIs outside the promoter regions were used. (This will help us do more research that will help with cancer prediction/prevention/treatment, in case you don’t think that these findings have a worthwhile purpose of their own. When in doubt, reference cancer. For people with maybe a little less vision or curiosity. Just sayin’.)

In order for an impaired fidelity in maintaining a methylation pattern to exert any biological effect, methylation statuses of multiple CpG sites in a CGI must be altered. (One change at a single location isn’t going to make a big difference.) A significant increase of MPERs would be necessary for this, and quantitative analysis of MPERs in cells with suspected increase of MPERs is necessary. (We don’t know how many besides “more than one,” so another study would be required.) DMR of the H19 gene had a polymorphism at nt. 391 (nt. 8217; GenBank accession no.AF125183), and this served to distinguish the two alleles clearly. (This location was where we could best see what happened.) The G-allele was methylated in all of the six cultures, and the T-allele was unmethylated. The methylation patterns of the T-alleles were similar in HMEC11 and HMEC15, but were essentially variable among the six cultures. This indicated that, although the original cells in HMEC11 and HMEC15 might have had a common ancestral cell, methylation patterns in a tissue alter significantly during a human life span. (Methylation may change because of time, not necessarily because something came in and methylated stuff. No pointing at a specific environmental influence like a chemical or somesuch. Just demonstrating that it happened, and where and why it would be more or less likely to happen.)

Future clarification of what protection mechanisms are involved and how they are impaired in various diseases will contribute to understanding of aging (Ahuja et al. 1998; Issa et al. 2001) and various pathological conditions. (This is a single step in a huge process, but it puts us on a track to learning more than what we know now.)

Apr20

Science Education – How I Would Do It.

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Science Education – How I Would Do It.


Of course, this is assuming that the world was a sensible place and I was in charge of all the important decision-making. Heh.

Over time, I’ve come to realize that a lot of the things I was taught in school didn’t stick because they weren’t interesting. They weren’t interesting because they were unrelated to my life, and I couldn’t see how they could possibly be important to me. I memorized things for tests, and I did a darn good job of it, good grades, good standardized test scores, but only because I had to, not because I wanted to.

As I got older some of it came back – and it stuck better because I had context to put it in. Before kids and before antidepressants, I read a lot of romance novels for escape (I know. . .I’m not proud, but I had an excuse.) Soon I discovered that there was a sub-genre of Historical Fiction – and some of these authors were real history buffs who included a lot of factual information. In the context of a story, with characters and plots that engaged me, I was finally learning something about history, which had bored me to tears in High School.

Later, I started reading some of the books and papers that had been assigned back then. . .suddenly they were interesting and made sense – because I now had a context for them. The context continued to expand, and more information became part of what I knew.

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For me, possibly moreso than for many people, context is essential. My ADHD mental filing system demands context and associations not only for learning, but for retrieving that learning. So when I teach people what I know, I teach it in context. I learn a lot by making mistakes, so I teach “do it this way because this other way doesn’t work,” and “we do it this way because otherwise we break this piece and the whole thing is ruined.” I teach “This part seems boring, but here are all the cool things we can do with it later.”

I also learned a lot from raising my own kids and volunteering in their schools, helping all kinds of other kids learn. You need to be able to express a single piece of information many different ways in order to get different kids to understand it. As a volunteer, I was able to sit with individual children and small groups. The kids who didn’t understand things when they were taught the same way to all 30-something students would get it if I spent some time with them and figured out what their individual contexts were.

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Fast forward to the mid 90s – I started antidepressants, and then I discovered that my ADHD had not actually gone away as the experts had told my parents it would, and as my parents told me it had. Now I had a reason to learn about the brain, starting with disorders and injuries, and what they taught us about the functions of various structures. That gave me a context to learn about brain development and genetics. This led to investigating epigenetics. Along the way, it also tied in to reading medical and science blogs and books, and any time a piece of knowledge stuck to something that was relevant to something I already knew, it also became relevant.

So why do you want to listen to someone who doesn’t have a degree in science or medicine when it comes to science or medicine? Because of the way I’m learning it. That whole “Translating Science into English” thing I mentioned a few posts back. Scientists have their own language, and it’s important that they do so they speak with clarity and precision. But if you don’t have the context that they do, it’s hard to understand – and easy to misinterpret. I didn’t learn this in the linear fashion that they did.

If you were to teach me vocabulary and facts and mechanisms, I’d remember it just as well as I did in high school. But give me a study of something that relates to something that interests me, and I will look up all those words and facts and mechanisms, and they’ll make sense because they’re part of something else. They have more meaning when they’re in context.

