Search PubMed⌕ Search

Biomedical subjects

M L Martin

Publications and source records attributed to M L Martin.

At least 73 records · Page 4Linked to original sources
PubMed1991

Transient heat shock in mid-G1-phase of the C6 glioma cell cycle impairs entry into S-phase.

Synchronous populations of rat C6 glioma cells have been obtained by a mitotic selection procedure and used to establish the effect of transient temperature elevation on their progression through the cell cycle. A transient 3-h exposure to a 42 degree C heat shock within defined area in the mid-G1-phase of the cell cycle has been demonstrated to impair progression to S-phase. This anti-proliferative heat shock effect was not apparent in asynchronous cell populations. A small, but significant, decrease in 3H-thymidine incorporation was observed (approximately 5%) following an 8-h exposure to heat shock.

Animals↗
PubMed1991

Participation of older adults in health programs and research: a critical review of the literature.

This collection of five papers evaluates the participation of older adults in clinical trials, health promotion/disease prevention initiatives, and health programs designed to maintain or improve the functioning of chronically ill older adults. Understanding the willingness or unwillingness of older adults to participate in these programs is critical to the development and implementation of health programs and policies for this population. In this introductory paper we briefly review illustrative literature to provide both an overview of the participation of older adults in health programs as well as background information relevant to the symposium papers.

Aged↗
PubMed1991

A collaborative model for the clinical education of baccalaureate nursing students.

Quality clinical supervision is fundamental for the consolidation of knowledge and the development of a professional identity for baccalaureate nursing students. Problems in providing high-quality clinical supervision range from a lack of practitioner role models to inadequate or unsupportive learning environments. Collaboration between the education and service sectors allows for the development of enriched clinical learning experiences for students. This paper describes an innovative collaborative educational process developed by McMaster University School of Nursing and the Nursing and Education Departments at Hamilton Psychiatric Hospital, Hamilton, Ontario, Canada. Front-line nursing staff are the clinical supervisors, with support from clinical nurse specialists, the hospital educator and the university faculty member. When compared to more traditional approaches, this model ensures that the students receive more variety in placements and access to expert human resources.

Education Department, Hospital↗
PubMed1991

Isolation of Escherichia coli serotype O157:H7 and other Shiga-like-toxin-producing E. coli from dairy cattle.

We examined 1,266 fecal specimens from healthy cattle during the investigations of two sporadic cases of hemolytic uremic syndrome associated with raw milk consumption and an outbreak of gastroenteritis and hemolytic uremic syndrome caused by Escherichia coli serotype O157:H7. We collected specimens from heifers, calves, and adult cows on 22 farms, in a stockyard, and in a packing house. We also collected 3 raw hamburger specimens from a restaurant and 23 raw milk samples from two farms. All specimens were examined for E. coli O157:H7 by using sorbitol-MacConkey agar, H immobilization, O157 agglutination, and tissue culture cytotoxicity. E. coli O157:H7 was isolated from 16 heifers or calves and 1 adult cow on 22 farms, 1 stockyard calf, 2 beef specimens, and 1 raw milk sample. Selected fecal specimens were also examined for the presence of other Shiga-like-toxin-producing E. coli (SLTEC) by testing polymyxin B extracts of colony sweeps and then testing individual colonies for toxin production. SLTEC other than O157 was isolated from 8 of 10 farms investigated and from the stockyard; 8% of adult cows and 19% of heifers and calves were positive for SLTEC. Several animals were positive for SLTEC by colony sweep only. This investigation demonstrates that dairy cattle are a reservoir of E. coli O157:H7 and other SLTEC.

Animals↗
PubMed1991

Effects of body fat distribution on regional lipolysis in obesity.

UNLABELLED: To determine the contribution of the major body fat depots to systemic free fatty acid (FFA) availability, palmitate ([1-14C]-palmitate) release was measured from leg (lower body) and non-leg (upper body) fat in eight upper body obese (UB Ob), six lower body obese (LB Ob), and six nonobese (Non Ob) age-matched premenopausal women in the overnight postabsorptive state. Splanchnic palmitate release was determined in 16 of these subjects. RESULTS: total palmitate release was greater in UB Ob (P less than 0.005) than LB Ob or Non Ob women (161 +/- 16 vs. 111 +/- 9 vs. 92 +/- 9 mumol/min, respectively). Despite increased leg fat mass in obese women, leg palmitate release was similar in each group. Therefore, leg fat palmitate release was greater in Non Ob women than LB Ob (P less than 0.01) or UB Ob (P = 0.06) women (3.7 +/- 0.3 vs. 2.4 +/- 0.2 vs. 2.7 +/- 0.2 mumol.kg fat-1.min-1, respectively). Upper body fat palmitate release was less (P less than 0.01) in LB Ob than Non Ob or UB Ob women (3.0 +/- 0.4 vs. 5.0 +/- 0.3 vs. 4.9 +/- 0.4 mumol.kg fat-1.min-1, respectively). Splanchnic palmitate release accounted for 20-32% of upper body fat palmitate release in each group (P = NS between groups). Leg fat palmitate release was significantly less than upper body fat palmitate release. We conclude that the major difference in resting FFA metabolism between UB Ob and LB Ob women is the ability of the later to down-regulate upper body fat lipolysis to maintain normal FFA availability.

