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Biomedical subjects

W Harvey

Publications and source records attributed to W Harvey.

At least 73 records · Page 4Linked to original sources
PubMed1982

A biochemical and immunohistological study of collagen synthesis in Ewing's tumour.

The synthesis and localization of collagen have been studied on material from a total of 16 primary Ewing's tumours. The predominant collagen extracted from the tissues and synthesized in short-term cultures was type I. The proportion of type III collagen was relatively small and variable (0-8%) in the direct tumour extracts, but a higher proportion (29-38% of the total collagens) was synthesized in culture. Immunofluorescence studies showed that positive staining for all types of collagen tested (types I, III, IV and V) was restricted to stroma; there was no evidence of collagen either within the tumour cells or in their pericellular matrix, a finding endorsed by negative staining for reticulin in the same areas. The absence of any evidence for type IV or V collagen synthesis by Ewing's cells argues against an endothelial origin for the tumour, and indicates that collagen analysis is unlikely to be of value in the diagnosis of this particular sarcoma.

Bone Neoplasms↗
PubMed1982

Chromatin-associated deoxyribonuclease activity in liver nuclei isolated from Rana catesbeiana froglets and premetamorphic and T3-induced tadpoles.

Nuclei and chromatin isolated in the presence of calcium or magnesium from Rana catesbeiana liver tissue exhibit considerable endogenous deoxyribonuclease activity. This activity is present in liver nuclei isolated from froglets as well as in liver nuclei isolated from untreated and thyroid hormone treated premetamorphic tadpoles. Nuclei and chromatin isolated in the absence of divalent cations and in the presence of spermine exhibit no detectable expression of the endogenous deoxyribonuclease activity. The endogenous deoxyribonuclease present, but not expressed, in spermine-isolated tadpole liver nuclei or chromatin is salt extractable. Once dialyzed, the salt-extracted deoxyribonuclease is activated by calcium or magnesium. This deoxyribonuclease shows maximal enzyme activity in 15 mM calcium at pH 8.0 or in 15 mM magnesium at pH 7.4. After Ca2+ activation, deoxyribonuclease activity is maximally inhibited by amounts of spermine similar to that required to completely inhibit DNase I. Destruction of the salt-extracted deoxyribonuclease activity by treatment with proteinase K or heat suggests that it is of a proteinaceous nature. The localization and nature of this enzyme activity established that it is associated with the salt-soluble proteins affiliated with tadpole and froglet liver chromatin.

Animals↗
PubMed1981

A clinical and echocardiographic study of patients with the hypermobility syndrome.

Three age- and symptom-matched groups of patients with a hypermobility score of 5-9, 3-4, and 0-2 (controls), respectively, were examined for clinical and echocardiographic evidence of mitral valve prolapse and other stigmata of a collagen disorder. Mitral valve prolapse, a reduced upper segment/lower segment mitral ratio, reduced skin thickness, spinal anomalies, and a history of fracture were found to be significantly commoner among the hypermobile patients than the controls. The data suggest that the so-called hypermobility syndrome, far from being a benign locomotor disorder of healthy persons, may be a forme fruste of a hereditary disorder of connective tissue.

Adult↗
PubMed1981

The aetiology of oral submucous fibrosis: the stimulation of collagen synthesis by extracts of areca nut.

Oral submucous fibrosis is a chronic disabling disease developing in up to 0.5% of the estimated 500 million habitual chewers of the "betel" quid. The quid, or chew, usually comprises a leaf of the Piper betel vine in which is wrapped fragments of the nut of Areca catechu, together with slaked lime and varied additives, including tobacco. The precise aetiology of oral submucous fibrosis (OSF) remains obscure, but epidemiological and animal studies have pointed to a close association with the prolonged usage of A. catechu nuts. Epithelial atypia and epidermoid carcinoma have been reported in 15% and 7%, respectively, of patients with established OSF. Preparations from varieties of A. catechu nuts have been tested for their ability to stimulate collagen synthesis in microwell cultures of human fibroblasts, using a pulse of 3H-proline and subsequent analysis of the cultures for radioactive collagen. Crude extracts of three varieties of areca nuts were extracted with ethanol and lyophilised before dilution in the culture medium. Control media contained identical concentrations of ethanol where appropriate. The three extracts at a concentration of 10 micrograms/ml stimulated collagen synthesis by approximately 150%, suggesting that this effect might be involved in the aetiology of oral submucous fibrosis.

