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J C Hall

Publications and source records attributed to J C Hall.

At least 271 records · Page 15Linked to original sources
PubMed1986

Embryonic expression of the period clock gene in the central nervous system of Drosophila melanogaster.

We have examined the temporal and spatial expression of the 4.5-kb mRNA that is transcribed from the period locus of Drosophila melanogaster and is the best candidate for the per gene product. Both Northern blot analyses and hybridizations in situ to tissue sections reveal significant expression of the 4.5-kb mRNA in embryos. This expression is limited to the central nervous system of the developing embryo and is localized within the brain and ventral ganglia. The 4.5-kb mRNA is enriched in adult heads (by Northern blotting) although we were not able to detect specific localization (in situ). In addition to the physiological role the 4.5-kb mRNA might have in maintaining biological rhythms, we now suggest that it has a developmental role for establishing mechanisms that are necessary for eventual expression of clock functions.

Animals↗
PubMed1986

Germ-line transformation involving DNA from the period locus in Drosophila melanogaster: overlapping genomic fragments that restore circadian and ultradian rhythmicity to per0 and per- mutants.

P-element-mediated transformations involving DNA fragments from the period (per) clock gene of Drosophila melanogaster have shown that several subsegments of the locus restore rhythmicity to per0 or per- mutants. Such fragments overlap in a genomic region complementary to one transcript, a 4.5-kb RNA which is probably the per message, in that it is necessary and (in terms of expression from this X-chromosomal locus) sufficient for the fly's circadian rhythms. It is also at least necessary for the high-frequency oscillations normally produced by courting males as they vibrate their wings. The entirety of the 4.5-kb transcript is not necessary for rather strong rhythmicity; nor does it seem to be sufficient, in transformants, for wild-type behavioral phenotypes. A 0.9-kb RNA, homologous to genomic region immediately adjacent to the source of the 4.5-kb species, oscillates in its abundance over the course of a day; but coverage of this transcript source in several transformants carrying a per0 mutation--which eliminates the 0.9-kb RNA's oscillation--does not restore rhythmicity. All of the independently isolated arrhythmic mutations tested were covered by the same array of overlapping per+-derived DNA fragments, implying that the only portion of the locus which has mutated to arrhythmicity is complementary to the 4.5-kb transcript.

Animals↗
PubMed1986

Abuse-provoking characteristics of institutionalized mentally retarded individuals.

Abuse-provoking characteristics of institutionalized mentally retarded individuals were examined. A group of 80 abused retarded clients in a residential setting were compared to a group of 80 nonabused clients. The two groups were compared on IQs, social quotients, presence of physical disabilities, aggressive behavior, ability to communicate verbally, presence of self-injurious behavior, ability to ambulate, sex, and age. Six of these characteristics (social quotient, aggression, verbal ability, age, self-injurious behavior, and ambulation) were significant in differentiating the abused from nonabused retarded individuals. A discriminant function was developed to help identify those clients who may be at risk of being abused.

Adolescent↗
PubMed1985

Reduced reproductive success for a conditioning mutant in experimental populations of Drosophila melanogaster.

Male Drosophila melanogaster that have courted newly-emerged males can modify their subsequent courtship behavior to avoid further courtship with immature males for up to 6 hr (previously reported). Here, it was hypothesized that such an experience-dependent modification would afford a mating advantage to normal males over males that carried a mutation that affects learning and memory. Coisogenic lines were constructed which varied at the dunce gene (dnc+ and dncM14 alleles) in order to test this hypothesis. Whether previously experienced with immature males or not, dnc+ and dncM14 males were indistinguishable in their response and mating efficiency when individually paired with virgin females. However, courtship performance of dnc+ and dncM14 males was different if they were first experienced with immature males and were then individually tested in an artificial population of nine immature males and one virgin female. In this situation, dnc+ males spent much less time in courtship with immature males and achieved copulation in one-third the time required for dncM14 males. As a control, the behavior and mating efficiency of courtship-naive dnc+ and dncM14 males in the artificial population was indistinguishable. In competition for a single virgin female, experienced dncM14 males showed a slight mating advantage over experienced dnc+ males. But when competition by experienced males for a single virgin female took place in the presence of nine immature males, dnc+ males were the successful maters in three-fourths of the trials.

Animals↗
PubMed1985

An evaluation of the role of ethylene in herbicidal injury induced by picloram or clopyralid in rapeseed and sunflower plants.

