Biomedical subjects
Publications and source records attributed to R Crouch.
Telephone advice systems can deliver a high-quality, responsive service. There is potential for development of the practice nurse role as telephone adviser in primary care. This study identifies a need for training nurses in the role of telephone adviser.
Comprehensive management of asthma includes proper use of medication adjustments in patient lifestyle, exercise conditioning, and patient education to maximize self-management capabilities. Pulmonary rehabilitation programs have used these strategies successfully to improve the functional status and reduce the health care costs of patients with chronic obstructive pulmonary disease. Adapting these programs to the asthmatic population is an important and cost-effective goal.
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Feelings engendered during 585 triage nursing assessments made by a total of 10 nurses were studied. Marked differences in nurses' feelings were demonstrated towards patients attending the accident and emergency (A&E) department with 'primary care' needs compared with those assessed as having 'A&E' needs. In particular, nurses demonstrated more negative feelings, in the form of less sympathy, more irritation and less motivation to help, towards patients with 'primary care' needs. Nurses' feelings were adversely affected by delays in patient presentation following the occurrence of illness or injury. Nurses perceived patients' attendance as illegitimate when it had deviated from expected norms of health-care-seeking behaviour. These findings were elicited using visual analogue scales completed immediately following the triage assessment of the patients. This work is part of a larger study into developing the primary care role of accident and emergency nurses. The culture of the A&E department is discussed, and the need to challenge and change this culture to ensure it becomes more responsive to individual patients' needs is advocated. This paper calls for development of triage training and education and further investigation into the effects of nurses' attitudes on patient assessment.
RNase H has been clearly implicated in vitro in mediating some antisense effects. In vivo evidence is limited to experiments performed in Xenopus oocytes in which antisense oligonucleotides are microinjected. In other mammalian cell systems scant data have been obtained to support or deny a role for RNase H as an antisense mediator in vivo. These experiments were designed to test the hypothesis that RNase H mediates the MYC antisense-induced reduction in MYC protein observed in the human monocytic leukemia cell line U937. A bacterial RNase H-containing episomal replicon was constructed and stable transfectants were obtained which expressed E coli RNase H in their cytoplasm at a 10-fold higher level than endogenous RNase H. These cells failed to demonstrate heightened sensitivity to MYC antisense (phosphorothioate, end capped and phosphodiester) compared with untransfected or E coli RNase H antisense transfected cells. PCR analysis of each transfectant treated and untreated with MYC antisense failed to demonstrate the appearance of truncated MYC mRNA. These results do not support a role for RNase H in the mediation of MYC antisense-induced MYC protein reduction and growth inhibition in U937 cells.
With the current emphasis on reducing patient waiting times, accident and emergency nurses may be tempted to close the doors on what they consider to be 'inappropriate attenders'. The author warns that public perceptions of A&E are often at odds with the nurses view, and that all patients should have access to accident and emergency services. This article takes a critical look at triage since its inception as a means of assessing wounded soldiers during the first world war. He explores patient assessment in accident and emergency departments and nurses' attitudes towards the 'inappropriate attender', highlighting the need for caution when dealing with enquiries from the general public.
An increased incidence of colonic cancer is associated with chronic inflammatory bowel disease. Sulphasalazine, metronidazole and more recently, modified forms of 5-aminosalicylic acid are used for maintenance therapy of inflammatory bowel disease. In a series of experiments, we used the 1,2-dimethylhydrazine animal model of colonic cancer in conjunction with these drugs, to study the effect on the development of colon cancer. Inbred male Wistar rats were divided into groups receiving orally: metronidazole 18 mg Kg-1 dy-1; sulphasalazine 60 mg Kg-1 dy-1; 5-aminosalicylic acid 30 and 60 mg Kg-1 dy-1 and olsalazine 60 mg Kg-1 dy-1 administered daily. Half of each group also received weekly injections of DMH 40 mg Kg-1. Metronidazole, sulphasalazine and 30 mg Kg-1 dy-1 5-aminosalicylic acid were co-carcinogenic, increasing either the number of cancers or tumour size. In contrast 60 mg Kg-1 dy-1 5-aminosalicylic acid inhibited tumour size and olsalazine had no effect. These results may have a bearing on long term maintenance therapy in inflammatory bowel disease.
