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Biomedical subjects

W Howe

Publications and source records attributed to W Howe.

14 recordsLinked to original sources
PubMed2002

Terazosin for treating symptomatic benign prostatic obstruction: a systematic review of efficacy and adverse effects.

OBJECTIVE: To systematically review and evaluate the effectiveness and adverse effects of the alpha-antagonist, terazosin, for treating urinary symptoms associated with benign prostatic obstruction (BPO). METHODS: Studies were sought and included in the review if they were randomized trials of at least 1 month duration, involved men with symptomatic BPO and compared terazosin with placebo or active controls. The study, patient characteristics and outcome data were extracted in duplicate onto standardized forms using a prospectively developed protocol. RESULTS: Seventeen studies involving 5151 men met the inclusion criteria, i.e. placebo-controlled (10), alpha-blockers (seven), finasteride alone or combined with terazosin and placebo (one), and microwave therapy (one). The study duration was 4-52 weeks; the mean age of the men was 65 years and 82% were white. Baseline urological symptom scale scores and flow rates showed that men had moderate BPO. Efficacy outcomes were rarely reported in a way that allowed for data pooling, but indicated that terazosin improved symptom scores and flow rates more than did placebo or finasteride, and similarly to other alpha-antagonists. The pooled mean percentage improvement for the Boyarsky symptom score was 37% for terazosin and 15% for placebo (four studies). The mean percentage improvement for the American Urological Association symptom score was 38%, compared with 17% and 20% for placebo and finasteride, respectively (two studies). The pooled mean improvement in the International Prostate Symptom Score of 40% was similar to that with tamsulosin (43%). Peak urinary flow rates improved more with terazosin (22%) than with placebo (11%) and finasteride (15%), but did not differ significantly from the other alpha-antagonists. The percentage of men discontinuing terazosin was comparable with those receiving placebo and finasteride, but greater than with other alpha-antagonists. Adverse effects were greater than with placebo and included dizziness, asthenia, headache and postural hypotension. CONCLUSIONS: The available evidence indicates that terazosin improves the symptoms and flow rates associated with BPO; it was more effective than placebo or finasteride and similar to other alpha-antagonists. Adverse effects were generally mild but more frequent than with other alpha-antagonists and associated with a two- to four-fold increase in treatment discontinuation.

Adrenergic alpha-Antagonists↗
PubMed2001

Does gymnastics training inhibit growth of females?

OBJECTIVE: The increasingly dominant performance of smaller-sized female gymnasts and increased magnitude of training beginning at an early age have prompted public and medical concerns, especially from an auxological perspective. The objective of this review is to determine if gymnastics training inhibits growth of females. DATA SOURCES: An extensive research of MedLine (PubMed interface) along with cross-referencing was conducted using the Text and MeSH words "gymnastics" in combination with "growth," "maturation," "body height," "body weight," and "growth plate." Our analysis is limited to English articles only. STUDY SELECTION: All published studies that included data related to the research questions were included. MAIN RESULTS: Although data from three historical cohort studies indicate that female gymnasts are short even before they begin training, clinical reports and cohort studies do suggest that some female gymnasts experience attenuated growth during training followed by catch-up growth during periods of reduced training or retirement. There is conflicting evidence whether the "catch-up" is complete. There were no studies reporting prevalence or incidence of inadequate growth. Three cohort studies provide evidence of reduced growth but training was not partitioned from other confounding factors in the gymnastics environment. Although there is a paucity of studies examining the link of dietary practices with diminished growth in female gymnasts, a review of related dietary literature indicates the potential for insufficient energy and nutrient intake among female gymnasts. CONCLUSIONS: Elite level or heavily involved female gymnasts may experience attenuated growth during their years of training and competition followed by catch-up growth during reduced training schedules or the months following retirement. However, a cause-effect relation between gymnastics training and inadequate growth of females has not been demonstrated.

Adolescent↗
PubMed2001

Neurotrophin and neurotrophin receptor expression by cells of the human lamina cribrosa.

