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Biomedical subjects

M I McHugh

Publications and source records attributed to M I McHugh.

14 recordsLinked to original sources

In vitro bromodeoxyuridine labelling of renal biopsy specimens: correlation between labelling indices and tubular damage.

AIMS: To examine the correlation between bromodeoxyuridine (BrdU) labelling indices (LI) and tubular damage in renal biopsy specimens; to evaluate the diagnostic and prognostic potential of measuring cell proliferation in a variety of renal lesions. METHODS: In vitro BrdU labelling of renal biopsy specimens was undertaken and labelled cells were detected in routinely fixed, paraffin wax embedded sections by immunohistochemistry. The BrdU LI were calculated as percentages for the three types of tubular cells--proximal and distal convoluted tubules and medulla (LI/PCT, LI/DCT, LI/Med)--and a total tubular BrdU LI (LI/Tub) was also calculated for each biopsy specimen. Histological features indicative of tubular damage were also scored and a total tubular damage score obtained for each biopsy specimen. RESULTS: The one hour labelling process did not affect tissue morphology or impede subsequent diagnosis. Four biopsy specimens were obtained from three renal transplant recipients. Diagnosis of 19 non-transplant biopsy specimens revealed a variety of renal lesions. Total tubular damage scores ranged from 0 to 25 and the LI/Tub ranged from 0 to 3.68% in all 23 biopsy specimens. Analyses of variance showed highly significant correlations between the total tubular damage score and both LI/Tub (p = 0.004) and LI/PCT (p = 0.004); a weaker correlation was found between the total tubular damage score and LI/DCT (p = 0.013). CONCLUSIONS: A correlation was found between tubular damage and BrdU LI. This was most clearly seen in the proximal tubules. However, as the study was limited to a few examples of specific forms of glomerular or interstitial disease, firm conclusions about the value of BrdU labelling in routine diagnosis and prognosis could not be drawn.

Biopsy, Needle↗

The use of a Diasonics DRF400 duplex ultrasound scanner to measure volume flow in arterio-venous fistulae in patients undergoing haemodialysis: an analysis of measurement uncertainties.

A pilot study to measure volume flow in arterio-venous fistulae in patients undergoing haemodialysis was undertaken to determine the accuracy and precision of values obtained using a modern duplex ultrasound scanner. A Diasonics DRF400 duplex ultrasound scanner was used with a small parts 10 MHz mechanical sector probe incorporating a 4.5 MHz Doppler transducer. Volume flow was measured in the brachial artery of 13 patients with surgically created arterio-venous fistulae in the distal circulation. Volume flow was also measured using a flow phantom in which the true volume flow was known. An analysis of the measurements made by the duplex scanner was performed to determine the sources of random and systematic uncertainty. Repeatability was improved with the probe clamped in position over the brachial artery giving a coefficient of variation in repeated measurements of volume flow in a patient of +/- 12%. Measured flows ranged from 884-3088 mL min-1. Comparison with measurements on the flow phantom showed these values from patients to be overestimated by 200-600 mL min-1. The values from the phantom should therefore be used to calibrate patient measurements. Analysis of uncertainties showed that precision was limited by random uncertainties in the measurement of vessel diameter and Doppler angle.

Aged↗

Alternate day steroids and blood pressure control after renal transplantation.

Conversion to alternate day prednisone therapy resulted in a reduction in blood pressure in hypertensive renal transplant recipients. Plasma renin activity was also reduced and may be connected with the fall in blood pressure. There was evidence of increased aldosterone activity, possibly mediated by ACTH, but there was no evidence that the fall in blood pressure was due to changes in sodium status.

Aldosterone↗

Hypertension following renal transplantation: the role of the host's kidney.

Renin, aldosterone and exchangeable sodium were measured in 38 hypertensive and 56 normotensive renal transplant recipients with good renal function and without renal artery stenosis. Response to competitive blockade of angiotensin II using saralasin was studied in 20 of the hypertensive group. Hypertension was uncommon when bilateral nephrectomy had been performed. When diseased kidneys remained in situ, blood pressure after transplantation correlated well with blood pressure on dialysis. Plasma renin activity was higher in hypertensive patients despite higher exchangeable sodium levels. Urinary aldosterone was also higher and correlated well with blood pressure and plasma renin activity. Angiotensin II blockade produced a fall in blood pressure proportional to plasma renin activity. These observations suggest that hypersecretion of renin is an aetiological factor in the hypertension of renal transplant recipients. It appears to act both through the stimulation of aldosterone secretion, with resultant salt retention, and through the direct vasoconstrictor action of angiotensin II. Since renin levels were lower in patients subjected to bilateral nephrectomy the source of the excess renin is probably the host's kidneys.

Adult↗

Immunosuppression with polyunsaturated fatty acids in renal transplantation.

A double-blind controlled trial has been undertaken to assess the value of a preparation containing polyunsaturated fatty acids (PUFA) in human cadaveric renal transplantation. Eighty-nine patients were studied and followed for 6 months after transplantation. Forty-four took the PUFA preparation and 45 the placebo (oleic acid). Other immunosuppression was standardised. Functional graft survival was significantly better in the PUFA group than in those taking the placebo during the first 3 to 4 months post-transplant. At 6 months, however, although the difference between the groups persisted, it was no longer statistically significant. Complications were equally distributed between the groups.

Adult↗