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Biomedical subjects

M Hall

Publications and source records attributed to M Hall.

At least 145 records · Page 8Linked to original sources
PubMed1995

Proenzyme of Manduca sexta phenol oxidase: purification, activation, substrate specificity of the active enzyme, and molecular cloning.

Phenol oxidase (PO) was isolated as a proenzyme (pro-phenol oxidase, pro-PO) from the hemolymph of Manduca sexta larvae and purified to homogeneity. Pro-PO exhibits a M(r) of 130,000 on gel filtration and two bands with an apparent M(r) of approximately 100,000 on SDS/PAGE, as well as size-exclusion HPLC. Activation of pro-PO was achieved either by specific proteolysis by a cuticular protease or by the detergent cetylpyridinium chloride at a concentration below the critical micellar concentration. A cDNA clone for M. sexta pro-PO was obtained from a larval hemocyte cDNA library. The clone encodes a polypeptide of approximately 80,000 Da that contains two copper-binding sites and shows high sequence similarity to POs, hemocyanins, and storage proteins of arthropods. The M. Sexta pro-PO, together with other arthropod pro-POs, contains a short stretch of amino acids with sequence similarity to the thiol ester region of alpha-macroglobulins and complement proteins C3 and C4.

Amino Acid Sequence↗
PubMed1995

Evidence in postmortem brain tissue for decreased numbers of hippocampal nicotinic receptors in schizophrenia.

This study tests the hypothesis that nicotinic cholinergic receptors, including those sensitive to the antagonist alpha-bungarotoxin, are decreased in the hippocampus of schizophrenics. The hypothesis is derived from the finding that alpha-bungarotoxin causes a defect in the inhibitory gating of auditory-evoked potentials in laboratory animals that resembles a defect in auditory sensory gating observed in schizophrenics. Nicotine transiently normalizes this psychophysiological deficit in schizophrenic patients. Postmortem brain tissue was obtained from eight schizophrenic and eight age-matched nonschizophrenic subjects. Sections of the hippocampus were labeled with [125I alpha-bungarotoxin and imagined by autoradiography. Binding of the nicotinic agonist [3H]-cytisine was determined in tissue homogenates. alpha-Bungarotoxin labeled a population of putative interneurons in the hippocampus, primarily in the dentate gyrus and the CA3 region of Ammon's horn. This labeling was significantly decreased in the tissue from the schizophrenic patients, with seven or eight patients below the range of the nonschizophrenic subjects. There was also a significant decrease in the binding of cytisine. The results were not related to generalized hippocampal cell loss, drug exposure at time of death, or smoking history. This initial study suggests that schizophrenic patients have fewer nicotinic receptors in the hippocampus, a condition which may lead to failure of cholinergic activation of inhibitory interneurons, manifest clinically as decreased gating of response to sensory stimulation.

Adult↗
PubMed1995

Combined liver-kidney transplantation in primary hyperoxaluria type 1. Bone histopathology and oxalate body content.

In three patients with end-stage renal failure due to primary hyperoxaluria type 1, successful combined liver-kidney transplantation enabled us to assess the insoluble oxalate pool, which was compared with the histopathological changes observed in iliac crest biopsy specimens. Good correlation was observed between the histopathological grade of bone oxalosis and the estimated oxalate content of the body. In the end-stage of oxalate bone disease, hyperparathyroidism does not play a significant role in bone resorption, which appears to be the consequence of the granulomatous reaction induced by oxalate deposition. Combined liver-kidney transplantation should be performed long before this stage. Early hepatorenal grafting in uremia secondary to primary hyperoxaluria type 1 would avoid the deleterious clinical consequences of systemic oxalosis and shorten the duration of postransplant hyperoxaluria, which may compromise the course of kidney graft.

Adolescent↗
PubMed1995

Effects of resistance training on regional and total bone mineral density in premenopausal women: a randomized prospective study.

