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Biomedical subjects

W Guo

Publications and source records attributed to W Guo.

At least 199 records · Page 11Linked to original sources
PubMed1997

[Voice rehabilitation with double-valve voice prosthesis after laryngectomy].

Between March 1993 and November 1996, 97 laryngectomized patients underwent voice rehabilitation with prostheses designed by ourselves. Of these patients, 84 were males and 13 females. The age ranged from 35 to 78 years. 20 cases had the prosthesis inserted during the laryngectomy operation (first stage), while other 77 cases were inserted after the laryngectomies (second stage). The results showed that all of the patients had clear voice with their own local dialect. 34 of them could even sing songs. 68 cases had been followed-up for 2 years. All could speak during the effective time of the prosthesis and no misswallow occurred.

Adult↗
PubMed1997

Association of Helicobacter pylori infection with precancerous lesions and stomach cancer: a case-control study in Yangzhong County.

Previous study has raised H. pylori infection as a suspected biologic risk factor for gastric cancer. A comparative case-control study involving precancerous lesions and gastric cancer was conducted in Yanzhong county, an area with one of the highest rates of gastric cancer in China to study the relationship between the H. pylori infection and gastric cancer. Subjects in the study were all randomly selected participants of a screening program for gastric cancer sponsored by the Cancer Institute of CAMS in cooperation with Yangzhong county Hospital. Totally, 125 normal controls, 108 superficial gastritis, 111 atrophic gastritis and 110 gastric cancer patients were included in our study according to endoscopy and pathology result. Status of H. pylori infection was evaluated by measuring IgG antibody in plasma with ELISA assay. Our result showed Odds ratios of H. pylori infection were higher among gastritis and cancer groups, 4.5 (95% CI 2.5-7.9) for superficial gastritis, 6.3 (95% CI 3.4-12) for atrophic gastritis, 3.3 (95% CI 1.9-5.9) for gastric cancer. It was found in our study that consumption of pickled vegetables and drinking dirty water increased the relative risk of H. pylori infection for both precancerous lesions and gastric cancer and that H. pylori infection had higher risk of atrophic gastritis and gastric cancer for males and also higher risk of atrophic gastritis for olders. Our results strongly support the casual role played by H. pylori infection in the carcinogenic process of gastric mucosa.

Aged↗
PubMed1997

Modulation of potassium channels by chronic hypoxia in neonatal rat cultured ventricular myocytes.

We studied the effects of long-term exposure to hypoxia on the developmental change of transient outward current (Ito) in neonatal rat cultured ventricular myocytes. Ventricular myocytes of day-old neonatal rat hearts were cultured in normoxic condition (21%, O2) for 15 days. Some cells were cultured at lower O2 concentration of 7.5% from day 6 to day 15. During 6-15 days of cultivation in normoxic condition, a two to three fold increase (n=11-12) in Ito density was observed without changes in the kinetics of current inactivation. In the hypoxic condition during the same culture period, the developmental increment in Ito was reduced to 53% (n=8) and was characterized by slow kinetics of the inactivation process. These results suggest that the development of Ito is influenced by the oxygen concentration, and that the remarkable increase in Ito after birth may result from an elevation in blood oxygen concentration during the perinatal period.

Action Potentials↗
PubMed1997

Immunocytochemistry of Kv1.5 potassium channel protein in cultured neonatal rat ventricular myocytes.

Of the six voltage-gated potassium channel subunits detected in adult rat heart, Kv1.5 channel is abundant and its expression is depressed in hypertrophied and infarcted myocardium. The effect of nonmyocyte cells (NMCs) on cardiac Kv1.5 channel expression was studied in cultured neonatal rat ventricular cells, using immunofluorescent cytochemistry with a polyclonal antibody against rat Kv1.5 channel protein. Co-culture with NMCs induced myocyte hypertrophy, but a downregulation of Kv1.5 channel expression. Similar changes were observed when pure myocyte culture was treated with medium supernatant of pure NMC culture. These findings suggested that some soluble factors produced by cardiac NMCs play important roles in the regulation of potassium channel density during myocardial hypertrophy.

Animals↗
PubMed1997

[Experimental studies and clinical significance of p53 gene mutation in carcinomas of the nasal cavity and paranasal sinuses].

