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Biomedical subjects

J Hall

Publications and source records attributed to J Hall.

At least 217 records · Page 12Linked to original sources
PubMed1996

The effect of branched-chain amino acid-enriched parenteral nutrition on gut permeability.

In situations of catabolic stress, the gut becomes atrophic and has a diminished barrier function as evidenced by an increased permeability to a variety of molecules. It is known that the parenteral administration of branched-chain amino acids (BCAA) reduce gut atrophy. The aim of this study was to examine the effect of BCAA-enriched solutions of parenteral nutrients on gut permeability. A secondary aim was to observe the association between gut permeability and variables that have been used to assess jejunal atrophy. Central venous lines were inserted into 30 rats before randomization to receive nutritional support with: (1) a conventional parenteral solution (CPN), (2) A 2.0% BCAA-enriched solution (BCAA), or (3) rat food ad lib (Rat Food). The rats were assessed after 7 d for nutritional status, gut morphology, and gut permeability ratio (ratio of the permeability to 14C raffinose and 3H mannitol). We found that rats in the Rat Food Group lost the least amount of weight, had the least amount of jejunal atrophy, and had better preservation of barrier function as determined by gut permeability. When compared with the CPN Group, the BCAA Group had better preservation of jejunal morphology and protein content (p < 0.05), but a similar gut permeability. A cross-correlation matrix demonstrated a significant negative correlation between permeability to mannitol and mucosal weight, mucosal protein content and mucosal DNA content. Branched-chain amino acid-enriched parenteral nutrition reduced gut atrophy but not the gut permeability associated with parenteral nutrition. In the parenterally nourished rat model, atrophy of the jejunum is associated with increased permeability to small molecules.

Amino Acids, Branched-Chain↗
PubMed1996

The measurement of utility in multiphase health states.

To examine the validity of the additive quality-adjusted life year model used to evaluate a multiphase health state, data from a pilot study of mammography were used to determine whether the values assigned to a multiphase postmastectomy health state could be estimated from a combination of the independently rated constituent health state values. The results suggest that they cannot.

Adult↗
PubMed1996

Detailed behavioral analysis of water maze acquisition under APV or CNQX: contribution of sensorimotor disturbances to drug-induced acquisition deficits.

N-methyl-D-aspartate (NMDA) receptor antagonists disrupt acquisition of the water maze and cause sensorimotor disturbances. In a detailed behavioral analysis in male rats, it was found that the NMDA antagonist DL-2-aminophosphonovaleric acid (APV) caused sensorimotor disturbances in behaviors required for maze performance and that these correlated with acquisition impairments in both hidden and visible platform versions of the maze. Behavioral disturbances included thigmotaxic swimming, swimming over and deflecting off the platform, abnormal swim behavior, and hyperactivity. Rats familiar with the behavioral strategies involved in the task performed normally under APV. The results are consistent with the known role of NMDA receptors in sensorimotor mechanisms and suggest that drug-induced sensorimotor disturbances contributed to poor acquisition scores in naive rats. NMDA may contribute to but does not appear to be essential for spatial learning in the water maze.

2-Amino-5-phosphonovalerate↗
PubMed1996

Role of formal instruction and informal practice in learning to drive.

Learning to drive a motor vehicle is important for the mobility of the majority of people in industrialized countries. Although a great deal is known about the acquisition of psychomotor skills in the laboratory and in some other practical settings, there has been little scientific study of learning to drive. One major practical question concerns the value of formal tuition with a qualified instructor and informal practice with friends or relatives. This paper reports a cross-sectional study of 805 learner drivers in the UK who had undergone at least 5 h of formal tuition to examine associations between their history of formal tuition and practice and current levels of skill and confidence as assessed by both pupils and their instructors. The results indicated an increase in instructor ratings of pupil skill with both increasing practice and tuition. However, the relationship between tuition and instructor-rated skill was only observed in pupils who had had no practice. Pupils' self-confidence did not increase with either tuition or practice; instructors' feelings of confidence in and safety with the pupil increased with pupils' prior hours of practice but not tuition. Instructors' ratings of the likelihood that pupils would pass the driving test first time were positively associated with prior hours of practice and negatively associated with prior formal tuition. The results suggest that informal practice constitutes an important element of the process of learning to drive. Longitudinal and experimental studies are now required to confirm this finding and to establish whether recommendations should be made for a component of driving tuition involving supervised practice.