This study was designed to assess the effects of 18 months of resistance exercise on regional and total bone mineral density (BMD) and soft tissue lean mass (STL) in premenopausal women aged 28-39 randomly assigned to an exercise or control group. Twenty-two exercise and 34 control subjects completed the 18-month training study. All subjects were previously inactive and untrained women. Initial, 5-, 12- and 18-month assessments were made of total and regional BMD and total and regional STL using dual energy X-ray absorptiometry. All subjects consumed a 500 mg/day elemental calcium supplement throughout the study. Initial Ca intake without supplement averaged 1,023 mg/day in total sample. Serum levels of bone osteocalcin and dietary assessments using 12 randomly assigned days of diet records were also completed. Muscular strength was assessed from both 1 repetition maximum (RM) testing of 10 weightlifting exercises and by peak torque for hip abduction/adduction and knee extension/flexion. Training increased strength by 58.1% based on 1 RM testing and by 33.8% based on isokinetic testing at 18 months versus baseline. BMD increased significantly above baseline at the lumbar spine for the exercise group at 5 months (2.8%), 12 months (2.3%), and 18 months (1.9%) as compared with controls. Femur trochanter BMD increased significantly (p < 0.05) in the exercise group at 12 months (1.8%) and 18 months (2.0%) but not at 5 months (0.7%) as compared with controls. No changes in total BMD, arm BMD, or leg BMD were found. There was a 20% increase in BGP in the exercise group as compared with controls at 5 months and this difference was maintained throughout the study. For STL, significant increases for total, arm, and leg were found at 5, 12, and 18 months for the exercise group versus control ranging from 1-6% over baseline. These results support the use of strength training for increasing STL and muscular strength with smaller but significant regional increases in BMD in the premenopausal population.

Absorptiometry, Photon↗
PubMed1995

A psychophysiological inquiry into the nature of the Sokolovian orienting response comparator model: skin conductance and EEG data.

The mechanisms which trigger the orienting response (OR) are still the subject of lively debate. Sokolov (1990) proposes the development of a multidimensional model of the physical parameters of stimulation. Recent OR research has shown that the skin conductance OR (SCOR) is related to task demands and controlled processing, although this is not so clear for central physiological indexes of orienting. Seventy-three subjects performed visual discriminations of stimuli within a warning-stimulus paradigm. The physical complexity of stimuli and their task relevance were manipulated within subjects, while the nonspecific effects of workload were controlled with a group factor. SCORs were measured concurrently with 1-s epochs of EEG alpha and theta power from Fz, Cz, Pz, and Oz. Neither index was reliably affected by the physical complexity of stimulation alone. However, both higher task relevance and higher workload significantly increased the magnitude of EEGORs and SCORs. Task averages of central and autonomic activity showed an overall pattern of covariation, but a second-by-second breakdown of EEG spectra suggests that the SCOR may be an aggregate of the activation of diverse brain mechanisms responsible for physiological orienting. The results are consistent with a model of orienting as a continuous dimension of resource allocation to anticipated and current task demands, rather than with the abrupt dichotomy between voluntary and involuntary orienting. Implications for the classical OR Sokolovian model are discussed.

Analysis of Variance↗
PubMed1995

The effects of L-dihydroxyphenylalanine on alertness and mood in alpha-methyl-para-tyrosine-treated healthy humans. Further evidence for the role of catecholamines in arousal and anxiety.

Treatment with alpha-methyl-para-tyrosine (AMPT), a catecholamine synthesis inhibitor, has been shown to produce pronounced increases in sleepiness and mild increases in negative mood and anxiety when administered to healthy male adults. The present study was conducted to ascertain whether these effects of AMPT are secondary to decreases in brain catecholamines or whether they represent nonspecific drug effects. Forty-one healthy males were randomized to one of four treatment groups. (1) Treatment with AMPT alone (AMPT/placebo); (2) treatment with AMPT plus L-dopa/carbidopa (AMPT plus L-dopa/carbidopa); (3) treatment with L-dopa/carbidopa alone (placebo plus L-dopa/carbidopa); or (4) treatment with placebo alone (placebo plus placebo). Repeated measures of alertness, mood, and anxiety were obtained over a three-day period of drug treatment and following drug discontinuation. As before, AMPT treatment led to increased sleepines. In addition, AMPT treatment led to decreased calmness, increased tension and anger, and a trend for increased depression. Replacement of catecholamine stores with L-dopa reversed the effects of AMPT and was associated with a more rapid recovery from AMPT's effects. These findings indicate that AMPT's effects on alertness and anxiety are catecholamine-specific. Further, they provide additional evidence that catecholamines are involved in the regulation of normal states of arousal, and they are consistent with the view that brain catecholaminergic dysregulation is involved in pathological anxiety states.

