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Biomedical subjects

W White

Publications and source records attributed to W White.

At least 73 records · Page 4Linked to original sources

The entrapment of [14C]ascorbic acid in human erythrocytes.

Radioactively labelled ascorbic acid and dehydroascorbic acid, when incubated with human blood, migrate irreversibly into human red blood cells. Isolation and characterization of the moieties trapped within the cells via infrared spectroscopy established both their identities as L-ascorbic acid. Evidence in the form of the degree of in vitro entrapment of ascorbic acid as a function of the times of incubation and the effect of incubation temperature, anion recognition site inhibitor, and active transport inhibitor on the rate of entrapment support the hypothesis that ascorbic acid is oxidized on or near the surface of the red blood cell to dehydroascorbic acid which migrates through the lipid portion of the cell wall and is reduced back to ascorbic acid within the cell. The resulting L-ascorbic acid can not pass through the cell wall and is therefore entrapped.

Ascorbic Acid↗

Chronic effects of clonazepam, phenytoin, ethosuximide, and valproic acid on learning in pigeons as assayed by a repeated acquisition procedure.

The acute and chronic effects of the antiepileptic drugs clonazepam (0.06, 0.13, and 0.25 mg/kg), phenytoin (2.5, 5, and 7.5 mg/kg), ethosuximide (40, 80, and 120 mg/kg), and valproic acid (40, 80, and 120 mg/kg) were evaluated in pigeons responding under a repeated acquisition procedure. At certain doses, acute administrations of all drugs impaired learning (i.e., increased errors) and reduced rate of responding. Appreciable tolerance developed to these effects with chronic exposure, although the physiological mechanism responsible for this outcome is unknown.

Animals↗

The preparation and testing of the proposed International Reference (IRP) Bermuda grass (Cynodon dactylon)-pollen extract.

A lyophilized candidate extract of Bermuda-grass (Cynodon dactylon) pollen, intended for use as an International Reference Standard, was prepared by pooling four individual candidate extracts. In preliminary investigations, the four candidate extracts encompassed a variety of extraction methods. The collaborative testing program simultaneously analyzed the proposed reference and the individual extracts and included 11 laboratories performing RAST inhibition, histamine release, crossed immunoelectrophoresis, crossed radioimmunoelectrophoresis, isoelectric focusing, sodium dodecyl sulfate gel electrophoresis, and protein determinations with a variety of reagents and methods. The four candidate extracts and the pooled reference were found to be equivalent. The stability of this extract has also been studied. This International Reference Preparation of Bermuda grass-pollen extract should be useful for research and industry.

Allergens↗

Effects of phenobarbital, clonazepam, valproic acid, ethosuximide, and phenytoin on the delayed matching-to-sample performance of pigeons.

The effects of phenobarbital, clonazepam, valproic acid, ethosuximide, and phenytoin were examined in pigeons performing under a delayed matching-to-sample procedure. Clonazepam, valproic acid, ethosuximide, and phenytoin typically reduced the rate of responding to the sample stimulus, whereas phenobarbital usually increased response rates at high doses. Phenobarbital, clonazepam, and valproic acid produced generally dose-dependent decreases in accuracy; ethosuximide and phenytoin failed to do so. These results suggest that there are qualitative as well as quantitative differences in the effects of anticonvulsant drugs under the delayed matching-to-sample procedure.

Animals↗

Freedom of information: can we afford to be anything but clinical?

Following the introduction of the Freedom of Information Code and Act in Victoria there have been numerous requests seeking the opportunity for patients and ex-patients to view their own records. This paper explores the clinical context within which patients traditionally have had, or not had, access to their own records, and the ways in which this is now altered by freedom of information legislation. The view is put forward that such disclosure in the past has always been within a clinical context whereas now there is potential for legislative intrusion into the psychiatrist/patient relationship of which the patient record is a part. A number of case examples is provided to exemplify the issues involved and the approach that the Victorian Health Commission has taken to resolve some of the difficulties.

Australia↗

Tumour-reactive lymphocytes stimulated in mixed lymphocyte and tumour culture. Clonal analysis of effector cells in cytotoxic and proliferative assays.

Lymphocytes from cancer patients were stimulated in mixed culture with autologous tumour (MLTC) or pooled allogeneic lymphocytes (MLC). Both protocols induced increased uptake of 3H-thymidine at 5 days and the appearance of lymphoblasts. Blasts were isolated on discontinuous Percoll gradients and either expanded as bulk cultures or cloned directly under limiting dilution conditions in the presence of conditioned medium containing IL-2. Results with MLTC-blast-CTC have been reported elsewhere. MLC-activated cultures lysed autologous tumour but not autologous lymphoblasts. Lysis of some allogeneic tumours, lymphoblasts from members of the inducing pool, and K562 was also apparent. MLC activated cultures did not undergo restimulation in response to autologous tumour or lymphocytes but were restimulated by leukocytes from pool members. MLTC clones showed autologous tumour-specific cytotoxic activity or cross-reactive proliferative responses with tumours of the same site and histology. The majority of MLC clones cytotoxic for autologous tumour were also specific and did not lyse allogeneic tumour, K562, or lymphoblasts from the inducing pool. Two clones lysed autologous tumour and pool members. None of the clones tested proliferated in response to autologous tumour following MLC activation but some were responsive to pool members and one clone was restimulated by autologous monocytes. No association was found between clone phenotype and function. The implication of these data is that the effector cells with activity against autologous tumour induced in MLC arose largely by transstimulation of in vivo-activated tumour reactive lymphocytes by IL-2 release rather than expansion of NK-like effectors or sharing of antigenic specificities between tumour and allogeneic lymphocytes. Since MLC activation of cancer patients lymphocytes does not induce proliferative responses to autologous tumour it is unlikely to be a useful procedure in preparing cells for immunotherapy protocols.

