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Biomedical subjects

D Smith

Publications and source records attributed to D Smith.

At least 1,099 records · Page 61Linked to original sources
PubMed1982

T cell chronic lymphocytic leukaemia with suppressor phenotype.

The peripheral blood cells from a patient with T cell chronic lymphocytic leukaemia were examined for surface marker and functional characteristics. Eighty-91% of the peripheral blood cells formed SRBC rosettes and 22-49% possessed Fc receptors; 73% of the peripheral blood cells were reactive with the OKT8 antiserum and 61% expressed DR antigens. Response to PHA stimulation was markedly reduced, whereas allogeneic responsiveness in mixed leucocyte culture was intact. The ability of Con A-stimulated peripheral blood cells to generate suppressor activity in a mixed leucocyte reaction was deficient, whereas suppression of in vitro immunoglobulin synthesis was greater than normal. The leukaemic peripheral blood cell population expressed a T suppressor phenotype. Functional studies suggest that these cells were derived from the subset of T lymphocytes with regulatory activity for immunoglobulin synthesis as opposed to mitogenic responsiveness.

Adult↗
PubMed1981

Possible relationship between in utero diethylstilbestrol exposure and male fertility.

Seventeen men who were exposed in utero to diethylstilbestrol (DES), 12 non-DES-exposed volunteers, and 11 fertile control subjects were evaluated by physical examination, seminal fluid analysis, and sperm penetration assay (SPA). Fourteen of the 17 male subjects exposed to DES in utero and two of the 12 non-DES-exposed volunteers had SPAs of less than 14% and qualified as infertile by the criteria of this test. All 11 fertile control subjects had demonstrated SPA values in the fertile range. Thirteen of the 17 DES-exposed male subjects, four of the 12 non-DES-exposed volunteers, and four of the 11 fertile control subjects demonstrated at least one abnormality of the reproductive organs.

Adolescent↗
PubMed1981

Epstein-Barr viral DNA: infectivity for human placental cells.

Purified DNA of Epstein-Barr virus (EBV) is regularly infectious by means of the "calcium" method of transfection. Cultured human placental cells exposed to EBV DNA of two transforming strains, FF41 and B95, produce virus that is capable of converting normal B lymphocytes into established cell lines. After treatment with EBV (FF41) DNA and EBV (HR-1) DNA the placental cells display antigens associated with the productive viral cycle. The placental cells have not developed foci or other signs of morphologic transformation.

Antigens, Viral↗
PubMed1981

Plasmacytic differentiation of circulating Epstein-Barr virus-infected B lymphocytes during acute infectious mononucleosis.

During the acute phase (1 wk of symptoms or less) of infectious mononucleosis (IM), 70--80% of circulating Epstein-Barr virus nuclear antigen (EBNA)-positive cells have differentiated toward plasma cells. Thus the characteristics of the infected cells in the majority of IM patients during early disease are indistinguishable from EBNA-positive tumor cells of a previously reported child who developed lymphoma during IM. IgA and IgG were the most frequent and IgM the least frequent immunoglobulin isotypes detected in EBNA-positive cells. In acute disease EBNA was present in 5.5--20% of T cell-depleted blood lymphocytes but in the 2nd or 3rd wk of illness the number of EBNA-positive cells sharply decreased to 0.4--1.4%. At the same time the fraction of antigen-positive cells containing cytoplasmic immunoglobulins also diminished, suggesting either that differentiation of infected cells was altered during the disease or that nondifferentiated antigen-positive cells had a survival advantage. Both the high proportion of plasmacytic EBNA-positive cells seen during acute disease and the apparent loss of differentiation by these cells later in disease may be regulated by host immunologic factors. Immunoglobulin-producing EBNA-positive cells may be the source of heterophile antibodies and other seemingly inappropriate antibodies usually found in serum during IM; however, increased numbers of noninfected plasma cells were present in some patients and may also be a potential source of these unusual antibodies.

Acute Disease↗
PubMed1981

Altered cellular immune functions in patients with Down's syndrome.

Cell-associated immunocompetence was evaluated in 42 patients with Down's syndrome (DS) and compared with that of institutionalized patient control and normal control groups. B lymphocytes, as both percent of total lymphoid cells and absolute number, were markedly reduced in patients with DS. T-lymphocyte proliferative response to phytohemagglutinin mitogen also was significantly decreased. This altered response of the lymphocyte population was evident in both the presence and absence of accessory helper monocytes. Increased Fc receptor (FcR) cell activity, as measured by antibody-dependent cellular cytotoxicity was seen in both the patients with DS and the control patients. This probably resulted from common environmental factors such as exposure to infectious factors such as exposure to infectious agents. No change was found in the WBC counts, percentages of lymphocytes and monocytes, percentages of t cells and FcR cells, or in the natural killer cell activity.

