Age-dependent enzyme changes in Drosophila melanogaster.
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Aging↗
Biomedical subjects
J C Hall
Publications and source records attributed to J C Hall.
Effect of aldosterone on liver mitochondria isolated from adrenalectomized rats.
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Adenosine Triphosphatases↗
Employment problems of schizophrenic patients.
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Community Mental Health Services↗
Two-dimensional gel electrophoretic analysis of rat sperm membrane interaction with cauda epididymal fluid.
Two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) was used to analyze the polypeptide composition of rat cauda epididymal fluid, blood serum and membrane-enriched fractions of caput, corpus, and cauda epididymal spermatozoa. Several polypeptides were found in both cauda fluid and blood serum, and in both cauda fluid and epididymal spermatozoa. Prominent cauda epididymal fluid polypeptides that were associated with caput, corpus, and cauda sperm membranes were 32 and 33 kDa. Passage of spermatozoa from the caput to the cauda epididymidis was characterized by the loss of three glycopolypeptides of 32, 30 and 29 kDa, and by the addition of a 37-kDa glycopolypeptide. Incubation of intact caput, corpus and cauda spermatozoa with cauda epididymal fluid revealed major changes in the polypeptide maps of the incubation fluid and the membrane-enriched fractions of caput and corpus, but not cauda spermatozoa. The incubation of cauda fluid with caput and corpus sperm cells was characterized by a loss of several polypeptides and the addition of a 24-kDa glycopolypeptide. The most striking change in spermatozoa incubated with cauda epididymal fluid was the addition of two glycopolypeptides of 32 and 33 kDa to the polypeptide maps of caput sperm cells. These data demonstrate that rat spermatozoa undergo surface modifications during epididymal maturation and that these modifications can be influenced by epididymal fluid.
Animals↗
GABAergic inhibition shapes frequency tuning and modifies response properties in the superior olivary nucleus of the leopard frog.
The role of gamma-aminobutyric acid (GABA)ergic inhibition in shaping the excitatory frequency tuning of 74 neurons in the superior olivary nucleus of the leopard frog, Rana pipiens, was studied using iontophoretic application of the GABA(A) receptor antagonist, bicuculline methiodide. For 37 neurons, bicuculline application broadened and/or changed the configuration of the excitatory frequency-tuning curve. Results indicate that GABA-mediated inhibition not only sharpens the tuning curves of neurons but also plays a critical role in creating new frequency tuning properties in the superior olivary nucleus. Bicuculline application affected other neuronal response properties as well. Spontaneous firing rate increased 11-338% for 18 of 59 neurons. For 32 of 58 neurons there was an increase in stimulus-evoked discharge rate and a change in rate-level function. There was no qualitative effect on the discharge pattern of 60 neurons, though 2 tonically responding neurons did show an increase (> 30%) in response duration. Additional roles for GABAergic inhibition in monaural signal analysis are discussed.
Acoustic Stimulation↗
The Voyager Interstellar Mission.
The Voyager Interstellar Mission began on January 1, 1990, with the primary objective being to characterize the interplanetary medium beyond Neptune and to search for the transition region between the interplanetary medium and the interstellar medium. At the start of this mission, the two Voyager spacecraft had already been in flight for over twelve years, having successfully returned a wealth of scientific information about the planetary systems of Jupiter, Saturn, Uranus, and Neptune, and the interplanetary medium between Earth and Neptune. The two spacecraft have the potential to continue returning science data until around the year 2020. With this extended operating lifetime, there is a high likelihood of one of the two spacecraft penetrating the termination shock and possibly the heliopause boundary, and entering interstellar space before that time. This paper describes the Voyager Interstellar Mission--the mission objectives, the spacecraft and science payload, the mission operations system used to support operations, and the mission operations strategy being used to maximize science data return even in the event of certain potential spacecraft subsystem failures. The implementation of automated analysis tools to offset and enable reduced flight team staffing levels is also discussed.
Astronomy↗
2,4-Dichlorophenoxyacetic acid residues in semen of Ontario farmers.
Although paternal exposures to environmental toxicants probably play a role in adverse pregnancy outcomes, few data are available on the extent of this exposure. One semen and two 24-h urine samples were collected from 97 Ontario farmers who had recently used the phenoxy herbicides 2,4-D (2.4-dichlorophenoxyacetic acid) and/or MCPA ([4-chloro-2-methylphenoxyl acetic acid). Both samples were analyzed for 2,4-D using an immunoassay-based technique. Approximately 50% of the semen samples had detectable levels of 2, 4-D (> or =5.0 pph (ng/mL)). Semen levels of 2.4-D were correlated more closely with the second of the two urine samples. Although several studies have measured 2.4-D in the urine of applicators, this study is the first to attempt to measure 2,4-D levels in semen. As these pesticides can be excreted in the semen, they could be toxic to sperm cells and be transported to the woman and developing embryo/fetus. Further research is needed to understand how pesticide handling practices can affect semen pesticide residues and the relationship between the levels observed and reproductive health.
