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Biomedical subjects

A D Barnes

Publications and source records attributed to A D Barnes.

At least 19 recordsLinked to original sources
PubMed2001

Metabolic and hormonal effects of tacrolimus (FK506) or cyclosporin immunosuppression following renal transplantation.

Twelve renal transplant recipients randomised to receive immunosuppression with either tacrolimus (FK506) or cyclosporin underwent oral glucose tolerance tests (OGTT) a median of 8 months (range 7-9) after transplantation. Six healthy subjects acted as controls. Compared with the controls, both transplant groups had significantly elevated fasting (p < 0.05 for both groups) and postprandial (p < 0.001 for tacrolimus and p < 0.05 for cyclosporin) blood glucose concentrations. Fasting hyperinsulinaemia was observed in both transplant groups (p < 0.05) relative to the control subjects. Glucose-stimulated plasma immunoreactive insulin concentrations in the tacrolimus-treatment group were significantly higher than in the cyclosporin group (p < 0.05) and the controls (p < 0.001). Postprandial blood alanine concentrations were also significantly elevated in the tacrolimus group compared with both the controls (p < 0.001) and cyclosporin-treated patients (p < 0.001). The raised insulin concentrations with normal or increased blood glucose concentrations after renal transplantation suggests that insulin resistance was more marked in patients receiving tacrolimus-based immunosuppression.

Alanine↗
PubMed1999

A study of endothelial cell-lymphocyte responses in human renal transplantation.

Histological studies have demonstrated vascular damage in all types of allograft rejection. It is likely that donor endothelium suffers the major and the first insult by the recipient's immune system since, in vivo, capillary endothelium expresses human lymphocyte antigen (HLA) class I and class II antigens. The present study was designed to examine whether injury to donor endothelial cells (ECs) by recipient peripheral blood mononuclear cells (PBMCs) can be demonstrated in vitro, and whether there is a relationship between the in vitro findings and the clinical outcome of renal allografts. Twenty renal transplant recipients were included in this study, and all patients were followed up for 6 months. PBMCs were isolated from the renal transplant recipients on three occasions; in the first 24-h post-transplantation, at the beginning of the second week, and in the third week post-transplantation. Additional samples were taken at the time of any acute rejection episode. These patients received renal allografts from 15 local cadaveric donors whose ECs were isolated. Donor-specific ECs and the corresponding renal transplant recipients' PBMCs and sera were employed in proliferation and cytotoxicity assays. Our results show that donor-specific ECs consistently induced a highly significant degree of recipient lymphocyte proliferative response (p < 0.05). However, no significant correlation between acute graft rejection and the degree of donor-specific EC-induced recipient lymphocyte proliferation was found. In contrast, there was a significant correlation between lymphocyte-induced EC cytolytic effects and acute renal graft rejection (p < 0.05). When conducted in larger studies, such information can have important implications in clinical transplantation.

Coculture Techniques↗
PubMed1996

Parathyroidectomy in the west Midlands.

A retrospective audit was made of 101 patients undergoing parathyroidectomy, performed by 20 general surgeons in the West Midlands region during 1992. The mean number of cases per surgeon was five; nine surgeons performed fewer than three parathyroidectomies. Some 57 patients had primary hyperparathyroidism. Only seven were diagnosed by general practitioners and referral was invariably to a non-endocrine physician. Delay between diagnosis and surgical referral exceeded 2 years in 12 patients. Four patients (7 per cent) with primary hyperparathyroidism remained hypercalcaemic after first exploration; all were operated on by surgeons who performed fewer than four parathyroidectomies per year. Minor complications occurred in 32 per cent of patients. All 44 patients with renal hyperparathyroidism were treated in specialist units where diagnosis and treatment were expeditious; parathyroidectomy was successful in 41. Hyperparathyroidism should be managed in specialized units and by surgeons who perform parathyroidectomy frequently. A heightened awareness of primary hyperparathyroidism is required at primary care level.

Aged↗
PubMed1996

Lack of in vitro interaction between heparin and nitroglycerin.

Nitroglycerin has been reported to reduce activated partial thromboplastin time (aPTT) values in patients treated with concurrent heparin and nitroglycerin. However, in vivo studies have yielded conflicting results. In this in vitro evaluation, nitroglycerin was added to samples of pooled plasma from normal volunteers in concentrations of 0, 1, 10, 50, 100, 150, and 200 ng/mL. Preservative-free heparin was then added to the samples to produce final concentrations of 0, 0.3, and 0.6 U/mL. Activated partial thromboplastin time (aPTT) was determined for each sample using a single reagent. There were no significant differences in aPTT values among increasing nitroglycerin concentrations for any of the three levels of heparinization. No direct effect of nitroglycerin on the anticoagulant effect of heparin was observed, as measured by aPTT.

Blood Coagulation↗
PubMed1995

Anti-epithelial (anti-A549) antibodies: their nature, specificity and relevance to transplantation.

