Biomedical subjects
Publications and source records attributed to W Yang.
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The clinical and biochemical features of an infant affected by holocarboxylase synthetase deficiency are presented. The patient was the sibling of the deceased child in whose cultured skin fibroblasts the precise enzymatic disorder was first determined. This fact permitted administration of specific therapy in the form of oral biotin, resulting in immediate improvement from impending respiratory failure and shock. The clinical response to biotin was accompanied by recovery of the biochemical mechanisms known to be biotin-dependent, as manifested by disappearance of intermediates in urine and blood. The variability of biotin responsiveness and the diversity of clinical presentation in the patients originally thought to have a deficiency of beta methylcrotonylCoA carboxylase, a biotin-dependent enzyme, raises the question of a separate, specific apocarboxylase defect.
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Poly-alpha-cyanoglycine, a homopolymer synthesized from the N-carboxyanhydride of alpha-cyanoglycine, is converted by cumulative reaction of hydrogen cyanide to heteropolypeptides that can be hydrolyzed to protein amino acids, including glycine, alanine, valine, aspartic acid, and glutamic acid. These results are consistent with the hypothesis that the original heteropolypeptides on the earth arose spontaneously from hydrogen cyanide and water without the intervening formation of alpha-amino acids.
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Soluble extracts of mouse cells with Fv-1(n) or Fv-1(b) gene alleles specifically and reciprocally inhibit infection of B- or N-tropic mouse leukemia viruses in permissive cell cultures. NB-tropic virus infection was not inhibited by either cell extract. Extracts from Fv-1(-) cells did not inhibit infection by the three virus host-range types, but N- or B-tropic virus infection of Fv-1(-) cells was inhibited by extracts of the nonpermissive cells, and Fv-1(nb) cell extracts inhibited both viruses. The maximum degree of inhibition was 50-80% as determined by immunofluorescent or plaque assays, with extracts containing up to 500 mug/ml of nonpermissive cell protein. The inhibitor(s) is relatively unstable since activity is lost after 2 hr at 37 degrees or 30 min at 56 degrees . The inhibitor(s) was most effective if added 2 hr before or within 2 hr after infection, did not react with the virus directly, inhibit virus attachment, or inhibit the normal cell functions tested. These results indicate that nonpermissive mouse cells contain a product, possibly determined by the Fv-1 gene, which inhibits some early postpenetration event(s) in leukemia virus infection.
The two-iron-sulphur co-ordination centre in plant and algal ferredoxins is considered as a collection of charged ions whose net negative charge is twice that of the one-iron-sulphur protein rubredoxin. Calculation of the electrostatic free-energy changes for reduction of the two types of proteins indicates that the redox potential of the two-iron-sulphur proteins should be more negative than that of the one-iron-sulphur protein and that in biological systems the ferredoxins should function as one-electron transfer proteins.
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Primary cultures of rabbit corneal epithelial cells have been developed as an in vitro system to predict irritancy potential and delayed cytotoxicity of surfactants in our laboratory. The objective of this study was to evaluate the effects of the surfactant sodium dodecyl sulfate (SDS), a common ingredient in consumer products, on intracellular Ca2+, pH, and mitochondrial function in this culture system. Ca2+ and pH were measured in single living corneal epithelial cells by ratio imaging of fura-2 and 2,'7'-bis(carboxyethyl)-5(6)-carboxyfluorescein fluorescence, respectively. Mitochondrial function was examined by probing mitochondrial membrane potential with the fluorescent dye rhodamine 123 and by measuring the ratio of ATP to ADP with an HPLC method. Cell viability was determined by fluorescence imaging of propidium iodide in single cells and LDH leakage assay in populations of cells. SDS (40 micrograms/ml) increased intracellular Ca2+ from 180 +/- 28nM to 453 +/- 86 nM within 2 min, and induced intracellular acidification (pHi dropped 0.3 units in 15 min). Treatment of the cultures with SDS also resulted in dissipation of the mitochondrial membrane potential and decrease of intracellular ATP/ADP. SDS-induced Ca2+ elevation and intracellular acidification preceded the loss of cell viability observed 20 min after exposure. However, SDS-induced cell injury does not appear to be triggered by extracellular Ca(2+)-influx, as absence of extracellular Ca2+ did not attenuate SDS-induced cytotoxicity while it completely blocked ionomycin-induced cytotoxicity.(ABSTRACT TRUNCATED AT 250 WORDS)
This study evaluated the 12 kDa (smallest) subunit of Echinococcus granulosus antigen B as a diagnostic molecule. Using immunoblotting, 90.9% of cystic hydatid patients, 40% of alveolar hydatid patients and 5.5% of cysticercosis patients showed sero-reactivity to this subunit. Human antibody response to the 12 kDa molecule appeared independent of factors such as parasite strain or host population responsiveness. The majority of infection sera, and some normal human controls, also recognized the 38 kDa subunit of antigen 5.