Antibodies, Monoclonal↗

Studies of cervicovaginal smears for the presence of actinomycetes.

Cytologic and direct fluorescent antibody techniques were used to detect the presence of Actinomyces israelii and Arachnia propionica in cervicovaginal smears collected from 100 women, 94 of whom did not use intrauterine contraceptive devices. In no case were these organisms found. The possible significance of these results is discussed.

Actinomyces↗

Effect of simple sugars on natural killing: evidence against the involvement of a lectin like mechanism in target recognition.

The spontaneous lysis of target cells sensitive to natural killer (NK) activity is accomplished in two distinct phases: (i) binding between target and effector cells and (ii) post-binding events leading to target cell destruction. To test the hypothesis that cell surface carbohydrate(s) might be involved in recognitive and/or lytic events, the binding and cytotoxicity of peripheral blood lymphocytes (PBL) towards NK sensitive K-562 targets was studied in the presence of simple sugars and after treatment of the targets with the antibiotic, tunicamycin. Lysis by peripheral blood lymphocytes was found to be inhibited by N-acetyl glucosamine, N-acetyl galactosamine and alpha-methyl mannoside in a dose-dependent manner under conditions where neither these sugars nor those (fucose, galactose) which had little effect on lysis inhibited the binding of effector cells to targets. Further, growth of K-562 in tunicamycin (which inhibits N-linked glycosylations occurring through the lipid intermediate pathway) with or without subsequent treatment with the enzyme neuraminidase, markedly reduced cell surface expression of sugars monitored by lectin binding. Treated cells showed no loss of NK susceptibility and were frequently more sensitive to lysis. Sugar inhibition profiles were the same as for untreated cells. These data suggest that carbohydrates are not the target sites of NK recognition but that simple sugars may have an inhibitory action at a later stage of the lytic process.

Acetylgalactosamine↗

Quantitative histochemical resolution of the oxidation-reduction and phosphate potentials within the simple hepatic acinus.

Glycerin-3-P, commonly known as alpha-glycerophosphate and dihydroxyacetone phosphate (DHAP) were measured in well defined microscopic samples of the simple liver acinus allowing a comparison of the glycerin-3-P/dihydroxyacetone-P-ratios of Zones 1 and 3 as a measure of the free NAD+/NADH ratio. The ATP/ADP X Pi quotients were determined in these same microscopic areas of the liver acinus as a measure of the phosphate potential. Brief ischemia was used to disturb the system. The results indicate that the oxidation-reduction and phosphate potentials are uniform throughout the entire liver lobule.

Animals↗

Restoring medical markets: implications for the poor.

Competition has become a popular prescription for the problem of rising health costs. One issue largely absent fom discussions of market systems and medicine, however, has been analysis of the implications for the poor. This paper explores the implications of proposals to use health maintenance organizations and vouchers to promote competition. We conclude that, as they stand, pro-competitive proposals could cause a significant deterioration in the position of the poor, especially if costs continue to rise, and that their effects are likely to be exacerbated by problems with implementation.

Community Participation↗

Anti-Km in a transfused man with McLeod syndrome.

An 18 year old man has red cells of the McLeod phenotype in the Kell system but does not have chronic granulomatous disease. His red cells show acanthocytic morphology and there is evidence of a compensated hemolytic state. Following an accident he was transfused with blood of common Kell type and made anti-K and anti-Km. Leukocytes from the patient are deficient in Kx antigen but the cells appear to have normal function. The mother is a carrier of the variant Xk allele and has a double red-cell populatio of McLeod cells and cells of common Kell type. The family may be informative with respect to linkage between the Xk and Xg loci. One of the mother's 5 brothers and one of her maternal uncles are possible Xk:Xg recombinants.

Acanthocytes↗

Resolution, sensitivity, and contrast in gamma-camera design: a critical review.

The performance of present-day gamma-cameras is examined from a historical perspective and the prospects for further improvements assessed. The author attempts to show quantitatively that spatial resolution of 25-cm field-of view cameras has reached a point where further advances can bring only diminishing returns clinically, unless improvements in sensitivity, or alternatively, in photon yield of the clinical procedure, are also realized. However, better image contrast due to developments in display technology and emission computed tomography may improve lesion detectability more directly than would an increase in resolution.

Humans↗

Fc receptors on human lymphocytes detected with double-coating indirect rosette formation.

The Fc receptor (FcR) on human lymphocytes is studied by using soluble immune complexes in antigen excess, prepared between ferritin and rabbit anti-ferritin, and a modification of Coombs' antigolbulin reaction (double-coating indirect rosette formation). 12% of human blood lymphocytes are shown to have Fc receptors. The FcR on lymphocytes is sensitive to pronase treatment, partially sensitive to trypsin digestion, and is inactivated after short glutaraldehyde fixation of lymphocytes. By cell fractionation experiments, FcR-positive lymphocytes were enriched in cell populations enriched with B cells.

Animals↗