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Biomedical subjects

X C Wang

Publications and source records attributed to X C Wang.

At least 73 records · Page 4Linked to original sources
PubMed1994

[Surgical treatment of pituitary adenoma].

Seventy-four patients with pituitary adenoma were treated by surgery, including 51 transsphenoidal and 23 transcranial approaches, without death, postoperative leakage of CSF and early-period intracranial infection. Many patients had a transient diabetes insipidus after operation. In discussion we attended the difference of attacking age of pituitary adenoma between male and female, the significances of CT and MRI as well as the indication and the important points of various approaches.

Adenoma, Acidophil↗
PubMed1994

Dominance of activated T cells and interleukin-6 in aqueous humor in Vogt-Koyanagi-Harada disease.

PURPOSE: To determine the immunopathologic role of the lymphocytes and lymphokines in aqueous humor (AH) of patients with Vogt-Koyanagi-Harada disease (VKH). METHODS: The distribution of leukocyte subsets in the peripheral blood and AH was examined using fluorescein isothiocyanate-conjugated monoclonal antibodies. The levels of lymphokines, such as interleukin-2 (IL-2) and interleukin-6 (IL-6), in the sera, AH, and cerebrospinal fluid from the patients with VKH were determined using an enzyme-linked immunosorbent assay. RESULTS: T cells constituted the majority of lymphocytes within AH. The value for CD4+ cells (helper/inducer T lymphocytes) in AH was 51.7% +/- 14.9% (mean +/- SD) and that for CD8+ cells (cytotoxic/suppressor T lymphocytes) was 31.1% +/- 13.0%. The percentage of HLA-DR+ cells (B lymphocytes, monocytes, macrophages, and activated T lymphocytes) in AH (50.8% +/- 24.9%) significantly exceeded (P < 0.001) that in blood (13.1% +/- 4.2%). The percentage of CD8+ cells in AH from three patients with the delayed type of VKH rose during their clinical course. The level of IL-6 was significantly elevated in AH from the patients with VKH. The level of IL-6 in AH correlated with the number of lymphocytes in AH, and it reflected the severity of the inflammatory response in AH of patients with VKH. The level of IL-2 in the sera, AH, and cerebrospinal fluid was in the normal range. CONCLUSIONS: Aqueous humor lymphocytes from the patients with VKH were more activated than were peripheral blood lymphocytes. IL-6 may play an important role as an inflammatory mediator in VKH. It may be useful to analyze the lymphocyte subsets and the levels of lymphokines, especially of IL-6, at the site of inflammation in uvea to improve the criteria for assessing the prognosis of VKH.

Adult↗
PubMed1993

Is 5-hydroxytryptamine mediating descending inhibition in the neonatal rat spinal cord through different receptor subtypes?

The long-lasting descending inhibition of lumbar segmental reflexes in the neonatal rat spinal cord has been investigated in vitro by recording from lumbar ventral roots on stimulation of a single lumbar dorsal root. Descending inhibition was elicited by a single stimulus to the latero-ventral thoracic cord. A number of strategies were used to clarify the role of 5-hydroxytryptamine (5-HT) in inhibiting the monosynaptic reflex, the ipsilateral polysynaptic response and the contralateral fast response evoked on the opposite side of the lumbar cord. The 5-HT uptake inhibitor, citalopram (10 nM), potentiated both short-interval (0.5-2 s) inhibition and long-interval (5-100 s) inhibition of the monosynaptic reflex, and also inhibition of the polysynaptic response 10-100 s after the thoracic stimulus. Inhibition of the monosynaptic reflex was blocked by ketanserin (1 microM), spiperone (1 microM) and methiothepin (1 microM), but not by spiroxatrine (0.1 microM) or sulpiride (1 microM). Sumatriptan (20 nM) and methysergide (10 nM) enhanced inhibition of the monosynaptic reflex 0.2-1 s after the thoracic stimulus. It was concluded that 5-HT acting through 5-HT2A/2C receptors is the transmitter responsible for monosynaptic reflex inhibition, at intervals of 0.5-100 s, but a stronger stimulus to the thoracic cord may elicit a non-serotonergic component at intervals of 0.1-2 s. There was no unequivocal evidence that endogenous 5-HT activates 5-HT1 receptors to produce inhibition.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Symmetry-based inhibitors of HIV protease. Structure-activity studies of acylated 2,4-diamino-1,5-diphenyl-3-hydroxypentane and 2,5-diamino-1,6-diphenylhexane-3,4-diol.

