In this report we describe a modified reverse phase HPLC method that avoids the solvent evaporation step and allows simple and rapid determination of retinol, alpha-tocopherol, alpha-carotene and beta-carotene and achieves complete separation of alpha- and beta-carotene. Retinyl acetate, alpha-tocopheryl acetate and retinyl palmitate in ethanol were added to serum as internal standards. Serum was then deproteinized with an equal volume of ethanol, and the lipid was extracted with ethyl acetate-butanol (1:1 v/v). A portion of this solution was injected into a C18 reverse phase chromatographic column and absorbencies of the vitamins and internal standards were measured at 292 nm for tocopherols, 325 nm for retinoids and 450 nm for carotenoids; peak-height ratios were used to quantify each vitamin. The analytical recoveries for retinol, alpha-tocopherol alpha- and beta-carotene at various concentrations tested were 95-103, 90-98, 92-99 and 94-96%, respectively. The intra- and interassay variations for low and high concentrations of retinol, alpha-tocopherol, alpha- and beta-carotene ranged from 2.4 to 6.7 for intraassay and from 4.3 to 8.5 for interassay replication. The detection limits were 1.25 (0.04), 19 (0.44), 0.35 (0.006) and 0.94 (0.017) micrograms/dL (delta mol/L) for retinol, alpha-tocopherol, alpha- and beta-carotene, respectively.

Carotenoids↗

PubMedDate not supplied

Effect of glucagon on carbohydrate-mediated secretion of glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (7-36 amide) (GLP-1).

BACKGROUND: The insulinotropic hormones, glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (7-36 amide) (GLP-1), regulate insulin secretion to nutrient intake and constitute the endocrine arm of the entero-insular axis. Glucagon has been implicated in the pathophysiology of conditions characterised by abnormal glucose tolerance such as obesity and diabetes mellitus although its effect on the entero-insular axis is not fully understood. Materials and methods We investigated the effect of exogenous glucagon on the entero-insular axis and its relation to gastric emptying in six healthy men aged [mean (+/-S.E.M. )] 23.6 (0.9) years with a body mass index of 24.0 (1.5) kg/m(2). Plasma glucose, GIP, GLP-1, insulin and paracetamol concentrations were measured before and after a 100 g oral carhohydrate load containing 1.5 g of paracetamol for 6 h during intravenous infusion of either glucagon or saline. RESULTS: When compared to the saline infusion, peak and integrated insulin and glucose concentrations were higher (p<0.05) following glucagon infusion. After 60 min paracetamol concentrations were lower (p<0.05) following glucagon infusion. Integrated responses for GIP and GLP-1 were markedly reduced following glucagon infusion. CONCLUSIONS: Exogenous glucagon in addition to its well-documented action of increasing glucose and insulin concentrations and delaying gastric emptying also markedly reduces GIP and GLP-1 secretion. The inhibition of GLP-1 soon after commencement of glucagon infusion supports a direct effect of glucagon on intestinal L-cells. We speculate that the marked inhibition of postprandial GLP-1 secretion by glucagon may be of importance in the pathogenesis of relative insulinopenia in Type 2 diabetes and in the development of reduced satiety in obesity and diabetes.

Acetaminophen↗

PubMedDate not supplied

Clinical guidelines: attitudes, information processes and culture in English primary care.

The application to clinical medicine of evidence-based clinical guidelines is an increasingly international policy prescription, yet research on how such guidelines might be implemented has tended to focus on change initiatives without seeking to understand change processes. This paper reports an empirical study of guideline implementation in UK general practice. Most GPs welcome guidelines as a means of improving care, though have reservations about their authority, relevance and effect on professional autonomy. 'Clan' organizational culture predominates and general practices do not generally have well-functioning internal arrangements for the management of clinical evidence and related information. We found no coherent relationships between these variables and practices' actual uptake of guidelines.

Attitude of Health Personnel↗

PubMedDate not supplied

Migration-related changes in the cytoskeleton of cultured neural crest cells visualized by the monoclonal antibody I-5G9.

An epitope recognized by the monoclonal antibody I-5G9 was expressed by all neural crest cells shortly after explantation into culture. At this time all neural crest cells actively migrated away from the neural tube. Immunoreactivity was localized intracellularly and organized into stress fiber-like filaments. Often, immunofluorescence was particularly high in short fibers in the lamellipodia of the leading edge of migrating cells. Two-week-old cultures had a diameter of 8-10 mm. At that stage a ring of immunoreactive cells was present at the periphery of each culture, an area where cells were still migratory. An inner concentric circle had reduced and more granular staining. In this area cells had ceased to migrate. In the center of the culture cells were multilayered, nonmigratory, and did not bind I-5G9. After creating a lesion in the nonreactive central region, some cells resumed migration into the lesioned area and reexpressed the epitope. I-5G9 staining and phalloidin fluorescence colocalized partially in some cells and completely in others. It is concluded that the epitope recognized by I-5G9 is expressed in a migration-dependent manner. The partial colocalization of I-5G9 and phalloidin fluorescence supports the notion that the epitope recognized by I-5G9 is specifically expressed in stress fibers of migratory cells, possibly in one of the actin-associated proteins or an F actin-associated protein complex.

Animals↗

PubMedDate not supplied

Flooding in vivo as research tool and treatment method for phobias: a preliminary report.

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Adolescent↗