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Biomedical subjects

X Hu

Publications and source records attributed to X Hu.

At least 109 records · Page 6Linked to original sources
PubMed2001

[Investigation on root-knot diseases of medicinal plants in Yunnan].

During 1994-1997, the damage levels about root-knot diseases on 52 medicinal plants were investigated and analyzed. 185 samples were collected from more than 20 counties or cities in Yunnan province. The results showed that 76 specimens were infected by root-knot nematode, which are Meloidogyne incognita (Kofoid and White 1919, Chitwood 1949), M. javanice (Trenb 1855, Chitwood 1949), M. arenaria (Neal 1889, Chitwood 1949) and M. halpa (Chitwood 1949). They infected 21 medicinal plants. The paper describes the damage levels and the distribution about these root-knot diseases of medicinal plants.

Animals↗
PubMed2001

[Effects of change of crown contour on health of gingiva].

OBJECTIVE: To study the effects of different excessive crown contours on the health of periodontium. METHODS: A total of 63 posterior teeth of 12 volunteers were randomly divided into three groups and each group was consisted of 21 teeth. The buccal surfaces of the teeth were overcontoured 0.2 mm, 0.5 mm, and 0.8 mm respectively. At the point of 1 week, 4 weeks and 8 weeks, gingival cervical fluid (GCF) were collected, GCF-aspartate aminotransferase (GCF-AST) and GCF-alkaline phosphatase (GCF-ALP) levels were tested and the debris amount was assessed for three groups. RESULTS: The 0.8 mm group presented most amount of GCF, highest level of GCF-AST, GCF-ALP and most debris. The 0.5 mm group was the second. When the excess was 0.2 mm, all indexes showed no statistically significant change. CONCLUSIONS: Excessive crown contour is unfavourable to periodontium health. The more the teeth are excessively contoured, the more they impair periodontium.

Adult↗
PubMed2001

[Effect of xanthnotoxol on contractility of isolated rabbit ileum].

OBJECTIVE: To study the effect of Xanthnotoxol on contractility of isolated rabbit ileum and its relationship with Ca2+. METHOD: Routine experimental methods for isolated ileum were adopted. RESULT: Xanthnotoxol (XT) and Verapamil (Ver) inhibited the contraction of isolated rabbit ileum smooth muscle induced by submaximal concentrations of acetylcholine (ACh) and serotonim (5-TH), with a IC50 value (mumol.L-1) of 10.495 +/- 1.521, 0.428 +/- 0.001 and 18.132 +/- 1.627, 0.249 +/- 0.003, respectively. XT and Ver inhibited the contraction induced by Ca2+ after high K+ depolarization and for noncompetitively antagonist CaCl2 cumulative dose-response curve, the pD'2 value was 4.69 +/- 0.03 and 6.35 +/- 0.10, respectively. XT (10 mumol.L-1) and Ver(0.06 mumol.L-1) inhibited the contraction induced by ACh in Ca(2+)-free medium, while XT (100 mumol.L-1) but not Ver(0.6 mumol.L-1) inhibited the extracellar CA(2+)-dependent contraction induced by ACh. CONCLUSION: XT has a calcium-antagonistic effect which was not similar to that of Ver.

Animals↗
PubMed2001

[Study on third-type immunoliposomes loaded drugs and the targeting in vitro and in vivo].

AIM: To study the preparation, targeting and pharmacodynamics of third-type immunoliposome loaded anticancer drugs. METHODS: The monoclonal antibody of human bladder cancer was combined with the terminal of PEG-COOH (polyethyleneglycol carboxylic acid) that make the liposomes not only prolong circulation by the membrane protection of PEG, but also target by spreading the antibody on the liposomes surface. That was the third type immunoliposomes. According to this scheme, the IML-ADM (immunoliposome carried adriamycin) wes prepared in which ADM entrapment was efficient and stability was high and the antibody activity was kept. RESULTS: The % survival of the targeting EJ cells treated with IML-ADM (ADM = 45.45 micrograms.mL-1) was 4.3% +/- 1.0%, but 72% +/- 6% for non-targeting LOVO cells in vitro; the tumor weight in nude mice which were implanted by EJ cells after 27 days were (39 +/- 25) mg, (135 +/- 32) mg, (598 +/- 240) mg treated by IML-ADM, SSL-ADM (steric stable lipsomes carried Adriamycin) and normal saline, respectively, in vivo. CONCLUSION: The results confirmed that the immunoliposme-mediated targeting anticancer drug is a feasible way.

