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Biomedical subjects

P Conrad

Publications and source records attributed to P Conrad.

At least 19 recordsLinked to original sources
PubMed1992

Mechanism of peripheral T cell activation by coengagement of CD44 and CD2.

A number of CD44 antibodies are known to augment peripheral T cell proliferation stimulated with suboptimal concentrations of activating pairs of CD2 mAb. These findings have implicated the CD44 adhesion receptor in the activation of peripheral T cells via CD2. We have investigated early events after CD44 and CD2 coengagement on peripheral T cells. CD44 and CD2 coengagement resulted in enhanced [Ca2+]i mobilization. However, the increase in [Ca2+]i mobilization did not occur until at least 3 min after CD2 and CD44 coengagement, suggesting that other events precede the elevation in [Ca2+]i. Using a T cell/fibroblast adhesion assay, we could demonstrate a dramatic increase in T cell adhesiveness after about 1 min after CD44 and CD2 coengagement. The increase in T cell adhesiveness was comparable to that induced by PMA. In the absence of antibodies or treatment with mAb directed to other T cell surface Ag, there was little if any adhesion between unstimulated peripheral T cells and fibroblasts. Enhancement of T cell adhesiveness through CD44 engagement was not mediated by a direct effect on lymphocyte-function associated Ag-3, the known ligand of CD2. However, cross-linking of CD44 resulted in epitopic modulation of CD2 as demonstrated by the increased expression of the T11(3) activation epitope. Furthermore, anti-CD44 could substitute for anti-T11(2) in the activation of peripheral T cells via CD2. These results suggest that CD44 ligation has profound effects on CD2-mediated events by inducing epitopic modulation of CD2.

Antigens, CD↗
PubMed1992

The new corporate health ethic: lifestyle and the social control of work.

A corporate health ethic, forged in U.S. industry in the 20th century, clearly demarcated boundaries between private and workplace health concerns. This article advances evidence that the boundary is blurring, and argues that trends in workplace initiatives, including employee assistance, wellness programs, and drug screening, are giving shape to a new corporate health ethic. The new ethic emphasizes workers' lifestyles on and off the job, engendering a shift in corporate jurisdiction over employee health and behavior. Economic arguments such as "health care cost containment" are commonly offered as explanations for these new health initiatives. But the authors see the new ethic as a deeper response to a changing corporate environment and, more fundamentally, as emblematic of changes in the social control of work and productivity. They argue that the new health ethic may be a harbinger of new forms of social control in the workplace.

Health Behavior↗
PubMed1991

Hemolytic anemia caused by Babesia gibsoni infection in dogs.

Babesia gibsoni caused severe hemolytic anemia in 11 dogs from southern California. The most common clinical signs of B gibsoni infection were lethargy, anorexia, anemia, and thrombocytopenia. Acute infection with B gibsoni may be misdiagnosed as autoimmune hemolytic anemia. Diagnosis was most reliably determined by identification of the intraerythrocytic parasites on Giemsa-stained blood smears. The pathogenicity of B gibsoni, difficulties in diagnosis, the parasite's resistance to treatment with available drugs, and frequent interstate movement of dogs indicate that this disease may be a serious threat to dogs throughout the United States.

Anemia, Hemolytic↗
PubMed1991

Human interleukin-7 induces proliferation of neoplastic cells from chronic lymphocytic leukemia and acute leukemias.

The biologic effects of interleukin-7 (IL-7) and the expression of specific IL-7 membrane receptors on isolated neoplastic cells from previously untreated patients with chronic lymphocytic leukemia as well as acute leukemias were investigated in vitro. Leukemic cells were incubated for up to 6 days with various concentrations of IL-7 (0.01 to 2,000 U/mL). Neoplastic cells of the T- or B-phenotype from chronic as well as from acute leukemias proliferated in a dose-dependent manner. Cells from acute myeloid leukemias also proliferated in response to IL-7. An optimal proliferative effect was achieved between 96 and 120 hours with 200 U/mL IL-7. Combinations of IL-7 with IL-2 and tumor necrosis factor-alpha showed an additive effect on [3H]TdR incorporation. IL-7 binding assays gave a value of approximately 33 to 180 high-affinity (kd approximately 20 pmol/L) binding sites/cell and approximately 241 to 3,280 low-affinity (kd approximately 600 pmol/L) binding sites/cell. Receptor expression correlated with the proliferation in response to IL-7. These data indicate that IL-7 can induce proliferation of relatively mature tumor cells, and that this effect is not restricted to the lymphoid lineage.

Adult↗
PubMed1991

Enhancement of CD2-mediated T cell activation by the interaction of VLA-4 with fibronectin.

Human fibroblasts were shown to enhance the proliferation of peripheral T cells in the presence of suboptimal concentrations of anti-CD2 antibodies (anti-T112 and anti-T113) and agonistic anti-VLA-4 antibody. Evidence is provided that the interaction of VLA-4 with immobilized fibronectin can enhance the proliferation of T cells subjected to suboptimal stimulation via CD2. Our results suggest that the fibroblast-stimulated T cell proliferative response to low doses of anti-T112 and T113 antibodies is due to the interaction of VLA-4 with fibroblast fibronectin. These findings also suggest a role for the fibronectin/VLA-4 interaction in the inflammatory process.

