Biomedical subjects

J Yuan

Publications and source records attributed to J Yuan.

At least 199 records · Page 11Linked to original sources

PubMed1998

[Analysis of essential oils in prepared Chinese Angelica].

OBJECTIVE: Through chemical analysis of the essential oils obtained from prepared Chinese study Angelica to provide a scientific evidence for compatibility study of Siwu decoction. METHOD: Capillary GC-MS. RESULTS: In the essential oils of the head of Angelica 88 peaks have been detected and 42 of them (51.34% of the oils) have been identified; while in those of the whole Angelica 94 peaks have been detected and 54 of them (90.86% of the oils) have been identified. CONCLUSION: Constituents in the essential oils obtained from prepared Chinese Angelica have been identified for the first time.

Angelica↗

PubMed1998

[Chemical constituents of Quercus mongolica Fisch].

OBJECTIVE: To study the chemical constituents of the leaves of Quercus mongolica. METHOD: Using techniques of silical gel column chromatography and HNMR, 13CNMR. RESULT: Four compounds were isolated and identified as friedelin, glutinol, lupeo and beta-sitosterol respectively. CONCLUSION: All the compounds were isolated from this plant for the first time.

Drugs, Chinese Herbal↗

PubMed1998

[Isolation and cloning of expressed sequences in a region flanking ANK1 on human chromosome 8p11.2].

OBJECTIVE: Our efforts were to isolate expressed sequences in a region flanking ANK1 on chromosome 8p11.2. METHODS: cDNA selection method was applied to isolate the expressed sequences from yeast artificial chromosomes(YAC) mapped to the region flanking ANK1 and one of the expressed sequences was isolated for the screening for human fetal brain cDNA library. RESULTS: Seven cDNA sequences were identified. Of these sequences, five were mapped back to their corresponding YAC. The remaining two sequences (BHLC26 and BHLC181) did not hybridize to any YAC used. BHLC152 was highly homologous to a gene for the musculus CArG box-binding factor. BHLC74 shared substantial identity with the gene encoding ventricular myosin alkali light chain 1 (MLC1), indicating that it might encode a MLC1 isoform. Partial sequence from other expressed sequences bore homology with some expressed sequences tagged with unknown function and without mapped data in the databases. BHLC119 was used as probe to screen cDNA libraries. One positive clone was sequenced. Its insert is 1,951 bp in length and encode a predicted 174 amino acids without homology with known proteins. One transcript of 3.5 kb was detected in total RNA from human fetal brain by Northern blotting. Tissue expression analysis suggests that it is a widely-expressed gene. CONCLUSION: BHLC74 may be considered a candidate gene for the 8p-related heart diseases. Other expressed sequences isolated might be used at least as candidates screening preliminarily for the tumor suppressor gene mapped to the region flanking ANK1 on 8p11.2.

Amino Acid Sequence↗

PubMed1998

[The role of nitric oxide in hyperdynamic circulation in portal hypertensive rats].

OBJECTIVE: To evaluate the role of nitric oxide (NO) in hyper-hemodynamics in portal hypertension, we investigated the effects of nitric oxide synthase inhibitor L-NMMA with or without L-arginine, the substrate for enzyme NO synthase on the systemic and splanchnic hemodynamics in portal hypertensive rats. METHOD: Ninety-seven male Sprague-Dawley rats were divided into four groups: intrahepatic portal hypertension (IHPH, n = 23) by injection of CCl4, prehepatic portal hypertension (PHPH, n = 26) by stenosis of the portal vein, end-to-side portacaval shunt (PCS, n = 23), and sham-operated controls (SO, n = 25). Animals of each group were divided into three subgroups: systemic administration of L-NMMA (50 mg/kg BW, 1 ml), L-NMMA (50 mg/kg BW, 0.5 ml) plus L-arginine (30 mg/kg BW, 0.5 ml), and normal saline solution (1 ml). The radioactive microsphere method was used for hemodynamic study. RESULT: There was the characteristic of hyperdynamic circulatory state including increased cardiac output and splanchnic blood flow, decreased mean arterial blood pressure, total peripheral vascular resistance and splanchnic vascular resistance in IHPH, PHPH and PCS rats. The hyperdynamic circulatory state in IHPH, PHPH and PCS rats could be effectively reversed by L-NMMA to the resting values of hemodynamics in SO rats, but not the levels after administration of L-NMMA in SO rats, indicating that there is excessive production of NO in portal hypertensive and PCS rats. Administration of L-arginine counterbalanced the effects of L-NMMA on hyperdynamic circulatory state in portal hypertensive and PCS rats. CONCLUSION: NO is an important mediator of hyperdynamic circulation in portal hypertension.

