Search PubMed⌕ Search

Biomedical subjects

S Martin

Publications and source records attributed to S Martin.

At least 397 records · Page 22Linked to original sources
PubMed1994

A retrospective flow cytometric crossmatch study in transplant recipients with autoreactive lymphocytotoxic antibodies.

Our previous data shows renal transplant recipients with autoreactive lymphocytotoxic antibodies to have a reduced transplant survival when compared to patients without autoantibodies. This could have been due to the presence of weak IgG antibodies inhibited by the dithiothreitol used to remove IgM antibodies in the pretransplant cytotoxicity crossmatch. That possibility was investigated in a retrospective study of 52 recipients of 57 renal transplants who were recrossmatched using a more sensitive flow cytometry crossmatch (FCXM) to detect recipient IgG antibodies to donor T and/or B cell splenic lymphocytes. Fourteen of the 57 (24%) transplants failed. Six losses were within the 1st month posttransplant and four of these were immunological failures. None of the transplant failures had a positive pretransplant FCXM. These results showed that the recipients with autoantibodies did not have pretransplant IgG anti-donor antibodies. The transplant failures did not, therefore, relate to the presence of antibodies undetected by the dithiothreitol-treated cytotoxicity crossmatch.

B-Lymphocytes↗
PubMed1994

Increased mortality due to cardiovascular disease in type 1 diabetic patients transplanted for end-stage renal failure.

The graft and patient survivals following renal transplantation in all Type 1 diabetic patients transplanted within the North-West of England between 1981 and 1990 at Manchester Royal Infirmary were studied. Fifty-two Type 1 (insulin-dependent) diabetic patients with end-stage renal failure due to diabetic nephropathy were transplanted during this period. They were compared to controls matched for age, sex, and year of transplantation and also to all 904 patients transplanted during the same period. Graft survival rates at 1 and 5 years in the diabetic patients were lower (80.8% and 62.1%, respectively), compared to controls (88.9% and 77.9%, respectively, p = 0.02) but were similar to those seen in all grafts (80.4% and 59.0%, respectively, p = NS). Actuarial patient survival rate at 5 years was lower in diabetic patients (76.3%) compared to the control group (94.2%, p = 0.003). Myocardial infarction was the main cause (60%) of death in diabetic patients. The results of this large recent series indicate that good graft and patient survival rates can be obtained in Type 1 diabetic patients, although they remain poorer than those of patients with non-diabetic renal disease. More rigorous pretransplantation cardiac assessment and treatment before acceptance of Type 1 diabetic patients for renal transplantation may help to improve patient survival.

Adult↗
PubMed1994

Prevention of perineal trauma by perineal massage during pregnancy: a pilot study.

Although the performance of perineal massage by a woman or her partner during the last weeks of pregnancy may help to prevent perineal trauma at delivery, the technique has never been evaluated rigorously. This study examined the feasibility of a randomized, controlled trial, and more specifically assessed the participation rate, the acceptability of the intervention, and whether or not an attending physician could remain blind to participants' groups. The pilot study was a single-blinded, randomized, controlled trial. Nulliparous women, 32 to 34 weeks pregnant, were recruited from June 8 to July 31, 1992, at the offices of family physicians and obstetricians who practice at the Hôpital du Saint-Sacrement in Quebec City. Women assigned to the intervention group practiced daily 10-minute perineal massage and completed a diary, and those in the control group had standard care. Women and attending physicians completed a questionnaire about the aspect of blindness. Among the 174 women who delivered during the study period, 104 (59.8%) were approached by a midwife and 46 (26.4%) were randomized. Twenty (91.0%) of the 22 women in the massage group returned their perineal massage diaries. Based on the postpartum questionnaire, 20 women practiced the technique at least four times a week for three weeks or longer. No woman in the control group practiced massage. The attending physician was aware of the woman's group in only three instances (6.7%). Based on the results of this pilot study, a randomized, controlled trial to evaluate the efficacy of perineal massage in preventing perineal trauma at birth appears feasible.

Adult↗
PubMed1994

T cell recognition of haptens, a molecular view.

