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Biomedical subjects

M Hall

Publications and source records attributed to M Hall.

At least 127 records · Page 7Linked to original sources
PubMed1996

Evaluation of suprapubic bladder aspiration for detection of group B streptococcal antigen by latex agglutination in neonatal urine.

Our objective was to determine whether urine collection by suprapubic bladder aspiration (SBA) improves the specificity of the group B streptococcal (GBS) latex agglutination (LA) test by avoiding contamination of urine with GBS from perineal and rectal colonization that can result in a positive LA test in an uninfected infant when the urine is collected by bag. Part 1 consists of a retrospective review of the medical records of 113 infants who had urine collected by SBA for GBS LA testing as part of evaluation for possible sepsis. The sensitivity and specificity of the urine LA test was assessed by comparing it with blood culture results. In part 2, a prospective analysis was performed of 19 newborns who had rectal and vaginal/penile cultures as well as urine by SBA and bag for GBS cultures and LA. Results of LA testing on urine collected by both of these methods were compared with results of urine, perineal, and rectal cultures. In the retrospective review of GBS LA testing performed on 113 consecutive urine specimens collected by SBA from neonates being evaluated for suspected sepsis, the sensitivity and specificity were 67% and 89%, respectively, when compared with blood culture results. Twelve infants who had a positive LA test result but a sterile blood culture (BC-,LA+) were compared with 95 infants with both blood cultures and urine LA tests negative for GBS (BC-, LA-). BC-, LA+ infants were more likely than those with BC-, LA- to have an immature to total neutrophil (I/T) ratio > or = 0.16 at 12 and 24 hours (p = 0.04 and 0.02, respectively). In the prospective study, we found that a positive GBS LA test can be due to perineal contamination and possibly to gastrointestinal absorption of GBS antigen. No false positive LA test results occurred on urine obtained by SBA; however, use of this method failed to detect the one infant with GBS bacteremia. Because of suboptimal sensitivity and specificity, use of the GBS LA test on urine obtained either by SBA or bag cannot be recommended for diagnosis of early onset GBS disease.

Antigens, Bacterial↗
PubMed1996

Hyperactivity and delay aversion. III: The effect on cognitive style of imposing delay after errors.

The claim that impulsiveness associated with hyperactivity is the result of deficits in inhibition of responses over time was examined. The cognitive style of hyperactive children was studied under two conditions. As in previous studies hyperactive children appeared impulsive (i.e. gave shorter latencies and made more errors than controls) under conditions where this style led to shorter trials. In contrast, in a revised condition where each error led to an enforced/fixed trial length, hyperactive children waited as long as controls before responding, but still made more errors. Hyperactive children withheld responses when this offered them the best chance of avoiding extra delay. They were however, unable to use the extra time provided as effectively as controls. The link between hyperactive children's aversion to delay and their poor use of time is discussed.

Child↗
PubMed1996

Application of 16S rRNA gene PCR to study bowel flora of preterm infants with and without necrotizing enterocolitis.

The purpose of the present study was to determine the extent to which bacteria not detected by culture contribute to the microbial flora of the bowel of preterm infants with and without neonatal necrotizing enterocolitis (NEC). Fecal samples from 32 preterm infants in special care baby units including samples from 10 infants with NEC were examined by culture and PCR amplification of the 16S rRNA gene (rDNA). The 16S rDNA V3 region was amplified with eubacterial primers, and the amplification products derived from the fecal sample DNA were compared with the products from individual cultured isolates by PCR and denaturing gradient gel electrophoresis (PCR-DGGE), allowing the DNA from uncultured bacteria to be identified. For the 22 infants without NEC weekly samples were examined for a mean of 5.3 postnatal weeks. The total number of types detected by culture combined with PCR-DGGE was 10.1 per infant, of which PCR-DGGE contributed 10.4% of the types identified. Additional types detected by PCR-DGGE were found in 14 (63.6%) of the 22 infants. The majority of the sequences associated with uncultured bacteria showed > 90% 16S rDNA sequence identity with sequences from culturable human enteric flora, and all were found in single infants with the exception of sequences indistinguishable by DGGE from seven infants. These sequences showed > 90% sequence identity with the 16S rDNA of Streptococcus salivarius and may have been derived from upper gastrointestinal or respiratory tract flora. In the present study uncultured bacteria detected by PCR-DGGE were no more frequent in fecal samples from infants with NEC than in samples from infants without NEC, although these findings do not exclude the possibility of unrecognized bacteria associated with the mucosa of the small intestine of infants with NEC.

Bacteria↗
PubMed1996

High relapse rate after discontinuation of adjunctive medication for elderly patients with recurrent major depression.

OBJECTIVE: The authors documented outcomes of elderly depressed patients requiring adjunctive medication during acute-phase pharmacotherapy because of slow or partial response to nortriptyline. Twenty-eight patients (17.7%) received inpatient care at some point during acute-phase treatment. METHOD: Rates of response, relapse, and sustained remission were examined in 158 elderly patients with recurrent major depression, grouped by whether they received brief treatment with adjunctive medication (lithium, perphenazine, or paroxetine) (N = 39) or did not (N = 119). RESULTS: The group receiving adjunctive medication had a lower rate of response to acute therapy (64.1% versus 83.2%), a higher relapse rate during continuation therapy (52.0% versus 6.1%), and a lower rate of sustained remission (recovery) (48.7% versus 76.5%) than did the group without augmentation. CONCLUSIONS: Elderly depressed patients requiring augmented pharmacotherapy to achieve remission may need continuation of adjunctive medication to remain well and to avoid early relapse. Alternatively, factors that lead to augmentation in the first place (e.g., heightened anxiety) may also increase the risk of relapse.