Animals↗
PubMed2001

[Study on DNA oxidative damage of O3 aging model in mice].

OBJECTIVE: This study was aimed to detect the animals' DNA oxidative damage. METHODS: A free radical mouse aging model was established by putting the mouse in a device for inhaling quantities of ozone (O3). Single cell gel electrophoresis (SCGE) was used for assessing the splenolymphocytes' DNA damage. RESULTS: The appearance rate of comet and the length grade of DNA migration for the young control group (P < 0.05). No significant difference in the degree of DNA damage was observed between the O3 model group and the natural aging group(P > 0.05). CONCLUSION: The DNA damage of O3 animal model is consistent with that of natural aging animal; this animal model DNA damage of O3 animal model is consistent with that of natural aging animal; this animal model and the method of SCGE are useful for future researches on aging and antiaging medicine.

Aging↗
PubMed2001

[Maxillofacial vascular malformation associated with abnormal communication between external carotid and cranial arteries].

OBJECTIVE: To introduce the clinical characteristics of maxillofacial vascular malformation with abnormal communication between external carotid and cranial arteries. METHODS: One hundred and twenty patients with maxillofacial vascular malformations had been studied by arteriography of internal and external carotid, and vertebral arteries before embolization of tumor supplying artery. Cases found to have communications between extra- and intra-cranial arteries were analyzed. RESULTS: Fourteen patients (11.67%, 14/120) were found to have abnormal communications between external carotid and cranial arteries. Among them, 11 patients demonstrated communications between occipital and vertebral arteries, 1 patient showed ascending pharyngeal artery and vertebral artery communication, and 2 patients showed maxillary artery-ophthalmic artery communication. CONCLUSION: Embolization of tumor supplying artery is a safe and practical method for the treatment of maxillofacial vascular malformation when done under digital subtraction angiography and superselective catheterization to avoid the abnormal communicant branches.

Adolescent↗
PubMed2000

Receptor-interacting protein 140 directly recruits histone deacetylases for gene silencing.

Receptor-interacting protein 140 (RIP140) encodes a histone deacetylase (HDAC) inhibitor-sensitive repressive activity. Direct interaction of RIP140 with HDAC1 and HDAC3 occurs in vitro and in vivo as demonstrated in co-immunoprecipitation and glutathione S-transferase pull-down experiments. The HDAC-interacting domain of RIP140 is mapped to its N-terminal domain, between amino acids 78 and 303 based upon glutathione S-transferase pull-down experiments. In chromatin immunoprecipitation assays, it is demonstrated that histone deacetylation occurs at the chromatin region of the Gal4 binding sites as a result of Gal4 DNA binding domain-tethered RIP expression. The immunocomplexes of RIP140 from cells transfected with RIP140 and HDAC are able to deacetylate histone proteins in vitro. This study presents the first evidence for RIP140 as a negative coregulator for nuclear receptor actions by directly recruiting histone deacetylases and categorizes RIP140 as a novel negative coregulator that is able to directly interact with HDACs.

Adaptor Proteins, Signal Transducing↗
PubMed2000

Location of the epoxide function determines specificity of the allelic variants of human glutathione transferase Pi toward benzo[c]chrysene diol epoxide isomers.

Carcinogenic activity of many polycyclic aromatic hydrocarbons (PAHs) is mainly attributed to their respective diol epoxides, which can be classified as either bay or fjord region depending upon the location of the epoxide function. The Pi class human glutathione (GSH) transferase (hGSTP1-1), which is polymorphic in humans with respect to amino acid residues in positions 104 (isoleucine or valine) and/or 113 (alanine or valine), plays an important role in the detoxification of PAH-diol epoxides. Here, we report that the location of the epoxide function determines specificity of allelic variants of hGSTP1-1 toward racemic anti-diol epoxide isomers of benzo[c]chrysene (B[c]C). The catalytic efficiency (k(cat)/K(m)) of V104,A113 (VA) and V104,V113 (VV) variants of hGSTP1-1 was approximately 2.3- and 1.7-fold higher, respectively, than that of the I104,A113 (IA) isoform toward bay region isomer (+/-)-anti-B[c]C-1,2-diol-3,4-epoxide. On the other hand, the IA variant was approximately 1.6- and 3.5-fold more efficient than VA and VV isoforms, respectively, in catalyzing the GSH conjugation of fjord region isomer (+/-)-anti-B[c]C-9,10-diol-11,12-epoxide. The results of the present study clearly indicate that the location of the epoxide function determines specificity of the allelic variants of hGSTP1-1 in the GSH conjugation of activated diol epoxide isomers of B[c]C.

