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Biomedical subjects

R Black

Publications and source records attributed to R Black.

At least 73 records · Page 4Linked to original sources
PubMed1991

Human keratinocytes produce but do not process pro-interleukin-1 (IL-1) beta. Different strategies of IL-1 production and processing in monocytes and keratinocytes.

Keratinocytes comprise the majority of cells in the epidermis, the interleukin-1 rich layer of tissue contiguous with the outside world. Keratinocytes produce IL-1 alpha and beta mRNA in vitro, but only IL-1 alpha biological activity has been identified in keratinocyte cultures. In contrast, monocytes secrete biological activities attributable to both species of IL-1. Using several monoclonal antibodies to IL-1 beta, significant amounts of IL-1 beta protein could be found in keratinocyte cultures; all of this immunoreactive IL-1 beta was in the 31-kD form. This latent cytokine has been shown to bind inefficiently to the IL-1 receptor and to be (in relative terms) biologically inactive. Chymotrypsin cleaves 31-kD IL-1 beta at Tyr 113-Val 114, generating an 18-kD IL-1 species with activity equivalent to the authentic mature IL-1 beta (NH2-terminal Ala 117). Treatment of 31-kD keratinocyte IL-1 beta with chymotrypsin also generated an 18-kD molecule and significant IL-1 activity. Monocytes contain an IL-1 convertase enzyme that cleaves the IL-1 beta promolecule at Ala 117. We demonstrate here that keratinocytes do not contain such an IL-1 convertase activity, nor do they contain any activity capable of productively processing 31-kD IL-1 beta into a biologically active form. These data suggest that keratinocytes (and other non-bone marrow-derived cells) produce IL-1 beta in an inactive form that can be processed only after leaving the cell.

Blotting, Western↗
PubMed1991

The proteolytic activation of interleukin-1 beta.

Interleukin-1 beta (IL-1 beta) is released from an inactive precursor by a proteolytic cleavage. A monocytic protease has been identified that appears to be involved in the physiological activation of this cytokine. Two situations have been found in which precursor IL-1 beta exists without the monocytic processing enzyme, and in these cases other proteases, such as neutrophil elastase, cathepsin G and cathepsin L, may be involved in generating the active cytokine.

Cell Line↗
PubMed1990

Somatic growth in infants receiving prolonged caffeine therapy.

We have evaluated the longitudinal growth of 28 premature infants who had been treated by prolonged caffeine therapy (mean: 23.8 weeks). Routine follow-up included at least 5 physical examinations with measurement of length, weight and head circumference at the beginning of caffeine therapy, at mid therapy, at the end of the therapy and at 3 and 6 months after therapy. The distribution of the infants on the growth curves according to weight, length and head circumference showed a regular increase in growth parameters. Analysis of variance was highly significant at p less than 0.0001. We conclude that long term caffeine treatment does not adversely influence growth parameters, at least during early infancy.

Anthropometry↗
PubMed1990

Breast-feeding and diarrheal morbidity.

This study used a unique longitudinal survey of more than 3000 mother-infant pairs observed from pregnancy through infancy. The sample is representative of infants from the Cebu region of the Philippines. The sequencing of breast-feeding and diarrheal morbidity events was carefully examined in a longitudinal analysis which allowed for the examination of age-specific effects of feeding patterns. Because the work controlled for a wide range of environmental causes of diarrhea, the results can be generalized to other populations with some confidence. The addition to the breast-milk diet of even water, teas, and other nonnutritive liquids doubled or tripled the likelihood of diarrhea. Supplementation of breast-feeding with additional nutritive foods or liquids further increased significantly the risk of diarrhea; most benefits of breast-feeding alone or in combination with nutritive foods/liquids became small during the second half of infancy. Benefits of breast-feeding were slightly greater in urban environments.

Breast Feeding↗
PubMed1989

Idiopathic constipation by colonic dysfunction. Relationship with personality and anxiety.

