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Biomedical subjects

J C Hall

Publications and source records attributed to J C Hall.

At least 181 records · Page 10Linked to original sources
PubMed1992

An immunoassay for metolachlor detection in river water and soil.

An indirect enzyme-linked immunosorbent assay (EIA) for metolachlor (2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamid e) detection in river water and soil was developed using serum obtained from rabbits immunized against the acid of metalaxyl ((N-(2,6-dimethylphenyl)-N-(methoxy-acetyl)-DL-alanine methyl ester) conjugated to bovine serum albumin. The assay had a linear working range from 1 to 50 ng/ml with a mean I50 value of 13.6 ng/ml and a lower detection limit of 2.0 ng/ml. Both the mean interwell and interassay coefficients of variation were less than 4% over the range of the standard curves for samples which had been prepared in phosphate buffered saline (PBS), river water, or soil extract. Assay cross-reactivity to the following four structurally related chloro-acetanilide pesticides were: propachlor (0%), metazachlor (0%), alachlor (23%), and metalaxyl (5,000%). Mean recoveries of metolachlor in spiked (2.0 to 32.0 ng/ml range) PBS, river water, and soil extract were 102%, 103%, and 110%, respectively. Soil samples were taken over a 56-d period from field plots treated with metolachlor and analyzed by GC and EIA. The correlation coefficient for comparison of the two methods was 0.96 with the slope of the linear regression line being 0.78. Furthermore, no statistical difference (P less than 0.05) was found between the dissipation curves of metolachlor derived from GC data versus EIA data.

Acetamides↗
PubMed1992

Selective embolisation of intrahepatic aneurysms.

The radiological techniques that can be used to selectively embolise small arteries have improved markedly in the past few years. This article discusses the use of transcatheter embolisation in the management of three patients with aneurysms involving the intrahepatic arterial tree.

Adult↗
PubMed1992

Effects of a simulated microgravity model on cell structure and function in rat testis and epididymis.

A tail-suspension (TS) rat model used to simulate microgravity was tested for its effects on the anatomy, cell structure, and function of the testis and epididymis in sexually mature male rats. Rats suspended for 7 days without inguinal canal ligation exhibited a significant (P less than or equal to 0.05) reduction in testis weight compared with controls (1.55 +/- 0.04 to 1.1 +/- 0.02 g). Except for the liver, epididymis, and adrenals of TS rats and TS rats allowed to recover for 7 days, no significant (P less than or equal to 0.05) change was observed in the weight of other body and accessory sex organs. A histological examination of the testes and epididymides of model animals revealed disorganized seminiferous tubules and accumulation of large multinucleated cells and spermatids in the lumen of the epididymis. A significant (P less than or equal to 0.05) increase in serum luteinizing hormone (53.1 +/- 6.7 to 66.2 +/- 10.1 ng/ml) and follicle-stimulating hormone (257 +/- 25 to 305 +/- 38 ng/ml) was observed in TS nonligated rats, whereas serum prolactin and testosterone levels were observed to decline from 8.3 +/- 1.3 to 5.1 +/- 0.29 and 7.1 +/- 1.3 to 3.8 +/- 0.25 ng/ml, respectively. Decreases in testis protein content and testosterone levels of the testis, interstitial fluid, and epididymis were also observed in model animals. These data demonstrate that the suspension procedure used in the National Aeronautics and Space Administration TS model results in the testis and epididymis translocating into the abdominal cavity, causing cellular degeneration and organ dysfunction.

Animals↗
PubMed1992

Mapping the clock rhythm mutation to the period locus of Drosophila melanogaster by germline transformation.

The Clock (Clk) mutation shortens circadian rhythms of locomotor activity and eclosion from ca. 24 h to 22.5-23 h. Clk was previously mapped, by meiotic recombination, very close to the period(per) locus on the X chromosome. To determine whether Clk is a mutation within the per gene or if the former is separate from the latter, two overlapping genomic fragments were cloned from Clk flies to produce a per-containing 13.2 kb construct, per01 flies (which by themselves are arrhythmic)--when transformed with this construct--expressed short-period rhythms. This indicates that the Clk mutation is contained within this 13.2 kb region and is almost certainly a new "fast-clock" allele of per.

