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Biomedical subjects

D White

Publications and source records attributed to D White.

At least 307 records · Page 17Linked to original sources
PubMed1985

Lymphocyte function in human bone marrow. II. Characterization of an interleukin 2-sensitive T precursor-cell population.

In the present study of human bone marrow lymphocytes, we analyze a newly recognized population of T suppressor-cell precursors which are found in marrow only and which have the potential to inhibit immunoglobulin (Ig) production in vitro. Following exposure to interleukin 2 (IL2), suppressor precursors acquire E receptor, T3 determinants, suppressor function, and lectin responsiveness. To distinguish this population within the framework of T-cell ontogeny, it was compared to a previously described population of thymus-dependent helper T-cell precursors which express helper function following exposure to thymus-derived mediators. The two populations are completely distinct and can be separated on density gradients. Suppressor precursors expressed T8 and TAC (IL2-receptor) antigens prior to in vitro induction with IL2. The thymic hormone-dependent cells expressed T4 but not T8 or TAC determinants. In two patients with severe combined immunodeficiency disease (SCID), IL2-responsive precursor cells appeared only late after thymus epithelium transplantation, perhaps best explained by a model in which thymus-dependent differentiation pathways precede, induce, or seed pathways of extra-thymic T-cell differentiation. The large pool size of over 10(11) suppressor and helper precursor cells present in adult bone marrow suggests that these populations may play an important role in immune homeostasis.

Adult↗
PubMed1985

Superiority of two-dimensional measurement of aortic vessel diameter in Doppler echocardiographic estimates of left ventricular stroke volume.

Attempts to measure left ventricular stroke volume utilizing the Doppler aortic flow method have found varying correlations between invasive thermodilution and non-invasive Doppler methods. Because stroke volume is the product of the Doppler flow velocity integral (that is, the area under the flow velocity curve) and the cross-sectional area of the vessel through which blood flows, both variables are potential sources of error. Previous studies have shown that the Doppler flow velocity integral can be measured with acceptable reproducibility in the ascending aorta. Consequently, in this study an attempt was made to determine empirically the optimal method for measuring aortic diameter and area. The diameter of the ascending aorta was measured utilizing four M-mode and seven two-dimensional echocardiographic conventions. Doppler aortic flow velocity patterns were recorded with a 2.25 MHz M-mode echocardiographic transducer from the suprasternal notch by mapping the ascending aorta until aortic peak flow velocity was recorded. In 19 adult patients undergoing cardiac catheterization for clinical indications, Doppler stroke volume estimates utilizing the various echocardiographic conventions for measuring aortic root diameter and area were compared with simultaneous measurements of stroke volume by the thermodilution technique. The best correlation (r = 0.87) with thermodilution stroke volume was obtained by estimating aortic area from the two-dimensional parasternal long-axis images with the aortic dimension measured distal to the aortic sinuses from the inner to inner wall. The data were related by the equation: Thermodilution stroke volume = (0.73) X (two-dimensional Doppler stroke volume) + 17 cc.(ABSTRACT TRUNCATED AT 250 WORDS)

Aorta↗
PubMed1985

Carbon dioxide laserbrasion for treatment of adenoma sebaceum in tuberous sclerosis.

Adenoma sebaceum is a disfiguring facial deformity that constitutes part of the multiple system involvement in tuberous sclerosis. Three affected patients have been treated with carbon dioxide "laserbrasion," which has resulted in a long-lasting improvement without scarring or recurrence. Tuberous sclerosis is described, and the CO2 technique is discussed.

Adenoma↗
PubMed1985

Energy-dependent cell cohesion in myxobacteria.

Cohesion in the myxobacterium Stigmatella aurantiaca was characterized. Two classes of cohesion were revealed, termed class A and class B. Class A cohesion is a characteristic of vegetative cells grown in tryptone or casitone (Difco Laboratories, Detroit, Mich.), whereas class B cohesion requires the addition of calcium ion for induction. Class A cohesion occurs in the presence of any cation and is temperature independent. Class B cohesion requires the presence of a cation in the calcium group and is energy dependent. We conclude that S. aurantiaca responds to calcium ion by synthesizing the molecular components of a system of cell cohesion (class B) and that the functioning of this system requires the expenditure of metabolic energy.

Calcium↗
PubMed1985

Morphogenesis of Stigmatella aurantiaca fruiting bodies.

Scanning electron micrographs of intermediate stages of fruiting body formation in the myxobacterium Stigmatella aurantiaca suggest that fruiting body formation can be divided into several stages distinguishable on the basis of the motile behavior of the cells. Aggregates formed at sites where cells glide as groups in circles or spirals. Thus, each aggregate was surrounded by a wide band of cells. Several streams of cells were pointed toward and connected to the wide band of cells at the base of the aggregate, suggesting directed cell movement toward the aggregate. The pattern of cells at the base of taller, more mature aggregates suggested that groups of cells enter the aggregate from the surrounding band of cells by changing the pitch of their movement, thus creating an ascending spiral. Stalk formation was characterized by a distinctly different pattern, which suggested that single cells emerge from the band of cells and move toward the aggregate, under it, and then vertically to create the stalk. At this stage, the aggregate appeared to be torn from the substrate as it was lifted off the surface. The cells in the completed stalks were well separated, and most had their long axes pointed in a vertical direction. A great deal of the stalk material appeared to be slime in which the cells were embedded and through which they were presumably moving in the live material. Some suggestions regarding factors that may direct the observed morphogenetic movements are discussed.

