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Biomedical subjects

P Wright

Publications and source records attributed to P Wright.

At least 109 records · Page 6Linked to original sources
PubMed1996

Excretion and distribution of ammonia and the influence of boundary layer acidification in embryonic rainbow trout (Oncorhynchus mykiss)

This study examined ammonia excretion by embryos of the rainbow trout (Oncorhynchus mykiss). The distribution of ammonia in relation to the H+ distribution and electrical potential was determined. The influence of the pH of the unstirred layer (USL) of water next to the external surface of the embryo was also assessed. Eyed-up embryos (35­40 days post-fertilization) were exposed to various external water conditions [pH 6.0, pH 10.0, 1.6 mmol l-1 NaCl, 0.0 mmol l-1 NaCl, 0.2 mmol l-1 NH4Cl, 2.5 mmol l-1 borax buffer (Na2B4O7.10H2O), 2.5 mmol l-1 Hepes, 0.1 mmol l-1 amiloride] for 30 min and ammonia excretion rates, ammonia concentration in the perivitelline fluid (PVF) and yolk, and the pH of the PVF, yolk and USL were measured. The rate of ammonia excretion was dependent, in part, on the partial pressure gradient of NH3 ( PNH3) from the PVF to the USL. Exposure to water of pH 6 increased, whereas NH4Cl or pH 10 exposure decreased, ammonia excretion rates. Elevated external Na+ levels also influenced the rate of ammonia excretion, but neither Na+-free water nor amiloride had any effect. The distribution of ammonia between the PVF and USL was dependent on the H+ distribution, but ammonia was distributed according to the electrical potential between the PVF and yolk. The USL was 0.32 pH units more acidic than the bulk water. Addition of buffer to the external water eliminated the acid USL and decreased ammonia excretion rates. We conclude that rainbow trout embryos excrete ammonia primarily as NH3, but when external Na+ levels are elevated, ammonia excretion may be independent of the PNH3 gradient. The acidic USL next to the chorion probably facilitates NH3 diffusion by maintaining the PNH3 through the conversion of NH3 to NH4+ upon entry into the USL.

Journal Article↗
PubMed1996

Left-handedness increases injury risk in adolescent girls.

In a self-report survey of a representative national sample of 4081 Scottish schoolchildren, injuries requiring medical assistance were more common in left-handers; these were also more severe and likely to involve an overnight stay in hospital. Particularly at risk were adolescent girls with a 32% greater chance of being injured if they were left-handed compared with their right-handed peers. The corresponding relative risk for boys was not significant.

Adolescent↗
PubMed1995

Expression and regulation of kainate and AMPA receptors in uncommitted and committed neural progenitors.

Here we review experimental evidence of non-NMDA glutamate receptor expression in the embryonic central nervous system. AMPA- and kainate-preferring glutamate receptor subunit mRNA transcripts are detected in embryonic neurons, glia and neural progenitors. Functional assays demonstrate that in some cell subpopulations ionotropic glutamate receptors are expressed by progenitors before synapse formation and terminal differentiation, and may be present before lineage determination is specified. The activation of these receptors triggers induction of immediate early gene transcription in progenitor cells. The cloning and transcriptional analysis of upstream regulatory regions of glutamate receptor genes governing their temporal and tissue-specific expression are also discussed.

Animals↗
PubMed1995

Identifying substance abuse in maltreating families: a child welfare challenge.

Studies of the link between parental substance abuse and child maltreatment suggest that chemical dependence is present in at least half of the families who come to the attention of child welfare authorities for child abuse and neglect. Parental substance abuse is thought to be a primary factor in greatly increased rates of children entering foster care over the past decade. It is also a clear risk factor for child mental health problems and poor developmental outcomes in children. At the same time, however, minimal attention is often given to training child protective services workers and other child welfare personnel in identifying and confronting substance abuse in families on their caseloads. The authors explore standardized methods developed for screening for substance abuse among various populations and suggest ways of adapting these screening devices for families reported for child maltreatment. They identify assessment and treatment considerations in substance abusing families as well.

