Neuroscience in the public sphere

The media are increasingly fascinated by neuroscience. Here, we consider how neuroscientific discoveries are thematically represented in the popular press and the implications this has for society. In communicating research, neuroscientists should be sensitive to the social consequences neuroscientific information may have once it enters the public sphere.     

Fetal and infant head circumference sexual dimorphism in primates

Studies have shown that after controlling for the effects of body size on brain size, the brains of adult humans, rhesus monkeys, and chimpanzees differ in relative size, where males have a greater volume of cerebral tissue than females. We assess whether head circumference sexual dimorphism is present during early development by evaluating sex differences in relative head circumference in living fetuses and infants within the first year of life. Head circumference is used as a proxy for brain size in the fetus and infant. Femur length is used as a proxy for body length in the fetus. Ultrasonography was used to obtain fetal measures, and anthropometry was used to obtain postnatal measures in humans, rhesus monkeys, baboons, and common marmosets. We show that statistically significant but low levels of head circumference sexual dimorphism are present in humans, rhesus monkeys, and baboons in early life. On average, males have head circumferences about 2% larger than females of comparable femur/body length in humans, rhesus monkeys, and baboons. No evidence for head circumference sexual dimorphism in the common marmoset was found. Dimorphism was present across all body size ranges. We suggest that head circumference sexual dimorphism emerges largely postnatally and increases throughout maturation, particularly in humans who reach adult dimorphism values greater than the monkeys. We suggest that brain dimorphism is not likely to impose an additional energetic burden to the gestating or lactating mother. Finally, some of the problems with ascribing functional significance to brain size sexual dimorphism are discussed, and the energetic implications for brain size sexual dimorphism in infancy are assessed.     

Metabolic Responses to Oral Glucose in the Kalahari Bushmen

The plasma glucose, immunoreactive insulin, and growth hormone levels after a 50-g oral glucose load have been measured in 15 adult Bushmen subjects living in the Kalahari region of Southern Africa. Compared with 10 non-obese white controls, they showed relative glucose intolerance and significantly impaired insulin secretion. Growth hormone responses showed no significant differences between the two groups. Factors such as inadequate or unusual nutrition and stress do not appear to account completely for the abnormalities in carbohydrate metabolism observed in the Bushmen. Of interest are the clinical and hormonal similarities that seem to exist between the Bushmen and the Central African Pygmies.     

Comparison of the effects of Altozar and DDT on females ofIxodes persulcatus Sch. during and after feeding

Ixodes persulcatus females were treated with Altozar and DDT at one of six consecutive time-points during the period beginning with attachments and ending with the commencement of oviposition.The moment of tick attachment (point 1) appeared to be the most sensitive time for the action of Altozar; a delay of detachment of some of the engorged females was observed, as well as a decrease in their mean weight and the non-detachment of a considerable number of the females over a long period. Similar effects were observed when Altozar was applied on the first and third days after attachments (points 2 and 3) although in the first case they were less pronounced. Altozar treatments on the fifth day of feeding, shortly before oviposition, and especially immediately after detachment (points 4,5 and 6, respectively) mainly resulted in non-viability of the eggs.DDT was ineffective when it was applied at point 1. DDT treatments of ticks at points 3 and 5 were highly effective; this was expresseds by a reduction in weight of the engorged females and a suppression of their fecundity at point 3, and death of all the larvae at different times after hatching at point 5. Many larvae also perished when the ticks were treated with DDT at point 6. Ticks were quite tolerant to DDT action when they were treated at points 2 and 4.The action of both compounds ultimately resulted in the inhibition of tick reproduction, but the rate and method depended on the compound applied as well as on the time of treatment. Altozar effects after treatment at points 1–3 may be considered to be hormonal.     

5S rRNA sequences of 12 species of flatworms: implications for the phylogeny of the Platyhelminthes

5S rRNAs from 12 species of free living and parasitic platyhelminthes were sequenced. In the phylogenetic analysis, attention was focused on the statistical estimates of the trees corresponding to existing phylogenetic hypotheses. The available 5S rRNA data agree well with widely accepted views on the relationships between the Acoela, Polycladida, Tricladida, and Neorhabdocoela; our analysis of the published 18S rRNA sequences also demonstrated good correspondence between these views and molecular data. With available 5S rRNA data the hypothesis that the dalyellioid turbellarians is the sister group of the Neodermata is less convincing than the hypotheses proposing the Neodermata as the sister group of the Neorhabdocoela, or of the Seriata, or of the branch uniting them. A relatively low rate of base replacement in parasitic flatworms, probably, accounts for the uncertain position of the Neodermata, while a relatively high rate in planarians may explain a relatively too early divergence of the Tricladida in several published phylogenetic trees constructed from various rRNA data.     

Neodymium yttrium aluminium garnet laser photocoagulation for major haemorrhage from peptic ulcers and single vessels: a single blind controlled study.

A prospective single blind controlled trial was performed to assess the efficacy of the neodymium yttrium aluminium garnet laser in the management of patients bleeding from peptic ulcers and single vessels. Over 20 months 184 patients were found at endoscopy to be bleeding from peptic ulcers and single vessels; 130 of these failed to meet the criteria for entry into the study, but their bleeding stopped with conservative management. Forty-five patients entered the study: in all 25 who were bleeding from ulcers with spots the bleeding stopped irrespective of the treatment allocated. Twenty patients were bleeding from arteries. Eight were allocated to placebo treatment, and all later underwent emergency surgery for further haemorrhage. Twelve were allocated to receive laser treatment, and only one of eight who actually received it required surgery (p less than 0.002). It is concluded that laser treatment reduces the incidence of further haemorrhage and the need for emergency surgery, but the technique is difficult and not always applicable.