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Biomedical subjects

M Pollock

Publications and source records attributed to M Pollock.

At least 55 records · Page 3Linked to original sources
PubMed1982

Effect of heat shock on gene expression in human epidermoid carcinoma cells (strain KB) and in primary cultures of mammalian and avian cells.

The brief incubation of human epidermoid carcinoma (KB) cells, and of primary cultures of quail myoblasts and hamster fibroblasts, at an elevated temperature causes the pattern of gene expression to shift from the production of a broad spectrum of different proteins to the enhanced synthesis of a small number of heat-shock proteins. Comparison of the heat-shock polypeptides synthesized by each of these vertebrate cells demonstrates the similarity of some, as well as the uniqueness of other, heat-inducible gene products synthesized by cells from different vertebrates. A major polypeptide, commonly synthesized in response to heat by each of these vertebrate cells, has an apparent molecular weight of 64 000 and an isoelectric point of 5.8. Triton X-100 completely extracts this polypeptide from quail myoblasts and hamster fibroblasts, and partially extracts it from KB cells. This particular response to heat shock, by cells from different vertebrates, suggests that it may involve the expression of a gene(s) with an analogous and potentially crucial cellular function. This specific heat-shock polypeptide, as well as others, is not detectably synthesized in quail cells prior to heat shock or 6--8 h after recovery from heat shock which suggests that in this cell type it may be a product of a normally quiescent gene(s) and that its expression is subject to thermal regulation.

Animals↗
PubMed1981

Disulfiram neuropathy. A morphometric study of sural nerve.

This report describes peripheral nerve morphology in 3 patients whose acute polyneuropathy followed disulfiram therapy. In all patients a combination of axonal degeneration with segmental demyelination and remyelination was seen, suggesting a varying degree of toxicity to both cytons and Schwann cells. The observed randomness of abnormal internodes argued against primary axonal atrophy and secondary demyelination. While large myelinated fibres were preferentially lost, ultrastructural studies also suggested degeneration of unmyelinated fibres. Because of high chloral consumption at the onset of peripheral nerve disease in 2 patients, the possibility of disulfiram-chloral interaction was considered. Present evidence suggests that the combined use of chloral or its derivatives with disulfiram is best avoided.

Adult↗
PubMed1981

Experimental potassium depletion myopathy.

Myopathic morphological changes were observed in the calf muscles of rats maintained on a potassium-depleted diet for 30-50 days. Light-microscopic changes were more severe in the superficial gastrocnemius muscle fibres and included pallor, swelling and vacuolation, progressing to necrosis, mononuclear cell infiltration and phagocytosis. Mitochondrial disruption, transverse tubular dilatation, membranous body formation and vacuolation were seen on ultrastructural examination. Both vacuoles and subsarcolemmal membranous bodies were shown to be in continuity with the transverse tubular system. More advanced myopathic changes were those of sarcomere destruction and muscle fibre necrosis. Morphological changes resemble those of human potassium depletion myopathy. Ineffective energy metabolism and focal ischaemia due to impaired vasodilatation are proposed as mechanisms for the myopathy of potassium depletion.

Animals↗
PubMed1981

Experimental cold injury to peripheral nerve.

Focal non-freezing injury to rat sciatic nerve resulted in nerve conduction block and cessation of axoplasmic transport. Rats showed early functional recovery but subsequently developed a slowly progressive sciatic nerve paralysis. Horseradish peroxidase studies revealed prominent nerve oedema with early enhanced pinocytosis and later, passive leakage through damaged endoneurial capillaries. Detailed microscopy indicated a striking selective vulnerability to cold based on nerve fibre diameter. Unmyelinated fibres were spared while large myelinated nerve fibres showed severe axonal degeneration. Paranodal and segmental demyelination were infrequent findings and may have resulted from early axonal swelling. Possible pathogenic mechanisms to explain the degeneration of myelinated fibres in hypothermic injury are discussed. It is concluded that the gradient of clinical severity seen in limb hypothermic injuries has a pathological correlate in peripheral nerve.

