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Biomedical subjects

L Davidson

Publications and source records attributed to L Davidson.

At least 91 records · Page 5Linked to original sources

Effective treatment for acute alkali injury to the esophagus using weak-acid neutralization therapy: an ex-vivo study.

OBJECTIVE: 1) To evaluate whether neutralization therapy with weak acid is effective in reducing observed histopathologic esophageal tissue injury secondary to liquid alkali, 2) to quantify the temperature change of the neutralizing agent, and 3) to determine the effect of interval to therapy on injury severity. METHODS: Harvested Sprague-Dawley rat esophagi were catheterized and placed in an oxygenated saline bath (37 degrees C) for 60 minutes and then fixed in 10% formalin. Nine groups (n = 10) were perfused with 50% sodium hydroxide (NaOH). Six of the groups were treated by neutralization with cooled orange juice (OJ) or cola that was maintained between 2 degrees C and 4 degrees C. This was performed at 0, 5, or 30 minutes after injury. In addition, two positive control groups were exposed to OJ or cola at time 0 and were not exposed to strong alkali. A third control group was exposed to strong alkali but was not administered any subsequent treatment. The temperature of the neutralizing agent was recorded prior to instillation and after exiting the esophagus. Blinded pathologic scoring of 0 (no injury) to 3 (severe) was recorded performed for six histopathologic categories: epithelial cell viability, cornified epithelial cell differentiation, granular cell differentiation, epithelial cell nuclei, muscle cells, and muscle cell nuclei. Comparisons were made among treatment times using the Kruskal-Wallis test and linear trend analysis. RESULTS: For each histopathologic category and each treatment mode, the Kruskal-Wallis test showed significant differences between the groups (p < 0.002) over time. Trend analyses showed more severe injury with delayed neutralization therapy (p < 0.05) for each treatment mode and histopathologic category. CONCLUSION: Early neutralization therapy with OJ or cola reduces acute esophageal alkali injury. Additional in-vivo study is needed before neutralization therapy is adopted for clinical use.

Acids↗

Histopathologic evaluation of the therapeutic efficacy of water and milk dilution for esophageal acid injury.

OBJECTIVE: To determine whether acid-induced injury to the esophagus is decreased by early dilutional therapy with water or milk. METHODS: A controlled in-vitro animal model for acid injury to the esophagus was carried out using esophagi harvested from 70 Sprague-Dawley rats of both sexes and weighing 250-350 g. One control and six experimental groups each containing ten esophagi were instilled with 1 mL of 0.5 normal solution of hydrogen chloride (N HCl). Dilution with water or milk was performed at 0, 5, or 30 minutes postinjury in the experimental groups. No dilution was performed with the control group. Specimens were maintained in an oxygenated saline bath for a 60-minute experimental period and then fixed in 10% formalin for histologic evaluation. Injury severity was rated by blinded histopathologic examination using scores of 0 (no injury), 1 (minor), 2 (moderate), and 3 (severe) for the histopathologic categories: cornified epithelial cells (CEs), granular cells (GCs), granular cell nuclei (GNs), and basal cells (BCs). Red blood cells were scored as positive or negative for lysis. RESULTS: The controls showed the most severe outcomes. Significant differences in injury occurred for all time periods and histopathologic categories, except for the GN/water and BC/milk histopathologic category/treatment groups. However, a linear trend analysis was significant for all histopathologic categories except BC. These analyses support decreased injury in the earlier treated groups. Injury severity was highest in the most superficial cell layer (CE). CONCLUSIONS: Emergency therapy with water or milk reduces acute acid injury to the esophagus. Earlier treatment is associated with decreased injury severity. This research supports the use of dilutional therapy with water or milk for acute acid injury to the esophagus.

Acids↗

CD40-deficient mice generated by recombination-activating gene-2-deficient blastocyst complementation.