The structure-activity relationships in two series of novel, symmetry-based inhibitors of HIV protease, the enzyme responsible for maturation of the human immunodeficiency virus, are described. Beginning with lead compounds 3-6, the effect of adding polar, heterocyclic end groups to one or both ends of the symmetric or pseudosymmetric inhibitors was probed. Aqueous solubility was enhanced > 1000-fold while maintaining potent inhibition of purified HIV-1 protease and anti-HIV activity in vitro. Pharmacokinetic studies in rats indicated a substantial difference in the absorption properties of mono-ol-based and diol-based inhibitors. The oral bioavailability of inhibitor 19 in rats was 19%; however, the Cmax obtained failed to exceed the anti-HIV EC50 in vitro. Substantial plasma levels of potent inhibitors of the diol class were not obtained after oral administration in rats; however, the optimal combination of aqueous solubility and in vitro antiviral activity of several inhibitors support their potential use in intravenous therapy.

Amino Alcohols↗
PubMed1992

Sequences in both class II major histocompatibility complex alpha and beta chains contribute to the binding of the superantigen toxic shock syndrome toxin 1.

Class II major histocompatibility complex (MHC) molecules present peptides derived from processed antigen to antigen-specific CD4-positive T cells. In addition, class II molecules bind with high affinity another class of antigens, termed superantigens. T cell stimulation by superantigens depends almost exclusively on the V beta segment expressed by the T cell receptor (TCR). Mapping of the superantigen binding site on class II molecules should provide valuable information on how MHC and TCR molecules interact. Recombinant mouse I-A class II molecules expressed on transfected L cells were analyzed for their ability to bind the toxic shock syndrome toxin 1. Polymorphic residues in the alpha helices of both the alpha and beta chains of I-A contributed to quantitative toxin binding, suggesting that the toxin binds to either a combinatorial or a conformational site on class II MHC molecules.

Animals↗
PubMed1992

Kinetics of the course of inactivation of aminoacylase by 1,10-phenanthroline.

The kinetic theory of the substrate reaction during modification of enzyme activity previously described [Tsou (1988) Adv. Enzymol. Relat. Areas Mol. Biol. 61, 381-436] has been applied to a study on the kinetics of the course of inactivation of aminoacylase by 1,10-phenanthroline. Upon dilution of the enzyme that had been incubated with 1,10-phenanthroline into the reaction mixture, the activity of the inhibited enzyme gradually increased, indicating dissociation of a reversible enzyme--1,10-phenanthroline complex. The kinetics of the substrate reaction with different concentrations of the substrate chloroacetyl-L-alanine and the inactivator suggest a complexing mechanism for inactivation by, and substrate competition with, 1,10-phenanthroline at the active site. The inactivation kinetics are single phasic, showing that the initial formation of an enzyme-Zn(2+)-1,10-phenanthroline complex is a relatively rapid reaction, followed by a slow inactivation step that probably involves a conformational change of the enzyme. The presence of Zn2+ apparently stabilizes an active-site conformation required for enzyme activity.

Amidohydrolases↗
PubMed1992

[Effect of radix Salviae miltiorrhizae on calcium, zinc, copper content in serum, callus and bony tissue in early stage of healing process in rat closed tibial fracture].

Changes of calcium, zinc, copper contents in serum, callus and bony tissue in the early stage of the healing process of rat closed tibial fracture, also the changes of them with radix Salviae miltiorrhizae (RSM) treatment were studied. It was found that calcium, zinc contents and Zn/Cu ratio increased significantly and the rise of serum copper content was inhibited by the administration of RSM after fracture. Zn/Cu ratio in fracture callus was correlated to the calcium content in fracture callus. These findings suggested that the effect of the promotion of RSM on fracture healing was related to the increased zinc content in serum, also related to the acceleration of mobilization of zinc in fractured bone, and to the acceleration of fracture callus formation and mineralization process by the increased zinc and Zn/Cu ratio in the callus of the fracture.

Animals↗
PubMed1991

Antiviral and pharmacokinetic properties of C2 symmetric inhibitors of the human immunodeficiency virus type 1 protease.

