The ‘wiring’ of the human brain, it appears, may be somewhat similar to more mechanic complex networks such as social networks and the World Wide Web.
At least, that’s one of the conclusions drawn by a group of British and American scientists who say that by modelling the trade-off between two competing ways of making useful connections, they created a complete statistical picture of the human brain’s complex network.
This simple mathematical model not only helps us better understand healthy brains, but also offers unique insights into schizophrenia and similar disorders, they say.
Writing in a recent issue of the Proceedings of the National Academy of Sciences (PNAS), they say that until this study, we knew little about the rules involved in the shaping of the human brain network, as the authors explain in their background information:
The lead author of the study is Ed Bullmore, a professor in the Department of Psychiatry, Behavioural and Clinical Neuroscience Institute, at the University of Cambridge in the U.K.
"Although a sophisticated set of measures is available to describe the topology of brain networks, the selection pressures that drive their formation remain largely unknown," the authors wrote.
Bullmore and colleagues found they could produce a good model from two competing pressures: a ‘distance penalty’ for maintaining long-range connections, and a preference to link regions (including those quite far apart), that share similar input. At first they just had the first one, but then when they introduced the second one, the model greatly improved, as Bullmore himself explains:
“There is a huge amount of evidence that the wiring of brain networks tends to minimize connection costs. Less costly, short-distance connections are much more numerous than more costly, long-distance connections. So our model realistically includes a distance penalty on long-distance connections, which will tend to keep connection costs low.”
They calibrated the model using functional magnetic resonance imaging (fMRI) data from one set of healthy volunteers, and then showed it provided a good fit to networks estimated in a second independent data set.
Furthermore, by slightly ‘detuning’ the model so it favoured more connections between distant brain regions, they found it “generated a reasonable simulation of the abnormal properties of brain functional networks in people with schizophrenia.”
Co-author Dr Petra E. VĂ©rtes, also of the University of Cambridge, says, “This result echoes some prior neuroimaging results which suggest that brain networks in schizophrenia may be associated with an abnormal trade-off between connection costs and other topological properties of brain networks.”
Mothers who were born in India, but now live in Canada, are considerably more likely to give birth to boys as their second or third births than Canadian women.
That’s the conclusion offers in a new study published in the Canadian Medical Association Journal.
Dr. Joel Ray of the St. Michael's Hospital and University of Toronto said the findings raised questions about why there are more male than female children among Indian couples who have had two or more previous babies.
In a male:female ratio study, researchers from St. Michael's Hospital and the University of Toronto examined 766,688 single live births in Ontario between 2002 and 2007. The births were categorized by the mother’s country or region of birth and the investigators also considered the father’s country of birth and calculated the male:female ratio of live births by country or region and on how many previous deliveries the mother already had.
The findings showed that the male:female ratio for most women was 1.05. That remained unchanged, regardless of the number of previous births. But for Indian and South Korean women with previous children, the likelihood of giving birth to a male child was substantially higher, and even higher than that for Indian-born women with more than one previous child.
“Whether this difference in sex ratios was the result of prenatal sex selection should be determined by direct study of practices of sex-selected preimplantation and pregnancy termination among individuals from various world regions,” suggest the authors. “In addition, an analysis of the duration of residence in Canada, access to fertility care, family income and parental preferences would be of value in describing factors that might influence prenatal sex selection.”
Helpful protein family found
A family of proteins that could potentially be used as biomarkers to predict resistance to chemotherapy in estrogen receptor-positive (ER-positive) breast cancer patients has been identified by researchers at the University of Hull in Britain.
In an ‘in press’ issue of their study published online in the Journal of Proteomics on April 3, lead researcher Dr. Lynn Cawkwell and colleagues explain how they discovered a number of potential biomarkers for resistance to epirubicin, docetaxel and other chemo drugs.
Resistance to chemotherapy is a big problem in the treatment of some types of cancer. Some patients with resistant cancers suffer the side effects of ineffective chemo options without the benefits, plus they lose valuable time until an effective therapy is found.
