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Biomedical subjects

J Arnold

Publications and source records attributed to J Arnold.

At least 199 records · Page 11Linked to original sources
PubMed1986

Exercise suppression of thermoregulatory thermogenesis in warm- and cold-acclimated rats.

An evaluation was made of the effects of an acute exercise bout on nonshivering thermogenesis (NST) in cold-acclimated rats (4 degrees C for 6 weeks) and shivering thermogenesis in 24 degrees C-acclimated rats (24 degrees C for 6 weeks). Assessment techniques included indirect calorimetry during treadmill running and brown adipose tissue (BAT) mitochondrial guanosine diphosphate (GDP) binding immediately following a treadmill run. Calorimetric results for 24 degrees C-acclimated rats running at 4 degrees C indicated total substitution of shivering thermogenesis by exercise-derived heat. No difference in GDP-binding, an index of BAT nonshivering thermogenic activity, was observed between exercised and nonexercised 24 degrees C-acclimated rats. Calorimetric results for cold-acclimated rats running at 4 degrees C indicated a total suppression in the energy cost associated with NST, exercise-derived heat replacing or substituting for NST. Examining BAT properties in the exercised cold-acclimated rats revealed a significant 40% decrease in BAT mitochondrial GDP-binding. These results suggest that during running, metabolic heat due to the exercise totally replaces shivering in 24 degrees C-acclimated rats and totally replaces BAT nonshivering thermogenesis in cold-acclimated rats.

Acclimatization↗
PubMed1986

Lipoprotein lipase in adipose tissues of exercise-trained, cold-acclimated rats.

The combined effects of exercise training and cold acclimation on serum lipids and on the activity of lipoprotein lipase (LPL) in epididymal white (WAT) and interscapular brown adipose tissues (BAT) of the rat were evaluated. Sedentary and exercise-trained (treadmill) rats were housed and trained at either 24 or 4 degrees C for 45 days. Although neither treatment given alone influenced serum total cholesterol, exercise training in the cold resulted in a 54% increase in this variable. Serum triglycerides were lowered to 80% of control values by exercise training and to 44% of control by cold acclimation. Both treatments resulted in lower insulin and thyroxine concentrations, while triiodothyronine levels were unaffected. Total LPL activity in WAT was increased twofold by exercise training at both temperatures, whereas cold acclimation stimulated WAT LPL activity to a lesser extent. Exercise training had no overall effect on LPL activity of BAT, whereas cold acclimation increased the latter in both sedentary (217%) and trained (420%) animals. These results emphasize the potential importance of LPL-mediated lipid assimilation in the metabolic events that lead to energy production in response to environmental stresses and lend support to the notion that the regulation of LPL activity is tissue specific.

Acclimatization↗
PubMed1986

Energy balance in exercise-trained rats acclimated at two environmental temperatures.

The present study was carried out to investigate the effects of exercise training on energy balance in male rats acclimated at two different environmental temperatures. Sedimentary and exercised rats were housed and trained at either 24 or 4 degrees C, with the training program consisting of running on a motor-driven treadmill within their respective environments. After 45 days, energy, protein, and fat contents of rats were determined together with the energy content of food and feces. The results show that metabolizable energy intake was reduced by 10% in exercise-trained groups. Substantial differences in energy gains were observed between sedentary and trained rats; sedentary rats showed almost three times more energy gain than trained rats. Carcass analysis revealed the energy gain differences to be mainly due to varied amounts of fat deposition. Energy expenditure (kJ) excluding the cost of exercise training was corrected for metabolic body size (BW 0.75), which in turn showed no significant differences between trained rats and their respective sedentary controls. The present results suggested that exercise training in rats leads to neither increase nor decrease in energy expenditure through components additional to physical activity. The present results also indicated that brown adipose tissue thermogenesis, as assessed through mitochondrial guanosine 5'-diphosphate binding, was not significantly modified by exercise training, regardless of the temperature at which the rats were housed and trained.