Levels of rhodopsin in the photoreceptors of Long-Evans rats were reduced by approximately 55% through dietary deprivation of vitamin A. The interaction of visual pigment with G-protein was examined in receptor outer segment (ROS) membranes obtained from these animals. A binding assay was used to quantitate affinity of the visual pigment in unbleached and bleached ROS membranes for the alpha and beta subunits of exogenous G-protein. Extents of binding were similar to those observed for ROS membranes of rats raised on a normal (vitamin A-supplemented) diet. The results are consistent with a normal capacity for G-activation by photoactivated rhodopsin (R*) in vitamin A-deprived animals. They further indicate that "free opsin" arising in vitamin A deficiency, unlike R*, has relatively low affinity for G-protein.
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The cornea has inherent protection from superoxide radicals from the presence of superoxide dismutase. However, the dismutation of these radicals results in the generation of hydrogen peroxide. The corneal scavenging systems for hydrogen peroxide is minimal as there are only low levels of catalase and glutathione peroxidase present. We have demonstrated the cytolytic capabilities of oxygen radicals in the cornea and reversed this lysis with catalase. These data indicate that hydrogen peroxide is the primary damaging agent in this system.
Cultured human and rat corneal epithelial cells with 51Cr incorporated were used as a model to test the cytolytic action of four common preservatives. Benzalkonium chloride, chlorohexidine and thimerosol were all found to lyse greater than 40% cells when incubated for fifteen minutes at concentrations in clinical use in topical ophthalmic medications. Chlorobutanol is the only preservative tested which has a low level of cytotoxicity (10%) and which, under these conditions, can be considered a safe preservative using cytolytic activity as the means of criteria.
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Superoxide dismutase has been isolated from canine retina and compared to the commercial erythrocyte enzyme. The two enzymes have been characterized by biochemical and immunochemical methods. By the criteria used (enzymatic activity, immunoactivity, absorption spectra, electrophoretic properties, amino acid analyses and peptide maps), the two enzymes are completely homogeneous.
In biochemical and electrophysiologic studies employing the bullfrog (Rana catesbeiana) and the rat, the authors examined the interaction of opsin and an 11-cis-locked analog of retinal. In previously bleached preparations of bullfrog receptor outer segments (ROS) and isolated retinas, incubation with the aldehyde form (I) of the analog leads to the appearance of a pigment that is degraded slowly by hydroxylamine but is relatively resistant to photolysis. In the ROS preparation, the analog pigment (lambda max of difference spectrum congruent to 497 nm) also forms on incubation with NADP+ and the alcohol form (II) of the analog. In vitamin A deprived rats possessing only approximately 45% of the normal complement of rhodopsin, intraperitoneal injection of II leads within 1 day to the appearance of the analog pigment in the photoreceptors, at levels representing a major fraction of the opsin initially available for pigment formation. Formation of the analog pigment appears to have no significant effect on the sensitivity of electroretinographic b-wave responses recorded from the rat eye; furthermore, administration of II appears to suppress the sensitizing activity of all-trans retinol injected 1 day later. The data are discussed in relation to other studies examining chromophore-opsin interactions and electrophysiologic changes associated with the formation of rhodopsin in situ.
Angiosarcoma of the liver has been reported to be associated with the long-term use of androgenic-anabolic and oestrogenic steroids. It has been suggested that this tumour might develop in women after long-term exposure to oral contraceptive steroids, although this association has not yet been reported. We present here the clinical and pathological findings in a 42-year-old woman who died of hepatic angiosarcoma after taking oral contraceptive steroids for 10 years.
5,6-Dihydroretinal and 5,6-dihydro-1,1,5,9,13-desmethylretinal are synthesized, and their all-trans isomers are shown to form pigment analogues (lambda max at 475 and 460 nm, respectively) of bacteriorhodopsin (purple membrane protein). The shift of the absorption maximum od the pigment from that of the protonated Schiff base of the chromophore for 5,6-dihydrobacteriorhodopsin is small compared to that of the native pigment, suggesting that negative charges similar to those controlling the lambda max of visual pigment rhodopsin exist near the cyclohexyl ring. Both pigment analogues undergo reversible light-induced spectral shifts reflecting cyclic photoreactions of the pigments. These results indicate that the absence of the C-5--C-6 double bond and of the five methyl groups of retinal does not abolish the photochemistry of these pigment analogues and strongly suggest that these structural features are not directly required for the photoreactions of native bacteriorhodopsin. The apparent rates of the photochemical transformations of these artificial pigments are quite different from those of bacteriorhodopsin. A working hypothesis is proposed for the photocycle of the pigment analogues, which includes a slower light-induced cycling rate (for the light-adapted pigments) than that of native bacteriorhodopsin and an increased rate of dark adaptation. When incorporated into egg lecithin vesicles both pigment analogues show proton pumping ability, again indicating that the missing double bond and the methyl groups are not structurally required for the function of the pigments.
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