Melatonin – what will it do for you?

August 22, 2009

ResearchBlogging.orgIf you have chronic insomnia, but no octher psychiatric illnesses, will melatonin help you? This is the question addressed by a recent multi-center study by Geert Mayer and co-workers.

Chronic insomnia affects a large chunk of the population; papers cited by the authors have found a prevalence around 1 in 3 adults. It is a notoriously persistent condition and treatment is difficult. Many sleeping pills have unacceptable side effects (such as daytime drowsiness) and/or can only be used for short times. Behavioural interventions are difficult to sustain in the long run.

Hence the great interest in understanding how sleep is regulated, so that we can develop medications targeting the sleep cycle itself. Our circadian rhythms, i.e. the rhythms that tell us when it is morning, midday and night, are regulated by a brain area called the suprachiasmatic nucleus, where there is a collection of “clock cells”, that keep time in cycles of approximately 24 h. Another important component is melatonin secretion from the pineal gland, which synchronises the clock to the light/dark cycle of our environment. When it gets dark in the evening, melatonin secretion goes up.

Melatonin. Image from Wikipedia.

Melatonin. Image from Wikipedia.

So, why not give some extra melatonin 30 minutes before bedtime and see what happens to the sleep patterns? This is what Mayer et al did, with a placebo control group getting an identical-looking pill. Both groups kept doing it for 6 months, and the researchers recorded sleep patterns regularly as well as the subjective experiences of the patients, assessed by a questionnaire. Towards the end, they switched the treatment group over to placebo to see if there were any withdrawal symptoms. The drug they used was not melatonin itself but a synthetic compound called Ramelteon which binds to the same receptor.

What happened? Nothing, pretty much. The researchers monitored 20 different parameters, and found a statistically and clinically significant difference only in one: the latency to persistent sleep after going to bed. Patients on Ramelteon fell sleep faster. But they did not sleep better or longer. They did not have improved alertness or memory and they did not feel better in any way that the researchers asked for. On the other hand, there were just as many “adverse events” in the treatment and control groups, and no signs of withdrawal symptoms, so Ramelteon treatment seems not to be a risky business.

Now, it is necessary to exercise a bit of caution when interpreting a study that has many endpoints at the same time. The more endpoints you include, the higher is the likelihood that one of them will show a significant result purely out of chance. We should therefore be a little skeptical against the positive finding. Ramelteon seems to be in the league of making sacrifices to the god Hypnos – it doesn’t hurt, it could be a little expensive, and it’s not likely to help.

Hypnos (left) with his twin brother Thanatos (representing death). Painting by J W Waterhouse (1849-1917).

Hypnos (left) with his twin brother Thanatos (representing death). Painting by J W Waterhouse (1849-1917).

Melatonin could be great for some other uses that weren’t tested in this study – against jetlag, perhaps, or if you are having a manic episode and can’t sleep for that reason. The blogosphere’s number one chronobiologist Coturnix has an excellent overview post on sleep, including a bit on melatonin and its potential therapeutic uses.

Full reference:
Mayer G, Wang-Weigand S, Roth-Schechter B, Lehmann R, Staner C, & Partinen M (2009). Efficacy and safety of 6-month nightly ramelteon administration in adults with chronic primary insomnia. Sleep, 32 (3), 351-60 PMID: 19294955


Beauty in the abstract

July 27, 2009

Currently I am doing a spot of mathematical modelling, with the highly valuable assistance of my brother who is experienced with implementing models in MatLab.

Take a look at this graph, which emerged from his efforts today:

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More to come!


Selenite against mesothelioma – mechanism of action explained

July 17, 2009

ResearchBlogging.org

Our latest paper is now freely available online as a fully formatted pdf from the Journal of Experimental and Clinical Cancer Research. As I have promised, here is a non-technical summary!

What did we study?

This work is about malignant mesothelioma, an unusual type of cancer that is caused by asbestos. It is always deadly, and current treatment extends life expectancy only by a few months. We have been working for some time on a new experimental drug called selenite – a simple, selenium-based compound.

Interestingly, mesothelioma cells come in two kinds – epithelioid and sarcomatoid. If a tumor contains sarcomatoid cells, the patient will be expected to respond worse to therapy and die sooner. We have previously found that selenite is particularly effective against sarcomatoid cells, and that it is able to induce apoptosis, the “suicide program” of the cancer cells.

