Being overweight may protect people from cardiovascular mortality, researchers, including one of Indian-origin, have claimed.

High body mass index (BMI) is associated with multiple cardiovascular diseases. However, emerging data suggest that there is an "obesity paradox" - that being overweight may actually protect patients from cardiovascular mortality.

Investigators have confirmed that the risk of total mortality, cardiovascular mortality, and myocardial infarction is highest among underweight patients, while cardiovascular mortality is lowest among overweight patients, according to two reports published in the journal Mayo Clinic Proceedings.

Abhishek Sharma, Cardiology Fellow at the State University of New York Downstate Medical Center in Brooklyn, New York, and colleagues conducted a meta-analysis of 36 studies.

They determined that low BMI (less than 20 kg/m2) in tens of thousands of patients with coronary artery disease who underwent coronary revascularisation procedures was associated with a 1.8- to 2.7-fold higher risk of myocardial infarction and all-cause and cardiovascular mortality over a mean follow up period of 1.7 years.

Conversely overweight and obese patients had more favourable outcomes. Cardiovascular mortality risk was lowest among overweight patients with a high BMI (25-30 kg/m2) compared to people with a normal BMI (20-25 kg/m2).

In obese and severely obese patients with a BMI in the 30-35 and over 35 kg/m2 range, all-cause mortality was 27 per cent and 22 per cent lower than people with normal BMI.

"At this stage we can only speculate on the reasons for this paradox. One explanation may be that overweight patients are more likely to be prescribed cardioprotective medications such as beta blockers and statins and in higher doses than the normal weight population," Sharma said.

In the second study, investigators led by Carl Lavie, Medical Director of Cardiac Rehabilitation and Preventative Cardiology at the John Ochsner Heart & Vascular Institute, Ochsner Clinical School, at the University of Queensland School of Medicine in New Orleans examined the "obesity paradox" from another perspective.

They evaluated the effects of body composition as a function of lean mass index (LMI) and body fat (BF) on the correlation between increasing BMI and decreasing mortality.

They estimated BF and LMI in nearly 48,000 people with a preserved left ventricular ejection fraction of more than 50 per cent and examined the survival advantages of obesity across strata of these body compositions.

This large observational study showed that higher lean body mass was associated with 29 per cent lower mortality, and while higher fat mass also exhibited survival benefits, this advantage disappeared after adjustment for lean body mass, suggesting that non-fat tissue bears the primary role in conferring greater survival.

Expectant moms or women who are trying to get pregnant should avoid light during the night, according to a new research.

Darkness is important for optimum reproductive health in women, and for protecting the developing foetus, said study researcher Russel J Reiter, a professor of cellular biology at the University of Texas Health Science Center in San Antonio.

In a review of studies published in the journal Fertility and Sterility, Reiter and his colleagues evaluated previously published research, and summarised the role of melatonin levels and circadian rhythms on successful reproduction in females.

The evidence showed that every time the light at night was turned on, it turned down the production of melatonin, 'Live Science' reported.

Melatonin, a hormone secreted by the pineal gland in the brain in response to darkness, is important when women are trying to conceive, because it protects their eggs from oxidative stress, Reiter said.

"If women are trying to get pregnant, maintain at least eight hours of a dark period at night. The light-dark cycle should be regular from one day to the next; otherwise, a woman's biological clock is confused," he said.

Eight hours of darkness every night is also optimal during pregnancy, and ideally, there should be no interruption of night time darkness with light, especially during the last trimester of a pregnancy, Reiter said.

Turning on the light at night suppresses melatonin production in women, and means the foetal brain may not get the proper amount of melatonin to regulate the function of its biological clock, he said.

Hot and humid days may bring more kidney stones as higher temperatures contribute to dehydration that leads to a higher concentration of calcium in the body that promote the growth of kidney stones.

In a study involving 60,000 patients in the US, researchers found that as daily temperatures rose, there was a rapid increase in the number of patients seeking treatment for kidney stones.

"The findings point to potential public health effects associated with global climate change," said Gregory E. Tasian, a pediatric urologist and epidemiologist at the Children's Hospital of Philadelphia (CHOP).

It is likely that higher temperatures increase the risk of kidney stones in those people predisposed to stone formation.

The delay between high daily temperatures and kidney stone presentation was short, peaking within three days of exposure to hot days, the study added.

The team found that as frigid weather keeps people more in indoors, higher indoor temperatures, changes in diet and decreased physical activity may raise their risk of kidney stones.

The authors note that increase in greenhouse gas emissions are projected to raise earth's average temperatures by 1 to 4.5 degrees Celsius by 2100.

"Kidney stone prevalence has already been on the rise over the last 30 years, and we can expect this trend to continue as daily temperature increase," Tasian noted.

The paper was published in the journal Environmental Health Perspectives.

In what could help better treat and prevent gastrointestinal infection, researchers have used unique computational models to show how infection can affect bacteria that naturally live in our intestines.

"Our gut contains ten times more bacterial cells than there are human cells in our body," said Lynn Bry from Brigham and Women's Hospital in the US.

"The behaviour of these complex bacterial ecosystems when under attack by infection can have a big impact on our health," Bry added.

Researchers developed novel computer algorithms to analyse the different stages of infection when a pathogen known as Citrobacter rodentium, which causes disease in mice similar to food-poisoning in humans, was introduced into the guts of mice.

They generated a two-month time-series of the population levels of bacteria throughout multiple sites in the intestine.

The computational framework, known as Microbial Counts Trajectories Infinite Mixture Model Engine, was used to identify dynamic changes within the complex communities of bacteria in the gut associated with infection and inflammation.

The researchers observed many disruptions in the normal bacteria at different locations in the gut during the infection.

For instance, they discovered a microbial signature in the colon involving species belonging to the genus Mucispirillum that showed decreases early in infection before the onset of symptoms.

"From a clinical perspective, these new microbial signatures we identified could help clinicians detect early stages of inflammation or subtle persistent disease in patients with gastrointestinal disorders, such as inflammatory bowel disease," Bry added.

The study was published in the journal in PLOS ONE.

Aussie scientists have shunned the belief that low back pain are linked to weather conditions such as temperature, humidity, air pressure, wind direction and precipitation.

As per to the World Health Organization (WHO), nearly everyone experiences low back pain at some point in their life, making it the most prevalent musculoskeletal condition and affecting up to 33 percent of the world population at any given time. Those with musculoskeletal (bone, muscle, ligament, tendon, and nerve) pain report that their symptoms are influenced by the weather. Previous studies have shown that cold or humid weather, and changes in the weather increase symptoms in patients with chronic pain conditions.

Dr. Daniel Steffens form the University of Sydney said that patients believe that weather impacts their pain symptoms, but there were few robust studies investigating weather and pain, specifically research that does not rely on patient recall of the weather.

For the present case-crossover study, 993 patients seen at primary care clinics in Sydney were recruited between October 2011 and November 2012. Weather data from the Australian Bureau of Meteorology were sourced for the duration of the study period. Researchers compared the weather at the time patients first noticed back pain (case window) with weather conditions one week and one month before the onset of pain (control windows).

Results showed no association between back pain and temperature, humidity, air pressure, wind direction or precipitation. However, higher wind speed and wind gusts did slightly increase the chances of lower back pain, but the amount of increase was not clinically important.

Dr. Steffens concluded that their findings refute previously held beliefs that certain common weather conditions increase risk of lower back pain.

The study is published in the journal of the American College of Rheumatology, Arthritis Care and Research.