Sunscreen benefits clearly outweigh risks from nanoparticles
Despite concerns over the use of nanoparticles in sunscreens, the proven benefits clearly outweigh the risks, according to an expert opinion in the MJA.
 Professor Paul Wright, from Melbourne’s RMIT, said there was no one-size fits all approach to evaluating the safety of nanotechnology, as various nanoparticles differed greatly in terms of properties such as size, shape and content.
It had been shown that zinc and titanium nanoparticles in sunscreen did not increase levels of free radicals, were well tolerated, and resulted in similar rates of metal absorption as bulk zinc oxide sunscreens, he said.
MJA online; 6 June
ADHD drug, arrhythmia link
The use of methylphenidate (Ritalin) in children and teenagers under 17 years is associated with an increased risk of arrhythmia in the first three days of treatment, a study in the BMJ suggests.
While the absolute risk was low, clinicians should weigh up the risks and benefits of using the drug carefully before prescribing, especially in children with mild ADHD, the authors said.
For myocardial infarction, no increased risk was observed overall, though the risk was significantly raised for exposure up to 56 days only.
No increased risk was seen for hypertension, ischaemic stroke, or heart failure, they said.
BMJ online; 31 May
Quit late in cycle
Women wanting to stop smoking might be more successful if they avoid quitting in the first half of the menstrual cycle, research suggests.
During the early part of the cycle, functional MRI revealed stronger links between the reward centre of the brain and the cortex where decisions were made, the researchers said.
These links enhance responses to smoking cues, such as a coffee break or the smell of a lit cigarette, and spurs women towards, rather than away from, addictive behaviours in the first half of the cycle.
The link was probably due to the lower progesterone-oestrogen ratio at this time.
Biology of Sex Differences online: 31 May
 MRI could replace biopsyÂ
A new type of MRI, restriction spectrum imaging, may hold promise as an “imaging biomarker” to distinguish aggressive prostate cancer from low-grade or benign tumours, researchers say.
The technique can also guide treatment or biopsy to target the region of highest-grade cancer within a tumour.
“Previously, we relied completely on systematic — but random — biopsies of the prostate to diagnose cancer”, the study author said.
The test corrects for magnetic field distortions and can focus water diffusion in tumour cells, which have a high nuclear volume.
Clinical Cancer Research; June 1
