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Biomedical subjects

R E Martin

Publications and source records attributed to R E Martin.

At least 73 records · Page 4Linked to original sources
PubMed1986

Ascaris suum: regulation of myosin light chain phosphorylation from adult skeletal muscle.

The regulatory myosin light chain in Ascaris suum muscle was isolated in a phospho and dephosphoform. In freshly dissected tissue or in control muscle segments perfused with saline, approximately 48% of the total myosin light chain pool was phosphorylated. Perfusion with acetylcholine caused a dose dependent increase in muscle contraction but no change in myosin light chain phosphorylation. In contrast, perfusion with gamma-aminobutyric acid resulted in a dose dependent relaxation of A. suum muscle and a decrease in myosin light chain phosphorylation so that only 18% of the total myosin light chain remained phosphorylated. Trifluoroperizine, an inhibitor of myosin light chain phosphorylation, did not inhibit acetylcholine induced muscle contraction. Collectively, the data support the hypothesis that A. suum muscle contraction is mediated by actin.

Acetylcholine↗
PubMed1986

Elusive diagnosis of tuberculous peritonitis.

Four patients with tuberculous peritonitis were diagnosed at our hospital in one year. In two patients it was only after surgery for iatrogenic bowel perforation that the diagnosis was made. The difficulty in recognizing this illness in those patients prompted a review of cases in Arkansas over the past nine years. A total of 27 cases have been documented; in 14 the diagnosis was made after considerable delay or during surgery for another diagnosis. Tuberculous peritonitis should be considered in any patient with ascites and chronic abdominal pain.

Adolescent↗
PubMed1986

Effect of nutritional status, age at weaning and room temperature on growth and systemic immune response of weanling pigs.

Two experiments were conducted to determine the effect of nutritional status, age at weaning and room temperature on growth and immune response of pigs. In the first experiment, 72 pigs were weaned at either 2 or 3 wk and fed either a complex, simple-adequate or simple-inadequate diet for a 24-d period. Total antibody (TAb) titers in response to injections of human red blood cells (RBC) on either 0, 4, or 16 d postweaning were not affected by age at weaning or dietary treatments even though the nutritional status was compromised to such an extent that pigs fed the simple-adequate diet gained at one-half the rate (.172 vs .349 kg/d) of pigs fed the complex or simple-adequate diets (P less than .01). In Exp. 2, the immunological response of 144 pigs weaned at 3 wk were evaluated at 4 and 8 d postweaning. Pigs were weaned into rooms that averaged either 25 or 18 C, and were fed either a complex or simplex-adequate diet at either ad libitum (AL) or restricted (Res) levels for a 24-d period. Restriction of either the complex or simple diet for the first 16 d of the trial drastically reduced (P less than .01) the growth rates of Res pigs compared with AL pigs (.042 vs .236 kg/d). There were no differences in skinfold thickness (Sf) or TAb, 2-mercaptoethanol sensitive (MEs) and resistant (MEr) antibody titers when pigs were inoculated with phytohemagglutinin-P (PHA-P) or RBC at 4 d postweaning regardless of room temperature, diet source or feeding level.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1984

Cell cycle analysis of facial mesenchyme in the chick embryo. II. Label dilution studies and developmental fate of slow cycling cells.

The spatial distribution and developmental fate of quiescent and/or slow cycling cell populations of the primary palate were studied employing label-dilution techniques. 3 1/2-day-old chick embryos were labelled sequentially for 12 h with [3H]thymidine and then chased with cold thymidine. The embryos were reincubated to continue development and were subsequently sacrificed at intervals from the end of labelling at 4 days to 14 days of incubation (10 days after labelling) and processed for autoradiography. Retention of label was used as the assay for identification of quiescent and/or slow-cycling cells. Grain density over the nuclei of labelled cells was determined in the maxillary process and the roof of the stomodeum. Cells with a label density at later time points comparable to that found in cells immediately after the labelling period were defined as label-retaining cells, i.e. those which had become quiescent or had significantly altered generation times. The location and developmental fate of these cell populations were confirmed using slides containing adjacent sections stained with Nuclear Fast Red, Alcian Blue, and Tartrazine. The results demonstrated an association between label-retaining cells and chondrogenic differentiation in the roof of the stomodeum. Subpopulations of label-retaining cells (quiescent and/or slow cycling) which we believe to be prechondroblasts appeared in the chondrogenic region of the roof of the stomodeum prior to, or coincident with, cartilage formation. The retention of label, as evidenced by comparison of nuclear grain counts at the end of the labelling period with subsequent time points, indicated that a cell cycle block may have occurred in the prechondroblastic cell population. The block lasted until these cells expressed the chondrogenic phenotype, after which they resumed cell division.

Animals↗
PubMed1983

Glucose-6-phosphatase: is activity regulated by phosphorylation-dephosphorylation?

Incubation of rat liver microsomes with ATP and Mg2+ in the absence or presence of an exogenous protein kinase showed no changes in the activity of glucose-6-phosphatase (D-glucose-6-phosphate phosphohydrolase, EC 3.1.3.9). These observations confirm the recent findings of the Burchells and colleagues and refute on methodological grounds the earlier conclusions of Begley and Craft implicating regulation of this enzyme by protein phosphorylation-dephosphorylation. In other studies, the time-dependent inactivation of microsomal glucose-6-phosphatase by incubation with deoxycholate was used to obtain the inactive enzyme which in the presence of a protein kinase, ATP, and Mg2+ could not be restored to its original level. A number of substrates and competitive inhibitors of glucose-6-phosphatase, most notably vanadate which is the most potent inhibitor of the enzyme identified, stabilized this enzyme against its time-dependent inactivation in the presence of detergent as effectively as did fluoride and molybdate which are also effective competitive inhibitors of glucose-6-phosphatase. An alternative explanation to the involvement of a phosphoprotein phosphatase, as discussed by the Burchells, in the time-dependent inactivation of glucose-6-phosphatase is thus suggested.