The other thing I learned came from watching scientists argue with one another. While they’re not always polite, they always present evidence. Most of them are critical thinkers, when someone says something that is questionable, they will (sometimes very methodically and in great detail) explain the flaws in the reasoning. Following along with this taught me the scientific method and why it’s important, how to evaluate how robust the data is by looking at the size of the study, the quality of the blinding, the strength of the variables and controls, how well it integrates existing evidence (and how strong that evidence is) and, most importantly, no matter how good a study may be, it’s never PROOF. It also doesn’t prove other things that weren’t part of the study. It’s also probably not a major breakthrough.

I learned about p-values, journal impact factors, the good and bad of peer review, the pros and cons of open access. I learned that not all “evidence” is actually evidence.

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The problem that many, many scientists have, though, is that they forget what it’s like to not know this. Sometimes they present what they know in a way that is off-putting to laypeople. Sometimes they present a press-release version of their findings, breathless with excitement and full of hyperbole, and that’s even worse. (That’s what we have The Daily Mail and Huffington Post for. Let them do their job.)

So if I were a science teacher, or I were designing a science education program, I’d throw out teaching the basics as freestanding facts. Get rid of the rote learning. Give the students just enough information to dive into a challenge and figure out the rest. Give the kindergarteners a bowl of cream and some food coloring and dish soap – let them play and then tell them how it works. Let the older kids listen to each others’ heartbeats, check each others’ blood pressure, draw pictures of hearts and veins and arteries, and use that to introduce the circulatory system. Make everything part of an experiment that related directly to them so that it was important. Let them figure out what’s correct and what’s incorrect as much as you can on their own by giving them questions as much as answers. Make the science interesting and integrate critical thinking into the lessons, and get them excited. This will be good for them, and good for society, because they’ll question everything – and come up with their answers based on what evidence is best supported.

Apr12

Epigenetics – I do not think that word means what you think it does.

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Epigenetics – I do not think that word means what you think it does.

And I kind of have a bone to pick with Scientists who are actually contributing to the problem. Epigenetics is an essential biological process that takes place at the molecular level. Each one of the hundred trillion or so cells in the human body was created via the epigenetic process. Nothing has to magically happen. All you need is cells, food for the cells (usually glucose, yum!) and DNA.

Unfortunately, the amazing and fascinating research into epigenetics has led to a description of epigenetics as “genes plus environment.” If you are a scientist, or even understand science, you recognize that this does not mean that some sort of environmental factor from outside the body is necessary for the epigenetic process to take place. But if you’re a layperson, that’s exactly what you might think when you hear that. In fact, for quite some time I’ve been debating with a couple of people who believe in this magical concept of epigenetics, and you scientists (whom I otherwise love dearly) are just not helping!

The agouti mouse study that showed a change in coat color (linked along with other references in this previous post) was really exciting, and the public glommed onto it because there was the evidence, right in front of their eyes. In no time at all, alt-med proponents and the general public were certain that this was the answer to everything that was wrong with us. It was a great boon for supplement manufacturers, diet book writers, food conspiracy theorists, and anyone who was looking for something to blame for what was wrong with them (or society, but usually themselves.) I mean, clearly if what a mother mouse ate changed the color of her babies’ fur, then what horrible things are all these toxins doing to our genes?!?!

The thought seems to be that epigenetics is a highly unstable process that actually depends upon the correct “environment” in order to occur, and that even an unpleasant event in childhood can somehow upset it and result in a dramatic condition that can be passed down to one’s offspring. Once a person has gotten this idea into his head, it is darn nigh impossible to get it out. Homeopathic amounts of a “toxin” can have traumatic results, even worse than actual poisoning from that substance, because epigenetics. Psychiatric and neurological conditions are inflicted upon perfectly healthy infants by insufficient parental attachment or attunement. Everything is caused by environmental disruption of the epigenetic process, and everything in the environment messes up epigenetics.

Look, the reality is that what epigenetics does is take the information that’s been put into the RNA from the DNA, turn on the genes that are needed and turns off the ones that aren’t, then sends proteins off with the instructions to make new cells. At conception, when there are only a few cells, there’s not a lot of differentiation, but as fetal development continues, these instructions become more specific. “Make fingers.” “Make retinas.” “Make heart valves.” Stuff like that. During growth, the instructions are more like “make more of these cells.” During adolescence, it’s “make these a little different.” As we age, it’s “make another one just like this,” and “eh, what was that, sonny?”

The environment comes in because it is the epigenetic process during which an environmental factor can possibly alter the process, turning a genetic instruction on that should have been off or vice versa. It’s quite likely that this is what triggers many cancers that are strongly associated with exposure to a particular substance. But the possibility that exposure can impact gene expression is not the same as the inevitability of exposure altering gene expression. And this, people, is a big problem. Scientists, please think about this when you talk about epigenetics. Non-scientists, I’m going to put an explanation of how this works in the simplest terms I can come up with in another post.