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Biomedical subjects

A Bennett

Publications and source records attributed to A Bennett.

At least 55 records · Page 3Linked to original sources
PubMed1999

Boron stimulates yeast (Saccharomyces cerevisiae) growth.

Boron is required for the growth of vascular plants and embryonic development in fish. The molecular basis of boron's essentiality, however, remains unknown for both. The objective of this study was to determine whether yeast (Saccharomyces cerevisiae) could be used as a model for the evaluation of intracellular boron trafficking. Three experiments were conducted to assess the effect of boron supplementation on yeast growth. Cultures were grown in low boron media containing 0.04 micromol B/L. After 24 h, a new flask was inoculated with this culture; it was allowed to reach early log phase growth (9 h) and was then divided between two flasks. One flask was supplemented with ultrapure boric acid to achieve a concentration of 185 micromol B/L (+B); the other was supplemented with an equivalent volume of ultrapure water (NB). Boron significantly stimulated cell growth rate into the stationary phase of growth. Yeast cell boron concentrations decreased in both treatments over the course of the experiment, but analysis by inductively coupled plasma-mass spectrometry (ICPMS) did not detect differences in cellular concentration between the boron supplemented (B) and nonsupplemented (NB) groups. Ethanol concentrations did not differ between the two treatments, demonstrating that boron-stimulated growth was not a secondary effect of alcohol dehydrogenase inhibition. The demonstration of boron-dependent growth stimulation in yeast suggests that Saccharomyces cerevisiae can be used as a model system for the study of intracellular boron trafficking.

Boron↗
PubMed1998

Interactive effects of subanesthetic ketamine and subhypnotic lorazepam in humans.

Ketamine is an N-methyl-D-aspartate (NMDA) receptor antagonist with psychotogenic and dissociative effects in healthy humans. These cognitive and perceptual effects in humans are reportedly reduced by benzodiazepine premedication. This study assessed the interactive effects of a ketamine (i.v. bolus of 0.26 mg/kg followed by an infusion of 0.65 mg/kg per hour) and lorazepam 2 mg., PO, in humans. Twenty-three healthy subjects completed 4 test days involving the oral administration of lorazepam or matched placebo 2 h prior to the i.v. infusion of ketamine or placebo. Ketamine: 1) produced behaviors similar to the positive and negative symptoms of schizophrenia as assessed by the Brief Psychiatric Rating Scale (BPRS); 2) evoked perceptual alterations as measured by the Clinician-Administered Dissociative States Scale (CADSS); 3) impaired performance on the Wisconsin Card Sorting Test (WCST) and other tests sensitive to frontal cortical impairment; and 4) had amnestic effects. Lorazepam produced attention impairments, concrete proverb interpretations, and recall impairments. Lorazepam reduced ketamine-associated emotional distress and there was a non-significant trend for it to decrease perceptual alterations produced by ketamine. However, it failed to reduce many cognitive and behavioral effects of ketamine, including psychosis. Further, lorazepam exacerbated the sedative, attention-impairing, and amnestic effects of ketamine. There was no evidence of pharmacokinetic interaction between these medications. These data suggest that subhypnotic lorazepam and ketamine show a spectrum of interactive effects, ranging from antagonism to potentiation.

Adult↗
PubMed1998

Patients with primary osteoarthritis show no change with ageing in the number of osteogenic precursors.

The variation in marrow colony forming unit-fibroblastic (CFU-F) number in 59 patients (14-87 years of age) undergoing corrective surgery (14 controls; 14-48 years of age) or hip arthroplasty for primary osteoarthritis (45 OA; 46-87 years of age) was examined to determine whether marrow CFU-F, derived from marrow stromal fibroblastic stem cells, are maintained with the development of primary osteoarthritis (OA). Total colony number, colony size as well as alkaline phosphatase-positive colonies were determined. The mean fibroblast colony forming efficiency from the whole patient group was 2.4 x 10(-5) +/- 1.4 x 10(-5). Ageing had no effect on the colony forming efficiency or on the alkaline-phosphatase-positive colony forming efficiency, irrespective of gender. Thus precursor cells with the potential for osteogenic differentiation are maintained in OA with ageing. However, colony size showed a significant reduction with age, implying altered proliferation potential of osteogenic progenitors with ageing. This ageing effect may not be as significant in OA as in the rest of the population as bone mineral density is often preserved in osteoarthritis. As there is no apparent deficit in primitive progenitor cells, this preservation may be the result of altered regulation of osteoprogenitor activity in OA.