Adult↗
PubMed1981

A high voltage electrometer for recording and iontophoresis with fine-tipped, high resistance microelectrodes.

A high voltage electrometer is described which incorporates a controlled current source, direct current monitoring, balance bridge, electrode resistance, and capacitance compensation test circuits. This device is suitable for making biophysical measurements and iontophoresing dyes or enzymes through extremely fine micropipettes with impedances an order of magnitude higher than conventional micropipettes. Such electrodes are useful for recording from the small neurons of the central nervous system in vivo.

Animals↗
PubMed1981

Alternative solutions to kinetic stimulus transformations.

It has been assumed that certain stimulus transformations lead directly to depth effects, that is, that such transformations are the necessary and sufficient conditions for kinetically generated depth perception. An alternative is to view such perception as the preferred solution to the problem posed by the transforming stimulus as to what even in the world is producing that transformation. In several experiments it is shown that when other solutions are supportable by the stimulus, those same transformations will no longer lead to depth perception. These other solutions become preferred on the basis of rejection of certain coincidental features of the stimulus that otherwise would have to be accepted were the kinetic depth solution to be maintained. The findings are interpreted as challenging any theory that perception is simply the direct result of stimulation or of extraction of stimulus information and as supporting the Helmkoltzian rule of perception as a construction of the most reasonable representation.

Depth Perception↗
PubMed1981

Traumatic left ventricular aneurysm in an 8-year-old child.

An asymptomatic 8-year-old boy was found to have a left ventricular aneurysm and a ventricular septal defect 14 months after a road traffic accident. At operation a large, thin-walled, clot-filled aneurysm was removed and the septal defect repaired.

Child↗
PubMed1981

Insulin resistance in uremia.

Tissue sensitivity to insulin was examined with the euglycemic insulin clamp technique in 17 chronically uremic and 36 control subjects. The plasma insulin concentration was raised by approximately 100 microU/ml and the plasma glucose concentration was maintained at the basal level with a variable glucose infusion. Under these steady-state conditions of euglycemia, the glucose infusion rate is a measure of the amount of glucose taken up by the entire body. In uremic subjects insulin-mediated glucose metabolism was reduced by 47% compared with controls (3.71 +/- 0.20 vs. 7.38 +/- 0.26 mg/kg . min; P less than 0.001). Basal hepatic glucose production (measured with [3H]-3-glucose) was normal in uremic subjects (2.17 +/- 0.04 mg/kg . min) and suppressed normally by 94 +/- 2% following insulin administration. In six uremic and six control subjects, net splanchnic glucose balance was also measured directly by the hepatic venous catheterization technique. In the postabsorptive state splanchnic glucose production was similar in uremics (1.57 +/- 0.03 mg/kg . min) and controls (1.79 +/- 0.20 mg/kg . min). After 90 min of sustained hyperinsulinemia, splanchnic glucose balance reverted to a net uptake which was similar in uremics (0.42 +/- 0.11 mg/kg . min) and controls (0.53 +/- 0.12 mg/kg . min). In contrast, glucose uptake by the leg was reduced by 60% in the uremic group (21 +/- 1 vs. 52 +/- 8 mumol/min . kg of leg wt; P less than 0.005) and this decrease closely paralleled the decrease in total glucose metabolism by the entire body. These results indicate that: (a) suppression of hepatic glucose production by physiologic hyperinsulinemia is not impaired by uremia, (b) insulin-mediated glucose uptake by the liver is normal in uremic subjects, and (c) tissue insensitivity to insulin is the primary cause of insulin resistance in uremia.

Adult↗
PubMed1981

Immunocytochemical localization of fibronectin in limb tissues of the adult newt, Notophthalmus viridescens.

This study describes the immunocytochemical localization of fibronectin, a defined connective tissue and plasma glycoprotein, and its relationship to collagen and reticulin in adult newt limb tissues. We have also isolated the plasma form of fibronectin in a related species, the adult mudpuppy. The insoluble form of fibronectin was detected with immunoperoxidase stain in basement membranes and loose connective tissue. The endoneurium and perineurium of nerve bundles and the connective tissue elements of striated muscle stained heavily for fibronectin. The dermis and blood vessel walls also reached positively with the immunoperoxidase stain. A similar distribution was observed for reticulin with conventional histologic techniques with the exception of the dermis where only trace amounts of the protein were observed. Fibronectin and collagen were codistributed in the tissues studies. Fibronectin appeared to be intercalated among larger collagenous fibers. Collagen and fibronectin form an extracellular connective tissue scaffold that abuts against many types of adherent cells in different tissues. This supports the possible role of fibronectin in cell-matrix interactions and normal cell and tissue organization.

Animals↗