Biomedical subjects

G Hu

Publications and source records attributed to G Hu.

At least 73 records · Page 4Linked to original sources

PubMed2001

Lack of role for nitric oxide in cholinergic modulation of myocardial contractility in vivo.

Despite intensive investigation, the role of nitric oxide (NO) in cholinergic modulation of myocardial contractility remains unresolved. The left anterior descending coronary artery of 34 anesthetized, open-chest dogs was perfused via an extracorporeal circuit. Segmental shortening (SS) was measured with ultrasonic crystals and coronary blood flow (CBF) was measured with an ultrasonic flow transducer. An intracoronary infusion of ACh (20 microg/min) was performed, with CBF held constant, under baseline and during dobutamine, CaCl(2), or amrinone at doses increasing SS by approximately 50% (10 microg/min, 15 mg/min, and 300 microg/min ic, respectively). ACh-induced responses during dobutamine were also assessed following treatment with the NO synthase inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME; 300 microg/min ic for 15 min). The effects of sodium nitroprusside (SNP; 80 microg/min ic), an exogenous NO donor, bradykinin (2.5 microg/min ic), a nonmuscarinic releaser of endothelial NO, and bilateral vagal stimulation (before and after L-NAME) were evaluated during dobutamine. ACh had no effect on SS under baseline or during CaCl(2), but it decreased SS during dobutamine or amrinone (-23 +/- 4% and -30 +/- 5%, respectively). Vagal stimulation also reduced SS during dobutamine. L-NAME did not alter the ACh- or vagal-induced decreases in SS during dobutamine. Neither SNP nor bradykinin affected SS during dobutamine. In conclusion, ACh and vagal stimulation have a negative inotropic effect during stimulation of the beta-adrenergic receptors that is independent of NO. The persistence of this effect during amrinone suggests that a mechanism downstream from adenylate cyclase is involved.

Acetylcholine↗

PubMed2001

Msx homeobox genes inhibit differentiation through upregulation of cyclin D1.

During development, patterning and morphogenesis of tissues are intimately coordinated through control of cellular proliferation and differentiation. We describe a mechanism by which vertebrate Msx homeobox genes inhibit cellular differentiation by regulation of the cell cycle. We show that misexpression of Msx1 via retroviral gene transfer inhibits differentiation of multiple mesenchymal and epithelial progenitor cell types in culture. This activity of Msx1 is associated with its ability to upregulate cyclin D1 expression and Cdk4 activity, while Msx1 has minimal effects on cellular proliferation. Transgenic mice that express Msx1 under the control of the mouse mammary tumor virus long terminal repeat (MMTV LTR) display impaired differentiation of the mammary epithelium during pregnancy, which is accompanied by elevated levels of cyclin D1 expression. We propose that Msx1 gene expression maintains cyclin D1 expression and prevents exit from the cell cycle, thereby inhibiting terminal differentiation of progenitor cells. Our model provides a framework for reconciling the mutant phenotypes of Msx and other homeobox genes with their functions as regulators of cellular proliferation and differentiation during embryogenesis.

Animals↗

PubMed2001

Helicobacter pylori detection in Chinese subjects: a comparison of two common DNA fingerprinting methods.

This study aims to demonstrate DNA diversity in Helicobacter pylori strains obtained from patients with peptic ulcer disease and compare the results from two DNA fingerprinting techniques. H. pylori strains (n = 42), collected from June 1996 to August 1999, were cultured from storage at -80 degrees C. DNA diversity was determined by the polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) analysis, and random amplified polymorphic DNA (RAPD)-PCR. Isolates showed a significant DNA sequence diversity by both methods. RAPD-PCR demonstrated 33 distinct strain-specific band patterns, whereas PCR-RFLP demonstrated six distinct restriction patterns. PCR-RFLP identified four of the 42 strains as mixed growth, compared with RAPD-PCR which did not reveal any co-colonisation. Diversity among H. pylori clinical isolates was demonstrated distinctly by both methods; however, RAPD-PCR showed greater discriminatory power in distinguishing between isolates.

Bacterial Typing Techniques↗

PubMed2001

[A prospective study on the effects of low-osmolar and nonionic contrast media on renal functions].

