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Biomedical subjects

J C Hall

Publications and source records attributed to J C Hall.

At least 217 records · Page 12Linked to original sources
PubMed1990

Requirement for period gene expression in the adult and not during development for locomotor activity rhythms of imaginal Drosophila melanogaster.

Mutations at the period (per) locus of Drosophila melanogaster disrupt the circadian rhythm of adult locomotor activity. Molecular studies have shown that this gene is expressed primarily at the embryonic, pupal and adult stages. We have used conditional per mutants to infer the stages of development during which per expression is required for adult rhythmicity. In experiments carried out with germline transformants in which the arrhythmic per01 allele has been transformed with a heat-shock protein 70 promoter-driven per gene (hsp-per transformants) we find that per expression in the adult is both necessary and sufficient for imaginal rhythms. Results obtained with existing per alleles and other per transformant strains that behave as conditional per mutants are consistent with those obtained with these molecularly engineered conditional mutants. Using hsp-per transformants we have found that the per gene product is apparently required only at the time of manifestation of rhythmicity, and can rescue the host's arrhythmic phenotype even when supplied many days after transfer to constant darkness. We present evidence suggesting that it is necessary for pacemaker function itself, rather than being involved in a process that couples the activity of the pacemaker to the output pathway. The levels of per transcript and the abundance and tissue distribution of its protein product observed in hsp-per transformants exposed to different temperature regimes are described. An initial report of some of these results has been published previously (Ewer et al., 1988).

Activity Cycles↗
PubMed1990

Circadian fluctuations of period protein immunoreactivity in the CNS and the visual system of Drosophila.

When the protein encoded by the period (per) gene, which influences circadian rhythms in Drosophila melanogaster, was labeled with an anti-per antibody in adult flies sectioned at different times of day, regular fluctuations in the intensity of immunoreactivity were observed in cells of the visual system and central brain. These fluctuations persisted in constant darkness. Time courses of the changing levels of staining were altered in the per-short mutant: in light/dark cycles, the phase was earlier than in wild-type, and in constant darkness the period was shorter. In a per-long mutant and in behaviorally subnormal germline transformants (involving transduced per DNA), staining intensities were much fainter than in wild-type. Factors involved in initiating or maintaining the per protein cycling were investigated by examining the immunoreactivity in visual system mutants and by exposing wild-type flies to altered light/dark regimes. These genetic and environmental manipulations affected the expression of the per protein in ways that usually parallelled their effects on circadian behaviors.

Animals↗
PubMed1989

Unusual DNA structures at the integration site of an HIV provirus.

Supercoiled pHXBc2 DNA (containing the genome of the human immunodeficiency virus type 1 and human sequences) migrated more slowly than linear DNA in native and ethidium bromide agarose gel electrophoresis at 4.5 volts/cm, suggesting the presence of unusual DNA structures. S1 nuclease analysis of pHXBc2 revealed two S1 hypersensitive sites. Site I was located within a 25 bp direct repeat in host DNA 0.6 kB upstream from the 5' LTR. Site II was mapped 0.2 kB upstream from the vif gene start site. Sequence analysis showed that Site I sequences could assume different unusual DNA structures, whereas sequences at Site II could assume either slipped or H-DNA forms. Unusual DNA structures in host DNA may be associated with active chromatin regions and may favor proviral integration.

Base Sequence↗
PubMed1989

Single-dose antibiotic prophylaxis in contaminated abdominal surgery.

Although perioperative antibiotic cover reduces the incidence of septic complications associated with abdominal surgery, the optimum duration of antibiotic exposure is open to question. This clinical trial compared the efficacy of a single dose of moxalactam (1 g intravenously) with an extended course of moxalactam (1 g intravenously for eight doses) in 1027 patients undergoing contaminated abdominal surgery. The wound infection rate was 5.4% (28/519) for the single-dose schedule and 6.1% (31/508) for the extended-cover regimen (the respective 95% confidence intervals being 3.6% to 7.7% and 4.2% to 8.6%). Over 80% of all patients undergoing abdominal surgery during the period of study were entered into the trial. There was no significant difference in the incidence of other complications between the two groups under study. It is concluded that a single dose of moxalactam is as effective as a 48-hour course when attempting to prevent infection after contaminated abdominal surgery.

Biliary Tract Surgical Procedures↗
PubMed1989

Spectral analysis of courtship songs in behavioral mutants of Drosophila melanogaster.

