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J C Hall

Publications and source records attributed to J C Hall.

At least 235 records · Page 13Linked to original sources
PubMed1988

The period gene of Drosophila carries species-specific behavioral instructions.

We have analyzed and compared the circadian locomotor activity rhythms of Drosophila melanogaster and D.pseudoobscura. The rhythms of D.pseudoobscura are stronger and the periods shorter than those of D.melanogaster. We have also transformed D.melanogaster flies with a hybrid gene containing the coding region of the D.pseudoobscura period (per) gene. Behavioral assays of flies containing this hybrid gene show that the per protein encoded by the D.pseudoobscura per gene is able to rescue the rhythmic deficiencies of arrhythmic, pero1 D.melanogaster. More important, the rhythms of some of these strains are stronger and the periods shorter than those of D.melanogaster (and those of transformants which carry the equivalent D.melanogaster per gene construct) and hence resemble those of D.pseudoobscura. The results suggest that the primary amino acid sequence of the per gene encodes species-specific behavioral instructions that are detectable when only the per gene is transferred to a different species.

Animals↗
PubMed1988

Slipped DNA structures within the enhancer region of the Moloney murine leukemia virus.

We have examined the S1 nuclease sensitivity of supercoiled plasmids harboring the Moloney Murine Leukemia Virus (MoMuLV) long terminal repeat (LTR). S1 sensitivity was found within the LTR enhancer direct repeats. Transformation of E. coli DH5 cells with a construct containing most of the MoMuLV LTR yielded the precise deletion of one direct repeat and loss of S1 sensitivity. The dependence of S1 sensitivity on the presence of both direct repeats, together with the exact excision of one direct repeat by E. coli, suggests the presence of slipped DNA within the enhancer. Such structures may represent targets for effector proteins which mediate vital functions during viral propagation.

Base Sequence↗
PubMed1988

An inducible promoter fused to the period gene in Drosophila conditionally rescues adult per-mutant arrhythmicity.

The period (per) gene of Drosophila melanogaster is involved in the expression of circadian rhythms of locomotor activity in adult flies. Molecular studies of per (reviewed in ref. 2) have shown that the transcribed and translated products of this gene are present primarily at the embryonic, pupal and adult stages. Here we describe experiments with arrhythmic per mutants bearing an inducible form of this gene which indicate that strongly rhythmic adult behaviour can be obtained only if per expression is induced in the adult, independent of its history of expression earlier in development. Thus per-mutant locomotor-activity phenotypes seem not to result from abnormalities in the development of neural structures or in physiological processes that may be required at pre-adult stages for the expression of this circadian rhythm. Moreover, the action of per after light:dark cycle entrainment seems to be sufficient for activity rhythms to be exhibited in constant darkness; this suggests further that the per product is required only during the time that the rhythmic behaviour is being manifested. Our strategy used a heat-shock gene promotor fused to per coding sequences to obtain conditional gene expression. Heat-shock promoter-driven genes have previously been used to study the mode of action and tissue specificity of a variety of Drosophila genes; our experiments on circadian rhythms demonstrate the use of such gene constructions for the temporal manipulation of genes whose phenotypes, behavioural and otherwise, affect whole organisms.

Animals↗
PubMed1988

Epoprostenol (PGI2, prostacyclin) during high-risk hemodialysis: preventing further bleeding complications.

The frequency of hemodialysis-associated hemorrhage was studied prospectively in two successive, parallel, heparin-controlled studies using epoprostenol (PGI2; average dose, 4.1 ng/kg.min) as the sole antithrombotic agent. Sixty-three patients with active or recently active bleeding underwent 163 hemodialysis treatments in each of which prospective bleeding risk was assessed. PGI2 was associated with up to 50% overall reduction in the frequency of bleeding, particularly in the highest risk circumstances. PGI2 also allowed successful completion of the full, prospectively prescribed hemodialysis time in the most treatments (82% versus 93% with heparin). Furthermore, the efficiency of hemodialysis using PGI2, as indicated by the reduction in concentration of blood urea nitrogen and serum creatinine, was equal to that using heparin, even though there was a tendency toward modest reduction in residual volume of the hollow fiber dialyzer and slightly more frequent early termination of treatment from dialyzer clotting with PGI2. No severe vasodilatory side effects of PGI2 were observed during these studies. Hypotension was equally frequent during hemodialysis with heparin as with PGI2. The current results suggest that PGI2 should be considered as a substitute for heparin during high-risk hemodialysis because PGI2 may reduce the incidence of dialysis-associated bleeding without severe adverse side effects.

Adolescent↗
PubMed1988

Schistosomatium douthitti: biochemical and morphological effects of an experimental infection in mice.