Acclimatization↗
PubMed1986

Gastric ulcer: a double-blind comparison of 100 mg pirenzepine plus antacid versus 800 mg cimetidine plus antacid.

Fifty-five patients with endoscopically confirmed gastric ulcers received either cimetidine (28 patients) or pirenzepine (27 patients) in a randomized double-blind manner. Fifty-seven per cent of the patients treated with cimetidine and 48% of those treated with pirenzepine presented with endoscopically healed ulcers after 4 weeks of treatment. By 8 weeks complete healing had occurred in 83% of the patients taking cimetidine and 76% of those taking pirenzepine. These differences were not statistically significant. Severity of pain on entering the study was correlated with slower healing of the ulcer. Side effects occurred in 5 of 27 patients in the pirenzepine group and 3 of 28 in the cimetidine group. They were mostly mild and did not differ from side effects observed in other studies.

Antacids↗
PubMed1986

Comparison of the use of isotopic proline vs leucine to measure protein synthesis in cultured fibroblasts.

Compartmentation of the amino acid precursor pools for protein synthesis in cultured cells can substantially complicate measurements of synthesis rates. This is particularly true for nonessential amino acids such as proline, an amino acid often used in isotopic form to measure collagen synthesis. We have made a comparative study of this problem in cultured IMR-90 fibroblasts using isotopic proline and leucine to measure total protein and collagen synthesis. 3H-leucine in the extracellular (EC) medium equilibrates with tRNA-leucine at an EC concentration of 0.4 mM in both dividing and stationary cells. Thus, under these experimental conditions there is no complicating compartmentation of leucine for protein synthesis. Equilibration of EC and tRNA-bound 3H-proline, however, does not occur even when the EC concentration is in the mM range, based upon simultaneous measurements of synthesis rates using 3H-proline and 3H-leucine together. Furthermore, significant changes in EC proline concentration and specific activity occur over short time intervals (2 hr) if the initial EC proline concentration is below 0.2 mM. Thus, the use of isotopic proline to measure protein synthesis introduces substantial interpretive problems. Serum deprivation causes changes in both total collagen synthesis and the percent of protein synthesis devoted to collagen when measured with either 14C-leucine or 3H-proline. At the same time, isotopic proline remains the better choice for measuring percent collagen synthesis.

Carbon Radioisotopes↗
PubMed1986

Statistics of natural populations. III. Sequential sampling plans for the estimation of gene frequencies.

In previous work several models have been developed for genetic surveys of natural populations. Parents of unknown genotype are collected from a natural population, polymorphic at a single genetic locus. From each of these N cryptic parents a number of offspring are identified for their genotype. Our problem is to select an efficient offspring sampling plan for estimating the frequency of an allele in the cryptic adult population based on the N family profiles of juvenile genotypes. A criterion called the information per unit cost of observation is introduced to evaluate sequential sampling plans, in which the number of offspring per family examined is random. Some simple, practical schemes for stopping the sampling of offspring from a collected parent are introduced; one example is stopping when: (i) the offspring are definitive about the parental genotype(s) for the first time; (ii) a fixed number of one genotype only is seen; or (iii) a fixed maximum feasible number of offspring have been genotyped. This sampling scheme is recommended. For each sampling scheme, the best linear unbiased estimator and the sequential maximum likelihood estimator of the allele frequency are characterized. From the moments of these estimators, it is then possible to tabulate efficient sequential sampling plans, which are better (in the sense of information per unit cost), just as simple, and less costly than corresponding fixed sampling plans in use.

Alleles↗
PubMed1985

Effect of a cold stimulus on the synthesis of uncoupling protein in brown adipose tissue of rats and newborn rabbits.

Rats are known to respond to a cold stimulus by increasing the activity and amount of the uncoupling protein in brown adipose tissue. A 48 h cold stimulus was found to increase the synthesis of uncoupling protein 3.8-fold in 4-5 week old rats whereas no change was observed with newborn rabbits. The lack of response in the latter case may reflect a difference between rabbits and rats or that synthesis is already maximal in newborn rabbits.