Spectral analyses were applied to the courtship songs of the mutants cacophony (cac), dissonance (diss), fruitless (fru), and period (per), as well as to the double mutant cac diss. Aberrant intervals between song pulses were observed in diss, cac, cac diss, and fru songs. diss males displayed a defect in song hums manifested by an irregular sine wave, although the fundamental frequencies were normal. Sine song frequencies and intrapulse frequencies were aberrant in cac diss males. Two per mutant alleles (pero1 and pers) were associated with normal song [corrected] pulses and hums. These findings are discussed with regard to the mechanisms of song production and the role of these sounds in Drosophila reproduction.

Animals↗
PubMed1989

High-resolution analysis of locomotor activity rhythms in disconnected, a visual-system mutant of Drosophila melanogaster.

Free-running locomotor activity and eclosion rhythms of Drosophila melanogaster, mutant at the disconnected (disco) locus, are substantially different from the wild-type phenotype. Initial periodogram analysis revealed little or no rhythmicity (Dushay et al., 1989). We have reanalyzed the locomotor activity data using high-resolution signal analysis (maximum-entropy spectral analysis, or MESA). These analyses, corroborated by autocorrelograms, uncovered significant residual circadian rhythmicity and strong ultradian rhythms in most of the animals tested. In this regard the disco mutants are much like flies expressing mutant alleles of the period gene, as well as wild-type flies reared throughout life in constant darkness. We hypothesize that light normally triggers the coupling of multiple ultradian oscillators into a functional circadian clock and that this process is disrupted in disco flies as a result of the neural lesion.

Animals↗
PubMed1989

An antibody to the Drosophila period protein recognizes circadian pacemaker neurons in Aplysia and Bulla.

The molecular mechanisms of the pacemakers underlying circadian rhythms are not well understood. One molecule that presumably functions in the circadian clock of Drosophila is the product of the period (per) gene, which dramatically affects biological rhythms when mutated. An antibody specific for the per protein labels putative circadian pacemaker neurons and fibers in eyes of two marine gastropods, Aplysia and Bulla. As was found for the Drosophila per protein, there is a daily rhythm in the levels of the per-like antigen in Aplysia eyes. Thus, certain molecular features of the per protein, as well as aspects of the temporal regulation of its expression, may be conserved in circadian pacemakers of widely divergent species.

Animals↗
PubMed1989

Behavior and cytogenetics of fruitless in Drosophila melanogaster: different courtship defects caused by separate, closely linked lesions.

The fruitless (fru) courtship mutant was dissected into three defects of male reproductive behavior, which were separable as to their genetic etiologies by application of existing and newly induced chromosomal aberrations. fru itself is a small inversion [In(3R) 90C; 91B] on genetic and cytological criteria. Uncovering the fru distal breakpoint with deletions usually led to males with two of the fru courtship abnormalities: no copulation attempts with females (hence, behavioral sterility) and vigorous courtship among males, including the formation of "courtship chains." However, certain genetic changes involving region 91B resulted in males who formed courtship chains but who mated with females. Uncovering the fru proximal breakpoint led to males that passively elicit inappropriately high levels of courtship. This elicitation property was separable genetically from the sterility and chain formation phenotypes and provisionally mapped to the interval 89F-90F, which includes the fru proximal breakpoint. Behavioral sterility and chaining were also observed in males expressing certain abnormal genotypes, independent of the fru inversion. These included combinations of deficiencies, each with a breakpoint in 91B, and a transposon inserted in 91B.

Animals↗
PubMed1989

Fatal cardiac arrhythmia in a patient with interstitial myocarditis related to chronic arsenic poisoning.

We have reported the case of a 42-year-old man exposed to arsenic at least three times over a ten-month period from an agricultural source. He showed classical symptoms and signs of arsenic poisoning. During chelation therapy and apparent recovery from the poisoning, he suddenly and unexpectedly died; postmortem examination revealed a myocarditis similar to that reported previously. The case demonstrates the need for electrocardiographic monitoring of all patients with arsenic poisoning, during both the initial phase of the illness and convalescence.

Adult↗
PubMed1989

Hepatic involvement in listeriosis.

We report an adult with listeriosis. Sequential liver biopsies demonstrated the resolution of associated granulomas and microabscesses after the administration of high doses of penicillin for ten days. This observation has not previously been reported.

Aged↗
PubMed1989

The disconnected visual system mutations in Drosophila melanogaster drastically disrupt circadian rhythms.

Mutations at the disconnected (disco) locus in Drosophila melanogaster cause cultures of this insect to eclose in an essentially arrhythmic manner and also nearly eliminate free-running circadian rhythms of locomotor activity. Yet disco mutants are not totally light-insensitive: Whereas they performed very poorly in tests of certain behavioral responses to visual stimuli, they were able to exhibit "forced" periodic locomotor activity under conditions of light-dark cycling. We discuss these results in the context of (1) the dispensability of this insect's external photoreceptors for entrainment of its circadian pacemaker, and (2) possible disco-induced abnormalities in the connections of extraocular photoreceptors to their targets in the central nervous system and/or abnormalities in the targets themselves--which presumably include elements of the fly's circadian clock.

