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Biomedical subjects

W C Yang

Publications and source records attributed to W C Yang.

At least 127 records · Page 7Linked to original sources
PubMed1987

Inhibition of bovine lymphocyte response to phytohemagglutinin by a specific 5-lipoxygenase inhibitor.

AA861, a specific 5-lipoxygenase inhibitor, inhibited bovine lymphocyte response to phytohemagglutinin (PHA). Mitogen-stimulated cultures of mononuclear cells produced leukotriene B4 (LTB4) in 24 hours. The production of LTB4 was completely inhibited by concentrations of AA861 that inhibited mitogen-induced 3H-thymidine incorporation. The inhibition of lymphocyte proliferation was totally reversed by LTB4 but not by leukotriene C4 or leukotriene D4. The inhibition of interleukin-2 (IL-2) production by AA861 was also completely reversed by addition of exogenous LTB4 to lymphocyte cultures. Thus, endogenous LTB4 production appeared to be necessary for PHA-induced IL-2 production and lymphocyte proliferation.

Animals↗
PubMed1987

Chronic hypercapnia enhances Vmax of Na-H antiporter of renal brush-border membranes.

Chronic hypercapnia is associated with increased proximal HCO3 reabsorption that is thought to be mediated by a Na-H antiporter. We hypothesized that chronic hypercapnia would be associated either with increased Vmax or with decreased Km of the Na-H antiporter. To test this hypothesis we made rabbits hypercapnic for 48 h by exposure to 10% CO2. In both control and hypercapnic animals, cortical luminal membranes were enriched over the homogenate 16-fold in alkaline phosphatase and 10-fold in maltase activity. The kinetic activity of the Na-H antiporter was measured by the dissipation of the quenching of acridine orange by addition of different Na concentrations. Chronic hypercapnic rabbits had significantly higher Vmax of the Na-H antiporter of luminal membranes than controls (593 +/- 81 vs. 252 +/- 40 arbitrary fluorescence units X min-1 X 300 micrograms protein-1, P less than 0.01). The Km, however, was not different between control and hypercapnic rabbits. 22Na uptake in presence of an outwardly directed pH gradient was significantly higher in vesicles from hypercapnic rabbits than controls. Amiloride inhibited the Na-H antiporter (as assessed by acridine orange quenching or 22Na uptake) to the same degree in membranes from both control and hypercapnic rabbits, suggesting that the increase in Vmax is mediated by the electroneutral component of the Na-H antiporter. In addition, under voltage clamp conditions by K and valinomycin the Vmax was still increased in membranes from hypercapnic animals, again suggesting that the increase in Vmax is mediated by the electroneutral component of the Na-H antiporter. The uptake of D-[3H]glucose by luminal membranes was not different between control and hypercapnic rabbits, indicating a specific enhancement of the Na-H antiporter. Acute hypercapnia (4 h) failed to increase the Vmax of the Na-H antiporter despite comparable increase in PCO2. Thus chronic hypercapnia, but not acute hypercapnia, induces a selective and specific increase in the Vmax of Na-H antiporter, and this may mediate the adaptation to chronic hypercapnia.(ABSTRACT TRUNCATED AT 250 WORDS)

Acidosis↗
PubMed1987

Na+-H+ antiporter in posthypercapnic state.

Posthypercapnic metabolic alkalosis has been attributed to decreased HCO3 excretion because of low glomerular filtration rate (GFR), volume contraction, or chloride depletion. We have previously shown that chronic hypercapnia enhances the Vmax of the Na+-H+ antiporter. We reasoned that an increased Vmax of the Na+-H+ antiporter could play a role in the maintenance of posthypercapnic metabolic alkalosis. To test this hypothesis, we measured the kinetics of the Na+-H+ antiporter by the dissipation of the quenching of acridine orange fluorescence in purified brush-border membrane obtained from posthypercapnic rabbits. The kinetic parameters were measured in controls and in rabbits that were exposed to hypercapnia for 48 h and then allowed to breathe room air for 3, 24, or 48 h. In luminal membranes prepared from posthypercapnic animals, the Vmax of the Na+-H+ antiporter was significantly increased after 3 and 24 h but not after 48 h compared with controls. The increase in Vmax was not different from that of hypercapnic animals. There was no difference in the Km of the Na+-H+ antiporter among these five groups. Amiloride inhibited the Vmax equally in membranes from control and posthypercapnic rabbits. Proton permeability was comparable among the groups. These data indicate that the increase in Vmax in posthypercapnic rabbits is mediated through the electroneutral Na+-H+ exchange and not through conductive H+ and Na+ pathway. Glucose uptake was not different in control and posthypercapnia, indicating a selective increase in Na+-H+ antiporter activity. At 3 and 24 h posthypercapnia, HCO3 concentration was higher than control.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorption↗
PubMed1987

Lateral pontine tegmental hemorrhage presenting as isolated trigeminal sensory neuropathy.

