A new paper says that altered gut microbiota in humans is associated with symptomatic atherosclerosis and stroke. 

The human body contains ten times more bacterial cells than human cells, most of which are found in the gut. These bacteria contain an enormous number of genes in addition to our host genome, and are collectively known as the gut metagenome. How does the metagenome affect health? It's unclear, other than that probiotic foods are a $30 billion placebo. But specifics are currently being addressed by researchers in metagenomic research. 

In America, human women wake up every day and decide whether they want to have sex or not.  They know somewhere a man is willing to make that happen.

In bushcrickets, the male is in charge. 

When bushcrickets mate, the male attaches a spermatophore to the female's abdomen. Alongside the sperm themselves, the spermatophore contains a protein-rich mass that the female eats after mating. It then takes several hours for the sperm to find their way into the female's reproductive tract. 

Who decides when this 'bridal present' is delivered? A paper by Bielefeld biologists Professor  Klaus Reinhold and Dr. Steven Ramm says the male determines the dynamics of this process, even long after he has 'hopped off' somewhere else. 

Higher rates of schizophrenia are found in urban areas and it can be attributed to increased deprivation, increased population density and an increase in inequality within a neighborhood, says a new paper.

Dogs can sniff out Clostridium difficile, the infective agent that is responsible for many of the dreaded "hospital acquired infections", in stool samples and even in the air surrounding patients in hospital with a very high degree of accuracy, finds a study in the Christmas issue published on bmj.com today.

Yes, dogs can smell a superbug infection in poop. Can you smell a rat at BMJ this Christmas?

The findings, they write in one of this year's spoofs, support previous studies of dogs detecting various types of cancer and could have great potential for screening hospital wards to help prevent C. difficile outbreaks, say the researchers.

Opinions of the tooth fairy as kind and giving may need to be revised following "mounting reports of less child-friendly activity", according to a paper published in the BMJ's Christmas edition which is sure to fool mainstream media editors who are used to scare journalism and miracle vegetable of the week stories and may want to mix it up a little. 

Researchers from across London, they write, have become concerned following misdemeanors of the mythical character and a worrying trend in malpractice. One boy in particular became extremely distressed because the tooth fairy "had put a tooth in his left ear" after he left it under his pillow.

 An investigation turned out he was right. 

Our immune system does not shut down with age, says a new study published in PLOS Pathogens today. T cells can respond to virus infections in an older person with the same vigor as T cells from a young person.

Researchers examined individuals, younger than 40, between 41 to 59 years of age and older than 60, infected with three different viruses, including West Nile, and found the older group demonstrated perfectly normal immune responses.

Both the number of virus-fighting T cells and the functionality of the T cells were equivalent in all three groups.