Areca↗
PubMed1980

The role of ultrasound-induced cavitation in the 'in vitro' stimulation of collagen synthesis in human fibroblasts.

Collagen synthesis by human embryonic fibroblasts in vitro was estimated using a collagenase-sensitivity assay. Collagen synthesis was stimulated by irradiation with ultrasound at a frequency of 3 MHz, a space-time peak intensity of 0.5 Wcm-2, pulsed at a mark-space ratio of 2:8 ms for 5 min at ambient pressure. This stimulation was suppressed by the application of a positive pressure of 2 atmospheres during irradiation of the cells. Increasing the pressure in the absence of ultrasound had no effect on the rate of collagen synthesis in control cells. This stimulation, therefore, appears to be due to ultrasound-induced cavitation, since it is unlikely that increasing the pressure could modify any other ultrasonic parameter. Collagen synthesis is apparently stimulated to the same extent as general protein synthesis.

Acoustic Stimulation↗
PubMed1976

Effects of steriod hormones on human fibroblasts in vitro. II. Antagonism by androgens of cortisol-induced inhibition.

Inhibition of dermal activity by cortisol in culture was partially reversed by two naturally occurring androgens, testosterone and dihydrotestosterone. ACTH and the androgen precursor dehydroepiandrosterone sulphate showed not such antagonistic effect. These results suggest that increased production of adrenal androgens during ACTH therapy may account for the relative absnece of 'skin-thinning' and 'steroid-bruising' which are common side-effects of corticosteroid therapy.

Adrenocorticotropic Hormone↗
PubMed1975

Cutaneous extensibility in health and disease.

The results are recorded of a number of studies performed over the last few years using a simple and reproducible method for investigating the extensibility of intact skin. A major advantage of this method lies in the fact that it causes the patient no discomfort and leaves his skin without blemish. We have found abnormal behaviour of skin in response to applied stress in the heritable connective tissue disorders: Ehlers-Danlos Syndrome, cutis laxa, and pseudoxanthoma elasticum, and in the acquired disorders of acromegaly, hypopituitarism and scleroderma. An abnormal elastic modulus, however, was found only in pseudoxanthoma elasticum and the growth-hormone disorders.

Acromegaly↗
PubMed1975

Cutaneous extensibility in pseudo-xanthoma elasticum.

In vivo skin elasticity was measured on unaffected forearm skin of twenty-five patients with pseudo-xanthoma elasticum and compared with age and sex-matched controls. The elastic modulus was raised in the recessive type I group and reduced in the dominant types I and II groups. No significant difference in skin thickness was found.

Adult↗
PubMed1975

Survey of joint mobility and in vivo skin elasticity in London schoolchildren.

A survey of joint mobility was conducted in 295 healthy children between the ages of 5 and 10 years who attended a London primary school. Estimates of the commonly used measurements, that is passive dorsiflexion of the wirsts and ankles, passive hypertension of the elbows and knee, were too insensitive to detect any age effect. However, a method of estimating extensibility of the 5th metacarpophalangeal joint in response to a standard load detected a highly significant inverse correlation between joint mobility and age in the samples significant inverse correlation between joint mobility and age in the samples tested ( r = -0.586; P less than 0.0001). There was no apparement sex difference. Skinfold thickness using the Harpenden caliper over the 3rd metacarpal bone and the in vivo skin elasticity measured using a suction cup device performed on a sample of 78 of the children revealed no influence of either age or sex on these parameters. This is in sharp contradistinction to the effect of both age and sex in these two parameters in adults...

Age Factors↗