Specific processing of the human immunodeficiency virus (HIV) gag and gag-pol polyprotein gene products by the HIV protease is essential for the production of mature, infections progeny virions. Inhibitors of HIV protease block this maturation and thus prohibit the spread of HIV in vitro. Previously, we reported a series of novel, symmetric inhibitors of HIV protease designed to match the C2 symmetric structure of the active site of the enzyme. In response to the poor aqueous solubility of those lead compounds, we designed a series of analogs with substantially improved (greater than 10(4) fold) solubility. These inhibitors showed anti-HIV activity in H9 and MT4 cells at 0.05 to 10 microM, and in most cases, they were noncytotoxic at concentrations in excess of 100 microM. Further examination of one inhibitor (A-77003) revealed broad-spectrum activity against both HIV types 1 and 2, including azidothymidine-resistant HIV, in a variety of transformed and primary human cell lines. After administration of the inhibitors to rats, short half-lives and, with two notable exceptions, moderate oral bioavailability were observed. Additional pharmacokinetic studies in dogs and monkeys revealed the potential utility of A-77003 as an intravenous anti-HIV agent.

Amino Acid Sequence↗
PubMed1991

Stereocontrolled synthesis of psi[CH = CH] dipeptide isosteres.

A new stereocontrolled synthesis of the psi[CH = CH] dipeptide isostere is described. They key step of the sequence relies on the stereospecific alpha-alkylation of delta-amino-gamma-mesyloxy-alpha,beta-unsaturated esters. The broad availability of nucleophilic alpha-side chains by this method allows the preparation of a wide variety of psi[CH = CH] isosteres with predictable stereochemistry.

Alkylation↗
PubMed1991

[Complete urethral rupture caused by pelvic fracture in females].

Complete urethral rupture caused by pelvic fracture in females is rare. In China except 6 cases treated at other institutions, we encountered 3 case of this kind injury from 1987 to 1989. Reviewing the etiology, diagnosis and treatment of the injury of 9 cases, we suggest that urethral reunion, traction by Foley's catheter and cystostomy should be performed routinely to raise the cure rate.

Adolescent↗
PubMed1991

[Direct vision internal urethrotomy in the treatment of urethral stricture or atresia].

From 1988 to 1990, 30 cases of urethral stricture or atresia were treated with direct vision internal urethrotomy (DVIU). Postoperative follow-up showed recovery of normal voiding in 25 cases, need of irregular urethral dilatation in 2 and failure in 3. Early management of urethral injury is emphasized and the causes of DVIU failure are discussed. We consider that the success rate of DVIU can be further increased.

Adolescent↗
PubMed1990

Transcriptional regulation of the liver beta-galactoside alpha 2,6-sialyltransferase by glucocorticoids.

Hepatic expression of the beta-galactoside alpha 2,6-sialyltransferase is at least in part specified by circulatory glucocorticoids. In this report we use the glucocorticoid agonist, RU362, and the antagonist, RU486, to demonstrate the participation of the glucocorticoid receptor pathway in beta-galactoside alpha 2,6-sialyltransferase regulation. The existing pool of sialyltransferase mRNA is turned over with an approximate half-life of 13 h, and presence of dexamethasone does not alter this rate of degradation. By means of nuclear run-off assays and measurement of nuclear unprocessed transcripts we demonstrate that dexamethasone induction of beta-galactoside alpha 2,6-sialyltransferase mRNA in rat Reuber H35 cells is mediated by a transcriptional enhancement mechanism. The same initiation site is utilized for sialyltransferase transcription in both basal- and hormone-stimulated synthesis. Sialyltransferase sequences residing upstream of this transcriptional initiation point are used to control chloramphenicol acetyltransferase expression in fusion constructs following transient transfection into H35 cells to demonstrate the presence of a functional promoter. Although no element with similarity to the known GRE consensus sequence resides within this promoter region, chloramphenicol acetyltransferase expression under the control of the sialyltransferase promoter is subject to a low (1.6-fold) but reproducible induction in response to dexamethasone. Implications of this observation to glucocorticoid regulation are discussed.

Animals↗
PubMed1990

Design, activity, and 2.8 A crystal structure of a C2 symmetric inhibitor complexed to HIV-1 protease.

A two-fold (C2) symmetric inhibitor of the protease of human immunodeficiency virus type-1 (HIV-1) has been designed on the basis of the three-dimensional symmetry of the enzyme active site. The symmetric molecule inhibited both protease activity and acute HIV-1 infection in vitro, was at least 10,000-fold more potent against HIV-1 protease than against related enzymes, and appeared to be stable to degradative enzymes. The 2.8 angstrom crystal structure of the inhibitor-enzyme complex demonstrated that the inhibitor binds to the enzyme in a highly symmetric fashion.

Amino Acid Sequence↗
PubMed1990

Is the subunit the minimal function unit of creatine kinase?

