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Biomedical subjects

G Hall

Publications and source records attributed to G Hall.

At least 91 records · Page 5Linked to original sources
PubMed1997

Nucleus accumbens lesions impair context, but not cue, conditioning in rats.

Previous work has provided evidence of a role for the hippocampal formation in contextual as opposed to cue conditioning. Similar deficits have been observed after transection of the fimbria/fornix, part of which consists of the hippocampal-nucleus accumbens (N.Acc) connection arising from both the dorsal and ventral subiculum. By means of electrolytic lesions of the N.Acc, we showed that the subiculo-accumbens projection appears to participate in aversive conditioning to context, but not to a cue (tone). Freezing, measured as an index of learning, in the experimental context was greatly reduced in animals with lesions of the N.Acc, as compared with sham-operated controls. No difference was found in freezing to a distinct tone. These data lend further support to the notion that the N.Acc is an important interface between limbic structures and motor output.

Acoustic Stimulation↗
PubMed1997

Anti-major histocompatibility complex antibody responses to simian B cells do not protect macaques against SIVmac infection.

Macaques have been protected against infection with human cell-grown SIVmac by immunization with antigens encoded by the human major histocompatibility complex (MHC). Here, we investigated the efficacy of alloimmunization with simian B cells expressing high levels of MHC class I and class II molecules to confer protection against systemic challenge with simian-grown SIVmac. Eight rhesus macaques were vaccinated with glutaraldehyde-fixed and beta-propiolactone-inactivated herpesvirus papio-transformed B cells. Four of the macaques received 5 doses, the others 10. Animals were challenged with rhesus macaque spleen-derived cell-free SIVmac. Allogeneic B cells elicited antibody responses to rhesus MHC class I and II but failed to protect animals against infection. Anti-MHC class I antibodies were restricted in specificity and failed to recognize MHC class I from some B lymphoblastoid cell lines (B-LCLs) including a B-LCL from the animal in whose cells the challenge virus was grown. Vaccinated animals responded to self-MHC class I antigens but not to self-MHC class II antigens from peripheral blood mononuclear cells (PBMCs). Animals that underwent the shorter immunization regimen had transiently enhanced PBMC-associated virus loads after challenge, whereas the average virus-infected cell load was reduced in animals that underwent the more extensive immunization. These results suggest that antibody responses to allogeneic MHC molecules do not protect against infection with immunodeficiency lentiviruses.

Adoptive Transfer↗
PubMed1997

Clinical and pathologic findings in Doberman pinschers with occult cardiomyopathy that died suddenly or developed congestive heart failure: 54 cases (1984-1991).

OBJECTIVE: To determine echocardiographic, electrocardiographic, and histologic abnormalities in Doberman Pinschers with occult cardiomyopathy that died suddenly and to compare findings with those of Doberman Pinschers with cardiomyopathy that died of congestive heart failure. DESIGN: Retrospective study. ANIMALS: 14 Doberman Pinschers with occult cardiomyopathy that died suddenly (group 1) and 40 Doberman Pinschers with cardiomyopathy and congestive heart failure (group 2). PROCEDURE: Serial echocardiography and continuous, ambulatory electrocardiographic (Holter) monitoring were performed. Hearts of dogs that died suddenly were examined histologically. RESULTS: Group-2 dogs died at a significantly older age than did group-1 dogs. All dogs had echocardiographic abnormalities, but changes were more severe in group-2 than in group-1 dogs. Ventricular tachyarrhythmias were documented in all dogs. Group-1 dogs were more likely to have episodes of sustained ventricular tachycardia than were group-2 dogs. Multifocal interstitial fibrosis and replacement of muscle fibers with collagen and fat were consistently observed in hearts from dogs that died suddenly. Ten group-1 dogs had received antiarrhythmic treatment prior to death. CLINICAL IMPLICATIONS: Occult cardiomyopathy can be identified by means of echocardiography and Holter monitoring in Doberman Pinschers. Doberman Pinschers with cardiomyopathy that had episodes of sustained (> 30 seconds) ventricular tachycardia were at risk of dying suddenly.

Animals↗
PubMed1997

[Ground water and health. Reflections based on analysis of water specimens from Hordaland and Vestfold].

