Editor's pick: Depression and inflammation
It is interesting that the anti-inflammatory treatment infliximab has been found effective in cases of drug-resistant depression (27 June, p 38). Several studies have indicated that the conventional antidepressants known as selective serotonin reuptake inhibitors (SSRIs) owe at least part of their success to anti-inflammatory actions.
SSRIs to act on microglial cells in the brain to prevent production and release of TNF-alpha, the molecule that infliximab immobilises and renders ineffective.
Here we have two treatments that work, probably, by targeting the same molecule, TNF-alpha. I would expect them to produce similar clinical results; but the article refers to infliximab being successful in patients who did not respond to standard SSRI antidepressants.
So it seems that accepting the inflammatory basis for depression and other psychological conditions may only represent the beginning of our understanding. As so often, the immune mechanisms involved are far more complicated than we understand.
Glasgow, UK
Civilisation of the mind snatchers
Brian Horton’s letter suggests that infection with the parasite Toxoplasma gondii serves the interests of cats (13 June). The domestication of the cat coincided in human history with the rise of cities, which was helped along by cats’ ability to control rodents 鈥� enabling the stockpiling of grain. This created the opportunity for small groups to control food supplies and thus the rest of the people.
It is interesting to speculate on the effects of having a significant percentage of the human population engaging in risk-taking and fuelled with extra testosterone, as a result of Toxoplasma infection, during the period when the first cities were growing. Was this as important to the rise of cities as rodent control?
Heathcote, Victoria, Australia
Facebook’s going to be able to recognise your face… without even seeing it
“Contagious” is one of many to about Aviva Rutkin’s report (bit.ly/1LxRajf)
Toxoplasmosis and dopamine levels
I was struck by the ability of Toxoplasma to produce a precursor to dopamine, and by the correlation between infection with it and schizophrenia (30 May, p 42). In the same issue you report on fetal cell treatments for Parkinson’s disease, which is caused by an underactive dopamine system (p 11).
It would be interesting to compare the frequency of Toxoplasma infection in people with Parkinson’s and others living in the same area. My hypothesis is that the infection rate will be significantly lower in those with Parkinson’s.
On the other hand, it is possible that people with Parkinson’s will show a significantly higher rate of infection. That would suggest that the added dopamine causes their own dopamine system to fail.
Walnut Creek, California
Caribbean coral finds reef relief
Michael Slezak reports on the challenges coral faces in the Caribbean and elsewhere (20 June, p 36). It’s funny to see that years of sanctions can sometimes inspire people to move towards self-reliance. Along Cuba’s coast one of the largest and best-preserved coral reefs in the Caribbean has been thriving 鈥� although it now faces similar challenges to others.
Cuba’s fishing fleets are working hard to preserve the coast’s extraordinary marine diversity: the Gardens of the Queen are full of life, and the Gulf of Ana Maria is a unique ecosystem. After all, the livelihood of those who fish bonito depends on a healthy, resilient ecosystem just as much as a newborn turtle does.
Louth, Lincolnshire, UK
Drugs, evidence and fixed beliefs
David Nutt discusses “the unscientific and primitive… strategy” followed by a number of countries in legislating on recreational drugs (13 June, p 24). He fails to point out that these are motivated by an unshakeable belief among influential parts of their populations that it is morally wrong to get high.
For these people, regardless of evidence, those who like to get high are bad, and need to be discouraged from following their inclinations. While such believers may have been temporarily set back by the failure of prohibition, passing a law that makes any chemically induced high illegal seems right to them.
Toronto, Canada
Climate change and population
While most 快猫短视频 readers will welcome the pope’s encyclical on sustainability (27 June, p 24), the Catholic church is also implicated in the current parlous situation. Take as an example the Philippines, a country which is around 80 per cent Catholic. The population from 16 million in 1939 to roughly 60 million by 1990 and stands at around 105 million now.
The ban by the church on artificial contraception is a major contributing factor to our global problems.
