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Biomedical subjects

A H Wilkinson

Publications and source records attributed to A H Wilkinson.

At least 37 records · Page 2Linked to original sources
PubMed1992

The electrophysiologic and histologic effects of the Argon Beam Coagulator on peripheral nerves.

The electrophysiologic and histologic effects of the Bard Argon Beam Coagulator (ABC) were investigated in the New Zealand White rabbit. Thirty-four rabbits were divided into three groups. Controls underwent simple femoral exploration and closure. The remaining rabbits' femoral nerves were spot coagulated with either the ABC or standard electrosurgical unit (ESU). Stimulus thresholds were recorded before treatment and again prior to sacrifice at 0, 30, 60, or 120 days. Thresholds were significantly elevated for the ABC and ESU compared to controls (P = .0077 and .0351, respectively). Changes in threshold were greater for the ABC than for the ESU, but were not significant. All ABC- and ESU-treated nerves had significant histologic injury when compared to controls (P < .0002). Although the ABC may be clinically safe, significant injury to rabbit femoral nerves occurs when they are exposed to energy emitted by this instrument.

Animals↗
PubMed1991

The hepatorenal syndrome in liver transplant recipients.

The hepatorenal syndrome (HRS) is a well-known complication of liver failure, and medical treatment is usually not successful unless liver function can be improved. The authors review their experience with 130 adults undergoing orthotopic liver transplantation (OLT) over a 20-month period to determine the incidence of HRS and its effects on patient outcome, need for hemodialysis (HD), and the degree of recovery of renal function. The clinical diagnosis of HRS preoperatively was made by using criteria to exclude prerenal azotemia, acute tubular necrosis, and primary renal diseases. Nineteen patients were identified as having the HRS for a preoperative incidence of 15.1 per cent. Overall, 41 of the 126 patients reviewed required postoperative HD, and the mortality in this group was 54 per cent. Fifty-eight per cent of the HRS patients were dialyzed postoperatively vs 28 per cent of non-HRS patients. The mean posttransplant creatinine improved over time in the HRS patients while it worsened slightly in the non-HRS group. At 12 weeks posttransplant, there was a significant difference in the mean creatinine levels (1.8 +/- 0.3 mg/dl vs 1.2 +/- 0.04 mg/dl, P = .001). However, at 24 weeks the small difference was not statistically significant between the two groups (1.6 +/- 0.15 mg/dl vs 1.3 +/- 0.06 mg/dl, P = NS). The current survival of the hepatorenal group is comparable to the nonhepatorenal patients at a follow-up of 6 to 25 months: 68 per cent vs 78 per cent, P = NS. The authors conclude that liver transplantation reverses the HRS, and that hepatorenal patients can undergo liver transplantation with outcomes comparable to nonhepatorenal patients.

Cause of Death↗
PubMed1989

Increase in proteinuria and reduction in number of anionic sites on the glomerular basement membrane in rabbits by infusion of human nephrotic plasma in vivo.

1. Intraortic suprarenal infusion in vivo of New Zealand White rabbits with plasma from patients with the nephrotic syndrome reduced the number of anionic sites labelled by the cationic polymer polyethyleneimine in the lamina rara iterna to 14.0 +/- 2.7 per 1000 nm of lamina rara interna (mean +/- SD) compared with 18.7 +/- 2.1 (P less than 0.005) after infusion of plasma from normal subjects. 2. Proteinuria increased in all nine animals infused with nephrotic plasma and in two of seven infused with control plasma (P less than 0.01). The mean increase in proteinuria in the animals infused with nephrotic plasma was 246 mg/l (P less than 0.05), whereas in those infused with control plasma there was no increase. 3. We conclude that nephrotic plasma contains a factor(s) capable of neutralizing the charge of these anionic sites and concomitantly increasing proteinuria.

Animals↗
PubMed1989

Increased frequency of posttransplant lymphomas in patients treated with cyclosporine, azathioprine, and prednisone.