Basically, Norway has an ample supply of water. The quality of Norwegian drinking water, however, is threatened, not the least because of pollution of surface water reservoirs. Ground water is better protected against pollution, and sub-surface water sources are being exploited more than before. At present, less than 15% of the Norwegian population uses ground water for household purposes, but the percentage is increasing rapidly Ground water is (normally) clean and has a good taste. A large number of elements can be traced in ground water; some of them in concentrations of significance for human health. The present paper reports elemental analyses of 150 water samples from ground water reservoirs in rock, collected in Vestfold (Eastern Norway) and Hordaland (Western Norway). Sixty-four elements were assessed using modern equipment such as ICP-MS. In most cases the chemical composition of the water was well within the limits set for good quality drinking water. For some of the elements one or more of the results exceeded the "highest acceptable concentrations" as defined by the Norwegian health authorities. This was the case for Al, As, Ba, Ca, Cd, F, Fe, Hg, K, Mg, Mn, Na, P, Pb, Rn and Zn. No drinking water standards have been established for Be, Mo, Th and U, which are of clear significance to the health. More research is needed to assess the relationship between drinking water chemistry and human health. The authors call for a systematic analysis of all Norwegian ground water wells, and emphasise the need for regular quality control, even of small, private water supplies.

Humans↗
PubMed1997

Glial lineages and myelination in the central nervous system.

Oligodendrocytes, derived from stem cell precursors which arise in subventricular zones of the developing central nervous system, have as their specialist role the synthesis and maintenance of myelin. Astrocytes contribute to the cellular architecture of the central nervous system and act as a source of growth factors and cytokines; microglia are bone-marrow derived macrophages which function as primary immunocompetent cells in the central nervous system. Myelination depends on the establishment of stable relationships between each differentiated oligodendrocyte and short segments of several neighbouring axons. There is growing evidence, especially from studies of glial cell implantation, that oligodendrocyte precursors persist in the adult nervous system and provide a limited capacity for the restoration of structure and function in myelinated pathways damaged by injury or disease.

Adult↗
PubMed1997

Stimulus preexposure, comparison, and changes in the associability of common stimulus features.

In four experiments, rats received preexposure either to both of two compound flavours (AX and BX), or to just one (BX). Experiment 1 demonstrated a perceptual learning effect, showing that, for animals given preexposure to both flavours, an aversion conditioned to AX generalized only poorly to BX. Subsequent experiments assessed the properties of the common feature, X. Experiment 3 showed that the two preexposure treatments did not differ in the extent to which they produced habituation of the neophobia evoked by X. Experiment 2 showed that conditioning to X proceeded more rapidly in subjects given preexposure to both AX and BX than in subjects preexposed to BX alone. In Experiment 4, a similar effect was found when the elements of the compounds were presented serially. It is concluded that the perceptual learning effect of Experiment 1 occurs in spite of the fact that preexposure to two stimuli tends to maintain the associability of their common elements.

Analysis of Variance↗
PubMed1997

Spontaneous resolution of rhodococcal pulmonary infection in a liver transplant recipient.

Pulmonary infection by Rhodococcus equi is characterized by indolent infection in an immunocompromised host with a propensity to form cavitary lesions. Mortality can be greater than 50%; treatment involves prolonged therapy with multiple antibiotics and, occasionally, surgical resection. Recurrence is common. We report a case of a liver transplant patient with a pulmonary nodule caused by R equi; the nodule followed a benign clinical course and resolved spontaneously. This case illustrates that the spectrum of disease caused by R equi is not fully appreciated and that significant pitfalls complicate the diagnosis and management of infection by this unusual and probably underrecognized pathogen.

Actinomycetales Infections↗
PubMed1997

Effects of prostaglandin treatment and paracervical blockade on postoperative pain in patients undergoing first trimester abortion in general anesthesia.

BACKGROUND: The postoperative analgesic efficacy of a paracervical blockade (PCB) as an adjunct to general anesthesia (GA) during outpatient abortion (dilatation and curettage) is unclear, and the present study was initiated to evaluate if PCB is of significant importance per- or postoperatively. METHODS: Two hundred women (aged 18-49 years) were assigned to one of four groups; group 1 received vaginal prostaglandin (PG) (PGE1, gemeprost 1 mg) for softening of the cervix preoperatively and surgery was performed in GA, group 2 received preoperative PG and surgery was performed in GA + PCB; group 3 did not receive PG treatment and surgery was performed in GA and group 4 were subjected to GA + PCB without preoperative PG. RESULTS: Women receiving preoperative prostaglandin treatment (groups 1 and 2) reported significantly higher pain intensity already preoperatively, but also postoperatively as compared to patients not treated with PG. The patients subjected to prostaglandin treatment (groups 1 and 2) also had a significantly higher consumption of analgesics as compared to non-PG treated groups (3 and 4). The addition of PCB did not influence pre- and postoperative pain intensity significantly or consumption of analgesics. Patients receiving PG also reported significantly more nausea than the others although nausea was of low intensity. Patients receiving PG were, however, discharged earlier than the others from the hospital. CONCLUSIONS: Preoperative treatment of the cervix with prostaglandins was associated with significantly higher pain intensity both pre- and postoperatively, and increased need for analgesics postoperatively and more intense nausea. PCB given just before surgery did not result in significant postoperative analgesia. More efficient techniques for pain control should be developed for women subjected to first trimester abortion with preoperative PG treatment.