Adult↗
PubMed1995

Topical heparin in the treatment of ligneous conjunctivitis.

BACKGROUND: Ligneous conjunctivitis is a rare acute or subacute membranous conjunctivitis of unknown etiology for which no generally accepted form of treatment is available. METHODS: Between 1972 and 1993, 17 patients with ligneous conjunctivitis were treated with excision biopsy, meticulous hemostasis, and immediate, intensive topical treatment with heparin, steroids, and, in 12 patients, alpha-chymotrypsin until all signs of conjunctival inflammation had subsided. RESULTS: On histologic examination, the lesions consisted of subepithelial deposits of fibrin in all patients. Eight patients had no recurrence (mean follow-up, 33.1 months) and in four patients the conjunctivitis was controlled after one repeat excision and topical treatment (mean follow-up, 40.3 months). One patient had three recurrences before responding to treatment (follow-up, 24 months). In four patients, treatment was unsuccessful, although lesion-free intervals were longer than usually seen in this condition (mean, 7.8 months). CONCLUSION: These results suggest that intensive and early use of topical heparin may improve therapy results in ligneous conjunctivitis.

Acute Disease↗
PubMed1995

An association study of a neurotrophin-3 (NT-3) gene polymorphism with schizophrenia.

Since abnormalities of brain development play a role in the aetiology of schizophrenia, growth factors, known to play a role in neurodevelopment, such as neurotrophin-3 (NT-3), are therefore candidate genes for this disorder. The A3/147 bp allele of a dinucleotide repeat polymorphism in the promoter region of the NT-3 gene has been reported as occurring more frequently in a sample of Japanese schizophrenics compared to controls. We have determined the frequency of alleles of this polymorphism in 175 Caucasian schizophrenic patients and 147 control subjects. The patient and control samples showed no significant deviation from Hardy-Weinberg equilibrium and, in a test of allalleles, the patients and controls did not differ significantly in allele frequencies. However, the male schizophrenics were more likely than male controls to have the A3/147 bp allele (P = 0.029).

Alleles↗
PubMed1995

Placebo controlled trial of fusidic acid gel and oxytetracycline for recurrent blepharitis and rosacea.

A prospective, randomised, double blind, partial crossover, placebo controlled trial has been conducted to compare the performance of topical fusidic acid gel (Fucithalmic) and oral oxytetracycline as treatment for symptomatic chronic blepharitis. Treatment success was judged both by a reduction in symptoms and clinical examination before and after therapy. Seventy five per cent of patients with blepharitis and associated rosacea were symptomatically improved by fusidic acid gel and 50% by oxytetracycline, but fewer (35%) appeared to benefit from the combination. Patients with chronic blepharitis of other aetiologies did not respond to fusidic acid gel but 25% did benefit from oxytetracycline and 30% from the combination. Our results demonstrate the need to investigate patients with blepharitis for concomitant rosacea as they respond well to targeted therapy.

Blepharitis↗
PubMed1995

Maternal influenza, obstetric complications, and schizophrenia.

OBJECTIVE: Epidemiologic studies have reported an association between prenatal exposure to influenza and adult schizophrenia. The authors studied this association in individual patients with schizophrenia and also investigated the relationship of obstetric complications, another postulated risk factor, to adult schizophrenia. METHOD: Using a structured interview instrument, the authors assessed infections during pregnancy, obstetric complications, gestational age, and birth weight by interviewing the mothers of 121 patients with DSM-III-R schizophrenia. RESULTS: Significantly more infections were reported in the second trimester of the patients' gestations than in the combined first and third trimesters. Influenza accounted for 70% of second-trimester infections. Patients with schizophrenia whose mothers reported having influenza during the second trimester were almost five times more likely to experience at least one definite obstetric complication than were patients who were not exposed to influenza during the second trimester; the exposed patients weighed a mean of 210 g less at birth than the unexposed patients. CONCLUSIONS: Maternal influenza during the second trimester may impair fetal growth and predispose to obstetric complications and lower birth weight in a proportion of individuals destined to develop schizophrenia.