Adult↗
PubMed1995

Oxidation and genotoxicity of fecapentaene-12 are potentiated by prostaglandin H synthase.

The potential importance of prostaglandin H synthase (PGHS) in the genotoxicity of fecapentaene-12 (fec-12) has been indicated by the finding that non-steroidal anti-inflammatory agents (NSAIDs) block the induction of oxidative DNA base damage by fec-12 in HeLa cells. To further investigate the role of PGHS in the metabolic 'activation' and genotoxicity of fec-12, we have measured: (i) oxygen uptake by fec-12 with purified preparations of PGHS; and (ii) the induction of DNA single-strand breaks (SSBs) in HeLa cells exposed to fec-12 in the absence or presence of PGHS inhibitors. Oxygen uptake occurred spontaneously with fec-12 alone but was stimulated 3-fold by the presence of PGHS. The potentiation of fec-12 oxygenation by PGHS was independent of arachidonate and inhibited 45% by indomethacin (INDO). Methylphenylsulphide (MPSI), a reducing substrate expected to compete with fec-12 in peroxidase-dependent co-oxidation reactions, also inhibited PGHS-mediated oxygen uptake with fec-12 by 55%. These results, together with the observation that the inhibitory effects of these agents in combination were additive, suggest that both the cyclooxygenase and peroxidase components of PGHS are involved in the oxidation of fec-12. INDO and MPSI also blocked the induction of DNA SSBs by fec-12 in HeLa cells, indicating that both components of PGHS are also involved in potentiating the genotoxicity of fec-12. It is proposed that this occurs in two ways: firstly, by formation of highly reactive fec-12 hydroperoxides which would generate oxygen radicals through Fenton-like reactions, and secondly, by the generation of oxygen radicals through peroxidase-mediated co-oxidation of fec-12.

Cyclooxygenase Inhibitors↗
PubMed1995

Identification of an Mhc-DPB1 allele involved in susceptibility to experimental autoimmune encephalomyelitis in rhesus macaques.

Experimental autoimmune encephalomyelitis (EAE) is an inducible autoimmune disorder that in rodents is known to be influenced by genetic background, specifically the Mhc class II region. Immunization of a group of outbred rhesus macaques with bovine high homogenate results in induction of the disease in approximately 65% of the animals. No clear association between the Mamu-DR or -DQ subregion of the rhesus macaque MHC (MhcMamu) and susceptibility or resistance to the disease has been documented. In this communication we describe a CD4+ Th cell line, isolated from an animal diagnosed with EAE, which proliferated in response to purified bovine myelin basic protein (MBP), a major constituent of the myelin sheath surrounding nerve cells. More specifically it only recognized a peptide including residues 61-82 of the molecule. Analysis of the T cell receptor (Tcr) usage of this MBP reactive T cell line showed functional transcripts for only two members of the V alpha 1 and one of each of the V beta 3 and V beta 6 families. The antigen-specific proliferative response was inhibited by a mAb reactive with MHC-DP molecules. Molecular analysis of the Mamu-DP region, in concert with allogeneic antigen presentation studies, demonstrated that the Mamu-DPB1*01 gene product functions as the restriction element for MBP peptide presentation. Retrospective analyses showed that this particular allele is frequently found in the group of EAE susceptible animals but is absent in the resistant animals (P < 0.01). As a consequence, the Mamu-DPB1*01 allele may represent one of the risk factors involved in determining susceptibility to EAE in an outbred population of rhesus macaques.

