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Biomedical subjects

R Minter

Publications and source records attributed to R Minter.

10 recordsLinked to original sources
PubMed2000

Xenopus NK cells identified by novel monoclonal antibodies.

Early-thymectomized (Tx) Xenopus frogs, which are permanently deficient in T cells, are used as a model sytem for the characterization of novel monoclonal antibodies (mAb) which identify candidate NK cells at the amphibian level of evolution. Hybridomas, generated from mice immunized with splenocytes from Tx Xenopus following B cell and thrombocyte depletion, were screened by flow cytometry. Three mAb (1F8, 4D4 and 1G5) were identified that stained increased proportions of splenocytes from Tx compared with control frogs. These mAb identified lymphoid populations from Xenopus spleen, liver and gut which, after 48 h culture in growth factor-rich medium, exhibited spontanous killing of MHC-deficient allotumor targets. mAb-defined splenocytes also rapidly induced apoptosis of such tumor targets. Dual color analysis confirmed that NK cells are neither T nor B cells. Cytospins of splenocytes isolated with anti-NK mAb revealed large lymphoid cells with distinct pseudopodia. Immunohistology indicated each anti-NK mAb routinely labeled cells within the gut epithelium but NK cells were difficult to visualize in spleen sections. Western blotting of spleen, liver and intestinal lysates subjected to sodium dodecyl sulfate polyacrylamide gel electrophoresis showed that 1G5 reacted strongly with protein bands of approximately 70 - 85 kDa, whereas mAb 1F8 and 4D4 stained less intensely, but identified similar protein bands.

Animals↗
PubMed2000

Molecular cloning of the gene for interleukin-1beta from Xenopus laevis and analysis of expression in vivo and in vitro.

The Xenopus cDNA for interleukin-1beta (IL-1B) was cloned and sequenced. The gene contains 1,462 nucleotides that translate in a single reading frame to give a predicted 283-amino acid IL-1beta molecule. The translated molecule contains a single potential glycosylation site, a readily identifiable IL-1 family signature, and has highest homology to chicken IL-1beta by phylogenetic tree analysis and sequence similarity. It lacks a signal peptide in common with other known IL-1B genes, and lacks a clear ICE (caspase) cut site in common with other nonmammalian IL-1B genes sequenced to date. RT-PCR was used to study sites of IL-1B transcript expression, 24 h following injection of lipopolysaccharide (LPS). Expression was detected in the brain, liver, kidney, and spleen, with expression weakest in the brain and strongest in the spleen. No transcript expression was detectable following injection of saline. Northern blot analysis was used to quantify the induction of IL-1B expression in splenocytes following in vivo or in vitro stimulation with LPS. The results are discussed in relation to the potential role of IL-1beta in amphibian immune responses.

Amino Acid Sequence↗
PubMed2000

LPS-induced liver injury in D-galactosamine-sensitized mice requires secreted TNF-alpha and the TNF-p55 receptor.

Lipopolysaccharide and D-galactosamine induced lethality and apoptotic liver injury is dependent on endogenously produced tumor necrosis factor (TNF)-alpha. The present study was undertaken to determine whether membrane-associated or secreted TNF-alpha signaling through the p55 or p75 receptor was responsible for survival and hepatic injury after lipopolysaccharide administration in D-galactosamine-sensitized mice. Transgenic mice expressing null forms of TNF-alpha, the p55 and p75 receptor, and mice expressing only a cell-associated form of TNF-alpha were challenged with 8 mg D-galactosamine and 100 ng lipopolysaccharide. Mortality and apoptotic liver injury were only seen in wild-type and p75 knockout mice. p75 Knockout mice had significantly higher concentrations of plasma TNF-alpha than any other experimental group (P </= 0.05) and tended to have the highest mortality and liver injury. In contrast, p55 and TNF-alpha knockout mice and animals expressing only a cell-associated form of TNF-alpha exhibited no mortality or liver injury. We conclude that survival and apoptotic liver injury in response to lipopolysaccharide and D-galactosamine are dependent exclusively on secreted TNF-alpha signaling through the p55 receptor.

Alanine Transaminase↗
PubMed1999

Androgen receptor polymorphisms: association with prostate cancer risk, relapse and overall survival.

Several reports have suggested that one or both of the trinucleotide repeat polymorphisms in the human androgen receptor (hAR) gene, (CAG)n coding for polyglutamine and (GGC)n coding for polyglycine, may be associated with prostate cancer risk; but no study has investigated their association with disease progression. We present here a study of both hAR trinucleotide repeat polymorphisms not only as they relate to the initial diagnosis but also as they are associated with disease progression after therapy. Lymphocyte DNA samples from 178 British Caucasian prostate cancer patients and 195 control individuals were genotyped by PCR for the (CAG)n and (GGC)n polymorphisms in hAR. Univariate Cox proportional hazard analysis indicated that stage, grade and GGC repeat length were individually significant factors associated with disease-free survival (DFS) and overall survival (OS). The relative risk (RR) of relapse for men with more than 16 GGC repeats was 1.74 (95% CI 1. 08-2.79) and of dying from any cause, 1.98 (1.13-3.45). Adjusting for stage and grade, GGC effects remained but were not significant (RR(DFS)= 1.60, p = 0.052; RR(OS)= 1.65, p = 0.088). The greatest effects were in stage T1-T2 (RR(DFS)= 3.56, 95% CI 1.13-11.21) and grade 1 (RR(DFS)= 6.47, 95% CI 0.57-72.8) tumours. No differences between patient and control allele distributions were found by odds-ratio analysis, nor were trends with stage or grade evident in the proportion of short CAG alleles. Non-significant trends with stage and grade were found in the proportion of short GGC alleles. The (GGC)n polymorphism in this population is a significant predictor of disease outcome. Since the (GGC)(n) effect is strongest in early-stage tumours, this marker may help forecast aggressive behaviour and could be used to identify those patients meriting more radical treatment.