Abortion, Induced↗
PubMed1996

Effects of prophylactic administration of cefaclor on transient bacteremia after dental extraction.

This study was undertaken to investigate the effects of prophylactic administration of cefaclor on bacteremia after dental extraction. Thirty-nine patients were randomly assigned to receive either 1 g cefaclor (19 patients) or placebo (20 patients) 1 h prior to dental extraction. Blood samples for microbiological investigation were collected before, during, and 10 min after surgery, and were processed by lysis filtration under anaerobic conditions. The incidence of bacteremia with viridans streptococci was 79% in the cefaclor group and 50% in the placebo group during extraction. No difference in the incidence or magnitude of bacteremia was observed when the two patient groups were compared.

Adult↗
PubMed1996

Fatigue after major joint arthroplasty: relationship to preoperative fatigue and postoperative emotional state.

Fatigue has been widely assumed to increase after major surgery, and possible physical explanations have been intensively investigated. Nevertheless, existing data are almost exclusively from abdominal surgery and are based on the use of a single visual analogue scale. Moreover, no physical basis has been found. The present study used a more homogeneous surgical model than has been employed hitherto in order to find whether fatigue was related to emotional state. We measured fatigue before and 1 and 7 weeks after major joint arthroplasty in 63 patients, using a questionnaire that separates mental and physical fatigue. Physical function and subjective emotional and somatic state were measured at the same times; optimism was measured preoperatively. Neither mental nor physical fatigue increased after this form of surgery. Mental and physical fatigue each correlated with low positive mood throughout. The best predictor of physical fatigue postoperatively and at follow-up was preoperative physical fatigue. Preoperative mental fatigue and negative mood were independent predictors of mental fatigue postoperatively and at follow-up. Preoperative fatigue also predicted worse subjective emotional and physical state after surgery. These results suggest that fatigue should be regarded as an aspect of emotional distress perioperatively and that complaints of fatigue postoperatively may reflect the tendency to complain of fatigue or negative mood preoperatively rather than being attributable to surgical trauma.

Aged↗
PubMed1996

Contextual control of conditioned responding in rats with dorsal hippocampal lesions.

The control exerted by contextual cues over classically conditioned responding was assessed for rats with electrolytic lesions of the dorsal hippocampus and sham-operated controls. In 3 experiments the rats received initial training with 2 reinforced cues, each presented in its own distinctive context, followed by a nonreinforced test in which the cues were presented in the other context. Both control and operated subjects showed context specificity, as evidenced by less vigorous responding to these cues than to cues presented on test in their original contexts. The groups did not differ in their ability to learn an explicit discrimination in which a given cue was reinforced in one context and nonreinforced in a different context (although the groups did differ on a simple autoshaping task). It is concluded that a special role for the hippocampus in the contextual control of conditioned responding still remains to be demonstrated.

Animals↗
PubMed1996

Protective mucosal immunity elicited by targeted iliac lymph node immunization with a subunit SIV envelope and core vaccine in macaques.

Prevention of sexually transmitted HIV infection was investigated in macaques by immunization with a recombinant SIV (simian immunodeficiency virus) envelope gp 120 and core p27 vaccine. In two independent series of experiments, we used the novel targeted iliac lymph node (TILN) route of immunization, aiming close to the iliac lymph nodes draining the genitorectal mucosa. Rectal challenge with the SIVmac 32H J5 molecular clone in two series induced total protection in four out of seven macaques immunized by TILN, compared with infection in 13 of 14 unimmunized macaques or immunized by other routes (P = 0.025). The remaining three macaques showed either a decrease in viral load ( > 90%) or transient viremia, indicating that all seven TILN-immunized macaques showed total or partial protection (P = 0.001). Protection was associated with significant increase in the iliac lymph nodes of IgA antibody-secreting cells to p27 (P < 0.02), CD8-suppressor factor (P < 0.01), and the chemokines RANTES and MIP-1 beta (P < 0.01).

Animals↗
PubMed1996

Positive diepoxybutane test in only one of two brothers found to be compound heterozygotes for Fanconi's anaemia complementation group C mutations.

