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Biomedical subjects

J M Martin

Publications and source records attributed to J M Martin.

At least 73 records · Page 4Linked to original sources
PubMed1994

Modulation of IGF mRNA abundance during stretch-induced skeletal muscle hypertrophy and regression.

Increased load on a muscle (synergistic overload or stretch) results in muscle hypertrophy. The expression of insulin-like growth factor I (IGF-I) mRNA in rat skeletal muscle is increased during synergistic overload-induced hypertrophy. Although it has also been established that fasting animals lose muscle protein, it has been shown that compensatory muscle hypertrophy occurs in adult fasting rats that are undergoing a net loss of body weight. The purpose of this investigation was to determine whether a relationship exists between IGF-I mRNA levels and muscle growth and regression. This was accomplished by examining whether IGF-I mRNA levels were altered during muscle hypertrophy after stretch and regression and the effect of fasting on IGF-I mRNA levels during stretch-induced hypertrophy. Patagialis (PAT) muscle weights increased 13 and 44% at 2 and 11 days of stretch, respectively. However, after removal of the stretch stimulus on day 11, PAT weights began to decrease, reaching control weights by 18 days. During the first time point (2 days), PAT muscle IGF-I mRNA remained constant. IGF-I mRNA abundance was threefold greater than contralateral control levels by 11 days of stretch. IGF-I mRNA levels decreased but remained significantly above control levels throughout the regression of hypertrophy (13, 18, and 25 days). Fasting did not alter PAT muscle response to stretch. After 11 days of stretch, PAT muscle weight increased 60% compared with contralateral control muscles and IGF-I mRNA levels increased three-fold. This study supports a role for IGF-I in muscle hypertrophy but not muscle atrophy.

Animals↗
PubMed1994

Effect of somatotropin on myosin expression in pigs.

Daily administration of recombinant porcine somatotropin (rpST) has marked effects on growth performance of swine. Protein accretion rates are dramatically increased with rpST treatment. However, the effect of rpST on specific muscle proteins has not been addressed. The purpose of this study was to examine the effects of rpST on 1) the distribution pattern of isomyosins, 2) the total myosin heavy chain protein levels, and 3) myosin heavy chain mRNA abundance present in swine skeletal muscle. There were no differences in myosin isoform composition in the longissimus muscle resulting from porcine somatotropin treatment. There were also no differences in the myosin heavy chain protein concentration within the longissimus muscles. In accordance with the protein levels, myosin heavy chain mRNA expression was not altered with rpST treatment. This study shows that although the pig responds to rpST with increased protein accretion rates, the proportion of myosin per milligram of total protein remains constant. Myosin was not altered by type, concentration, or expression level. By combining these tools we are now able to examine a myosin on both a protein and message level throughout growth.

Animals↗
PubMed1993

A software for the description of workplaces.

Three softwares have been designed, the first for job histories, the second for job-exposure matrices, and this, the third and latest, for workplace descriptions. The first two softwares were presented in earlier articles while the current article presents the software for workplace descriptions. Workplace description has been based on the idea that a job is best described by listing its constituent tasks so as to determine associated risks better. The three softwares, the job history software (JHS), the job-exposure software (JES) and the workplace description software (WDS) are interfaced and constitute an integrated professional risk surveillance (PRS) system.

Algorithms↗
PubMed1993

Isolation and characterization of a novel cDNA which identifies both neural-specific and ubiquitously expressed GS alpha mRNAs.

Heterotrimeric G proteins consisting of alpha, beta, and gamma subunits couple sensory, hormone, and neurotransmitter receptors to intracellular and transmembrane effectors. Several splicing variants of the GS (the G protein that stimulates adenylyl cyclase) alpha subunit (GS alpha) have been described. Some of these couple receptors to stimulation of adenylyl cyclase and Ca2+ channels, whereas others encode truncated proteins whose functions are not currently defined. We describe a 1321N1 human astrocytoma cDNA clone for a novel GS alpha isoform isolated from astrocytoma cells (G(astro)) that is identical to GS alpha-1 with the exception of a novel 5' sequence extending into the previously described exon 1 of GS alpha, a single base change, and an alternative polyadenylation site. Analysis by northern blotting and reverse transcription/PCR confirms the presence of an mRNA corresponding to this cDNA in astrocytoma cells. Additional northern analysis indicates that G(astro) recognizes two novel GS alpha mRNAs in the rat: a 2.0-kb mRNA expressed only in neural and neuroendocrine tissues and a 1.8-kb mRNA that is ubiquitously expressed. Functional analysis of G(astro) is complicated by the apparent insertion of alphoid satellite DNA into the transcription unit. The resulting cDNA encodes a truncated protein that may be translated from the methionine in exon 2 as previously described.