A 45-year-old man awoke with numbness and paresthesias on the right side of his face, scalp, ear, and tongue. CT and MRI demonstrated a focal hemorrhage in the dorsolateral right pontine tegmentum. Cerebral angiography was negative for vascular malformation or aneurysm. CT performed 1 month later showed complete resolution of the pontine hematoma, with residual minimal lateral pontine atrophy.

Brain Diseases↗
PubMed1987

Effect of parathyroid hormone fragments on calcium transport in toad bladder.

Parathyroid hormone (PTH) has a variety of biologic effects which are both dependent and independent on activation of adenylate cyclase. We studied the effects of intact PTH and PTH fragments on water flow and Ca transport in isolated toad bladder sacs. As reported previously by us, PTH (1-84) significantly stimulated basal water flow in isolated toad bladder sacs. Synthetic PTH 1-34, 44-68, 53-84 and 65-84 (1 microgram/ml) had no effect on basal water flow after a 60-min incubation period. Intact PTH (1-84) and synthetic 1-34 PTH significantly inhibited both arginine-vasopressin and cyclic AMP-stimulated water flow. Synthetic PTH 44-68, 53-84 and 65-84 (1 microgram m/ml) had no effect on arginine-vasopressin or cyclic AMP-stimulated water flow after a 60-min incubation. Intact PTH (1-84) and synthetic 1-34 PTH significantly stimulated 45Ca uptake without affecting 45Ca efflux. Synthetic PTH 44-68, 53-84 and 65-84 had no effect on either 45Ca uptake or 45Ca efflux. Although these results suggest that the intact hormone is required for the maximal effect of PTH on water flow, substantial activity resides in the amino terminal fragment of the hormone. No activity per se resides in the carboxy terminal portion of the hormone as regards water flow. Alterations in Ca transport appear to mediate the effect of PTH on water flow. These effects are independent of activation of adenylate cyclase because these hormones also inhibit cyclic AMP-stimulated water flow.

Animals↗
PubMed1986

Ontogeny of natural killer cell activity and antibody dependent cell mediated cytotoxicity in pigs.

Cells from pigs of various ages were collected from peripheral blood, mesenteric lymph node, spleen and thymus and their ability to mediate antibody-dependent cell-mediated cytotoxicity (ADCC) and natural killer (NK) cell activity was determined. ADCC against chicken red blood cell (CRBC) was present in cells from peripheral blood, lymph node and spleen, but was absent in thymic cells. There were no age-related differences in ADCC to CRBC and cells from fetal pigs had similar activities to cells from adult pigs. Maximal cytotoxicity against CRBC was found in the polymorphonuclear leukocyte (PMN) cell fraction. In contrast to the good response against CRBC, PMN cells were not lytic in the ADCC assay when PI3 virus-infected cells were used as target cells. Peripheral blood lymphocytes (PBL) had low but significant lytic activity against PI3 virus-infected cells in the presence of high concentrations of specific antiserum. NK cell activity against K562 target cells was readily detected in PBL of pigs older than 2 weeks but was not observed with cells from spleen, lymph node or thymus from pigs of any age. PBL of pigs younger than 2 weeks of age had low but detectable NK activity: however, fetal pigs had no NK activity against K562 target cells. In contrast, when PI3 virus infected Vero cells were used as target cells, NK cells were detected in spleen and PBL, but not lymph nodes or thymus, of pigs greater than one day of age. Similar to the absence of activity to K562, none of the lymphoid cells from fetal pigs had NK activity against PI3 virus-infected Vero cells. The present results suggest that the effector cells that mediate ADCC are distinct from those that mediate NK activity in that cells mediating ADCC develop earlier and are found in different organs than the NK cells. Additionally, the cells that mediate NK activity against viral infected cells may be different from those that mediate NK activity for K562 target cells; however, regardless of the target, NK cells are not present before birth in the pig.