Animals↗
PubMed1980

Collagen content in human ulnar nerve.

A quantitative analysis of ulnar nerve collagen in the arm and forearm was undertaken in nine subjects. While endoneurial collagen was found to be significantly increased within the cubital tunnel, extrafascicular collagen did not increase at the elbow except in two nerves showing fusiform enlargements. Renaut bodies increased in frequency at sites of high endoneurial collagen content. Morphological determinations of cross-sectional area along the ulnar nerve did not correlate with quantitative collagen data.

Adult↗
PubMed1980

Collagen and protein content of autopsied peripheral nerve.

Rat sciatic nerve was assayed for total collagen and total protein both immediately post-mortem and at weekly intervals after death. No significant difference was found in collagen and protein content between corresponding nerve segments assayed fresh and up to 4 weeks post mortem. However, variation was found in peripheral nerve collagen content between adjacent lengths of sciatic nerve. These results suggest that peripheral nerve collagen and protein remain stable under cool-room conditions for several weeks after death.

Animals↗
PubMed1980

Clinical and morphological features of gold neuropathy.

Three cases of gold-related neuropathy are reported. Clinical features include an acute, symmetrically progressive polyneuropathy, focal or generalized myokymia and a tendency for initial neurological deterioration followed by improvement, after cessation of chrysotherapy. The degree of clinical recovery related to maximal disability. Morphological findings on sural nerve biopsies revealed both axonal degeneration and segmental remyelination. Similar peripheral nerve histology was seen in a parallel animal study in which the severity of the neuropathy was dose-related.

Adult↗
PubMed1979

Identical twins with papilloedema and cranial nerve palsies.

Central nervous system involvement has not been reported previously as a manifestation of sarcoidosis in monozygotic twins. Twin sisters developed multiple cranial nerve palsies and papilloedema within a two month period. Clinical features and the course of their diseases were remarkably similar.

Adult↗
PubMed1977

The analysis of collagen in glutaraldehyde-fixed, osmicated peripheral nerve.

Glutaraldehyde fixation and osmication of rat sciatic nerve and human sural nerve did not appreciably alter the apparent weight of collagen in nerve fasciculi as determined by hydroxyproline analysis of hydrolysed samples. The collagen content of autopsied peripheral nerve is unaltered at least up to 24 h after death. The mean endoneurial weight of collagen per fascicle in rat sciatic nerve was 123 mug (all results expressed for 1 cm length). In human sural nerve the mean weight was 57 mug and the mean fascicular volume 1.75 mm3. Human endoneurial collagen fibrils gave a unimodal distribution of diameters with a peak at 40 nm.

Animals↗
PubMed1977

Peripheral nerve abnormality in multiple sclerosis.

Biopsy specimens of sural nerve from 10 patients with multiple sclerosis (MS), of whom only 1 was severely disabled, were assessed by morphometric techniques and compared to nerves from age-matched controls. The frequency of abnormal teased fibers was increased in MS nerve, with many internodes showing at least a 50% reduction in myelin thickness. Myelinated nerve fiber densities were not significantly different in MS and control nerves. Regression analysis of axonal area on number of myelin lamellae indicated a generalized reduction of myelin lamellae in this disorder. It is suggested that peripheral myelin may be involved in multiple sclerosis.

Axons↗
PubMed1977

The important role of fitness determination and stress testing in predicting coronary incidence.

The question of whether there is some effect of status of cardiorespiratory fitness and exercise ECG abnormalities on occurrence of CHD other than their effect on the risk factors of serum cholesterol, blood pressure, glucose, and smoking seems to have been answered in the affirmative by this study. The relative prognostic importance of the measures considered here, the role of exercise, and the interrelationships between fitness, exercise, other risk factors, and CHD provide many interesting hypotheses for continued study. A future investigation will involve a large prospective study in which the risk function to be derived would include stress ECG and treadmill performance as predictor variables. The retrospective approach reported in this paper had certain limitations. It did, however, permit demonstration of new results because, essentially for the first time, all of the important risk factors are measured in the study population and can be evaluated simultaneously.

Adult↗