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Biomedical subjects

W C Yang

Publications and source records attributed to W C Yang.

At least 109 records · Page 6Linked to original sources
PubMed1991

Cellular immune responses in pigs fed a vitamin E- and selenium-deficient diet.

The effects of dietary restriction of vitamin E (Vit E) and selenium (Se) on lymphocyte proliferation, natural killer (NK) cell activity, antibody-dependent cell-mediated cytotoxicity (ADCC), and on burst respiratory response of stimulated granulocytes as measured by chemiluminescence (CL) were studied in pigs. Six male weanling pigs were maintained for 25 d on a torula yeast-based diet containing no measurable amount of alpha-tocopherol and less than .02 mg of Se per kilogram of feed. Six others received the same basal diet supplemented with 33 IU of DL-alpha-tocopheryl acetate and .2 mg of Se per kilogram of feed. All pigs were inoculated with Salmonella typhisuis on d 21 of the feeding period and killed on d 25. Tests to measure cellular immune functions were performed on cells isolated from blood samples taken on d 21 and 25. After 21 d of feeding, lymphocyte blastogenesis responses to phytohemagglutinin, concanavalin A, and pokeweed mitogen in pigs fed the Vit E- and Se-deficient diet were normal compared with the response in pigs fed the supplemented diet. Moreover, the cytotoxic activity of NK cells, the ADCC response, and the CL response of granulocytes were not affected. After 25 d, a marked suppression of lymphocyte response to mitogens occurred in pigs fed the Vit E- and Se-deficient diet when the cells were cultured in the presence of autologous serum. When fetal bovine serum replaced autologous serum in the cultures, no suppression was observed. No effect on NK activity and ADCC was observed, whereas the CL peak response of granulocytes tended to be higher in pigs fed the deficient diet.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Chlorobutanol, a preservative of desmopressin, inhibits human platelet aggregation and release in vitro.

Therapeutic preparations of desmopressin for parenteral use contain the preservative chlorobutanol (5 mg/ml). We show here that chlorobutanol is a potent inhibitor of platelet aggregation and release. It exhibited a significant inhibitory activity toward several aggregation inducers in a concentration- and time-dependent manner. Thromboxane B2 formation, ATP release, and elevation of cytosolic free calcium caused by collagen, ADP, epinephrine, arachidonic acid and thrombin respectively were markedly inhibited by chlorobutanol. Chlorobutanol had no effect on elastase-treated platelets and its antiplatelet effect could be reversed. It is concluded that the antiplatelet effect of chlorobutanol is mainly due to its inhibition on the arachidonic acid pathway but it is unlikely to have a nonspecific toxic effect. This antiplatelet effect of chlorobutanol suggests that desmopressin, when administered for improving hemostasis, should not contain chlorobutanol as a preservative.

Adenosine Triphosphate↗
PubMed1990

Immune responses to Herpesvirus sylvilagus infection in cottontail rabbits.

Immunologic changes produced by Herpesvirus sylvilagus infection of cottontail rabbits were investigated to evaluate this virus infection system as an animal model for EBV infection in humans. H. sylvilagus neutralizing antibodies appeared as early as 7 days after infection, peaked 2 to 4 wk postinfection and decreased to low levels by 8 to 10 wk postinfection. Complement-dependent antibodies mediating the protection of in vitro infection of monocytes and Con A-stimulated lymphoblasts with H. sylvilagus were observed as were complement-dependent cytotoxic antibodies against H. sylvilagus-infected cells. No cytolytic activity was present in sera taken either before or 3 days after infection; cytolysis was first observed 7 days after infection. The development of cytolytic antibodies appeared to be biphasic during an infection course of 12 to 16 wk. In vivo induction of a primary cytotoxic lymphocyte response to H. sylvilagus was also investigated. Splenic lymphocytes from infected animals lysed H. sylvilagus-infected skin fibroblasts; however, similar activity was not observed when PBMC or mesenteric lymph node lymphocytes were used as effector cells. H. sylvilagus-infected autologous skin fibroblasts were preferentially lysed as compared to heterologous skin fibroblasts. This virus-specific cytotoxic activity appeared 5 days postinfection and peaked 7 days postinfection. By 28 days postinfection, only low levels of cytotoxic activity were detected in spleen cells. Herpesvirus sylvilagus infection of cottontail rabbits provides an animal model for the study of lymphoproliferative disorders induced by herpesviruses.