The pathophysiological changes that occur in mice experimentally infected with Schistosomatium douthitti were studied. Male ICR mice, 6-8 weeks in age, were exposed to 100 cercariae of S. douthitti from infected snails (Lymnaea catascopium) and sacrificed weekly for a total of 13 weeks. Liver homogenates, serum samples, and histological sections of liver tissue were examined. Results showed that body weights of animals with prepatent infections were higher than those of corresponding controls. After patency, which occurred at 5 weeks, body weights were lower and liver weights were higher resulting in significantly increased liver weight/body weight ratios. Hematocrit values declined progressively in patent infections. Total cholesterol in liver was generally higher in the parasitized groups reaching significance during patency. Values rose with age in both control and parasitized groups, but sooner in the latter. Free cholesterol was increased in the liver of animals with patent infections. Total lipid content of the liver was reduced in the infected animals throughout the study. Both liver glycogen and serum glucose levels in the infected animals rose over the control values. The activity of alkaline phosphatase (E.C.3.1.3.1) was elevated in liver tissue of infected mice. Glutamic-pyruvic transaminase (E.C.2.6.1.2) activity was higher in serum but lower in the livers of animals harboring patent infections. Total bile salt concentration in parasitized animals did not differ appreciably from control values; however, gallbladders were enlarged five times in the infected animals. Histologically, liver sections from infected mice showed granulomas in various stages of formation and degeneration. Granulomas contained from 1 to 40 schistosome eggs. After 6 weeks of infection, granulomas were characterized by many neutrophils and monocytes. Few lymphocytes and eosinophils were present. As the granulomas developed, fibroblasts and connective tissue became more prominent. Glycogen deposits were observed surrounding granulomas and were increased in older infections. Adult worms contained abundant amounts of glycogen and cholesterol in their parenchymal tissues.

Alanine Transaminase↗
PubMed1988

Influence of envelope rise time on neural responses in the auditory system of anurans.

The influence of envelope rise time on neural responses was investigated in the central auditory pathway of frogs. Single unit and evoked potential recordings were made from the dorsal medullary nucleus (DMN) and thalamus, respectively. It was found that phasic neurons (15% of the population) in the DMN responded preferentially to stimuli with rapid (less than 25 ms) rise times. Acoustically evoked potentials (AEPs) recorded from the thalamus, specifically the Nucleus of Bellonci, also showed more pronounced responses to stimuli with rapid, rather than slower, envelope rise times. Interestingly, the leopard frog mating call, which has a rapid onset, elicited strong neuronal discharge both within the DMN and thalamus. In contrast, the mating call of bullfrogs, a species sympatric with leopard frogs, has a characteristically slow (greater than 100 ms) envelope rise time and elicited little, if any, response. These findings indicate the presence of neural specializations within the frog's auditory pathway for the optimal detection of the conspecific mating call. The relevance of these findings for stimulus coding in the auditory pathway of other vertebrates is discussed.

Animals↗
PubMed1988

Antibodies to the period gene product of Drosophila reveal diverse tissue distribution and rhythmic changes in the visual system.

Polyclonal antibodies were prepared against the period gene product, which influences biological rhythms in D. melanogaster, by using small synthetic peptides from the per sequence as immunogens. The peptide that elicited the best antibody reagent was a small domain near the site of the pers (short period) mutation. Specific immunohistochemical staining was detected in a variety of tissue types: the embryonic CNS; a few cell bodies in the central brain of pupae; these and other cells in the central brain of adults, as well as imaginal cells in the eyes, optic lobes, and the gut. The intensity of per-specific staining in the visual system was found to oscillate, defining a free-running circadian rhythm with a peak in the middle of the night.

Animals↗
PubMed1988

The dissonance mutant of courtship song in Drosophila melanogaster: isolation, behavior and cytogenetics.

The dissonance mutant of courtship song was induced by chemical mutagenesis. This X-chromosomal mutation causes the D. melanogaster male's acoustical output, resulting from his wing vibrations directed at a female, to include very long and loud tone "pulses." Yet, a given train of pulses starts out as normal, with the signals in all but the shortest singing bouts eventually becoming polycyclic and high-amplitude. The aberrant songs caused by diss (map position, 1-52; cytological interval, 14C1-2 to 14C4-5) were quantitatively compared to those produced by mutant cacophony males, whose pulses are much more uniformly polycyclic (due to a mutation mapping elsewhere on the X chromosome). Males or females expressing diss are normal in several "general" behaviors. Yet diss males not only sing abnormally, but they also exhibit longer-than-normal mating latencies in their courtship of females. These decrements seem to be associated, at least in part, with visually aberrant behavior of diss flies--measured with regard to male courtship per se, and also in tests of more general visual responses. Such defects were found when testing diss males or females, and the genetic etiology of the visual impairments were provisionally mapped to the same locus to which the song abnormality has been localized. Neurogenetic connections between the control of courtship singing behavior and visual system functions are discussed with respect to the new song mutation (diss) and the older one (cac)--which also turned out to be genetically related to a mutation that causes abnormalities of light-induced behavior and physiology.

Animals↗
PubMed1988

Spatial and temporal expression of the period gene in Drosophila melanogaster.

