Search PubMed⌕ Search

Biomedical subjects

M Berry

Publications and source records attributed to M Berry.

At least 343 records · Page 19Linked to original sources
PubMed1978

The effects of dark rearing on the development of the visual cortex of the rat.

The effects of dark rearing on the development of the visual cortex has been studied in Wistar rats, as have the effects of subsequent light exposure on recovery. Five groups of animals were used: (1) light exposed until 30-40 days post partum (dpp) (2) dark reared until 30-40 ddp (3) dark reared until 80-120 dpp (4) dark reared to 21 dpp, then light exposed until 40 dpp (5) light exposed to 21 dpp and then dark reared until 40 dpp. Golgi-Cox impregnations of layer IV stellate cell dendritic fields were analysed and total neuronal and glial counts were also done within layer IV of the primary visual cortex. Normal visual stellate cell dendritic fields were radially organised, with the highest dendritic density being recorded below the soma. In short term visually deprived animals and in the exposed only for 21 dpp and then reared in light until 40 dpp the radial distribution of dendrites was maintained but the peak density shifted to above the soma. In all other experimental groups this abnormal polarisation was still present but not as marked. Measurement of branching indices suggested that these field changes resulted from increased branching and growth in the superficial domain and not from the reorientation of dendrites. Differential glial counts revealed a significantly higher number of microglia in dark reared animals than in controls. Neuronal numbers were not affected.

Animals↗
PubMed1978

The effect of refeeding after neonatal starvation on Purkinje cell dendritic growth in the rat.

Male rats, undernourished from birth until 30 days by restricting access to the lactating dam, were given ad libitum food supplies unitl 80 days. Body weight, whole brain weight and cerebellar remained significantly lower in these animals than in normally fed controls. Significant deficits in the area of the molecular and granular layers persisted at 80 days, although there was some recovery during the refeeding period. At the same time granule and Purkinje cell density declined, suggesting that the areal recovery was due to the expansion of the interneuronal matrix. Granule cell numbers remained unchanged between 30 and 80 days. Network analysis of Golgi-Cox preparations indicated a 28% decrease in overall size of the Purkinje cell dendritic networks, due primarily to a deficit in segment frequency which remained unchanged throughout the rehabilitation period. Segment length did, however, show some recovery; distal segments from 80-day experimental networks were significantly longer than those of 30-day undernourished animals. The results of the topological analysis suggested that dendritic remodelling had taken place during the rehabilitation period. The failure to observe a complete recovery in the size and morphology of the dendritic network may be explained in terms of recent suggestions that dendritic development is influenced both by the metabolism of the neurons themselves, and by the number and density of adjacent afferent axons. It is suggested that refeeding from 30 days leads to the recovery of Purkinje cell metabolism, but is unable to restore the parallel fiber deficit.

Animals↗
PubMed1978

Quantitative effects of methylzoxymethanol acetate on Purkinje cell dendritic growth.

A quantitative analysis was made of alterations in the dendritic organisation of Purkinje cells in the cerebellum of the rat following the administration of the degranulating agent, methylazoxymethanol acetate (MAM). This drug depleted the granule cell population of the cerebellar cortex and disturbed Purkinje cell alignment such that a number of Purkinje cells became inverted and grew in the white matter. The quantitative changes that occurred in the dendritic trees of these cells (increase in segment length, decrease in segment numbers, trichotomy and branching probability) were similar to those seen following other degranulation procedures. The size of the Purkinje cell dendritic tree was found to be related to the number of parallel fibres present in the molecular layer. These results were discussed in relation to current theories of neuronal development and were shown to lend further support to the filopodial attachment hypothesis of dendritic growth.

Animals↗
PubMed1978

The effects of undernutrition on Purkinje cell dendritic growth in the rat.

The effects of undernutrition on the developing cerebellum were studied in 30-day-old rats undernourished from birth by restricting access to the lactating mother. These animals showed a significant reduction in cerebellar weight when compared with well-nourished controls. Quantitative studies of the cerebellar vermis revealed a 34.2% reduction in total area, with the density of both granule cells and Purkinje cells increased. Network analysis of Golgi-Cox preparations indicated a significant increase in the density of dendritic fields of Purkinje cells, although there was a 37% decrease in overall network size, due to reduction in the total number of dendritic segments, and a reduction in the length of distal segments. Topological analysis indicated that the network had developed by terminal branching, as in normal animals, but with some deviation from the usual purely random branching pattern. All the observed modifications may be accounted for in terms of alterations in protein synthesis and DNA synthesis occurring in undernourished animals. This leads to alterations in the extent of the interneuronal matrix, a reduction in the number of granule cells and direct effects on Purkinje cell metabolism, all of which influence dendritic development, although the relative importance of each of these factors awaits precise definition.

Animals↗
PubMed1978

[Interest of a combination of film and screen reinforcer in mammography (author's transl)].

The authors present the results of their comparative experimental study on phantoms, of three mammographies. Their study clearly demonstrates the advantages gained by the use of combined film and screen reinforcer compared to classical radiographic procedures using fine-grain film without screen reinforcers. The quality of the images obtained appeared to them to be equal, if not superior, and this seemed to be confirmed by use in clinical practice. Irradiation doses are about one third of the usual dose. They conclude that it would be of value to use mammographs powered by strong generators, as the irradiation dose, under these conditions, would be reduced even further.

Evaluation Studies as Topic↗
PubMed1977

Plasma cholinesterase polymorphism in Down's syndrome.

The plasma cholinesterase variants in 80 patients having Down's syndrome have been examined and compared with a random control sample of individuals domiciled in the same area. Neither a change in frequency of known C5+ variant nor any new variant has been found in the electrophoretic studies. A highly significant increase in frequency of the fluoride resistant gene as well as a significant decrease in frequency of the atypical gene has been found in the Down's syndrome individuals. This altered distribution of the rare phenotype of plasma cholinesterase in mental illness may lead to a useful diagnostic acid in genetic counselling.

Cholinesterases↗
PubMed1977

The plasma cholinesterase variants in mentally ill patients.

The distribution of the plasma cholinesterase variants found in 1,374 mentally ill patients differs from that of a random control sample. The patients are more likely to have a rare phenotype than an individual from the normal population. None of the diagnostic groups have been shown to differ in the distribution of the E1a gene, but there is strong statistical evidence that Group IV (psychosis) patients have a higher frequency of the E1f gene than the other groups. The overall frequency of the electrophoretic variant C5 + did not differ significantly from that observed in a Caucasian population, with the exception of the increase observed in Group IV c2. Twenty-eight unrelated patients with Huntington's chorea were found to have a significantly altered incidence of the C5 + variant and six patients from this group were found to have the rare E1f gene. Our results indicate that the plasma cholinesterase variants may provide some insight into the inheritance of Huntington's chorea.

Bipolar Disorder↗
PubMed1977

Nosocomial infections.

The frequency of nosocomial infection is increasing. The most common sites of such infection are the urinary tract, surgical wounds, the lower part of the respiratory tract, and the skin and subcutaneous tissues. Various techniques are available for prevention of nosocomial infections, but among the most important aspects are understanding and acceptance of responsibility by hospital personnel. The establishment of a surveillance system with a nurse epidemiologist to serve as liaison and educator among professional and ancillary groups within the hospital may be hard to justify on a cost basis to hospital administrators but is important in the control of nosocomial infections.

Bacterial Infections↗