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Biomedical subjects

C Davies

Publications and source records attributed to C Davies.

At least 163 records · Page 9Linked to original sources
PubMed1989

Joint report of the Third International Bovine Lymphocyte Antigen (BoLA) Workshop, Helsinki, Finland, 27 July 1986.

Two hundred and eighty-two alloantisera were submitted by 20 participating laboratories from 13 countries and tested against lymphocytes of 1298 cattle. The cell panel consisted of samples from 38 Bos taurus breeds, 11 Bos taurus crossbreeds, 4 Bos indicus breeds, 6 Bos taurus x Bos indicus, and a variety of other crossbred populations. Using a standardized lymphocytotoxicity test, all 17 previously identified BoLA specificities were confirmed. The workshop produced agreement on 16 new lymphocyte alloantigenic specificities. Three of the new specificities behaved as splits of previously identified BoLA specificities. Four of the new specificities behaved as alleles at the agreed BoLA-A locus. Seven new specificities are tentatively assigned to the BoLA-A locus but require further definition. Two new specificities may represent products of a second closely-linked BoLA locus.

Animals↗
PubMed1989

An effective combination of anaesthetics for 6-h experimentation in the golden Syrian hamster.

The anaesthetics described for use in hamsters to date are suitable for the performance of short-term experimentation. However, an anaesthetic regimen was required which would provide a stable preparation for 6 h and hence, a suitable combination was developed. In the first set of experiments, the effect of anaesthetics (chloralose, urethane, and pentobarbital) were examined alone and in combination on arterial blood measurements. In the second set of experiments the effect of the combination of anaesthetics on arterial blood measurements and minute ventilation was examined for up to 6 h. Chloralose, urethane and pentobarbital when used alone in the hamster were considered inadequate for our needs. Chloralose did not produce adequate surgical anaesthesia whereas urethane and pentobarbital resulted in marked respiratory depression. Urethane also produced a trend towards metabolic acidosis. In contrast, the combination of agents resulted in surgical anaesthesia and the arterial blood measurements were adequate. Further, the use of the combination of anaesthetics in hamsters resulted in a stable preparation where arterial blood measurements and minute ventilation were maintained in a good range for up to 6 h. The combination of chloralose, urethane and sodium pentobarbital in hamsters should prove useful in long-term non-recovery experimentation which requires early surgical intervention, minimal respiratory depression and an even depth of anaesthesia.

Anesthesia↗
PubMed1988

Comparison of the performance and clinical utility of a carboxy-terminal assay and an intact assay for parathyroid hormone.

A comparison of the performance of a two-site immunochemiluminometric assay for intact parathyroid hormone with that of an in-house radioimmunoassay for carboxy terminal parathyroid hormone has been performed on samples from unselected patients being investigated for hypercalcaemia. The intact parathyroid hormone assay was found to be a simple and robust technique with a broad working assay range (CV less than 10% between 1.8-212 pmol/l) and a detection limit of 0.2 pmol/l. Clinically it is superior to the carboxy terminal assay in its ability to distinguish between patients with hyperparathyroidism from those with other causes of hypercalcaemia especially in the presence of impaired renal function.

Adult↗
PubMed1988

Self-cleaving viroid and newt RNAs may only be active as dimers.

Avocado sunblotch viroid (ASBV) is a 247-nucleotide, single-stranded, circular RNA. It is considered to replicate via a rolling-circle mechanism in which circular, monomeric plus and minus RNAs act as templates for the synthesis of longer-than-unit-length precursor RNAs. Processing of these RNAs in vivo may occur by a self-cleavage reaction, as indicated by ability of dimeric, linear plus and minus ASBV RNAs to specifically self-cleave in vitro with the excision of a monomeric RNA with 5'-hydroxyl and 2',3'-cyclic phosphodiester termini. A similar self-cleavage reaction has also been reported to occur in an RNA transcript containing a dimeric copy of a tandemly repeated, 330-base-pair sequence of the newt genome. Based on comparisons with self-cleaving plant viral satellite RNAs, hammerhead-shaped active structures, each containing one self-cleavage site, were proposed for the plus and minus ASBV RNAs and the newt RNA, but the stability of these hammerheads has been questioned. Here, more stable active structures that contain two self-cleavage sites are proposed and data supporting these models are presented.

Animals↗
PubMed1988

Further implications for the evolutionary relationships between tripartite plant viruses based on cucumber mosaic virus RNA 3.

The nucleotide sequence of the RNA 3 of the Q-strain of cucumber mosaic virus (Q-CMV) has been reinvestigated and supporting partial amino acid sequence data obtained for the coat protein. Corrections to the previously published sequence of RNA 3 [A. R. Gould and R. H. Symons (1982) Eur. J. Biochem. 126, 217-226] result in changes to the size and composition of the putative 3a and coat proteins. Analysis of the nucleotide sequence revealed a 14-nucleotide sequence present in the intercistronic regions of the RNA 3 molecules of both Q-CMV and brome mosaic virus (BMV). This sequence, which is closely related to sequences previously detected in the 5'-untranslated region of Q-CMV and BMV RNAs 1 and 2 [M. A. Rezaian, R. H. V. Williams, and R. H. Symons (1985) Eur. J. Biochem. 150, 331-339], may be important in the control of RNA synthesis. Computer-assisted comparisons indicate an ancestral relationship between the 3a proteins of CMV, BMV, and alfalfa mosaic virus (AMV) and between the coat proteins of CMV and BMV. These comparisons significantly extend previous observations regarding the close evolutionary relationships within the plant tripartite virus group.

