Biomedical subjects

H Yin

Publications and source records attributed to H Yin.

At least 37 records · Page 2Linked to original sources

PubMed2001

Evidence that HAX-1 is an interleukin-1 alpha N-terminal binding protein.

During studies aimed at understanding the function of the N-terminal peptide of interleukin-1 alpha (IL-1 NTP, amino acids 1-112), which is liberated from the remainder of IL-1 alpha during intracellular processing, we identified by yeast two-hybrid analysis a putative interacting protein previously designated as HAX-1. In vitro binding studies and transient transfection experiments confirmed that HAX-1 can associate with the IL-1 NTP. HAX-1 was first identified as a protein that associates with HS1, a target of non-receptor protein tyrosine kinases within haematopoietic cells. Recent data have also revealed interactions between HAX-1 and three disparate proteins, polycystin-2 (derived from the PKD2 gene), a protein linked to polycystic kidney disease, cortactin, and Epstein-Barr virus nuclear antigen leader protein (EBNA-LP). Sequence analysis of different HAX-1 binding domains revealed a putative consensus binding motif that is present in various intracellular proteins. Overlapping peptides comprising the IL-1 NTP were synthesized, and binding experiments revealed that discrete peptides were capable of interacting with HAX-1. HAX-1 may serve to retain the IL-1 NTP in the cytoplasm, and complex formation between the IL-1 NTP and HAX-1 may play a role in motility and/or adhesion of cells.

Adaptor Proteins, Signal Transducing↗

PubMed2001

Importance of the 3' untranslated region of ornithine decarboxylase mRNA in the translational regulation of the enzyme.

Translational regulation of ornithine decarboxylase (ODC), which catalyses the first step in the biosynthesis of polyamines, appears to be an important mechanism in the strong feedback control as well as in the hypotonic induction of the enzyme. However, the exact mechanisms are not yet understood. The ODC mRNA has long 5' and 3' untranslated regions (UTRs) which may be involved in the translational control of the enzyme. In the present study we have used a series of stable transfectants of Chinese Hamster ovary cells expressing ODC mRNAs with various truncations in the 5' and 3' UTRs to investigate the importance of these regions. It is demonstrated that neither the 5' UTR nor the 3' UTR appears to be involved in the polyamine-mediated feedback control of ODC synthesis. The hypotonic induction of ODC, on the other hand, was shown to be highly dependent on the presence of the 3' UTR, but not on the 5' UTR, of ODC mRNA. Cells expressing ODC mRNAs lacking the 3' UTR showed no, or only a very slight, induction of ODC whether the 5' UTR was present or not, whereas the cell lines expressing ODC mRNAs containing the 3' UTR (with or without the 5' UTR) markedly induced ODC after a hypotonic shock. The present finding of a role for the ODC mRNA 3' UTR in the hypotonic induction of ODC is the first demonstration of a specific effect of the 3' UTR in the regulation of ODC.

3' Untranslated Regions↗

PubMed2001

Entropy-vanishing transition and glassy dynamics in frustrated spins.

In an effort to understand the glass transition, the dynamics of a nonrandomly frustrated spin model has been analyzed. The phenomenology of the spin model is similar to that of a supercooled liquid undergoing the glass transition. The slow dynamics can be associated with the presence of extended stringlike structures which demarcate regions of fast spin flips. An entropy-vanishing transition, with the string density as the order parameter, is related to the observed glass transition in the spin model.

Journal Article↗

PubMed2001

Photoreductive dehalogenation of halogenated benzene derivatives using ZnS or CdS nanocrystallites as photocatalysts.

