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W Yang

Publications and source records attributed to W Yang.

At least 523 records · Page 29Linked to original sources
PubMed1993

Purification and characterization of a phosphatidylinositol 4-kinase activator in carrot cells.

A phosphatidylinositol 4-kinase activator (PIK-A49) has been purified from carrot cells grown in suspension culture. The activator was purified from a soluble fraction using DEAE-Sepharose CL-6B and S-Sepharose chromatography columns. PIK-A49 has a relative molecular mass of 49 kDa determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The A50 for the activation of the Triton X-100-solubilized phosphatidylinositol 4-kinase fraction was 0.1 microM. Maximal activation was 3-4-fold. The analysis of the sequences of seven peptide fragments containing a total of 142 amino acid residues indicated that PIK-A49 was 69% identical to an actin-binding protein (ABP-50) from Dictyostelium and > 90% identical to elongation factor-1 alpha (EF-1 alpha) from carrot, tomato, and Arabidopsis. PIK-A49 bound actin and facilitated actin polymerization. Poly(U)-directed polyphenylalanine synthesis assays indicated that PIK-A49 had EF-1 alpha activity. The EF-1 alpha activity was enhanced by rabbit EF-1 beta gamma. Activation of phosphatidylinositol 4-kinase by a protein that binds actin and that has EF-1 alpha activity provides additional complexity to the signal transduction mechanisms involving inositol phospholipid metabolism.

1-Phosphatidylinositol 4-Kinase↗
PubMed1993

Aspartame is no more likely than placebo to cause urticaria/angioedema: results of a multicenter, randomized, double-blind, placebo-controlled, crossover study.

BACKGROUND: Anecdotes and single case reports have suggested that the high-intensity sweetener, aspartame, may be associated with allergic/hypersensitivity-type reactions. METHODS: We conducted a multicenter, placebo-controlled clinical study to evaluate individuals who had experienced urticaria and/or angioedema allegedly associated with ingestion of an aspartame-containing product. Despite extensive recruiting efforts over 4 years, only 21 subjects could be enrolled. After admission to clinical research units, subjects were given aspartame and placebo in a randomized, double-blind, crossover fashion. Subjects received, on different days, increasing doses (50, 300, 600 mg) of aspartame and placebo at 8:00 AM, 10:00 AM, and noon. Subjects who weighed less than 40 kg received one half of these doses. Conversion products of aspartame, aspartyl-phenylalanine diketopiperazine and beta-aspartame, were also included in the aspartame arm of the study. Positive reactions were defined as urticaria (hives with wheals 4 mm or more in diameter with a collective diameter of at least 15 mm or one or more hives with a wheal of 4 mm or greater with a flare of 8 mm or greater) or as angioedema. RESULTS: According to these criteria, four reactions were observed; two followed aspartame ingestion and two followed placebo ingestion (p = 1.00). The incidence of other adverse experiences was no different after aspartame versus placebo ingestion (p = 0.289). CONCLUSION: These results indicate that aspartame and its conversion products are no more likely than placebo to cause urticaria and/or angioedema reactions in subjects with a history consistent with hypersensitivity to aspartame.

Administration, Oral↗
PubMed1993

Stereospecificity of microbial hydrations of oleic Acid to 10-hydroxystearic Acid.

We recently described a simple method for ascertaining the stereochemical purities of hydroxy fatty acids (S. H. El-Sharkawy, W. Yang, L. Dostal, and J. P. N. Rosazza, Appl. Environ. Microbiol. 58:2116-2122, 1992) based on the H-nuclear magnetic resonance spectral analysis of diastereomeric S-(+)-O-acetylmandelate esters of hydroxystearates. This report describes the stereochemistries of microbial hydrations of oleic acid to 10-hydroxystearic acid by Nocardia aurantia (also known as Rhodococcus rhodochrous) ATCC 12674, Nocardia restrictus ATCC 14887, Mycobacterium fortuitum UI-53387, Pseudomonas species strain NRRL-2994, Pseudomonas species strain NRRL B-3266, and baker's yeast. 10(R)-hydroxystearic acid isolated from Pseudomonas species strain NRRL-2994 was the standard for use in the H-nuclear magnetic resonance spectral technique to permit simple assignments of the absolute configurations of 10-hydroxystearic acid produced by different microorganisms. While the R. rhodochrous ATCC 12674-mediated hydration of oleic acid gave mixtures of enantiomers 10(R)-hydroxystearic acid and 10(S)-hydroxystearic acid, Pseudomonas species strain NRRL-B-3266 produced optically pure 10(R)-hydroxystearic acid. The remaining microorganisms stereoselectively hydrated oleic acid to 10(R)-hydroxystearic acid containing between 2 and 18% of the contaminating 10(S)-hydroxystearic acid.