The personality of two groups of constipated women (by delayed colonic transit or by colonic inertia) was compared to that of two control groups of arthritic patients (rheumatoid or degenerative disease) with the Minnesota Multiphasic Personality Inventory (MMPI). All subjects suffered from chronic pain. Constipated women were found to have significantly higher scores on the hypochondria, hysteria, control, and low back pain scales and a lower score on the masculinity-femininity scale. Discriminant analysis permitted us to sort out constipated from arthritic patients in 83% of the cases, on the basis of only the personality data. In women with constipation by delayed colonic transit, multiple regression analysis demonstrated a close link (r = 0.90; P less than 0.001) between transit time in the ascending colon and levels of anxiety. It is concluded that women with constipation of colonic origin have a different pattern of personality than arthritic women and that severe constipation may play the role of a defense mechanism, where psychophysiologic responses to life stresses replace normal emotional reactions.

Adolescent↗
PubMed1988

Lectin histochemistry of the liver in biliary disease, following transplantation and in cholangiocarcinoma.

Evidence is accumulating that there are changes in the expression of antigens on biliary epithelium in early primary biliary cirrhosis and graft rejection. If any of the biliary diseases including rejection are associated with specific alterations in biliary glycoprotein structure, lectin histochemistry could be useful for detecting these abnormalities. Lectin histochemistry, using a panel of five lectins with differing carbohydrate specificities, was therefore performed on liver biopsies from patients with primary biliary cirrhosis, sclerosing cholangitis, cholangiocarcinoma, liver transplantation, extrahepatic biliary obstruction and normal liver. Reproducible high-quality lectin histochemistry was obtained on formalin-fixed paraffin-embedded tissue. In normal liver wheat germ agglutinin selectively bound to Kupffer cells, Griffonia simplicifolia II bound to hepatocytes, peanut agglutinin (PNA) bound to portal tract macrophages and liver capsule, and Ulex europaeus I (UEA I) bound to endothelium. Bile ducts were variably bound by all these lectins and soy bean agglutinin. In all the cholestatic biopsies PNA identified 'activated' Kupffer cells but there was no alteration in lectin binding specific to any of the benign conditions studied. Cholangiocarcinoma cells bound PNA and UEA I, so UEA I binding should not be regarded as specific for tumours of endothelial origin.

Adenoma, Bile Duct↗
PubMed1988

Use of lectin histochemistry in pancreatic cancer.

Lectin peroxidase histochemical analysis was carried out on pancreatic tissue from patients with pancreatic carcinoma and chronic pancreatitis and from subjects with normal pancreas to find a tumour specific pattern of lectin binding that would aid histological and cytological diagnosis. There were striking differences between the lectin binding characteristics of the different cell types in the normal pancreas. Acinar cells were uniformly positive for binding with wheat germ agglutinin and soy bean agglutinin while islet cells were usually negative for these lectins. Ulex europaeus I lectin however, was found not to be specific for endothelium, showing positivity also for acinar and ductal tissue. Griffonia simplicifolia II lectin was found to be highly specific for ductal epithelium, and because of this was tested in a hamster pancreatic cancer model where it was not specific for ductal epithelium, reflecting differing carbohydrate expression in the hamster pancreas. Pancreatic carcinomas and chronic pancreatitis bound all five lectins without any qualitative distinction from each other or from normal pancreatic tissue, but there was increased intensity of peanut agglutinin binding to secreted mucins in pancreatic carcinoma, which may be of potential use in radiolabelled lectin scanning.

Animals↗
PubMed1987

Genetic variants of C2 muscle cells that are defective in synthesis of the alpha-subunit of the acetylcholine receptor.

We have analyzed two genetic variants of C2 muscle cells that have reduced levels of binding activity for alpha-bungarotoxin and have found that both synthesize only low levels of the alpha-subunit of the acetylcholine receptor. In both variants the uptake of 22Na in response to carbachol is diminished in proportion to the reduction in toxin-binding activity. In addition, the kinetic and sedimentation properties of the residual toxin-binding activity in both is indistinguishable from that seen in wild-type cells. Immunoblotting experiments on extracts of the variants using subunit-specific antibodies to alpha- and beta-subunits of the acetylcholine receptor demonstrated that the beta-subunit was present, but failed to detect alpha-subunit. In both variants, the amount of alpha-subunit accumulated after a 5-min period of labeling with [35S]methionine was reduced by over 90%, leading to the conclusion that the alpha-subunit is synthesized at greatly reduced rates. Northern blot and S1 nuclease analysis showed no differences between the alpha-subunit mRNA in wild-type and variant cells.

