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Biomedical subjects

S Yang

Publications and source records attributed to S Yang.

At least 487 records · Page 27Linked to original sources
PubMed1995

Effect of norepinephrine and acetylcholine on outer medullary descending vasa recta.

To examine their responsiveness to norepinephrine (NE) and acetylcholine (ACh), outer medullary descending vasa recta (OMDVR) have been dissected from vascular bundles of the rat and perfused in vitro. Abluminal application of NE produced graded vasoconstriction in a concentration range of 10(-9)-10(-6) M. When applied with NE, ACh at concentrations of 10(-8)-10(-5) M dilated NE-preconstricted OMDVR. In contrast, ACh applied in the absence of NE caused vasoconstriction. ACh-induced vasodilation was blocked by addition of the nitric oxide synthase inhibitor N omega-nitro-L-arginine (L-NNA, 2 x 10(-4) M). L-NNA in the absence of ACh enhanced NE-induced vasoconstriction. Supraphysiological (10(-3) M) L-arginine (L-Arg) reversed the effects of L-NNA, and abluminal application of L-NNA alone resulted in OMDVR vasoconstriction. At concentrations of 10(-6)-10(-3) M, abluminal application of L-Arg produced graded vasodilation of NE-constricted OMDVR. These results suggest that adrenergic and cholinergic innervation could influence OMDVR vasomotor tone to modulate total and regional blood flow to the renal medulla. The data also favor a role for the activity of constitutively expressed nitric oxide synthase to modulate OMDVR vasoactivity.

Acetylcholine↗
PubMed1995

Diffusive transport of solute in the rat medullary microcirculation.

Outer medullary descending vasa recta (OMDVR) permeability to sodium (PNa) is much lower than to urea (Purea). Based on these findings, we hypothesized that sodium and urea diffuse across the OMDFR wall by separate routes. To further test this, we simultaneously perfused OMDVR with 22Na and 36Cl, [14C]urea, [3H]raffinose, or tritiated water. The permeability of OMDVR to 22Na and [3H]raffinose was found to increase markedly and reversibly with perfusion rate. PNa was highly correlated with the permeability to Cl (PCl) and to [3H]raffinose (Praf) (R = 0.90 and 0.95, respectively) but not with Purea (R = 0.23). Praf was also correlated with inulin permeability (PIn) (R = 0.93). The intercepts for the regressions of PNa with PCl and Praf and for Praf with PIn were zero. In contrast, OMDVR with low PNa retained very high diffusional water permeability (PD) and Purea, a finding consistent with separate routes for permeation of those tracers. We previously established that thiourea is a competitive inhibitor of OMDVR urea transport. In the presence of 100 mM thiourea, OMDVR PNa and Purea were correlated (R = 0.71) but retained an intercept much > 0. We conclude that Na, Cl, raffinose, and inulin are likely to traverse the OMDVR wall through a common pathway, whereas specific mechanisms exist to regulate the permeation by urea and water.

Animals↗
PubMed1995

Prostaglandin E2 abrogates endothelin-induced vasoconstriction in renal outer medullary descending vasa recta of the rat.

Endothelins (ET) and prostaglandin E2 are synthesized in the inner medulla by collecting duct epithelium and interstitial cells, respectively. All ascending vasa recta (AVR) blood returns from the inner medulla to the cortex in outer medullary vascular bundles. We reasoned that hormones might influence medullary blood flow by diffusing across AVR fenestrations to modulate vasoconstriction of outer medullary descending vasa recta (OMDVR). To investigate this possibility, OMDVR dissected from vascular bundles were exposed to ET-1, 2, or 3. Each endothelin isoform induced stable vasoconstriction with potency, ET-1 > ET-2 > ET-3 (EC50, 1.8 x 10(-15), 5.9 x 10(-12), and 8.8 x 10(-10) M, respectively). The ETA receptor antagonist BQ-123 and BQ-610 (10(-6) M), as well as an ETA and ETB receptor antagonist combination, attenuated vasoconstriction due to ET-1 (10(-12) M). BQ-123 had no effect on the response to ET-3 (10(-8) M). The ETB receptor antagonist BQ-788 (10(-6) M) attenuated the response to ET-3 (10(-10) M), but not that to ET-1 (10(-12) M). Finally, PGE2 (10(-6) M) reversibly dilated OMDVR preconstricted with ET-1 (10(-12) M) or ET-3 (10(-8) M) but not ET-1 (10(-10) M). We conclude that ET-1,2, and 3 are potent constrictors of OMDVR and the response to ET-1 is mainly ETA receptor subtype mediated, while ET-3 acts via the ETB. PGE2 modulates ET induced constriction. These findings are consistent with interactive feedback and control of medullary perfusion by locally synthesized hormones.