Journal Article↗
PubMed1993

Cloning, molecular characterization, and functional activity of Schistosoma japonicum glyceraldehyde-3-phosphate dehydrogenase, a putative vaccine candidate against schistosomiasis japonica.

We report the cloning, molecular characterization, and purification of functionally active recombinant glyceraldehyde-3-phosphate dehydrogenase (GAPDH) from the human bloodfluke Schistosoma japonicum. The GAPDH homolog from the related species Schistosoma mansoni has shown correlation of antibody titer to resistance to reinfection. A 1,164-bp cDNA (C1) was isolated from an S. japonicum lambda ZapII cDNA expression library immunoscreened with hyperimmune rabbit serum raised against soluble adult S. japonicum proteins. The open reading frame of C1 encodes a protein of 338 amino acids exhibiting 90% identity to the amino acid sequence of S. mansoni GAPDH. The inferred molecular mass of the protein is 36,589 daltons, and in vitro translation of the cDNA with [35S]methionine produced a radiolabelled band of the predicted size. Antibodies to C1 selected from hyperimmune rabbit serum by affinity purification recognized an S. japonicum protein doublet of 37 kDa but did not cross-react with a corresponding protein in S. mansoni extracts. The S. japonicum GADPH appears to be translated from a single mRNA encoded by a single-copy gene. After subcloning in the QIAexpress vector pQE-10 and subsequent expression, the recombinant protein was purified under nondenaturing conditions and shown to exhibit functional GAPDH enzymatic activity.

Amino Acid Sequence↗
PubMed1993

Close correlation between cytoplasmic Ca++ levels and release of an endothelium-derived relaxing factor from cultured endothelial cells.

We studied whether there is a quantitative relationship between free cytosolic Ca++ levels and the release of an endothelium-derived relaxing factor (EDRF) from cultured fetal bovine aortic endothelial cells (EC). EC pretreated with indomethacin were stimulated by the agonists adenosine triphosphate (ATP), bradykinin (BKN), acetylcholine (ACh) and calcium ionophore (A23187) in various concentrations (10(-8)-10(-5) M), and the amount of EDRF released was determined on the basis of endothelium-free rabbit aortic ring relaxation and cultured smooth muscle cell cGMP content. Changes in intracellular Ca++ concentration ([Ca++]i) in response to the same stimuli were determined by photometric fluorescence microscopy using the fluorescent calcium indicator Fura-2. EC stimulation by ATP and A23187 induced dose-dependent increases in both [Ca++]i and the amount of EDRF released. BKN increased both [Ca++]i and EDRF release upon initial exposure (10(-8)M), but there were no further changes at higher concentrations. ACh induced no significant changes in either [Ca++]i or EDRF release. There was a close quantitative correlation between agonist-induced changes in [Ca++]i and the amount of EDRF released (relaxation response in aortic rings and cGMP levels.) (p < 0.001) Removal of extracellular Ca++ eliminated continuous elevation in both [Ca++]i and the amount of EDRF induced by ATP (10(-5)M), BKN (10(-8)M) and A23187 (10(-6)M). These findings suggest that intracellular Ca++ levels are directly linked to the amount of EDRF released, and that extracellular Ca++ is essential for EDRF release because its influx is involved in the continuous elevation of [Ca++]i.

Acetylcholine↗
PubMed1993

Microbial models of mammalian metabolism: involvement of cytochrome P450 in the N-demethylation of N-methylcarbazole by Cunninghamella echinulata.