OBJECTIVE: To investigate the effects of contrast medium, especially large dose of Iopromide, on renal functions. METHODS: 100 hospitalized patients who were going to have cardiac or renal angiography were selected. 96 patients had normal renal functions and 4 had slightly abnormal renal functions. Scr, Ccr, urine gamma-GT and urine glucose were monitored on the first, third and fifth day after angiography. RESULTS: All the 100 patients were administered with Iopromide. Of the 96 patients with normal renal functions, all had elevated urine gamma-GT on the first day after giving Iopromide; the level returned to normal on the third day. There was no significant change of Scr and Ccr after angiography. Of the 4 patients with abnormal renal functions, all had significant change of Scr and Ccr after using Iopromide and the levels of both returned to pre-angiography level on the fifth day. CONCLUSIONS: In patients with normal renal functions, Iopromide may cause transient elevation of urine gamma-GT level and positive urine glucose. In patients with slightly abnormal renal functions, Iopromide may cause significant decrease of Ccr and increase of Scr. However, with proper treatment, these indexes may return to pre-angiography level on the fifth day after angiography.

Adolescent↗

PubMed2001

[Identification of Mortieralla isabellina M6-22 delta 6-fatty acid desaturase by heterologous expression in Saccharomyces cerevisiae].

Using plasmid pTMICL6 containing delta 6-fatty-acid desaturase gene from Mortieralla isabellina M6-22 as a template, 1.38 kb DNA fragment was amplified by PCR. The fragment was subcloned into the yeast-E. coli shuttle vector pYES2.0, then an expression recombinant plamid pYMID6 containing target gene was constructed. The pYMID6 was transformed into Saccharomyces cerevisiae for expression by LiAc method. It was found to exhibit delta 6-fatty acid desaturase activity in the recombinant S. cerevisiae YMID6 in the presence of exogenous fatty acid substrate linoleic acid under introduction of GAL. Expression of the delta 6-fatty acid desaturase gene under appropriate media and temperature conditions led to the production of gamma-linolenic acid reached 8.69% of the total yeast fatty acid by GC-MS detection. It is the first report about expression of M. isabellina D6D gene in S. cerevisiae.

Fatty Acids↗

PubMed2001

[The effect of perindopril in treatment of early diabetic nephropathy with normal blood pressure and microalbuminuria].

OBJECTIVE: To study the effect of perindopril in decreasing the urinary albumin excretion rate (AER) and protecting the renal function in normotensive early diabetic nephropathy. METHODS: 52 diabetic patients with AER between 20 to 200 microg/min, were treated with dietary regimen, oral antihyperglycemic agents or/ and insulin till their fasting blood glucose (FBG) was < 7.0 mmol/L and postprandial blood glucose (PBG) < 10.0 mmol/L. They were then divided randomly into two groups. Group A was a control group (25 cases), the patients were administered with placebo, group B was a treatment group (27 cases), the patients were administered with perindopril (4 mg/day) FBG, PBG, glycosylated haemoglobin A1c (HbA1c), AER, blood pressure (MAP) and blood creatinine (Cr) were examined immediately and 3, 6, 12 and 18 months after the treatment. RESULTS: In group A, AER was significantly increased after 12 and 18 months than at beginning, they were (52.3 +/- 8.6) microg/min and (60.4 +/- 9.0) microg/min vs (44.2 +/- 6.8) microg/min (P < 0.05). In group B, after being treated with perindopril, AER estimated 3, 6, 12 and 18 months later were (20.3 +/- 5.6) microg/min, (22.1 +/- 6.1) microg/min, (21.3 +/- 5.9) microg/min and (20.8 +/- 5.7) microg/min respectively, all were significantly lower those that of group A in the same period (P < 0.05) and also significantly lower than those at the beginning (P < 0.05). CONCLUSION: Perindopril has good effects in decreasing AER in normotensive early diabetic nephropathy and in protecting the renal function.

Adult↗

PubMed2000

The intrinsic function of a motor system--from ion channels to networks and behavior.