Animals↗

PubMed1998

[A clinical observation of the therapeutic effects of pilocarpine gel for treatment of glaucoma].

OBJECTIVE: To evaluate whether pilocarpine gel (PG) is better than pilocarpine solution (PS) for treatment of glaucoma. METHODS: 20 cases with glaucoma treated with 4% PG once every night were compared with 20 cases with glaucoma using 1% PS 4 times a day. The intraocular pressure (IOP), pupil diameter and refraction were examined 4 times a day in both groups. RESULTS: The PG could lower IOP by 25% - 37% and the PS by 20% - 25%, the hypotensive effect of PG could last 24 hours. The PG had the strongest hypotensive effect 5 - 13 hours after its application, and a stronger action than PS at 9 a.m. and 11 a.m, this is particularly beneficial for the control of the peak IOP before awaking and in the morning. The strongest action of miosis and accommodation enhancement of PG took place 5 - 8 hours after its application when the patients were sleeping, whereas the PS induced a fluctuating miosis and myopia in the day time. In addition, the PG was more convenient to be used than PS due to its single application for 24 hours. CONCLUSION: The PG has some advantages in the respects of compliance, lowering IOP and side-effects, thus it is worthwhile to promote its manufacture.

Adult↗

PubMed1998

[The experimental study on competitive PCR for quantitation of herpesviruses].

A single pair of oligonucleotide primer selected within a highly conserved region of the DNA polymerase gene in herpesviruses was synthesized. The competitive template DNA purified from cytomegalovirus (CMV) DNA was used to carry out competitive PCR amplification with herpes simplex virus type 1 (HSV1) DNA (target sequences). And anti-HSV1 effects of acyclovir (ACV) was investigated by the method. The results showed that the efficacy of PCR amplification was equal to each other(the ratio of the quantity of competitor template with DNA to the target sequence was 1.5:1). As the concentration of ACV was increased, the quantity of HSV1, DNA was decreased. It suggests that this method is practicable and some defects of mutant template can be overcomed.

Acyclovir↗

PubMed1998

[Spectroscopic characteristics of Ce3+ doped Ca3Al2M3O12 (M=Si, Ge) garnets].

The spectral properties of Ce3+ doped Ca3Al2M3O12 (M = Si, Ge) garnets have been reported under excitation of UV light. The emission spectra of Ce3+ ion in garnets consist of a broad band assingning to the 5d-4f transition of Ce3+ ion. The emission intensity Ce3+ ion in Ga3Al2Ce3O12 shows very weak, but in Ga3Al2SiO12 shows strong. The emission intensity of Ce3+ ion is greatly enhanced by adding Gd3+ or flux into Ca3Al2Si3O12: Ce garnet. At 295 and 77K, the fluorescence decay of Ce3+ ions in Ca3Al2Si3O12 garnet have been measured and the fluorescence lifetimes of Ce3+ ions are 46 and 49ns, respectively.

English Abstract↗

PubMed1998

[Spectral study of the conformational change of yeast alcohol dehydrogenase induced by alcohol].

The conformational change of Yeast Alcohol Dehydrogenase (YADH) at the different concentration of ethanol, n-propanol and ethylene glycol was studied by means of ultraviolet spectrum, fluorescence spectrum and circular dichroism spectrum. The results showed that the ultraviolet absorbance at 220nm and 280nm as well as the relative fluorescence intensity at 336nm of YADH increased with increasing alcohol concentration. The negative peakes at 208nm and 220nm of YADH in circular dichroism spectrum with the solvent of ethanol, ethylene glycol were obviously intensified, but the 220nm peak of YADH was increased in the presence of n-propanol while the 208nm peak was decreased and red-shifted in position as to completely lost. According to the data above, it indicates that the conformation of YADH was changed with losing activity at the various concentration of alcohol.

Alcohol Dehydrogenase↗

PubMed1997

Highly sensitive time-resolved fluoroimmunoassay of human immunoglobulin E by using a new europium fluorescent chelate as a label.