ZnS nanocrystallites (nc-ZnS) prepared in N,N-dimethylformamide (DMF) photocatalyze dehalogenation of halogenated benzenes to benzene as the final product from chlorinated benzenes and to difluorobenzenes from fluorinated benzenes in the presence of triethylamine (TEA) as an electron donor under UV light irradiation (lambda > 300 nm). When CdS nanocrystallites (nc-CdS) are used as a photocatalyst (lambda > 400 nm), halogenated benzenes are photoreductively dehalogenated, yielding trichlorobenzene from hexachlorobenzene and tetrafluorobenzene isomers from hexafluorobenzene as the final products. Photoformed electrons on nc-ZnS and nc-CdS have such negative reduction potentials that these electrons reduce polyhalogenated benzenes, leading to the successive dehalogenation. nc-ZnS exhibits higher photocatalytic activitythan nc-CdS due to the more negative potential of the electrons on nc-ZnS than that on nc-CdS. The higher activities of nc-ZnS and nc-CdS compared to their bulk forms are explained as being due to their quantum size effects and the adsorptive interaction between the substrates and the nanosized photocatalysts.

Benzene Derivatives↗

PubMed2001

Specific peptide inhibitors of trypanothione reductase with backbone structures unrelated to that of substrate: potential rational drug design lead frameworks.

By introducing cationic charge sites novel peptide lead inhibitor structures for trypanothione reductase have been designed using molecular modelling methods. The inhibitors showed reversible, linear competitive inhibition and the strongest peptide inhibitor to date was found to be N-benzyloxycarbonyl-Ala-Arg-Arg-4-methoxy-beta-naphthylamide with a Ki value of 2.4 microM and a selectivity for parasitic enzyme (trypanothione reductase) over the host enzyme (human glutathione reductase) of over 3 orders of magnitude.

Drug Design↗

PubMed2001

Analysis of diacyl peroxides by Ag+ coordination ionspray tandem mass spectrometry: free radical pathways of complex decomposition.

Organic peroxides have significance in organic synthesis and biological processes. Characterization of these compounds with weak O-O bonds is sometimes difficult due to their thermal instability and sensitivity to acid or base. Coordination of diacyl peroxides with AgBF4 provides a means for analysis of these compounds by coordination ionspray tandem mass spectrometry (CIS-MS/MS). Precursor ion (Q1) scans of acetyl benzoyl peroxide give two Ag+ adducts, [M + Ag + solvent]+ and [M + Ag + M]+. These silver ion adducts can be selectively dissociated (CID) to give unique structural information about the analyte. Decomposition of the [M + Ag + solvent]+ adduct generates fragmentation products due to apparent homolytic cleavage of the O-O bond followed by decarboxylation of the resultant radicals. The bis-diacylperoxide complex, [M + Ag + M]+ gives CID pathways that involve homolysis of the (O-O bond and free radical cross-coupling of the two diacyl peroxides coordinated to the silver ion, i.e. formation of dibenzoyl peroxide, phenyl benzoate, and biphenyl from acetyl benzoyl peroxide. The observation of free radical CID modes is uncommon in mass spectrometry but these pathways are consistent with well-known solution and gas phase processes for peroxide compounds. The proposed fragmentation pathways have been supported by experiments with (18)O and deuterated substrates. This technique can be applied to analyze diacyl peroxides with different substituents as well.

Chromatography, Thin Layer↗

PubMed2001

Comparison of apoptosis and apoptosis-related gene products between extranodal oral B-cell lymphoma and maxillofacial nodal B-cell lymphoma.

