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Biomedical subjects

J C Hall

Publications and source records attributed to J C Hall.

At least 145 records · Page 8Linked to original sources
PubMed1996

Mosaic analysis in the Drosophila CNS of circadian and courtship-song rhythms affected by a period clock mutation.

The period gene in Drosophila melanogaster controls not only daily rhythms associated with adult emergence and behavior, but also a much higher frequency rhythm that accompanies the male's courtship song. This oscillation in the rate of sound production (normal period, ca. one minute) is either sped up (by perS), slowed down, or eliminated in the three classic per mutants. We have conducted a mosaic analysis in which both lovesong and circadian locomotor cycles were examined in a series of flies that were each part perS and part per+. Consistent with previous studies, the focus for per control of the adult's circadian rhythm of locomotion was found to be in the brain. However, several mosaic individuals were found to exhibit a mutant locomotor rhythm but a wild-type song cycle, or vice-versa, enabling us provisionally to map the song-rhythm focus to the thoracic ganglia. That per is expressed only in glial cells in the thoracic nervous system and, in general, mediates slow (hour-by-hour) fluctuations in the levels of its own products are discussed from the standpoint of the current mosaic mapping results and the renewed focus they bring to the gene's influence on an ultradian rhythm.

Animals↗
PubMed1996

The quality of life of patients on a waiting list for transurethral resection of the prostate.

We evaluated the quality of life of 50 patients with benign prostatic hypertrophy on a waiting list for transurethral resection of the prostate. The patients had a median age of 68 years (range: 48-84 years) and had been on the waiting list for a median of eight months (range: 2-36 months). Patients were assessed using the Benign Prostatic Hypertrophy Health-Related Quality of Life Survey Questionnaire. All patients had disagreeable urinary symptoms that interfered with their normal activities, for example, 92% of patients were troubled by disturbed sleep. The patients also had worries about the possibility of prostatic cancer (40%) and a perceived deterioration in sexual performance during the preceding year (56%). Eleven of the 14 patients who were re-evaluated one year after a transurethral resection of the prostate were completely free of any bothersome urinary symptoms.

Aged↗
PubMed1996

ASA status and age predict adverse events after abdominal surgery.

The objective of this study was to evaluate the ability of age and the American Society of Anesthesiologists (ASA) score to act as clinical indicators and predict clinical adversity after abdominal surgery. We evaluated 2570 patients who underwent abdominal surgery. The data were collected in a prospective manner with an unbiased measurement of the baseline risk and endpoint criteria. Age > 60 years and/or an ASA score > 2 identified over 80% of the patients who had a prolonged stay in hospital, developed intraperitoneal sepsis, were admitted to the ICU or died. This effect was additive which implies a useful degree of independence between the two risk factors. Age and the ASA score are useful indicators of clinical adversity and resource utilization after abdominal surgery. Hence, they can be used to benchmark the outcome of abdominal surgery between institutions.

Abdomen↗
PubMed1995

Comparison of flash-induced light-scattering transients and proton efflux from auxinic-herbicide resistant and susceptible wild mustard protoplasts: a possible role for calcium in mediating auxinic herbicide resistance.

Comparison of flash-induced light-scattering signals from protoplasts of auxinic herbicide-resistant ('R') and -susceptible ('S') wild mustard biotypes suggest that ATP-dependent activity manifested as a conformational change differs between the biotypes. The signal obtained from R protoplasts is unaffected by 50 microM picloram, an auxin analogue. In comparison, the signal amplitude from the S protoplasts decreases 40% in 20 microM picloram and is abolished in 50 microM picloram. Signal amplitude from the R protoplasts can be decreased by simultaneous incubation with 50 microM picloram and 50 microM verapamil, a calcium channel blocker. Incubation of the S protoplasts with the calcium ionophore A23187 in the presence of 0.5 mM calcium reduced the inhibitory effect of picloram. Absorbance spectrophotometry using acridine orange as a pH indicator suggests that picloram affects the proton flux in the S biotype only. Based on these results, we hypothesize that picloram affects the calcium and hydrogen dynamics in the S biotype. Because the scattering characteristics of S protoplasts incubated with picloram can be nearly reproduced in the R protoplasts by simultaneous incubation with picloram and verapamil, calcium may have a significant role in modulating auxinic herbicide resistance. To our knowledge, this is the first report to implicate such a role for calcium.

Acridine Orange↗
PubMed1995

Tripping along the trail to the molecular mechanisms of biological clocks.