To study the role of B-cell antigen CD40 in immune responses, mouse embryonic stem (ES) cells in which both copies of the gene encoding CD40 had been disrupted by homologous recombination were injected in RAG-2 (recombination-activating gene-2)-deficient blastocysts to generate chimeras in which all mature lymphocytes are derived from the CD40-deficient ES cells. T- and B-cell number and phenotype were normal in the CD40-/- chimeras. However, B cells failed to proliferate and undergo isotype switching in vitro in response to soluble CD40 ligand (sCD40L) with interleukin 4 (IL-4) but responded normally to lipopolysaccharide (LPS) with IL-4. CD40-/- chimeras completely failed to mount an antigen-specific antibody response or to develop germinal centers following immunization with the T cell-dependent (TD) antigen keyhole limpet hemocyanin. In contrast, CD40-/- mutant mice responded normally to the T cell-independent (TI) antigens, 2,4,6-trinitrophenyl (TNP)-LPS and TNP-Ficoll. The most noticeable alteration in the serum immunoglobulin levels of young (6-8 weeks old) CD40-/- animals was absence of IgE and severe decrease of IgG1 and IgG2a. These results confirm the essential role of CD40- CD40L interactions in the antibody response to TD antigens and in isotype switching.

Animals↗

The influence of exercise on the energy requirements of adult males in the UK.

Energy expenditure was measured over 10 d using the doubly-labelled water (DLW) and activity diary methods in summer and winter in subjects with 'light' occupations but leisure activities which ranged from 'non-active' to 'very active'. The basal metabolic rate (BMR) and the energy cost of activities were determined by indirect calorimetry. The Department of Health (1991) predicted BMR for the group (6.89 (SD 0.30) MJ/d; n 18) was not significantly different from the measured value (7.17 (SD 0.70) MJ/d; n 18). The range of DLW-derived expenditure values within the group was BMR x 1.41 to 2.41. The largest seasonal change within individuals was BMR x 0.5. The energy expenditure of the group as a whole was lower in winter (BMR x 1.88; SD 0.33; n 9) than summer (BMR x 2.01; SD 0.30; n 9) though the difference was not statistically significant. The average summer and winter DLW-derived expenditure was BMR x 1.96 (SD 0.31; n 17). The activity diary estimate of expenditure was BMR x 1.79 (SD 0.32; n 17). In a subset of the group who were representative of the most active 26% of all adult males in the UK, the DLW-derived expenditure was BMR x 2.08 (SD 0.24; n 11). This is higher than the highest Department of Health (1991) estimate of BMR x 1.6 for individuals in light occupations. The measured energy costs of low-intensity activities were similar to those presented in the Department of Health (1991) report but the value determined for running (BMR x 13.08; SD 2.4; n 6) was higher than the highest value in the report (BMR x 6 to 8). The results indicate that the recent Department of Health (1991) reference values for energy may underestimate the expenditure of a significant proportion of the UK population largely because the energy costs of activity used in the report to calculate expenditure do not accurately reflect those achieved during active leisure in individuals who take regular exercise.

Adult↗

Sequence of ornithine decarboxylase from Lactobacillus sp. strain 30a.

A gene encoding biodegradative ornithine decarboxylase from Lactobacillus sp. strain 30a was isolated from a genomic DNA library and sequenced. Primer extension analysis revealed two transcription initiation sites. The deduced amino acid sequence is compared with the amino acid sequences of five previously reported bacterial decarboxylases, and conserved pyridoxal phosphate motif residues are identified.

Amino Acid Sequence↗

Defining managed care in public-sector psychiatry.

Although managed care is an established force in the private sector, there is growing interest and experimentation with this concept in the public sector. This interest has been generated by the increased demand for services, the shrinking resource base due to cutbacks in state budgets, and the fragmentation of care that has accompanied the shift from a centralized, hospital-based model to a decentralized, community-based model for treating individuals with serious mental illness. But despite this interest, no consensus exists about the form or functions of managed care in the public arena. Simply importing private-sector versions of managed care is inadequate given the substantial differences in the patient population and service delivery mechanisms. The authors present a functional analysis of managed care in the public sector. Drawing on their conceptualization of managed care, they outline a functional approach to evaluating the strengths and weaknesses of treatment systems, innovations such as privatization and capitation, and recent health care reform proposals.

