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Biomedical subjects

G Hu

Publications and source records attributed to G Hu.

At least 127 records · Page 7Linked to original sources
PubMed1998

[Percutaneous transfemoral arterial implantation of drug delivery system for arterial infusion therapy of advanced primary hepatic carcinoma].

OBJECTIVE: To study the efficiency of arterial infusion chemotherapy via drug delivery system (DDS) for advanced primary hepatic carcinoma. METHODS: Hepatic arterial infusion chemotherapy was performed in 82 cases of primary hepatic carcinoma with no indication for operation or transarterial embolism treatment. The patients were divided into 2 group as follows: (1) Group A: 42 patients were treated intra-arterially once every 1 or 2 weeks via implanted DDS. (2) Group B: 40 patients were treated through one bolus arterial infusion chemotherapy, once every month. RESULTS: The response rate (CR + PR) was 38.1% and 15.0% respectively in group A and B (P < 0.05); the 0.5-, 1- and 2- year survival rate was 61.9%, 28.6% and 9.5% respectively in group A, but 20%, 5%, 0% respectively in group B (P < 0.01); Liver, biliary, gastrointestinal and bone marrow toxicity in group A patients was greatly lower than those in group B patients. CONCLUSION: Intermittent arterial infusion chemotherapy via DDS significantly improves survival and quality of life in patients with advanced primary hepatic carcinoma.

Adult↗
PubMed1998

[HBV markers in severe hepatitis B].

In order to elucidate the relationship between hepatitis B virus (HBV) replication and severity of hepatitis B, HBV serological markers and HBV-DNA in 56 patients with chronic hepatitis B were detected using the methods of ELISA and PCR, respectively. The results showed that the positive prevalence of HBeAg and/or HBV-DNA in chronic severe hepatitis B (5/25) was much lower than that in non-severe chronic hepatitis B (26/31) (P < 0.01). The study provides the suggestive evidence that viral replication is significantly reduced in severe hepatitis B. Also, increased replication of HBV appears to be not the cause of hepatic necrosis in severe hepatitis B.

Adult↗
PubMed1998

[A prospective investigation on interferon treatment of chronic hepatitis B].

Mismatched polymerase chain reaction and restriction fragment length polymorphism assay together with neutralization bioassay were performed in order to elucidate the influence of pre core mutation of HBV genome and neutralizing anti-INF on the therapeutic efficacy of IFN-2b. In 29 patients treated with IFN alpha-2b, HBV DNA pre core mutation were detected in 15 patients (15/29, 51.7%), HBV DNA in 7 of these 15 patients (7/15, 46.6%) turned to negative, all of whom were recurrent one year follow up. In the other 14 patients without pre core mutation, 7 patients (7/14, 50%) became serum HBV DNA negative, none of whom were recurrent. HBV DNA was undetectable in 4 of the 15 patients (4/15, 26.7%) with neutralizing antibody. In contrast, HBV DNA became undetectable in 10 of the 12 patients (10/12, 83.3%) without neutralizing antibody (P < 0.05).

Adult↗
PubMed1998

[The determination of melatonin in health-caring medicine for specific purposes by high performance liquid chromatography-mass spectrometry].

A rapid and precise method for the determination of melatonin in health-caring medicine for specific purposes, based on high performance liquid chromatography-mass spectrometry, has been developed. The compound was identified using DAD UV spectrum and mass spectrum. Hypersil ODS column, 100 mm x 2.1 mm i.d., and mobile phase of methanol-water (70:30, V/V) were used for the assays. The quantitation was performed with external standard, and detection at 275 nm. The calibration curve of melatonin was linear in the range of 5-50 mg/L and the detection limit was ca. 0.2 ng.

Chromatography, High Pressure Liquid↗
PubMed1998

[Serologic testing of hepatitis C virus infection].