In this paper, we studied the apoptosis mechanisms in both epithelioid and sarcomatoid cells, to see if there were any differences that could explain why sarcomatoid cells are more sensitive. Also, very little was known about the apoptotic response to selenite in mesothelioma cells, we wanted to see how they compare to other cells.

What did we find?

Selenite caused the activation of a number of apoptosis signaling molecules. There was a difference between sarcomatoid and epithelioid cells in the activation of two proteins in the so-called Bcl-family. Sarcomatoid cells clearly overexpressed a protein called Bax. Perhaps this is part of the reason why they are more sensitive to selenite.

There is a “master regulator” of apoptosis called p53, and we investigated it rather thoroughly. It turned out that the cells amassed lots of p53 in their nuclei after selenite treatment, but it didn’t do anything! Normally, it would regulate the DNA and determine which genes should be read. But after selenite treatment, p53 became inactive and unable to regulate gene expression.

Cells stained for p53. Brown nuclei contain much p53 that is inactive. A and C are controls, B and D are treated with selenite. Sell the full paper for details (figure 2).

Cells stained for p53. Brown nuclei contain much p53 that is inactive. A and C are controls, B and D are treated with selenite. Sell the full paper for details (figure 2).

My greatest surprise was that the apoptosis signaling network was so robust and redundant. It’s really not a well-defined linear cascade of events, but rather an interlaced network of protein interactions which depend on and modulate each other. In this paper, we found that inhibition of some of the major apoptosis-signalling proteins had virtually no effect at all on the events following selenite treatment, even though we could prove that the inhibitors were effective in themselves.

What are the implications for the future?

We hope that selenite will become a useful drug for the treatment of mesothelioma in the future. If so, part of its mechanism of action has now been established.

Check out the full paper, it’s open access!

Nilsonne, G., Olm, E., Szulkin, A., Mundt, F., Stein, A., Kocic, B., Rundlöf, A., Fernandes, A., Björnstedt, M., & Dobra, K. (2009). Phenotype-dependent apoptosis signalling in mesothelioma cells after selenite exposure Journal of Experimental & Clinical Cancer Research, 28 (1) DOI: 10.1186/1756-9966-28-92


Do we need language to understand concepts?

July 14, 2009

AK doesn’t think so.

In another of his lengthy and well-researched posts, he argues that the understanding of more or less abstract concepts occurred in primates before a language based on words. This is based on a recent study of the mirror neurons in rhesus macaques. This research seems to indicate that rhesuses divide other rhesuses into two categories when the mirror neurons are activated: those within such a short distance that interaction is immediately possible, and those further away.

The post also includes an interesting reflection on how visual information is encoded in terms of a set of vectors in multidimensional space, suggesting that the same principle applies as a general form for representation in the brain.

In the process, AK also manages to discredit Plato’s idea that concepts are classes of things resembling an “ideal” concept that is by definition beyond our grasp. Instead, we construct concepts “bottom-up”, by grouping together objects and ideas that appear to us to have many similarities.

Implicit to AK’s argument is also the notion of a well-developed spatial modularity in the brain, with different areas encoding different concepts. While there is strong evidence for spatial modularity e.g. from split-brain experiments, showing that the two hemispheres can accurately identify and interact with objects independently of each other, it is very likely that at least some concepts are represented only by the concurrent activation of several areas in synchrony.


Monstrous effort to map a transcriptional network

July 8, 2009

ResearchBlogging.orgThe FANTOM consortium report in the latest issue of Nature Genetics that they have measured what happens with the entire, total, gene expression during the specific differentiation of a cell line called THP-1. Not the expression of just the 10 000 most important genes, all of them. At the same time.

Their findings are a heap of data which is probably larger than the whole body of research on medicine and biology up until the early 1900’s. If I try to say what their main finding is, I’d lean towards the interconnectedness of the signaling network. It doesn’t have one single weak spot, where you could knock out a certain gene and profoundly change the network dynamics. Knock-out of some genes had effects on many other parts of the network, but in general the system seems to be robust because of redundancy and interconnectedness. I have drawn similar conclusions in my own latest paper, though my methodology is a pair of binoculars compared to their multinational telescope.

Professor Hayashizaki of the RIKEN Omics Science Center was the general organiser of this study.

Professor Hayashizaki of the RIKEN Omics Science Center was the general organiser of this study.

My main thoughts, however, upon reading this paper were not so much about the actual research, but more about the way it was done.