Aged↗
PubMed1998

Stereotactic core biopsy reduces the reexcision rate and the cost of mammographically detected cancer.

The management of patients with mammographic abnormalities is rapidly shifting from needle-localized surgical biopsy (NLB) to stereotactic core biopsy (SCB). The precise role of SCB in the management of nonpalpable breast cancer remains to be defined. The purpose of this study was to compare SCB to NLB in the diagnosis of mammographically detected breast cancer in women who underwent breast-conserving surgery. The records of all patients with nonpalpable breast cancer who underwent breast-conserving surgery from 1/1/95 to 6/1/97 were analyzed with respect to method of diagnosis, time interval from detection to diagnosis and breast-conserving surgery, volume of breast tissue excised, margin status and reexcision rate, number of surgical procedures, and total charges and costs per patient. During a 30-month period, 117 patients with nonpalpable breast cancer underwent breast-conserving surgery. The diagnosis was made by NLB in 69 patients and SCB in 48 patients. The time from detection to diagnosis and breast-conserving surgery was 1.7 +/- 0.5 and 8.1 +/- 1.2 days for SCB patients and 6. 8 +/- 1.3 and 16.9 +/- 2.3 days for NLB patients (P < 0.01). The volume of breast tissue removed was 117.9 +/- 5.6 cm3 for SCB patients versus 75.2 +/- 2.9 cm3 for NLB patients (P < 0.01). Three SCB patients (6%) had positive margins, while 38 NLB patients (55%) had positive margins (P < 0.01). Only 1 SCB patient (2%) was reexcised, while 34 NLB patients (50%) were reexcised (P < 0.01). Eighty-nine percent of SCB patients had a single surgical procedure compared to 39% of NLB patients (P < 0.001). Patients who underwent SCB had reduced total charges and total costs per patient compared to NLB patients ($11,700 +/- $554 and $3537 +/- $167 per SCB patient versus $15,654 +/- $706 and $4853 +/- $198 per NLB patient, P < 0. 0001). Stereotactic core biopsy shortens the time from detection at mammography to diagnosis and breast-conserving therapy, permits appropriate discussion of treatment alternatives, reduces the positive margin rate and reexcision rate, and may represent a significant cost savings in the management of nonpalpable breast cancer.

Biopsy, Needle↗
PubMed1998

T-cell and natural killer cell development in thymectomized Xenopus.

The Xenopus early-thymectomy model system is used to investigate the extent to which the thymus controls T-cell development and to probe the evolution of natural killer (NK) cells. Loss of T-cell function following thymectomy, together with the paucity of cells expressing monoclonal antibody-defined T-cell surface markers, and greatly reduced expression of T-cell receptor beta transcripts in spleen, liver and intestine, indicate that T-cell development in minimal in the absence of the thymus. Our findings therefore mitigate against the idea that a substantial extrathymic pathway of T-cell development exists in early vertebrate evolution. Rather, they suggest that in this amphibian representative T cells are predominately thymus dependent. In vitro studies with control and thymectomized Xenopus splenocytes reveal that a non-T/non-B population and also two T-cell subsets all display natural cytotoxicity towards allogeneic thymus lymphoid tumour cells (which are deficient in MHC antigen expression). Since Xenopus thymectomized early in larval development are permanently deficient in T cells, they may provide a useful phylogenetic model for the study of NK cells.

Animals↗
PubMed1998

Internet course on total quality management.

The Internet provides new opportunities to information-based industries such as universities. If a vast majority of potential customers of our programs have access to the Internet, then it is conceivable that many universities will begin teaching Internet courses and that such courses could, in many cases, replace or at least augment existing face-to-face classroom activities. This paper is an account of one such course at Cleveland State University and the type of policy issues raised by the course at this institution.

Adult↗
PubMed1990

Formation of the 37-kD protein-acetaldehyde adduct in primary cultured rat hepatocytes exposed to alcohol.

We have previously reported that a 37-kD liver protein formed an adduct with acetaldehyde in vivo when rats were fed alcohol chronically. To understand the mechanism of the formation of this protein-acetaldehyde adduct, rat hepatocytes in primary culture were treated with ethanol in vitro for several days. When cultured in hormone-enriched and trace metal-enriched Waymouth's medium, alcohol dehydrogenase activities in hepatocytes decreased only about 30% during 6 days of culture. At the end of the specified time, protein extracts of hepatocytes were immunotransblotted with rabbit immunoglobulin G that recognized acetaldehyde adduct as an epitope. The 37-kD protein-acetaldehyde adduct band could be detected within 3 days in cells that had been treated with alcohol at a steady-state concentration as low as 5 mmol/L. Although the maximal intensity was obtained at approximately 10 to 40 mmol/L ethanol, addition of cyanamide (an inhibitor of aldehyde dehydrogenase) further increased the intensity of this protein-acetaldehyde adduct band by more than twofold. A good correlation existed between acetaldehyde concentration in the medium and the intensity of the 37-kD protein-acetaldehyde adduct band. Formation of the 37-kD liver protein-acetaldehyde adduct is thus dependent on acetaldehyde, and the 37-kD protein is apparently unusually susceptible to chemical modification by acetaldehyde.

Acetaldehyde↗