Animals↗
PubMed1989

Expression of a Drosophila mRNA is under circadian clock control during pupation.

Rhythmic eclosion of Drosophila adults requires per gene function. We have found that a previously identified 0.9 kb RNA transcribed from DNA adjacent to per becomes abundantly expressed during pupation, just prior to eclosion. The daily synchronized emergence of young adults, coupled with a subsequent rapid decay of the transcript, is responsible for what previously appeared to be cycling of the 0.9 kb RNA in adults. In situ hybridization analyses localize the 0.9 kb transcript to the epidermis of newly eclosed adults. Conceptual translation of genomic DNA and cDNA sequences predicts that the 0.9 kb transcript produces a 261 amino acid protein containing a putative signal sequence for membrane transport at its amino terminus. Pupae that reach the same stage of development at slightly different times of day show a subsequent synchronized rise in 0.9 kb RNA levels, indicating that the expression of this transcript is under circadian clock control.

Amino Acid Sequence↗
PubMed1989

A new mutation at the period locus of Drosophila melanogaster with some novel effects on circadian rhythms.

A new period mutation has been induced and characterized in D. melanogaster. It causes flies to be apparently arrhythmic in tests of locomotor activity and thus is superficially similar to the original per01 mutant. Yet, the new "zero" allele, per04, has some novel properties and effects: Behaviorally, per04 adults often exhibit weak, long-period rhythms of locomotor activity in constant darkness; this low-frequency rhythmicity usually was not obvious in the analog behavioral records but was readily revealed by spectral analyses. These treatments of the data also extracted hidden high-frequency (ultradian) rhythms in many of the behavioral records, of the type associated with per01 and other per-nulls. The wide range of periodicities exhibited by different per04-expressing flies implies the expression of multiple oscillatory modes by this mutant. The new mutation also leads to a tendency for flies to be hyperactive during activity monitoring and is thus dissimilar to the other arrhythmic variants in the per gene but similar to the effects of a deletion of the locus. During light:dark cycling, per04 adults once more behave differently from other per0's and in fact tend to resemble wild-type flies in these conditions. The new mutation is not caused by the same nucleotide substitution that created a stop codon in the original arrhythmic per mutant and, as it turns out, per02 and per03 as well. per04 is also not a null variant at the transcriptional level; but it leads to an anomalous form of per mRNA, which is smaller than the normal 4.5 kb species encoded by this clock gene.

Alleles↗
PubMed1989

Norwegian scabies in a patient with acquired immune deficiency syndrome.

A rare, severe form of scabies called Norwegian or keratotic scabies is described in a patient with acquired immune deficiency syndrome (AIDS). This is the first known description of this disease in an AIDS patient. The occurrence of secondary staphylococcal sepsis illustrates the importance of early correct diagnosis and treatment. Cutaneous hydration followed by aggressive application of gamma benzene hexachloride was safe and effective.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Use of peri-operative antibiotics in abdominal surgery: a criterion audit.

OBJECTIVE: To evaluate the peri-operative use of parenteral antibiotics in 100 patients undergoing abdominal surgery. METHOD: Prospective criterion audit. RESULTS: There is a need for the close monitoring of antibiotic usage within hospitals, because 39% of the patients received inappropriate antibiotic therapy.

Abdomen↗
PubMed1989

Usage of statistics in the surgical literature and the 'orphan P' phenomenon.

The statistics used in 240 surgical publications were reviewed. Basic parametric statistics were used in 60% of the publications; 21% of publications failed to document a measure of central tendency, 11% of publications contained an undefined '+/-' notation, and 10% of publications did not state the type of evaluative statistic that was used to calculate a P value, that is, an 'orphan P'. These results indicate the need for wider education about the use of descriptive and basic parametric statistics. It is impossible to evaluate the surgical literature critically without these skills.

Australia↗
PubMed1988

Interspecific comparison of the period gene of Drosophila reveals large blocks of non-conserved coding DNA.

We have cloned and sequenced the coding region of the period (per) gene from Drosophila pseudoobscura and D. virilis. A comparison with that of D. melanogaster reveals that the conceptual translation products consist of interspersed blocks of conserved and non-conserved amino acid sequence. The non-conserved portion, comprising approximately 33% of the protein sequence, includes the perfect Thr-Gly repeat of D. melanogaster, which is absent from the D. pseudoobscura and D. virilis proteins. Based on these observations and cross-species transformation experiments, we suggest that the interspecific variability in the per primary amino acid sequence contributes to the control of species-specific behaviors.

Amino Acid Sequence↗