1. As previously reported (Yang and Davis 1992), N-methylcarbazole (NMC) is converted to N-hydroxymethylcarbazole (NHMC), and 3-hydroxy-N-hydroxymethylcarbazole (3-OH-NHMC), two relatively stable carbinolamine metabolites by the fungus Cunninghamella echinulata (ATCC 9244). Decomposition of these two carbinolamines yields the corresponding dealkylated metabolites, carbazole and 3-hydroxycarbazole. In the present study, the possible involvement of cytochrome P450 in the requisite N-alkyl hydroxylation reaction was examined. 2. Carbon monoxide, a classical P450 inhibitor, markedly inhibited the formation of NHMC, as did potassium cyanide. 1-Benzylimidazole, piperonyl butoxide and SKF-525A inhibited the formation of both NHMC and 3-OH-NHMC, while beta-naphthoflavone (5,6-benzoflavone) induced their formation. 3. The source of the oxygen atom in the metabolite NHMC was examined by GC/MS analysis of NHMC formed during incubation of NMC in H218O-enriched medium which resulted in no incorporation of labelled oxygen into the metabolite. 4. An intermolecular isotope effect was not observed for the formation of NHMC suggesting that C-H bond cleavage is not a rate limiting step in the formation of this metabolite under the conditions examined. 5. It was concluded that P450 enzymes may be involved in the N-demethylation of NMC catalyzed by this fungal model of mammalian metabolism, and provides further support for biochemical and mechanistic parallels between mammalian metabolism and microbial systems catalyzing phase-1 biotransformations.

Carbazoles↗
PubMed1993

[Laser treatment for the membranous cataract: the significance of pre-laser interferometric acuity].

Laser interferometer was used for the detection of interferometric acuity before and after membranous cataract disruption by Q--switched Nd: YAG laser in 23 patients (23 eyes). There was no significant difference between the interferometric acuity before and after laser surgery (p < 0.05). The postoperative corrected acuity was related positively to the preoperative one (p < 0.05). 65.2% of the eyes had a postoperative corrected acuity better than the postoperative interferometric acuity. These results show that laser interferometric acuity is a valuable method in the evaluation of postoperative visual acuity, but false negative and false positive ones should be considered under some circumstances. The interferometric acuity can be affected by aphakia (high refractive error).

Aged↗
PubMed1993

[Effects of air pollution on health of residents in vicinity of an electrometallurgical factory in Chengdu].

Air pollution in an electrometallurgical plant in Chengdu was monitored in 1988. Results showed that atmospheric TSP and Ni concentrations in the vicinity of the plant were higher than those in control area; and TSP content higher than its health standard level. A population of 262 children was physically examined in the same pollution and control areas in May, 1988. Physical examinations were as follows:otorhinolaryngological examination, skin patch test of Ni and Co, immune function test (including PHA skin test, salivary LZM content), Ni levels in human hair and urine etc. We found that body burdens of Ni in population of pollution area increased because of the pollution of Ni compounds in the atmosphere. Hair Ni content in pollution area was significantly higher than that in control area, and the positive rate of Ni skin patch test was also markedly higher than that in control area. Case history indicated that there was a significant difference in Ni content as detected by otorhinolaryngological examinations between the pollution and control areas. Some measures were suggested to improve the air quality based on the study.

Adolescent↗
PubMed1993

[The comparative analysis of the complications of extracapsular cataract extraction with and without posterior chamber intraocular lens implantation].

Three-hundred and fourteen eyes that underwent extracapsular cataract extraction (ECCE) were analyzed. ECCE with posterior chamber intraocular lens implantation (PC IOL) was performed in 168 eyes and ECCE alone was performed in 146 eyes. The complications and visual acuity were compared in the two groups. The PC IOL group showed a low incidence of complications. In addition, vitreous loss occurred in 2.38%, cystoid macular edema occurred in 0.6%, and visual acuity recovered to 0.5 or better in 97.62% of the eyes. The incidence of complications in the ECCE group was slightly higher. The postoperative visual acuity in the ECCE group was lower than that in PC IOL group.

Adult↗
PubMed1992

Release of carrot plasma membrane-associated phosphatidylinositol kinase by phospholipase A2 and activation by a 70 kDa protein.

