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Biomedical subjects

M Davies

Publications and source records attributed to M Davies.

At least 289 records · Page 16Linked to original sources
PubMed1993

The Diagnostic Interview Schedule for Children-Revised Version (DISC-R): II. Test-retest reliability.

OBJECTIVE: Test-retest reliability and internal consistency of the Diagnostic Interview Schedule for Children-Revised Version (DISC-R) were examined to evaluate the effects of a recent revision process. METHOD: A sample of outpatients 11 to 17 years old and their parents were administered the DISC-R in a test-retest design. RESULTS: For the parent interview, four diagnoses had sufficient cases to examine reliability; agreement was good to excellent for three of these. For the child interview, two of the four diagnoses with adequate cases showed good or excellent reliability. Using a combined parent-child algorithm, three of five diagnoses showed good or excellent reliability. Test-retest reliability for symptom scales was excellent for the parent DISC-R and good for the child version, except for oppositional defiant disorder. Maternal depressive symptoms did not affect reliability of reporting about the child's symptomatology. Internal consistency was satisfactory for symptom items comprising most diagnoses. CONCLUSIONS: Although some revision of the instrument will be necessary, the findings from this study suggest that the DISC-R is a promising research instrument for the diagnosis of psychopathology in older children and adolescents.

Adolescent↗
PubMed1993

The Diagnostic Interview Schedule for Children-Revised Version (DISC-R): III. Concurrent criterion validity.

OBJECTIVE: To examine the concurrent criterion validity of the Revised Diagnostic Interview Schedule for Children (DISC-R), a structured lay-administered instrument designed for use in community studies, under conditions designed to provide strict controls for information and method variance. METHOD: The DISC-R was compared with a semistructured clinical interview that covered a similar information base as the DISC-R, used standardized ratings to record symptom information, and, similar to the DISC-R, was scored by DSM-III-R-based computerized diagnostic algorithms. Subjects were 74 child and adolescent clinic attendees and their adult custodians. RESULTS: Overall, moderate levels of agreement were found between DISC-R and clinician-generated diagnoses; these findings were tempered, however, by the fact that the validation interview was less reliable than the DISC-R. CONCLUSIONS: Although these findings provide preliminary support for the use of the DISC-R, they cast some doubt on the adequacy of clinician-generated diagnoses as validation criteria and suggest that alternate approaches to the assessment of validation should be pursued.

Adolescent↗
PubMed1993

Free radicals, antioxidants, and endothelial cell damage after percutaneous transluminal coronary angioplasty.

BACKGROUND: Oxygen-derived free radicals (ODFRs) and subsequent lipid peroxidation may be responsible for myocardial damage associated with ischaemia/reperfusion after percutaneous transluminal coronary angioplasty (PTCA). These potentially cytotoxic ODFRs are likely to be generated in the plasma, where the primary target organ or cell may be the endothelium. Some of these toxic effects may be limited by the action of antioxidant enzymes such as glutathione peroxidase (GPx). The aim of this study was to determine whether there was evidence of ODFR-mediated damage to the endothelium after PTCA and to examine the roles of lipid peroxides and GPx. METHODS: Serial samples of plasma were obtained at the time of catheter insertion, at the time of balloon inflation, 10 min after inflation, and 60 min after inflation, from 16 patients undergoing PTCA. We measured levels of von Willebrand factor (vWf, a specific product of the endothelium and a marker of damage), thiobarbituric acid reactive substances (TBARS, an indirect measure of the activity of ODFRs in peroxidizing lipoproteins), and the antioxidant GPx. RESULTS: There was a simultaneous peak in the levels of TBARS (P = 0.0096) with a fall in the levels of GPx (P = 0.004) 10 min after balloon deflation. Sixty min after balloon deflation, GPx levels were still reduced (P = 0.005) but there was a rise in levels of vWf (P = 0.038). CONCLUSIONS: Our interpretation of these data is that an early peak in ODFR activity associated with PTCA causes an endothelial injury 1 h after inflation. This may be related to the reduced ability of GPx to scavenge ODFRs.

Adult↗
PubMed1993

Immunolocalization and characterization of the rat analogue of human CD59 in kidney and glomerular cells.

