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Biomedical subjects

A Ting

Publications and source records attributed to A Ting.

At least 73 records · Page 4Linked to original sources
PubMed1988

Stress fractures of the tarsal navicular in long-distance runners.

The authors report on a study that attempted to (1) determine anatomic variations that predispose runners to tarsal navicular stress fractures; (2) study that loading responses of runners with stress fractures and of uninjured runners; (3) study the mechanical factors and biomechanics of the foot during running; (4) define a population at risk for developing stress fractures; and (5) propose an alteration in footwear that may reduce the force across the talonavicular joint.

Adolescent↗
PubMed1987

Cyclosporin conversion versus conventional immunosuppression: long-term follow-up and histological evaluation.

129 patients who received a cadaver renal transplant entered a randomised prospective trial of cyclosporin for 3 months with conversion to azathioprine and prednisolone compared with conventional therapy of azathioprine and prednisolone. In the 64 patients who received cyclosporin, actuarial patient survival was 92%, and actuarial graft survival was 72% and 67% at 1 and 4 years after transplantation. Graft survival was significantly better (p less than 0.03) than in the 65 patients who received conventional therapy, in whom actuarial patient survival was 94%, and actuarial graft survival was 59% and 47% at 1 and 4 years. Renal function and other side-effects improved quickly after conversion with the better renal function maintained throughout follow-up. Renal biopsies at 90 days and 1 year in all patients did not show consistent improvement after conversion from cyclosporin in the histological features that might be attributable to cyclosporin toxicity. After conversion, 32% of the patients had acute rejection, generally within 30 days. 1 graft was lost to early acute rejection after conversion and another was lost 3 months later from acute-on-chronic rejection. A total of 8 grafts were lost to chronic rejection in the cyclosporin-treated group and 6 in the conventional group. The improvement in renal function obtained with this protocol of short-term cyclosporin with conversion to azathioprine and prednisolone has to be balanced against the risk of acute rejection and even loss of the graft after conversion.

Administration, Oral↗
PubMed1987

Release of arachidonic acid metabolites by human monocytes or lymphocytes: effect of treatment with interferon on stimulation by phorbol ester or calcium ionophore.

The simultaneous production of prostaglandins, leukotrienes, and hydroxyeicosatetraenoic acids was studied in human peripheral blood monocytes obtained by counter-current centrifugal elutriation. Monocytes prelabeled for 4 hr with [3H]arachidonic acid (AA) released label into the surrounding medium in response to treatment with 12-O-tetradecanoylphorbol-13-acetate (TPA) or calcium ionophore (A23187). High-performance liquid chromatography of monocyte supernatants demonstrated that labeled compounds included those which eluted with authentic standards for thromboxane B2, 12-L-hydroxy-5,8,10-heptadecatrienoic acid (HHT), 6-keto-prostaglandin F alpha, prostaglandin E2, and 15-hydroxyeicosatetraenoic acid (HETE). 5-HETE and leukotriene B4 (LtB4) were detected only in response to ionophore treatment. Highly purified lymphocytes did not convert AA to autocoids, despite the release of free arachidonate in response to either stimulus. Pretreatment of monocytes with recombinant human interferon (IFN)-gamma or IFN-alpha for 18 hr resulted in enhanced release of labeled arachidonic acid and increased conversion to autocoids after TPA or ionophore stimulation. Absolute amounts of prostaglandin E2 produced in response to TPA or ionophore treatment were increased as well. These results demonstrate the autocoid profile released by stimulated human monocytes and illustrate the effects of IFN treatment on the production of lipoxygenase metabolites of arachidonic acid as well as cyclooxygenase products.

Arachidonic Acid↗
PubMed1987

A positive B cell crossmatch due to IgG anti-HLA-DQ antibody present at the time of transplantation in a successful renal allograft.

The role of a positive B cell crossmatch in renal transplantation is uncertain, partly because of the difficulty in determining the true specificity of the various antibodies that may cause a positive crossmatch. We have used monoclonal antibodies against HLA class I, HLA-DR and HLA-DQ antigens to inhibit cytotoxicity of sera from renal patients, in order to define the specificity of a positive B cell crossmatch. We have used reduction with dithiothreitol (DTT) to identify the immunoglobulin class. These methods were used to identify the specificity and immunoglobulin class of the antibody causing a positive B cell crossmatch in a highly sensitised patient. The results show that the antibody was IgG anti HLA-DQ and the graft was functioning 1 year after transplantation. Immunoperoxidase techniques demonstrated a normal expression of HLA-DQ antigen in biopsies of the transplanted kidney. The successful outcome of the transplant raises questions about the role of anti-HLA class II antibodies in renal transplantation.