Cell Division↗
PubMed1985

Lymphocyte function in human bone marrow. I. Characterization of two T cell populations regulating immunoglobulin secretion.

We analyzed the regulation of immunoglobulin (Ig) production in short-term cultures of human (rib) bone marrow cells. In contrast to blood or tonsil cell cultures, large quantities of IgG and IgA, but not IgM, were secreted by unstimulated marrow cells. The addition of pokeweed mitogen or phytohemagglutinin resulted in the suppression of this Ig secretion. Both mitogens induced the production of high levels of interleukin 2 (IL 2) in marrow cultures, and the addition of IL 2 alone mimicked the suppressive effect of mitogens. Incubation of marrow cells with Epstein Barr virus resulted in enhanced Ig secretion, primarily of the IgM isotype. The addition of mitogen or IL 2 suppressed Ig production in these cultures as well. The mitogen-induced suppression of Ig secretion in stimulated or unstimulated marrow cultures was inhibited by the monoclonal anti-TAC (IL 2 receptor) antibody. Cell separation experiments indicated that the induction of suppressor activity in marrow cultures involved two distinct populations of marrow-resident T lineage cells. The first population responds to activation by mitogens with the production of IL 2. This population has a surface phenotype appropriate for helper T cells. The second T cell population expresses T8 and TAC determinants. These cells acquire suppressor cell activity after exposure to IL 2. The expression of suppressor function does not require additional (e.g., mitogenic) activation signals. The IL 2-dependent marrow suppressor T cells represent a newly recognized T lymphocyte subset. The regulatory pathway delineated may be important for the regulation of antibody formation in bone marrow, the major site of Ig production in man.

Bone Marrow↗
PubMed1985

Reconstitution of nude mouse T cell function in vivo: IL 2-independent effect of human T cells.

The i.p. injection of 1 to 5 X 10(6) heavily irradiated human T lymphocytes resulted in the lasting reconstitution of T cell functions in young mice bearing the nu/nu mutation. IgM and IgG responses to immunization with sheep red cells or ovalbumin, splenic lectin responses, and the expression of easily detectable Thy-1 determinants on up to 20% of spleen cells could be documented for several months after the injection of human cells. Only a narrow cell dose range was effective. Injection of larger cell numbers not only failed to induce immune reconstitution but also resulted in the development of resistance to subsequent treatments. Only mature T cells, but not thymocytes, could induce nude mouse T cell development. Lymphoblasts from one patient with acute T cell leukemia consistently immune-reconstituted nude recipients. These cells were completely unable to produce IL 2 in vitro. In contrast, the IL 2-producing T cell line Jurkat was ineffective, indicating that the abilities to produce IL 2 and to induce nude mouse T cell development are independent. In an extension of earlier models of the nude mouse immune defect, two distinct T precursor cell pools are proposed as the major components of an extrathymic differentiation pathway. As an adequate trigger of differentiation, interaction with thymus-processed T cells guides the development of precursors in the first cell pool towards populating the second IL 2-responsive pool of T precursor cells.

Animals↗
PubMed1985

Recurrent thrombotic thrombocytopenic purpura in early pregnancy: effect of uterine evacuation.

A 29-year-old woman developed thrombotic thrombocytopenic purpura on two occasions, each with onset at about the 13th week of gestation. Despite therapy during each episode with corticosteroids, platelet aggregation-modifying agents and repeated plasmapheresis, she experienced only transient improvement. In both instances, however, prompt hematologic recovery followed evacuation of the uterus. During an 18-month interval between pregnancies, her blood count remained normal and she continues in remission. The authors suggest that when thrombotic thrombocytopenic purpura appears in early pregnancy and its response to conventional management is minimal, immediate evacuation of the uterus may be an effective therapeutic alternative.

Abortion, Induced↗
PubMed1984

Glucose intolerance in sarcoma patients.

Twenty-seven otherwise healthy patients with localized sarcoma were examined to determine if glucose intolerance can be detected before the appearance of clinical signs of cachexia. No patient had lost weight or demonstrated severe malnutrition. Fasting plasma samples for glucose, insulin, glucagon, and free fatty acids (FFA) were obtained, and a standard intravenous glucose tolerance test performed. Glucose disappearance rate (K) was calculated between 5 and 60 minutes. K levels were compared to those of normal controls and to those of patients with more extensive cancer (statistics obtained from the literature). Levels for K were compared to tumor volume measurements following surgery. Fasting glucose, insulin, and glucagon levels were normal. Fasting FFA levels were slightly elevated. K levels for sarcoma patients were significantly lower than in control patients (P = 0.04), and higher than in patients with advanced cancer (P less than 0.0001). The subset of patients who weighed less than the ideal had a significantly lower K level than did the rest of the sarcoma population. K levels correlated inversely with tumor volume (r = -0.34; P = 0.04). These data indicate that mild glucose intolerance (reduction in clearance of a glucose load) occurs early in untreated sarcoma patients, is most prevalent in patients who maintain less than the ideal weight, correlates with tumor burden, and occurs before other signs of cachexia appear.

Adolescent↗