Alleles↗
PubMed2000

Cofactor dynamics and sufficiency in estrogen receptor-regulated transcription.

Many cofactors bind the hormone-activated estrogen receptor (ER), yet the specific regulators of endogenous ER-mediated gene transcription are unknown. Using chromatin immunoprecipitation (ChIP), we find that ER and a number of coactivators rapidly associate with estrogen responsive promoters following estrogen treatment in a cyclic fashion that is not predicted by current models of hormone activation. Cycles of ER complex assembly are followed by transcription. In contrast, the anti-estrogen tamoxifen (TAM) recruits corepressors but not coactivators. Using a genetic approach, we show that recruitment of the p160 class of coactivators is sufficient for gene activation and for the growth stimulatory actions of estrogen in breast cancer supporting a model in which ER cofactors play unique roles in estrogen signaling.

Breast Neoplasms↗
PubMed2000

An intronic Ikaros-binding element mediates retinoic acid suppression of the kappa opioid receptor gene, accompanied by histone deacetylation on the promoters.

The mouse kappa opioid receptor (KOR) gene is constitutively expressed in mouse embryonal carcinoma P19 stem cells and suppressed by retinoic acid (RA) in cells undergoing neuronal differentiation. A negative regulatory element is located within intron 1 of the KOR gene, which contains an Ikaros (Ik)-binding site (GGGAAgGGGAT). This sequence is an Ik-1 respondive, functionally negative element as demonstrated in the context of both natural KOR and heterologous promoters. The two underlined G residues of the second half-site are critical for Ik-1 binding and Ik-mediated repression of the KOR gene. RA induces Ik-1 expression within 1 day of treatment and suppresses KOR expression between 2 and 3 days. Overexpression of Ik-1 in P19 suppresses endogenous KOR gene expression, accompanied by increased binding of Ik-1 to the Ik-binding site and chromatin histone deacetylation on KOR promoters. It is proposed that in an RA-induced P19 differentiation model, RA elevates Ik-1 expression, which recruits histone deacetylase to intron 1 of the KOR gene and silences KOR gene promoters.

Acetylation↗
PubMed2000

Association analysis of polymorphisms in the DRD4 gene and heroin abuse in Chinese subjects.

Heroin abuse is a major social and public health problem in many parts of the world, yet relatively little is known about its etiology. Although genes play a role in determining susceptibility, they are expected to be of small effect with considerable heterogeneity. Because the dopamine system is involved in reward, its neurotransmitter receptors are candidates for etiological involvement in addiction. In the present study, we examine two polymorphisms in the dopamine D4 receptor, a VNTR in exon III and a point mutation in the promoter (-512C/T) that affects transcriptional efficiency. We examined a sample of 405 heroin-abusing subjects and 304 controls from Sichuan Province, Southwest China. One hundred twenty-one of these cases and 154 controls were previously used in a study of the DRD4 VNTR [Li et al., 1997], and the remainder are newly ascertained. The two polymorphisms were in weak but detectable linkage disequilibrium (1, 418 chromosomes, P < 0.00001, D' = 0.17). When we compared the heroin-abuse group with controls, we found no significant difference between the patients and controls for either polymorphism in the DRD4 gene or their haplotypes. We were also unable to replicate our earlier association between "long" DRD4 alleles and heroin abuse. However, division of the sample by route of administration (nasal inhalers or injectors) produced a significant difference between inhalers and controls for the DRD4 VNTR (six-fold corrected P = 0. 018 by allele) but not for injectors of heroin. The association we observed between inhalers and the DRD4 polymorphism is difficult to interpret, although it is possible that the association is explained by different levels of novelty seeking between the two subgroups.