2,4-Dichlorophenoxyacetic Acid↗
Research: the way to quality care.
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Humans↗
Starvation alters the activity and mRNA level of glutaminase and glutamine synthetase in the rat intestine.
The metabolism of glutamine, the main respiratory fuel of enterocytes, is governed by the activity of glutaminase and glutamine synthetase. Because starvation induces intestinal atrophy, it might alter the rate of intestinal glutamine utilization. This study examined the effect of starvation on the activity, level of mRNA, and distribution of mRNA of glutaminase and glutamine synthetase in the rat intestine. Rats were randomized into groups and were either: (1) fed for 2 days with rat food ad libitum or (2) starved for 2 days. Standardized segments of jejunum and ileum were removed for the estimation of enzyme activity, level of mRNA, and in situ hybridization analysis. The jejunum of the fed rats had a greater activity of both enzymes per centimeter of intestine (P < 0.01), a greater glutaminase specific activity (1.97 +/- 0.45 vs. 1.09 +/- 0.34 micromol/hr/mg protein, P < 0.01), and a lower level of glutaminase and glutamine synthetase mRNA. The ileum of the fed rats had a greater activity of glutamine synthetase per centimeter of intestine (162.9 +/- 50.6 vs. 91.0 +/- 23.1 nmol/hr/cm bowel, P < 0.01), a lower level of glutaminase mRNA, and a greater level of glutamine synthetase mRNA. In situ hybridization analysis showed that starvation does not alter the distribution of glutaminase and glutamine synthetase mRNA in the intestinal mucosa. This study confirms that starvation decreases the total intestinal activity per centimeter of both glutaminase and glutamine synthetase. More importantly, the results indicate that the intestine adapts to starvation by accumulating glutaminase mRNA. This process prepares the intestine for a restoration of intake.
Journal Article↗
The role of glutaminase in the small intestine.
Glutaminase is the enzyme which hydrolyses glutamine, the main respiratory fuel of the intestine, to yield glutamate and ammonia. Glutaminase has a central role in intestinal metabolism: the products of the reaction catalyzed by glutaminase can be transaminated, catabolized to yield energy or used for the biosynthesis of pyrimidine nucleotides. Experimental treatments which deprive the intestine of glutamine induce intestinal atrophy. In this review, attention is paid to the role of glutaminase in intestinal metabolism. Background information on the structure, kinetics and distribution of glutaminase precede a discussion of the metabolism of glutamine within the intestine. In closing, we review the factors known to regulate glutaminase activity and emphasise that the regulation of glutaminase within the intestine is poorly understood.
Caco-2 Cells↗
Action potential mutations stop a biological clock in Drosophila.
The Drosophila melanogaster male produces a species-specific courtship song by wing vibration. The most conspicuous feature of the song is a series of pulses with a 30-40-ms interpulse interval (IPI) which oscillate in wild-type males with a period of 50-60 s. This short-term biological rhythm in IPI is influenced by several gene mutations at the period (per) locus, which alter the normal 24-h free-running period of the circadian clock and have corresponding effects on the song cycle. The present study reveals that, under restrictive conditions, temperature-sensitive mutations which affect neuronal membrane excitability seem to stop the biological clock underlying the fruitfly's song rhythm.
Action Potentials↗
A family of unusually spliced biologically active transcripts encoded by a Drosophila clock gene.
Complementary DNA cloning of the transcripts of the Drosophila clock gene period reveals three distinct transcripts. These result from unusual splicing pathways, one involving a CG 3' splice site and one resulting in the use of two different reading frames in one exon, and they predict three separate proteins. Two of the cloned cDNAs can restore clock function to mutant arrhythmic flies.
Animals↗
Behaviour modification by in vitro mutagenesis of a variable region within the period gene of Drosophila.
The period gene of Drosophila melanogaster, implicated in the control of both the circadian and male courtship song rhythms, is found to be polymorphic. Alleles differ in the length of a region of the gene encoding a series of threonine-glycine repeat units. The phenotypes of transformed fruit flies, in which the only functional period gene lacks the entire perfect threonine-glycine repeat region, show that the effects of the period gene on the circadian and male courtship song rhythms can be dissociated.
Alleles↗
The evaluation of wound infection after arterial surgery.
Many of the wound infections that occur after arterial surgery require prolonged attention with frequent changes of dressings. However, the traditional way of reporting wound infections is to only declare the overall incidence of this adverse event. In this study, we have evaluated 302 patients undergoing arterial surgery to determine the relationship between the incidence of wound infection, the length of time that wounds were dressed, and the results of a modified ASEPSIS wound scoring system. The overall incidence of wound infection was 14% (43/302). It was noted that patients with high wound scores had a correspondingly high incidence of conventionally defined wound infections; and, in addition, such patients required dressing changes over prolonged periods. It is concluded that the documentation of both the duration of wound dressings and a wound scoring system are useful tools when evaluating the outcome of patients after arterial surgery.