Several studies have addressed the possible importance of anti-epithelial cell antibodies in kidney transplantation using the A549 cell line as an in vitro model. In this paper we report our results using for the first time an enzyme-linked immunosorbent assay (ELISA) to detect the anti-A549 cell antibodies. Sera from 129 kidney transplant patients were tested for IgM anti-epithelial cell antibodies directed against the A549 cell line prior to transplantation; only three sera were positive (2.3%). 101 of these patients were then followed-up post-transplantation; sera were collected routinely at 2, 6 and 12 weeks and at the time of rejection episodes. All samples were also tested for cytomegalovirus (CMV) IgM antibodies. Sixteen patients developed anti-A549 IgM antibodies, and there was no correlation with acute graft rejection. Anti-epithelial antibodies showed no binding to sections of normal kidney or biopsies of rejected kidneys. Eleven patients were positive for anti-CMV IgM antibodies. In nine cases both IgM anti-A549 and IgM anti-CMV antibodies were found, which was a highly significant association (p < 0.001). Analysis of A549 cellular proteins by immunoblotting gave evidence for the presence of CMV polypeptides in the cell lysate. Electron-microscopic examination of A549 cell preparations revealed intracellular particles which were compatible in size with CMV. Polymerase chain reaction analysis confirmed the presence of a specific CMV DNA sequence in A549 cells of several batches from different sources. Our data strongly suggest that the A549 cell line used in several published reports is infected with CMV and that in the majority of cases the anti-A549 'anti-epithelial' antibodies found in renal transplant patients are anti-CMV antibodies.

Adolescent↗
PubMed1995

Measurement of proliferation in renal biopsy specimens: evidence of subclinical tubular damage in the nephrotic syndrome.

BACKGROUND: Proliferating cells can be detected in histological material in various ways. This investigation was to study the feasibility and usefulness of application of proliferation markers to routine renal biopsy specimens. METHODS: One hundred and thirteen renal biopsies fixed in formalin and embedded in paraffin were studied immunohistologically using antibody MIB 1, which recognises the Ki-67 antigen. Twenty-two biopsies were also immunostained with antibody PC10 against proliferating cell nuclear antigen. RESULTS: PC10 stained nuclei in all biopsies, including those that were negative with MIB 1. MIB 1 stained nuclei in endocapillary sites to various extents, and there was an average of less than one stained endocapillary nucleus per glomerulus in biopsies with IgA nephropathy and IgM nephropathy, conventionally regarded as types of proliferative glomerulonephritis. Glomerular extracapillary nuclei were stained by MIB 1 in vasculitic disorders and at the site of tip changes. MIB 1 also stained nuclei in the arterial intima, especially in vascular rejection, and in interstitial tissues, correlating with renal excretory function. Tubular nuclei stained by MIB 1 were common in biopsies from patients with renal impairment and in a group with the nephrotic syndrome, in many of whom renal function was normal. CONCLUSIONS: The main conclusions are that (1) immunohistological markers of proliferation can be applied to routine renal biopsy material; (2) PC10 appears to overestimate proliferation compared with MIB 1; and (3) there is evidence of subclinical tubular damage in the nephrotic syndrome, shown by increased tubular proliferation without clinical renal impairment. This observation seems not to have been made previously.

Antibodies, Monoclonal↗
PubMed1993

Organ donation.

Explore the source record for details and available documents.

Cadaver↗
PubMed1992

Clinical evaluation of a rapid parathyroid hormone assay.

Modifications to the incubation conditions of radioimmunoradiometric assay for whole molecule parathyroid hormone (PTH) permit accurate quantification of the hormone in the peripheral circulation within 1 h of sampling. We assessed the assay intraoperatively in 75 patients undergoing parathyroidectomy. Serum PTH concentration declined to less than 20% of its pre-operative value within 20 min of the successful completion of surgery provided that renal function was normal. In patients with chronic renal failure the rate of decline in serum PTH concentration after parathyroidectomy was slower in some cases. In four cases of unsuccessful parathyroidectomy, serum PTH concentration remained above 60% of its preoperative value. Intraoperative monitoring during parathyroidectomy using this rapid PTH assay offers considerable advantages to the surgeon over frozen section.

Adult↗
PubMed1990

Modification to a commercial immunoradiometric assay permitting intraoperative monitoring of parathyroid hormone levels.

We describe a modification to a commercially available immunoradiometric assay which reduces the turnaround time for parathyroid hormone (PTH) measurement to 1 h and permits intraoperative monitoring during parathyroidectomy. Alterations in PTH concentrations following removal of parathyroid tissue are compared with those of calcium, ionised calcium and phosphate. PTH measurements obtained intraoperatively permit definitive conclusions about the success of the operation within 1 h of sampling, allowing re-exploitation of the gland to take place immediately if necessary.

Calcium↗
PubMed1989

Selective conversion from azathioprine to cyclosporin for steroid-resistant rejection in renal transplants: an alternative therapy.

In 153 consecutive renal allograft recipients whose initial immunosuppression was prednisolone and azathioprine, 41 developed acute rejection episodes that were not reversed by 5-9 g of intravenous methylprednisolone. Renal histology showed cellular rejection in ten patients, vascular rejection in 12, and mixed cellular and vascular rejection in 16. Thirty-one patients were converted to cyclosporin in the first month post-transplant and ten in the second month. At the time of conversion, 20 patients were dialysis dependent and in the remainder the mean serum creatinine was 353 mumol/l (range 139-548 mumol/l). Renal function improved in 31 patients after conversion. Ten patients lost their grafts, of whom seven were on dialysis. There were no deaths and the 1-year graft survival was 75%. These data suggest that conversion from azathioprine to cyclosporin because of steroid-resistant rejection is an effective and safe strategy in patients whose initial immunosuppression is prednisolone and azathioprine.

Adolescent↗