  1.  With the advent of large-scale initiatives like these, we will perhaps have charted most of the “connectome” of the cell within the next decades. This is the map of the decision-making pathways. The neuroanatomy of the cell, if you wish. It has enormous potential to explain how, exactly, things go wrong in diseases such as cancer.
  2.  Biology is starting to resemble some branches of physics, where research advances through large concerted efforts. The author list of this paper is half a page long, with the authors’ affiliations taking up another half page. There will be less space for the nerdy loner scientists and greater demand for the entrepreneurial, outgoing kind of researcher in the future.
  3.  Seventeen figures and fourteen tables, and the whole methods section, have been relegated to the “supplementary material” that is only available online. Reporting on this kind of science in an 8-page article is like writing a short essay on “World War II”. I’m sure the best parts are in there, but you can’t begin to reenact it based on their descriptions. Lots of the interesting sub-analyses, which I presume must have been performed, will never see daylight. This is exactly the sort of science that benefits from the innovation of the online journal. No page limitations are needed there. Just last week, for example, I noticed that PlosOne had published a paper entitled “New Mid-Cretaceous (Latest Albian) Dinosaurs from Winton, Queensland, Australia”, which is 51 pages long and contains 40 illustrations, mainly of various bones photographed from different angles. Try getting that into a conventional journal!

Full reference:
Suzuki, H., Forrest, A., van Nimwegen, E., Daub, C., Balwierz, P., Irvine, K., Lassmann, T., Ravasi, T., Hasegawa, Y., de Hoon, M., Katayama, S., Schroder, K., Carninci, P., Tomaru, Y., Kanamori-Katayama, M., Kubosaki, A., Akalin, A., Ando, Y., Arner, E., Asada, M., Asahara, H., Bailey, T., Bajic, V., Bauer, D., Beckhouse, A., Bertin, N., Björkegren, J., Brombacher, F., Bulger, E., Chalk, A., Chiba, J., Cloonan, N., Dawe, A., Dostie, J., Engström, P., Essack, M., Faulkner, G., Fink, J., Fredman, D., Fujimori, K., Furuno, M., Gojobori, T., Gough, J., Grimmond, S., Gustafsson, M., Hashimoto, M., Hashimoto, T., Hatakeyama, M., Heinzel, S., Hide, W., Hofmann, O., Hörnquist, M., Huminiecki, L., Ikeo, K., Imamoto, N., Inoue, S., Inoue, Y., Ishihara, R., Iwayanagi, T., Jacobsen, A., Kaur, M., Kawaji, H., Kerr, M., Kimura, R., Kimura, S., Kimura, Y., Kitano, H., Koga, H., Kojima, T., Kondo, S., Konno, T., Krogh, A., Kruger, A., Kumar, A., Lenhard, B., Lennartsson, A., Lindow, M., Lizio, M., MacPherson, C., Maeda, N., Maher, C., Maqungo, M., Mar, J., Matigian, N., Matsuda, H., Mattick, J., Meier, S., Miyamoto, S., Miyamoto-Sato, E., Nakabayashi, K., Nakachi, Y., Nakano, M., Nygaard, S., Okayama, T., Okazaki, Y., Okuda-Yabukami, H., Orlando, V., Otomo, J., Pachkov, M., Petrovsky, N., Plessy, C., Quackenbush, J., Radovanovic, A., Rehli, M., Saito, R., Sandelin, A., Schmeier, S., Schönbach, C., Schwartz, A., Semple, C., Sera, M., Severin, J., Shirahige, K., Simons, C., St. Laurent, G., Suzuki, M., Suzuki, T., Sweet, M., Taft, R., Takeda, S., Takenaka, Y., Tan, K., Taylor, M., Teasdale, R., Tegnér, J., Teichmann, S., Valen, E., Wahlestedt, C., Waki, K., Waterhouse, A., Wells, C., Winther, O., Wu, L., Yamaguchi, K., Yanagawa, H., Yasuda, J., Zavolan, M., Hume, D., Arakawa, T., Fukuda, S., Imamura, K., Kai, C., Kaiho, A., Kawashima, T., Kawazu, C., Kitazume, Y., Kojima, M., Miura, H., Murakami, K., Murata, M., Ninomiya, N., Nishiyori, H., Noma, S., Ogawa, C., Sano, T., Simon, C., Tagami, M., Takahashi, Y., Kawai, J., & Hayashizaki, Y. (2009). The transcriptional network that controls growth arrest and differentiation in a human myeloid leukemia cell line Nature Genetics, 41 (5), 553-562 DOI: 10.1038/ng.375


The Scientia Pro Publica blog carnival is up

June 15, 2009

Scientia Pro Publica

The sixth edition of the Scientia Pro Publica blog carnival is hosted by Kelsey Abbott at the Mauka to Makai blog. Among the rousing stories of sex, drugs, cannibalism, phylogenetic classification, and sheer madness, you will also find my recent post on Open Access publishing.