Adolescent↗
PubMed1998

Genetic and environmental factors affecting bone mineral density in large families.

This study assessed whether relatives with low bone mineral density (BMD) could be identified in five large families using historical, biochemical, and genetic markers for osteoporosis. Fifty of 65 relatives had their bone density and bone turnover markers measured, together with an assessment of their risk factors for osteoporosis. Only 33% (5/15) of siblings, 50% (6/12) of children and 43% (10/23) of nephews and nieces had entirely normal BMD. There was no difference in life-style risk factors for osteoporosis, history of previous fractures or body mass index between normal subjects and those with osteopenia or osteoporosis. Osteopenic individuals had a significantly higher than normal osteocalcin value. Within families, there was no clear association between BMD and any of the genetic markers (vitamin D receptor gene polymorphisms, COL 1A1 and COL 1A2 polymorphisms of the collagen gene), either alone or in combination. The addition of genetic markers to the other risk factors for low BMD did not improve the prediction of BMD. In conclusion, we suggest that the presence of osteoporosis in a first degree relative should be one of the clinical indications for bone density measurement as the individuals at risk would not be picked up by other methods.

Adult↗
PubMed1998

HIV risk behavioral surveillance: a methodology for monitoring behavioral trends.

OBJECTIVE: This article summarizes issues and recommendations for conducting HIV risk behavioral surveillance surveys (BSS) based on experiences from ten BSS projects in eight countries in Asia and Africa. BACKGROUND: BSS consists of systematic and repeated cross-sectional surveys of HIV and sexually transmitted disease-related behaviors, with other knowledge and attitudinal variables added where appropriate. Its major purpose and utility is in detecting trends among selected vulnerable and high-risk population groups whose behavioral change can have the most impact on the epidemic. BSS is also useful for tracking trends in behaviors over time in regions exposed to HIV prevention activities, as a contributing component to the comprehensive monitoring and evaluation of interventions. RECOMMENDATIONS: (i) implement BSS as an essential adjunct to HIV/STD epidemiological surveillance; (ii) use BSS for evaluation purposes in combination with process data and triangulate results with qualitative research; (iii) choose sentinel groups based on epidemiological considerations, evaluation and monitoring needs, representative sampling frames, and political and cultural considerations; (iv) maintain 1-year intervals between survey waves for most groups in order to provide yearly updates on behavioral trends for programmatic adjustments; (v) use internationally standardized indicators and question wording; (vi) maintain strict quality control standards to enhance data validity and reliability; and (vii) develop a clear dissemination strategy during BSS design to increase the likelihood of utilization of BSS results. CONCLUSION: BSS represents a cost-effective way to determine whether programmatic behavioral targets and goals are being met, to identify persisting risk behaviors over time, and to indicate whether new intervention approaches are necessary.

Africa↗
PubMed1997

Apolipoprotein E epsilon4 associated with chronic traumatic brain injury in boxing.