The dimeric rabbit muscle isozyme of creatine kinase (MM) is modified by iodoacetamide to produce the inactive dimer (M'M') and then hybridized with native dimeric brain isozyme (BB). The hybrid enzyme (M'B), as isolated by PAGE, has the same Km for both ATP and creatine but half the specific activity of the brain isozyme (BB). Likewise, the hybrid of the modified brain with the native muscle isozyme (MB') has half the activity of the native muscle enzyme. The M'B, MB' and MB hybrid dimers all have essentially the same electrophoretic properties, and their intrinsic fluorescence and CD spectra in the far-ultraviolet region are very similar to those of the homodimers MM and BB. Similar results were obtained for the hybrid (M"B) containing the muscle enzyme subunit modified at both the thiol group with iodoacetamide and the Trp residue with dimethyl(2-hydroxy-5-nitrobenzyl)sulfonium bromide and the native brain enzyme submit. The above results suggest strongly the independent catalytic function of the subunit of creatine kinase.

Animals↗
PubMed1990

Epidemic non-A, non-B hepatitis in Xinjiang. Clinical and pathologic observations.

131 cases of epidemic hepatitis from two villages in Xinjiang, were admitted to the provisional infectious diseases hospital from February to April 1987. In 125 (95%) patients neither anti-HAV IgM nor anti-HBc IgM were positive. 118 (90%) were drinking water from a local stream of the Hotan River. The study was conducted on 125 patients aged from 5 to 90 years, with a mean of 26.4 years. There were slightly more males than females, a ratio of 1.5 to 1. The incubation period was roughly estimated to be 17 to 37 days (mean 24.8 days). All subjects were jaundiced. 12 patients (including 6 pregnant women) had cholestatic symptoms. Except one woman who died of postpartum bleeding, all patients ran a benign course without fulminant hepatic failure. Pathologic changes of liver biopsies from 35 cases included lobular damage and inflammation, ballooned hepatocytes with clear cytoplasm and delineated cell membrane which were named "clear cell". There were cholestasis of different degrees in the acute icteric stage and fatty changes in the convalescent stage. It was seen under the electron microscope that the livers of 8 cases had neither tubular structure nor sponge-like inclusions, but had nuclear changes including curled edge of nuclear membrane and nuclear heterochromatin condensed in masses. Liver biopsies were repeated in 7 cases followed up for 6-13 months, and hepatohistology was normal in 5. Of the other two cases there was one of each.

Adolescent↗
PubMed1990

[Xanthogranulomatous pyelonephritis complicated by urolithiasis in upper urinary tract].

Twelve cases of xanthogranulomatous pyelonephritis (XGPN) complicated by urolithiasis in upper tract were presented in this study. Fifty-four cases of XGPN, including 12 cases of this study, reported in China were clinically analysed in the article. All cases were with one suffered kidney, 57.4% of the cases had both XGPN and urolithiasis, 27.8% had the history of urinary infections, 99.0% had function-impaired kidney or renal failure. XGPN was frequently mis-diagnosed as renal cancer, renal tuberculosis and renal abscess etc. The diagnosis and treatment of XGPN are discussed.

Adult↗
PubMed1989

Tissue-specific expression of beta-galactoside alpha-2,6-sialyltransferase. Transcript heterogeneity predicts a divergent polypeptide.

The beta-galactoside alpha-2,6-sialyltransferase represents a member of a family of sialyltransferases which catalyze the terminal addition of sialic acid to maturing carbohydrate chains. We surveyed rat tissues using cDNA probes complementary to coding and noncoding domains of the rat liver alpha-2,6-sialyltransferase. In addition to the expected differences in the level of sialyltransferase mRNA among the tissues, there were dramatic qualitative differences as well. Hepatic sialyltransferase probes hybridize to mRNAs of varying size on Northern blots. A tissue-dependent pattern of expression of these transcripts is documented. Evidence is presented that the multiple transcripts are generated from a common gene sequence. At least one instance of alternate splicing in the generation of the kidney sialyltransferase transcripts is predicted by S1 nuclease analysis. We report the isolation of a rat kidney cDNA clone, RKA, that substantiates this tissue-specific alternate splicing event. The RKA insert, although less than full-length, apparently encodes a polypeptide divergent from the reported hepatic alpha-2,6-sialyltransferase (1). RNA blot analysis indicates that the RKA-type transcripts represent a significant proportion of sialyltransferase RNA in rat kidney. Another class of kidney cDNA clones, RKE, is colinear with the hepatic sialyltransferase sequence. RNA blots probed for the divergent and common regions suggest that complex processing pathways are operative in the tissue-specific expression of sialyltransferase mRNA.

Amino Acid Sequence↗