Adipose Tissue↗
PubMed1991

Use of birth defects monitoring programs for assessing the effects of maternal substance abuse on pregnancy outcomes.

We have attempted to demonstrate that birth defects surveillance systems are a unique adjunct to clinical research data on maternal exposures, including substances of abuse. Surveillance system data reflect the experiences of the populations from which they are drawn and the characteristics of the people in those populations. Sensitive systems may reveal trends in health status and changes in behavioral, cultural, social, or environmental exposures. They can be used to monitor changing trends, to identify clusters for investigation, to generate and test hypotheses, and to conduct epidemiological studies. For researchers to interpret data derived from surveillance systems appropriately and wisely, they need a thorough knowledge of the data sources, the data-collection procedures, and the intent of the surveillance systems. Researchers using surveillance data should have a thorough understanding of the quality of their data and the methodologic subtleties that bear on its interpretation; researchers reviewing scientific literature based on surveillance data should be aware of the strengths and limitations inherent in the data.

Abnormalities, Drug-Induced↗
PubMed1990

Arrhythmias in patients with CHF. Should they be treated?

Ventricular arrhythmias are a major cause of death in patients with congestive heart failure. Dr Ellenbogen and his associates discuss the current thinking, based on recent studies, concerning use of antiarrhythmic agents to prevent sudden cardiac death in these patients. As they point out, the proper antiarrhythmic therapy may be crucial to long-term survival.

Adult↗
PubMed1990

2H-NMR resolution of the methylenic isotopomers of ethanol applied to the study of stereospecific enzyme-catalysed exchange.

We have shown that site-specific natural isotope fractionation of hydrogen studied by NMR (SNIF-NMR) is an important source of information on the mechanistic and environmental effects which govern the photosynthesis of sugars and their fermentation into ethanol. Three isotope ratios associated with the methyl, methylene, and hydroxyl sites of ethanol are determined in achiral media. In this study we show that complementary information about possible stereospecific mechanisms involving the methylenic hydrogens is also rendered accessible by 2H-NMR enantiomeric resolution. The synthesis of mandelate esters enables exchange between the pro-R site of ethanol and water to be investigated. Simultaneous access to the three site-specific isotope ratios of the ethyl group is obtained at isotopic dilutions close to the natural ones. Mediation of the exchange by the enzymic system alcohol dehydrogenase-alpha-lipoyldehydrogenase and by the yeast Saccharomyces cerevisiae are compared. The progress of the reaction can be followed quantitatively as a function of time and the occurrence of glycolytic metabolism of endogeneous materials by yeast can be substantiated in a one-pot experiment.

Alcohol Dehydrogenase↗
PubMed1990

Descriptive epidemiology of selected malformations of the aorta, Atlanta, 1970-1983.

To augment available population-based epidemiologic data for obstructive malformations of the aorta, we studied the descriptive epidemiology of coarctation, hypoplasia, and interruption of the aortic arch in Atlanta from 1970 through 1983. The study used data from the Metropolitan Atlanta Congenital Defects Program, a population-based birth defects registry. One hundred seventy infants were identified as having either interruption of the aortic arch (18), coarctation (131), or hypoplasia (21) of the aorta. The prevalence per 10,000 live births was as follows: interruption of the aortic arch, 0.50; coarctation, 3.62; and hypoplasia of the aorta, 0.58. Despite the differences in rates, the descriptive epidemiology for the three malformations was similar. None of the malformations was associated with gender or maternal age. Birth prevalence for whites was higher than that for other races; the increase, however, was statistically significant only for coarctation. Birth prevalence of these malformations increased during the period of observation, with the greatest increase (threefold) seen with interruption of the aortic arch. The rates for all malformation groups also showed a strong inverse association with birthweight.