Animals↗
PubMed1995

Additive effects of growth hormone and testosterone on lipolysis in adipocytes of hypophysectomized rats.

The effects of growth hormone (GH) and testosterone, alone or in combination, on the regulation of lipolysis in isolated adipocytes from hypophysectomized rats were investigated. Male Sprague-Dawley rats were hypophysectomized at 50 days of age. One week after operation, hormonal replacement therapy with L-thyroxine and hydrocortisone acetate was given to hypophysectomized rats. Groups of rats were treated with GH (1.33 mg/kg, daily), testosterone (10 mg/kg, once) alone or in combination. After one week of hormonal treatment, adipocytes were isolated from the pooled epididymal and perirenal fat pads and glycerol release after isoproterenol stimulation and 125I-cyanopindolol binding was measured. Hypophysectomy caused a marked decrease in basal and isoproterenol-stimulated lipolysis. There was no effect of testosterone treatment alone on lipolysis, but GH treatment resulted in an increase in isoproterenol-induced lipolysis but not to the levels observed in cells from control rats. Testosterone and GH in combination restored the lipolytic response to isoproterenol. Also 125I-cyanopindolol binding was decreased after hypophysectomy. Testosterone treatment alone and GH treatment alone increased the binding, while in combination the treatment had an additive effect. Affinity was not changed, but the effects seemed to be on receptor number, as determined by Scatchard analysis. Forskolin-stimulated cAMP accumulation in adipocytes was markedly reduced after hypophysectomy. Testosterone treatment alone had no effect. GH treatment alone increased forskolin-stimulated cAMP accumulation, although the level was lower than that found in control rats. The combined treatment resulted in a further increase to levels observed in adipocytes from control rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipocytes↗
PubMed1995

Nitric oxide mediates C5a-induced vasodilation in the small intestine.

OBJECTIVE: This study was designed to investigate the microvascular responses of the small intestine to complement C5a and to define the role of nitric oxide in the C5a-induced response. METHODS: Male Sprague-Dawley rats were anesthetized with pentobarbital, and a loop of small intestine was exteriorized and suffused with Krebs solution. The diameters of large and small arterioles of the small intestinal wall were measured with in vivo videomicroscopy following the application of experimental mediators. Four 1-hr C5a dose-response trials were performed (10(-14) M, 10(-12) M, 10(-10) M, and 10(-8) M). Then, we completed acetylcholine dose-response curves with and without N omega-nitro-L-arginine (N-Arg) to document the adequacy of nitric oxide synthase inhibition. The microvascular response to the topical application of C5a (10(-12) M) was recorded in the presence of 2 x 10(-4) M N-Arg. Additionally, experiments of C5a-induced response with N-Arg were repeated in the presence of L-arginine (L-Arg; the precursor of nitric oxide synthesis) or with systemic administration of superoxide dismutase (SOD). RESULTS: (1) C5a induces a dose-dependent vasodilation in the small intestine, and the maximal vasodilation occurs in A3 arterioles at C5a concentration of 10(-12) M; (2) N-Arg inhibits the Ach-induced vasodilation in the rat small intestine; and (3) L-Arg or SOD partially reverses the inhibitory effect of N-Arg. CONCLUSIONS: Nitric oxide mediates the C5a-induced vasodilation in small intestinal microvessels. Superoxide is, at least partially, responsible for the vasoconstrictor response to C5a in the presence of N-Arg.

Animals↗
PubMed1995

[One hundred twenty years of China's health quarantine service].

China's health quarantine service, initiated in 1873, has experienced a long way of 120 years. This article focuses on the rapid development of all aspects in the quarantine construction of organization, profession and ideology, especially in P. R. China's period of reform. The number of quarantine service has increased from 17 seaport services to 192 services, including seaport, airport and land frontier services (up to the end of 1992). The professional quarantine works has expanded from simple quarantine inspection to comprehensive surveillance of communicable diseases, vector control, imported foodstuff supervision and examination etc. Significant contributions have been made to the prevention of the transmission of communicable diseases into the territory, the improvement of the sanitary condition of frontier ports and means of transportation. Frontier health quarantine is one of the strongest lookout posts of sanitation door of the country. It has become one of the major branches of preventive medicine and one of the key links of international health care cooperation. Health quarantine is being developing and strengthening for new and greater success for the realizatiion of the socialist modernization of our country.

China↗
PubMed1995

[Isolation and identification of Rhodopseudomonas viridis and Rhodopseudomonas sulfoviridis].