Worcester, UK
Climate change and population
鈥� In a leader article we expressed the hope that the pope would embrace evidence-based change in areas beyond climate change, including contraception (17 January, p 5). But note that religiosity is not always coincident with increased birth rate: consider, for example, that is one of the lowest in the European Union.
Proliferating personality traits
In her article on personality traits, Clare Wilson reports Ivan Robertson saying that adopting a more accurate model based on six traits will make it harder to compare work to the existing five-trait model (13 June, p 11).
But the sixth 鈥� known as “Machiavellian” or honesty-humility 鈥� is just another trait. Why can results using this not be compared with studies of the “big five” traits (agreeableness, extroversion, neuroticism, conscientiousness and openness to new experiences)?
I think the principle sometimes called “Einstein’s Razor” applies: things should be made as simple as possible, but not simpler. So I am not sure there is a lot of value lost if a researcher cannot compare their results with what we now know is an inaccurate model.
San Antonio, Texas, US
Proliferating personality traits
鈥� It would be useful to compare newer studies using the six-trait model with older ones using five. But the five common factors are not identical across both models 鈥� there have been some changes to two of them.
Heavy fats are not as heavy as that
Part of Jessica Hamzelou’s fascinating article on heavy fats and longevity puzzled me (16 May, p 8). A molecule of linoleic acid contains 32 hydrogen atoms: if all were replaced with deuterium the mass per mole would increase by 32 grams to 312, not the 282 stated.
Lethbridge, Victoria, Australia
Heavy fats are not as heavy as that
鈥� In the heavy linoleic acid used by the team, two hydrogen atoms were replaced with deuterium.
Jazz improvisation ensemble DNA
Claire Ainsworth observes that “blueprint” is a lousy metaphor for what DNA does (13 June, p 42). The more that we have discovered about how genes function, the more the genome seems like an orchestra, performing a composition in successive movements. But the dynamism and interaction is something like an improvised jazz performance.
Maybe we can think of the development of an organism as a classical jazz symphony, performed by a very large group.
Sittingbourne, Kent, UK
Maxwell's Soviet science stash
I noted with interest the mention of Robert Maxwell’s Pergamon Press holding rights to the translations of the Soviet Academy of Sciences (Letters, 6 June). Not long after Maxwell’s death, I was asked to value a large collection of works held at a warehouse in Wolverton, Buckinghamshire. The collection included translations of Academy works, never released for sale. There were also words of wisdom from Kim Il-Sung of North Korea, the wit of Enver Hoxha of Albania, and any number of copies of Mao Tse-tung’s Little Red Book.
Bletchley, Buckinghamshire, UK
North Sea methane eruptions sought
Anil Ananthaswamy’s review of potential methane release from the seabed on the East Siberian Arctic Shelf reminded me of work at Newcastle University Ocean Engineering Research Group in the 1970s (23 May, p 38). My research associate, Alan Judd, found thousands of seabed pockmarks, ranging from less than a metre to tens of metres in diameter, on the floor of the northern North Sea in an area thought to have been glaciated during the last ice age 鈥� unlike the East Siberian Shelf.
As I recall, the pockmarks were attributed to post-ice-age methane eruptions but, as Ananthaswamy notes, there is no corresponding methane blip in Greenland ice core records.
Whitwell, Isle of Wight, UK
North Sea methane eruptions sought
鈥� Researchers indeed blamed shallow gas, and suggested that it may still have been erupting ().
<b>For the record</b>
鈥� At least we were consistent in being off by 1000: the solar system travels at 200,000 metres per second around the galactic centre; the Earth at 29,800 metres per second around the sun; and the International Space Station at 7700 metres per second around the Earth (27 June, p 28). We must speed up checking.
鈥� At Igor Pikovski’s request, we make it clear that he is probing the interplay of quantum mechanics and gravity, not quantum gravity (20 June, p 8).
鈥� We should have said that the calculated lifetime of neutrinos produced in the decay of superheavy dark matter is 1011 times the age of the universe (20 June, p 32).