Amino Acid Sequence↗
PubMed1987

Viewpoint. Things to come: the NHS in the next decade.

This paper offers an interpretation of contemporary developments in Britain's National Health Service which suggests that a major transformation is under way, the contours of which, while visible, are not yet fully appreciated or understood. The analysis is in sharp contrast with that recently proposed by Klein and deliberate comparisons are drawn. The paper is in three main sections. The first briefly summarises Klein's position. The second takes issue with certain of his views, notably those on structural change, but also to some extent those on the relevance of the private sector. Welfare pluralism is posited as the most plausible future for health care and as a phenomenon as yet not well understood in Britain's health care sector.

Forecasting↗
PubMed1987

The metabolism of 2,5-diphenyloxazole (PPO) in human lymphocytes and rat liver microsomes.

The oxidative metabolism of 2,5-diphenyloxazole (PPO) is associated with 3-methylcholanthrene inducible cytochrome P-450. The major metabolite formed has m/z of 237, corresponding to hydroxylated PPO. All the possible hydroxylated metabolites of PPO were synthesized and characterized, enabling the assignment of a structure for the major metabolite and two minor metabolites. The metabolites are easily extracted and their fluorescence is quantifiable in alkaline medium with a sample fluorescence to blank fluorescence ratio of 400:1. A sensitive HPLC assay of PPO metabolism was also developed. PPO metabolism is readily catalyzed by 3-methylcholanthrene-induced rat liver microsomes and strongly inhibited by alpha-naphthoflavone, but poorly inhibited by metyrapone or SKF 525A, indicating the involvement of cytochrome P-448 or P1-450 in the metabolism of PPO. With human lymphocytes the method has proven to be a good indicator of "aryl hydrocarbon hydroxylase" (AHH) activity, correlating well with AHH assays using benzo(alpha)pyrene (BP) as a substrate. Both the induced BP and PPO metabolism by human lymphocytes is inhibited by alpha-naphthoflavone, but not by metyrapone.

Animals↗
PubMed1986

Characterization of human mononuclear cells after positive selection with immunomagnetic particles.

We have investigated the possibility to employing magnetic monodisperse polymer particles for positive selection of human peripheral blood mononuclear cell populations. By carefully titrating the ratio between particles and cells we succeeded in isolating a number of cell populations that could be cultivated subsequently in vitro for functional studies. The success of the procedure is partly dependent on the properties of the monoclonal antibodies used to sensitize the cells. Provided these antibodies do not react with membrane structures involved in the transduction of activating signals, highly purified, quiescent cell populations can be recovered in a single fractionation step. In most instances particles will detach from the isolated cells by overnight culture, and the particles can then be removed from the system by a suitable magnet. T lymphocytes, subpopulations of T lymphocytes, and B lymphocytes have been isolated in this way and studied in a variety of functional assay systems. Comparison with cells obtained after negative selection clearly demonstrates the usefulness of this technique, especially if the membrane marker selected for it is not directly engaged in the activation processes.

Antibodies, Anti-Idiotypic↗
PubMed1986

Depression and anxiety in patients undergoing diagnostic investigations for head and neck cancers.

Patients attending a regional head and neck Oncology Unit were assessed for depression and anxiety (using the Leeds self-assessment scales) before diagnostic biopsy investigations. At the time of the assessments, neither patients nor investigators knew the biopsy results. Patients whose biopsies subsequently proved positive (showing the presence of a tumour) had significantly higher depression scores than those whose biopsies were negative. Differences in mean anxiety scores did not differ between groups. It is suggested that depression is part of the clinical picture of head and neck cancer.

Adult↗
PubMed1985

Antibodies to surface IgM and IgD increase the expression of various class II antigens on human B cells.

Antibodies to surface IgM and IgD were found to induce increased expression of class II antigens on normal and neoplastic human B cells within 24 h of stimulation. Antigens associated with different class II sub-locus genes (DC, DR and SB) were all found to be increased as determined by monoclonal antibodies (Leu-10 and B 3/4 for DC, D 1/12 for DR and MHM4 for SB-associated antigens). The increased expression of class II antigens was selective as anti-immunoglobulins failed to increase expression of other surface antigens such as B1 and beta 2-microglobulin. The effect of anti-mu and anti-delta could be blocked specifically by corresponding myeloma proteins suggesting that antibodies to surface IgM and IgD, respectively, were responsible for the effect observed. Moreover, antibodies to another surface antigen (B1) failed to induce such changes. Increased class II antigen expression appeared to be dependent on protein synthesis, and early changes in ion fluxes, but could not be elicited by membrane depolarization as reported in murine systems.

Antibodies, Anti-Idiotypic↗