Amino Acid Sequence↗
PubMed1993

Latent membrane protein of Epstein-Barr virus induces cellular phenotypes independently of expression of Bcl-2.

The stable expression of the Epstein-Barr virus (EBV) latent membrane protein (LMP) in certain EBV-negative Burkitt's lymphoma cell lines correlates with an increased expression of the oncogene Bcl-2 (S. Henderson, M. Rowe, C. Gregory, D. Croom-Carter, F. Wang, R. Longnecker, E. Kieff, and A. Rickinson, Cell 65:1107-1115, 1991). This finding is consistent with a model in which Bcl-2 contributes to the immortalization of B cells mediated by EBV. We therefore asked whether the expression of Bcl-2 protein correlates with the induction of three cellular phenotypes induced by or associated with LMP. The expression of Bcl-2 in primary B cells infected with the B95-8 strain of EBV varied between 1 and 1.8 times that in uninfected cells when 50% of the cells were infected, expressed LMP, and incorporated 20-fold more [3H]thymidine than did uninfected cells. This finding indicates that induced proliferation of these primary cells is not sufficient to induce Bcl-2. We found that BALB/c 3T3 cells and their derivatives transformed by LMP do not express Bcl-2 detectably. The expression of LMP at high levels in lymphoid cells is cytotoxic and correlates with an increased expression of Bcl-2 following stable selection for the introduced LMP gene; 2 days after transfection, control vector- and LMP-transfected populations, however, express equal levels of Bcl-2 protein. We also analyzed transient expression of LMP in an EBV-negative Burkitt's lymphoma cell line. Infection of BJAB cells with the B95-8 strain of EBV results in an increase in Bcl-2 expression with a time course similar to that of LMP expression, and LMP alone transiently induces an increase in Bcl-2 expression in these cells. We interpret these observations to indicate that increased expression of Bcl-2 is unlikely to contribute to the ability of EBV to immortalize primary B cells and that both the transformation of rodent cells and the cytotoxicity mediated by LMP are independent of Bcl-2.

3T3 Cells↗
PubMed1993

Identification of a genomic fragment of Mycobacterium tuberculosis responsible for in vivo growth advantage.

The purpose of this work was to develop a system to identify virulence determinants of M. tuberculosis by genetic complementation. The ability to grow in mouse spleen and/or lung was defined as a potential phenotype for virulence. Enrichment for growing recombinant clones from a pool of H37Ra transformants containing the integrating pYUB178::H37Rv cosmid library was accomplished by in vivo selection. A molecular strategy was devised to isolate and clone the 25-kb H37Rv genomic fragment ivg that conferred in vivo growth advantage to H37Ra. This study is a first step toward understanding the genetics of virulence in M. tuberculosis. A detailed description of these experiments has been submitted for publication in Infection and Immunity.

Animals↗
PubMed1992

A bovine albumin peptide as a possible trigger of insulin-dependent diabetes mellitus.

BACKGROUND: Cow's milk has been implicated as a possible trigger of the autoimmune response that destroys pancreatic beta cells in genetically susceptible hosts, thus causing diabetes mellitus. Studies in animals have suggested that bovine serum albumin (BSA) is the milk protein responsible, and an albumin peptide containing 17 amino acids (ABBOS) may be the reactive epitope. Antibodies to this peptide react with p69, a beta-cell surface protein that may represent the target antigen for milk-induced beta-cell--specific immunity. METHODS: We used immunoassays and Western blot analysis to analyze anti-BSA antibodies in the serum of 142 children with insulin-dependent diabetes mellitus, 79 healthy children, and 300 adult blood donors. Anti-ABBOS antibodies were measured in 44 diabetic patients at the time of diagnosis, three to four months later, and one to two years later. RESULTS: All the diabetic patients had elevated serum concentrations of IgG anti-BSA antibodies (but not of antibodies to other milk proteins), the bulk of which were specific for ABBOS: The mean (+/- SE) concentration was 8.5 +/- 0.2 kilofluorescence units (kfU) per microliter, as compared with 1.3 +/- 0.1 kfU per microliter in the healthy children. IgA antibodies were elevated as well, but not IgM antibodies. The antibody concentrations declined after diagnosis, reaching normal levels in most patients within one to two years. The initial decline involved anti-ABBOS--specific antibodies almost exclusively. Much lower serum concentrations of anti-BSA antibodies were found in all 379 control subjects, but only 2.5 percent of them had small amounts of ABBOS-specific IgG. CONCLUSIONS: Patients with insulin-dependent diabetes mellitus have immunity to cow's-milk albumin, with antibodies to an albumin peptide that are capable of reacting with a beta-cell--specific surface protein. Such antibodies could participate in the development of islet dysfunction.

