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Biomedical subjects

N T James

Publications and source records attributed to N T James.

At least 55 records · Page 3Linked to original sources
PubMed1980

Quantitative studies on the contiguity of muscle fibre types in normal and hypertrophic skeletal muscles.

Skeletal muscles consist of an heterogeneous population of muscle fibres. A method for deriving an index of contiguity for any of the fibre types is proposed. This term is defined as the proportion of the total boundary length (interface) of a fibre type which is in contact with fibres of the same type. It can be measured on any type of skeletal muscle independently of its composition. Values for the index of contiguity for the two major types of fibre in normal and hypertrophic extensor digitorum longus muscles of the mouse do not seem to differ.

Animals↗
PubMed1979

Ultrastructure of muscle spindles in C57BL/6J dy2J/dy2J dystrophic mice.

The sensory organs of skeletal muscles, the muscle spindles, were examined using electron microscopy in dy2J/dy2J dystrophic mice. Despite widespread damage to the extrafusal (skeletomotor) fibres the intrafusal (spindle) fibres appeared normal and seemed resistant to the aetiological factors for murine dystrophy.

Animals↗
PubMed1979

Stereological analyses of the structure of mitochondria in pigeon skeletal muscle.

The mitochondria in type-I and -II muscle fibres in the pectoralis major muscle of the pigeon (Columba livia) have been analysed using stereological techniques not previously applied in muscle biology. Mitochondrial volume fractions (VV) were estimated in different regions of each type of muscle fibre using randomly orientated sampling sectors within fibre profiles. These sectors were sub-divided into smaller sampling regions to provide accurate data on the intracellular distribution of mitochondria. Estimates of the external surface densities of mitochondria per unit volume of fibre, SV total surface, and also the densities of mitochondrial cristae, SV total cristae, were obtained using a specific technique derived for analysing anisotropic structures (Saltykov, 1958). The relative amounts of the random and orientated mitochondrial membranes were also estimated. Significant differences were found to exist between the different types of muscle fibres and considerable though constant variations in the intracellular arrangement of mitochondria were also found.

Animals↗
PubMed1979

Studies on the responses of different types of muscle fibre during surgically induced compensatory hypertrophy.

The sizes of the different types of muscle fibre in the extensor digitorum longus (EDL) muscles of mice have been measured, EDL muscles showing compensatory hypertrophy following the removal of the tibialis anterior muscle 116 days previously being compared with normal contralateral controls. Contrary to previous findings, the hypertrophy was well maintained after 116 days and Type II fibres were enlarged preferentially.

Animals↗
PubMed1978

A stereological analysis of the effect of 19-nortestosterone (Durabolin) on rat skeletal muscle.

It is known that some anabolic steroids are capable of increasing the sizes of skeletal muscles or increasing their mechanical performance. The present study was undertaken to establish quantitatively the alterations which occur in skeletal muscle fibres as a result of the injection of 19-nortestosterone (nandrolone phenyl proprionate). Specimens of diaphragm were obtained from the experimental and control animals and prepared for electron microscopy and stereological analyses. Following low doses of the steroid stereological analyses have shown that in Type I and in intermediate fibres their mitochondrial volume proportions increase though their myofilament contents decrease. With higher doses, stereological analyses have shown that the mitochondrial volume proportions were increased particularly in intermediate fibres whilst the myofilament content of Type I and II fibres was significantly reduced.

Animals↗
PubMed1976

Compensatory muscular hypertrophy in the extensor digitorum longus muscle of the mouse.

Hypertrophy of the extensor digitorum longus muscle after surgical removal of its companion tibialis anterior muscle has been studied in mice. Early, intermediate and late stages in the process of hypertrophy have been defined. The proportional increase in the man cross sectional area of fibres in a hypertrophic muscle consistently exceeded the proportional increase in the weight of the same muscle in all animals. This suggests that hypoplasis (loss of fibres) was occurring. This work was carried out with the aid of grants from the Medical Research Council and Science Research Council of Great Britain.

Animals↗