Researchers have put forward another theory to explain the cause behind acquiring Alzheimer`s disease: iron accumulation.

Dr. George Bartzokis, a professor of psychiatry at the Semel Institute for Neuroscience and Human Behavior at UCLA and senior author of the study and his colleagues looked at two areas of the brain in patients with Alzheimer`s.

They compared the hippocampus, which is known to be damaged early in the disease, and the thalamus, an area that is generally not affected until the late stages. Using sophisticated brain-imaging techniques, they found that iron is increased in the hippocampus and is associated with tissue damage in that area. But increased iron was not found in the thalamus.

While most Alzheimer`s researchers focus on the buildup of tau or beta-amyloid that results in the signature plaques associated with the disease, Bartzokis has long argued that the breakdown begins much further "upstream."

The destruction of myelin, the fatty tissue that coats nerve fibers in the brain, he says, disrupts communication between neurons and promotes the buildup of the plaques. These amyloid plaques in turn destroy more and more myelin, disrupting brain signaling and leading to cell death and the classic clinical signs of Alzheimer`s.

Myelin is produced by cells called oligodendrocytes. These cells, along with myelin, have the highest levels of iron of any cells in the brain, Bartzokis said, and circumstantial evidence has long supported the possibility that brain iron levels might be a risk factor for age-related diseases like Alzheimer`s.

Although iron is essential for cell function, too much of it can promote oxidative damage, to which the brain is especially vulnerable.

In the current study, Bartzokis and his colleagues tested their hypothesis that elevated tissue iron caused the tissue breakdown associated with Alzheimer`s disease. They targeted the vulnerable hippocampus, a key area of the brain involved in the formation of memories, and compared it to the thalamus, which is relatively spared by Alzheimer`s until the very late stages of disease.

The researchers used an MRI technique that can measure the amount of brain iron in ferritin, a protein that stores iron, in 31 patients with Alzheimer`s and 68 healthy control subjects.

In the presence of diseases like Alzheimer`s, as the structure of cells breaks down, the amount of water increases in the brain, which can mask the detection of iron, according to Bartzokis.

Bartzokis said that it is difficult to measure iron in tissue when the tissue is already damaged.

He said that the MRI technology that they used in this study allowed them to determine that the increase in iron is occurring together with the tissue damage.

Bartzokis asserted that they found that the amount of iron is increased in the hippocampus and is associated with tissue damage in patients with Alzheimer`s but not in the healthy older individuals - or in the thalamus. So the results suggest that iron accumulation may indeed contribute to the cause of Alzheimer`s disease.

The research has been published in the Journal of Alzheimer`s Disease.

Children who have higher levels of Bisphenol A, a chemical used in plastics, are more likely to become obese and have abnormal waist circumference, a new study has suggested.

The University of Michigan researchers studied the levels of BPA found in children`s urine and then measured body fat, waist circumference, and cardiovascular and diabetes risk factors, in a study published today in Pediatrics.

BPA was previously widely used in the manufacturing of polycarbonate and epoxy resins used in a variety of products for children, including baby bottles, protective coatings on metal food containers, plastic toys, and dental sealants.

Donna Eng, M.D., lead author of the study and recent graduate of the Pediatric Endocrinology Fellowship at C.S. Mott Children`s Hospital, said that studies in adults had shown an association between high BPA levels and obesity, diabetes and cardiovascular disease, but little was known about its effects in children.

The study found that higher odds of obesity, defined as a BMI above the 95th percentile on Centers for Disease Control and Prevention growth curves, was associated with higher levels of urinary BPA.

Researchers also found that children with higher BPA levels also were more likely to have an abnormal waist circumference-to-height ratio.

The study did not find significant associations of BPA with any other chronic disease factors, including abnormal levels of cholesterol, insulin or glucose levels.

Eng said that their study suggested a possible link between BPA exposure and childhood obesity. We therefore need more longitudinal studies to determine if there is a causal link between BPA and excess body fat.

Joyce Lee, M.D., M.P.H, associate professor of Pediatrics at C.S. Mott Children`s Hospital, said that they were surprised that their study did not find a link between BPA and measures of cardiovascular and diabetes risk, which has been established among adults.

She said that based on the results, BPA may not have adverse effects on cardiovascular and diabetes risk, but it`s certainly possible that the adverse effects of BPA could compound over time, with health effects that only later manifest in adulthood.

The study has been published in Pediatrics.

Scientists have been able to uncover the molecular mechanism by which the deadly Ebola virus assembles, providing potential new drug targets.

The study also showed that the same molecule that assembles and releases new viruses also rearranges itself into different shapes, with each shape controlling a different step of the virus`s life cycle.

Erica Ollmann Saphire, Ph.D., professor in the Department of Immunology and Microbial Science at TSRI, said that like a `Transformer`, this protein of the Ebola virus adopts different shapes for different functions.

He asserted that it revises a central dogma of molecular biology-that a protein molecule has one shape that predestines one biological function."

Zachary Bornholdt, Ph.D., senior staff scientist and first author of the study, said that drugs to block viral replication could target any of the structures themselves or the intermediate steps in the structural transformation process.

Ebola hemorrhagic fever is one of the most virulent diseases known to humankind. Very few pathogens prove more dangerous than Ebola virus once a person is infected. There is no cure, and the case-fatality rate can be up to 90 percent, depending on which strain is involved.

To conduct the study, Dr. Saphire and her group at TSRI collaborated with Yoshihiro Kawaoka , Ph.D., D.V.M., who holds joint appointments at the University of Wisconsin and University of Tokyo.