Solving the mechanism of circadian clocks has become an important goal, in part because daily rhythms are running in such a wide variety of organisms, and contribute to many aspects of their well being. Systematic genetic approaches to studying 'the clock' were initiated in fruitflies more than 20 years ago as a novel means by which neural-pacemaking mysteries might be solved. Such chronogenetic investigations gained momentum when they spread to other species, and became molecular. However, the molecular studies were misleading, that is, until some elementary neuro-anatomical observations, involving the expression of a 'clock gene' in Drosophila, gave the experiments in this molecular-neurogenetic area of chronobiology a new direction. The initially neuro-descriptive studies led to the current investigations that involve negatively acting transcription factors and other clock molecules that are presumed to interact with them. In addition, new mutants and clones have been isolated in a timely manner. These mutations and molecules should permit chronogeneticists, working on a wide variety of organisms, to unravel further details of how the clock works, how environmental information finds its way to it, and how it sends information out into the organism's physiology, biochemistry and behavior.

Animals↗
PubMed1995

Continuous quality improvement in a day ward.

The increasing usage of short-stay facilities within Australia has focused attention upon the efficiency of surgical day wards. Although the Australian Council on Healthcare Standards (ACHS) is actively promoting the development of clinical indicators for same-day facilities, there is a concern that these measurements relate to efficiency rather than to humanitarian aspects of the quality of service. We have established a programme of continuous quality improvement (CQI) in a surgical day ward with the nursing and clerical staff being empowered as core members of the team. Reviews and audits have identified a number of targets for our activity. Some issues have been resolved very easily (ward clerks telephoning patients to confirm admissions the next day) but the solution to some other problems has required lengthy negotiations between various groups (the construction of clearly written pre-admission guidelines for patients). Activities aimed at improving the service provided to patients attending surgical day wards must extend beyond the mere collection of information about clinical indicators.

Ambulatory Surgical Procedures↗
PubMed1994

Acetylcholinesterase staining in the auditory brainstem nuclei of the leopard frog, Rana pipiens.

We examined the distribution of acetycholinesterase (AChE) in the brainstem auditory nuclei of leopard frogs (Rana pipiens). Numerous AChE-labeled somata were observed in caudal brainstem nuclei including the dorsolateral nucleus, superior olivary nucleus, and superficial reticular nucleus. At midbrain levels, AChE-labeled somata were observed in the magnocellular, principal and laminar nuclei of the torus semicircularis, though, most were located in the magnocellular nucleus. Neuropil labeling, while present throughout the auditory brainstem, was particularly pronounced in the principal nucleus of the torus. These findings suggest that the auditory system of anurans, like that of birds and mammals, comprises, in part, distinct cholinergic pathways.

Acetylcholine↗
PubMed1994

The mating of a fly.

Courtship in Drosophila is influenced by a wide variety of genes, in that many different kinds of pleiotropic mutations lead to defective courtship. This may seem to be a truism, but the broad temporal and spatial expression of most of the fly's "neuro genes" makes it difficult to exclude elements of such genes' actions as materially underlying reproductive behavior. "Courtship genes" that seem to play more particular roles were originally identified as sensory, learning, or rhythm mutations; their reproductive abnormalities have been especially informative for revealing components of male or female actions that might otherwise have gone unnoticed. Further behavioral mutations seemed originally to be courtship-specific, turned out not to have that property, and have led to a broadened perspective on the nature and action of Drosophila's sex-determination genes.

Animals↗
PubMed1994

Behavioral and neurobiological implications of sex-determining factors in Drosophila.

The function of the central nervous system as it controls sex-specific behaviors in Drosophila has been studied with renewed intensity, in the context of genetic factors that influence the development of sexually differentiated aspects of this insect. Three categories of genetic variations that cause anomalies in courtship and mating behaviors are discussed: (1) mutants isolated with regard to courtship defects, of which putatively courtship-specific variants such as the fruitless mutant are a subset; (2) general behavioral and neurological variants (including sensory and learning mutants), whose defects include subnormal reproductive performance; and (3) mutations of genes within the sex-determination regulatory hierarchy of Drosophila, the analysis of which has included studies of reproductive behavior. Recent studies of mutations in two of these categories have provided new insights into the control of neuronally based aspects of sex-specific behavior. The doublesex gene, the final factor acting in the sex-determination hierarchy, had been previously thought to regulate all aspects of sexual differentiation. Yet, it has been recently shown that doublesex does not control at least one neuronally-determined feature of sex-specific anatomy--a muscle in the male's abdomen, whose normal development is, however, dependent on the action of fruitless. These considerations prompted us to examine further (and in some cases re-examine) the influences exerted by sex-determination hierarchy genes on behavior. Our results--notably those obtained from assessments of doublesex mutations' effects on general reproductive actions and on a particular component of the courtship sequence (male "singing" behavior)--lead to the suggestion that there is a previously unrecognized branch within the sex-determination hierarchy, which controls the differentiation of the male- and female- specific phenotypes of Drosophila. This new branch separates from the doublesex-related one immediately before the action of that gene (just after transformer and transformer-2) and appears to control as least some aspects of neuronally determined sexual differentiation of males.