Adult↗
PubMed1990

In vitro screening for anticonvulsant-induced teratogenesis in neural primary cultures and cell lines.

To establish inherent potential for the induction of neural tube defects the ability of selected anticonvulsant agents to interfere with cell division has been established in vitro using an antiproliferative assay in clonal cell lines and a cytotoxicity assay using primary cultures of cerebral cortex neurons at different stages of development. In order to evaluate the relative toxicities of these agents their in vitro effects were determined at 2-3 times the plasma therapeutic level. By these procedures valproate and the benzodiazepines, diazepam and clonazepam, exerted a potent antiproliferative action which could not be attributed to increased cytotoxicity. In contrast phenytoin was markedly cytotoxic but was without an antiproliferative action. This cytotoxicity was most pronounced during the periods of extensive fibre outgrowth. When compared to epidemiological and animal study data, agents which inhibited cell proliferation within twice therapeutic concentration were consistently associated with major neural tube malformations. However phenytoin, found to be positive in the cell cytotoxicity assay, is not associated with neural tube malformations but rather is primarily associated with mental retardation. Thus assessment of antiproliferative activity of anticonvulsant drugs may be one criterion for identification of teratogenic potential during neurulation.

Animals↗
PubMed1990

Antihistaminic activity of pulegone on the guinea-pig ileum.

Pulegone, a natural monoterpene compound, has an antihistamine effect on guinea-pig ileum. Its antagonism is of the competitive type (PA2 = 6.35) like that of mepyramine and dexchlorpheniramine, two H1-antagonists, with PA2 values of 10.15 and 8.74, respectively.

Animals↗
PubMed1989

Pharmacological study of certain extracts of Laurobasidium lauri.

On the basis of observational screening in conscious rats, the essential oil of Laurobasidium lauri seems to be the main agent responsible for the sedating and analgesic effects of this fungus. The inhibitory activity observed in isolated rat uterus with the butanol and alkaloid-rich fractions of this species appears to be related to a decrease in the calcium available for contraction.

Acetylcholine↗
PubMed1989

Health education: special issues for older adults.

The older adult population in the United States has grown substantially since the turn of the century. With extended longevity and the relatively good functional status of most older adults, prevention programs that identify and intervene on risk factors in older adults may be an effective means to dealy ill health. The availability of data to guide both the selection and evaluation of prevention services for older adults, however, is strikingly limited in virtually all areas. Until recently, all persons over the age of 65 were treated as a single category of older adults although the older population is very heterogeneous. Most agree that prevention and education for this age group should focus on the prevention of disease, maintenance of existing abilities, and on prevention of deterioration of impairments that result in dysfunction or handicap. The most effective methods for developing behavioral intervention strategies may result from an integration of the behavioral diagnostic framework and current value expectancy and social learning theories. Health education interventions based on these strategies can be very effective in older age groups in terms of both improving adherence behavior with therapeutic and prevention intervention, and potentially in reducing morbidity and excess mortality.

Aged↗
PubMed1988

The anticonvulsant sodium valproate specifically induces the expression of a rat glial heat shock protein which is identified as the collagen type IV receptor.

A potential mechanism for valproate (VPA)-induced increases in glial cell-substratum adhesivity has been demonstrated. Metabolically labelled glioma (C6) and primary astrocytes showed a statistically significant accumulation of protein when cultured in the presence of therapeutic concentrations of VPA (1 mM). This was mainly accounted for by a 10-fold increase in the production of a single polypeptide of 43 kDa molecular weight. Fractionation studies and metabolic labelling with N-acetyl-D-mannosamine showed this to be a sialoglycoprotein which was plasma membrane-bound. VPA-induction of the polypeptide was apparently specific to glioma and primary astrocytes and was not observed in neuroblastoma (neuro-2a), fibroblasts (3T3), pituicytes (GH3) and epithelial cells (NCTC). The 43 kDa component of glia was demonstrated to be the receptor for type IV collagen by binding metabolically labelled and solubilised cells to Sepharose beads which had been individually coated with laminin, fibronectin and type IV collagen. The protein has also been shown to be a heat shock product as metabolically labelled glioma showed a 10-fold increase in its expression when cultured at 42 degrees C. This heat shock induced expression was transient and was in marked contrast to that seen with VPA where it increased with time and was sustained. The expression of 43 kDa is suggested to arise by VPA and heat shock induced delays in cell cycle progression and this is discussed in relation to teratogenic action.

Anticonvulsants↗