Alleles↗
PubMed1995

The spontaneous reporting of adverse drug reactions by nurses.

In an attempt to improve the low reporting rate of adverse drug reactions (ADR) we examined the potential for hospital nurses to report ADRs through a spontaneous 'yellow card' system. Over 14 months 100 cards were received (compared with 28 cards from doctors). Although reports from doctors for the same period were of a more substantial nature, nurses nevertheless reported many life threatening (17%) or moderately severe (76%) reactions. Nurses identified uncertainty concerning their role and deficient in-service education on drug therapy as major constraints in their participation. Given their unique position in drug administration and recording observations on patients, we believe that nurses could contribute significantly and in a complementary fashion to the spontaneous reporting of adverse reactions.

Adverse Drug Reaction Reporting Systems↗
PubMed1995

Role of elevated plasma soluble ICAM-1 and bronchial lavage fluid IL-8 levels as markers of chronic lung disease in premature infants.

BACKGROUND: Pulmonary neutrophilia characterises both the relatively transient inflammation associated with infant respiratory distress syndrome (IRDS) and the persistent inflammation of chronic lung disease. The possibility that persistently raised markers of inflammation indicate the development of chronic lung disease in low birth weight (< 1730 g) preterm (< 31 weeks) infants was therefore investigated. METHODS: Soluble ICAM-1 (sICAM-1) levels in plasma, and interleukin (IL)-8 and myeloperoxidase (MPO) levels in bronchial lavage fluid (BLF) obtained from 17 infants on days 1, 5, and 14 following birth were measured and correlations with the number of neutrophils in BLF sought. Peripheral neutrophils were isolated on Polymorphoprep and chemotactic responsiveness to IL-8 was assessed using micro Boyden chambers. RESULTS: Sixteen infants developed IRDS and, of these, 10 infants subsequently developed chronic lung disease. Levels of IL-8 in BLF at 14 days of age correlated with the long term requirement for intermittent positive pressure ventilation (IPPV). Interleukin 8 levels in BLF correlated with neutrophil numbers and MPO concentration, suggesting both recruitment and activation in response to this cytokine. Antibody depletion studies showed that approximately 50% of total neutrophil chemotactic activity in BLF was due to IL-8. No difference in peripheral neutrophil chemotactic responsiveness at any age was observed for infants with IRDS or chronic lung disease. Plasma soluble intercellular adhesion molecule (sICAM-1) was higher at 14 days of age in infants who developed chronic lung disease than in those with resolving IRDS, and correlated with severity of disease, as indicated by duration of IPPV. CONCLUSIONS: The results indicate that high levels of plasma sICAM-1 and IL-8 in BLF at day 14 correlate with the development of chronic lung disease and indicate the severity of disease.

Biomarkers↗
PubMed1995

Adults' responses to self-injurious behavior. An experimental analysis using a computer-simulation paradigm.

The behavior of staff who care for people with mental retardation has been identified as a significant factor in the development and maintenance of challenging behaviors. In a recent analysis, Hastings and Remington (1994a) suggested that both environmental contingencies and rules from other people may affect staff actions. The present study tested this analysis by asking participants to respond to a computer simulation of a work situation involving the care of two individuals who engaged in self-injurious behavior. Fifty participants "interacted" with an attention-seeker and a social-avoider on a simulated teaching task. Results showed that rules were the main factor governing performance. The aversive nature of the contingencies between the self-injury and participants' "attending" behavior also appeared to be influential. The implications of these results for work with care staff, the analysis of challenging behaviors, and experimental research on rule-governed behavior are discussed.

Adolescent↗
PubMed1995

Homelessness and substance use among alcohol abusers following participation in project H&ART.