Adolescent↗
PubMed1996

Effects of gamma-aminobutyric acid on human sperm motility and hyperactivation.

This study was undertaken to evaluate the effects of gamma-aminobutyric acid (GABA) and GABAergic agonists and antagonists on sperm kinematic parameters and hyperactivation, evaluated by a computer-assisted semen analysis (CASA) system, and intracellular cAMP content in 22 normozoospermic semen samples. Because of the possible interaction of progesterone with the GABAA receptor, we also evaluated the effects of progesterone on these parameters. GABA increased beat cross frequency, curvilinear velocity (VCL), the percentage of spermatozoa moving with an average path velocity > 10 microns/s (active) and hyperactivation, and decreased linearity and straightness. Bicuculline, a GABAA receptor antagonist, antagonized the effects of GABA on all these parameters except the percentage of active spermatozoa. Muscimol, a GABAA receptor agonist, increased VCL, the percentage of active spermatozoa, and hyperactivation by about the same extent as GABA, suggesting the involvement of the GABAA receptor. However, the GABAB receptor also seems to mediate some of the effects of GABA, because baclofen, a selective agonist for this receptor, increased significantly the percentage of active spermatozoa and hyperactivation. The effect of baclofen on this latter parameter was, however, less pronounced than that obtained with GABA or muscimol. Progesterone had the same effects as GABA on sperm kinematic parameters and hyperactivation and the simultaneous presence of both compounds was not more effective than each single one. GABA and progesterone did not have any effect on intracellular cAMP content. In conclusion, GABA modulated sperm kinematic parameters and increased hyperactivation. These effects have the same magnitude of those produced by progesterone and seem to be mediated mainly by the GABAA receptor. We speculate that GABA may be a physiological regulator of sperm function.

Baclofen↗
PubMed1996

Validity of DSM-IV ADHD predominantly inattentive and combined types: relationship to previous DSM diagnoses/subtype differences.

UNLABELLED: Since 1980, three different diagnostic nomenclatures have been published regarding attention-deficit hyperactivity disorder (ADHD). These changing conceptualizations and diagnostic criteria have generated considerable confusion. OBJECTIVE: To examine the multidimensional DSM-IV ADHD criteria in relation to how children and adolescents with a previous DSM-III ADD diagnosis or a DSM-III-R ADHD diagnosis are diagnosed according to DSM-IV criteria. METHOD: Children whose original diagnoses were according to DSM-III and DSM-III-R criteria received retrospective diagnoses according to DSM-IV criteria. RESULTS: Predominantly inattentive (n = 30) and combined types (n = 26) were compared on their previous DSM-III and DSM-III-R diagnoses and on demographic, behavioral, cognitive, and comorbidity variables. Predominantly inattentive and combined type diagnoses corresponded with DSM-III ADD/WO and ADD/H diagnoses, respectively. The DSM-III-R ADHD diagnosis did not correspond with either DSM-IV subtype. Children with the combined type diagnosis had more externalizing codiagnoses, and their parents reported more externalizing, delinquent, and aggressive behaviors. Children with the predominantly inattentive type had more math learning disability codiagnoses. CONCLUSION: Results support a multidimensional conceptualization of ADHD. There exists close correspondence between the DSM-III ADD/WO type and the DSM-IV predominantly inattentive type and between the DSM-III ADD/H type and the DSM-IV combined type.