PURPOSE: To determine whether cells and tissue from the human lamina cribrosa (LC) express neurotrophin and tyrosine kinase (trk) receptor mRNA and protein and whether these cells secrete neurotrophins. METHODS: Synthesis of cDNA and the reverse transcription-polymerase chain reaction (RT-PCR) were conducted using total RNA obtained from well-characterized cell lines from the human LC and human optic nerve head (ONH) tissue. Immunofluorescent localization and Western blot analysis were used to evaluate neurotrophin and trk protein expression in cells and tissue from the human LC. Immunoassay systems (ELISAs) were used to detect the secretion of neurotrophins. RESULTS: Two morphologically distinct cell types (LC cells and ONH astrocytes) were isolated and characterized from the human LC. Messenger RNA for each of the neurotrophins, three full-length trk receptors and two truncated trk receptors were detected in both cell types and in human ONH tissue. Protein for the neurotrophins and trk receptors were detected in LC cells, ONH astrocytes, and ONH tissue. Neither cell type expressed mRNA or protein for the low-affinity neurotrophin receptor p75. The secretion of neurotrophins was observed in both cell types. CONCLUSIONS: Cells from the human LC express mRNA and protein of neurotrophins and trk receptors. In addition, cells from the LC secrete neurotrophins, which suggests that there is paracrine and/or autocrine signaling within the LC. Neurotrophin signaling within this region of the ONH may play important roles in the maintenance of the normal LC and in such diseases as glaucoma.

Blotting, Southern↗
PubMed1997

Does repetitive physical loading inhibit radial growth in female gymnasts?

OBJECTIVE: Stress-related injuries to the distal radius have been noted in female gymnasts with potential for resultant premature closure and abnormal growth at this site. The purpose of this study was comprehensively to review and critically to appraise the available literature to examine the evidence related to this question: does repetitive physical loading inhibit growth of the radius in female gymnasts? DATA SOURCES: MEDLINE and SPORT Discuss were searched from 1975 to the present by using "gymnast" in combination with injury, growth plate, epiphyseal, and ulnar variance. Additional references were retrieved from the bibliographies of the retrieved articles. STUDY SELECTION: All descriptive and analytic studies that included data related to stress-related injuries affecting the distal radius of competitive female gymnasts were included. Conclusions regarding the effects of gymnastics training on radial growth of female gymnasts were limited to data from case reports, clinical series, cross-sectional studies, and descriptive cohort studies. Data from relevant experimental animal studies also were included. DATA EXTRACTION AND SYNTHESIS: In reviewing the literature, particular attention was paid to the relative strengths of the different study designs. From these data, information associated with growth inhibition at the distal radius was examined. MAIN RESULTS: The descriptive research reviewed included clinical, cross-sectional, and cohort studies that establish the existence of stress-related injuries affecting one or more constituent parts of the epiphyseal-physeal-metaphyseal (EPM) complex of the distal radius, symptomatic ulna-radial-length difference (URLD), and distal radius physeal arrest among female gymnasts. Five cross-sectional studies showed radiographic abnormalities consistent with distal radius physeal-stress reaction in 10-85% of gymnasts studied. Two cross-sectional studies indicated "abnormal" positive URLD in 8-20% of wrists radiographed. Four cross-sectional studies showed significant correlations between training intensity and URLD, suggesting a dose-response relation. Three cross-sectional studies indicate greater URLD in gymnasts compared with nongymnasts. Radiographic evidence of distal radius physeal arrest involving physically immature female gymnasts is presented in four studies (two clinical series, one cross-sectional, and one descriptive cohort). In animal studies, prolonged physical training has also been shown to inhibit or stop growth in weight-bearing long bones. However, there were no rigorous studies (i.e., randomized control trials or analytic cohorts) examining the question. CONCLUSION: The results of this critical review of the scientific literature support the plausibility of stress-related distal radius physeal arrest with secondary URLD. However, the strength of evidence is inadequate to be conclusive.

Adolescent↗
PubMed1995

A systematic approach to health surveillance in the workplace.