By using PCR-SSCP method, 21 specimens of nasal cavity and paranasal sinuses carcinomas which were freshly frozen and paraffin embedded were detected for the mutation of p53 gene (exon 6). The overall mutation frequency of patients was 67% (14 out of 21), which was 33% (1 out of 3), 50% (3 out of 6), 67% (4 out of 6) and 100% (6 out of 6) respectively in clinical stage I to IV, 33% (2 out of 6), 67% (4 out of 6) and 89% (8 out of 9) respectively in well, moderately and poorly differentiated carcinomas, and 100% (4 out of 4) and 59% (10 out of 17) respectively in lymph-node metastasis and non-lymphnode metastasis. It was not statistically significant when the Chi-square test was applied (P > 0.05), but there was a tendency towards an increase in p53 mutation frequency with highly malignant, poorly differentiated and lymph-node metastasis carcinomas. The results indicate that the mutation of p53 gene plays an important role in the initial and progression of nasal cavity and praranasal sinuses carcinomas. Detection of p53 mutation using the above sensitive and rapid method reveals practical significance for judging malignant level and evaluating prognosis of nasal cavity and paranasal sinuses carcinomas.

Adenocarcinoma↗
PubMed1997

[Electroencephalogram changes of meningioma].

Electroencephalogram (EEG) was used in investigating 42 cases of meningiomas proved by operations and pathological examinations. The abnormality rate of EEG was 95.24%. Compared with the clinical findings, the accuracy rate of EEG lesion-location was 64.29%; the accuracy rate of EEG lesion-side location was 26.19%; the total accuracy rate of lesion-location and lesion-side location was 90.48%. The EEG characteristics and the value of location diagnosis of meningioma were discussed. This indicates that EEG is still an important supplementary diagnostic method of intracranial meningioma.

Adolescent↗
PubMed1996

Ahch, the mouse homologue of DAX1: cloning, characterization and synteny with GyK, the glycerol kinase locus.

We cloned the murine full-length cDNA encoding Ahch, the mouse homologue of DAX1 (DSS-AHC Region on Human X Chromosome, Gene1) which is the gene responsible for human X-linked adrenal hypoplasia congenita (AHC) and hypogonadotropic hypogonadism (HH). Sequence analysis revealed that the murine and human cDNAs have 65% aa identity and 75% aa similarity overall. The cysteine residues in the putative DNA binding domain, which may interact with Zn2+ ions to form zinc fingers, are 100% conserved between the two species, indicating that the novel zinc-finger structures in DAX1 may be functional. In addition, mouse interspecific backcrosses show that the Ahch gene is closely linked to the glycerol kinase locus, GyK, on the mouse X chromosome, indicating that the order of the loci is conserved in this syntenic region between mouse and human.

Adrenal Glands↗
PubMed1996

Identification of a novel pelD gene expressed uniquely in planta by Fusarium solani f. sp. pisi (Nectria haematococca, mating type VI) and characterization of its protein product as an endo-pectate lyase.

Antibodies prepared against a pectin-inducible pectate lyase (PLA) produced by a phytopathogenic fungus Fusarium solani f. sp. pisi (Nectria haematococca, mating type VI) were previously found to protect the host from infection. The gene (pelA) and two of its homologs were cloned and sequenced. Here we report the isolation of a new pectate lyase gene, pelD, from a genomic library of F. solani pisi. A 1.5-kb DNA fragment containing pelD and its flanking regions was sequenced. The nucleotide sequence of pelD would encode a protein of 24.5 kDa which shares 49, 44, and 65% amino acid sequence identity with PLA, PLB, and PLC, respectively, from the same fungus. Because the first 19 amino acid residues appeared to be a signal peptide, the mature enzyme could be a 22.7-kDa protein. pelD transcripts and PLD protein could not be detected in fungus cultured in glucose, pectin, pea epicotyl extract, or a pea cell wall preparation. However, pelD transcripts were readily found by RT-PCR with RNA isolated from infected pea tissues. The cDNA of pelD, thus obtained, was expressed in Pichia pastoris with the putative pelD signal sequence. The secreted PLD was purified and characterized to be an endopectate lyase, and its lyase activity could be inhibited by anti-PLA IgG. Thus, protection of the host observed with the anti-PLA antibodies could reflect inhibition of immunologically related pectate lyases including PLD which is expressed uniquely in planta.

Amino Acid Sequence↗
PubMed1996

Characterization of the structure and function of a new mitogen-activated protein kinase (p38beta).