Achievement↗
PubMed1996

Determination of the efficacy of topical oral pilocarpine for postirradiation xerostomia in patients with head and neck carcinoma.

Pilocarpine hydrochloride suspended in a candy-like pastille was evaluated as a topical treatment for radiation-induced xerostomia in head and neck cancer patients. This local delivery system, which differs from systemically administered pilocarpine preparations, was developed to hopefully maximize the local response and minimize the systemic side effects. A prospective, randomized, double-blind, placebo-controlled trial was undertaken to determine objective and subjective efficacy in reversing the decrease in salivation. Forty previously irradiated patients received increasingly higher pilocarpine dosages in pastilles for 5 successive weeks. At each successive dose of pilocarpine, no significant increased salivation was noted. However, 25 (74%) of 34 patients reported that pilocarpine alleviated their subjective xerostomia. Topical pilocarpine administration has shown similar results to previous systemic delivery methods for radiation-induced xerostomia, but with improved patient tolerance.

Administration, Oral↗
PubMed1996

Temporal cell-type-specific mRNA expression of O6-methylguanine-DNA methyltransferases in liver of rats treated with dimethylnitrosamine.

The intercellular distribution of O6-methylguanine-DNA methyltransferase (MGMT) mRNA expression has been investigated at the individual cell level in the liver of rats treated with dimethylnitrosamine using in situ hybridization. Male BDIV rats were orally administered with a single dose of dimethylnitrosamine (5 or 10 mg/kg) and were killed at 24, 48, and 96 hours after exposure. Constitutive MGMT mRNA expression was found in bile duct cells, vascular endothelial cells, and fibrous cells; however, weak or negative expression was detected in hepatocytes and Kupffer cells. On the other hand, after exposure to dimethylnitrosamine, inducible MGMT mRNA was rapidly expressed in hepatocytes, especially in the centrilobular area at earlier time points, confirming our previous studies in which enzymatic activity has been measured in different purified cell populations obtained by differential centrifugation. Immunohistochemical detection of the O6-methylguanine-DNA adduct formation was demonstrated in a dose-dependent fashion and was mainly found in the centrilobular hepatocytes where high levels of MGMT mRNA were present. These results suggest a correlation between the induction of this repair activity and DNA damage; however, the relationship between MGMT mRNA and enzyme activity remains to be fully established for all cell types.

Administration, Oral↗
PubMed1996

Evaluating asthma patient inhaler technique.

People with asthma need to be shown correct inhaler technique at initial diagnosis. Doctors, nurses and pharmacists are in a good position to demonstrate inhaler technique and make regular checks. Information and counselling for people with asthma would be helpful.

Asthma↗
PubMed1996

The challenge of health outcomes.

The health outcomes initiative can be seen as another passing phase in health-care management or taken as a serious challenge to the planning, management and evaluation of health services. This paper explores those challenges. Implementation of the health outcomes initiative will require the application of valid, reliable and appropriately sensitive measures, the use of a broad approach to research, development and monitoring in such a way that it is an intrinsic part of service delivery, the adoption of policy and practice that is firmly based on evidence of outcomes, and the development of an approach to research that emphasises generalizability.

Australia↗
PubMed1996

Molecular epidemiology of skin cancers: DNA repair and non-melanocytic skin cancer.

Exposure to sunlight has been clearly associated with non-melanocytic skin cancer, however individual susceptibility differs considerably. Ethnic origin and pigmentary characteristics are generally accepted as risk factors. Another important defense mechanism is the ability to repair DNA photoproducts. In the inherited disorder xeroderma pigmentosum the inability to repair such DNA damage, associated with a high incidence of skin cancers, suggests an important role for DNA repair capacity in the etiology of this cancer. The development of an in vitro repair assay based on human peripheral blood lymphocytes, has allowed the evaluation of DNA repair capacity as a risk factor in population based studies. This article reviews recent developments in this field.

Animals↗