CD59, a potent inhibitor of the human membrane attack complex (MAC) of complement, is present on many different tissues throughout the body. Recently we identified and characterized the rat analogue of CD59 and produced a number of monoclonal antibodies (mAb). We have now used these antibodies to demonstrate, by immunofluorescence microscopy, that rat CD59 was widely expressed in the rat kidney. Staining of renal sections revealed the presence of rat CD59 in abundance in the glomerulus, collecting ducts and distal tubules. Staining was abolished by treatment of sections with phosphatidylinositol-specific phospholipase C (PIPLC). Rat mesangial cells also stained strongly for rat CD59, giving an intensely granular staining pattern. In complement attack experiments the cultured mesangial cells were rendered more susceptible to lysis by rat or human complement after preincubation with the anti-inhibitor mAb. The results demonstrate that the rat analogue of CD59 is present and functionally active in rat renal tissue. The protective effect of CD59 against MAC-mediated tissue injury can now be examined in rat models of human renal disease.

Animals↗
PubMed1993

Release of gelatinase and superoxide from human mononuclear phagocytes in response to particulate Tamm Horsfall protein.

This study describes the in vitro activation of human mononuclear phagocytes by particulate Tamm Horsfall protein (THP). Peripheral blood monocytes phagocytosed THP particles with the accompanying release of superoxide radicals, N-acetyl-beta-D-glucosaminidase, and neutral metalloproteinase. Immunoprecipitation and substrate gel analysis identified the neutral proteinase as a 95-kd gelatinase. A comparison with other particulate ligands highlighted the specificity of the response to THP and showed that the magnitude of the response was comparable with that obtained with lipopolysaccharide (100 micrograms/ml). Parallel studies using peritoneal macrophages resulted in a similar pattern of enzyme release and reactive oxygen species synthesis. THP has been implicated in the pathogenesis of tubulointerstitial nephritis associated with reflux nephropathy. The present study indicates that an inflammatory response initiated by a neutrophil-THP interaction may be extended into a chronic phase via the activation of mononuclear phagocytes. The subsequent release of reactive oxygen metabolites and proteinases may contribute to the tissue damage and fibrosis associated with chronic immune-mediated tubulointerstitial nephritis.

Chemical Precipitation↗
PubMed1993

Human peritoneal mesothelial cells synthesize interleukin-8. Synergistic induction by interleukin-1 beta and tumor necrosis factor-alpha.

The present study demonstrates the synthesis and secretion of the neutrophil-activating peptide/interleukin-8 (IL-8) by cultured human peritoneal mesothelial cells (HPMC) and examines the regulation of its production by other cytokines. Unstimulated HPMC under growth-arrested conditions released IL-8 in a constitutive and time-dependent manner. Stimulation of HPMC with IL-1 beta or TNF-alpha resulted in a time- and dose-dependent IL-8 generation; after 24 hours the levels induced by IL-1 beta and TNF-alpha (both at 1000 pg/ml) were (mean +/- SEM, n = 5) 101 +/- 26.6 (z = 2.023; P < 0.01) and 35 +/- 8.09 (z = 2.023; P < 0.01) respectively. This release was inhibited following coincubation with the relevant anti-cytokine antibody or preincubation with either cycloheximide or actinomycin D. Treatment of HPMC with IL-1 beta or TNF-alpha resulted in increased levels of IL-8-specific mRNA. Stimulation of HPMC with combinations of IL-1 beta and TNF-alpha resulted in a synergistic increase in IL-8 release. This effect was significant at combined doses of IL-1 beta (50 pg/ml) and TNF-alpha (500 pg/ml) and above, when the release of IL-8 was 88 +/- 27% above the additive IL-8 release values (z = 2.201; P < 0.01). Western blot analysis using specific anti-IL-8 antibody demonstrated the presence of two major immunoreactive bands between 9 and 10 kd, in HPMC culture supernatants. These data demonstrate that HPMC synthesize IL-8 and that its release can be regulated as a result of induction of mRNA expression and de novo protein synthesis by other cytokines.

Base Sequence↗
PubMed1992

Involvement of extracellular-matrix-degrading metalloproteinases in rabbit aortic smooth-muscle cell proliferation.