Plasma membranes were isolated from carrot (Daucus carota L.) cells grown in suspension culture and treated with phospholipase A2 from snake or bee venom for 10 min. As a result of this treatment, phosphatidylinositol kinase activity was recovered in the soluble fraction. There was no detectable diacylglycerol kinase or phosphatidylinositol monophosphate kinase activity released from the membranes after the phospholipase A2 treatment. Treating the plasma membranes with phospholipase C or D did not release PI kinase activity. The phospholipase A2-released PI kinase was activated over 2-fold by a heat stable, soluble 70 kDa protein. The partially purified 70 kDa activator increases the Vmax but does not affect the Km of the phospholipase A2-released PI kinase.

1-Phosphatidylinositol 4-Kinase↗
PubMed1992

Gene structure and expression of the mouse 5-HT2 receptor.

Serotonin (5-hydroxytryptamine, 5-HT) is an important neurotransmitter which mediates numerous physiological functions. Using the SacI-EcoRI restriction fragment of the rat brain 5-HT2 receptor cDNA as a probe, we have screened a mouse brain cDNA library, created by random priming and constructed in SWAJ vectors, and have isolated a cDNA encoding a 1.4 kb open reading frame which codes for a functional mouse 5-HT2 receptor identified from pharmacological binding profiles and coupling of phosphoinositide formation in a stably transfected fibroblast cell line. The deduced amino acid sequence is 97.4% identical to the rat 5-HT2 receptor. Using the same 5-HT2 receptor cDNA probe, ten positive genomic clones were isolated from two mouse genomic libraries constructed in the pWE15 cosmid vector and the EMBL-3 phage vector. Extensive mapping and sequencing of these genomic clones indicate the mouse 5-HT2 receptor coding region spans over 20 kb and is composed of three exons split by two introns. Northern blot analysis shows one band of 5-6 kb in the mouse brain, but not in the heart, lung, liver, or kidney total RNA. Southern analysis of mouse liver genomic DNA shows a simple pattern of digestion by several restriction enzymes, which suggests that one copy of the 5-HT2 receptor gene may exist in the mouse genome.

3T3 Cells↗
PubMed1992

Normal and abnormal pathfinding of facial nerve fibers in the chick embryo.

Development of the facial nerve was studied in normal chicken embryos and after surgical disruption of ingrowing sensory facial nerve fibers at 38-72 h of incubation. Disruption of facial nerve fibers by otocyst removal often induced a rostral deviation of the facial nerve and ganglion to the level of the trigeminal ganglion. Cell bodies of the geniculate ganglion trailed their deviating neurites and occupied an abnormal rostral position adjacent to the trigeminal ganglion. Deviating facial nerve fibers were labeled with the carbocyanine fluorescent tracer DiI in fixed tissue. Labeled fibers penetrated the cranium adjacent to the trigeminal ganglion, but they did not follow the trigeminal nerve fibers into the brain stem. Rather, after entering the cranium, they projected caudally to their usual site of entrance and proceeded towards their normal targets. This rostral deviation of the facial nerve was observed only after surgery at 48-72 h of incubation, but not in cases with early otocyst removal (38-48 h). A rostral deviation of the facial nerve was seen in cases with partial otocyst removal when the vestibular nerve was absent. The facial nerve followed its normal course when the vestibular nerve persisted. We conclude that disruption of the developing facial pathway altered the routes of navigating axons, but did not prevent pathfinding and innervation of the normal targets. Pathfinding abilities may not be restricted to pioneering axons of the facial nerve; later-developing facial nerve fibers also appeared to have positional information. Our findings are consistent with the hypothesis that navigating axons may respond to multiple guidance cues during development. These cues appear to differ as a function of position of the navigating axon.

Acetylcholinesterase↗
PubMed1992

Cloning and partial nucleotide sequence of Schistosoma japonicum paramyosin: a potential vaccine candidate against schistosomiasis.

Paramyosin from the blood fluke, Schistosoma mansoni, has shown promise as a vaccine candidate for schistosomiasis mansoni. Here we report the cloning and partial nucleotide sequence of a cDNA encoding paramyosin from the related human parasite, Schistosoma japonicum. Affinity purified antibodies to this clone recognized a S. japonicum antigen of molecular weight 97 kDa, equivalent to the reported size of S. mansoni paramyosin. Alignment of the cDNA sequence with that of S. mansoni paramyosin revealed 90% identity. Comparison of the predicted amino acid sequences revealed 95% identity. Although these two parasites differ in many characteristics, the substantial homology demonstrated here between S. mansoni and S. japonicum paramyosin could have important implications for the development of a S. japonicum vaccine.