A new europium fluorescent chelate, 4,4'-bis(1",1",1",2",2",3",3"-heptafluoro-4",6"-hexanedione-6"-yl) - chlorosulfo-o-terphenyl (BHHCT)-Eu3+, was used as a label for highly sensitive time-resolved fluoroimmunoassay of human IgE. Two assay formats were employed in the analysis. In the first format, an immunoconjugate of rabbit anti-human IgE antibody-human IgE-biotinylated goat anti-human IgE antibody-BHHCT-Eu(3+)-labeled SA (or BHHCT-Eu(3+)-labeled BSA-SA; BSA, bovine serum albumin; SA, streptavidin) was used for measurement. The method gives the detection limits of 3.6 x 10(-2) IU/ml (labeled SA) and 1.1 x 10(-2) IU/ml (labeled SA-BSA). In the second format, an immunoconjugate of goat anti-human IgE antibody-human IgE-rabbit anti-human IgE antibody-biotinylated goat anti-rabbit IgG antibody-BHHCT-Eu(3+)-labeled SA (or BHHCT-Eu(3+)-labeled BSA-SA) was used for measurement. The detection limits of these methods are 3.0 x 10(-3) IU/ml (labeled SA) and 1.5 x 10(-3) IU/ml (labeled BSA-SA). The above detection limits are one to two orders of magnitude lower than those of the conventional radioimmunoassay and enzyme immunoassay. The CV of the present method is less than 7%, and the recovery is in the range of 85-105% for serum samples.

Animals↗

PubMed1997

A novel receptor for Apo2L/TRAIL contains a truncated death domain.

Apo2 ligand (Apo2L [1], also called TRAIL for tumor necrosis factor (TNF)-related apoptosis-inducing ligand [2]) belongs to the TNF family and activates apoptosis in tumor cells. Three closely related receptors bind Apo2L: DR4 and DR5, which contain cytoplasmic death domains and signal apoptosis, and DcR1, a decoy receptor that lacks a cytoplasmic tail and inhibits Apo2L function [3-5]. By cross-hybridization with DcR1, we have identified a fourth Apo2L receptor, which contains a cytoplasmic region with a truncated death domain. We subsequently named this protein decoy receptor 2 (DcR2). The DcR2 gene mapped to human chromosome 8p21, as did the genes encoding DR4, DR5 and DcR1. A single DcR2 mRNA transcript showed a unique expression pattern in human tissues and was particularly abundant in fetal liver and adult testis. Upon overexpression, DcR2 did not activate apoptosis or nuclear factor-kappaB; however, it substantially reduced cellular sensitivity to Apo2L-induced apoptosis. These results suggest that DcR2 functions as an inhibitory Apo2L receptor.

Adult↗

PubMed1997

Specific proteolysis of the kinase protein kinase C-related kinase 2 by caspase-3 during apoptosis. Identification by a novel, small pool expression cloning strategy.

The caspase family of proteases plays a critical role in the execution of apoptosis. However, efforts to decipher the molecular mechanisms by which caspases induce cell death have been greatly hindered by the lack of systematic and broadly applicable strategies to identify their substrates. Here we describe a novel expression cloning strategy to rapidly isolate cDNAs encoding caspase substrates that are cleaved during apoptosis. Small cDNA pools (approximately 100 clones each) are transcribed/translated in vitro in the presence of [35S]methionine; these labeled protein pools are then incubated with cytosolic extracts from control and apoptotic cells. cDNA pools encoding proteins that are specifically cleaved by the apoptotic extract and whose cleavage is prevented by the caspase inhibitor acetyl-Tyr-Val-Ala-Asp chloromethylketone are subdivided and retested until a single cDNA is isolated. Using this approach, we isolated a partial cDNA encoding protein kinase C-related kinase 2 (PRK2), a serine-threonine kinase, and demonstrate that full-length human PRK2 is proteolyzed by caspase-3 at Asp117 and Asp700 in vitro. In addition, PRK2 is cleaved rapidly during Fas- and staurosporine-induced apoptosis in vivo by caspase-3 or a closely related caspase. Both of the major apoptotic cleavage sites of PRK2 in vivo lie within its regulatory domain, suggesting that its activity may be deregulated by proteolysis.

Amino Acid Chloromethyl Ketones↗

PubMed1997

Naturally occurring A pocket polymorphism in HLA-B*2703 increases the dependence on an accessory anchor residue at P1 for optimal binding of nonamer peptides.