Twenty-seven cases of primary extranodal oral B-cell lymphoma and 22 cases of primary maxillofacial nodal B-cell lymphoma were investigated for the presence of apoptotic cells and the expression of apoptosis-related gene products by terminal deoxynucleotidyl-mediated dUTP nick end labeling (TUNEL) and immunohistochemistry. The majority of extranodal oral diffuse large B-cell lymphomas (17/25, 68%) and maxillofacial nodal diffuse large B-cell lymphomas (14/16, 88%) contained no or less than 10% apoptotic cells. Whereas the majority of extranodal oral diffuse large B-cell lymphomas (18/25, 72%) and maxillofacial nodal diffuse large B-cell lymphomas (13/16, 81%) contained more than 10% of Ki-67-positive cells. Bcl-2-, Bax-, p53- and Ki-67-positive rates were higher in maxillofacial nodal diffuse large B-cell lymphomas than in extranodal oral diffuse large B-cell lymphomas, but only Bax (chi2 test, 0.01<P<0.025) and p53 (chi2 test, 0.005<P<0.01) had significant differences. Extranodal oral diffuse large B-cell lymphomas had a higher frequency of TUNEL expression than maxillofacial nodal diffuse large B-cell lymphomas. In maxillofacial nodal diffuse large B-cell lymphomas, stage III and stage IV tumors had a significantly higher frequency of Bcl-2 expression than stage I and stage II tumors (Fisher's exact test, P<0.01). These findings indicated that in the majority of both extranodal oral and maxillofacial nodal diffuse large B-cell lymphomas, apoptosis was inhibited - whereas proliferative activity was accelerated. Impairment of apoptosis and apoptotic related gene products may have a more important relation to maxillofacial nodal diffuse large B-cell lymphoma than extranodal oral diffuse large B-cell lymphoma.

Apoptosis↗

PubMed2001

Efficacy of azimilide and dofetilide in the dog right atrial enlargement model of atrial flutter.

INTRODUCTION: Azimilide dihydrochloride blocks both the rapid (I(Kr)) and slow (I(Ks)) components of the delayed rectified K+ current; dofetilide blocks only I(Kr). Their efficacies were assessed on atrial flutter reentrant circuits in dogs with surgically induced right atrial enlargement. METHODS AND RESULTS: Multiple biopsies of the tricuspid valve and banding of the pulmonary artery in male mongrel dogs made them susceptible, about 3 weeks postoperatively, to stimulation-induced sustained (5 min or longer) atrial flutter. Azimilide 3 mg/kg administered intravenously (i.v.) terminated flutter in 8 of 8 dogs, but a slower, nonsustained arrhythmia could be reinduced in 5. In these 5 dogs, azimilide 10 mg/kg terminated flutter and prevented reinduction. This dose increased effective refractory period significantly more in the slow conduction zone (25%) than in the normal zone (17%) and increased flutter cycle length (37%). Termination followed progressive conduction delay in the slow zone of the reentrant circuit. Dofetilide 1 microg/kg i.v. terminated flutter in 6 of 6 dogs, but the arrhythmia could be reinduced. At 3 microg/kg, flutter terminated in all dogs and could not be reinduced. Dofetilide also increased the effective refractory period significantly more in the slow zone (17%) than in the normal zone (12%) and increased cycle length (33%), leading to interruption of the arrhythmia circuit. CONCLUSION: In the canine right atrial enlargement model of circus movement atrial flutter, both azimilide 10 mg/kg i.v. and dofetilide 3 microg/kg i.v. were 100% effective in terminating flutter and preventing reinduction. Efficacy relied on a similar mechanism of differentially prolonged refractoriness in the slow conduction component of the reentrant circuit where drug-induced termination occurred.

Animals↗

PubMed2001

Differential chromosome behaviour in mammalian oocytes exposed to the tranquilizer diazepam in vitro.

There are several reports demonstrating that aneugens may preferentially affect segregation of particular chromosomes in somatic cells. Much less is known on specific susceptibility of individual chromosomes to non-disjunction in mammalian meiosis in response to chemical exposures. To explore possible chromosome-specific behaviour and susceptibility to errors in chromosome segregation in mammalian oogenesis we employed spindle immunofluoresecence in combination with FISH with chromosome-specific probes to analyse congression of chromosomes X, 8 and 16 in diazepam (DZ)-treated, meiotically delayed meiosis I oocytes of the mouse. Concomitantly, we assessed the susceptibility of homologues to precociously segregate prior to anaphase I during DZ-induced meiotic arrest. About 50% of all oocytes exposed to 25 microg/ml DZ became meiotically delayed. Chromosomes failed to congress at the spindle equator in one-third of these meiosis I oocytes. The X chromosome was significantly more often located away from the spindle equator as compared with the expected random behaviour. Concomitantly, DZ exposure induced untimely segregation of homologous chromosomes of the gonosome and the autosomes in meiosis I. This occurred with similar frequencies. The observations confirm that DZ perturbs cell cycle progression, interferes with chromosome alignment, causes predivision and thus may predispose mammalian oocytes to errors in chromosome segregation. For the first time, chromosome-specific behaviour is reported in female meiosis in response to exposure to an aneugenic chemical.