Age Factors↗
PubMed1986

Effect of corticosteroid on porcine leukocytes: age-related effects of corticosteroid inhibition on porcine lymphocyte responses to mitogens.

The effects of prednisolone sodium succinate on the responses of porcine lymphocytes to phytohemagglutinin (PHA) and pokeweed mitogen (PWM) were investigated. Sensitivity of peripheral blood lymphocytes (PBL) to the synthetic glucocorticoid, prednisolone, was related to age of the lymphocyte donor. The greatest sensitivity was found in PBL from animals less than one week old; PBL from animals between 2 to 4 months retained some glucocorticoid sensitive cells; whereas, PBL from animals older than 6 months were exceptionally resistant to steroid. Similar age-associated sensitivities were found for lymphocytes from lymph node, spleen and thymus. Significant differential sensitivities among the various lymphoid organs were found with the thymic lymphocyte possessing the greatest sensitivity to steroid and the PBL lymph node and splenic lymphocytes possessing the highest resistance to the suppressive effects of steroid. The age related differences in sensitivity to steroid did not appear to be caused by differences in the number of steroid receptors because lymphocytes from susceptible and resistant animals had similar numbers of receptors. The results suggest that the age related sensitivity may be associated with a higher percentage of sensitive thymic-derived lymphocyte in the PBL, lymph node and spleen of the younger animals. Results of this study also suggest that the adult pig (6 months) should be classified as a steroid resistant species.

Aging↗
PubMed1986

Beta-adrenergic-mediated extrarenal potassium disposal in patients with end-stage renal disease: effect of propranolol.

This study was designed to investigate beta-adrenergic-mediated extrarenal potassium disposal in patients with end-stage renal disease (ESRD). Plasma potassium was measured over a period of 3 months in 20 patients with ESRD who were receiving the nonselective beta-blocker propranolol (n = 10) or not (n = 10). Both groups were virtually anuric and had a comparable plasma BUN, plasma bicarbonate, and red cell Na-K-ATPase activity. Plasma potassium measured before dialysis was higher in propranolol users than in nonusers (5.6 +/- 0.2 and 4.6 +/- 0.1 mEq/l, p less than 0.005). To examine beta-adrenergic-mediated internal potassium disposal more directly, epinephrine and epinephrine plus propranolol were acutely administered to another group of patients with ESRD and to normal subjects. Epinephrine resulted in a similar fall in plasma potassium in both groups (0.69 +/- 0.20 and 0.63 +/- 0.07 mEq/l, respectively), thereby suggesting unimpaired beta-adrenergic-mediated extrarenal potassium handling in patients with ESRD. In patients, however, the response to epinephrine was heterogeneous. In 4 of the 10 patients studied, epinephrine infusion did not result in a decrement in plasma potassium suggesting impaired beta-adrenergic responsiveness and thus blunting of this mechanism of extrarenal potassium disposal. In the remaining 6 patients, epinephrine infusion resulted in a fall in plasma potassium which was greater than that observed in normal subjects (1.13 +/- 0.14 and 0.63 +/- 0.07 mEq/l, respectively, p less than 0.01). In the presence of propranolol, the infusion of epinephrine did not result in a decrement in plasma potassium in these 6 patients or in the 6 normal subjects (0.04 +/- 0.07 and -0.02 +/- 0.06 mEq/l, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Antagonists↗
PubMed1984

Intracranial metastases in the initial staging of bronchogenic carcinoma.

We evaluated the effectiveness of neurologic examination, electroencephalography (EEG), and computed tomography (CT) in the initial staging of patients with nonsmall cell carcinoma. Eight of 66 patients had evidence of intracranial metastases. Three of these had no other metastases and would otherwise have been surgical candidates. Thus, thorough investigation for evidence of intracranial metastases is warranted at the time of initial staging. The CT proved to be more effective than clinical evaluation or EEG, alone or in combination, in detecting intracranial metastases. The CT screening of patients prior to curative resection should increase the success rate for such procedures by eliminating patients with preexisting metastases.

