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Biomedical subjects

G C Mason

Publications and source records attributed to G C Mason.

10 recordsLinked to original sources
PubMed1988

Poor maternal weight gain between 28 and 32 weeks gestation may predict small-for-gestational-age infants.

In a retrospective analysis of 158 women considered to have had normal, low-risk pregnancies, 30 gave birth to infants with a birthweight less than the 10th centile for gestation. These 30 women had a significantly poorer mean increase in weight (0.99 kg) between 28 and 32 weeks gestation than the other 128 women (1.95 kg) who gave birth to infants with birthweights above the 10th centile for gestation. There was no statistically significant difference in booking weight, overall weight gain or other variables associated with low birthweight between the two groups of women which suggests that poor maternal weight gain specifically between 28 and 32 weeks gestation may predict small-for-gestational-age infants.

Adult↗
PubMed1986

Accuracy and reproducibility of a new contrast clearance method for the determination of glomerular filtration rate.

A new method for determining the glomerular filtration rate was analysed prospectively. The method uses an x ray fluorescence technique to measure disappearance from the plasma of injected non-ionic iodinated contrast media. Eighty seven patients were studied. Fifty four had an intravenous dose of 100 ml iohexol (Omnipaque) and 33 had 50 ml iohexol. Clearances of chromium-51 labelled edetic acid (51Cr-EDTA) were measured simultaneously. In the patients given 100 ml iohexol there was excellent correlation with 51Cr-EDTA clearance (r = 0.90). The correlation using 50 ml iohexol was also good (r = 0.85). Correlation between creatinine clearance and clearance of 51Cr-EDTA in 33 patients was less satisfactory (r = 0.69). There were no adverse reactions to the contrast media. The equipment used for measuring contrast clearance was robust and simple to operate. Freezing plasma samples in 10 studies and re-examining them weekly for six weeks showed no significant variation in results; hence reproducibility was good. This new and accurate method for determining the glomerular filtration rate merits further study and might find a useful place in routine clinical practice.

Adolescent↗
PubMed1986

Studies on the stimulation of the bacterial, collagenolytic enzyme clostridiopeptidase A by cobalt (II) ions.

Co(II) ions increase the Vmax of clostridiopeptidase A, producing a maximum stimulation of overall enzymic activity of 120%. Co(II) does not displace Zn(II) from the active site, nor Ca(II) from its binding site on the enzyme. There appears to be an additional transition metal-binding site on clostridiopeptidase A, accepting Zn(II), which is inhibitory (Ki = 550 microM), or Co(II), which is stimulatory (Kact = 200 microM).

Cobalt↗
PubMed1986

High pressure chronic retention. Incidence, aetiology and sinister implications.

A prospective analysis of 36 consecutive cases of high pressure chronic retention presenting over a 3-year period is described. Thirty-nine per cent of patients had malignant prostates and 14% had bladder tumours (overall malignancy rate 53%). The dangers of mismanagement of high pressure chronic retention include uraemic death and hypovolaemic circulatory collapse from neglected post-obstructive diuresis. The clinician should be prepared to find a high incidence of urological malignant disease in patients presenting with this syndrome.

Aged↗
PubMed1986

Does ovarian sex cord tumour with annular tubules produce progesterone?

Probable progesterone production was identified by an immunoperoxidase assay in a case of an ovarian sex cord tumour with annular tubules. The tumour was associated with a serous cystadenofibroma in the opposite ovary and with adenoma malignum (adenocarcinoma) of the cervix.

Adenocarcinoma↗
PubMedDate not supplied

The biochemical and histological effects of artificial ligament wear particles: in vitro and in vivo studies.

Growing evidence suggests that biochemical mechanisms play a role in the pathogenesis of arthritis. Cartilaginous wear particles have been shown to induce destructive enzymes and cytokines. To assess the biocompatibility of artificial ACL replacements, the effects of wear particles from the following ligaments were analyzed biochemically and histologically: GORETEX, Stryker Dacron Ligament Prosthesis, Versigraft carbon, Kennedy LAD, Xenograft, Leeds-Keio, and human patellar tendon allograft. Ligaments were frozen and ground to produce wear particles similar to those seen clinically and were added to lapine synovial cell cultures. The resulting conditioned medium was analyzed for collagenase, gelatinase, and chondrocyte activating factor (CAF) production. All of the ligaments induced significantly elevated enzyme and CAF production by the synoviocytes, with Xenograft and carbon inducing significantly higher enzyme levels than those of the other five ligaments. Five milligrams of wear particles were injected into the knees of 4 kg to 5 kg rabbits that were analyzed histologically after 14 weeks. Wear particles accumulated in the periarticular synovial folds and induced modest to severe macrophage infiltration in the synovium. A hypothetical model explaining the role of artificial ligament wear particles in the pathogenesis of arthritis is presented.

Animals↗
PubMedDate not supplied

Cidex-induced synovitis.

Microscopic evidence of inflammation was observed in the synovium of rabbit knees that had been injected with 10 ppm of Cidex (2% glutaraldehyde). Initial changes were synovial hypertrophy, subsynovial edema, and vascular congestion. At concentrations of 100 ppm or greater, focal synovial necrosis, hemorrhage, and gross diffuse synovitis were observed. The degree of synovial inflammation was proportional to the concentration of Cidex. Observation of synovial response versus time demonstrated this reaction to be a chemical synovitis without histologic evidence of a delayed hypersensitivity allergic component. Significant intraoperative levels of Cidex were noted in the rise solutions at several hospitals. When a single rinse is used, the concentration of Cidex present in the rinse basin is 100 to 300 ppm. If the same rinse is used for subsequent cases, the Cidex concentration is on the order of 1,000 ppm by the fifth arthroscopic procedure. If a double rinse is used and the rinse changed with each operative case, the Cidex concentration in the second rinse is less than 10 ppm. After irrigation of the knee joint with 1 liter of saline, the intraarticular concentration of Cidex is less than 10 ppm regardless of the rinse technique.

Aldehydes↗