Community Mental Health Services↗

Diet and oxidative stress in breast, colon and prostate cancer patients: a case-control study.

OBJECTIVE: To study the changes in pro-oxidant-antioxidant status in breast, colon and prostate cancer patients as compared to respective controls. DESIGN: Cross-sectional case-control study. The pro-oxidant status was measured by analysing alkanes (ethane and pentane) in exhaled air and lipid peroxidation (as malonaldehyde) in blood samples. The antioxidant capacity was measured by studying blood glutathione concentration, vitamin concentrations and serum antioxidant capacity in liposomes in vitro. SETTING: Aberdeen hospitals. SUBJECTS: Breast, prostate and colon cancer cases, and age- and sex-matched control patients (hospitalized for a benign disease). Breast cancer patients were females, prostate cancer patients were males and colon cancer patients were both males and females. Controls were age-matched to within 5 years, sex-matched and matched for smoking habits. RESULTS: The dietary study suggested a higher monoene and polyene fat intake in prostate cancer than in controls while in other cancer patients no significant differences were found. Breast and colon cancer patients tended to have lower vitamin intakes than controls. Pentane concentration in exhaled air increased in breast cancer patients as compared to respective controls. In serum total antioxidant capacity no significant differences were found. Both breast and colon cancer patients showed decreased C18:2 and C20:4 fatty acid concentrations in red blood cells while C22:6 concentration was elevated in breast cancer patients. CONCLUSIONS: Oxidative stress may be associated with malignant diseases, suggesting the importance of simultaneous analysis of pro- and antioxidation in the search of mechanistic parameters leading to the tumour formation.

Adult↗

The evolution of mental health services: partial hospitalization as a case example.

Controversy exists regarding the current status, merits, and future of partial hospitalization. Originally conceptualized as one of the least restrictive modalities for treating acutely ill or highly impaired individuals in the community, these functions increasingly are being addressed by rehabilitation programs and assertive or intensive outpatient treatments. At the same time, third-party payers, such as managed-care firms, are extending coverage for the partial-hospital modality. We use the current debates about the merits of this modality to identify potential forces that impede and promote the evolution of mental health services. Specifically, we use this case example to illustrate four prevailing myths about the manner in which services evolve.

Day Care, Medical↗

Gender differences in hepatic induction and inhibition of theophylline pharmacokinetics and metabolism.

This investigation examined whether or not a gender-related effect on theophylline pharmacokinetics and metabolism exists in smoking and nonsmoking subjects with and without the concurrent administration of cimetidine. With a crossover design, 28 healthy men and premenopausal women (14 in each group) were administered intravenous aminophylline before (phase 1) and during (phase 2) a 10-day course of cimetidine, 300 mg four times a day. Statistically significant gender- and smoking-related effects were seen for theophylline half-life and clearance in phase 1, but only the smoking effect was statistically significant for these pharmacokinetic parameters in phase 2. Urinary metabolite excretion patterns demonstrated a greater percentage of excretion of 3-methylxanthine in female smokers than in male smokers in phase 1. Time-averaged urinary clearance of 1,3-dimethyluric acid was greater in female smokers than in male smokers. In phase 2, a significant reduction in the clearance of 1,3-dimethyluric acid was noted in female smokers but not in any other group. The results of our investigation suggest that a significant difference in the pharmacokinetics of theophylline exists that is related to gender and smoking status. Theophylline metabolism also seems to vary according to these factors. Administration of cimetidine results in a significant reduction in clearance of theophylline and abolishes the gender differences but not the smoking differences.

Adult↗

Amino acid sequence of the coelomic C globin from the sea cucumber Caudina (Molpadia) arenicola.

The sequence of a globin from a marine invertebrate, the sea cucumber Caudina (Molpadia) arenicola (Echinodermata), is reported. This globin, chain C, is one of four major globins found in coelomic red cells in this organism and is the second to be sequenced. Chain C consists of 157 residues, is amino-terminally acetylated, and has an extended amino-terminal region. This globin shares a 60% sequence identity with the other sequenced C. arenicola globin, D chain (Mauri et al., Biochem. Biophys. Acta 1078, 63-67, 1991), but has a 93.6% identity with a globin from another sea cucumber, Paracaudina chilensis (Suzuki, Biochem. Biophys. Acta, 998, 292-296, 1989).