The forebrain, brainstem and spinal cord contribution to the control of locomotion is reviewed in this article. The lamprey is used as an experimental model since it allows a detailed cellular analysis of the neuronal network underlying locomotion. The focus is on cellular mechanisms that are important for the pattern generation, as well as different types of pre- and postsynaptic modulation. This experimental model is bridging the gap between the molecular and cellular level to the network and behavioral level.

Animals↗

PubMed2000

From low-dimensional synchronous chaos to high-dimensional desynchronous spatiotemporal chaos in coupled systems

The dynamic behavior of coupled chaotic oscillators is investigated. For small coupling, chaotic state undergoes a transition from a spatially disordered phase to an ordered phase with an orientation symmetry breaking. For large coupling, a transition from full synchronization to partial synchronization with translation symmetry breaking is observed. Two bifurcation branches, one in-phase branch starting from synchronous chaos and the other antiphase branch bifurcated from spatially random chaos, are identified by varying coupling strength epsilon. Hysteresis, bistability, and first-order transitions between these two branches are observed.

Journal Article↗

PubMed2000

Solution structure of BmP01 from the venom of scorpion Buthus martensii Karsch.

From the venom of scorpion Buthus martensii Karsch,a short peptide (BmP01, 29 amino acid residues) was isolated and characterized as previously reported (Lebren, R. R., et al. (1997) Eur. J. Biochem. 245, 457-464). It was shown to reduce 33% outward K(+) channel (hippocampal neurons) currents at 10 microM. The solution structure of BmP01 was determined by 2D (1)H NMR spectroscopy. The NOEs, coupling constants, and H-D exchange obtained from NMR spectroscopy were used in structural calculations. The conformation of BmP01 is composed of a short alpha-helix (Cys 3-Thr 12) and a two-stranded antiparallel beta-sheet (Ala 15-Asp 20 and Lys 23-Pro 28). There are three disulfide bridges (Cys 3-Cys 19, Cys 6-Cys 24 and Cys 10-Cys 26) connecting the alpha-helix and beta-sheet. Asp 20 to Lys 23 form a type II turn linking the two strands. Structural and electrostatic potential comparison between BmP01 and its analogues are also presented.

Amino Acid Sequence↗

PubMed2000

gamma-catenin is regulated by the APC tumor suppressor and its oncogenic activity is distinct from that of beta-catenin.

beta-Catenin and gamma-catenin (plakoglobin), vertebrate homologs of Drosophila armadillo, function in cell adhesion and the Wnt signaling pathway. In colon and other cancers, mutations in the APC tumor suppressor protein or beta-catenin's amino terminus stabilize beta-catenin, enhancing its ability to activate transcription of Tcf/Lef target genes. Though beta- and gamma-catenin have analogous structures and functions and like binding to APC, evidence that gamma-catenin has an important role in cancer has been lacking. We report here that APC regulates both beta- and gamma-catenin and gamma-catenin functions as an oncogene. In contrast to beta-catenin, for which only amino-terminal mutated forms transform RK3E epithelial cells, wild-type and several amino-terminal mutated forms of gamma-catenin had similar transforming activity. gamma-Catenin's transforming activity, like beta-catenin's, was dependent on Tcf/Lef function. However, in contrast to beta-catenin, gamma-catenin strongly activated c-Myc expression and c-Myc function was crucial for gamma-catenin transformation. Our findings suggest APC mutations alter regulation of both beta- and gamma-catenin, perhaps explaining why the frequency of APC mutations in colon cancer far exceeds that of beta-catenin mutations. Elevated c-Myc expression in cancers with APC defects may be due to altered regulation of both beta- and gamma-catenin. Furthermore, the data imply beta- and gamma-catenin may have distinct roles in Wnt signaling and cancer via differential effects on downstream target genes.

Adenomatous Polyposis Coli Protein↗

PubMed2000

Antioxidant nutrients and pulmonary function: the Third National Health and Nutrition Examination Survey (NHANES III).

