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Biomedical subjects

D Lo

Publications and source records attributed to D Lo.

116 records · Page 7Linked to original sources
PubMed1986

Functions of purified L3T4+ and Lyt-2+ cells in vitro and in vivo.

The expression of L3T4 and Lyt-2 cell surface molecules separates T cells into two broad, non-overlapping subsets: typical T helper cells are L3T4+ Lyt-2- whereas most T killer cells and their precursors are L3T4- Lyt-2+. This review compares highly purified populations of unprimed L3T4+ and Lyt-2+ cells for their capacity to respond to class I vs. class II H-2 alloantigens. Various parameters are considered, including generation of mixed lymphocyte reactions (MLR) and cell mediated lympholysis (CML) in vitro, proliferative responses in irradiated mice, graft-versus-host reactions and skin allograft rejection. In all of these assays the two T cell subsets exhibit marked specificity in their response to H-2 alloantigens, L3T4+ cells responding only to class II and not class I differences and Lyt-2+ cells showing reciprocal specificity. Contrary to current dogma, the bulk of the evidence suggests that primary responses of Lyt-2+ cells do not depend on exogenous help provided by other T cells.

Animals↗
PubMed1982

The role of postnatal age and magnesium on parathyroid hormone responses during "exchange" blood transfusion in the newborn period.

One hundred and eight "exchange" blood transfusions were done on 61 newborn infants. Baseline serum PTH concentrations and the PTH rise in response to citrate-induced hypocalcemia were studied. Baseline PTH values increased with postnatal age, particularly after the first three days of life. The acute response of PTH to citrate-induced hypocalcemia appears within ten minutes following the initiation of exchange transfusion and was shortlived in spite of further decline of serum ionized calcium. The dominant effect of postnatal age over gestational age was demonstrated: postnatally older but gestationally less mature infants exhibited greater responsiveness than postnatally younger, but gestationally more mature, infants. The PTH response during exchange transfusion was blunted in hypomagnesemic infants. Since lower serum magnesium concentrations were also present during the first three days of life, a separate effect of serum magnesium concentrations on parathyroid responsiveness cannot be ruled out in this study.

Age Factors↗
PubMed1976

Cryptococcosis in the Northern Territory.

This report represents a review of cryptococcosis in the Northern Territory from 1957 to 1975. There were 26 cases over a 19-year period; 25 of these were in full-blooded Aborigines. The disease occurred throughout the rural areas of the Territory as isolated cases. There were 24 cases of cryptococcal meningitis and only two with solitary lung involvement. The overall mortality was 50%. In all five untreated cases the disease was fatal. There were eight deaths among the 20 patients receiving chemotherapy, a mortality of 40%. Lung resection was performed in six cases of localized pulmonary cryptococcosis. The outcome for these was excellent.

Adolescent↗
PubMedDate not supplied

Identity of cells that imprint H-2-restricted T-cell specificity in the thymus.

The thymus has two important roles in controlling the specificity of T lymphocytes. First, T cells differentiating in the thymus are rendered tolerant of 'self' antigens, particularly antigens encoded by the major histocompatibility complex, the H-2 complex in mice. Second, the thymus imbues T cells with the property of H-2-restricted recognition of antigen, that is, the capacity of T cells to react with foreign antigens presented in association with self H-2 gene products. Until recently it has generally been assumed that self-tolerance and H-2-restricted specificity both reflect early T-cell contact with self H-2 determinants expressed on thymic epithelial cells. Recent evidence suggests, however, that intrathymic cells of the macrophage/dendritic cell (Mphi/DC) lineage also have a role in shaping T-cell specificity. In particular, it has been found that the tolerance to graft-type H-2 determinants which normally ensues when T cells differentiate in an H-2-different thymus fails to occur when the thymus is pretreated with deoxyguanosine (dGuo), a procedure that selectively destroys Mphi/DC but spares epithelial cells. In contrast to these findings on tolerance induction, evidence is presented here that dGuo-treated thymus grafts do imprint T cells with H--2-restricted specificity for antigen. It appears, therefore, that induction of tolerance and H--2 restriction are controlled by different cells in the thymus.

Animals↗
PubMedDate not supplied

Detection of the tumour suppressor gene p53 in nasopharyngeal carcinoma in Hong Kong Chinese.

This study has investigated the expression of the p53 tumour suppressor gene in 41 cases of primary nasopharyngeal carcinomas (NPC) using the p53 monoclonal antibody BP53-12. Moderate p53 expression was found in 54% and strong expression in 12% of the specimens. There was no correlation between p53 expression and any of the clinicopathological parameters or survival. Surprisingly, three research groups have investigated p53 mutations in NPC and found no fresh tumour specimens to contain p53 mutations in exons 4-8 of the gene. It may be argued that as p53 overexpression has been demonstrated in 70% of the patients investigated in this study, that the mutations lie outside the 4-9 exon region. We are in the process of testing this hypothesis.

Adult↗