This paper reviews the range of health surveillance activities which can be utilized in the workplace by occupational health professionals for assessing fitness for work and contributing to the prevention of occupational illness and promotion of good health. The systematic approach described categorizes health surveillance procedures into occupational or non-occupational, risk-based or unfocused, and as primary, secondary or tertiary preventive measures. All categories of health surveillance are currently being practised to some extent, but the type of surveillance may not match the needs of the workplace in some situation. In order to aid health professionals in deciding which procedures should be implemented, recommendations based on an assessment of health risks are made. The key proposal is to establish a minimum level of periodic health surveillance for all workers based on a targeted lifestyle health risk assessment and a structured health questionnaire. Additional procedures can then be added sequentially as appropriate to manage any health risks in the workplace. The role of the unfocused periodic general medical examination is discussed in the context of the systematic approach and allows occupational professionals to critically appraise its usefulness.

Health Promotion↗
PubMed1994

Glucocorticoid-induced formation of cross-linked actin networks in cultured human trabecular meshwork cells.

PURPOSE: To determine the effects of glucocorticoid treatment on the microfilament structure of cultured human trabecular meshwork cells. Topical or systemic administration of glucocorticoids can lead to the development of ocular hypertension and to the development of vision loss, which is clinically similar to primary open angle glaucoma. However, the mechanism(s) by which glucocorticoids cause ocular hypertension is not well defined. Alterations in the trabecular meshwork, the site of drainage of aqueous humor from the eye, have been linked to the development of ocular hypertension. METHODS: Human trabecular meshwork cells were cultured in the presence and absence of glucocorticoids for 0 to 21 days. The microfilament organization of the cultured trabecular meshwork cells was examined by epifluorescent and transmission electron microscopy. RESULTS: Glucocorticoids caused a progressive change in the organization of microfilaments in the trabecular meshwork cells, but not in other cultured ocular cells. By fluorescence microscopic analysis, the actin stress fibers found in control trabecular meshwork cells were reorganized on treatment with glucocorticoids into cross-linked actin networks that resembled geodesic-dome-like polygonal lattices. The cross-linked actin networks were reversible on withdrawal of the glucocorticoid treatment. Dose-response data for dexamethasone, relative ranking of activity with glucocorticoid potency, and partial inhibition with glucocorticoid antagonists all suggest the involvement of the trabecular meshwork glucocorticoid receptor in cross-linked actin network formation. The reorganization of the trabecular meshwork cytoskeleton alters cell function because glucocorticoid treatment of cultured trabecular meshwork cells also inhibited trabecular meshwork cell migration and proliferation. CONCLUSION: The steroid-induced alteration in trabecular meshwork cytoskeleton may be an important factor in the development of steroid-induced ocular hypertension and may play a role in the ocular hypertension associated with primary open angle glaucoma.

Actin Cytoskeleton↗
PubMed1990

Human inhalation pharmacokinetics of 1,1,2-trichloro-1,2,2-trifluoroethane (FC113).

Seven male volunteers were exposed to atmospheric concentrations of either 1980, 4100 or 7630 mg m-3 1,1,2-trichloro-1,2,2-trifluoroethane (FC113) for 4 h. Blood and expired air samples were collected during the exposure period and for several days subsequently and analysed for FC113. Blood and breath concentrations of FC113 were related to the administered dose with some variation between individuals. The low blood/breath ratios measured are consistent with the low solubility of FC113 in blood. The absorption and elimination of FC113 can be described by a three-compartment model and the average half-lives of elimination of FC113 in breath were 0.22, 2.3 and 29 h. A pulmonary retention during the exposure period of 14% was measured but only 2.6 to 4.3% of the dose was recovered unchanged in breath after the exposure period, suggesting that FC113 could be metabolised following inhalation exposure. It is concluded that a practical method for biological monitoring during occupational exposure would be to measure end-tidal breath concentrations of FC113 in samples taken the morning after exposure. The predictive value of such a measurement can be improved if the results are normalised to the body fat content of individual workers which can be estimated from height and weight measurements.

Administration, Inhalation↗
PubMed1987

Immunologic and functional consequences of chemical (tetrachlorophthalic anhydride)-induced asthma after four years of avoidance of exposure.