We tested anti-HCV, anti-HCV IgM and HCV-RNA in serum samples from general adults, blood donors, acute hepatitis patients and liver cirrhosis patients by the methods of ELISA and RT-PCR so as to study the relationship among serum markers. Results showed that the detected positive rates of anti-HCV are 3.57%, 8.58%, 6.25% and 48.38% in normal adults, blood donors, acute hepatitis patients and liver cirrhosis patients respectively; agreement rates between anti-HCV and HCV RNA are 11.43%, 61.11%, 80.0%, and 73.33% in the four groups of people above; agreement rates between anti-HCV IgM and HCV RNA are 75.0%, 90.9% 81.81% and 100% in the same groups of people. Authors pointed out that anti-HCV IgM is superior to anti-HCV in the aspect of revealing HCV viremia. In comparison with RT-PCR, testing anti-HCV IgM is easier and does not need special instruments, so it is suitable to develop in the basic hygiene units. Testing anti-HCV IgM instead of anti-HCV, the morbidity of post-transfusion hepatitis C can be decreased further.

Antibodies, Viral↗
PubMed1998

[The measurement of baroreflex sensitivity in stress-induced hypertensive rats by spectral analysis].

Simultaneous spectral analysis of short-term systolic blood pressure variability (SBPV) and heart rate variability (HRV) was applied to determine the change of baroreflex sensitivity (BRS) in Sprague-Dawley (SD) rats. The modulus of the transfer function between fluctuations in systolic pressure and beat-to-beat interval would be an appropriate quantification of BRS. The animal experiment was performed on two groups of rats: normotensive rats and stress-induced hypertensive rats (SIHR). V1-receptor antagonist d(CH2)5Tye(Me) AVP of arginine vasopressin (AVP) was microinjected into intracerebroventricle. The results showed that, in base-line condition before administration, although the BRS in very low frequency band (0-0.035 Cycle/Beat, VLF), low frequency band (0.035-0.12 Cycle/Beat, LF), high frequency band (0.12-0.32 Cycle/Beat, HF) and total BRS(the sum of the three bands) were all decreased, the BRS in VLF(P < 0.05) and LF(P < 0.01) decreased significantly by statistics; and that, to the SIHR, the BRS in VLF was significantly lower after AVP-V1 administration than in base-line condition, while to normotensive rats, the BRS did not change. It indicates that the facilitating effect of AVP on the beroreflex in SIHR is mainly due to V1-receptor in central nerve system. In summary, the transfer function between SBPV and beat-to-beat interval fluctuation could be an index of BRS. This method can be developed for future clinical application.

Animals↗
PubMed1997

Characterization of human homologs of the Drosophila seven in absentia (sina) gene.

Studies of Drosophila photoreceptor development have illustrated the means by which signal transduction events regulate cell fate decisions in a multicellular organization. Development of the R7 photoreceptor is best understood, and its formation is dependent on the seven in absentia (sina) gene. We have characterized two highly conserved human homologs of sina, termed SIAH1 and SIAH2. SIAH1 maps to chromosome 16q12 and encodes a 282-amino-acid protein with 76% amino acid identity to the Drosophila SINA protein. SIAH2 maps to chromosome 3q25 and encodes a 324-amino-acid protein that shares 68% identity with Drosophila SINA and 77% identity with human SIAH1. SIAH1 and SIAH2 were expressed in many normal and neoplastic tissues, and only subtle differences in their expression were noted. However, one of three murine homologs, Siah1B, was strongly induced in fibroblasts undergoing apoptotic cell death. While a previous study suggested that SINA was a nuclear protein, epitope-tagged SINA and SIAH1 proteins were found in the cytoplasm of Drosophila and mammalian cells. Their substantial evolutionary conservation, role in specifying cell fate, and activation in apoptotic cells suggest the SIAH proteins have important roles in vertebrate development. Furthermore, given the role of sina in Drosophila photoreceptor development, SIAH2 is a candidate for the Usher syndrome type 3 gene at chromosome 3q21-q25.

Adult↗
PubMed1997

Mammalian homologs of seven in absentia regulate DCC via the ubiquitin-proteasome pathway.

