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Biomedical subjects

P Anderson

Publications and source records attributed to P Anderson.

At least 289 records · Page 16Linked to original sources
PubMed1992

Increased rate of tuberculin skin test conversion among workers at a university hospital.

OBJECTIVES: To summarize the results of an investigation of increased rates of tuberculin skin test conversion in employees at a university hospital. DESIGN: The results of annual tuberculin skin tests performed on all 1,845 hospital employees from 1986 to 1991 were reviewed. SETTING: A 450-bed acute tertiary care university hospital. RESULTS: The rate of tuberculin skin test conversion was 0.35% (standard deviation +/- 0.15) from 1986 to 1989 and increased to 1.7% during 1991. Investigation revealed deviations from the Centers for Disease Control (CDC) guidelines for tuberculosis control, which included the failure to consider tuberculosis as a probable cause of community-acquired pneumonia and the failure to initiate isolation precautions when tuberculosis was suspected. CONCLUSIONS: The epidemic appeared to be secondary to delays in diagnosis and isolation of patients with pulmonary tuberculosis. Future control measures should include isolation of all hospital patients admitted with pneumonia until tuberculosis has been excluded.

Centers for Disease Control and Prevention, U.S.↗
PubMed1992

Signaling function of reconstituted CD16: zeta: gamma receptor complex isoforms.

Natural killer cells express an Fc receptor for IgG (CD16) in association with disulfide-linked dimers composed of two homologous subunits: the zeta chain of the T cell antigen receptor complex and the gamma chain of the mast cell/basophil Fc receptor for IgE. The ability of zeta and gamma to transduce CD16-mediated activation signals was compared by reconstituting distinct CD16 receptor isoforms composed of various combinations of zeta- and gamma-containing dimers. Stably transformed non-hematopoietic and hematopoietic cell lines were established that expressed chimeric molecules comprising the extracellular domain of CD16 joined to the transmembrane and intracellular domains of zeta or gamma. Reconstituted CD16 receptor complexes triggered Ca2+ influx, tyrosine phosphorylation, and IL-2 production in stable transformants of the Jurkat T cell line. However, cross-linking of the CD16/gamma chimera induced a specific pattern of tyrosine phosphorylation and was more efficient at signal transduction than a CD16, zeta-zeta complex, suggesting that zeta and gamma cytoplasmic domains may be coupled to distinct tyrosine kinase pathways that differentially regulate CD16-mediated activation signals. By contrast, both CD16/zeta and CD16/gamma chimeric molecules were not functional in stable transformants of the fibroblast Chinese Hamster Ovary cell line, indicating a requirement for downstream signaling components present in hematopoietic cells. Finally, the zeta transmembrane domain appears to preferentially associate with CD16 rather than the CD3:TCR complex, suggesting that a hierarchy of molecular interactions governs NK and T cell differentiation.

Animals↗
PubMed1992

The effect of general practitioners' advice to heavy drinking men.

The objective of the study was to determine the effectiveness of advice from general practitioners to heavy drinking men (consuming 350-1050 grams of alcohol per week) to reduce their alcohol consumption. One hundred and fifty-four men recruited from eight general practices were allocated randomly to treatment and control groups. Men in the treatment group received advice from their own general practitioner. At one year follow-up, when analyzed according to intention to treat, the treatment group had reduced their consumption by an excess of 65 grams of alcohol per week when compared with the control group (p less than 0.05). General practitioners should be recommended to screen for alcohol consumption amongst their patients and to give advice to those found to be at risk because of their drinking.

Adult↗
PubMed1992

Subsurface demineralization in dental enamel and other permeable solids during acid dissolution.

Subsurface demineralization of dental enamel during acid dissolution has been reported many times, but its cause remains obscure. At first, the phenomenon was thought to result from the physical structure of enamel. More recent studies have shown that subsurface demineralization occurs in other permeable solids, indicating that there must be more fundamental factors involved in this curious effect. In order for this phenomenon to be investigated, dissolution experiments were carried out by means of real-time scanning microradiography in various systems, including enamel, or aggregates of hydroxyapatite (calcium, strontium, or barium), or hydroxides (calcium or magnesium). These were chosen to discriminate between effects of structure and composition. It was found that it was not possible for the demineralization observed in these systems to be attributed to a common feature. From this, it is concluded that subsurface demineralization in enamel and other mineralized tissues should not be ascribed to a single cause.