Animals↗
PubMed1990

Analysis of voiding disorders in patients with cerebrovascular accidents.

Urodynamic evaluation was undertaken in 33 patients (15 males and 18 females, age range 48-90 years) with voiding problems following cerebrovascular accidents. In the majority of these patients (26) cystometry revealed involuntary contractions of the bladder. The critical volume for involuntary bladder contractions was approximately 200 mL. The majority of patients with cerebral cortex and/or internal capsule lesions had uninhibited relaxation of the sphincter during involuntary bladder contractions, while all of the patients with lesions only in the basal ganglia or thalamus had normal sphincter function. The remaining 7 patients had poor bladder contractions. Correlation of bladder dysfunction with the area of brain injury was not conclusive, but was suggestive of directions to be taken in future research.

Aged↗
PubMed1990

OKT3 induction via idiotypic networks of mirror-image immunosuppressive antiimmunoglobulins in renal transplant recipients.

Four of 21 renal transplant recipients treated with OKT3 for rejection episodes developed a second sustained (approximately 2 weeks) depression in CD3 peripheral blood lymphocyte cell-surface-marker expression. This occurred after OKT3 therapy had ceased, subsequent to a return toward baseline CD3 levels seen before OKT3 therapy was instituted. The second decrease in CD3 T cell counts was dissociated from CD2 marker T cell counts using flow cytometry and coincided with transient cytomegaloviral infections. Three phases of immunosuppression were defined in these 4 patients: phase I (during OKT3 treatment); phase II (after treatment when CD3 counts were reconstituted); and phase III (when CD3 counts again were depressed). During phase III, serum of the 4 affected patients could transfer a blocking effect on the expression of the CD3 marker of peripheral blood T cells of "normal" laboratory volunteers. Contained in these sera were human IgG antibodies that bound on Western blot analysis and by radioautography after immunoprecipitation to a protein band of a T cell membrane lysate with an m.w. of 23 kD. The reaction was identical to that seen with OKT3 (immunoprecipitation). Moreover, this Western blot binding could be virtually (but not completely) eliminated by multiple absorptions of the T cell membrane lysate with OKT3. By using an affinity-purified human anti-OKT3 IgG from one of the 4 patients, it was possible to immunoabsorb from phase III sera the CD3 blocking activity as well as the binding to the 23 KD protein band. A reverse immune absorption by the phase III sera with the anti-OKT3 IgG after ultracentrifugation prevented the anti-OKT3 IgG from binding to OKT3 coated plates in solid-phase radioimmunoassay. These data support the notion that autoimmune human anti-anti-id (Ab2) antibodies can occasionally be generated by treatment with OKT3, which are directed against CD3 complex epitopes similar to the ligand of OKT3.

Adolescent↗
PubMed1990

Reduction of serum calcium by sodium sulfonated polystyrene resin.

Sodium resin has been clinically administered against hyperkalemia widely, but its effects of lowering the serum calcium has never been documented. In our study, 7 patients with chronic renal failure were chosen at random to take sodium resin 30 g per day for 3 days. The sodium resin not only lowered the serum potassium level (p less than 0.05) but also brought down the level of serum calcium (p less than 0.05). The reduced ability of patients with chronic renal failure to absorb calcium from the gastrointestinal tract is well recognized, so its effects of lowering calcium will be more likely to aggravate the serum calcium imbalance further. If sodium resin has to be used for the maintainance of serum potassium in patients with chronic renal failure the serum calcium should be monitored closely in order to lighten the osteodystrophy and secondary hyperparathyroidism.