DCC (deleted in colorectal cancer) is postulated to function as transmembrane receptor for the axon and cell guidance factor netrin-1. We report here that the DCC cytoplasmic domain binds to proteins encoded by mammalian homologs of the Drosophila seven in absentia (sina) gene, as well as Drosophila Sina. Sina has a critical role in R7 photoreceptor development and shows upward of 85% amino acid identity with its mammalian homologs (termed Siahs), but the function of the Sina/Siah proteins has not been defined. We sought, therefore, to characterize further their interaction with DCC. Immunofluorescence studies suggested the Sina/Siah proteins localized predominantly in the cytoplasm and in association with DCC. DCC was found to be ubiquitinated and the Sina/Siah proteins regulated its expression. Proteasome inhibitors blocked the effects of Sina/Siah on DCC, and the Sina/Siah proteins interacted with ubiquitin-conjugating enzymes (Ubcs). A mutant Siah protein lacking the amino-terminal Ubc-binding sequences complexed with DCC, but did not degrade it. The in vivo interaction between Sina/Siah and DCC was confirmed through studies of transgenic Drosophila lines in which DCC and Sina were ectopically expressed in the eye. Taken together, the data imply that the Sina/Siah proteins regulate DCC and perhaps other proteins via the ubiquitin-proteasome pathway.

Animals↗
PubMed1997

Nuclear translocation of human angiogenin in cultured human umbilical artery endothelial cells is microtubule and lysosome independent.

Exogenous angiogenin undergoes rapid nuclear translocation in cultured human umbilical artery endothelial cells at 37 degrees C but not at 4 degrees C. Treatment of cells with colchicine, nocodazole and taxol, which disrupt the microtubule system, does not affect the nuclear translocation process of angiogenin, suggesting that cells transport internalized angiogenin in a microtubule independent fashion. Lysosomal inhibitors, chloroquine and leupeptin, neither inhibit nor enhance the nuclear translocation of angiogenin, indicating that lysosomal targeting and processing are not required for, and do not compete with, the nuclear translocation. Moreover, treatment of cells with a tyrosine kinase antagonist, genistein, does not change the ability of the cells to translocate angiogenin into the nucleus. We suggest that exogenous angiogenin is translocated to the nucleus by a mechanism that does not require activation of tyrosine kinase, but includes receptor-mediated endocytosis, microtubule and lysosome independent transport across the cytoplasm, and nuclear localization sequence-assisted nuclear import.

Biological Transport↗
PubMed1997

Expression of epidermal growth factor receptor and human papillomavirus E6/E7 proteins in cervical carcinoma cells.

BACKGROUND: Epidermal growth factor receptor (EGF-R) proteins are highly expressed in many tumors, including those of the cervix. We have observed previously that the introduction of a transcription unit containing an antisense sequence for the E6/E7 genes of human papillomavirus (HPV) 18, along with a transcription unit containing a sense complementary DNA sequence for the wild-type retinoblastoma (Rb) gene, decreased the growth of human cervical carcinoma HeLa cells (HPV 18 positive) both in vitro and in vivo. To clarify the regulatory mechanisms by which this reduction in cell proliferation occurred, we studied the expression of EGF-R proteins in these cells. METHODS: Western blot and northern blot techniques were used to measure EGF-R expression, and a pulse-chase immunoprecipitation assay was used to measure the stability of EGF-R protein in HeLa cells and HeLa cells that had been transfected with the antisense E6/E7 or sense Rb sequences. Cell proliferation was measured by use of a tetrazolium-based colorimetric assay for numbers of viable cells. RESULTS: The introduction of sense Rb or antisense E6/E7 transcription units or a combination of these two transcription units into HeLa cells dramatically decreased the level of EGF-R proteins in these cells; EGF-R levels were not affected at the transcriptional level but at the post-transcriptional level. Addition of the anti-EGF-R-specific monoclonal antibody 225mAb to HeLa cells caused 53% (95% confidence interval = 44%-62%) growth inhibition. CONCLUSIONS: These results suggest that HeLa cervical carcinoma cells are dependent on EGF-R for proliferation and that changes in functional levels of the E6/E7 HPV proteins and endogenous Rb proteins may alter the growth rate of cervical cancer cell lines by reducing the stability of EGF-R at the post-transcriptional level.

Blotting, Northern↗
PubMed1997

Evaluation of mitral valve prolapse by four-dimensional echocardiography.