Acetates↗
PubMed1992

Improved therapeutic index of carboplatin plus cyclophosphamide versus cisplatin plus cyclophosphamide: final report by the Southwest Oncology Group of a phase III randomized trial in stages III and IV ovarian cancer.

PURPOSE: To compare cisplatin-cyclophosphamide versus carboplatin-cyclophosphamide as primary chemotherapy for stage III (suboptimal) and stage IV ovarian cancer. PATIENTS AND METHODS: Three hundred forty-two patients were randomly assigned to treatment with six courses of intravenous (i.v.) cisplatin 100 mg/m2 plus i.v. cyclophosphamide 600 mg/m2, or i.v. carboplatin 300 mg/m2 plus i.v. cyclophosphamide 600 mg/m2. RESULTS: The estimated median survivals were 17.4 and 20.0 months for the cisplatin and carboplatin study arms, respectively. The null hypothesis of a 30% survival superiority with the cisplatin arm was rejected at the P = .02 level. Clinical response rates were 52% for the cisplatin arm and 61% for the carboplatin arm. Pathologic complete response rates were similar for both study arms. There was less thrombocytopenia on the cisplatin arm (P less than .001); however, there was less nausea and emesis (P less than or equal to .001 for courses 1 to 5), renal toxicity (P less than .001), anemia (P = .01), hearing loss (P less than .001), tinnitus (P = .01), neuromuscular toxicities (P = .001), and alopecia (P less than .001) on the carboplatin arm. CONCLUSION: Carboplatin-cyclophosphamide proved to have a significantly better therapeutic index than cisplatin-cyclophosphamide in patients with stage III (suboptimal) and stage IV ovarian cancer.

Adult↗
PubMed1992

Structure and function of the CD16:zeta:gamma complex expressed on human natural-killer cells.

Natural-killer (NK) cells are large granular lymphocytes involved in host defense against tumor cells and virally-infected cells. In addition to natural cytotoxicity, NK cells can effect antibody-dependent cytotoxicity mediated by CD16 (Fc gamma RIIIA alpha). It has recently been shown that CD16 is associated with disulfide-linked dimers composed of 2 homologous sub-units, zeta and gamma. These transducing molecules are also associated with other multimeric cell-surface receptors such as the T-cell antigen receptor (CD3:TCR) complex (zeta and gamma) and the high-affinity Fc receptor for IgE (Fc epsilon RI) expressed on basophils and mast cells (gamma). These results show that distinct cell-surface receptors utilize common transducing sub-units, and emphasize the homology between the CD16, Fc epsilon RI and CD3:TCR complexes. However within the lymphoid cells, the gamma-gamma homodimer is preferentially expressed in NK cells and cytotoxic T cells, suggesting that specific combinations of these transducing dimers might sub-serve distinct signal-transducing functions, and contribute to lymphocyte heterogeneity.

CD3 Complex↗
PubMed1992

Evidence of cytotoxic T-cell destruction of epidermal cells in human graft-vs-host disease. Immunohistology with monoclonal antibody TIA-1.

A newly described mouse monoclonal IgG1 antibody, TIA-1, binds serine esterase-positive granule membranes of cytotoxic human T cells and is a candidate for an effector molecule involved in T-cell cytolytic mechanisms analogous to those of the perforin system. We performed immunohistologic studies on frozen human skin (n = 5) and lip (n = 21) sections as well as on control frozen sections of tonsils, purified cytolytic T (CD8) cells, and B cells using an indirect immunoperoxidase system. We found a strong association of TIA-1+ cells with CD8+ cells invading the epidermis in lip and skin lesions of graft-vs-host disease in human marrow allograft recipients, as well as a sharp geographic association of TIA+ lymphocytes with CD8+ regions in human tonsil sections. Double staining of CD8 and TIA-1 antigens with fluorescein isothiocyanate and Texas red confirmed that 80% to 90% of the CD8 cells were TIA-1+ in the epidermal infiltrates. Leu-7 activity (natural killer cell) was minimal and found in only three of 17 lip biopsy specimens. These data provide new evidence that direct cytolytic attack by donor T lymphocytes is the mechanism of epithelial target cell killing in human graft-vs-host disease.