Previous studies have shown the B*2703 subtype of HLA-B27, which differs from B*2705 and other MHC class I molecules by having a His substituted for Tyr at position 59 in the A pocket, inefficiently presents certain B*2705-restricted peptides. The current work investigates the influence of the first peptidic amino acid (P1) on peptide binding to B*2705 and B*2703. Results show P1 has a marked effect for both subtypes, with relative affinities (EC50) of P1-substituted peptides spanning four orders of magnitude. All peptides tested bind better to B*2705 than to B*2703. However, Lys, Arg, Phe, or Trp at P1 result in a < or = 2-fold difference between subtypes, while other amino acids produce greater differences (maximum approximately 50-fold for Leu). Self peptides eluted from B*2703, as well as two viral epitopes, have a motif similar to B*2705 peptides, except for a stronger preference for Lys or Arg at P1, consistent with peptide binding data. Computer modeling of B*2703 reveals movement of a water molecule and the alpha1 alpha-helix to allow His at position 59 to maintain important hydrogen bonds with the peptide N terminus in the A pocket. However, these bonds are weaker, and the water molecule movement results in the loss of a hydrogen bond with Glu-45 in the B pocket. We conclude that B*2703, as a consequence of its unique A pocket polymorphism, appears to have a greater dependency on an accessory anchor residue at P1 to maintain tight binding of peptides.

Alleles↗

PubMed1997

N-methylation dissociates methamphetamine's neurotoxic and behavioral pharmacologic effects.

The present studies further examined the effect of N-methylation on the behavioral and neurotoxic effects of methamphetamine. Drug discrimination studies employing a training dose of 1 mg/kg of methamphetamine were used to confirm and extend previous behavioral studies indicating that N-methylation reduced the behavioral activity of methamphetamine 5- to 10-fold. In subsequent neurotoxicity studies, rats received doses of methamphetamine (10 mg/kg, s.c., every 6 h x 5) or its N-methylated derivative, N,N-dimethylamphetamine (100 mg/kg, s.c., every 6 h x 5) that, based on the results of the behavioral studies, would be expected to produce behaviorally equivalent effects. Saline-treated rats served as controls. Two weeks after treatment, the status of brain dopamine (DA) and serotonin (5-HT) neurons was assessed by measuring DA and 5-HT axon terminal markers. As anticipated, methamphetamine produced neurochemical deficits indicative of DA and 5-HT axon terminal damage. By contrast, despite the fact that it was given at a dose behaviorally equivalent to methamphetamine, N-N-dimethylamphetamine failed to produce signs of DA or 5-HT neurotoxicity. These results indicate that N-methylation dissociates methamphetamine's neurotoxic and behavioral pharmacologic effects, and suggest that it may be possible to separate the neurotoxic and pharmacologic effects of other substituted amphetamine derivatives with potentially useful clinical activity (e.g. fenfluramine and methylenedioxymethamphetamine).

3,4-Dihydroxyphenylacetic Acid↗

PubMed1997

Need for caspases in apoptosis of trophic factor-deprived PC12 cells.

PC12 cells are a useful model system for studying neuronal apoptosis. Like neurons, they undergo apoptosis when deprived of trophic support. Involvement of caspases [interleukin 1beta-converting enzyme (ICE)-related proteases] has been implicated in apoptosis induced by various stimuli in many cell types, including neurons. In the present study we investigated the need for caspases participation in apoptosis induced by growth factor deprivation in naive and neuronal PC12 cells. For this purpose we generated PC12 cell lines that consistently express the viral caspases inhibitor genes p35 or crmA, and analyzed their susceptibility to trophic factor deprivation. We also examined the effects of cell-permeable peptide inhibitors of caspases. Our results showed that broad-spectrum inhibitors of the caspases, namely the baculovirus p35 gene and the peptide benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone, effectively inhibit the death of both naive and neuronal PC12 cells. However, caspase-1 (ICE)-specific inhibitors, namely the peptides Ac-Try-Val-Ala-Asp-chloromethylketone and Ac-Try-Val-Ala-Asp-aldehyde, as well as crmA, were much less effective. These findings demonstrate that caspases, but not caspase-1, are needed for apoptosis induced by trophic factor deprivation in both naive and neuronal PC12 cells. Northern and Western blot analyses showed that PC12 cells express caspase-3. We therefore examined the involvement of caspase-3 in the death process of trophic factor-deprived PC12 cells. Our results showed that the pro-caspase-3 and its substrate poly-(ADP-ribose) polymerase are cleaved at similar rates in serum-deprived PC12 cells. Moreover, cell lysates prepared from these cells possess caspase-3-like activity, as determined by their ability to cleave the fluorogenic peptide substrate Ac-Asp-Glu-Val-Asp-7-amino-4-methylcoumarin. These findings strongly suggest that caspase-3 or caspase-3-like proteases are activated in trophic factor-deprived PC12 cells.