Anaphase↗

PubMed2001

Strain difference in regulation of pituitary tumor transforming gene (PTTG) in estrogen-induced pituitary tumorigenesis in rats.

Recently a novel oncogene, PTTG (pituitary tumor transforming gene) was isolated from a rat pituitary tumor cell line whose expression is apparently correlated with pituitary tumorigenesis. In the rat, estradiol (E(2)) is known to induce anterior pituitary hyperplasia. The effects of E(2), however, vary greatly among rat strains. Therefore we examined the expression of PTTG and its regulation by E(2) in F344, Wistar, Brown-Norway and Donryu rats. Four-week-old females were ovariectomized and a pellet containing 10 mg of E(2) was given s.c. Total RNA was isolated from the pituitary gland and PTTG mRNA was measured with a competitive RT-PCR technique. The F344 strain was the most susceptible to E(2) induction of pituitary tumorigenesis, followed by Wistar and Brown-Norway, while no increase in pituitary weight was noted in Donryu rats. PTTG mRNA in the gland was induced by E(2) within 48 - 72 h in F344 and Wistar, but not in Brown-Norway or Donryu strains. These data suggest that PTTG expression may at least in part be responsible for strain differences in E(2)-induced pituitary tumorigenesis.

Animals↗

PubMed2001

ET(B) receptor activation causes exocytic insertion of NHE3 in OKP cells.

Endothelin-1 (ET-1) activates sodium/hydrogen exchanger 3 (NHE3) in opossum kidney clone P (OKP) cells expressing ET(B) receptors. ET-1 (10(-8) M) caused a two- to threefold increase in apical membrane NHE3 (assessed by surface biotinylation), in the absence of a change in total cellular NHE3. A maximal effect was achieved within 15 min. The increase in apical NHE3 was not blocked by cytochalasin D but was blocked by latrunculin B, which also prevented the ET-1-induced increase in NHE3 activity. Endocytic internalization of NHE3, measured as protection of biotinylated NHE3 from the membrane-impermeant, sulfhydryl-reducing agent MesNa was minimal within 35 min and was not regulated by ET-1. Exocytic insertion of NHE3, measured as the appearance of biotinylated NHE3 after the blockade of reactive sites with sulfo-NHS-acetate, was increased in response to ET-1. These studies demonstrate that ET-1 induces net trafficking of NHE3 to the apical membrane that is mediated by enhanced exocytic insertion and is required for increased NHE3 activity.

Alkaline Phosphatase↗

PubMed2001

Clinical application of serial operations with preserving spleen.

AIM: To evaluate the clinical application of serial operations with preservation of spleen. METHODS: Serial operations with preserving spleen were performed on 211 cases in our hospital from 1980 to 2000. The patient's age ranged from 13 to 56 years, averaging 38 years. Diseases included splenic injury in 171 cases, portal hypertension in 9 cases, splenic cyst in 10 cases, and the lesion of pancreatic body and tail in 21 cases. RESULTS: All the cases were cured, and 129 patients were followed up from 3 months to 3 years with the leukocyte phagocytosis test, detection of immunoglubin, CT,(99m)Tc scanning and ultrasonography. The results were satisfactory. CONCLUSION: The operations with preserving spleen were safe, feasible, and worth of clinical application.

Adolescent↗

PubMed2001

Localization of EP(1) and FP receptors in human ocular tissues by in situ hybridization.