Project H&ART was a randomized intervention trial for homeless alcohol abusers in Albuquerque, N.M. Interventions were four months in duration and included: a high intensity program (case management plus peer-supervised housing), a medium intensity group (peer-supervised housing only); a housed, and a nonhoused control group. Clients were interviewed at baseline and re-interviewed ten months following program entry to determine substance use, housing stability and employment status. Program graduation rates were about 25% for the three housed groups. The outcome evaluation revealed significant within groups improvements in all of the outcomes, no between groups or racial outcome differences, and more favorable alcohol use and housing stability outcomes among program graduates than dropouts. On follow-up, women in the study had fewer days of alcohol use and had more days of stable housing, but were less likely to be employed, compared with men. We suggest that clients' personal motivation for recovery, rather than program-related factors, were most influential in determining outcomes.

Adolescent↗
PubMed1995

Induction of rodent hepatic drug-metabolizing enzyme activities by the novel anticonvulsant remacemide hydrochloride.

Remacemide hydrochloride [FPL 12924AA; 2-amino-N-(1-methyl-1,2-diphenylethyl) acetamide hydrochloride] is being evaluated as a novel neuroprotective treatment for epilepsy and stroke. Preliminary safety evaluation studies in the rat have shown that repeated doses of the compound produce histological and biochemical changes consistent with hepatic enzyme induction. To examine this further, the levels and activities of the major drug metabolizing cytochrome P450 (CYP) subfamilies (CPY1, CYP2, and CYP3) were monitored in microsomal samples from male Sprague-Dawley rats dosed by gavage with FPL 12924AA (250 mg base.kg-1.day-1 for 28 days) or an equivalent volume of vehicle (controls). The interpretation of the findings was aided by comparison with the effects of phenobarbitone (75 mg.kg-1.day-1 ip for 4 days) and beta-naphthoflavone (a single intraperitoneal dose at 80 mg.kg-1.day-1). No significant changes in total hepatic P450 levels (1.44 +/- 0.40 nmol.mg-1 vs. 1.31 +/- 0.19 nmol.mg-1 in controls) or ethoxyresorufin O-deethylase activity (a CYP1A induction probe) were observed after remacemide treatment. The pattern of induction produced by remacemide was very similar to that observed with phenobarbitone. The nonspecific CYP-dependent reaction ethoxycoumarin O-deethylation was induced approximately 2-fold. The specific CYP2B markers pentoxyresorufin O-depentylase and 16 beta-hydroxytestosterone production were both increased markedly by FPL 12924AA (approximately 100- and 20-fold, respectively). 2 beta- and 6 beta-Hydroxytestosterone production were also elevated, indicating the induction of CYP3A1/2. Similar effects on isoform-selective P450-dependent activities were observed in male and female mice treated with remacemide as part of a dose-ranging study.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetamides↗
PubMed1994

Possible pathogenic role of IgE in Henoch-Schönlein purpura.

The incidences of clinical and biological markers of atopy were investigated in 16 children with IgA nephropathy (IgAN) (group A) and in 22 with Henoch-Schönlein purpura nephritis (HSPN) (group B). The incidence of increased plasma IgE levels according to age-matched normal values was significantly higher in group B (17/22, 77%) than in group A (7/16, 44%) (P < 0.05). Although not significant, the incidences of positive RAST tests and of a history of typical atopic symptoms were also higher in group B [10/22 (45%) and 11/22 (50%), respectively] than in group A [4/16 (25%) and 5/16 (31%), respectively]. Moreover, IgE deposits were demonstrated by a peroxidase/anti-peroxidase method on cutaneous Langerhans and mast cells in 4 of 6 patients with HSPN. Thus immunoallergy might account, in some cases, for the cutaneous, intestinal and pulmonary signs observed in HSPN, but not in IgAN. We postulate stimulation of IgE-sensitized mast cells by specific antigens in the presence of IgA circulating immune complexes (CIC), release of vasoactive substances, increased capillary permeability and perivascular deposition of IgA CIC.

Adolescent↗
PubMed1994

Effect of hyperfiltration on long-term follow-up of glomerular filtration rate in male Wistar rats.