Under selective culture conditions, two pure cultures (strain G and strain SG) of the purple nonsulfur photosynthetic bacteria containing bacteriochlorophyll b were isolated from pulp effluent and sludge of sewage treatment plant by means of agar shake dilution. Although the cells of strain G and strain SG contained bacteriochlorophyll b and carotenoids, intra-cytoplasmic membranes were of lamellar type parallel to cytoplasmic membrane, the two strains differ in using various organic carbon sources, depending on reduced sulfur compounds and assimilate sulfate. According to Bergey's Manual of Systematic Bacteriology Volume 3, strain G was identified to be Rhodopseudomonas viridis,, strain SG was identified to be Rhodopseudomonas sulfoviridis.

China↗
PubMed1995

Proteolysis of fusion proteins: stabilization and destabilization of staphylococcal protein A and Escherichia coli beta-galactosidase.

The product yield of staphylococcal Protein A reached only 1.8% of the cell dry weight, while the corresponding value was 14% for a fusion protein composed of Protein A and Escherichia coli beta-galactosidase [1], when produced in the same E. coli host strain, with the same promoter and under identical process conditions. Measurement of the stability of Protein A in vivo showed that it was quickly degraded in the cell with a half-life of 30 min when the protein was expressed alone, but after fusion to beta-galactosidase, the Protein A part became considerably stabilized. In spite of the fast intracellular proteolysis of Protein A, few degradation products could be identified on Coomassie Brilliant Blue-stained SDS/PAGE gels after IgG purification, indicating an even faster degradation of the Protein A fragments. Such degradation products, however, accumulated during incubation of the disintegrated cells. Intracellular degradation intermediates could be demonstrated with the more sensitive Western-blot technique. This technique also revealed that a slow degradation took place not only in the Protein A moiety of the fusion protein, but also in the beta-galactosidase moiety. A control with native beta-galactosidase also showed a weak in vivo proteolysis of this molecule, but it was more stable in free form than in the fused form. This means that the proteolytically very sensitive Protein A was stabilized by fusion with beta-galactosidase, but the originally rather stable beta-galactosidase became slightly more susceptible to proteolysis after the fusion.

Amino Acid Sequence↗
PubMed1995

Altered microvascular responses to C5a in rat striated muscle during two-kidney, one clip renovascular hypertension.

OBJECTIVE: To determine how two-kidney, one clip (2-K,1C) renovascular hypertension alters microvascular responses in rat striated muscle to complement C5a, one of the most important inflammatory mediators. METHODS: 2-K,1C hypertension was induced in male Sprague-Dawley rats. Under anesthesia with pentobarbital (50 mg/kg, intraperitoneally) the cremaster muscle microcirculatory preparation with intact neurovascular connections was studied in vivo by closed-circuit videomicroscopy. Recombinant human C5a was applied topically in the tissue bath at concentrations of 10(-12), 10(-10) and 10(-8) mol/l, consecutively. Changes in the microvessel diameters in small arterioles, large arterioles and venules were measured. RESULTS: In normotensive rats complement C5a induces a significant dilation in small arterioles at low bath concentrations (10(-12) or 10(-10) mol/l), but the dilation is attenuated at a higher concentration (10(-8) mol/l). In contrast, in 2-K,1C hypertensive rats C5a constricts small arterioles at low concentrations (< 10(-10) mol/l) but dilates them at a higher concentration (10(-8) mol/l). Large arterioles and venules have minimal responses to C5a in either normotensive or 2-K,1C hypertensive rats. CONCLUSION: 2-K,1C hypertension dramatically alters C5a-induced microvascular responses in small arterioles. The alteration might be attributable to the enhanced vasoconstrictor mechanisms and impaired vasodilator mechanisms during 2-K,1C renovascular hypertension.

Animals↗
PubMed1995

Hemodynamics after orthotopic liver transplantation: study of associated factors and long-term effects.

Among 68 liver transplant recipients, 190 hemodynamic studies were performed to evaluate the role of sepsis, anemia, acute graft rejection, and persistent portosystemic shunts. The hemodynamic outcome after orthotopic liver transplantation (OLT) in stable patients was also determined. Patients with sepsis showed a significant increase in cardiac index (5.1 +/- 0.9 vs. 3.4 +/- 0.7 L/min m2) and hepatic venous pressure gradient (6.3 +/- 2.9 vs. 3.3 +/- 2.1 mm Hg), compared with patients without sepsis. Cardiac index was higher in patients with, than in patients without, anemia (4.1 +/- 0.6 vs. 3.0 +/- 0.6 L/min m2). The hepatic venous pressure gradient was higher in patients with than in patients without acute graft rejection (5.1 +/- 2.9 vs. 2.6 +/- 1.2 mm Hg). Among patients with acute rejection, the hepatic venous pressure gradient was higher in patients with severe rejection than in those with moderate or mild rejection (7.2 +/- 3.3 vs. 4.6 +/- 2.4 and 2.8 +/- 0.9 mm Hg). In the postoperative period, in patients undergoing transplantation for acute liver failure, the hepatic blood flow was normal and significantly lower than in patients receiving transplant for cirrhosis (1.15 +/- 0.37 vs. 1.96 +/- 0.71 L/min). In patients undergoing transplantation for cirrhosis, cardiac index, azygos, and hepatic blood flows significantly decreased after 1 year compared with the first 6 postoperative months. Multivariate analysis showed that sepsis, anemia, and time after OLT were independent variables influencing cardiac index. Sepsis, time after OLT, and the existence of portosystemic shunts were independent variables influencing hepatic blood flow.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