To observe the stereoscopic structure and the motion of the prolapsing mitral valve and its regurgitant jet in comparison with the normal mitral valve, four-dimensional (or dynamic three-dimensional) echocardiography of mitral valve apparatus was obtained in 20 patients with mitral valve prolapse and 10 unaffected subjects by use of transthoracic and transesophageal methods. The normal mitral valve apparatus has a consistent saddle-shaped configuration, with its anterior and posterior high points located near the aortic root and posterior left ventricular wall, respectively, and its low points located medially and laterally. In mitral valve prolapse, the spatial relation of mitral leaflets and anulus can be observed in four dimensions either from the left ventricle toward the left atrium or from the left atrium toward the left ventricle; the position, size, shape, motion, and extent of functional abnormality of the prolapsing mitral valve were clearly displayed. On the long-axis view of the left ventricle and the apical four-chamber view of four-dimensional echocardiography, the part of prolapsing mitral valve that protruded into the left atrium appeared as a spoon-like depression. We also obtained four-dimensional images of regurgitant blood flow to observe the stereoscopic view of blood flow column and its cross-sectional area, spatial position, and dynamic changes. This technique is of great value in evaluating patients with mitral valve prolapse, increasing the diagnostic sensitivity and specificity, and giving assistance to the surgeons in making preoperative therapeutic decisions and assessing the intraoperative and postoperative results.

Adult↗
PubMed1997

Heterodimerization of Msx and Dlx homeoproteins results in functional antagonism.

Protein-protein interactions are known to be essential for specifying the transcriptional activities of homeoproteins. Here we show that representative members of the Msx and Dlx homeoprotein families form homo- and heterodimeric complexes. We demonstrate that dimerization by Msx and Dlx proteins is mediated through their homeodomains and that the residues required for this interaction correspond to those necessary for DNA binding. Unlike most other known examples of homeoprotein interactions, association of Msx and Dlx proteins does not promote cooperative DNA binding; instead, dimerization and DNA binding are mutually exclusive activities. In particular, we show that Msx and Dlx proteins interact independently and noncooperatively with homeodomain DNA binding sites and that dimerization is specifically blocked by the presence of such DNA sites. We further demonstrate that the transcriptional properties of Msx and Dlx proteins display reciprocal inhibition. Specifically, Msx proteins act as transcriptional repressors and Dlx proteins act as activators, while in combination, Msx and Dlx proteins counteract each other's transcriptional activities. Finally, we show that the expression patterns of representative Msx and Dlx genes (Msx1, Msx2, Dlx2, and Dlx5) overlap in mouse embryogenesis during limb bud and craniofacial development, consistent with the potential for their protein products to interact in vivo. Based on these observations, we propose that functional antagonism through heterodimer formation provides a mechanism for regulating the transcriptional actions of Msx and Dlx homeoproteins in vivo.

Amino Acid Sequence↗
PubMed1997

Thermo Sequenase DNA polymerase and T. acidophilum pyrophosphatase: new thermostable enzymes for DNA sequencing.

A combination of thermostable enzymes has been developed that produces higher quality cycle sequences. Thermo Sequenase DNA polymerase is a thermostable enzyme engineered to catalyze the incorporation of ddNTPs with an efficiency several thousandfold better than other thermostable DNA polymerases. Since the enzyme also catalyzes pyrophosphorolysis at dideoxy termini, a thermostable inorganic pyrophosphatase is needed to remove the pyrophosphate produced during sequencing reactions. Thermoplasma acidophilum inorganic pyrophosphatase (TAP) is thermostable and effective for converting pyrophosphate to orthophosphate. The use of the combination of Thermo Sequenase polymerase and TAP for cycle sequencing yields sequence data with uniform band intensities, allowing the determination of longer, more accurate sequence reads. Uniform band intensities also facilitate interpretation of sequence anomalies and the presence of mixed templates. Sequencing PCR products of DNA amplified from heterozygous diploid individuals results in signals of equal intensity from each allele.

Cloning, Molecular↗
PubMed1997

(-)-Stepholidine enhances K+ depolarization-induced activation of synaptosomal tyrosine 3-monooxygenase from rat striatum.