Alleles↗
PubMed1992

The analysis of new short-period circadian rhythm mutants suggests features of D. melanogaster period gene function.

A number of new period gene (per) mutants were generated by in vitro mutagenesis and germ line transformation. Missense mutations were made at amino acid 589, which is altered in the 19 h short-period (per(s)) mutant, and insertion mutations were generated with peptides commonly used for epitope tagging. Most of these new per mutants had short behavioral rhythms. Flies with heteroallelic combinations of these new mutant per genes were found to have "hybrid" periods, i.e., they had values that were usually in between those of the individual alleles. These findings suggest that short-period per mutants are not unusual gain-of-function mutants but rather more traditional loss-of-function mutants that are unable to influence the circadian pacemaker in a proper manner. The data also suggest that the per protein may engage in important intermolecular interactions.

Animals↗
PubMed1992

An antibody to the Drosophila period protein labels antigens in the suprachiasmatic nucleus of the rat.

Cell bodies in the rat suprachiasmatic nucleus (SCN) were labeled with an antibody against a small domain of the period (per) protein, the product of a gene in Drosophila that regulates circadian rhythms. In immunoblots of SCN protein extracts, the antibody recognized a band of approximately 115 kD, as well as a heterogeneous antigen ranging from 160 kD to 170 kD. The antibody was found in previous studies to label putative circadian pacemaker neurons in Aplysia and Bulla, as well as the cellular sites of per expression in flies. Taken together, these results suggest that the region of the per protein recognized by this antibody may be widely conserved in neuronal circadian pacemakers.

Animals↗
PubMed1992

Expression of the period clock gene within different cell types in the brain of Drosophila adults and mosaic analysis of these cells' influence on circadian behavioral rhythms.

The product of the period (per) gene of Drosophila melanogaster is continuously required for the functioning of the circadian pacemaker of locomotor activity. We have used internally marked mosaics to determine the anatomical locations at which per expression is required for adult rhythmicity, and thus where the fly's circadian pacemaker is likely located in this holometabolous insect. We first provide a detailed description of the distribution and nature of per-expressing cells in the fly's CNS. Using an antibody to the per gene product, or to that of a reporter of per expression, in conjunction with an antibody to the embryonic lethal-abnormal visual system (elav) gene product--which is used as a marker of neuronal identity--we have experimentally confirmed previously proposed assignments of per-expressing cells to the neuronal and glial classes. Thus, we found that per expression and elav immunoreactivity colocalized in large cells located in the lateral cortex of the central brain, as well as in more dorsally located cells in the posterior central brain. In contrast, we found that cells located at the margins of the cortex and the neuropil, and within the neuropil, as well as smaller cortical cells found throughout the brain's cortex, were elav negative, supporting the notion that they are glial in nature. Using internally marked mosaics, we find that the pacemaker is located in brain but is not exclusive to the eyes, the ocelli, or the optic lobes, which is consistent with previous reports obtained in this and other insects of this class. Although the pacemaker may be a paired structure, we show that the functioning of one of them is sufficient for rhythmicity. Finally, we report that glial expression is sufficient for some behavioral rhythmicity to be manifest. However, the rhythmicities of animals for which per expression was confined to glia were weak, suggesting that neuronal per expression as well may be required for normal pacemaker function.

Animals↗
PubMed1992

Purification and characterization of N-acetyl-beta-D-hexosaminidase in different anatomical regions of the adult rat epididymis.