Dr. Kawaoka`s group provided cellular microscopy and critical replication experiments to complement the TSRI team`s expertise in x-ray crystallography and protein biochemistry.

The results, five years in the making, revealed the Ebola VP40 protein exists as a dimer, not as a monomer as previously thought, and it rearranges its structure to assemble filaments to build the virus shell or "matrix" to release countless new viruses from infected cells.

The study showed the protein also rearranges itself into rings in order to bind RNA and control the internal components of the virus copied inside infected cells.

This "shape-shifting" or "transformer" behavior explains how the Ebola virus can control a multi-step viral lifecycle using only a very limited number of genes.

The study has been published in the peer-reviewed journal Cell.

Children who drink soda tend to score slightly higher on scales that measure aggressive behaviour than kids who don`t drink the carbonated beverages, according to a new study.

The study`s lead author cautioned, however, that the increase may not be noticeable for individual children and the researchers can`t prove soda caused the bad behaviours.

"It`s a little hard to interpret it. It`s not quite clinically significant," Shakira Suglia, of Columbia University`s Mailman School of Public Health in New York, told Reuters Health.

Previous work by some of the study`s authors had found connections between soda drinking and violent behaviour, but the link had not been studied in young children.

For the new analysis, the researchers used an existing study of mothers and their 2,929 children from 20 large U.S. cities. The mothers and children were first recruited between 1998 and 2000 to be periodically interviewed and evaluated.

Mothers completed a checklist on children`s behaviours over the previous two months to measure withdrawal, attention and aggression.

"It`s things like how often does a child destroy his or her own belongings and how often do they destroy the belongings of others," Suglia said.

The mothers were also asked how many servings of soda their children drank per day and about other habits such as TV watching.

Overall, 43 percent of the kids drank at least one soda per day and 4 percent drank four or more servings.

Aggressive behaviour was measured on a scale between 0 and 100 - with higher scores indicating more aggression. Suglia said the average score is 50, and 65 is usually used as a clinical marker of when children should be evaluated for a problem.

Kids who reportedly drank no soda scored 56 on the aggression scale, on average. That compared to 57 among kids who drank one serving per day, 58 among those who drank two servings, 59 among those who drank three servings and 62 for four soda servings or more per day.

After taking into account habits that may have influenced the results - such as how much TV the kids watched, how much candy they ate and their mother`s race and education - the researchers still found that drinking two or four or more servings of soda per day was tied to higher aggression scores.

Overall, kids who drank four or more servings of soda per day were twice as likely to destroy other people`s belongings, get into fights and physically attack people, compared to children who didn`t drink soda.

Soda drinkers also scored higher on scales measuring signs of withdrawal and attention problems, write the researchers in The Journal of Pediatrics.

Suglia said that although the increased aggressive behaviour may not be noticeable for each child, it`s moving all kids closer to the scale`s clinical threshold.

"Furthermore, if they`re drinking this much soda, it`s probably taking away from other nutritional things the child could be eating," she said.

The researchers write that they can`t tell from their study what may explain the association between soda and behaviour problems in children, but one possibility is that an ingredient in soda - like caffeine or high fructose corn syrup - could directly increase aggression.

Another possibility, however, is that an underlying condition - such as low blood sugar - could make kids more aggressive and make them crave soda and sweets, they add.

Suglia also said it`s important to note that the results may not apply to the general population, because most of the mothers were single and African American or Latina.

Despite those limitations, Janet Fischel, director of developmental and behavioural pediatrics in the department of pediatrics at Stony Brook University School of Medicine in New York, said the study is a step in the right direction.

"I think it`s really important and a giant first step in gathering an evidence base for what`s becoming a very widespread dietary habit. I think that`s really important," Fischel, who wasn`t involved in the new study, said.

Two new studies have revealed that gut microbes known as fusobacteria, which are found in the mouth, stimulate bad immune responses and turn on cancer growth genes to generate colorectal tumours.

The findings could lead to more effective strategies for the early diagnosis, prevention, and treatment of colorectal cancer.

"Fusobacteria may provide not only a new way to group or describe colon cancers but also, more importantly, a new perspective on how to target pathways to halt tumour growth and spread," senior study author Wendy Garrett of the Harvard School of Public Health and the Dana-Farber Cancer Institute, said.

Colorectal cancer is the second leading cause of cancer-related death in the United States.

Recent studies have shown that fusobacteria from the mouth are also abundant in tissues from colorectal cancer patients. But until now, it was not known whether these microbes directly contribute to the formation of tumours.

In one of the new studies, Garrett, Matthew Meyerson of the Dana-Farber Cancer Institute, and their collaborators found that fusobacteria are prevalent in human adenomas-benign tumours that can become malignant over time-suggesting that these microbes contribute to early stages of tumour formation.

In a mouse model of colorectal cancer, these bacteria accelerated the formation of tumours by attracting immune cells called myeloid cells, which invade tumours and stimulate inflammatory responses that can cause cancer.

In the second study, Yiping Han of Case Western Reserve University School of Dental Medicine and her collaborators discovered that fusobacteria rely on a molecule called Fusobacterium adhesin A (FadA), which is found on the surface of these bacterial cells, to attach to and invade human colorectal cancer cells.

FadA then turns on cancer growth genes and stimulates inflammatory responses in these cells and promotes tumour formation.

Han and her team also found that FadA levels were much higher in tissues from patients with adenomas and colorectal cancer compared with healthy individuals.

Moreover, they identified a compound that can prevent FadA`s effects on cancer cells.