[Efficacy of poria-polyporus anti-diarrhea oral liquor in treating infantile rotavirus diarrhea: a controlled study with smicta].

The efficacy of Poria-Polyporus Anti-diarrhea Mixture (PPAM) in infantile rotavirus diarrhea with Smicta was observed. In two groups of patients, altogether 60 patients were enrolled. The effective rate in the PPAM group and Smicta groups were 83.33% and 90.00% (P < 0.05) respectively. No statistically significance in respect of the duration of fever and diarrhea. Human rotavirus RNA in stool was detected by PAGE, which showed positive result in 13 patients of PPAM group and 19 in Smicta group. The duration of virus excretion in both group were 2-7 days, which was much shorter than 9-21 days of previous report.

Child, Preschool↗
PubMed1995

[Determination of hyperin in Epimedium koreanum Nakai by HPLC].

A HPLC method for the determination of hyperin in Epimedium koreanum was investigated. The result shows that this method is simple, specific and accurate. The recovery was 97.4% and relative standard deviation was 1.2%. With good reproducibility and wide response linearity, the method can be used for the quality control of this herbal medicine.

Analgesics↗
PubMed1995

Electric acupuncture treatment of peripheral nerve injury.

54 cases of peripheral nerve injury were treated by electric acupuncture and compared with 54 control cases treated with supportive medication. The changes after treatment were observed chiefly by electromyography while sensory and motor improvement were also recorded as auxiliary indicators. The therapeutic results in the acupuncture group were 5 cases cured, 26 markedly effective, 19 improved, and 4 cases failed, a total effective rate of 92.6% in contrast to the 55.6% for the controls. Analysis of the therapeutic results showed that 1) those in the acupuncture group were significantly better than in the control group; 2) nerve injuries should be treated as early as possible; 3) the radial nerve and the common peroneal nerve recovered faster than others; 4) cases not surgically explored recovered faster than those that were, and 5) patients with prompt propagation of the needling sensation recovered significantly faster than those with slow propagation.

Acupuncture Therapy↗
PubMed1995

Labeling and quantitative analysis of six lectin receptors of intracranial gliomas.

The distribution of six lectin receptors, WGA, RCA-1, LCA, PSA, PNA and SBA in 111 human gliomas, 8 human normal brain tissues and 11 reactive hyperplasia of astrocytes was observed by means of avidin-biotin-peroxidase technique. Their grays were also quantified with the image analysis instrument. The results showed that WGA and RCA-1 might be used as markers for distinguishing well-differentiated astrocytomas from the reactive hyperplasia of astrocytes especially the reactivity of astrocytes had a specific feature with RCA-1. The difference in quantities of WGA, RCA-1, LCA, PSA receptors between astrocytomas, ependymomas and oligodendrogliomas, medulloblastomas might conduce to the diagnosis and classification. For astrocytomas, it was also showed that a quantity of LCA and PSA receptors was correlated with the degree of cell differentiation. Therefore, they can be used as valuable markers of the differentiation of astrocytomas.

Astrocytoma↗
PubMed1995

Superior vena cava syndrome revisited.

A clinical review with analysis of prognostic factors, including the impact of the initial management modality, was conducted on 137 patients with superior vena cava syndrome (SVCS) seen at the Veterans General Hospital-Taipei between 1989 and 1993. Malignant diseases account for most of the SVCS in our Chinese patients. Patients received diagnostic intervention for their underlying diseases without obvious complications. Whether or not there is a development of SVCS in lung cancer patients, showed prognostic significance in non-small cell lung cancer (NSCLC) and no significance in small cell lung cancer (SCLC). Those with SVCS as the initial manifestation of malignant disease had a poor prognosis compared to those who developed SVCS later. Survival is best in lymphoma/leukemia patients, followed by malignant thymoma and SCLC, and worst in NSCLC and metastatic cancer. The rapid onset of symptoms from SVCS had a short median survival in lung cancer and significantly compromised survival in SCLC. The overall survival of SCLC with SVCS was not affected, regardless of whether the initial therapy had been radiotherapy or chemotherapy.

Adult↗