Fanconi's anaemia (FA) is an autosomal recessive disorder characterized by diverse congenital abnormalities, the development of progressive bone marrow failure, and an increased predisposition to malignancy, particularly acute leukaemia. The FA phenotype is so variable that diagnosis on the basis of clinical manifestations alone can be difficult. The modern diagnosis of FA no longer rests entirely on the constellation of clinical and haematological abnormalities first described by Fanconi, but depends on finding elevated chromosomal breakage after incubation of peripheral blood lymphocytes with the chemical clastogens diepoxybutane (DEB) or mitomycin-C (MMC). The cloning of the gene for FA complementation group C [FAC] provides an opportunity to test the validity of the "DEB test' which in recent times has become the main arbiter as to whether a patient is classified as FA or non-FA. We report on two brothers with similar clinical and haematological features who have both been identified as compound heterozygotes for the FAC mutations L554P and delta G322, but only one of the brothers has a positive DEB test. On the basis of the DEB test one would be classified as FA and the other as non-FA. The time has come to re-evaluate the diagnostic criteria of "Fanconi's anaemia'.

Adolescent↗
PubMed1996

Elimination of bacteraemia after dental extraction: comparison of erythromycin and clindamycin for prophylaxis of infective endocarditis.

Erythromycin and clindamycin are currently recommended for antibiotic prophylaxis of infective endocarditis in predisposed patients allergic to penicillin undergoing oral invasive procedures. Thirty-eight healthy patients were randomized to receive either erythromycin (1 g) or clindamycin (0.6 g) orally 1.5 h prior to dental extraction. Blood samples for microbiological investigation were collected before, during and 10 min after surgery and were processed by lysis filtration under anaerobic conditions. The incidence of bacteraemia with viridans streptococci was 79% in the erythromycin group and 74% in the clindamycin group. No statistically significant difference was noted in incidence or magnitude of bacteraemia with viridans streptococci or anaerobic bacteria between the two groups, at any sampling time. Ninety-six aerobic and 133 anaerobic strains recovered from the blood samples were tested for their susceptibility to erythromycin and clindamycin as well as to penicillin V and ampicillin. The antimicrobials were found to be highly active against the majority of bacteria except for some enterococci, staphylococci and veillonella. Protection from endocarditis by prophylaxis with erythromycin or clindamycin must be due to elimination of bacteria at a later stage in the development of the disease, rather than by elimination of bacteria from blood during the short period of postoperative bacteraemia.

Adult↗
PubMed1996

High-level transgene expression in plant cells: effects of a strong scaffold attachment region from tobacco.

We have previously shown that yeast scaffold attachment regions (SARs) flanking a chimeric beta-glucuronidase (GUS) reporter gene increased per-copy expression levels by 24-fold in tobacco suspension cell lines stably transformed by microprojectile bombardment. In this study, we examined the effect of a DNA fragment originally identified in a tobacco genomic clone by its activity in an in vitro binding assay. The tobacco SAR has much greater scaffold binding affinity than does the yeast SAR, and tobacco cell lines stably transformed with constructs containing the tobacco SAR accumulated greater than fivefold more GUS enzyme activity than did lines transformed with the yeast SAR construct. Relative to the control construct, flanking the GUS gene with plant SARs increased overall expression per transgene copy by almost 140-fold. In transient expression assays, the same construct increased expression only approximately threefold relative to a control without SARs, indicating that the full SAR effect requires integration into chromosomal DNA. GUS activity in individual stable transformants was not simply proportional to transgene copy number, and the SAR effect was maximal in cell lines with fewer than approximately 10 transgene copies per tobacco genome. Lines with significantly higher copy numbers showed greatly greatly reduced expression relative to the low-copy-number lines. Our results indicate that strong SARs flanking a transgene greatly increases expression without eliminating variation between transformants. We propose that SARs dramatically reduce the severity or likelihood of homology-dependent gene silencing in cells with small numbers of transgenes but do not prevent silencing of transgenes present in many copies.

Amino Acid Oxidoreductases↗
PubMed1996

Shadowing on the basis of contextual information in individuals with schizotypal personality.

The Schizotypal Personality Questionnaire (SPQ; Raine, 1991) was administered to 100 volunteer undergraduates; the 20 with the highest and the 20 with the lowest scores were selected for further study. They undertook a shadowing task in which two passages of prose were presented simultaneously and binaurally, being distinguishable only by their content. Participants were required to repeat (shadow) one of the passages and to ignore the other (the distractor). Performance of the two groups differed with participants having high scores on the SPQ showing a significantly greater tendency to make intrusion errors (to repeat words from the distractor passage). It is suggested that schizotypy is characterized by a dysfunction in the normal response-selection mechanism of attention with the consequence that the response bias established by the semantic content of the input is insufficiently selective, extending to items that are only distantly associated with those present in the input.

Adult↗