Adenosine Triphosphate↗
PubMed1979

Isocaloric exchange of dietary starch and sucrose in humans. I. Effects on levels of fasting blood lipids.

For 6 weeks, 10 men and nine women aged 35 to 55 consumed each of two diets in a cross-over design. The diets were comprised of identical natural foods with 30% of the calories as either sucrose or cooked wheat starch. Carbohydrate, fat and protein supplied 43, 42, and 15% of the calories, respectively. Of the calories 10% were eaten at breakfast (7:00 to 8:30 AM) and 90% at dinner (4:30 to 6:30 PM). Initial body weights were essentially maintained. Total serum lipids, triglycerides, and total cholesterol levels were significantly higher when the subjects consumed the sucrose diet than when they consumed the starch diet. Increases associated with the sucrose diet were greatest for triglycerides (33.0%). In a subgroup of nine subjects with triglyceride levels above the normal range, sucrose feeding increased triglyceride levels 45.2%. Triglycerides and pre-beta lipoproteins were significantly higher in males than in females. Pre-beta lipoproteins were 32% higher when the subjects consumed sucrose than when they consumed starch. For alpha and beta lipoproteins, small, nonsignificant increases were associated with sucrose feeding. Serum free fatty acids were not affected by diet. These results indicate that the consumption of sucrose can increase blood lipids that are considered to be risk factors in heart disease and that males and carbohydrate-sensitive individuals may be more susceptible than others to the effects of sucrose.

Adult↗
PubMed1978

Case report: computed tomography of cystadenoma of the pancreas.

Cystadenoma is an unusual pancreatic tumor characterized by large-sized polycystic components. It is located totally within the pancreas and may cause retroperitoneal collateral venous return. These characteristics can be easily visualized by computed tomography, thus making it a very effective modality in the differential diagnosis of pancreatic lesions.

Aged↗
PubMed1975

Iatrogenic lesions of the colon and rectum.

Our ability to document a number of examples of iatrogenic lesions of the colon and rectum in three general hospitals confirms the multiplicity of these lesions as presented in the literature. It appears that the careful surgeon and his associates would well heed the old admonition known as Murphy's law, that "Anything that can go wrong will go wrong." In the daily practice of the general surgeon and proctologist, it is apparent that gentleness in approaching any anal-rectal examination for either diagnostic or therapeutic purposes is mandatory. The insertion of any foreign object, be it an examining finger, a thermometer, enema tip, or proctoscope, may subject the patient to an inadvertent injury of significant proportion. The dangers inherent in the evaluation and treatment of patients with recognized disease processes is significantly greater than that associated with routine and screening examinations. Morbidity and mortality have been shown to be associated with the barium enema as well as with the barium enema as well as with some of the newer radiologic procedures such as mesenteric angiography. The use of tap water for enemas has produced morbidity both from thermal injuries and from electrolyte depletion. Antibiotics and chemotherapeutic drugs frequently result in colon and rectal disease, and therapeutic procedures directed at organs adjacent to the colon and rectum have resulted in a number of iatrogenic lesions. This reviews confirms reports of others that iatrogenic lesions of the colon and rectum are not solely due to the physician's inexperience, as significant numbers of these lesions were the result of the diagnostic or therapeutic efforts of men of considerable experience and skill. Advanced age of the patient and diseases leading to changes in the character of the bowel wall frequently were factors in the production of these lesions. A poorly prepared bowel has led to increased morbidity and mortality associated with iatrogenic perforations. The early recognition of these lesions and prompt medical and surgical management diminishes both the morbidity and mortality associated with such injuries.

Adult↗
PubMedDate not supplied

Docosahexaenoic, arachidonic, palmitic, and oleic acids are differentially esterified into phospholipids of frog retina.

Docosahexaenoic acid (22:6n-3) is highly enriched in the retina. To determine if retinal cells take up and metabolize fatty acids in a specific manner, retinas from Rana pipiens were incubated for 3 h with an equimolar mixture of tritiated 22:6n-3, arachidonic acid (20:4n-6), palmitic acid, and oleic acid. The radiolabeling of retinal lipids was determined and compared to the endogenous fatty acid content of the lipids. The results showed that in most, but not all, cases, the relative labeling with the four precursor fatty acids was similar to their relative abundance in each glycerolipid. Thus, during retinal glycerolipid synthesis, either through de novo or acyl exchange reactions, fatty acids are incorporated in proportions reflecting their steady-state mass levels. Since other studies with labeled glycerol have shown greater differences between early labeling patterns and molecular species mass, the final incorporation we report may be due primarily to acyl exchange reactions.

Animals↗
PubMedDate not supplied

The association between cryptococcal variety and immunocompetent and immunocompromised hosts.

The varieties of Cryptococcus neoformans serotypes are neoformans and gattii. Data suggest an association between cryptococcal variety and host immune status. In addition, the two varieties differ in their epidemiology and pathogenicity. Furthermore, symptoms, outcome, and response of cryptococcosis to antifungal therapy may vary. The two varieties also differ in immune-modulating effects. Sparse clinical data suggest var. gattii is more virulent and may be more recalcitrant to antifungal therapy. Also, its infections produce more sequelae. A better understanding of how cryptococcal variety influences the clinical course and response to the treatment of cryptococcosis is needed. Clinicians should be aware of the association, especially in patients with refractory disease. It may be useful to type the isolate to the variety level and administer prolonged antifungal therapy.

AIDS-Related Opportunistic Infections↗