Our review attempts to summarize the present knowledge on how T lymphocytes recognize chemically modified autologous cells. Concerning the broad spectrum of chemically and drug-induced allergic and autoimmune diseases, the molecular mechanisms of hapten recognition by T cells are clearly of more than academic interest. The past few years revealed that in contrast to the expectations of many researchers, major histocompatibility complex (MHC)-restricted hapten-specific T cell receptors in their majority do not react to covalently modified MHC molecules, but to haptenized peptides associated with the MHC peptide-binding groove. This finding allowed the introduction of synthetic hapten-peptide conjugates, the MHC specificity of which may be predetermined by allele-specific peptide sequence motifs. Thus, it has now become feasible to selectively hapten-modify defined sets of MHC molecules on living cells, and to study their immunological properties. In that way two major types of hapten-specific T cell receptors were identified: one reacting to hapten without caring for the chemical composition of the carrier peptide, and the other contacting hapten and peptide by two apparently independent contact sites. The consequences of these findings for hapten-specific allergies and autoimmunities, but also for our molecular understanding of antigen recognition by T cells are discussed.

Amino Acid Sequence↗
PubMed1994

Serial analysis of circulating adhesion molecules and TNF receptor in serum from patients with multiple sclerosis: cICAM-1 is an indicator for relapse.

We determined the serum levels for circulating adhesion molecules (circulating intercellular adhesion molecule-1 [cICAM-1], circulating endothelial leukocyte adhesion molecule-1 [cELAM-1], and circulating L-selectin [cL-selectin]) and circulating tumor necrosis factor receptor (cTNF-R) p60 in 29 patients with relapsing-remitting MS serially over a period of 12 months. During this period there were 27 relapses in 14 patients (48%). There was progression of disease activity in 12/25 patients (48%), as assessed by the occurrence of new lesions on nonenhancing, T2-weighted MRIs of the head. Clinically active patients with relapse or disease progression on MRI (n = 18) had frequent fluctuations in their serum levels for cICAM-1 if compared to patients with stable MS (n = 11). There were significant differences in the cumulative cICAM-1 production between the two groups (502 +/- 218 ng/ml in active versus 225 +/- 82 ng/ml in stable MS patients; p < 0.001). cTNF-R p60 serum levels were higher in patients with stable compared to active disease (2.3 +/- 0.5 ng/ml versus 1.5 +/- 0.6 ng/ml; p < 0.005). A significant increase in cICAM-1 levels was present at the time of a relapse (799 +/- 263 ng/ml versus 449 +/- 95 ng/ml; p < 0.001), whereas the highest serum levels for cTNF-R p60 occurred 4 weeks after the onset of a relapse (1.8 +/- 0.5 ng/ml at relapse versus 2.3 +/- 0.6 ng/ml 4 weeks after a relapse; p < 0.01). Interestingly, the cL-selectin serum levels in all MS patients were significantly higher than in healthy donors, whereas there were no differences for cELAM-1. These results reflect distinct changes of inflammatory variables in serum of patients with MS and revealed that cICAM-1 is an indicator for disease activity and that high serum levels for cTNF-R p60 are associated with remission.

Adult↗
PubMed1994

Minimal cross-sectional areas, nasal peak flow and patients' satisfaction in septoplasty and inferior turbinectomy.

Changes in minimal cross-sectional areas, measured by acoustic rhinometry as well as nasal peak flow fractions and linear analogue patients' satisfaction scores, were measured in two groups of eight patients each, undergoing septoplasty alone and septoplasty combined with trimming of the inferior turbinates, respectively. Patients who had both procedures performed showed the greatest increase in both minimal cross-sectional areas and peak flow fractions, and both of these parameters were closely correlated with patients' satisfaction, whether the patient was satisfied or not. Pre-operative nasal obstruction was worse in the dual-procedure group, but post-operative satisfaction was significantly greater in these patients. Both acoustic rhinometry and nasal peak flow fractions can be recommended as accurate and easy to perform pre-operative measurements in patients undergoing surgery for nasal obstruction.

Adolescent↗
PubMed1994

Synergistic effects of tumour necrosis factor and morphine on gut barrier function.