Adult↗
PubMed1995

Effect of clozapine on d-fenfluramine-evoked neuroendocrine responses in schizophrenia and its relationship to clinical improvement.

BACKGROUND: Clozapine is an effective antipsychotic that has high affinity for serotonin type 2 (5-HT2) receptors. The importance of 5-HT antagonism in the overall clinical efficacy of clozapine is unclear. Using a neuroendocrine strategy we tested the hypothesis that clinical response to clozapine is related to alteration in 5-HT function. METHOD: Ten treatment-resistant schizophrenic subjects were treated with clozapine for a mean of 10.3 (s.e. 0.9) weeks; d-fenfluramine (DFEN) challenge tests were performed before and after treatment with concurrent clinical ratings (BPRS, SAPS, SANS) made at the time of testing. RESULTS: All patients showed clinical improvement following treatment with clozapine. In addition, clozapine produced a significant attenuation of prolactin (PRL) and cortisol (CRT) response to DFEN challenge. Change in symptom ratings correlated significantly with reduction in PRL response to DFEN challenge. CONCLUSIONS: These data show that functional alterations occur in the 5-HT system following response to clozapine and lend support to studies suggesting that 5-HT is an important component to the spectrum of action of clozapine.

Adult↗
PubMed1995

Induction of ornithine-urea cycle enzymes and nitrogen metabolism and excretion in rainbow trout (Oncorhynchus mykiss) during early life stages

The ornithine­urea cycle (OUC) is present in elasmobranch fish and many terrestrial vertebrates. Recently, a functional OUC has been reported in a few teleost species, suggesting that all teleost fish have the genes for the OUC, but expression is relatively rare. We investigated the possibility that the OUC is expressed during early development in trout as a mechanism for detoxifying ammonia produced from the catabolism of yolk protein. We followed ammonia and urea excretion rates, tissue ammonia and urea levels and OUC enzyme activities in rainbow trout up to 93 days after fertilization. Both ammonia and urea tissue concentrations increased several-fold in the first 40 days after fertilization (embryo stage), peaking at 1.7 mmol N l-1 and 2.5 mmol N l-1, respectively. Ammonia excretion could be detected in 4-day-old embryos, but urea excretion was not initiated until after hatching (day 45). Urea excretion in larval fish (days 42­93) increased several-fold and by day 93 was 14 % of total nitrogen excretion, as found in adult trout. Glutamine synthetase (GSase) and arginase activities were detected in 'whole animal' homogenates just after hatching and the levels of activity increased markedly to day 93. Carbamoyl phosphate synthetase (CPSase) and ornithine transcarbamylase (OTCase) were first detected in 40-day-old embryos; activities peaked between days 53 and 71 and then subsequently decreased. Adult liver enzyme activity for GSase was several-fold lower than in whole larval trout and OTCase and CPSase III (glutamine- and N-acetylglutamate-dependent CPSase catalysing the first step of the OUC) activities were essentially absent in adult liver. We conclude that embryonic and larval trout are primarily ammoniotelic. Urea is synthesized immediately after fertilization, but is not excreted until after the embryo is hatched. The results provide evidence for the presence of the OUC in larval rainbow trout, since four of the OUC enzymes are induced just after hatching and the levels of activity are relatively high compared with those in adult liver tissue. Furthermore, we suggest that all teleosts have retained the OUC genes, which are expressed only during certain stages of development (embryogenesis), and in a few rare species expression is maintained throughout the life cycle to cope with unusual environmental conditions (e.g. alkaline water, air exposure).