We have documented seven B cell lymphomas over a six-month period in 132 (5.3%) kidney and heart allograft recipients immunosuppressed with cyclosporine, azathioprine, and prednisone (triple therapy). This is a significant increase (P less than 0.0001) over the number of such tumors seen by us previously. Only 2 lymphomas had occurred in 669 cadaver and 29 living-related kidney allografts treated with azathioprine and prednisone alone (0.3%). In 160 cadaver kidney recipients treated with cyclosporine and prednisone there have been no lymphomas. Similarly in 14 living-related kidney recipients who were transplanted since the introduction of triple therapy for cadaver grafts, but continued to receive only azathioprine and prednisone, no lymphomas occurred. There seemed to be a clear relationship between this increase and the use of triple therapy. This led us to examine other possible contributing factors. A case control study has not shown any other factor that differs in patients in whom lymphomas developed. We have only been able to demonstrate Epstein Barr virus nuclear antigen in the cells of one tumor. Four of these 7 tumors were monoclonal, one polyclonal, and two indeterminate. All patients had their immunosuppression withdrawn and six received intravenous acyclovir. Three patients have shown some response but four patients died. Triple therapy is being used by many centers to reduce the level of cyclosporine toxicity. We wish to sound a note of caution that this may result in an increased incidence of posttransplant lymphomas.

Adult↗
PubMed1985

Cardiovascular and hormonal effects of clonidine in patients with essential hypertension and renal hypertension.

The putative role of the central nervous system in the maintenance of elevated blood pressure in patients with essential hypertension (EH) and renal hypertension [unilateral renal parenchymal disease (RPD) and unilateral renal artery stenosis (RAS)] was studied by investigating the cardiovascular and hormonal effects of the predominantly centrally acting sympatholytic agent, clonidine. Oral clonidine lowered blood pressure substantially in all three groups. Levels of plasma renin activity were unchanged in EH and RAS but progressively fell in RPD. Plasma noradrenaline levels fell in all three groups. Clonidine therefore reduced blood pressure to the same extent in three distinct groups of hypertensives, in two of which the initiating cause was undoubtedly renal. This indicates that, although the primary cause differed, a prominent factor sustaining hypertension may have been an increase or an inappropriate maintenance of central pressor mechanisms.

Adult↗
PubMed1983

Clonidine in unilateral renal artery stenosis and unilateral renal parenchymal disease--similar antihypertensive but different renin suppressive effects.

The effects of 300 micrograms oral clonidine were studied in 15 hypertensive patients with unilateral renal involvement -nine had renal artery stenosis and six renal parenchymal disease. After clonidine blood pressure fell substantially in both groups, with the maximum fall in the fourth hour and effects persisting after 6 h. Levels of plasma renin activity were considerably higher in the renal artery stenosis patients and remained unchanged during the study; there was a progressive fall in levels in each of the patients with renal parenchymal disease. Plasma noradrenaline levels fell in both groups. Clonidine therefore lowers blood pressure in patients with unilateral renal artery stenosis and renal parenchymal disease. The known pharmacological effects of clonidine would thus favour either an increase or an inappropriate maintenance of central pressor activity as a contributory factor to the hypertension in both groups. The central mechanisms raising blood pressure may result not only from high angiotensin II levels but to other less well defined effects, from an ischaemic or diseased kidney. The lack of fall of plasma renin activity in the renal artery stenosis patients probably indicates the greater influence of ischaemia and renal baroreceptor stimulation over sympathetically mediated renin release.

Adolescent↗
PubMed1982

Mycobacterial lymphadenitis.

The plan for cervical lymph node biopsy should include special maneuvers for recognition of patients with lymphadenitis due to atypical mycobacteria, since these children need extensive operations. The diagnosis should be suspected in children less than 3 yr old with lymphadenopathy present for several months and no exposure to cats (or with negative cat scratch skin tests). Wide local excision of all visibly involved nodes is recommended; acid-fast touch preparations should be done and interpreted during operation in any suspicious case. Limited operations should be avoided in children with mycobacterial lymphadenitis. The illness may be more common than previously suspected.

Cat-Scratch Disease↗
PubMed1982

Protection of the solitary testis.

In 15 negative explorations for unilateral cryptorchidism, inspection of the contralateral scrotum revealed a "bell-clapper" deformity in 13 patients. Since the descent of the testis is influenced by the gubernaculum and gubernacular abnormalities are usually bilateral, the data suggest that an inadequate gubernaculum is associated with most instances of antenatal and postnatal torsion. Unilateral absence of the testis is a form of this syndrome; congenital monorchidism is probably due to antenatal torsion rather than hypoplasia or agenesis. When monorchidism is confirmed at operation, exploration and suture fixation of the contralateral testis at the same procedure is recommended to protect the solitary testis from future torsion.

Adolescent↗
PubMed1977

Radioisotope diagnosis of splenic trauma.

Multiple injury or delay in seeking medical attention may prevent confident clinical diagnosis of splenic trauma. The spleen scan is a rapid, simple, noninvasive test useful in such circumstances. When peritoneal lavage is contraindicated, unrevealing, or inapproapriate, radioisotope imaging of the spleen can help confirm a suspicion of splenic injury.

Adolescent↗