Thus, a major goal in cancer research is to predict how particular cancers might respond, and one way to do this is to test for particular proteins or biomarkers.
In a study published online in the Journal of Proteomics, lead researcher Dr. Lynn Cawkwell said a reliable test hasn’t yet been developed but she’s hopeful their work will “bring us a step closer.”
Some scientists working in this field use cell lines to try to track down biomarkers, but Cawkwell's team used clinical breast tumour tissue samples taken from patients, which she says helped them gain a “more accurate representation of what is relevant in real-life diseases.”
The team also used two ‘high-throughput processes,’ one based on antibodies and the other using mass spectrometry, to identify candidate biomarker proteins.
Using these to conduct ‘comparative proteomic experiments,’ they identified 132 unique proteins that were significantly differently expressed (more than two-fold) in chemo-resistant samples, 57 of which were identified in at least two experiments.
Cawkwell said the team is now working on showing how these proteins might be used as biomarkers to predict chemo-resistant ER-positive breast cancers.
“If we're correct, we hope that by testing for these proteins, doctors will be able to anticipate a patient’s response to different chemotherapies, and decide which course of treatment is most appropriate for them.”
Taking a baby for a needle is always a stressful time for parents and an occasion when the child almost always cries and tries to get away from the person giving the needle.
Now researchers in the U.S. are saying the 5Ss – swaddling, sucking, swinging, shushing, and side/stomach position – can reduce the child’s distress and crying.
Writing in the journal Pediatrics, researchers from Eastern Virginia Medical School say parents might be able to help their babies after a vaccination by simply holding and comforting their baby.
In this prospective, randomized, placebo-controlled trial involving 230 infants aged two and four months, the babies were randomly selected into one of four groups in which a combination of two variables were used – water versus sugar, and standard-of-care comfort measures (e.g. pacifiers and distraction) versus the 5Ss.
Using the Modified Riley Pain Score to determine the babies’ pain levels at 15-second intervals after their injection for two minutes, the authors found that those in the 5Ss groups had considerably lower pain scores, in both the sugar and non-sugar groups. In other words, the 5Ss are what had the pain-lowering impact, rather than the sugar.
Still, they add, breastfeeding an infant immediately after vaccination may be the best way to comfort the child and reduce their distress from pain.
Adult women who suffer from urinary incontinence can benefit by performing pelvic floor muscle training exercises that have no adverse effects, says a report from the U.S. Department of Health and the Agency for Healthcare Research and Quality (AHRQ).
The report also found that although medication treatments can be effective, their benefits are low and adverse effects are common.
AHRQ director Carolyn Clancy said urinary incontinence can affect women in a variety of ways, including physically, psychologically and socially – and some of these impacts can be severe.
“This new report,” she said, “will help women and their clinicians work together to find the best treatment option based on each patient’s individual circumstances.”
It’s estimated that about 25 per cent of young women, up to 57 per cent of middle-aged and postmenopausal women, and about 75 per cent of older women in nursing homes suffer from urinary incontinence. Urinary incontinence can inflict considerable and potentially debilitating lifestyle restrictions.
The team focused on stress incontinence and urgency incontinence. Stress incontinence is the inability to retain urine during sneezing or coughing and urgency incontinence is a sudden compelling urge to urinate that results in involuntary loss of urine.
The researchers found that both stress and urgency incontinence usually occur when the urinary sphincter fails, often due to weak pelvic floor muscles. Pelvic floor muscles support the bladder, uterus and other pelvic organs.
Those exercises designed to increase the strength of the pelvic floor muscles (similar to Kegel exercises) were effective in a women's ability to hold their urine. In addition to bladder training, the exercises also improved both stress and urgency incontinence.
Although the report found that estrogen treatment was effective in treating stress incontinence, it also had some adverse effects. Furthermore, another medication called duloxetine (antidepressant) was found to be ineffective and had a high risk of adverse effects.
According to the report, the drugs reviewed were comparable in effectiveness, although more women discontinued treatment with some drugs as a result of adverse effects.