Adipose Tissue, Brown↗
PubMed1985

Pulmonary thromboemboli after neonatal asphyxia.

Two surviving neonates with pulmonary thromboembolism, diagnosed by ventilation-perfusion lung scan, are described. Both infants had respiratory distress, and one had features consistent with persistent pulmonary hypertension of the neonate. These reports demonstrate that substantive pulmonary emboli can occur in neonates and may not be recognized without an appropriate level of clinical suspicion.

Asphyxia Neonatorum↗
PubMed1985

Synthesis of cytoskeletal and contractile proteins by cultured IMR-90 fibroblasts.

Models of the assembly of cytoskeletal and contractile proteins of eukaryotic cells require quantitative information about the rates of synthesis of individual component proteins. We applied the dual isotope technique of Clark and Zak (1981, J. Biol. Chem., 256:4863-4870) to measure the synthesis rates of cytoskeletal and contractile proteins in stationary and growing cultures of IMR-90 fibroblasts. Fibroblast proteins were labeled to equilibrium with [14C]leucine over several days, at the end of which there was a 4-h pulse with [3H]leucine. Fractional synthesis rates (percent per hour) were calculated from the 3H/14C ratio of cell protein extracts or protein purified by one- or two-dimensional polyacrylamide gel electrophoresis and the 3H/14C ratio of medium-free leucine. The average fractional synthesis rate for total, SDS- or urea-soluble; Triton-soluble; and cytoskeletal protein extracts in stationary cells each was approximately 4.0%/h. The range of values for the synthesis of individual proteins from total cell extracts or cytoskeletal extracts sliced from one-dimensional gels was similar, though this range was greater than that for major proteins of Triton-soluble protein extracts. Three specific cytoskeletal proteins--actin, vimentin, and tubulin--were synthesized at similar rates that were significantly slower than the average fractional synthesis rate for total protein. Myosin, on the other hand, was synthesized faster than average. Synthesis rates were the same for beta-and gamma-actin and polymerized (cytoskeletal extract) vs. Triton-soluble actin. The same was true for alpha- and beta-tubulin and two different forms of vimentin. Synthesis rates were uniformly higher in growing cells, though the same pattern of differential rates was observed as for stationary cells. Synthesis rates in growing cells were higher than the rate necessary to maintain the growth rate, even for those cytoskeletal proteins being synthesized slowly. Therefore, there appears to be some turnover of these cytoskeletal elements even during growth. We conclude that proteins in cytoskeletal extracts may have nonuniform rates of synthesis, but at least one important subclass of cytoskeletal proteins that comprise filament subunits have the same synthesis rates.

Actins↗
PubMed1985

Immunological studies of the uncoupling protein of brown adipose tissue.

The immunological relationship of the uncoupling protein from brown adipose tissue of several mammalian species was examined by using a rabbit antibody preparation against the rat protein. Complete cross-reactivity of the antibody to the protein from hamster, mouse, and rat was found, whereas the protein from rabbit cross-reacted only 25%. Cross-reactivity was also found with the human uncoupling protein, although the human protein was found to be about 1 kdalton smaller than the rat protein. No protein of the size of the uncoupling protein was detected in several tumor cell lines examined.

Adipose Tissue, Brown↗
PubMed1985

Registered dental hygienists as dental students.

Surveys were conducted to (1) investigate how and why dental hygienists choose to become dentists, (2) evaluate their success in dental school, (3) assess the experience of those who had entered dental school, and (4) gauge the level of interest among dental hygienists and currently enrolled dental hygiene students in applying to dental school. Records of former dental hygienists who had earned a dental degree indicated that the majority performed above class averages and that none withdrew or were dismissed from school. Those enrolled in dental school agreed that prior dental hygiene experience was an asset in laboratory and clinical work; they were less certain about any academic advantage. Registered and student dental hygienists generally agreed on the attractive and unattractive aspects of becoming a dentist. Major attractions cited were increased earnings and independence; major drawbacks were the costs of dental education and stress associated with being a dentist. Those with baccalaureate degrees showed more interest in becoming dentists than did those with associate degrees. Dental schools should give dental hygienists positive consideration as applicants and advanced placement as students. In view of the observed interest in career change, dental hygiene and dental programs are encouraged to develop more sensitive career counseling.