Brain Neoplasms↗
PubMed1984

Stroke rehabilitation: correlation and prognostic value of computerized tomography and sequential functional assessments.

In a 13-month period, 41 selected patients with cerebrovascular accidents were studied utilizing computerized tomography of the brain and the Barthel index in an attempt to correlate findings with final rehabilitation outcome. Parameters that were studied included age, sex, lesion size and location, and functional status on admission, during hospitalization, and at discharge. Multiple regression analysis assessed impact of the five independent variables on functional outcome as measured by predischarge Barthel scores. Initial Barthel scores emerged as the most reliable predictor factor, explaining 64% of the variability. The study suggested that computerized tomography scans of the brain are presently not as reliable predictors as sequential functional assessments and should be considered as an adjunct measure.

Activities of Daily Living↗
PubMed1983

Bilateral intracavernous carotid aneurysms mimicking a prolactin-secreting pituitary tumor.

The triad of hyperprolactinemia, ophthalmoplegia, and radiologic abnormalities of the sell turcica suggest a tumor in the area of the pituitary gland. A new association--bilateral intracavernous carotid aneurysms--is presented. Two elderly women had extraocular muscle palsies and elevated serum prolactin levels of 71 and 32 ng/ml (normal: less than 20 ng/ml). In the former, a high-resolution computed tomography scan made after contrast medium injection was incorrectly interpreted as demonstrating a pituitary tumor; cerebral arteriography revealed bilateral aneurysms. In the other patient, a computed tomography scan after contrast medium injection demonstrated the bilateral aneurysms, and these were confirmed by radionuclide angiography.

Aged↗
PubMed1983

Importance of membrane stabilizing effect in massive overdose of propranolol: plasma level study in a fatal case.

Plasma propranolol levels were measured in a woman who took 3120 mg of propranolol in a suicide attempt. Highest plasma level, measured at the 12th hour, was 1475 ng/ml. Elimination half life was prolonged to 13.8 h. She suffered from coma and profound hypotension, then died on the 20th day. By estimating brain propranolol concentration from the plasma level, and reviewing the clinical pictures of previously reported cases, we propose that central nervous suppression by propranolol, with membrane stabilizing effect as its pharmacological basis, may cause life threatening abnormalities in patients with massive overdose of propranolol.

Action Potentials↗
PubMed1983

Cervical chordoma with intradural invasion. A case report.

An unusual case of cervical chordoma with intradural invasion is presented. Anterior resection of the vertebral body with Kiel (calf) bone grafting was performed. Computer tomographs taken on follow-up, four-and-a-half years later, showed the bone graft to be well incorporated and the residual tumor in arrest.

Animals↗
PubMed1982

Compartmentation of mitochondrial creatine phosphokinase. I. Direct demonstration of compartmentation with the use of labeled precursors.

Mitochondrial creatine kinase was first proposed to act as a functional component in respiratory control in 1966 (Bessman, S. P., and Fonyo, A. (1966) Biochem. Biophys. Res. Commun. 22, 597-602). Since that time, evidence has accumulated to support the theory of a creatine-phosphorylcreatine shuttle mechanism involved in supplying energy for aerobic muscle contraction (Bessman, S. P., and Geiger, P. J. (1981) Science 211, 448-452). To demonstrate directly the interaction between mitochondrial oxidative phosphorylation and that of creatine phosphate synthesis, we have studied the labeling of adenine nucleotides and creatine phosphate with [33P]H3PO4 or [gamma-32P]ATP over a range of adenine nucleotide concentrations incubated with rabbit cardiac and rat skeletal muscle mitochondria. An apparent direct mitochondrial ATP contribution to creatine phosphate synthesis was observed that varied inversely with the total adenine nucleotide present in the reaction system. This reaction of de novo synthesized ATP with creatine phosphokinase prior to equilibration with the total ATP pool was observed regardless of the entry point of electrons from oxidizable substrate into the electron transport chain. This special relation was not observed for added yeast hexokinase in forming glucose 6-phosphate. Mitochondria could not synthesize creatine phosphate in the presence of atractyloside, thus underscoring the requirement for adenine nucleotide translocase-linked transport of ATP prior to reaction with the bound creatine phosphokinase. These studies show that there is coupling or compartmentation of ATP synthesis and transport with creatine phosphate formation in heart and skeletal muscle mitochondria.

Animals↗