Animals↗
PubMed1987

Interferon-gamma induces altered oncogene expression and terminal differentiation in A431 cells.

In tumor cell lines in which oncogene expression is abnormal, modulation of the expression of the oncogene (myc, src, or ras) by interferons (IFNs) has been observed concurrently with cell growth inhibition or phenotypic reversion. Oncogene expression has also been reported to vary during the differentiation of several neoplastic cell lines. Treatment of monolayer cultures of A431, a human epidermoid carcinoma cell line, with IFN-gamma resulted in rapid morphological alterations and cell death not seen with either IFN-alpha or IFN-beta. These changes were accompanied by elevated expression of mRNA's for p21 (the c-ras gene product) and the epidermal growth factor receptor as well as increases in the biosynthetic rate of their respective proteins. These effects likewise appeared to be specific for IFN-gamma. Growth inhibition by IFN-gamma was also observed when A431 cells were grown in a three dimensional in vitro culture system. Immunohistochemical staining of these "tumoroids" with a differentiation specific, anti-keratin antibody indicated that IFN-gamma enhanced expression of this keratin. This observation suggests that the killing by IFN-gamma of A431 cells may result from an acceleration of terminal differentiation.

Animals↗
PubMed1986

Oligonucleotide mapping of viral ribonucleic acid as an aid in identifying laboratory contaminants of influenza virus.

Influenza viruses that were suspected to be laboratory contaminants of clinical specimens because they had antigenic properties identical to standard laboratory strains were examined by T1 oligonucleotide mapping of virion ribonucleic acid. For the three instances reported herein involving thirteen viruses, it was concluded that laboratory contamination had occurred, since in each instance, a standard laboratory strain that had been used in the clinical laboratory before the isolation, had an oligonucleotide map that was either identical to or very similar to those of the "isolates," there was no evidence of spread of these viruses, and in cases where serum samples were available, no serologic evidence existed of infection by these virus strains.

Clinical Laboratory Techniques↗
PubMed1985

Healing of spontaneous periodontal defects in dogs treated with xenogeneic demineralized bone.

This study was undertaken to histologically, clinically and radiographically evaluate the sequence of healing following implantation of bovine demineralized bone powder (DBP) into severe, spontaneous periodontal defects in beagle dogs. Eight dogs with documented severe periodontitis were treated surgically following initial debridement. One quadrant in each arch was treated with conventional flap surgery and the others were treated with surgery followed by DBP implantation. Animals received postoperative debridement and clinical and radiographic evaluation. Two dogs were sacrificed at 1, 3, 6 or 12 months postoperatively, and the jaws were evaluated histologically. Clinically, DBP was well tolerated by recipients. No evidence of localized inflammatory response or delayed hypersensitivity reaction was noted. Significant reductions in gingival inflammation were noted in both experimental and control sites at 1 month postoperatively compared to preoperative scores. Equivalent periodontal pocket reduction was noted between test and experimental sites and remained significant at 12 months. Radiographically, no differences were noted in the rate of bone loss between control and test sites. Histologic evaluation demonstrated the presence of DBP at 1 month following implantation, but the material was replaced with new bone by the next sacrifice period. Periodontal ligament fibers of standard orientation were seen extending from DBP-induced bone to the root surface by 1 month after implantation. An intact epithelial attachment appeared to be present 1 month after the implantation of DBP. No differences in root surfaces were detected between test and control groups. Ankylosis was a rare finding, noted equally between test and control sites. DBP did not appear to predispose to external root resorption. In later stages, histologic evidence of advancing periodontitis was noted equally in both control and experimental groups. While DBP successfully induced new bone formation, the inability to adequately maintain the periodontal tissues due to bacterial accumulation in this model combined with recurrent pocket formation, precluded any conclusion regarding long-term advantage. Based on these findings, clinical trials of this or similar materials are recommended.

Alveolar Process↗