We investigated the influence of two structurally unrelated inhibitors of matrix-degrading metalloproteinases, Ro 31-4724 and Ro 31-7467, on the primary proliferation of smooth-muscle cells from rabbit aortic explants. Both agents inhibited proliferation in a concentration-dependent manner, but did not affect cell viability. Smooth-muscle cells grown out from explants secreted 95 kDa and 72 kDa gelatinase enzymes that were also inhibited in a concentration-dependent manner by Ro 31-4724 and Ro 31-7467. Interstitial collagenase and stromelysin were not detected. We conclude that metalloproteinases are likely to be involved in the initiation of smooth-muscle proliferation.

Animals↗
PubMed1992

High-performance liquid chromatography of oligosaccharide alditols and glycopeptides on a graphitized carbon column.

The chromatographic behaviour of oligosaccharide alditols and glycopeptides containing neutral and acetamido sugars and sialic acid has been investigated on a HyperCarb porous graphitised carbon column. The alditols were substantially retained and could be eluted in 0-25% acetonitrile-0.05% trifluoroacetic acid in 0.05% aqueous trifluoroacetic acid between 3-30 min for mono- to hexasaccharides. Elution patterns were based on both size, charge and linkage such that isomeric compounds could be separated from each other.

Amino Acid Sequence↗
PubMed1992

Molecular characterization of a low-molecular-mass matrix metalloproteinase secreted by glomerular mesangial cells as PUMP-1.

A polymerase chain reaction (PCR)-based homology cloning strategy was used to define the spectrum of stromelysin-like matrix metalloproteinases (MMPs) synthesized by cultured glomerular mesangial cells (MC). Using this technique, cDNAs encoding an unusual, truncated member of the MMP family, punctuated (putative) metalloproteinase (PUMP-1), were exclusively isolated. Incubation with the cytokines interleukin 1 and tumour necrosis factor increased the abundance of PUMP-1 mRNA in mesangial cells. The mesangial PUMP-1 mRNA is processed in a tissue-specific manner, yielding a transcript containing repeated 3'-untranslated region ATTTA motifs commonly found in cytokines with limited mRNA stability. Polyclonal antibodies prepared against the C-terminal region of the PUMP-1 protein documented release of this enzyme by cultures of cytokine-stimulated MC and permitted identification of PUMP-1-expressing mesangial cells within clinical biopsy specimens of acute glomerulonephritis. These findings represent new molecular and clinical evidence that non-malignant cells process and secrete this unusual member of the MMP family in a cytokine-mediated, tissue-specific manner. Mesangial synthesis of PUMP-1 may contribute to the progression of injury during glomerular inflammatory states.

Amino Acid Sequence↗
PubMed1992

The Structured Clinical Interview for DSM-III-R (SCID). II. Multisite test-retest reliability.

A test-retest reliability study of the Structured Clinical Interview for DSM-III-R was conducted on 592 subjects in four patient and two nonpatient sites in this country as well as one patient site in Germany. For most of the major categories, kappa s for current and lifetime diagnoses in the patient samples were above .60, with an overall weighted kappa of .61 for current and .68 for lifetime diagnoses. For the nonpatients, however, agreement was considerably lower, with a mean kappa of .37 for current and .51 for lifetime diagnoses. These values for the patient and nonpatient samples are roughly comparable to those obtained with other structured diagnostic instruments. Sources of diagnostic disagreement, such as inadequate training of interviewers, information variance, and low base rates for many disorders, are discussed.

Diagnosis, Computer-Assisted↗
PubMed1992

Proteinases and glomerular matrix turnover.

The mesangial cell MMPs and their inhibitor may represent proteins through which biological modifiers such as cytokines and growth factors can control and influence the organization of the glomerulus. At the present we can only speculate on their exact function in glomerular disease. They could conceivably play a role in glomerular conditions where mesangial hypercellularity and cytoplasmic interposition between the endothelium and the basement membrane are frequent occurrences, and in which cytokine-enhanced synthesis of matrix-degrading enzymes could result in severe structural damage. A number of glomerular diseases such as diabetic nephropathy are characterized by the accumulation of glomerular matrix proteins. This could be explained by the inappropriate expression of intrinsic mesangial cell MMPs or TIMP. Further investigation of these proteins in experimental models of glomerular disease or in situ hybridization studies using the available probes promises to be a rewarding area of research during the next few years. For these studies the availability of rTIMP and recent developments in the design of synthetic inhibitors of MMPs may allow more searching investigations into the role of MMP in the pathophysiology of glomerular disease.

Amino Acid Sequence↗