Animals↗
PubMed1994

A promoterless period gene mediates behavioral rhythmicity and cyclical per expression in a restricted subset of the Drosophila nervous system.

Transgenic flies carrying a 7.2 kb piece of DNA from the period (per) gene were analyzed for the presence of circadian locomotor activity rhythms and fluctuations of per-encoded mRNA and protein. The 5' end of this genomic fragment is within the first intron, which precedes the coding region. This promotorless fragment could rescue circadian behavioral rhythms and mediate spatial expression of PER in a subset of wild-type per cells within the CNS and PNS. In one behaviorally rhythmic line, PER protein was found in only "per lateral neurons." In the rhythmic transgenics, per mRNA and protein levels undergo circadian cycling, as previously described for wild type. Cycling of PER in brain cells of flies carrying the same 7.2 kb piece of per DNA under the control of a heat shock promoter corroborated the hypothesis that per's molecular cyclings and behavioral rhythmicity are causally related.

Animals↗
PubMed1994

Dosage compensation of the period gene in Drosophila melanogaster.

The period (per) gene is located on the X chromosome of Drosophila melanogaster. Its expression influences biological clocks in this fruit fly, including the one that subserves circadian rhythms of locomotor activity. Like most X-linked genes in Drosophila, per is under the regulatory control of gene dosage compensation. In this study, we assessed the activity of altered or augmented per+ DNA fragments in transformants. Relative expression levels in male and female adults were inferred from periodicities associated with locomotor behavioral rhythms, and by histochemically assessing beta-galactosidase levels in transgenics carrying different kinds of per-lacZ fusion genes. The results suggest that per contains multipartite regulatory information for dosage compensation within the large first intron and also within the 3' half of this genetic locus.

Animals↗
PubMed1994

Australian National Diagnosis Related Groups and Abdominal surgery.

This study compares the declared splits for abdominal surgery within the Australian National Diagnosis Related Groups (AN-DRG) with age-based strata. Data were derived from two clinical trials involving 2114 adults. The patients tended to be elderly (25% > 71 years) and had significant co-morbidity, that is, 57% with an American Society of Anesthesia (ASA) classification > 1. Adverse events after surgery included pulmonary complications (16%), urinary tract infections (10%), wound infection (6%), and death (4.5%). Only 27% of the patients could be classified into a 'non-complicated' AN-DRG partition; these patients had a median age of 25 years and 88% had either appendicectomy or cholecystectomy. In contrast, analysis of six age-based strata revealed a stepwise increase in the incidence of adverse events after surgery (Friedman ANOVA, P < 0.001). It might therefore be wise to consider the inclusion of age-strata in the abdominal surgery component of the AN-DRG. Failure to do so may result in financial penalties for hospitals that care for patients at high risk of an adverse outcome after abdominal surgery.

Abdomen↗
PubMed1994

Spindle cell hemangioendothelioma. Report of three cases and review of the literature.

BACKGROUND: Spindle cell hemangioendothelioma lesions are uncommon, affect a wide age range in both sexes, and show a predilection for skin and subcutaneous tissue of the extremities. OBJECTIVE: To present three cases of spindle cell hemangioendothelioma and review the literature. METHODS: Three cases of spindle cell hemangioendothelioma are presented. RESULTS: Two of our cases first presented very early in life and progressed by local recurrences over many years. None of our cases showed evidence of metastases, but the lesions exhibited local aggressive and invasive behavior. Histologically, the lesions consist of alternating areas of dilated, thin walled cavernous vascular spaces and solid areas composed predominantly of spindle cells and clusters of epithelioid endothelial cells with intracytoplasmic vacuoles. That spindle cell hemangioendothelioma is a non-neoplastic lesion and not a neoplasm of borderline malignancy is suggested by the following observations from our cases: the repeated presence of organized intravascular thrombi in all cases, the early clinical presentation in two cases, and the presence of some degree of vascular malformation at the periphery of lesions. CONCLUSION: Both clinicians and pathologists should be aware of the existence of this lesion in order to diagnose and treat an affected patient correctly.

Adult↗