Antibodies↗
PubMed1992

Free radical activity during development of insulin-dependent diabetes mellitus in the rat.

Free radical-induced lipid peroxidation was quantified by measuring expired pentane from diabetic prone BB Wistar rats of 45-90 d of age. Insulin-dependent diabetes mellitus was manifest at the age of 71 +/- 8 d. Expired pentane increased from 2.1 +/- 0.7 to 5.0 +/- 3.0 pmol/100g/min (p less than 0.01) at manifestation of the disease and remained high throughout the test period. In healthy age-matched control rats it persisted low. In rats made diabetic with streptozotocin, expired pentane remained low. The changes in expired pentane suggest that the development of endogenous insulin-dependent diabetes mellitus in BB rats is associated with increased free radical activity. This is not due to hyperglycemia or ketosis per se, and reflects a fundamental difference in the free radical activity between the spontaneously diabetic BB rats and the disease produced by streptozotocin. Development of spontaneous insulin-dependent diabetes in BB rats is associated with increased free radical activity that persists after the manifestation of the disease.

Animals↗
PubMed1992

Localization of calcium changes in stimulated rat mast cells.

We studied intracellular free, bound, and sequestered calcium in rat mast cells after various stimulations. The use of a fluorescent probe combined with digitized imaging on individual living cells demonstrated transient increases of free Ca2+ in the micromolar range. The use of histochemical techniques (K pyroantimonate and anhydrous fixation), together with X-ray microanalysis, energy electron-loss spectroscopy, and electron spectroscopic imaging, revealed large amounts of stored calcium within the cells (in the millimolar range). Chelation experiments and stimulations enabled us to identify at least two pools of bound calcium which exhibited different dynamic behaviors. Stimulation in the presence of EGTA did not modify calcium from granules, granule membranes, and heterochromatin, whereas it decreased calcium from other cell compartments. Stimulation triggered variations in the amount of bound calcium but they did not parallel free calcium movements. Hence, whereas free calcium is implicated in exocytosis, bound calcium may be involved in altogether different cell functions.

Animals↗
PubMed1992

Invasive hemodynamic monitoring in pregnancy.

When the pregnant woman develops an acute or critical illness requiring invasive hemodynamic monitoring, it is imperative to consider physiologic changes that occur during pregnancy that impact on assessment parameters. Awareness of both the alterations in these parameters and the changes in arterial blood gas values guide nursing care that continues to support perfusion and oxygenation needs unique to pregnancy. When critical care capabilities are not available in the labor and delivery unit, the obstetric patient is most often transferred to a medical or surgical intensive care unit. In such cases, consultation with obstetric staff is warranted.

Critical Care↗
PubMed1992

Principles in hemodynamic assessment.

Use of invasive hemodynamic monitoring provides more thorough assessment of hemodynamic function and may reveal abnormal data before the development of adverse clinical signs and symptoms. The obstetric nurse caring for critically ill patients is responsible for understanding the principles associated with hemodynamic monitoring and interpretation of data to better plan and implement nursing care.

Critical Care↗
PubMed1992

Renal dialysis in pregnancy.

Dialysis may be needed, either acutely or on a chronic basis, during pregnancy for a variety of reasons. Advances in erythropoietin, transplant, and hormonal therapies may increase the chances of pregnancy in women with chronic renal failure. Providing care to this population of patients is a challenge to nephrology and obstetric nurses. It is important for the obstetric nurse to understand the fundamental principles of dialysis to collaborate in the planning and implementation of care for these patients.

Critical Care↗
PubMed1992

Evaluation of immune complexes after immunotherapy with wheat flour in bakers' asthma.

Inhalant food allergy has been described many times in literature, but double-blind clinical trials to support successful hyposensitization to these allergens has seldom been reported. Some authors have suspected that certain adverse reactions after immunotherapy may be mediated by immune complexes. Furthermore, the FDA does not recommend injection therapy with food extracts. We present a study on the detection of adverse effects after immunotherapy with an inhalant food (wheat flour) in a double-blind clinical trial in 26 patients with bakers' asthma. We investigated the presence of circulating immune complexes (CICs) after 2 years of treatment with hyposensitization to wheat flour.

Antigen-Antibody Complex↗