The purpose of the present study was to purify and kinetically characterize N-acetyl-beta-D-hexosaminidases A and B (EC 3.2.1.52) from the caput, corpus and caudal regions of the adult rat epididymis. The molecular mass of the purified native enzyme was approximately 250,000 and approximately 223,000 daltons for the A and B isozymes, with a subunit molecular mass of approximately 63,000 and approximately 56,000 daltons, as determined by size exclusion chromatography and gel electrophoresis under reducing conditions. The apparent Michaelis-Menten constant and maximum velocity values were 0.60, 1.55 and 0.68 mM and 0.54, 3.20 and 2.30 microM/min./mg protein for the enzyme purified from the caput, corpus and caudal regions, respectively. These values were determined by using p-nitrophenyl-N-acetyl-beta-D-glucosaminide as the substrate. These data suggest that the enzyme may be more active in the corpus region of the epididymis than in the caput and caudal regions.

Animals↗
PubMed1992

The period gene encodes a predominantly nuclear protein in adult Drosophila.

The period gene of Drosophila melanogaster (per) is important for the generation and maintenance of biological rhythms. Previous light microscopic observations indicated that per is expressed in a variety of tissues and cell types and suggested that the per protein (PER) may be present in different subcellular compartments. To understand how PER influences circadian rhythms, it is important to define its subcellular location, especially in adult flies where inducible promoter experiments suggested that it is most relevant to circadian locomotor activity rhythms. To this end, we report the results of an immunoelectron microscopic analysis of wild-type flies and per-beta-galactosidase (beta-gal) fusion gene transgenics using a polyclonal anti-PER antibody or an anti-beta-gal antibody, respectively. Most of the PER antigen and the fusion gene product were located within nuclei, suggesting that PER acts in that subcellular compartment to affect circadian rhythms. The results are discussed in terms of per's possible biochemical functions.

Animals↗
PubMed1992

The effect of an educational intervention on the use of peri-operative antimicrobial agents.

The objective of this study was to evaluate the effect of an educational intervention on the prescribing behaviour of doctors who order antimicrobial therapy for patients undergoing abdominal surgery. Two confidential criterion audits were separated by the intervention which involved completion of a 10-item questionnaire followed by a fully referenced answer sheet. The results showed a significant improvement in the prescribing habits of the junior surgical staff after the educational intervention. The overall error rate decreased from 50% to 20% (P = 0.003).

Abdomen↗
PubMed1992

The dissonance mutation at the no-on-transient-A locus of D. melanogaster: genetic control of courtship song and visual behaviors by a protein with putative RNA-binding motifs.

Genetic and molecular results are here presented revealing that the dissonance (diss) courtship song mutation is an allele of the no-on-transient-A (nonA) locus of Drosophila melanogaster. diss (now called nonAdiss) was originally isolated as a mutant with aberrant pulse song, although it was then noted to exhibit defects in responses to visual stimuli as well. The lack of transient spikes in the electroretinogram (ERG) and optomotor blindness associated with nonAdiss are shown to be similar to the visual abnormalities caused by the original nonA mutations. nonAdiss failed to complement either the ERG or optomotor defects associated with four other nonA mutations. However, all four of these nonA mutants--which were isolated on visual criteria alone--sang a normal courtship song. nonAdiss complemented at least three of the nonA mutations with regard to the singing phenotype, as assessed by a new method for temporal analysis of the male's pulse song. Both visual and song abnormalities caused by nonAdiss were rescued by P-element-mediated transformation with overlapping 11 and 16 kilobase (kb) fragments of genomic DNA (originally cloned from the nonA locus by Jones and Rubin, 1990). Analysis of behavioral phenotypes in transformed flies carrying mutagenized versions of the 11 kb genomic fragment (in a nonAdiss genomic background) localized the rescuing DNA to a region containing an open reading frame that encodes a polypeptide (NONA) with similarity to a family of RNA-binding proteins. Immunohistochemical determination of NONA's spatial and temporal expression revealed that it is localized to the nuclei of cells in many neural and non-neural tissues, at all stages of the life cycle after very early in development. Genetic connections between the control of two quite different behaviors--reproductive and visual--are discussed, along with precedences for generally expressed gene products playing roles in specific behaviors.

Alleles↗
PubMed1991

A post-transcriptional mechanism contributes to circadian cycling of a per-beta-galactosidase fusion protein.