The temporal and spatial expression of the period gene of Drosophila melanogaster has been analyzed by examining the expression of a per beta-galactosidase fusion gene in transformants and by in situ hybridization experiments with wild-type flies. Several strains of Drosophila melanogaster, transformed with the fusion gene, have been generated. The gene is active in mid-late embryos in the midline of the nervous system. Thereafter, beta-galactosidase activity is undetectable until the pupal stage when the prothoracic gland-corpora allata and the optic lobes are beta-galactosidase positive. In adults a surprisingly large number of tissues stain positively, including antennae, proboscis, eyes, optic lobes, cells of the central brain, cells of the thoracic ganglia, gut, Malpighian tubules, and ovarian follicle cells. The temporal pattern of expression agrees well with previous estimates made from developmental Northern blots with RNA extracted from wild-type animals. We suggest that many of the tissues that express the per gene contain their own intrinsic oscillator activity.

Animals↗
PubMed1988

Cost-efficiency of a long-acting cephalosporin agent.

In a prospective longitudinal study of patients in a general surgical ward, the relative cost-efficiencies of a long-acting third generation cephalosporin (ceftriaxone--mean plasma elimination t 1/2 390 min) and a short-acting second generation cephalosporin (cephamandole: mean plasma elimination t 1/2 32 min) were determined. The total cost of therapy for 24 h was +32.88 for cephamandole and +22.78 for ceftriaxone, that is, a reduction of 31%. Considerable cost containment can be achieved by using third generation cephalosporin agents that only require the administration of one intravenous injection per day.

Abdomen↗
PubMed1988

Cutaneous mucormycosis in a heart transplant patient.

We present the first case of cutaneous mucormycosis reported in a patient who had undergone a heart transplant operation. This appeared to be a localized infection without a predisposing local factor such as a surgical adhesive and without evidence of dissemination. Prompt treatment with intravenous amphotericin B resulted in an apparent cure.

Adult↗
PubMed1988

Heparin-induced cutaneous necrosis in a postpartum patient.

A case of heparin-induced cutaneous necrosis resembling necrotizing fasciitis occurred in a post-cesarean section patient. She presented with massive necrosis of the skin and abdominal pannus on the sixth postoperative day after a cesarean section for severe preeclampsia and failed induction. A biopsy showed findings characteristic of heparin-induced cutaneous necrosis, permitting conservative therapy.

Adult↗
PubMed1988

Lesions of the mesolimbic dopamine system disrupt signalled escape responses in the rat.

Classically conditioned shuttling and escape responses of 14 rats with 6-hydroxydopamine lesions of the ventral tegmental area (VTA) were compared with those of 16 sham-lesioned control rats in an aversive classical conditioning paradigm. Although the 6-OHDA lesion did not enhance classically conditioned shuttling, it eliminated the facilitation of escape responses by the conditioned stimulus. Thus, whereas the classically conditioned sham-lesioned rats were faster to escape shock than were the pseudoconditioned sham-lesioned rats, the 6-OHDA classically conditioned and pseudoconditioned rats were equally slow to escape. This suggests that the ability of the rat to respond appropriately to the motivational or informational content of the warning signal was disrupted following damage to the mesolimbic dopamine system.

Animals↗
PubMed1988

Scalp colonization by Trichophyton tonsurans in an urban pediatric clinic. ?Asymptomatic carrier state.

Random culturing of the scalp in 200 healthy children in a large metropolitan children's hospital revealed that eight (4%) of the patients had cultures that were positive for Trichophyton tonsurans variety sulfureum. Infections were not clinically apparent and were asymptomatic. All of the patients with positive cultures were black and six braided their hair. Trichophyton tonsurans appears to exist in an asymptomatic state in this well-defined population of children.

Black People↗
PubMed1987

Evidence for parallel processing in the frog's auditory thalamus.

We have conducted anatomical and physiological experiments to investigate the functional organization of the dorsal thalamus in the northern leopard frog (Rana pipiens pipiens). Our studies provide evidence for parallel auditory processing at this level of the frog's brain. Acoustically evoked potentials were recorded from the posterior and central thalamic nuclei and several differences in sound-evoked activity were noted between them: the amplitude of acoustically evoked potentials (AEPs), in response to a standard search stimulus, was always greater in the central, as opposed to the posterior, nucleus; the posterior, but not central, nucleus exhibited the phenomenon of nonlinear summation when 350-Hz and 1,700-Hz tones were presented simultaneously rather than individually; and the central, but not posterior, nucleus showed selectivity for the repetition rate of pulsed sound signals. The posterior and central thalamic nuclei also possessed distinct innervation patterns as revealed by the HRP transport patterns arising from these structures. The central nucleus was reciprocally connected with the major auditory relay stations along the frog's central auditory pathway including the superior olive, nucleus of the lateral lemniscus, and the torus semicircularis. Major projections to the lateral thalamic nucleus, ventral hypothalamus, and the telencephalic striatal complex were also observed. The posterior nucleus, on the other hand, established reciprocal connections primarily with the medial reticular nucleus, ventral midbrain tegmentum, and structures constituting of the ventral thalamic nuclei, particularly the nucleus of Bellonci. Thus, time and frequency cues contained within the species mating call, and conveying information concerning species identity, appear to be processed independently within the frog's thalamus with separate neural channels for each.

Animals↗