B-Lymphocytes↗
PubMed1986

Lysolecithin-induced Ca2+ uptake by pigeon red cells.

Lysolecithin (LPC) induced a rapid but transitory increase in 45Ca2+ influx, and an abrupt 45Ca2+ net uptake by pigeon red cells. The effect on uptake was seen with doses of added lysolecithin calculated to be 2.1-8.4% of the cytoplasmic membrane phospholipid, well within the reported physiological range of 1-9%. Lysolecithin effects were not due to prelytic membrane changes nor action as a platelet activating factor agonist. Changes in the amino acids in the medium mimicking human homocysteinuria, an atherosclerosis risk factor, increased the lysolecithin effect. The findings are consistent with a role for lysolecithin in atherosclerosis.

Amino Acid Metabolism, Inborn Errors↗
PubMed1986

Diabetic retinopathy and its association with limited joint mobility.

Limited joint mobility (LJM) of the small joints of the hands was studied in 63 adult insulin-dependent diabetics to determine whether LJM might serve as an indicator to the presence of diabetic retinopathy in diabetics of long duration. In 123 non-diabetic controls, and in the 63 diabetics, the prevalence of LJM increased with age. In the diabetics, LJM was not associated with retinopathy, long-term glycaemic control or HLA type. The hypothesis that LJM is useful as a predictor of the development of retinopathy in young diabetics does not extend to older diabetics of long duration. LJM and retinopathy may have a different pathophysiology.

Adult↗
PubMed1986

Failure of platelet transfusion to improve human renal allograft survival.

Platelets, expressing only class I antigens on their surface, have been shown to improve renal allograft survival in some experimental models but do not lead to humoral sensitization. In this pilot study, 24 previously untransfused patients were given 3 platelet transfusions at 2-week intervals before renal transplantation. Twelve patients (group 1) received 200 X 10(8) platelets contaminated by 15 X 10(6) leukocytes in each transfusion, and 42% developed cytotoxic antibodies; 12 further patients (group 2) received a purified preparation containing 200 X 10(8) platelets and less than 5 X 10(6) leukocytes, and no cytotoxic antibodies were detected. Using a more sensitive flow cytometry technique, 83% of group 1 but only 17% of group 2 (P less than 0.004) responded to their platelet donors. From each group 9 patients have been transplanted. Four grafts in group 1 and 6 in group 2 have failed, yielding a 1-year graft survival rate of 44%, compared with 69% in blood-transfused patients (P = 0.03). Pure platelet transfusions, using our protocol, do not appear to improve renal allograft survival, and minimal contamination by leukocytes can lead to humoral sensitization.

Blood Transfusion↗
PubMed1986

Immunoglobulin class and specificity of antibodies causing positive T cell crossmatches. Relationship to renal transplant outcome.

A group of 42 renal transplants performed in the presence of a T-cell-positive crossmatch were analyzed to determine the class and specificity of the donor-reactive cytotoxic antibodies. Dithiothreitol (DTT) was used to reduce IgM antibodies and a monoclonal antibody directed at a monomorphic determinant present on all HLA class I antigens (PA2.6) was used to inhibit cytotoxicity of anti-HLA class I antibodies. Sera from 26 of the positive crossmatches were considered to be autoreactive, and the positive crossmatch proved to be due to IgM and not directed at HLA class I in each case. One year graft survival was 100% in the 5 living-related and 60% in the 21 cadaver donor transplants, of which 10 were regrafts. Of the 42 positive crossmatches, 16 were not due to autoantibody. One was positive in the current serum taken at the time of transplantation, and this graft was rejected hyperacutely, while 15 were positive with peak but not current serum samples. Of the positive crossmatches, 12 were inhibited by PA2.6 demonstrating that they were directed at HLA class I antigens. PA2.6 inhibition could not be shown in 3 and in 1 DTT reduction was technically unsatisfactory. While 4 of the 7 positive crossmatches due to IgM antibodies were successful, the 7 transplants performed with positive crossmatches due to IgG antibodies all failed. DTT reduction and inhibition of cytotoxicity by PA2.6 helps to define positive crossmatches with donor T cells that are not associated with graft failure. Transplantation in the presence of a peak positive T cell crossmatch due to an anti-HLA antibody might only be successful if the antibody in the peak serum is of the IgM class.

Antibodies, Monoclonal↗