Adult↗
PubMed1989

Effects of vaccines on the canine immune system.

The effects of several commercially available polyvalent canine vaccines on the immune system of the dog were examined. The results demonstrated that the polyvalent vaccines used in this study significantly suppressed the absolute lymphocyte count and that most of the polyvalent vaccines significantly suppressed lymphocyte response to mitogen, but had no effect on natural effector cell activity, neutrophil chemiluminescence, nor antibody response to canine distemper virus. The individual vaccine components from the polyvalent vaccines when inoculated alone did not significantly suppress the lymphocyte response to mitogen. However, when canine distemper virus was combined with canine adenovirus type 1 or canine adenovirus type 2, significant suppression in lymphocyte responsiveness to mitogen occurred. The results indicate that interactions between canine distemper virus and canine adenovirus type 1 or canine adenovirus type 2 are responsible for the polyvalent vaccine induced suppression of lymphocyte responsiveness.

Adenoviridae↗
PubMed1988

Interactions of chloride and amiloride with the renal Na+/H/ antiporter.

Amiloride is a reversible inhibitor of the Na+/H+ antiporter which acts at the external aspect of the transport system. The kinetics of inhibition of the Na+/H+ antiporter with amiloride have been controversial, with the usual finding of simple competitive inhibition, but with other reports of mixed and noncompetitive inhibition of the transporter by amiloride. The present experiments demonstrate that the chloride content of the external transport buffer affects the kinetics of amiloride inhibition. Either simple competitive or mixed inhibition by amiloride was observed in the same vesicle preparations depending on the presence of chloride or gluconate in the buffer. The effect of chloride on the inhibitory effect of amiloride was dependent on the concentration of chloride and amiloride. Similar effects were observed with more potent analogues of amiloride. These findings suggest that the external aspect of the antiporter has a site or sites at which the inhibitory effects of amiloride on the Na+/H+ antiporter can be modified by chloride, even though chloride has only slight effects on the kinetics of the Na+/H+ antiporter in the absence of amiloride.

Amiloride↗
PubMed1988

Ontogeny of mitogen responsive lymphocytes in the bovine fetus.

Bovine fetal lymphocytes were examined for their ability to respond to the mitogens phytohemagglutinin (PHA), Concanavalin A (ConA) and pokeweed mitogen (PWM) in the lymphocyte blastogenesis test (LBT). PHA-, Con A- and PWM-responsive lymphocytes appeared simultaneously at 75-80 days of gestation. The response increased with age of the fetus until, by 120 days of gestation, the response to PHA, Con A and PWM of many fetuses was in the range of values obtained with lymphocytes from normal adult cattle.

Animals↗
PubMed1988

Epidemiologic and immunologic evaluation of an outbreak of canine blastomycosis.

Five confirmed cases of canine blastomycosis occurred over the 10-month period of December 1983 to September 1984 in a south-eastern Wisconsin colony of 30 dogs maintained for sled competition. Contrary to other published reports of canine blastomycosis, the sex-specific attack rates were higher among females than males. Four of the five confirmed cases and all four deaths occurred among young female dogs. Differences in the age distribution and/or the micro-environment of the females may have contributed at least in part to the difference in sex-specific attack rates. The serologic response and leukocyte function of the clinically affected and apparently healthy dogs from this colony were assessed during the outbreak. A survey of the adult dogs in the colony suggested that the mitogen-induced lymphocyte blastogenesis of dogs with clinical signs of blastomycosis was suppressed compared with that of dogs that remained free of clinical signs. In contrast to previous reports that autologous sera from dogs and humans with clinical blastomycosis inhibited mitogen-induced lymphocyte blastogenesis, lymphocyte responsiveness was similar to, or greater in the presence of autologous canine serum than it was in the presence of fetal bovine serum.

Animals↗
PubMed1988

Pathogenesis of Herpesvirus sylvilagus infection in cottontail rabbits.