Aged↗
Analysis of conditioned courtship in dusky-Andante rhythm mutants of Drosophila.
Genetic connections between learning and rhythmicity were suggested to have been established in a previous study, in part because the duskyAndante (dyAnd) mutation in Drosophila disrupted both behaviors. dyAnd, isolated as a slow-clock variant, was reported to cause an approximately fourfold decrement in courtship-suppression conditioning. These effects have been reexamined; the experiments were buttressed by testing the effects of several recently isolated mutations at the dusky locus, along with the original And Allele that had been induced there. The reexamination was also prompted by anatomical concerns, certain of which have recently focused on dy-induced decrements in cell size, but only in terms of wing morphology. Another anatomical issue involves the discovery of a neuronal pathway that seems to connect circadian pacemaker cells to a structure in the Drosophila brain that is involved in learning. In observer-blind experiments, however, it was found that neither pacemaker-slowing (Andante-like) dy mutations nor others that cause no rhythm defects produced subnormal conditioned courtship. Moreover, in the adult brain of a slow-clock dyAnd mutant, no axonal pathway defects were readily discernible and putative pacemaker neurons appeared to be normal in size.
Animals↗
Use of internal validity in the construct of an index of undernutrition.
An index of undernutrition (IOU) has been developed from a crosssectional study of 200 general surgical patients. The IOU was constructed using a ranking method based upon the relative values of anthropometric measurements (weight loss, mid-arm muscle area, mid-arm fat area) and serum protein concentrations (albumin, transferrin). The IOU was derived without reference to the incidence of adverse clinical events and took the form of a boolean cluster. A subsequent prospective longitudinal study evaluated the IOU in 367 general surgical patients at the time of admission to hospital. The results of this study supported the validity of the IOU. There was no association between gender and IOU scores. However, patients with high scores were more likely to be elderly (p less than 0.02), have cancer (p less than 0.001), stay in hospital longer (p less than 0.001), or experience an adverse clinical event after surgery (p less than 0.001). In accord with other published indices of undernutrition, the association between the extent of undernutrition and the incidence of adverse clinical events was only of moderate diagnostic potential (overall accuracy 68%). This study demonstrates that it is possible to derive an index of protein-energy undernutrition that is independent of the incidence of adverse clinical events.
Adult↗
Glycine.
Glycine consists of a single carbon molecule attached to an amino and a carboxyl group. Its small size helps it to function as a flexible link in proteins and allows for the formation of helices, an extracellular signaling molecule, recognition sites on cell membranes and enzymes, a modifier of molecular activity via conjugation and glycine extension of hormone precursors, and an osmoprotectant. There is substantial experimental evidence that free glycine may have a role in protecting tissues against insults such as ischemia, hypoxia, and reperfusion. This impressive catalogue of functions makes an interesting contrast with glycine's perceived metabolic role as a nonessential amino acid. Glycine interconverts with serine to provide a mechanism for the transfer of activated one-carbon groups. Glycine has just been viewed as a convenient source of nitrogen to add to solutions of nutrients. Although this may have unexpected benefits when such solutions are used in clinical practice, it does raise the specter of a possible confounding effect in experiments when glycine is added to control solutions to make them isonitrogenous.
Animals↗
Seasonal leaching and biodegradation of dicamba in turfgrass.
The leaching of surface-applied herbicides, such as dicamba (2methoxy-3,6-dichlorobenzoic acid), to ground water is an environmental concern. Seasonal changes in soil temperature and water content, affecting infiltration and biodegradation, may control leaching. The objectives of this study were to (i) investigate the leaching of dicamba applied to turfgrass, (ii) measure the degradation rate of dicamba in soil and thatch in the laboratory under simulated field conditions, and (iii) test the ability of the model EXPRES (containing LEACHM) to simulate the field transport and degradation processes. Four field lysimeters, packed with sandy loam soil and topped with Kentucky bluegrass (Poa pratensis L.) sod, were monitored after receiving three applications (May, September, November) of dicamba. Concentrations of dicamba greater than 1 mg L(-1) were detected in soil water. Although drying of the soil during the summer prevented deep transport, greater leaching occurred in late autumn due to increased infiltration. From the batch experiment, the degradation rate for dicamba in thatch was 5.9 to 8.4 times greater than for soil, with a calculated half-life as low as 5.5 d. Computer modeling indicated that the soil and climatic conditions would influence the effectiveness of greater degradation in thatch for reducing dicamba leaching. In general, EXPRES predictions were similar to observed concentration profiles, though peak dicamba concentrations at the 10-cm depth tended to be higher than predicted in May and November. Differences between predictions and observations are probably a result of minor inaccuracies in the water-flow simulation and the model's inability to modify degradation rates with changing climatic conditions.
Biodegradation, Environmental↗