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Peripheral nerves in E11.5 mouse embryo (5x)
Johns Hopkins School of Medicine, Baltimore, Maryland, USA
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The art of medicine consists of amusing the patient while nature cures the disease.
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Thirteen years ago, an article in this journal first reported that the anesthetic medication, ketamine, showed evidence of producing rapid antidepressant effects in depressed patients who had not responded to prior treatments. Ketamine works by blocking one of the targets for the neurotransmitter glutamate in the brain, the N-methyl-D-aspartate (NMDA) glutamate receptor.
Now, a new study in Biological Psychiatry reports that enhancing, instead of blocking, that same target — the NMDA glutamate receptor — also causes antidepressant-like effects.
Sarcosine is one such compound that acts by enhancing NMDA function. Collaborators from China Medical University Hospital in Taiwan and the University of California in Los Angeles studied sarcosine in an animal model of depression and, separately, in a clinical trial of depressed patients.
"We found that enhancing NMDA function can improve depression-like behaviors in rodent models and in human depression," said Dr. Hsien-Yuan Lane, the corresponding author on the article.
Chih-Chia Huang, I-Hua Wei, Chieh-Liang Huang, Kuang-Ti Chen, Mang-Hung Tsai, Priscilla Tsai, Rene Tun, Kuo-Hao Huang, Yue-Cune Chang, Hsien-Yuan Lane, Guochuan Emil Tsai. Inhibition of Glycine Transporter-I as a Novel Mechanism for the Treatment of Depression. Biological Psychiatry, 2013; 74 (10): 734 DOI: 10.1016/j.biopsych.2013.02.020
Hospital-acquired infections are a serious health problem. One potential source of contamination is through the spread of pathogen-bearing droplets emanating from toilet flushes. The video above includes high-speed flow visualization of the large and small droplets that get atomized during the flush of a standard hospital toilet. Both are problematic for the spread of pathogens; the large droplets settle quickly and contaminate nearby surfaces, but the small droplets can remain suspended in the air for an hour or more. Even more distressing is the finding that conventional cleaning products lower surface tension within the toilet, aggravating the problem by allowing even more small droplets to escape. (Video credit: G. Traverso et al.)
Human brain specimen with glioblastoma multiforme.
Brain Cancer Cells Hide While Drugs Seek
Tumor cells temporarily lose mutation to evade drugs targeting mutation
A team of scientists, led by principal investigator Paul S. Mischel, MD, a member of the Ludwig Institute for Cancer Research and professor in the Department of Pathology at the University of California, San Diego School of Medicine, has found that brain cancer cells resist therapy by dialing down the gene mutation targeted by drugs, then re-amplify that growth-promoting mutation after therapy has stopped.
The findings are published in the December 5, 2013 online issue of Science.
“This discovery has considerable clinical implications because if cancer cells can evade therapy by a ‘hide-and-seek’ mechanism, then the current focus (of drug therapies) is unlikely to translate into better outcomes for patients,” said Mischel.
In recent years, new cancer therapies have emerged that target tell-tale gene mutations to identify specific cancer cells for destruction. Unfortunately, a variety of “resistance mechanisms” have also emerged, among them incomplete target suppression, second-site mutations and activation of alternative kinases or enzymes that maintain growth-promoting signals to the cancer itself.
“Most research is aimed at developing better drugs or better drug combinations to suppress these downstream signals,” Mischel said. “However, one thing that has not been carefully considered is whether cancer cells can modulate the levels of – and thus their dependence on – the target of the drug, evade therapy, and then re-acquire the oncogene to promote tumor growth when the drug is withdrawn.”
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Poaching by its very nature happens out of sight and out of hearing of most people. But in the forests of Africa, someone is listening.
Last week, audio from the Elephant Listening Project was released, featuring the actual moment an elephant was killed by poachers (see video). The low-frequency recording, which sounds almost abstract, was captured by some of the special microphones set up by the project in the forests of Gabon and the Republic of Congo. The aim is to monitor the sounds that forest elephants use to communicate, which humans can sometimes feel but barely hear.
Nature interviewed behavioural ecologist Peter Wrege of the The Cornell Lab of Ornithology at Cornell University in Ithaca, New York, who directs the project, which is largely funded by the US Fish and Wildlife Service programme ‘Wildlife Without Borders’.
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Paramecium sp. showing the nucleus, mouth and water
expulsion vacuoles (40x)
Rogelio Moreno Gill
Panama City, Panama
Technique: Differential Interference Contrast
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Tiny bits of plastic trash could spell big trouble for marine life, starting with the worms, say a team of researchers from Plymouth University and the University of Exeter who report their evidence in a pair of studies in the Cell Press journal Current Biology on December 2. Those marine worms play a key ecological role as an important source of food for other animals.
Work by Stephanie Wright from the University of Exeter found that if ocean sediments are heavily contaminated with microplastics, marine lugworms eat less and their energy levels suffer. A separate report, from Mark Anthony Browne on work performed at Plymouth University, shows that ingesting microplastic can also reduce the health of lugworms by delivering harmful chemicals, including hydrocarbons, antimicrobials, and flame retardants, to them.
"These chemicals are persistent, meaning they could accumulate in the tissue of organisms and take a long time to break down," says Richard Thompson of Plymouth University. "Our laboratory studies provide the first clear evidence that microplastics could cause harm and show that this could result from both the physical presence of ingested plastic and chemical transfer. Our next steps will be to establish the full implications of these findings for organisms in natural habitats."
Current Biology, Wright et al.: “Microplastic ingestion decreases energy reserves in marine worms”
Caption: Microscopic fragments of plastic — or microplastics — are pieces of plastic less than 5 mm in diameter and are a global marine pollutant. This image shows microplastic fragments and pre-production pellets collected from a sandy shoreline in Europe; these items are continually fragmenting in the environment. Experiments were conducted with sediment dwelling marine worms, showing that chemically inert microplastics of a size similar to sand grains from the beaches in which the worms lived caused physical harm (Wright et al.) whilst Browne et al. showed microplastic can move pollutants and additives to worms, reducing functions linked to health and biodiversity. Credit: Current Biology, Wright et al.
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The process of mitophagy, in which tiny digestive bubbles surround the mitochondria, serves to recycle waste for the cell. Damaged proteins can no longer carry out their function correctly and need to be broken down. Errors in the digestion of mitochondria appear in old age and in the case of neurodegenerative diseases like Parkinson’s and Alzheimer’s.
Up to now, it was unclear whether this cells sorted out defective proteins when they digest mitochondria. Dr. Jörn Dengjel from the Center for Biological Systems Analysis (ZBSA), Freiburg Institute for Advanced Studies (FRIAS), and the Cluster of Excellence BIOSS Centre for Biological Signalling Studies of the University of Freiburg has now discovered in collaboration with researchers from the Hebrew University in Jerusalem, Israel, that the proteins are sorted out during the constant fusion and fission of mitochondria. The team published their findings in the journal Nature Communications.
Hagai Abeliovich, Mostafa Zarei, Kristoffer T. G. Rigbolt, Richard J. Youle, Joern Dengjel. Involvement of mitochondrial dynamics in the segregation of mitochondrial matrix proteins during stationary phase mitophagy. Nature Communications, 2013; 4 DOI: 10.1038/ncomms3789
Yeast cells digest their mitochondria in long-time cultures. This process is called mitophagy. Proteins that are digested at a different speed are marked with a fluorescent dye. (Credit: © Joern Dengjel)
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