The role of ethylene in herbicidal injury induced by 4-amino-3,5,6-trichloropicolinic acid (picloram) or 3,6-dichloropicolinic acid (clopyralid) was investigated in sunflower (Helianthus annuus L.) and rapeseed (Brassica napus L. cv Altex). Picloram induces herbicide injury in both species, whereas clopyralid induces injury only in sunflower. Picloram applied to the third leaf of a rapeseed plant increased ethylene evolution several-fold. Clopyralid had no effect on ethylene production in rapeseed. In sunflower, both picloram and clopyralid elevated ethylene production. Ethylene biosynthesis induced by the herbicide treatment was not restricted to treated areas. When clopyralid was applied only to the lower stem and cotyledons of sunflower, the herbicide treatment resulted in an increase in the rate of ethylene production from the true leaves. Increased ethylene production preceded or coincided with the onset of morphological responses induced by a herbicide application to a susceptible species. The contrast in ethylene production by these two plant species cannot be accounted for by differences in absorption and translocation of clopyralid and picloram.Treatment with aminoethoxyvinylglycine (AVG) before picloram or clopyralid application prevented an increase in ethylene production. Pretreatment with AVG also delayed the development of morphological changes induced by picloram or clopyralid. It appears that enhanced ethylene biosynthesis after application of picloram or clopyralid to the susceptible plant species was a factor involved in resulting morphological changes.

Journal Article↗
PubMed1985

Dopexamine: a novel agonist at peripheral dopamine receptors and beta 2-adrenoceptors.

Dopexamine is an agonist at peripheral dopamine receptors and at beta 2-adrenoceptors. Dopexamine has approximately one-third the potency of dopamine in stimulating the vascular DA1-receptor in the dog, resulting in a fall in renal vascular resistance of 20% at 2.3 X 10(-8) mol kg-1 (i.a.). Prejunctional DA2-receptors are also stimulated by dopexamine, resulting in a reduction of neurogenic vasoconstriction in the rabbit isolated ear artery (IC50 of 1.15 X 10(-6)M) and of neurogenic tachycardia in the cat (ID50 of 5.4 X 10(-8) mol kg-1, i.v.), with a potency six and four times less respectively than that of dopamine. By contrast, dopexamine is approximately 60 times more potent than dopamine as an agonist at the beta 2-adrenoceptor of the guinea-pig isolated tracheal chain, with an EC50 of 1.5 X 10(-6)M. Both dopexamine and dopamine are weak agonists at the guinea-pig atrial beta 1-adrenoceptor over the concentration range 10(-7) to 10(-4) M, but dopexamine has an intrinsic activity of only 0.16 relative to dopamine. Dopexamine does not stimulate postjunctional alpha 1- or alpha 2-adrenoceptors in the canine isolated saphenous vein, whereas dopamine is an agonist, approximately 120 times less potent than noradrenaline. Unlike dopamine and salbutamol, dopexamine does not cause arrhythmias in the guinea-pig isolated perfused heart at doses of up to 10(-5) mol, which is a thousand times the minimum cardiostimulant dose. The combination of agonist properties at peripheral dopamine receptors and at beta 2-adrenoceptors, with little or no activity at alpha- and beta 1-adrenoceptors gives dopexamine a novel pharmacological profile. This may confer advantages over dopamine in the treatment of acute heart failure.

Adrenergic Agonists↗
PubMed1985

The effects of dopexamine on the cardiovascular system of the dog.

The cardiovascular effects of dopexamine and dopamine were compared in the anaesthetized and conscious dog by the use of intravenous infusions over the dose range 3 X 10(-9) - 10(-7)mol kg-1 min-1. In the anaesthetized dog, dopexamine produced a dose-related fall in blood pressure due to peripheral vasodilatation and a small rise in heart rate and contractility. By contrast, dopamine did not significantly reduce blood pressure but produced a larger dose-related increase in contractility. At the highest infusion rate (10(-7)mol kg-1 min-1) blood pressure and heart rate were increased by dopamine. Dopexamine dilated the renal and mesenteric vascular beds with a potency similar to that of dopamine. Femoral vascular responses produced by both agents were inconsistent but the highest infusion rate of dopamine did produce vasoconstriction. With the aid of selective receptor antagonists (haloperidol, propranolol and bulbocapnine) the vasodepressor activity of dopexamine was shown to be mediated by stimulation of DA2-, beta- and DA1-receptors. The cardiac stimulation and renal vasodilatation produced by both compounds were due to stimulation of beta-adrenoceptors and DA1-receptors respectively. In the conscious dog, intravenous infusion of dopexamine caused a dose-related fall in blood pressure, renal vasodilatation and an increase in cardiac contractility and heart rate. Dopamine also increased cardiac contractility, and renal blood flow due to renal vasodilatation but without affecting heart rate. At the highest infusion rate, blood pressure was increased. Dopexamine and dopamine produced a similar incidence of panting and repetitive licking at 3 X 10(-8)mol kg-1 min-1 and emesis at 10(-7)mol kg-1 min-1, due to stimulation of dopamine receptors in the chemoreceptor trigger zone. Dopexamine produces a different cardiovascular profile from dopamine in the anaesthetized and conscious dog. Both compounds reduce renal vascular resistance, but in contrast to dopamine, dopexamine reduces afterload and produces only mild inotropic stimulation. These differences reflect contrasting activity at adrenoceptors.