Recent studies of chronic obstructive pulmonary disease have raised interest in its relation to nutrition. Several dietary antioxidants have been positively associated with lung function in healthy, general population samples. This study considered the separate and joint effects of vitamin C, vitamin E, beta-carotene, and selenium intake and used both dietary assessment and serum biomarkers of antioxidant status. The authors used data from the Third National Health and Nutrition Examination Survey comprising a sample representative of the US population in 1988-1994 (n = 18,162 subjects aged > or =17 years). Multiple linear regression analysis examined the separate and joint effects of the antioxidants on the ratio of forced expiratory volume in the first second (FEV1)/height2 adjusted for covariates. Each of the dietary and serum antioxidant nutrients was significantly associated with FEV1. When they were considered simultaneously (dietary and serum variables considered in separate models), independent associations were observed for most nutrients. Serum beta-carotene was less positively associated with FEV1 in smokers than nonsmokers, while serum selenium had a stronger positive association with FEV1 in smokers. The authors found that higher levels of antioxidant nutrients are associated with better lung function. The finding that the antioxidants differ in both their overall association with lung function and in whether this association varies by smoking status has implications for further research.

Adult↗

PubMed2000

Targeted disruption of NDST-1 gene leads to pulmonary hypoplasia and neonatal respiratory distress in mice.

In order to address the biological function of GlcNAc N-deacetylase/N-sulfotransferase-1 (NDST-1), we disrupted the NDST-1 gene by homologous recombination in mouse embryonic stem cells. The NDST-1 null mice developed respiratory distress and atelectasis that subsequently caused neonatal death. Morphological examination revealed type II pneumocyte immaturity, which was characterized by an increased glycogen content and a reduced number of lamellar bodies and microvilli. Biochemical analysis further indicated that both total phospholipids and disaturated phosphatidylcholine were reduced in the mutant lung. Our data revealed that NDST-1 was essential for the maturation of type II pneumocytes and its inactivation led to a neonatal respiratory distress syndrome.

Amidohydrolases↗

PubMed2000

An association study of polymorphisms in the alpha-antichymotrypsin gene for Alzheimer disease in Han-Chinese.

Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) and DNA sequencing were employed to screen the coding region of the alpha-antichymotrypsin (AACT) gene in Han-Chinese population for polymorphism possibly associated with Alzheimer's disease (AD). Consequently, seven polymorphic sites including 25A>G, 39G>A, 370C>T, 662T>G, 892C>T, 923T>C and 1332A>G were detected. Of them, the 25A>G was reported previously and the others are all novel. We subsequently focused on the 25A>G and the 39G>A polymorphism that were of interest to us and conducted an association study of them by another scanning of 246 controls that matched the AD patients. Statistic test showed that both genotype (p=0.0378, Fisher's exact, two tailed) and allele frequency (p=0.0382, Fisher's exact, two tailed) of 39G>A are different between AD patients and the controls. As for 25A>G, lain only the heterozygous genotype A/G associates with AD (p=0.0220, chi(2)), but not the A allele frequency (p=0.1141, chi(2)).

Aged↗

PubMed2000

The effect of different interventional treatment on P-Glycoprotein in different histopathological types and grades of primary hepatocellular carcinoma.

To study the effect of the different interventional treatment on P-Glycoprotein (Pgp) in different histopathological types of primary hepatocellular carcinoma (PHC), 98 surgically and histologically verified PHC specimens were obtained. The patients included 57 patients treated by surgical resection alone and 41 patients receiving second-stage surgical resection after four kinds of interventional treatment. SABC immunohistochemical staining with a monoclonal antibody against human Pgp was used to observe the Pgp in all specimens. The positive rate of Pgp was 100% in group of chemotherapy alone (P < 0.05), 62.5% in group of chemotherapy combined with iodized oil (P > 0.05), 46.6% in group of chemotherapy combined with iodized oil and spongia gelatini absorbens (Sga) (P > 0.05), 18.18% in group of chemotherapy combined with Ethanol-iodized-oil and Sga (P < 0.05) and 52.63% in group of surgical resection alone. The positive rate of Pgp varied with different histopathological types, with rate of clear cell PHC being the lowest, and that of poorly differentiated or undifferentiated PHC the highest. The positive rate of Pgp was increased as pathological grades increased. Overexpression of Pgp may be responsible for the intrinsic and acquired drug resistance of PHC. Multidrug resistance (MDR) varied with different histological types. Therapy of PHC should be tailored according to individual. Local chemotherapy combined with ethanol-iodized-oil and Sga embolization may become a new way to overcome MDR of PHC.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2000

Preliminary study of stereotactic radiotherapy for lung cancer.