Amino Acid Chloromethyl Ketones↗

PubMed1997

Molecular Transport and SAPO-11 Crystal Growth in an i-Pr2NH-AlPO4-H3PO4-SiO2-H2O System

The crystal growth of SAPO-11 molecular sieve synthesized with i-Pr2NH as a novel template from mixtures of Si, Al, and P sources were studied by XRD, MAS-NMR, IR, and AAS techniques. It was found that the crystallization was improved partially by the desorption of i-Pr2NH from the crystallite products at high temperatures. The growth on (010) face was enhanced by stepwise adding external silica sol to the reaction mixtures during the synthesis process. The molecular transport and mechanism of the crystallization were discussed. Copyright 1997 Academic Press. Copyright 1997Academic Press

Journal Article↗

PubMed1997

Methylphenidate and brain dopamine neurotoxicity.

To further evaluate the dopamine (DA) neurotoxic potential of the widely prescribed psychostimulant, methylphenidate, mice were treated with various doses (range: 10-120 mg/kg) and treatment schedules of methylphenidate (every 2 h x 4 or twice daily x 4). Higher doses of methylphenidate produced intense stereotypy, as well as short- (5-day), but not long- (2-week), term depletions of striatal DA axonal markers. By contrast, amphetamine caused not only intense stereotypy, but also profound, long-lasting, dose-related DA deficits. These findings indicate that results of studies of amphetamine neurotoxicity using short (5-day) post-drug survival periods are potentially misleading. Further, the present findings confirm and extend previous results indicating that methylphenidate, unlike amphetamine, lacks DA neurotoxic potential, and strongly suggest that DA efflux, although perhaps necessary, is not sufficient for the expression of amphetamine-induced DA neurotoxicity.

3,4-Dihydroxyphenylacetic Acid↗

PubMed1997

Activation of caspase-2 in apoptosis.

Members of the CED-3/interleukin-1beta-converting enzyme (ICE) protease (caspase) family are synthesized as proforms, which are proteolytically cleaved and activated during apoptosis. We report here that caspase-2 (ICH-1/NEDD-2), a member of the ICE family, is activated during apoptosis by another ICE member, a caspase-3 (CPP32)-like protease(s). When cells are induced to undergo apoptosis, endogenous caspase-2 is first cleaved into three fragments of 32-33 kDa and 14 kDa, which are then further processed into 18- and 12-kDa active subunits. Up to 50 microM N-acetyl-Asp-Glu-Val-Asp-aldehyde (DEVD-CHO), a caspase-3-preferred peptide inhibitor, inhibits caspase-2 activation and DNA fragmentation in vivo, but does not prevent loss of mitochondrial function, while higher concentrations of DEVD-CHO (>50 microM) inhibit both. In comparison, although the activity of caspase-3 is very sensitive to the inhibition of DEVD-CHO (<50 nM), inhibition of caspase-3 activation as marked by processing of the proform requires more than 100 microM DEVD-CHO. Our results suggest that the first cleavage of caspase-2 is accomplished by a caspase-3-like activity, and other ICE-like proteases less sensitive to DEVD-CHO may be responsible for activation of caspase-3 and loss of mitochondrial function.

Apoptosis↗

PubMed1997

Insulin-like growth factor-I receptor overexpression mediates cellular radioresistance and local breast cancer recurrence after lumpectomy and radiation.

The insulin-like growth factor-I receptor (IGF-IR) plays a critical role in cell growth regulation and transformation. The radiosensitivity of NIH 3T3 fibroblasts overexpressing either wild-type or mutant IGF-IR was examined. High levels of wild-type IGF-IR conferred radioresistance, and mutational analysis revealed that this effect correlated with the transforming capacity but not the mitogenic activity of the receptor. The radioresistant phenotype was reversed when the cells were incubated with antisense oligonucleotides targeted to IGF-IR mRNA, demonstrating that IGF-IR directly influences radioresistance. The clinical significance of these findings was examined in an immunohistochemical analysis of primary breast tumors, revealing that high levels of IGF-IR in tumor samples were highly correlated with ipsilateral breast tumor recurrence (IBTR) following lumpectomy and radiation therapy (P = 0.001). Subgroup analysis revealed that, for early breast tumor relapses (within 4 years of initial breast tumor diagnosis), elevated levels of IGF-IR were strongly associated with IBTR (P = 0.004) but IGF-IR expression was not prognostic for IBTR from breast cancer patients with late relapses (P was not significant). These studies provide evidence for the influence of IGF-IR on cellular radioresistance and response to therapy and raise the possibility that the radiocurability of selected tumors may be improved by pharmaceutical strategies directed toward the IGF-IR.

3T3 Cells↗