OBJECTIVE: To study the effects of tumour necrosis factor (TNF) and morphine on intestinal permeability, intestinal transit and bacterial translocation in the rat. DESIGN: A randomized interventional controlled experiment. SETTING: University surgery and microbiology research laboratory. PARTICIPANTS: Forty-four rats in five groups as follows: control (n = 9); treated with morphine every 2 hours for 8 hours (n = 9); treated with TNF for 5 minutes (n = 10); treated with TNF plus morphine every 2 hours for 8 hours (n = 6); and treated with TNF plus morphine every 3 hours for 24 hours (n = 10). MAIN OUTCOME MEASURES: Intestinal permeability as measured by the uptake of chromium-51 ethylenediaminetetraacetate (51Cr-EDTA) over 8 hours, intestinal transit as measured by the amount of 51Cr-EDTA remaining in the gastrointestinal tract at the time of animal sacrifice, intestinal bacteria counts and translocation of bacteria as measured from bacterial counts of mesenteric lymph nodes, spleen and liver at the time of sacrifice. RESULTS: Morphine increased intestinal transit time and ileal bacteria counts (p < 0.05). TNF alone did not increase intestinal permeability or bacterial translocation. TNF plus morphine increased intestinal transit time, intestinal permeability, bacterial counts and bacterial translocation (p < 0.05). CONCLUSIONS: Morphine or increased intestinal transit time, or both, increases the concentration of intestinal bacteria. Morphine plus TNF increases intestinal bacteria counts, intestinal permeability and bacterial translocation. Morphine alone does not increase intestinal permeability or bacterial translocation.

Analysis of Variance↗
PubMed1994

Abnormal TNF-alpha production in diabetes-prone BB rats: enhanced TNF-alpha expression and defective PGE2 feedback inhibition.

Upon stimulation with lipopolysaccharide (LPS), peritoneal macrophages from diabetes-prone Bio-Breeding (BB) rats secrete more tumour necrosis factor-alpha (TNF-alpha) than macrophages from diabetes-resistant BB or normal Wistar rats. Enhanced transcription was demonstrated by Northern blot analysis and at the single cell level by mRNA: RNA hybridization. Cytofluorometry analysis showed 2-4 times more plasma membrane and total cell-associated TNF-alpha in macrophages of diabetes-prone BB rats. The analysis of fluorescence intensity showed a single peak, and TNF-alpha mRNA was found in > 90% of macrophages. These findings exclude TNF hypersecretion as being due to an abnormal subfraction of cells. TNF-alpha gene hyperexpression in diabetes-prone BB rats was not due to mutations in the regulatory regions of the promoter, which could be shown by cloning and sequencing of the TNF-alpha promoter in the three rat strains. When searching for other regulatory defects we found the production of prostaglandin E2 (PGE2) in response to LPS to be up to 10 times lower in macrophages from diabetes-prone BB rats than from Wistar rats. Furthermore, BB rats macrophages required significantly higher concentrations of PGE2 for suppression of TNF-alpha secretion. We conclude that abnormal TNF-alpha production in macrophages from diabetes-prone BB rats is due to enhanced gene transcription and translation and that this is associated with defective PGE2 feedback inhibition.

Animals↗
PubMed1993

Titin folding energy and elasticity.

Molecules of the giant protein titin are responsible for the passive elasticity and central A-band location of muscle myofibrils. The molecular mechanism of titin elasticity is not known, but the I-band region of the molecule appears capable of approximately fourfold reversible extension. Such large extensions are likely to involve unfolding of titin domains. In the present experiments, equilibrium unfolding of titin from rabbit skeletal muscles was studied in vitro by fluorescence and circular dichroism spectroscopy, after addition of guanidinium chloride. The data suggest two unfolding transitions, both of which appear cooperative. The second transition is likely to involve complete unfolding of the immunoglobulin- and fibronectin-like domains from which the molecules is composed. The free energy associated with this transition is comparable with the energy required to extend titin molecules to the maximum amount seen in situ.

Animals↗
PubMed1993

Transcription and translation of inducible nitric oxide synthase in the pancreas of prediabetic BB rats.

The inducible NO synthase (iNOS) was found to be expressed in pancreatic lesions of adult diabetes-prone BB rats. Pancreatic iNOS mRNA was detected by reverse transcriptase PCR in pancreatic RNA of adult diabetes-prone BB rats but not in normal Wistar rats, young diabetes-prone BB rats without insulitis or in diabetes-resistant BB rats. Immunohistochemistry of pancreatic sections using an iNOS-specific antiserum labeled the pancreas of adult diabetes-prone BB rats but not Wistar rats. Parallel staining for ED1-positive macrophages showed restriction of iNOS expression to areas of islet infiltration by macrophages. In conclusion, the data provide direct evidence for enhanced expression of inducible NO synthase in tissue lesions during the development of autoimmune diabetes.

Amino Acid Oxidoreductases↗