CONTEXT: Given the similarities between Alzheimer disease and dementia pugilistica, we evaluated the relationship between apolipoprotein E (APOE) genotype and chronic traumatic brain injury (CTBI) in boxers to determine whether there is a genetic susceptibility to the effects of head trauma. OBJECTIVE: To assess the relationship between CTBI and APOE genotype in boxers. DESIGN AND SETTING: Clinical characterization of 24 volunteer and 6 referred boxers in an outpatient setting. PARTICIPANTS: Thirty professional boxers aged 23 to 76 years underwent neurologic and behavioral assessment in conjunction with APOE genotyping. MAIN OUTCOME MEASURES: Apolipoprotein E genotype was examined in relationship to measures of CTBI. A 10-point clinical rating scale (0-9), the Chronic Brain Injury (CBI) scale, was devised to assess the severity of traumatic encephalopathy associated with boxing. Boxers with abnormal CTBI scores were further classified on the basis of whether their impairments were possibly or probably related to boxing. Scores were analyzed in relation to boxing exposure (number of bouts) and APOE genotype. RESULTS: Among the 30 boxers, 11 were found to be normal (CBI score=0), 12 showed mild deficits (CBI score=1-2), 4 were moderately impaired (CBI score=3-4), and 3 showed signs of severe impairment (CBI score > 4). High-exposure boxers (ie, those with > or = 12 professional bouts) had significantly higher CBI scores (mean [SD], 2.6 [1.9]) than low-exposure boxers (mean [SD], 0.3 [0.7]) (P<.001), indicating that neurologic impairment as measured by the CBI scale seems related to boxing exposure. The APOE genotype frequencies of the study population were approximately the same as those found in the general population. Boxers with low exposure had mean CBI scores of 0.33, irrespective of APOE genotype. However, high-exposure boxers with an APOE epsilon4 allele had significantly greater CBI scores (mean [SD], 3.9 [2.3]) than high-exposure boxers without APOE epsilon4 (mean [SD], 1.8 [1.2]) (P=.04). All boxers with severe impairment possessed at least 1 APOE epsilon4 allele. The tendency for greater CTBI among those with both high exposure and an epsilon4 allele was statistically significant at the P<.001 level. CONCLUSIONS: These preliminary findings suggest that possession of an APOE epsilon4 allele may be associated with increased severity of chronic neurologic deficits in high-exposure boxers.

Adult↗
PubMed1997

Safe biotechnology. 8. Transport of infectious and biological materials. Working Party "Safety in Biotechnology" of the European Federation of Biotechnology.

The transport of infectious and biological material is regulated by a number of international organizations. This mini-review has been compiled to increase awareness within the scientific community of problems caused by differences in terminology (such as infectious materials/substances, biological products, diagnostic specimens, genetically modified microorganisms) and certain technical aspects of the main international guidelines, and to assist policy makers in the creation of harmonized guidelines. A list of relevant Internet resources has been compiled.

Animals↗
PubMed1997

Cytosolic phospholipase A2, cyclo-oxygenases and arachidonate in human stomach tumours.

Human stomach tumours usually form more prostaglandins (PGs) than their associated normal mucosa/submucosa, but the mechanisms are not fully understood. The key enzymes are cytosolic phospholipase A2 (cPLA2, Mr 85,000) and the cyclo-oxygenases (COXs) which exist in constitutive (COX-1) and inducible forms (COX-2). In human stomach tumours and associated macroscopically normal tissues, we determined the fatty acid composition by gas chromatography, amounts of cPLA2, COX-1 and COX-2 by immunoblotting with specific antibodies and cPLA2 enzyme activity using a tritiated substrate. Although compared to normal mucosa there was less arachidonate in tumours (P < 0.05), the arachidonate/total fatty acid ratio was higher. Mean amounts of cPLA2 and COX-1 and cPLA2 activity were similar in tumours and normal mucosa. However, substantial amounts of COX-2 were found in the tumours but not in the mucosa, which may explain why many gastric tumours form increased amounts of PGs.

Aged↗
PubMed1997

Identification and enrichment of human osteoprogenitor cells by using differentiation stage-specific monoclonal antibodies.