Experimental infection with Herpesvirus sylvilagus produces clinical and histopathologic changes in its natural host, the cottontail rabbit (Sylvilagus floridanus), similar to those observed in humans acutely infected with Epstein-Barr virus (EBV). Twenty-seven seronegative cottontail rabbits were infected with Herpesvirus sylvilagus and all developed antibodies within 10 days. Neutralizing antibody was detected as early as 7 days after infection. Virus was isolated from blood mononuclear cells, spleen, bone marrow, thymus, lymph nodes, kidneys, lung, and liver as early as 3 days after infection. Infected animals showed leucocytosis, monocytosis, and lymphocytosis with the appearance of atypical lymphocytes. Peripheral blood abnormalities peaked at 10-14 days after infection, and returned to normal by 28 days after infection, with the exception of atypical lymphocytosis that persisted in some animals for more than 2 years after experimental infection. More severe histopathologic changes were seen in virus-infected juvenile rabbits than adult rabbits; these changes included viral myocarditis, interstitial pneumonia, and lymphocytic myositis. Reactive hyperplasia and subsequent lymphocytic depletion of spleen and lymph nodes were reminiscent of that seen in virus-associated hemophagocytosis syndrome. Prominent lymphoid hyperplasia of many nonlymphoid organs, most notably the kidney and lungs, was observed. The development of these lymphoproliferative lesions and other lymphoid changes during H. sylvilagus infection suggest that this system may be a model to study similar lesions induced by EBV infection in humans.

Animals↗
PubMed1987

Anion exchanger is present in both luminal and basolateral renal membranes.

Binding of the anion-exchange inhibitor 3H2-labeled 4,4'-diisothiocyano-2,2'-stilbene disulfonic acid (DIDS) to highly purified luminal and basolateral beef kidney tubular membranes was characterized. Specific binding of [3H2]DIDS is present in both luminal and basolateral membranes. Scatchard analysis revealed a Kd for [3H2]DIDS of 5.5 microM and 19.3 microM and a maximal number of binding sites of 10.9 nmol and 31.7 nmol DIDS/mg protein in basolateral and luminal membranes, respectively. To assess the role of this putative anion exchanger on transport we measured 35SO4 uptake by luminal and basolateral membranes. In both luminal and basolateral membranes sulfate uptake was significantly greater in the presence of an outward-directed Cl gradient, OH gradient or HCO3 gradient than in the absence of these gradients. There was an early anion-dependent sulfate uptake of five to ten times the equilibrium uptake at 60 min. The sulfate taken in could be released by lysis of the vesicles indicating true uptake and not binding of sulfate. No significant difference in SO4 uptake was found in the presence and in the absence of valinomycin, indicating that the anion exchanger is electroneutral. The anion-dependent sulfate uptake was completely inhibited by either DIDS or furosemide in both luminal and basolateral membranes. Dixon analysis of HCO3-dependent SO4 uptake by luminal membranes in the presence of different concentrations of DIDS revealed a Ki for DIDS of 20 microM. The similar values of the Kd for [3H2]DIDS binding and the Ki for DIDS inhibition of SO4 uptake might suggest an association between DIDS binding and the inhibition of SO4 transport. In addition, an inward-directed Na gradient stimulated sulfate uptake in luminal but not in basolateral membranes. The Na-dependent sulfate uptake in luminal membranes was also inhibited by DIDS. We conclude that, in addition to the well-known Na-dependent sulfate uptake in luminal membranes, there exists an anion exchanger in both basolateral and luminal membranes capable of sulfate transport.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1987

Bilateral symptomatic intraspinal T12-L1 synovial cysts.

A 72-year-old man presented with several months of increasing lumbar pain, sciatica, lower extremity weakness, numbness in his buttocks and posterior thighs, burning sensations in his scrotum, and urinary incontinence. Myelogram-computed tomography scan demonstrated a high grade incomplete block at the T12-L1 level due to bilateral synovial cysts and simultaneously a high grade partial block at L4-L5 due to spinal stenosis. Laminectomy of the T-12 vertebra and partial laminectomy of the L-1 vertebra with excision of both synovial cysts and laminectomies of the L-4 and L-5 vertebrae with foraminotomies resulted in a reversal of the patient's symptomatology.