Journal Article↗
PubMed1995

Ammonia and urea metabolism in relation to gill function and acid-base balance in a marine elasmobranch, the spiny dogfish (Squalus acanthias)

Nitrogenous waste excretion in resting dogfish occurred largely (>90 %) as urea-nitrogen (urea-N) efflux across the gills, with a very small urea efflux via the kidney. Ammonia excretion, almost entirely at the gills, accounted for less than 3 % of total nitrogen excretion. Given the extremely high blood urea levels (approximately 640 mmol-N l-1) 'retained' for osmoregulation, and blood ammonia levels (approximately 80 µmol-N l-1) comparable to those of teleosts, the gills of resting dogfish were exceptionally impermeable to both urea and ammonia. Experiments investigated the origins of these low permeabilities and the responses of urea-N and ammonia-N excretion and acid­base status to 6 h infusions with iso-osmotic solutions of NaCl (control), NH4Cl, NaHCO3, urea and its analogues thiourea and acetamide. NaCl had no effects, whereas NH4Cl loading caused intense acidosis and marked elevation of acidic equivalent, ammonia-N and urea-N excretion rates, the latter despite unchanged blood levels of urea-N. Apparent branchial ammonia permeability increased greatly. Acidosis resulted from both stimulated urea production and branchial NH3 loss, the former making the larger contribution. NaHCO3 loading caused intense alkalosis, a marked elevation of basic equivalent excretion and a moderate stimulation of urea-N excretion. Blood urea-N levels were again unchanged. Infusion of urea itself raised blood urea-N levels, but initially reduced branchial urea-N excretion. Acetamide and thiourea infusions both moderately elevated branchial urea-N excretion. We suggest that the low ammonia permeability may arise metabolically from an ammonia scavenging system in the gills, that a 'back-transport' mechanism in the gills may contribute to the low urea permeability, and that the dissociation between blood urea-N levels and excretion rates may reflect urea production at extrahepatic sites. These studies demonstrate that urea synthesis in the dogfish is linked more to nitrogen availability than to acid­base status.

Journal Article↗
PubMed1995

Modification tolerability of soybean proglycinin.

Proglycinins containing multiple modifications, that is, with two kinds of single modifications, designed previously to improve food functions, were assessed for ability to form proper conformations. This was done to discover the modification tolerability of proglycinin. Based on our results, three new criteria are proposed for judging formation of proper conformations. Our results suggest that proglycinin molecules tolerate different combinations of single modifications without misfolding.

Amino Acid Sequence↗
PubMed1995

Publication of patient-related oncology nursing research.

PURPOSE/OBJECTIVES: To identify publication rates of patient-related studies in oncology nursing research. DESIGN: Survey of publication rates of patient-related research. These results are one component of an integrative review and meta-analysis of a decade of patient-related oncology nursing research. SAMPLE: Authors of abstracts addressing patient-related oncology nursing research submitted for presentation at Oncology Nursing Society (ONS) Congresses from 1981 to 1990 (N = 237) that met the inclusion criteria for the Integrative Review of Oncology Nursing Research. METHODS: Survey letters sent to one author of each patient-related oncology nursing research abstract published in the ONS Congress proceedings. MAIN OUTCOME VARIABLE: Rate of publication. FINDINGS: Of 237 responses, 89 (38%) indicated that the study had been published by late 1991 in a peer-reviewed journal or as a book chapter; 148 abstracts (62%) were unpublished. Study abstracts accepted for podium or poster presentation at ONS Congresses were more likely to be published than those not accepted. CONCLUSIONS: The majority of patient-related oncology nursing research submitted for presentation at ONS Congresses was not published and not readily available for nurses to evaluate for use in clinical practice. Lack of nursing research publication appears to be a serious threat to knowledge development and dissemination in oncology nursing. IMPLICATIONS FOR NURSING PRACTICE: Systematic ways to organize research findings in nursing need to be developed. Experienced researchers and authors need to encourage and assist nurses in conducting research, writing, and submitting manuscripts.

Abstracting and Indexing↗