Seven patients with occupational asthma caused by a chemical, tetrachlorophthalic anhydride (TCPA), left their work in 1980. They have subsequently avoided TCPA exposure and have been followed until 1985. One patient died in 1981. The six living patients reported continuing symptoms suggestive of asthma, and five who were studied in 1985 demonstrated mild bronchial hyperresponsiveness (histamine concentration provoking a 20% fall in FEV1 range 2.7 to 12.5 mg/ml). Specific IgE antibody to TCPA conjugated with human serum albumin was measured by a radioallergosorbent test and detected in all patients. After avoidance of exposure, specific IgE fell exponentially with a half-life of 1 year. Specific IgE was still detectable in 1985, and throughout the follow-up period, prick tests with the conjugate elicited immediate skin responses. In 1981 four patients had inhalation tests with TCPA, and specific IgE rose afterward and then fell again.

Adult↗
PubMed1986

Specificity of the human IgE response to inhaled acid anhydrides.

Patients with work-related respiratory symptoms caused by inhaled acid anhydrides (trimellitic (TMA), phthalic (PA), tetrachlorophthalic (TCPA), and maleic anhydrides) have specific IgE antibody. The antibody is specific for a conjugate of the sensitizing anhydride (the hapten) and human serum albumin (HSA). We have investigated the specificity of the reaction to determine whether the antibody is directed against (1) the anhydride, (2) new antigenic determinants formed by conjugation of albumin with the anhydride, or (3) the complete anhydride-HSA conjugate. For the patients sensitized to TCPA and TMA, RAST inhibition studies demonstrate the anhydride-HSA conjugate to be a more effective inhibitor of RAST than the sodium salt of the anhydride or an anhydride-bovine serum albumin conjugate, whereas for those sensitized to PA, the free hapten is almost as an effective inhibitor as the conjugate. With each sera HSA conjugates of anhydrides to which the patient is not sensitized are weaker inhibitors than the sensitizing anhydride-albumin conjugate. These results provide strong evidence that for the patients sensitized to TCPA and TMA, the antibody combines with the anhydride and the spatially adjacent portion of the HSA molecule, whereas in the patients sensitized to PA, the antibody is specific for the hapten.

Albumins↗
PubMed1985

Interaction of smoking and atopy in producing specific IgE antibody against a hapten protein conjugate.

A survey was carried out of a population of workers exposed to tetrachlorophthalic anhydride, an acid anhydride epoxy resin curing agent known to cause asthma. Using a radioallergosorbent test with a tetrachlorophthalic anhydride human serum albumin conjugate, specific IgE antibody was detected in serum from 24 out of 300 factory floor workers exposed to tetrachlorophthalic anhydride. Of these 24, 20 (83.3%) were current smokers compared with 133 (48.2%) of 276 without antibody (p less than 0.01), and there was a weaker association with atopy, defined by skin tests with common allergens. Smoking and atopy interacted, the prevalence of antibody being 16.1% in atopic smokers, 11.7% in non-atopic smokers, 8.3% in atopic non-smokers, and nil in non-atopic non-smokers (p less than 0.025). Smoking may predispose to, and interact with atopy in, the production of specific IgE antibody to this hapten protein conjugate.

Adult↗
PubMed1983

Tetrachlorophthalic anhydride asthma: evidence for specific IgE antibody.

We describe seven women with asthma induced by occupational exposure to an acid anhydride, tetrachlorophthalic anhydride (TCPA), an epoxy resin hardening agent. Inhalation tests with TCPA at atmospheric concentrations of less than one tenth of a manufacturer's recommended exposure limit provoked asthmatic reactions in the four women tested. None had evidence of pretest bronchial hyperreactivity. Immediate skin prick test reactions were elicited in the seven subjects by a conjugate of TCPA with human serum albumin (TCPA-HSA) but not in others tested. Specific IgE antibody levels to TCPA-HSA, measured by radioallergosorbent test scores, were significantly elevated in the seven, but not in TCPA-exposed and unexposed comparison groups. These results imply that occupational asthma caused by TCPA is an allergic reaction mediated by specific IgE antibody.

Adult↗