Aged↗
PubMed1987

Isolation and characterization of porcine natural killer (NK) cells.

The morphologic and biological properties of porcine cells mediating natural killer (NK) activity were determined. In a previous study, we demonstrated that lymphocytes from the peripheral blood of pigs greater than 1 week of age possessed NK activity to K562 tumor cells and that lymphocytes from the blood and spleen of pigs greater than 1 day of age were able to mediate natural cytotoxicity against parainfluenza-3 (PI3) virus-infected Vero cells (Yang and Schultz, 1986a). Discontinuous density gradients were used to enrich NK cells. NK cytotoxicity was mainly present in high-density Percoll fractions (50 to 55% and 55 to 60%); little or no NK activity was present in lower density fractions. The NK cell enriched lymphocytes responded to the mitogens PHA, ConA and PWM. NK cells were sensitive to the suppressive effect of corticosteroid, but Protein A did not affect NK activity. The amount of cytotoxicity directly corresponded to the degree of binding that occurred between the NK enriched lymphocyte population and the target cells. Cytochemical and morphological studies demonstrated that these bond cells which are believed to be responsible for the NK activities, were mainly small to medium lymphocytes lacking azurophilic cytoplasmic granules. These findings were confirmed by ultrastructural studies of effector and "target-binding" cells. The results of the present study suggested that the cells mediating NK activity in pigs have the morphological and density characteristics of small and medium sized lymphocytes; findings that differ from those described for NK cells in human and other animal species.

Adrenal Cortex Hormones↗
PubMed1987

In vitro effects of prostaglandin E1, prostaglandin E2, indomethacin, histamine, and tuftsin on chemiluminescence response of bovine polymorphonuclear leukocytes.

The in vitro effects of prostaglandin E1 (PGE1), prostaglandin E2 (PGE2), indomethacin, histamine, and tuftsin on the chemiluminescence response of bovine polymorphonuclear cells (PMN) were determined. Addition of PGE1, PGE2, indomethacin, and histamine in vitro significantly suppressed the chemiluminescence response of bovine PMN's, whereas tuftsin had no effect. Suppression was dependent upon the continued presence of PGE1, PGE2, and histamine in the culture media. However, indomethacin's suppressive effect remained even after it was removed from the culture media. Hydrogen peroxide generated chemiluminescence was suppressed by high concentrations of indomethacin and histamine. Results of this study suggest possible pharmacologic or regulatory mechanisms for certain of these immune modulators in the control of the oxidative burst reaction of bovine PMN's.

Alprostadil↗
PubMed1987

The effects of glucocorticosteroids on the chemiluminescence response of bovine phagocytic cells.

The effects of corticosteroids on the chemiluminescence response of bovine phagocytic cells were determined both in vitro and in vivo. The in vitro addition of hydrocortisone or dexamethasone had no significant effect on the chemiluminescence response of leukocytes in a whole blood or purified polymorphonuclear leukocyte (PMN) population. Cattle that received a single 20 mg dose of dexamethasone or three 20 mg doses of dexamethasone (given 24 hours apart) demonstrated the expected effects on the bovine leukogram (leukocytosis, neutrophilia, lymphopenia, eosinopenia, and monocytosis) and also demonstrated the expected suppressive effect on lymphocyte response to phytohemagglutinin (PHA). However, neither a single nor multiple dexamethasone treatment(s) had an effect on the chemiluminescence response of phagocytes in whole blood, but significantly enhanced the chemiluminescence response of the purified PMN leukocyte population. There was no significant difference between the two dexamethasone treatment groups in either the degree or duration of the effects observed in the chemiluminescence or lymphocyte response assays.

Animals↗