PURPOSE: To examine the expression and localization of EP(1) and FP receptor mRNAs in normal human ocular tissues by in situ hybridization. METHODS: Digoxigenin-labeled human EP(1) and FP receptor antisense and sense riboprobes were used for in situ hybridization on paraffin sections of normal human eye tissue. RESULTS: In situ hybridization revealed the presence of high levels of both EP(1) and FP receptor mRNA transcripts in the blood vessels of iris, ciliary body, and choroid. Both the endothelial and smooth muscle cells of blood vessels demonstrated intense hybridization signals corresponding to EP(1) receptor mRNA transcript. EP(1) receptor hybridization signals were present in all the muscle fibers of the ciliary body. In the retina, hybridization signals for EP(1) receptors were observed in photoreceptors and both nuclear layers and in ganglion cells. The hybridization signals corresponding to FP receptor transcript were similar to those of EP(1) receptors in the iris tissues. In the ciliary muscle, FP receptor mRNA transcript was predominantly present in the circular muscle and in the collagenous connective tissues; no hybridization signal for this receptor was observed in the retina. CONCLUSIONS: The wide distribution of EP(1) and FP receptor mRNAs in human ocular tissues appears to be localized in the functional sites of the respective receptor agonists. Selective localization of FP receptor mRNA in the circular muscles and collagenous connective tissues of the ciliary body suggests their involvement in the increased uveoscleral outflow of aqueous humor by PGF(2alpha).

Blotting, Northern↗

PubMed2001

Methanol solvent may cause increased apparent metabolic instability in in vitro assays.

Methanol was widely used as a substrate-delivering solvent in in vitro metabolic stability screenings. Its interaction with enzyme activities, particularly those of cytochrome P450s, has been investigated extensively in the past. Little was known about the interaction of methanol, whether direct or indirect, with substrates. The present study provided data for the first time to show that use of methanol may result in the formation of artifacts, which could mislead the metabolic stability information. The disappearance of LAQ094, metaraminol, and (-)-isoproterenol following 1-h incubation with human liver microsomes was 73, 85, and 66%, respectively, in the presence of 1% methanol, but was only 3, 15, and 24%, respectively, in the absence of organic solvent. The dramatically increased instability in the presence of methanol of these three compounds, each with 1,2-diamino or 1,2-amino hydroxy functional groups, was due to the formation of [M + 12] products resulting from condensation reaction of the substrates with formaldehyde. Formaldehyde was formed from methanol by human liver microsomal enzymes with an apparent K(m) of 35 mM and a V(max) of 7.9 nmol/min/mg of protein. The concentration of formaldehyde reached as high as 600 microM following a 60-min incubation. The [M + 12] products were characterized as five-membered heterocycles by liquid chromatography and tandem mass spectrometry analysis. Inclusion of 10 mM glutathione prevented the formation of such artifacts and is therefore suggested for future in vitro screenings. Our study also documented the novel finding of enzyme-dependent conversion of NADPH to nicotinamide in microsomal incubations.

Cytochrome P-450 Enzyme System↗

PubMed2001

[The morphological and histological identification of Boschniakia rossica].

In this paper the descriptions and microscopic characters of Boschniakia rossica were recounted. The evidences of the identication were presented. The differences between Boschniakia rossica and its similar species Cistanche deserticola and Cynomrium songaricum were also summed up. Boschniakia rossica: Stem thin. Cross section hollow, brittle in texture, with cortex. Stele vascular bundles arranged in ring, pith obvious. Cistanche deserticola and Cynomrium songaricum: Stem thick and strong. Cross section solid, without cortex. Hard in texture. Pith unobvious. The stele vascular bundle of Cistanche deserticola arranged in wavy ring. That of Cynomrium songaricum irregularly arranged.

Cistanche↗

PubMed2001

[Activation of NF-kappa B and its effect on induction of platelet-derived growth factor-B transcription by angiotensin II in ECV304 cell line].