Age Factors↗
PubMed1996

Therapeutic monitoring of continuous infusion etoposide in small-cell lung cancer.

PURPOSE: To investigate the feasibility of therapeutic monitoring of etoposide at different plasma concentrations of the drug, and the resulting pharmacodynamic effects of such an approach. PATIENTS AND METHODS: Forty-nine previously untreated small-cell lung cancer (SCLC) patients received single-agent etoposide every 3 weeks by continuous infusion over 5 days. Plasma etoposide concentrations were monitored 18 and 66 hours into the infusion to permit dose modification. The first cohort of 15 patients began treatment with etoposide 2 micrograms/mL, with dose escalation to 3 micrograms/mL for cycles 3 and 4 and 4 micrograms/mL for cycles 5 and 6, toxicity permitting. The second cohort of 34 patients commenced at 3 micrograms/mL, with dose escalation to 4 and 5 micrograms/mL on cycles 3 and 5, respectively. RESULTS: Mean plasma etoposide concentration during the first treatment cycle was 93.4% +/- 26.6% of the target level at 18 hours (57% of patients within +/- 20% of the target) and 98.9% +/- 14.5% of the target level at 66 hours (82% of patients within +/- 20%). Hematologic toxicity was more pronounced in those treated with 3 micrograms/mL versus 2 micrograms/mL (median nadir neutrophil count, 1.3 v 2.6 x 10(9)/L, P = .032). Tumor responses, typically documented by the third cycle, were similar in each cohort (71% in patients commenced at 2 micrograms/mL and 70% at 3 micrograms/mL). Treatment cohort was not independently predictive of survival. CONCLUSION: Therapeutic monitoring of infusional etoposide is feasible and dramatically reduces interpatient pharmacokinetic variability. Although this was a small nonrandomized trial, the observation of different hematologic toxicity at the two starting concentrations but similar antitumor activity further suggests that these effects may be associated with different plasma etoposide concentrations.

Antineoplastic Agents, Phytogenic↗
PubMed1996

The correlation between neuropsychological and neuroanatomic changes over time in asymptomatic and symptomatic HIV-1-infected individuals.

To determine the relationship between neuroanatomic and neuropsychological changes in both asymptomatic and symptomatic HIV-1-infected individuals, we conducted a longitudinal study of 47 HIV-infected individuals, 15 of whom were asymptomatic and 32 of whom had either AIDS-related complex or AIDS. To measure neuroanatomic change over a 30-month period, we conducted quantitative MRI measures of bicaudate/brain ratio (BCR) and bifrontal/ brain ratio. A comparison of change over time between BCR and neuropsychological performance showed a correlation between increase in atrophy and worsening in certain cognitive functions. The correlation held for both asymptomatic and symptomatic groups, with more pronounced changes in the symptomatic group.

AIDS Dementia Complex↗
PubMed1995

Identification of the major lipoproteins in crayfish hemolymph as proteins involved in immune recognition and clotting.

Lipid-containing hemolymph proteins from males of the crayfish Pacifastacus leniusculus were isolated by density gradient ultracentrifugation. Two major lipoproteins, one high density lipoprotein (HDL) and one very high density lipoprotein (VHDL), were characterized. The HDL and the VHDL were found to be identical to two proteins previously studied for their roles in immune recognition and hemolymph clotting, namely the beta-1,3-glucan binding protein and the clotting protein. These results imply that crayfish lipoproteins have dual functions, and that they are involved in immunity, hemolymph clotting, and lipid transport in these animals. Also, the oxygen-transporting protein hemocyanin was found to have a small lipid content.

Amino Acid Sequence↗
PubMed1995

Evidence for different modes of action of cyclin-dependent kinase inhibitors: p15 and p16 bind to kinases, p21 and p27 bind to cyclins.

A number of low molecular weight proteins have recently been identified that specifically inhibit the function of cyclin-dependent protein kinases in mammalian cells. These fall into two distinct families based on primary sequence comparisons and probable modes of action. Using a simple in vitro binding assay, we show that p21CDKN1 and the related p27KIP1 can efficiently interact with cyclins D1, D2, D3, E and A, and to a lesser extent with cyclin B. By generating a deleted form of cyclin D1 that binds to p21 and p27 but not to Cdks, we confirm that these interaction do not depend on stoichiometric amounts of the relevant kinase subunit. Moreover, p21 and p27 do not detectably associated with kinase subunits unless a cyclin is present. This is in sharp contrast to the properties of p16CDKN2 and p15MTS2/INK4b which bind to Cdk4 and Cdk6 in the absence of any cyclin. These data suggest that p21 and p27 act as broad spectrum regulators of cyclin dependent kinase function by participating in ternary complexes whereas the p16 family specifically interfere with the formation of cyclin D-dependent kinase complexes.

Carrier Proteins↗
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↗