AIM: To study the mechanism of K+ depolarization-induced activation of synaptosomal tyrosine 3-monooxygenase (TM) in rat striatum and the effect of (-)-stepholidine (SPD) on this activation. METHODS: The TM was assayed for DOPA by HPLC-ECD; the activities of Ca2+/calmodulin (CaM)-dependent protein kinase (PK II) and Ca2+/phosphoinositide-dependent protein kinase (PKC) were assayed using histidine as substrate. RESULTS: The incubation of striatal synaptosomes in K(+)-riched (60 mmol.L-1) medium resulted in a marked activation of TM. PKC inhibitor polymyxin B (PMB) completely blocked the activation of K+ 60 mmol.L-1 on TM. Selective D2 receptor agonist quinpirole (QP), Ca2+ removal from incubation medium and CaM antagonist W7 failed to affect the activation. However, SPD enhanced the activation of K+ 60 mmol.L-1 on TM. Meanwhile, the incubation in K+ 60 mmol.L-1 also activated PKC. Neither QP nor SPD affected K+ depolarization-induced activation of PKC. CONCLUSION: The activation of K+ depolarization on synaptosomal TM is enhanced by SPD and this activation is mediated by PKC rather than by PK II.

Animals↗
PubMed1997

[A comparative study of skeletal cephalometric of normal occlusion between the middle-old-aged and young people].

In this study the skeletal cephalometric data of normal occlusion between 39 middle-old-aged people and 30 young people were compared. The results indicated: the growth and reconstruction of the skeletal tissues of skull and jaws and face could still maintain for a period of time after grown-up. It mainly showed that skeletal tissues increased in vertical direction, the declination of occlusion plane became flat along with the increasing of ages.

Adult↗
PubMed1997

[Differential regulation of dopamine receptors on pre- and postsynaptic Na+, K(+)-ATPase in rat striatum].

The pre- and postsynaptic membranes isolated from rat striatum were used to investigate the regulation of dopamine receptors on striatal Na+, K(+)-ATPase in these membranes. The activity of Na+, K(+)-ATPase was determined by colorimetric method. Dopamine (DA) was found to inhibit the Na+, K(+)-ATPase activity on postsynaptic membranes in a concentration-dependent manner with a IC50 value of 4.6 mumol.L-1. This inhibitory effect was reversed by either selective D1 receptor antagonist SCH23390 or selective D2 receptor antagonist spipernone. The inhibitory effect similar to DA was produced by combination with selective D1 receptor agonist SKF38393 and selective D2 receptor agonist LY171555. In contrast, under the same experimental conditions, DA (10(-8)-10(-5) mol.L-1) was shown to activate the activity of Na+, K(+)-ATPase on presynaptic membranes in a concentration-dependent manner. Meanwhile, the stimulatory effect was reversed by spiperone alone rather than by SCH23390. These results show the differential regulation of presytnaptic and postsynaptic DA receptors on Na+, K(+)-ATPase in rat striatum.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1997

[Determination of minor flavor components in Chinese spirits by direct-injection technique with capillary columns].

Chinese spirits are among the best-known distilled alcoholic beverages in the world. Because of the longer multiple-strain fermentation, Chinese spirits are richer than yeast fermented western liquors in fragrance and mellow. The complex nature of Chinese spirits often makes it difficult to separate, identify and quantify major and minor flavor components. Among the several analytical methods for flavor components in Chinese spirits developed in recent years, the direct-injection technique using capillary columns is by far the best. In this study of direct injection with crosslinked PEG 20M, HP-INNOWax and bonded SGE BP21 columns, up to 68 flavor components including alcohols, organic acids, esters, acetals, carbonyl and heterocyclic compounds were identified with fine-tuning separation and followed by GC/MS to identify. The gas chromatographic separation of flavour components of Maotai Liquor by the method on PEG 20M, SGE BP21 and HP-INNOWax are shown. The compounds of the numbered peaks in the chromatograms are listed. Three compounds of, ie., amyl acetate, t-pentanol and 2-ethyl butyric acid, were used as internal standards to minimize discrimination in quantitative determination. The operation procedures for these tests were provided. The application identities of three capillary columns for the analysis of minor flavor components with direct injection were summarized respectively.

Flavoring Agents↗