Amino Acid Sequence↗
PubMed1992

The human 5-HT2 receptor is encoded by a multiple intron-exon gene.

Serotonin (5-hydroxytryptamine; 5-HT) mediates many central and peripheral nervous system functions by its interaction with specific neuronal receptors. Here we report the genomic structure of the human 5-HT2 receptor. The SacI-EcoRI restriction fragment of rat 5-HT2 receptor cDNA was used as a probe to identify and isolate two positive clones of 8.5 and 7.0 kb from an EcoRI restriction digest of a chromosome 13 specific EcoRI fragment lambda-phage human genomic library. Subcloning and sequencing of these fragments showed the 8.5 kb fragment (designated lambda SE-5) contained the first two exons of the 5-HT2 receptor gene. The 7.0 kb insert (lambda SE-2) contained an incomplete third exon. A HindIII-EcoRI fragment of this insert was used as a probe to isolate a 9.0 kb clone (lambda SH-2), which contained the entire third exon, from a chromosome 13 specific HindIII-fragment lambda-phage human genomic library. The isolation of these three clones (lambda SE-5, lambda SE-2 and lambda SH-2) shows that the human 5-HT2 receptor gene consists of three exons separated by two introns and spans over 20 kb. The deduced amino acid sequence of the human, mouse and rat 5-HT2 receptors are highly conserved and all three share a 90% sequence similarity.

Amino Acid Sequence↗
PubMed1992

Production of a toxic, novel mammalian metabolite of N-methylcarbazole predicted by a fungal cell model of mammalian metabolism.

The formation of N-hydroxymethylcarbazole (NHMC), carbazole, 1-hydroxy-N-methylcarbazole, 2-hydroxy-N-methylcarbazole, and 3-hydroxy-N-methylcarbazole as products of mammalian liver microsomal metabolism of N-methylcarbazole (NMC) has been documented by several investigators. In previous studies in our laboratory, the fungus Cunninghamella echinulata (ATCC 9244) produced two new metabolites, 3-hydroxy-N-hydroxymethylcarbazole (3-OH-NHMC), and 3-hydroxycarbazole (3-OH-carbazole), in addition to the known mammalian metabolites, NHMC and carbazole. One of the two novel metabolites isolated from the microbial models, 3-OH-NHMC, was also identified and characterized in rat liver microsomes by analytical (HPLC) and spectral (UV and NMR) comparisons with a reference standard. The two metabolites, 3-OH-NHMC and 3-OH-carbazole, were shown to be cytotoxic to cultured rat hepatocytes as assessed by lactate dehydrogenase (LDH) leakage and neutral red (NR) uptake. These studies demonstrate the prospective potential of microbial models for predicting the formation of metabolites from drugs and other xenobiotics in mammalian systems.

Animals↗
PubMed1992

Microbial oxidation of oleic acid.

Resting cells of Saccharomyces cerevisiae (baker's yeast, type II; Sigma) were used to convert oleic acid into 10-hydroxyoctadecanoic acid with a 45% yield. Nocardia aurantia (ATCC 12674), Nocardia sp. (NRRL 5646), and Mycobacterium fortuitum (UI 53378) all converted oleic acid into 10-oxo-octadecanoic acid with 65, 55, and 80% yields, respectively. Structures of all metabolites were suggested by 1H and 13C nuclear magnetic resonance and by infrared and mass spectrometry. Structures of isomeric hydroxystearate and oxostearate derivatives and the stereochemical purity of hydroxystearates are difficult to prove unambiguously unless authentic standard compounds are available for spectral comparison. We describe the use of the chemical Baeyer-Villiger oxidation technique with 10-oxo-octadecanoic acid followed by mass spectral analysis of neutral extracts as a simple method to confirm the position of oxo-functional groups in the structures of fatty acid ketones. We further introduce a simple method based on 1H nuclear magnetic resonance analysis of diastereomeric S-(+)-O-acetylmandelate esters of hydroxystearates as a means of ascertaining stereochemical purities of hydroxy fatty acids.

Bacteria↗