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Biomedical subjects

A Martin

Publications and source records attributed to A Martin.

At least 613 records · Page 34Linked to original sources
PubMed1989

The effect of calcitriol on natural killer cell activity in hemodialyzed patients.

We report the effect of calcitriol on natural killer (NK) cell activity in patients with chronic renal failure undergoing long-term hemodialysis. Natural killer cytotoxicity was significantly decreased in these patients when compared to healthy control subjects (13.1 +/- 1.3 vs 38.8 +/- 2.4%, P less than 0.001). These patients also have decreased levels of calcitriol (17 +/- 3 vs 36 +/- 3 pg/ml, P less than 0.001). After 14 days of oral treatment with calcitriol at a dose of 0.5 micrograms per day, a significant increase in NK activity was observed (20.2 +/- 1.6%, P less than 0.001). This increase was maintained after 28 days of treatment (21.1 +/- 2%, P less than 0.001). These results suggest that the decreased serum calcitriol might contribute to the diminished NK activity found in hemodialyzed patients, and suggests a new potential therapeutical utility of calcitriol as modulator of the immune function in these patients.

Adult↗
PubMed1989

Immunolocalisation and imaging of small cell cancer xenografts by the IgG2a monoclonal antibody SWA11.

We describe here a murine monoclonal antibody of the IgG2a isotype which was generated against the SW2 human small cell carcinoma cell line. The antibody, SWA11, was shown to bind to a partially defined antigen preferentially expressed on cell lines of small cell carcinoma origin. In vitro binding studies revealed 6.1 x 10(5) antigenic sites on the SW2 cell line and the Ka to be 1.2 x 10(9)M-1. Following injection into mice bearing 1-2 cm3 SW2 xenografts, SWA11 showed strong selective accumulation in the small cell heterotransplants with a tumour to blood ratio of 7.5:1 at day 4. Other tumour to organ ratios were similarly high at 19:1, 22:1 and 12:1 for liver, kidney and spleen respectively. The absolute amount of SWA11 which localised was 10.5% of total injected material per gram tumour at day 2 and this level did not markedly decrease by day 4. The high ability of SWA11 to localise to SCC xenografts was confirmed by external gamma scintigraphy. The potential application of SWA11 as a model system for in vivo radioimmunotherapy is discussed.

Animals↗
PubMed1989

Antibody responses to sheep erythrocytes for White Leghorn chickens differing in haplotypes of the major histocompatibility complex (B).

Lines of White Leghorn chickens were developed by selection for high (HA) or low (LA) antibody response to sheep red blood cells (SRBC) and then backcrossed to provide individuals segregating for haplotypes B13 and B21 of the major histocompatibility complex (MHC) within each selected line. Although antibody response to SRBC was consistently higher in background genome HA than LA, there was a significant interaction between background genome and MHC haplotypes. The interaction resulted from higher antibody response in B13/B21 individuals of line HA and in B21/B21 individuals of line LA. Thus, response to SRBC was dependent on particular haplotype combinations present at the MHC as well as the background genome in which they were expressed.

Animals↗
PubMed1989

Marek's disease and major histocompatibility complex haplotypes in chickens selected for high or low antibody response.

Sublines of chickens differing in genotypes at the major histocompatibility complex (MHC) were developed from lines selected for high (HA) and low (LA) antibody response to sheep erythrocytes. To evaluate the influence of MHC genotypes in diverse background genomes on resistance to Marek's disease, chicks with MHC genotypes B13B13, B13B21 and B21B21 from both background genomes were exposed naturally commencing at 1 day of age. Individuals which died up to 120 days of age were autopsied to determine cause of death. Mortality due to Marek's disease was greater for HA than LA chickens and greater for males than females. Interactions of MHC genotypes with background genome and with sex suggest a complex picture of the influence of MHC genotypes. A heterozygous advantage for resistance to Marek's disease was noted, as would be predicted by genetic theory concerning maintenance of polymorphism at the MHC.

Animals↗
PubMed1989

Antiviral activity of a D-glucosamine derivative against herpetic ulcers (HSV type 2) in rabbit cornea.

Although most herpetic ocular infections in adults are caused by herpesvirus hominis type 1, several cases of culture proved HSV-2 ocular infection in adults have been described, with more severe and prolonged disease. In a screening for new antiherpetic compounds, we investigated the efficacy in vivo of a new compound, nitroderivative of D-glucosaminhydrochloride (GN-11) in comparison with D-glucosaminhydrochloride (GN), Acyclovir (ACV) and placebo against herpetic keratitis of herpes simplex type 2 in 4 x 4 eyes from 4 x 4 rabbits, respectively. ACV and GN-11 showed similar results. The treatment with GN-11 retarded the appearance of herpetic lesions, which were small and diffuse in comparison with the placebo group. A total recovery was obtained on the 12th day of the treatment. In the ACV treated group, a minimal number of small lesions appeared, but the eyes recovered normality on the 7th day of treatment. The appearance of acute herpetic keratitis was prevented by GN-11. Placebo and GN treated groups showed similar evolution, with lost vision and neurological involvement on the 7th day of infection.

Acyclovir↗
PubMed1989

Successful production of intrathyroidal human T cell hybridomas: evidence for intact helper T cell function in Graves' disease.