Career Choice↗
PubMed1984

[Treatment of stomach ulcers with cimetidine and pirenzepine].

37 patients with endoscopically confirmed gastric ulcers received either cimetidine (19 patients) or pirenzepine (18 patients) in a double-blind trial. At 4 weeks, 53% of the patients treated with cimetidine and 44% of those treated with pirenzepine had endoscopically healed ulcers. At 8 weeks, complete healing had occurred in 83% of the patients taking cimetidine and 71% of those taking pirenzepine. These differences are not statistically significant.

Anti-Ulcer Agents↗
PubMed1984

Demographic influences on mitochondrial DNA lineage survivorship in animal populations.

Probability models of branching processes and computer simulations of these models are used to examine stochastic survivorship of female lineages under a variety of demographic scenarios. A parameter II, defined as the probability of survival of two or more independent lineages over G generations, is monitored as a function of founding size of a population, population size at carrying capacity, and the frequency distributions of surviving progeny. Stochastic lineage extinction can be very rapid under certain biologically plausible demographic conditions. For stable-sized populations initiated by n females and/or regulated about carrying capacity k = n, it is highly probable that within about 4n generations all descendants will trace their ancestries to a single founder female. For a given mean family size, increased variance decreases lineage survivorship. In expanding populations, however, lineage extinction is dramatically slowed, and the final k value is a far more important determinant of II than is the size of the population at founding. The results are discussed in the context of recent empirical observations of low mitochondrial DNA (mtDNA) sequence heterogeneity in humans and expected distributions of asexually transmitted traits among sexually reproducing species.

Animals↗
PubMed1984

Computer-aided digitisation of fundus photographs.

A method is described for the analysis of standard retinal colour photographs with the facility to compare accurately photographs taken serially, thus yielding information on the change in the retinal disease over a period of several years. The reproducibility of placement of a microaneurysm on the same photograph by the same observer is equivalent to +/- 6.6 microns at the retina and inter-observer variation is equivalent to +/- 7.2 micron at the retina. Overall accuracy of placement of a point is 10 micron at the retina.

Aneurysm↗
PubMed1984

Organophosphate detoxification related to induced hepatic microsomal enzymes of chickens.

Detoxification of the organophosphate malathion in its activated form (malaoxon) was increased in livers of chickens given microsomal enzyme inducers (beta-naphthoflavone, 3-methylcholanthrene, butylated hydroxytoluene (BHT), or polychlorinated biphenyls). Positive correlations between inducer and microsomal enzyme activity were demonstrated for beta-naphthoflavone with demethylation of p-nitroanisole and for 3-methylcholanthrene and for BHT with cytochrome P450/448 and cytochrome b5. Malaoxon detoxification decreased in correlation with decreases in quantities of cytochrome P450/448 in birds fed a low-protein diet. Prediction of malaoxon detoxification was aided by using enzyme activities as dependent variables in the regression model, although only in birds given BHT were all of the 5 enzymes necessary for providing the best predictive model.

Animals↗
PubMed1983

[Dissolution of gallstones based on 6 months treatment with a single daily dose of ursodeoxycholic acid].

51 patients with radiolucent gallstones of diameter less than or equal to 15 mm were treated for 6 months with a new form of ursodeoxycholic acid (UDCA) in a single dose of 450 mg at bedtime. This new form has 3 components with fractionate liberation. The rate of partial and complete dissolution after 6 months was 63.4%, reaching 85% for gallstones of less than 5 mm diameter. The results show that a single dose of 450 mg UDCA at bedtime is as effective as UDCA at mealtimes in the dissolution of radiolucent gallstones. Administration of the drug once a day should be more acceptable to patients.

Cholelithiasis↗