Animals↗
PubMed1985

Relation of arachidonate metabolites to abnormal control of the pulmonary circulation in a child.

To evaluate the role of arachidonate metabolites in regulating pulmonary vascular tone, we performed multiple studies on a 17-month-old girl with idiopathic pulmonary hypertension, systemic arterial hypoxemia (due to ventilation-perfusion mismatching), and an elevated thromboxane A2 (TXA2) to prostacyclin (PGI2) ratio due to increased TXA2 (measured as their stable metabolites, TXB2 and 6-keto-PGF1 alpha, respectively). Intravenous infusions of PGI2 reduced mean pulmonary arterial pressure (from 80 to 47 mmHg), increased cardiac output (from 3.43 to 3.97 L/min), increased systemic arterial oxygen saturation (from 60 to 72 percent), and decreased the TXB2 to 6-keto-PGF1 alpha ratio (from 5.9 to 0.2); mean systemic arterial pressure was unchanged. Pharmacologically decreasing the TXB2 to 6-keto-PGF1 alpha ratio with administration of nifedipine or diltiazem also reduced pulmonary hypertension and increased systemic arterial oxygen saturation in this patient. Nifedipine and diltiazem decreased the ratio by decreasing TXB2. Prostacyclin decreased the ratio by increasing 6-keto-PGF1 alpha. These studies support the hypothesis that the balance between TXA2 and PGI2 is an important influence on pulmonary vascular tone.

6-Ketoprostaglandin F1 alpha↗
PubMed1985

Symmetrical peripheral gangrene and disseminated intravascular coagulation.

Symmetrical peripheral gangrene (SPG) is a rare syndrome associated with a multitude of underlying medical problems. We are adding three cases of SPG to the medical literature, all of which had disseminated intravascular coagulation (DIC). Each had an underlying illness that, to our knowledge, has not been previously associated with SPG: Hodgkin's lymphoma, Escherichia coli urinary tract infection with septicemia, and polymyalgia rheumatica. Review of the medical literature shows a high association between SPG and DIC. Symmetrical peripheral gangrene should therefore be considered a cutaneous marker of DIC. Early recognition and treatment of the underlying medical problem and DIC could be lifesaving.

Aged↗
PubMed1984

P-element transformation with period locus DNA restores rhythmicity to mutant, arrhythmic Drosophila melanogaster.

Mutations at the period (per) locus of Drosophila melanogaster disrupt several biological rhythms. Molecular cloning of DNA sequences encompassing the per+ locus has allowed germ-line transformation experiments to be carried out. Certain subsegments of the per region, transduced into the genome of arrhythmic pero flies, restore rhythmicity in circadian locomotor behavior and the male's courtship song.

Animals↗
PubMed1984

Molecular analysis of the period locus in Drosophila melanogaster and identification of a transcript involved in biological rhythms.

We have isolated and analyzed DNA sequences encompassing the period (per) locus of Drosophila melanogaster. The location of this clock gene was delimited by the molecular mapping of chromosome aberrations at or very near the per locus. At least five RNAs are transcribed from this region. One of these transcripts, a 0.9 kb species, is strongly implicated in per's control of biological rhythms. Two independently isolated arrhythmic mutations at the per locus dramatically reduce the level of this transcript. Furthermore, the level of the 0.9 kb transcript is strongly modulated during a light/dark cycle. We discuss evidence, from previously reported genetic and phenotypic analysis of per's function, suggesting that this region may be complex and that several gene products from the per region, including this 0.9 kb transcript, may be involved in the different aspects of normal rhythmicity influenced by this clock gene.

Animals↗
PubMed1984

Comparison of a monitored dose with a standard dose of chenodeoxycholic acid for gallstone dissolution.

The ability of chenodeoxycholic acid to dissolve gallstones was compared using different dosage regimens in two groups of 21 patients. The groups were closely matched for patient factors and stone characteristics known to influence the outcome of dissolution treatment. The patients in one group received a standard dose of chenodeoxycholic acid (15 mg/kg/day) taken at mealtimes. The patients in the second group received a bedtime dose of chenodeoxycholic acid which was sufficient to result in a proportion of this bile acid of 70% in the bile acid pool. This dose was monitored using serum bile acid profiles and varied within this test group (range 5.1-13.9 mg/kg/day). The number of patients whose stones completely dissolved in 12 months was similar in the standard-dose (7 of 21) and monitored-dose (8 of 21) groups. These results suggest that a bedtime dose of chenodeoxycholic acid, which is monitored to produce a level of 70% chenodeoxycholic acid in the biliary bile acid pool, is lower than the standard dose taken after meals but is of comparable efficacy. Lower dosage has the advantage of reducing costs and side effects from the drug, although serum bile acid profiling increases the cost of treatment.

Adult↗