The period gene (per) of Drosophila melanogaster affects circadian rhythms. Circadian fluctuations in per mRNA levels are thought to contribute to circadian fluctuations in per protein levels in the heads of adult flies. To address the mechanisms underlying these oscillatory phenomena, we have analyzed RNA and protein cycling from two per-beta-galactosidase fusion genes. These studies demonstrate that 5' noncoding sequences from per are sufficient to cause the fusion mRNA levels to cycle in a wild-type (rhythmic) background. Protein cycling requires additional sequences derived from the per coding region. The data suggest that there is a per-dependent posttranscriptional mechanism that is under circadian clock control required for per protein levels to fluctuate in a rhythmic fashion.

Animals↗
PubMed1991

Incentive spirometry versus routine chest physiotherapy for prevention of pulmonary complications after abdominal surgery.

We entered 876 patients into a clinical trial aimed at preventing pulmonary complications after abdominal surgery. Patients either received conventional chest physiotherapy or were encouraged to perform maximal inspiratory manoeuvres for 5 min during each hour while awake, using an incentive spirometer. The incidence of pulmonary complications did not differ significantly between the groups: incentive spirometry 68 of 431 (15.8%, 95% CI 14.0-17.6%), and chest physiotherapy 68 of 445 (15.3%, CI 13.6-17.0%). Nor was there a difference between the groups in the incidence of positive clinical signs, pyrexia, abnormal chest radiographs, pathogens in sputum, respiratory failure (PO2 less than 60 mm Hg), or length of stay in hospital. We conclude that prophylactic incentive spirometry and chest physiotherapy are of equivalent clinical efficacy in the general management of patients undergoing abdominal surgery.

Abdomen↗
PubMed1991

Molecular transfer of a species-specific behavior from Drosophila simulans to Drosophila melanogaster.

Drosophila males modulate the interpulse intervals produced during their courtship songs. These song cycles, which are altered by mutations in the clock gene period, exhibit a species-specific variation that facilitates mating. We have used chimeric period gene constructs from Drosophila melanogaster and Drosophila simulans in germline transformation experiments to map the genetic control of their song rhythm difference to a small segment of the amino acid encoding information within this gene.

Amino Acid Sequence↗
PubMed1991

A comparison of the roles of cefamandole and ceftriaxone in abdominal surgery.

In a prospective, randomized study, we compared the ability of ceftriaxone sodium (serum half-life, 8.0 hours) and cefamandole naftate and sodium carbonate (serum half-life, 0.8 hours) to prevent wound infection in 1238 patients undergoing abdominal surgery. Prophylaxis consisted of single-dose therapy at the time of induction of anesthesia, and treatment regimens contained ceftriaxone sodium, 1 g/d intravenously, or cefamandole naftate and sodium carbonate, 1 g intravenously every 6 hours. Except for low-risk biliary procedures, cephalosporin therapy was accompanied by the administration of metronidazole. No significant difference was noted in the incidence of wound infection, ie, 5.6% for the ceftriaxone group (95% confidence interval, 3.8% to 7.4%) and 6.9% for the cefamandole group (95% confidence interval, 4.9% to 8.9%). Single-dose prophylaxis with 1 g of cefamandole naftate and sodium carbonate was relatively inexpensive and provided a cost savings of 64%. When treatment was required, a 23% cost savings was associated with the use of a once-daily dose of 1 g of ceftriaxone sodium.

Abdomen↗
PubMed1991

The strength and periodicity of D. melanogaster circadian rhythms are differentially affected by alterations in period gene expression.

The per gene of D. melanogaster influences or participates in the generation of biological rhythms. Previous experiments have identified the head as the location from which per exerts its effect on circadian rhythms. To localize further this region and to examine the effects of altered levels and altered spatial expression patterns of the per gene on circadian rhythms of locomotor activity, we have characterized transformed lines containing per gene constructs missing substantial cis-acting regulatory information. The data suggest that wild-type levels of per gene expression are necessary in only a small fraction of the nervous system for near wild-type periods, whereas a larger fraction of per-expressing cells in the brain contributes to the strength of the circadian rhythms.

Animals↗