From March 1997 to November 1999, 45 patients with lung cancer were treated by a stereotactic radiotherapy, with 15 cases treated by a stereotactic radiotherapy alone, and 30 cases by the external radiotherapy plus stereotactic radiotherapy. The clinical target volume was 1.89-187.26 cm3 with the median being 18.17 cm3. The doses of plan target volume (PTV) edge was 16-30 Gy/2-3 times and the doses of center was 120% to 150% of PTV edge doses. The overall response rate was 84.4% (38/45), with 11 complete response (CR) and 27 partial response (PR). This study confirmed that the stereotactic radiotherapy is a safe and effective therapy for lung cancer. For those early-stage patients who can tolerate neither operation nor even conventional radiotherapy for various reasons, it can both achieve therapeutic purpose and improve quality of life.

Adenocarcinoma↗

PubMed2000

Structural basis of mRNA cap recognition by proteins.

Crystal structures have recently become available for two proteins (VP39 and eIF4E) complexed with their cognate ligand - the mRNA cap. Despite their total structural dissimilarity, both proteins bind N7-methylguanine between two parallel aromatic sidechains. The resulting stacked arrangement governs their high specificity for the alkylated form of the nucleobase.

Alkylation↗

PubMed2000

A comparison of polymorphism in the 3'-untranslated region of the prothrombin gene between Chinese and Caucasians in Australia.

The 20210G-->A mutation in the 3'-untranslated (UT) region of the prothrombin gene is extremely rare or absent in the Chinese population (0 in 449 subjects, 140 with a history of thromboembolism). This is in contrast to the results from 302 Caucasians from Australia in our study (4.6% in 153 patients with a thromboembolic history and 1.3% in 149 patients with no history). This rarity implies that the variant of the prothrombin gene is probably not the main cause of venous thromboembolism in the Chinese population. Even among Caucasians this mutation accounts for only a minor percentage of all patients with thromboembolism. The relatively low incidence of venous thromboembolism in the Chinese population compared with Caucasians is probably as a result of the low prevalence of factor V Leiden or other environmental or genetic factors.

3' Untranslated Regions↗

PubMed2000

Direct coronary vasomotor effects of sevoflurane and desflurane in in situ canine hearts.

BACKGROUND: An extracorporeal system was used to investigate the direct coronary vasomotor effects of sevoflurane and desflurane in vivo. The role of the adenosine triphosphate-sensitive potassium channels (KATP channels) in these effects was evaluated. METHODS: Twenty-one open-chest, anesthetized (fentanyl-midazolam) dogs were studied. The left anterior descending coronary artery was perfused at controlled pressure (80 mmHg) with normal arterial blood or arterial blood equilibrated with either sevoflurane or desflurane. Series 1 (n = 16) was divided into two groups of equal size on the basis of whether sevoflurane (1.2, 2.4, and 4.8%) or desflurane (3.6, 7.2, and 14.4%) was studied. The concentrations for the anesthetics corresponded to 0.5, 1.0, and 2.0 minimum alveolar concentration (MAC), respectively. Coronary blood flow (CBF) was measured with an ultrasonic, transit-time transducer. Local coronary venous samples were obtained and used to evaluate changes in myocardial oxygen extraction (EO2). In series 2 (n = 5), changes in CBF by 1 MAC sevoflurane and desflurane were assessed before and during intracoronary infusion of the KATP channel inhibitor glibenclamide (100 microg/min). RESULTS: Intracoronary sevoflurane and desflurane caused concentration-dependent increases in CBF (and decreases in EO2) that were comparable. Glibenclamide blunted significantly the anesthetic-induced increases in CBF. CONCLUSIONS: Sevoflurane and desflurane have comparable coronary vasodilative effects in in situ canine hearts. The KATP channels play a prominent role in these effects. When compared with data obtained previously in the same model, the coronary vasodilative effects of sevoflurane and desflurane are similar to those of enflurane and halothane but considerably smaller than that of isoflurane.

ATP-Binding Cassette Transporters↗