Fatty fish reduces breast cancer risk
A LARGE systematic review and meta-analysis involving more than 880 000 participants has provided “solid and robust evidence” that consumption of the fatty acids in fish is associated with a lower risk of breast cancer. The research, published in the BMJ, examined prospective cohort breast cancer studies, which included 20 905 cases of breast cancer, according to fish intake, n-3 polyunsaturated fatty acid (PUFA) intake, or tissue biomarkers. The researchers found a 14% reduction in breast cancer cases in the highest category of marine n-3 PUFA intake compared with the lowest category of intake. The risk was lowest in Asian populations, probably because of higher fish intake in Asia compared with western countries, the authors wrote. “Systematic review and meta-analysis are the most powerful tools to assess these kinds of inconsistent associations”, the authors wrote. “Therefore, our present study provides solid and robust evidence that marine n-3 PUFA are inversely associated with risk of breast cancer. The protective effect of fish or individual n-3 PUFA warrants further investigation of prospective studies.”

Brain injury linked to stroke
TRAUMATIC brain injury (TBI) has a “robust association” with ischaemic stroke, independent of other risk factors, according to a large observational study published in Neurology. The researchers found that TBI was “responsible for more ischemic stroke than hypertension” in the population studied, which involved 1 173 353 hospitalised trauma patients in California between 2005 and 2009, including 436 630 (37%) with TBI. The median follow-up in the study was 28 months, with a total of 11 229 (1%) strokes identified — 1.1% in the TBI group and 0.9% in the non-TBI trauma group. Patients with TBI were slightly younger than the non-TBI patients (mean age 49.2 v 50.3 years), less likely to be female (46.8% v 49.3%), and had a higher mean injury severity score (4.6 v 4.1). After adjustment, TBI was independently associated with subsequent ischemic stroke (hazard ratio [HR] 1.31, 95% confidence interval 1.25–1.36). “The magnitude of this association was substantial (HR 1.31) and was similar to the association between the leading stroke risk factor, hypertension (HR 1.34), and ischemic stroke”, the researchers wrote. The researchers said “further work is needed to assess whether [TBI] may be a novel stroke risk factor”.

Genetics predicts asthma persistence
NEW research suggests that genetic risks can predict which individuals with childhood-onset asthma will have reduced disease over time and which will develop life-course-persistent asthma. The research, published in The Lancet Respiratory Medicine, involved an analysis of data from 880 cohort members of the population-based Dunedin Multidisciplinary Health and Development Study (n = 1037), which has been running for 40 years. The researchers found that those at higher genetic risk developed asthma earlier in life than did those with lower genetic risk. The researchers used a genetic risk score approach to study the aggregate effect of several asthma-associated single nucleotide polymorphisms. “Such whole-genome scores are a work in progress in the case of asthma”, they wrote. Using this risk score they found that in participants with childhood-onset asthma, a higher genetic risk was more likely to lead to life-course-persistent asthma than those with a lower genetic risk. Children with asthma and higher risk scores comprising multiple genetic variants linked to asthma were 36% more likely to develop life-long-persistent asthma than those with a lower genetic risk. The researchers said the predictions were not sufficiently sensitive or specific to support immediate translation into clinical practice.

H7N9 flu infection not as bad as expected
HUMAN infections with avian influenza A H7N9 virus may be less serious than previously suspected, according to research published in The Lancet. Chinese researchers used information from the Chinese Center for Disease Control and Prevention to identify 123 patients with laboratory-confirmed avian influenza A H7N9 virus infection admitted to hospital. Of these, 37 (30%) had died and 69 (56%) had recovered by the end of May. The researchers said that, as with seasonal influenza, the severity of avian influenza A H7N9 virus infection increased with age; 71 (58%) of the 123 people admitted to hospital were aged at least 60 years. They estimated the fatality risk for all ages to be 36%. “Although most patients with laboratory-confirmed infection needed to be admitted to hospital and most of these required admission to intensive care units, the fatality risk for patients with avian influenza A H7N9 infection who were admitted to hospital of 36% seems to be lower than that for influenza A H5N1 in China (65%) and worldwide (60%), but higher than that for the 2009 influenza A H1N1 pandemic virus (21%)”, the researchers wrote. They said many mild cases might already have occurred, but continued vigilance and sustained intensive control efforts were needed to minimise the risk of human infection.

Vaccines don’t increase Guillain-Barré risk
A LARGE retrospective study published in Clinical Infectious Diseases has found no evidence of an increased risk of Guillain-Barré syndrome (GBS) following vaccinations of any kind, including influenza. Researchers identified 415 incident GBS cases among hospitalised patients registered with Kaiser Permanente Northern California between 1995 and 2006. Among the 415 cases, only 25 had received any vaccine in the 6 weeks prior to GBS onset. Of more than 6.8 million trivalent inactivated vaccine (TIV) doses administered, the researchers identified 18 cases of GBS within 6 weeks of TIV. With non-TIV vaccinations, there were seven cases within 6 weeks of a vaccine, only one of which had no prior illness. The relative risk of influenza vaccination within a 6-week interval prior to GBS, compared with the prior 9 months, was 1.1 (95% CI, 0.4–3.1). The risk in the 6-week interval compared to the prior 12 months for tetanus–diphtheria combination was 1.4 (95% CI, 0.3–4.5), 23-valent pneumococcal polysaccharide was 0.7 (95% CI, 0.1–2.9), and for all vaccines combined it was 1.3 (95% CI, 0.8–2.3). “In this study spanning 13 years and over 30 million person-years, using a case-centered method to control for seasonality and other time-varying confounders, we found no evidence of an increased risk of GBS following any vaccination, as well as all vaccinations combined”, the researchers wrote.

Ultra ultramarathon causes less damage
RESEARCHERS have discovered that, paradoxically, the world’s longest and most challenging mountainous ultramarathon (MUM) caused less neuromuscular fatigue, muscle damage and inflammation in runners than shorter MUMs. The research, published in PLOS One, involved 15 runners who competed in the 330 km trail run, which had 2400 m of positive and negative elevation change, in a median time of 122.43 hours. The aim of the study was to assess the physiological impact of the world’s most challenging MUM — the 2011 Tor des Géants (TdG) around the province of Val d’Aoste in Italy. “This competition is unique since it represents the greatest elevation change and distance ever performed over a single-stage mountainous ultra-marathon, inducing an amazing level of sleep deprivation”, the researchers wrote. They said the reduction in speed, the sleep deprivation and the underlying pacing regulation were among the factors explaining a reduced strength loss observed in those competing in the TdG, when compared with runners in a shorter distance MUM. “During the second part of the TdG (Mid-to-Post), the average flat-equivalent speed was 4.5 km/h and was 37% lower than in [a shorter, 166 km ultramarathon]. Most of the participants were only walking during the final part of the TdG”, the researchers wrote. This involved smaller forces on lower limb muscles, as muscle damage was greater with fast- than slow-velocity eccentric exercise, they said. “Further studies focusing on injuries and pain are required to complete the understanding of the physiological impact of such non-standard exertions”, they wrote.
 

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