Amino Acid Sequence↗

Epidemiology of pediatric trauma: importance of population-based statistics.

To determine the validity of using hospital-based pediatric trauma registry data to draw specific inferences with regard to regional pediatric trauma system design, we compared statistical data on the incidence and mortality of pediatric and adult injuries and burns calculated by the New York State Department of Health, based on legally mandated reports of injury deaths and hospital discharges for 1989. During this year, some 488 children, aged 0 to 14 years, died as a result of injuries, a rate of 13.8 per 100,000 annually, of whom 408 (11.6/100,000) died as a result of traumatic injuries or burns, a population-based rate 20% of that observed in adults. During the same period, 16,402 children were hospitalized for treatment of traumatic injuries and burns, a rate of 465 per 100,000 annually, a population-based rate 56% of that observed in adults; and of this number, some 90 children died, yielding an in-hospital mortality "rate" (ie, case fatality ratio) of 0.55%, and a population-based rate of 2.6 per 100,000 annually. Thus, 9.0 of the 11.6 per 100,000 children who died in New York State in 1989 as a result of traumatic injuries and burns were not admitted to the hospital and, therefore, were unknown to the statewide hospital reporting system.(ABSTRACT TRUNCATED AT 250 WORDS)

Accidents, Traffic↗

Identification of childhood disability in Jamaica: the ten question screen.

This is the first in a series of papers that report the testing of two instruments for the identification and assessment of childhood disability by community workers (CWs) in Third World countries. It is part of the International Epidemiologic Study on Childhood Disability. The Ten Question Screen (TQ) was used as the main instrument to identify disability in a two stage population-based survey of 5478 children aged 2-9 years in Clarendon, Jamaica. In the second stage, TQ positive and 8% of the screen negative controls were professionally assessed by a doctor and a psychologist using standard criteria based on the main classification system of the ICIDH. Sensitivity of the TQ as a whole varied in different strata of the group and amongst different disabilities, from perfect in girls under 6 years, fits and motor disabilities and for serious disability in all group except boys over 5 years with cognitive disability. Specificity was good but the false positive rate was unacceptably high at 74%. It was concluded, firstly, that the validation of a simple questionnaire of perceptions of behaviour against objective measurements of impairments was perhaps not fair to the TQ. In spite of this, the TQ would be a very useful instrument in collecting disability data or for identifying people in need of rehabilitation help, if a way of reducing false positives could be found.

Child↗

Sense of self in recovery from severe mental illness.

This report based on research interviews conducted with persons struggling to recover from prolonged psychiatric disorders suggests that the rediscovery and reconstruction of an enduring sense of the self as an active and responsible agent provides an important aspect of improvement. This process of developing a functional sense of self in the midst of persisting psychotic symptoms and dysfunction is described, and its implications for understanding severe mental illness and processes of change are discussed. It is suggested that viewing the development of a dynamic sense of self as central to the improvement process provides a coherent thread which ties together diverse research findings concerning factors influencing course and outcome of illness. It is also suggested that for treatment and rehabilitation to elicit and foster a more functional sense of self, models of improvement will need to allow for, and encourage, a more active and collaborative role for the person with the disorder.

Activities of Daily Living↗

The promise of partial hospitalization: a reassessment.

In this review of trends in partial hospitalization since 1987, the authors provide a brief overview of the field, summarize recent research findings, examine the data on the growth of partial hospitals, and outline recent changes in public- and private-sector use of this treatment modality. Support for intermediate and long-term partial hospitalization is diminishing rapidly, while support for short-term partial hospitalization as an alternative to inpatient care is increasing in the private sector and diminishing in the public sector. The future for partial hospitals seems uncertain, as the treatment functions of these programs are being assumed by psychosocial and vocational rehabilitation programs and assertive community treatment teams. In light of these trends, the authors recommend new directions for partial hospital research involving comparisons between short-term day hospitalization and intensive outpatient interventions.

Cost Control↗