Interporous hydroxyapatite ceramic (Ca10(PO4)6(OH)2) has excellent bio-compatibility and interlinked pore structure, antibiotics could be loaded into pores in vacuum system. To confirm penetration of the agent to the HAb (2 cm3 cubic block), the aminoglycoside antibiotic (Isepamicin Sulfate; ISP) dissolved in eosin dye at various vacuum pressures. In ISP slow release study, the blocks were placed in 5 ml of PBS at a temperature of 37 degrees C. The PBS was replaced every 48 h and samples containing released ISP were stored until assay. All were found to release the drug maintaining a mean concentration of 0.41 microg ml(-1) even after 18 days of nine exchanges. This concentration of antibiotic exceeded the minimum inhibitory concentration against the common causative organisms of osteomyelitis. The results suggest that HAb impregnated with antibiotics using a simple vacuum system may serve as a valuable new method of administering local chemotherapy, primarily when used as a strut graft for bone defects.
Inclusion of albumin in the perfusate has been previously shown to be detrimental to liver function, but its effect on hepatic vascular reactivity remains unknown. The aim of this study was to determine the effects of albumin on hepatic arterial vascular reactivity and liver viability in the isolated dual-perfused rat liver. A total of 12 rat livers were perfused with Krebs-Bülbring buffer without (Group 1) and with (Group 2) addition of 1% bovine serum albumin (BSA) through the hepatic artery and portal vein for up to 5 h. Hepatic arterial responses to acetylcholine and sodium nitroprusside were studied at 30-min intervals. Liver viability was assessed by bile volume production, release of aspartate serine aminotransferase (AST) and lactic acid dehydrogenase (LDH), and histological examination. Hepatic arterial responses to acetylcholine were significantly attenuated in Group 2. No significant differences in sodium nitroprusside responses were noted. However, bile volume production in Group 2 was significantly decreased compared to Group 1. Effluent AST and LDH release increased significantly in Group 1 but not in Group 2. Histological results showed that sinusoidal endothelial cells and hepatocytes were well preserved without significant deterioration in either group, although there was a marked decrease in vasodilatation to acetylcholine in Group 2. This data suggested that the presence of albumin in the perfusate did not improve retention of smooth muscle reactivity and reduced endothelium-dependent vasodilatation and bile volume production during perfusion. However, improved liver parenchymal cell function was observed.
The purpose of this paper is to provide scientific basis for a unified standard reference value of haematocrit in young people in China. The reference values of haematocrit levels in healthy young people have been collected according to the Wintrobe methods; the relationship between the reference values of haematocrit in young people and altitude has been tested in this paper. It has been found that the reference value of haematocrit in young people increases when the altitude gradually increases, and such relationship is quite significant, The method of mathematical univariate regression analysis is used to deduce two regression equations: Y1 = 44.3 + 0.00357X +/- 3.7, and Y2 = 39.7+0.00318X +/- 2.6. If the altitude value of a s known, the particular area of China is known, the reference value of haematocrit in young people there can be calculated by means of the regression equations. Furhermore depending on the altitude, China can be divided into three districts: Qingzang District, Central District and Eastern District.
Budesonide, a topical corticosteroid used in the treatment of seasonal allergic rhinitis, can be administered to the nose as an aerosol via a pressurized metered dose inhaler (pMDI) or as a metered nasal pump spray. Studies have shown that about 64% (256 micrograms) of a nominal dose of 400 micrograms budesonide pMDI preparation is delivered to the patient compared with 100% of the nominal dose of the pump spray. The present study was undertaken to assess the efficacy and safety of budesonide delivered via a nasal pMDI twice daily (Rhinocort pMDI, at 400 micrograms/day) with an aqueous suspension of budesonide delivered via a metered nasal pump spray once daily (Rhinocort Aqua, at 256 micrograms/day or 400 micrograms/day). The multicenter, double-blind, randomized, placebo-controlled, parallel-group study was conducted in 318 patients (154 men, 164 women; aged 12-67 years) with ragweed-induced seasonal allergic rhinitis. A 1-week baseline period was followed by a 3-week treatment. Nasal symptoms were recorded by the patients, adverse events were noted, an overall evaluation of treatment efficacy was made, and urine cortisol and creatinine levels were measured. Substantial or total control of symptoms was achieved in 83.8% of patients treated with 256 micrograms of aqueous budesonide, 76.3% with 400 micrograms of aqueous budesonide, and 80.8% with 400 micrograms of budesonide pMDI; these were all significantly different (p < 0.001) compared with placebo (23.4% of patients). There were no significant differences in the 24-hour urine cortisol levels between the groups and there were few, infrequent adverse events, similar between the groups and resolved completely on discontinuation of treatment. It was concluded that budesonide, given once daily as 256 micrograms or 400 micrograms in an aqueous suspension or twice daily as 400 micrograms in a pMDI provides good alleviation of the symptoms of seasonal allergic rhinitis with no significant risk of suppression of urine cortisol.