Head over there and have a look!


Who is the woman in your relationship?

June 14, 2009

For some, it’s a bitter fight. Check out this video of two flatworms mating!

The first one who gets stabbed by the other’s penis will become the mother, and both are struggling with gusto and determination for the fatherhood.

Hat tip: Deep Sea News.


I appear in French!

May 12, 2009

The WordPress software gives me interesting statistics. For example, it tells me which Google search terms have landed people here. Today the top-ranking search was “hund cm kg diagramm”, followed by “robert browne the physist” and “cells growing on top of each other”. Kind of poetic.

But not as lyrical as the French translation of my blog (again, thanks to Google), that is apparently out there on the web.

Try this:

Certains organismes pluricellulaires émettent de la lumière dans un chemin. Fireflies procéder balises qui brillent dans la nuit, et certains poissons de haute mer phosphorescente utilisation appendices pour attirer ses proies. Cependant, les renseignements contenus dans la lumière de ces émissions est sans doute pas plus de «Je suis ici”, ou peut-être “Je suis aller dans une direction avec une certaine vitesse”.

It’s the first paragraph of an older post of mine. Some metazoans shed light on the road, do you suppose? The original read like this:

Some multicellular organisms emit light in a conspicuous way. Fireflies carry beacons that shine in the night, and some deep-sea fishes use phosphorescent appendages to attract prey. However, the information content in these light emissions is probably no greater than “I am here”, or possibly “I am moving in a certain direction with a certain velocity”.

Absurdity. I love it! And on a more serious note, I wonder how long it takes before I will actually be able to communicate straight to the majority of the world’s population, through automated translation?

UPDATE: And it gets even better when the circle completes one more rotation:

Quelques métazoaires de faire la lumière sur la route, faites-vous supposer?


Fun with a fluorescence microscope

May 12, 2009

I have a new friend. It is a Leica DM RXA fluorescence microscope. She is not a baby anymore, but her senses are sharper than a razor, quite literally!

We spent some time together this afternoon. Here are some of the results:

Glomerulus

Tubuli

You will get a chance to guess what it is before I give it away!


The heart regenerates. I stand corrected, with pleasure!

April 28, 2009

So, today I have lectured for five hours on the diseases of the cardiovascular system. It’s the fifth consecutive year that I have the honour of lecturing on this topic for some of the undergraduates in our department.

Dissection of the thorax and abdomen, shown in situ. Joseph Maclise, 1856.

Dissection of the thorax and abdomen, shown in situ. Joseph Maclise, 1856.

One aspect that I have always brought up is that heart muscle cells essentially don’t reproduce in adulthood. This is why a myocardial infarction leaves a permanent fibrous scar, that will remain for life. The heart cannot heal back to its normal functionality. And the low proliferative capacity of the heart muscle cells is probably closely linked to the strange phenomenon that they never give rise to cancer.

Alas, this has changed. A paper appeared just a few days ago from the Frisén laboratory showing that heart muscle cells do proliferate, but slowly. About half of them are replaced at some point during adulthood. The technique used to demonstrate this is based on the detection of carbon-14, levels of which increased dramatically in the entire atmosphere of the earth in the 1950’s and 60’s due to test detonations of nuclear bombs. The DNA in heart muscle cells from people who were already adults at that time was found to contain far more carbon-14 than expected, indicating that new cells had been formed.

Science has a podcast with Jonas Frisén where he explains what it’s all about.

When I was in high school, I used to wonder what it felt like to be a teacher, when old knowledge was proven false. Suddenly, I thought, a lot of past work would seem counterproductive.

But this is not how I feel at all! It’s a delightful sensation, a feeling of moving forward.

This reevaluation is a reminder that all our knowledge is provisory, and can be overturned at any time by new evidence. I shudder to think of a world where we didn’t question our old beliefs.


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