OBJECTIVES: The renin-angiotensin system may contribute to the pathogenesis of atherosclerosis. The transcription factor nuclear factor-kappa B (NF-kappa B) participates in most signal pathways involved in the inflammatory process. In this project the effect of angiotensin II (Ang II) on NF-kappa B activation and the promotion of PDGF-B mRNA expression in human endothelial cell line ECV304 was studied. METHODS: Electrophoretic mobility shift assay, immunofluorescence and immunoelectronic microscope techniques, including confocal microscopy and gold particle labelled electronic microscopy were applied to investigate the mechanism by which Ang II activates NF-kappa B, ECV304 cells were transiently transfected with an NF-kappa B/luciferase reporter gene and catalytically inactive NIK, IKK alpha, IKK beta mutants respectively. Northern blot was carried out to detect PDGF-B mRNA. RESULTS: By the findings of immunofluorescence confocal microscopy, immunoelectronic microscopy and Northern blot, Ang II was effective in stimulating NF-kappa B activation and there was definited cytoplasmic-to-nuclear translocation of NF-kappa B subunits p50 and p65 and overexpression of PDGF-B mRNA expression. Over-expression of the transiently transfected IKK alpha-KM, IKK beta-KM and NIK-KM mutant genes enabled to block the reporter gene activation induced by ang II. CONCLUSION: Ang II is effective to activate NF-kappa B through a pathway dependent on NIK, IKK alpha and IKK beta, and induces PDGF-B transcription in the endothelial cell line ECV304.

Angiotensin II↗

PubMed2001

Apolipoprotein E polymorphism in the early onset of coronary heart disease.

OBJECTIVE: To assess the relationship between apolipoprotein E (apoE) polymorphism and the early onset of coronary heart disease (CHD) and the effect of apoE on lipids and lipoproteins in healthy Chinese subjects. METHODS: Sixty-eight patients with CHD younger than 55 years (CHD1), 136 patients with CHD older than 65 years (CHD2), and 136 healthy subjects were enrolled, and their plasma levels of triglyceride (TG), total cholesterol (TC) and high density lipoprotein cholesterol (HDL-C) were determined. The apoE genotypes were identified by polymerase chain reaction-restriction fragment length polymorphism. RESULTS: apoE 3/4 genotype and E4 allele frequency in the CHD1 group were higher than those in the CHD2 group and healthy subjects, while no differences were found between CHD2 and healthy subjects. Meanwhile, the plasma levels of TC and low density lipoprotein cholesterol (LDL-C) were higher in the CHD2 group than in both CHD1 group and healthy subjects. Each apoE isoprotein has variable TC and LDL-C levels that is E2 (E2/2 + E2/3) < E3(E3/3) < E4(E4/4 + E3/4). CONCLUSION: apoE is one of the genetic factors that affect TC and LDL-C levels, and apoE 4 has a very close relation to CHD, suggesting that apoE 4 is an independent genetic factor of the early onset of CHD.

Adult↗

PubMed2001

Diagnosis and treatment of bronchial rupture from blunt thoracic trauma.

OBJECTIVE: To evaluate the diagnosis and management of bronchial rutpture from blunt thoracic trauma. METHODS: A group of 31 patients with bronchial rupture was involved. Chest roentgenography, tomography and bronchoscopy were performed on all patients. The surgical technique and complications were described. RESULTS: Diagnosis was confirmed by tomography and bronchoscopy in all the patients. End to end anastomosis was used in 26 patients. Four patients were operated with total pneumonectomy. One patient was repaired with an intercostal muscle and rib flap with blood supply. Of the 31 patients, one died of adult respiratory distress syndrome after operation. Most patients had excellent surgical outcomes. 81% (25/31) of the bronchial rupture were delayed in diagnosis and treatment. The classic symptoms and signs of bronchial rupture included subcutaneous emphysema, dyspnea and an intermediate coma interval. The roentgenogram showed mediastinal emphysema, pneumothorax, "drop lung" sign and marked radiodensity of hilum widened mediastinum. CONCLUSION: Bronchoscopy is a useful and accurate method to diagnose and treat the bronchial rupture, with which surgeons can easily locate the rupture site during surgery. Surgical treatment could restore pulmonary function in most patients.

Adolescent↗