Administration, Inhalation↗
PubMed2000

Transforming growth factor beta inhibits the phosphorylation of pRB at multiple serine/threonine sites and differentially regulates the formation of pRB family-E2F complexes in human myeloid leukemia cells.

Transforming growth factor beta (TGFbeta)1 induced dephosphorylation of pRb at multiple serine and threonine residues including Ser249/Thr252, Thr373, Ser780, and Ser807/811 in MV4-11 cells. Likewise, TGFbeta1 caused the dephosphorylation of p130, while inhibiting accumulation of p107 protein. Phosphorylated pRb was detected to bind E2F-1 and E2F-3, which appears to be a major form of pRb complexes in actively cycling cells. TGFbeta1 significantly downregulated pRb-E2F-1 and pRb-E2F-3 complexes as a result of inhibition of E2F-1 and E2F-3. In contrast, complexes of E2F-4 with pRb and with p130 were increased markedly upon TGFbeta1 treatment, whereas p107 associated E2F-4 was dramatically decreased. In agreement with these results, p130-E2F-4 DNA binding activity was dominant in TGFbeta1 treated cells, whereas p107-E2F-4 DNA binding activity was only found in proliferating cells. Our data strongly suggest that inhibition of E2Fs and differential regulation of pRb family-E2F-4 complexes are linked to TGFbeta1-induced growth inhibition. E2F-4 is switched from p107 to p130 and pRb when cells are arrested in G1 phase by TGFbeta1.

Blotting, Western↗
PubMed2000

Possible tricritical point in phase diagrams of interlayer josephson-vortex systems in high- T(c) superconductors

A critical value in the product of the anisotropy parameter and the magnetic field is observed in interlayer Josephson-vortex systems by extensive Monte Carlo simulations. Below (above) this critical value the thermodynamic phase transition between the normal and the superconducting states upon temperature sweeping is first (second) order. It is discussed that the origin of this tricritical point is the highly anisotropic layered structure of high- T(c) superconductors.

Journal Article↗
PubMed2000

Automated solid-phase synthesis and photophysical properties of oligodeoxynucleotides labeled at 5'-aminothymidine with Ru(bpy)2(4-m-4'-cam-bpy)2+.

A facile and automated procedure for the incorporation of a derivatized Ru(bpy)3(2+) in an oligodeoxynucleotide is reported. The Ru(bpy)3(2+)-thymidine phosphoramidite is synthesized, and then incorporated in DNA using a standard protocol on an automated DNA solid-phase synthesizer. The structure of the DNA duplex is not altered after labeling with Ru(bpy)3(2+). Photophysical studies of the novel ruthenium trisdiimine thymidine complex as well as the corresponding labeled oligodeoxynucleotides demonstrate that the favorable properties associated with the ruthenium complex are retained after covalent attachment to the nucleoside and oligodeoxynucleotide.

DNA↗
PubMed2000

Catalytic efficiencies of allelic variants of human glutathione S-transferase Pi in the glutathione conjugation of alpha, beta-unsaturated aldehydes.

The catalytic efficiencies of the allelic variants of human glutathione (GSH) S-transferase Pi (hGSTP1-1), which differ in their primary structures by the amino acids in positions 104 (isoleucine or valine) and/or 113 (alanine or valine), in the GSH conjugation (detoxification) of acrolein and crotonaldehyde have been determined. The k(cat)/K(m) values for hGSTP1-1 isoforms I104,A113 (IA), I104, V113 (IV), V104,A113 (VA) and V104,V113 (VV) toward acrolein were 129+/-3, 116+/-3, 128+/-4 and 92+/-3 mM(-1) s(-1), respectively. The catalytic efficiencies of the hGSTP1-1 variants IA, IV, and VA in the GSH conjugation of acrolein were statistically significantly higher (at P=0.05) compared with the VV isoform. On the other hand, the catalytic efficiencies of the hGSTP1-1 isoforms IA, IV, VA and VV toward crotonaldehyde (16+/-2, 12+/-1, 17+/-2, and 12+/-2 mM(-1)s(-1), respectively) were not statistically significantly different from each other. Our results suggest that hGSTP1-1 polymorphism may be an important factor in differential susceptibility of individuals to the toxic effects of acrolein, which is a widely spread environmental pollutant and generated endogenously during metabolic activation of anticancer drug cyclophosphamide.

Acrolein↗