We have developed a series of human intrathyroidal T-T cell hybridomas and evaluated their phenotypic characteristics and lymphokine secretions in order to further understand the role of the T cell in Graves' disease. Mitogen-stimulated T cell blasts were generated from intrathyroidal lymphocyte preparations and fused with a hypoxanthine-, aminopterin-, and thymidine-sensitive variant of the Molt 4 human leukemia T cell line. The resulting intrathyroidal T-T cell hybridomas and T-T cell hybridomas obtained from normal peripheral blood mitogen-stimulated T cell blasts were expanded and tested for their biological function. None of the generated T cell hybridomas exhibited antigen-specific IL-2 secretion when stimulated with autologous thyrocytes, although 60% of the hybridomas expressed CD3 antigen and the T cell receptor alpha/beta heterodimer. However, 9 intrathyroidal and 11 peripheral blood T cell hybridomas secreted a factor(s) that significantly enhanced immunoglobulin G secretion in vitro (P less than 0.005, by Student-Newman-Keuls test; mean +/- SEM, 338 +/- 60% increase). In summary, we have successfully used a technique that allows the construction of T-T cell hybridomas derived from intrathyroidal T cell cultures. The data demonstrated that a predominance of helper factor-secreting T cells were available for fusion within the Graves' thyroid gland. Such observations are further evidence for intact T cell help within the thyroid gland of patients with Graves' disease.

Adenoma↗
PubMed1989

Neuronal typology of Gallotia galloti optic tectum.

The object of this work has been to show neuronal typology and stratification of the optic tectum in Gallotia galloti adult specimens so as to have a basic model for the neuronal genesis study. As methodology Nissl and Golgi-Stensaas technique were employed. Six strata have been identified that include 14 layers where the neuronal types can be included, poligonals, bipolar, monopolar and stellate types. The stratification of the optic tectum in the 14 layers is corroborated in Reptiles, a fact which is maintained in birds, and is reduced in amphibians, urodels, and fish here the reptil optic tectum presentes an extraordinary importance in the study of the auditive and visual vias in phylogeny.

Animals↗
PubMed1989

Colonoscopy in Jamaica--a 12-year experience.

Four hundred and nine colonoscopic examinations were performed in 335 patients over a 12-year period in Jamaica. The main indications were suspected polyps (34%) rectal bleeding (22%) and suspected carcinoma (11%). Total colonoscopy was performed in 33% of cases. The ascending colon and hepatic flexure were examined in a further 25%, and the transverse colon in another 21%. Endoscopic examination of the suspected abnormal area was possible in all cases. In 142 examinations, no abnormality was detected, reflecting a false positive Barium enema in some. Polyps were found in 135 examinations, diverticula in 69 and carcinoma in 13. There were no complications. Colonoscopy was more sensitive and specific than Barium enema. The Barium enema findings were incorrect in 91 of 224 examinations (41%). Colonoscopy is a safe and accurate procedure which enables improved patient management.

Adolescent↗
PubMed1989

The predictive value of serum enzymes for perioperative myocardial infarction after cardiac operations. An autopsy study.

We evaluated the utility of serum enzyme and isoenzyme activities for detecting autopsy-proved perioperative myocardial infarction in patients who died after cardiac operations. We studied 79 patients who had autopsies performed after coronary artery bypass grafting or valve replacement, or both. Thirty-seven had histologic evidence of a perioperative myocardial infarction. We found statistically significant differences between the group of patients with infarction and the group without infarction when we compared the mean activities of creatine kinase, creatine kinase MB, aspartate aminotransferase, and the lactate dehydrogenase-1/lactate dehydrogenase-2 ratio. The postoperative changes in serum enzymes were analyzed by logistic regression for their relation to perioperative myocardial infarction. Creatine kinase MB exhibited the best diagnostic association with the presence of perioperative myocardial infarction. The lactate dehydrogenase-1/lactate dehydrogenase-2 ratio correlated to a lesser extent with infarction. Adjustment of the diagnostic cutoff to 133 U/L for creatine kinase-MB measured 15 hours after operation yielded a sensitivity of 0.60 and a specificity of 1.0. This study demonstrates that no combination of enzyme activity changes after operation can completely discriminate all patients with perioperative myocardial infarction from those without. Nonetheless, measurement of creatine kinase MB activity provide 96% accuracy for diagnosing infarction at a prevalence of 10%.

Aspartate Aminotransferases↗
PubMed1988

Infrared spectroscopic studies of Acholeplasma laidlawaii B membranes. Comparison of the gel to liquid-crystal phase transition in intact cells and isolated membranes.

The physical state of the membrane lipids in the plasma membranes of intact, live Acholeplasma laidlawii B cells was probed by Fourier-transform infrared spectroscopy and compared with that in isolated membranes. Infrared spectra of live A. laidlawii B cells, enriched biosynthetically in the presence of avidin, with saturated deuterated and unsaturated non-deuterated fatty acids have been recorded at a variety of temperatures. The results indicate that within the temperature range of the gel to liquid-crystal phase transition, the live cells are able to keep the 'fluidity' of their plasma membranes at a considerably higher value compared to that in the isolated membranes at the same temperature. While this is a generally valid observation, the degree by which live and isolated membranes differ in their liquid-crystal-phase content at a given temperature depends on the nature of the exogenous fatty acid and the temperature of growth.

Acholeplasma↗