A major problem in developmental bone biology is the inability to clearly identify early progenitor cells of the osteogenic and related lineages. Identification of these cells is important for the study of their normal development and for determination of potential changes in skeletal diseases. The objective of the present study was to obtain specific markers for early progenitor cells. Monoclonal antibodies were raised against human marrow stromal fibroblastic cell cultures, known to be rich in progenitors for the stromal lineages. Antibodies were selected initially by their reactivity with these marrow cultures and their immunohistochemical localization in human fetal tissues, in progenitor cell regions adjacent to osteoblastic cells. Antibody HOP-26 was strongly reactive with cells in marrow stromal colonies at early stages of differentiation, before the induction of alkaline phosphatase activity, and decreased dramatically after the cells reached confluence. In sections of human fetal limb, binding of HOP-26 was restricted to cells in close proximity to the developing bone, in periosteum, and between the developing bone trabeculae. In adult trabecular bone tissue, HOP-26 was reactive with occasional cells present within the marrow spaces with osteoblasts, adipocytes, and fibrous tissue unreactive. No antibody binding was detected in sections of skin, muscle, appendix, brain, tonsil, or liposarcoma, or cultured SaOS II, MG63, or skin cells. In primary cell suspensions, HOP-26 was unreactive with blood cells but strongly reactive with 0.59 +/- 0.27% of nucleated marrow cells. The antigen associated with these cells was detectable both intracellularly and on the cell surface, and by using immunopanning, HOP-26 selected the marrow stromal fibroblastic colony-forming units (CFU-F). HOP-26 provides the means to identify osteogenic progenitor cells directly and with high specificity. The present studies demonstrate the value of this antibody in providing enriched populations of progenitor cells for experimental studies of osteogenic differentiation and in histopathology.

Alkaline Phosphatase↗
PubMed1997

The use of monoclonal gene rearrangement for detection of minimal residual disease in acute lymphoblastic leukemia of childhood.

Sensitive quantification of minimal residual disease (MRD) using the polymerase chain reaction (PCR) is strongly predictive of outcome in childhood acute lymphoblastic leukemia (ALL), with MRD levels at the end of induction therapy of >10(-3) predicting a poor outcome. Methods for sensitive quantification are, however, complicated and time-consuming. Detection by PCR of monoclonal immunoglobulin heavy chain (IgH) and T cell receptor (TCR) gene rearrangements is simple and can be used in routine laboratories but is non-quantitative and of lower but uncertain sensitivity. The aim of this study was to determine the value of detection of monoclonality in identification of different levels of MRD. We looked for monoclonality in 64 bone marrow aspirates which had been obtained from 31 patients with B lineage ALL at various times during induction therapy and for which levels of MRD had been determined by limiting dilution analysis using patient-specific PCR primers. Detection of monoclonality identified levels of MRD of > or =10(-3) during induction with a sensitivity of 78% and a specificity of 93%. The positive and negative predictive values were 0.86 and 0.88, respectively. The sensitivity of detection of a monoclonal IgH rearrangement was greater than that for the TCRgamma locus during induction as an IgH rearrangement was detected more often than a TCRgamma rearrangement in patients who had both IgH and TCRgamma rearrangement at diagnosis. Detection of monoclonality is therefore a simple and quick test applicable to the majority of patients with ALL and it may be useful in identifying high-risk patients at the end of induction and in identifying relapsing patients later during therapy.

Child↗
PubMed1997

Comparison of SSCP analysis and CFLP analysis for mutation detection in the human iduronate 2-sulfatase gene.

Scanning methodologies are used for the identification of DNA fragments that differ from the normal nucleotide sequence. Fragments that produce abnormal band patterns are sequenced for characterization of the exact mutation. Factors considered in choosing a scanning methodology include reproducibility, sensitivity, and time. In the present study, we compared single-stranded conformational polymorphism (SSCP) and Cleavase fragment length polymorphism (CFLP) methodologies for mutation scanning of exon VIII in the iduronate 2-sulfatase (IDS) gene. Mutations of the IDS gene result in an X-linked lysosomal storage disease, Hunter syndrome. These six known mutations analyzed by the two methods included a one base pair deletion, a one base pair insertion, and four point mutations. SSCP analysis detected all of the mutations and CFLP analysis detected three of the six mutations. We concluded that SSCP analysis was preferable to CFLP analysis for scanning exon VIII in the IDS gene for mutations.

Base Sequence↗