Adolescent↗
PubMed1991

Structural similarity between Fc receptors and T cell receptors. Expression of the gamma-subunit of Fc epsilon RI in human T cells, natural killer cells and thymocytes.

The TCR complex is composed of a clonotypic heterodimer (Ti alpha:beta or gamma:delta) noncovalently associated with the CD3 complex (gamma, delta, and epsilon), and with one or more disulfide-linked dimers whose components are designated zeta and eta. zeta and eta are alternative transcripts of a common gene and are structurally related to the gamma-subunit of the FcR for IgE expressed on mast cells and basophils (Fc epsilon RI). Recent evidence suggests that gamma can also be expressed in natural killer cells and in a murine cytotoxic T cell line, CTLL. Because zeta, eta, and gamma have the potential to join together to form disulfide linked homo- and heterodimers, it has been postulated that alternative dimeric forms composed of these zeta-related subunits might subserve unique signal transducing functions in hematopoietic cells. We have used mAb reactive with zeta and gamma to systematically examine the expression of these zeta-related dimers in human T cells, NK cells, and thymocytes. Our results show that each cell type expresses characteristic combinations of zeta-related homo- and hetero-dimers, and are therefore consistent with the possibility that these subunits contribute to the functional heterogeneity of lymphocyte subsets.

Antibodies, Monoclonal↗
PubMed1991

Discordant gene and surface expression of the T-cell receptor/CD3 complex in adult T-cell leukemia cells.

Cell surface expression of the T-cell receptor (TCR)/CD3 complex on the cells from 11 acute type adult T-cell leukemia (ATL) and 4 lymphoma type ATL patients was examined by flow cytometry. Cells from 10 of 11 acute ATL patients were TCR alpha beta+ and CD3+, and their mean fluorescence intensities were low (TCR alpha beta, 25.3-84.6; CD3, 22.8-87.8). Cells from two of four lymphoma type ATL did not express this complex, and the other two were CD3+, TCR alpha beta-. In contrast, the mean fluorescence intensity of the TCR/CD3 complex in cells from a patient with T4 chronic lymphocytic leukemia was not low (TCR alpha beta, 129.9; CD3, 117.1). mRNA expressions of the TCR alpha, beta, and CD3 gamma, delta, epsilon, and zeta chains were examined by Northern blots. ATL cells from two acute and two lymphoma types expressed amounts of this complex equal to or greater than those expressed by T4 chronic lymphocytic leukemia. CD3 delta and TCR beta mRNA in ATL and T4 chronic lymphocytic leukemia cells were equally stable to actinomycin D treatment. The synthesis of CD3 zeta protein by ATL cells was detected by Western blotting assay. On the basis of these findings, we discuss the possible involvement of the TCR/CD3 complex in activation of ATL cells.

Adult↗
PubMed1991

A polyadenylate binding protein localized to the granules of cytolytic lymphocytes induces DNA fragmentation in target cells.

Cytolytic lymphocytes (CTLs) are characterized by their inclusion of cytoplasmic granules containing effector molecules such as perforin and the serine proteases. Here we describe the cDNA cloning and functional characterization of two related isoforms of a cytolytic granule protein designated TIA-1. Sequence analysis reveals that the 40 kd TIA-1 isoform (rp40-TIA-1) is structurally related to the poly(A)-binding proteins, possessing three RNA-binding domains and a carboxy-terminal, glutamine-rich auxiliary domain. The 15 kd TIA-1 isoform, the major species present in cytolytic granules, appears to be derived from the carboxy-terminal auxiliary domain of rp40-TIA-1 by proteolytic processing. Both natural and recombinant TIA-1 were found to induce DNA fragmentation in digitonin permeabilized thymocytes, suggesting that these molecules may be the granule components responsible for inducing apoptosis in CTL targets.

Amino Acid Sequence↗