Antibodies, Monoclonal↗
PubMed1990

Neutral-sugar transport by rat liver lysosomes.

Transport of D-glucose was studied in Percoll-gradient-purified rat liver lysosomes. D-Glucose uptake had a Km of 22 mM and a t1/2 of approx. 30 s. D-Fucose, 2-deoxyglucose and methyl alpha-glucoside were the most effective competitors for uptake of D-glucose, although D-galactose, D-mannose, D-xylose and L-fucose also appeared to compete for uptake. L-Glucose was a poor competitor for uptake. No competition was observed with N-acetyl-D-glucosamine, N-acetyl-D-galactosamine, D-glucuronic acid, N-acetylneuraminic acid, D-glucosamine or the amino acids L-glycine, L-lysine and L-proline. Uptake was unaffected by N-ethylmaleimide, dithiothreitol, KCl, NaCl, ATP/Mg or alteration of buffer pH. D-Glucose efflux from lysosomes was temperature-dependent, with a Q10 of 2.3, and was inhibited by cytochalasin B. Counter-transport could not be demonstrated. In contrast, L-fucose uptake had a Km of 65 mM and was largely unaffected by 5 M excess of neutral D-sugars. Both uptake and efflux of L-fucose were inhibited by cytochalasin B. It appears that lysosomes possess a facilitated transport system for D-glucose and perhaps other neutral D-sugars that is discrete from transport systems for acetylated and acidic sugars.

Animals↗
PubMed1988

Health and fitness at work: a participants' perspective.

In the 1980s worksite health promotion or wellness programs have become more common in American corporations. Corporations see them as a way to control rising health care costs and to improve employee health. This paper examines participants' perspectives on participation in a health and fitness program, based on participant-observation and 35 in-depth interviews with members of one corporate program. Participants have a decided fitness-orientation (as opposed to a health-orientation), focusing on staying in shape and controlling weight. The consequences of this orientation for the promotion of health, the future of wellness programs, and the corporation are discussed.

Adult↗
PubMed1986

German pelviscopic statistics for the years 1978-1982.

The second set of statistics on pelviscopy in Germany included information on 269,603 pelviscopies done in 322 general hospitals, and 22,859 pelviscopies done in private clinics between 1978 and 1982. In general hospitals the rate of serious complications was 1.9% and in private clinics 2.0%. Injuries to large blood vessels headed the list of complications. The main technique for tubal sterilization was the bipolar high-frequency current method with 75% in general hospitals and 73.1% in private clinics, followed by the endocoagulation technique according to Semm (36.8%). Sterilization failures were reported in 2.6%. Most failures were reported after sterilization with the bipolar electrocoagulation technique, followed by the clip technique. The rate of post-sterilization ectopic pregnancies was 1.06%. The highest rate of ectopic pregnancies was reported after using the bipolar tubal sterilization method (1.4%).

Blood Vessels↗
PubMed1979

Insulin binding to monocytes in trained athletes: changes in the resting state and after exercise.

Insulin binding to monocytes was examined in trained athletes (long distance runners) and in sedentary control subjects in the resting state and after 3 h of exercise at 40% of maximal aerobic power. At rest, specific binding of 125-I-insulin to monocytes was 69% higher in athletes than in sedentary controls and correlated with maximal aerobic power. The increase in insulin binding was primarily due to an increase in binding capacity. During acute exercise, insulin binding fell by 31% in athletes but rose by 35% in controls. The athletes had a smaller decline in plasma glucose and a lower respiratory exchange ratio during exercise than did controls. We conclude that physical training increases insulin binding to monocytes in the resting state but results in a fall in insulin binding during acute exercise. Changes in insulin binding in athletes thus may account for augmented insulin sensitivity at rest as well as a greater shift from carbohydrate to fat usage during exercise than is observed in untrained controls.

Adult↗
PubMed1977

Situational hyperactivity: a social system approach.

A sociological approach for viewing hyperactivity has been proposed. Its explanatory power may at this time be limited to differentiating between situational hyperactivity and a medical model for explaining the syndrome. Further research could serve to expand and illuminate this theory. However, even as presently formulated, by focusing on situational hyperactivity we have a perspective that returns meaning to the child's behavior. We can now inquire as to what hyperactive children can tell us about school systems, family structure, and the position of children in our own society. Putting meaning back into explanations of behavior can produce greater insights into our understanding of children and the social systems in which they operate.

Child↗
PubMed1975

Sclerostripping--a "new" procedure for the treatment of varicose veins.

A "new" procedure for dealing with varicose veins associated with severe-to-moderate long saphenous vein incompetence is described. It consists of a combination of high ligation of the saphenofemoral junction and stripping of the long saphenous vein, with compression sclerotherapy of its tributaries and veins which are varicose because of incompetent perforators at the time of the operation. A series of 150 patients treated over a period of four years by this method is described. The safety, effectiveness, and advantages of the method over those of more orthodox surgery are discussed. It is suggested that it is safe, and more effective than more orthodox operations.

Bandages↗