The timing of eruption of the primary dentition in Nigerian children

The objectives of this study were to clarify the eruption time and sequence for primary teeth in Nigerian children. It also investigated the effect of sex and socioeconomic status on the timing and sequence of eruption. A random sample of 1,657 children from ages of 3-40 months were examined--921 (55.6%) males and 736 (44.4%) females. The age of eruption of the teeth was estimated using probit regression. The results show that there was no effect of sex, socioeconomic status or breastfeeding status on the timing of eruption and pattern of teeth eruption in Nigerian children. Left and right teeth had similar eruption times. Eruption times of the lateral incisor, canine, and molars were similar for upper and lower teeth. Interpopulation studies however showed that though the sequence of eruption of primary teeth in Nigerian population is similar to that of their peers in other compared populations, there are observable sex differences in the timing of tooth eruption.     

The costs of being a restless intellect: Julian Huxley’s popular and scientific career in the 1920s

Julian Huxley’s (1887–1975) contribution to twentieth-century biology and science popularisation is well documented. What has not been appreciated so far is that despite Huxley’s eminence as a public scientific figure and the part that he played in the rise of experimental zoology in Britain in the 1920s, his own research was often heavily criticised in this period by his colleagues. This resulted in numerous difficulties in getting his scientific research published in the early 1920s. At this time, Huxley started his popular science career. Huxley’s friends criticised him for engaging in this actively and attributed the publication difficulties to the time that he allocated to popular science. The cause might also have its roots in his self-professed inability to delve deeply into the particularities of research. This affected Huxley’s standing in the scientific community and seems to have contributed to the fact that Huxley failed twice in the late 1920s to be elected to the Royal Society. This picture undermines to some extent Peter J. Bowler’s recent portrayal of Huxley as a science populariser.     

The Social Amoeba Dictyostelium discoideum Is Highly Resistant to Polyglutamine Aggregation

The expression, misfolding, and aggregation of long repetitive amino acid tracts are a major contributing factor in a number of neurodegenerative diseases, including C9ORF72 amyotrophic lateral sclerosis/frontotemporal dementia, fragile X tremor ataxia syndrome, myotonic dystrophy type 1, spinocerebellar ataxia type 8, and the nine polyglutamine diseases. Protein aggregation is a hallmark of each of these diseases. In model organisms, including yeast, worms, flies, mice, rats, and human cells, expression of proteins with the long repetitive amino acid tracts associated with these diseases recapitulates the protein aggregation that occurs in human disease. Here we show that the model organism Dictyostelium discoideum has evolved to normally encode long polyglutamine tracts and express these proteins in a soluble form. We also show that Dictyostelium has the capacity to suppress aggregation of a polyglutamine-expanded Huntingtin construct that aggregates in other model organisms tested. Together, these data identify Dictyostelium as a novel model organism with the capacity to suppress aggregation of proteins with long polyglutamine tracts.     

The effect of valinomycin in fibroblasts from patients with fatty acid oxidation disorders

Disorders of the carnitine cycle and of the beta oxidation spiral impair the ability to obtain energy from fats at time of fasting and stress. This can result in hypoketotic hypoglycemia, cardiomyopathy, cardiac arrhythmia and other chronic medical problems. The in vitro study of fibroblasts from patients with these conditions is impaired by their limited oxidative capacity. Here we evaluate the capacity of valinomycin, a potassium ionophore that increases mitochondrial respiration, to increase the oxidation of fatty acids in cells from patients with inherited fatty acid oxidation defects. The addition of valinomycin to fibroblasts decreased the accumulation of the lipophilic cation tetraphenylphosphonium (TPP⁺) at low concentrations due to the dissipation of the mitochondrial membrane potential. At higher doses, valinomycin increased TPP⁺ accumulation due to the increased potassium permeability of the plasma membrane and subsequent cellular hyperpolarization. The incubation of normal fibroblasts with valinomycin increased [¹⁴C]-palmitate oxidation (measured as [¹⁴C]O₂ release) in a dose-dependent manner. By contrast, valinomycin failed to increase palmitate oxidation in fibroblasts from patients with very long chain acyl CoA dehydrogenase (VLCAD) deficiency. This was not observed in fibroblasts from patients heterozygous for this condition. These results indicate that valinomycin can increase fatty acid oxidation in normal fibroblasts and could be useful to differentiate heterozygotes from patients affected with VLCAD deficiency.     

The Plymouth Laboratory and the Institutionalization of Experimental Zoology in Britain in the 1920s

The Plymouth Laboratory of the Marine Biological Association of the United Kingdom (1884) was founded in 1888. In addition to conducting morphological and other biological research, the founders of the laboratory aimed at promoting research in experimental zoology which will be used in this paper as a synonym for e.g. experimental embryology, comparative physiology or general physiology. This dream was not fully realized until 1920. The Great War and its immediate aftermath had a positive impact on the development of the Plymouth Laboratory. The war greatly upset the operation of the Zoological Station in Naples and the ensuing crisis in its operations was closely related to the establishment of the physiological department in Plymouth in 1920. Two other key factors in the Plymouth story were the establishment of the Development Fund in 1909, which began contributing funds to the Plymouth Laboratory in 1912, and the patronage of the Cambridge zoologist George P. Bidder (1863–1954). This paper will focus on the combined influence of the Development Fund and Bidder on the development of the Plymouth Laboratory from around 1902 through the early 1920s, and the important role the laboratory played in promoting experimental zoology in Britain in the 1920s.