It has been suggested that a prolonged course of hyperfiltration could lead to progressive deterioration of renal function. In order to test this hypothesis, the following protocol was applied to 60 male Wistar rats. At 12 weeks of life, the rats were submitted to a surgical procedure: sham operation (25 rats), unilateral nephrectomy (25 rats) or 3/4 nephrectomy (10 rats). The three groups were again divided into two subgroups: one with high-protein intake (36%) and one with a low-protein intake (12%). In order to avoid any additional traumatic procedure which could shorten the animal's life, the glomerular filtration rate (GFR) was measured without blood sampling, using a previously validated technique based on an image recorded by a gamma camera between the 9th and the 10th min after intravenous injection of 99m technetium diethylenetriaminepentaacetate (DPTA). The sum of both kidneys and bladder activity was expressed as a percentage of the injected dose. The test was performed before surgery and every month thereafter. Six weeks after surgery, the highest filtration rate was found in the rats with "two kidneys/high-protein diet", followed by the "two kidneys/low-protein diet", the "one kidney/high-protein diet", the "one kidney/low-protein diet" and the "1/2 kidney". The overall GFR in the one kidney/high-protein diet rat and in the 1/2 kidney rat was respectively 80% and 55% of the pre-operative values. Until 109 weeks of age, the survival rate was comparable in the five groups of rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Is antenatal care apportioned according to obstetric risk? The Scottish antenatal care study.

A retrospective cohort study of case records of antenatal care was carried out to describe and compare antenatal services in Scotland according to type of hospital and risk category of women. The study took place at 15 randomly selected maternity hospitals which were divided into teaching hospitals (n = 5), rural catchment hospitals (n = 2), and district general hospitals divided by size as those with 1000-1699 deliveries per year (n = 4), and those with > or = 1700 deliveries per year (n = 4). The subjects were 3574 (87.7 per cent) of 4069 eligible women who delivered in the last quarter of 1989 at these hospitals. Of those 3574, 19 per cent (675) were considered to be high risk at booking, 64 per cent (2899) continued low risk throughout their pregnancy and the remaining 17 per cent (608) changed from low risk to high risk during pregnancy. The main outcome measures were the number, timing, location and supervision of antenatal visits and antenatal admissions in relation to hospital types and obstetric risk categories, and adverse pregnancy outcomes in relation to risk categories. It was found that 97 per cent of all women had care shared by general practitioner (GP) and hospital specialist agreement. The majority (64 per cent) of antenatal visits took place away from the hospital of delivery, with GPs responsible for the largest proportion of all antenatal visits (43.5 per cent) compared with specialist hospital doctors (36 per cent) and midwives (11.5 per cent). Wide variations in the use of different personnel groups to deliver antenatal care were observed between hospitals, particularly in the use of midwives to supervise visits (4-34 per cent). The median number of antenatal visits was 14 (mean 13.9, SD 3.9). Within hospital types the differences in the mean number of antenatal visits between the three risk categories were small (one to two visits) and the direction inconsistent. In all types of hospital, outset high-risk women and those who changed to high risk were more likely to have hospital admission than those who continued as low risk. Significantly more women in the high-risk categories experienced adverse pregnancy outcomes than women who continued at low risk.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1994

When is "impulsiveness" not impulsive? The case of hyperactive children's cognitive style.

On two computerized versions of the Matching Familiar Figures Test (MFFT; Kagan, Child Development, 36, 609-628, 1965) pervasively hyperactive and matched control children had to identify a target from among five similar foils. One version had a temporal structure similar to the manual MFFT and trial length was determined by response speed. Hyperactive children behaved in an "impulsive" manner; they responded more quickly and made more mistakes than controls. Despite this they completed each trial more quickly than controls by identifying the target. On the second version, the length of each trial was fixed at 45 seconds. Although both groups were equally "reflective", hyperactive children still made more mistakes. Implications of these results for research in impulse control in general and hyperactivity in particular are discussed.

Attention Deficit Disorder with Hyperactivity↗