Mitogen-activated protein (MAP) kinase cascades represent one of the major signal systems used by eukaryotic cells to transduce extracellular signals into cellular responses. Four MAP kinase subgroups have been identified in humans: ERK, JNK (SAPK), ERK5 (BMK), and p38. Here we characterize a new MAP kinase, p38beta. p38beta is a 372-amino acid protein most closely related to p38. It contains a TGY dual phosphorylation site, which is required for its kinase activity. Like p38, p38beta is activated by proinflammatory cytokines and environmental stress. A comparison of events associated with the activation of p38beta and p38 revealed differences, most notably in the preferred activation of p38beta by MAP kinase kinase 6 (MKK6), whereas p38 was activated nearly equally by MKK3, MKK4, and MKK6. Moreover, in vitro and in vivo experiments showed a strong substrate preference by p38beta for activating transcription factor 2 (ATF2). Enhancement of ATF2-dependent gene expression by p38beta was approximately20-fold greater than that of p38 and other MAP kinases tested. The data reported here suggest that while closely related, p38beta and p38 may be regulated by differing mechanisms and may exert their actions on separate downstream targets.

Activating Transcription Factor 2↗
PubMed1996

Lowered risks of hypertension and cerebrovascular disease after vitamin/mineral supplementation: the Linxian Nutrition Intervention Trial.

A total of 3,318 men and women from a region in rural China were randomized to receive daily either a multiple vitamin/mineral supplement or a placebo. Deaths that occurred in the participants were ascertained and classified according to cause over the 6-year period from 1985 to 1991. At the end of supplementation, blood pressure readings were taken, and the prevalence of hypertension was determined. There was a slight reduction in overall mortality in the supplement group (relative risk (RR) = 0.93, 95 percent confidence interval (CI) 0.75-1.16), with the decreased relative risk most pronounced for cerebrovascular disease deaths (RR = 0.63, 95 percent CI 0.37-1.07). This benefit was greater for men (RR = 0.42, 95 percent CI 0.19-0.93) than for women (RR = 0.93, 95 percent CI 0.44-1.98). Among the survivors, the presence of elevations in both systolic and diastolic blood pressures was less common in those who received the supplement (RR for men = 0.43, 95% CI 0.28-0.65; RR for women = 0.92, 95 percent CI 0.68-1.24). This study indicates that supplementation with a multivitamin/mineral combination may have reduced mortality from cerebrovascular disease and the prevalence of hypertension in this rural population with a micronutrient-poor diet.

Adult↗
PubMed1996

Biochemical characterization and molecular cloning of cardiac triadin.

Triadin is an intrinsic membrane protein first identified in the skeletal muscle junctional sarcoplasmic reticulum and is considered to play an important role in excitation-contraction coupling. Using polyclonal antibodies to skeletal muscle triadin, we have identified and characterized three isoforms in rabbit cardiac muscle. The cDNAs encoding these three isoforms of triadin have been isolated by reverse transcription-polymerase chain reaction and cDNA library screening. The deduced amino acid sequences show that these proteins are identical in their N-terminal sequences, whereas the C-terminal sequences are distinct from each other and from that of skeletal muscle triadin. Based upon both the amino acid sequences and biochemical analysis, all three triadin isoforms share similar membrane topology with skeletal muscle triadin. Immunofluorescence staining of rabbit cardiac muscle with antibodies purified from the homologous region of triadin shows that cardiac triadin is primarily confined to the I-band region of cardiac myocytes, where the junctional and corbular sarcoplasmic reticulum is located. Furthermore, we demonstrate that the conserved region of the luminal domain of triadin is able to bind both the ryanodine receptor and calsequestrin in cardiac muscle. These results suggest that triadin colocalizes with and binds to the ryanodine receptor and calsequestrin and carries out a function in the lumen of the junctional sarcoplasmic reticulum that is important for both skeletal and cardiac muscle excitation-contraction coupling.

Amino Acid Sequence↗
PubMed1996

Low molecular weight rat fibroblast tropomyosin 5 (TM-5): cDNA cloning, actin-binding, localization, and coiled-coil interactions.

Previous studies have shown that three distinct genes encode six isoforms of tropomyosin (TM) in rat fibroblasts: the alpha gene encodes TM-2, TM-3, TM-5a, and TM-5b, the beta gene encodes TM-1, and the TM-4 gene encodes TM-4. Here we report the characterization of a cDNA clone encoding the most recent rat fibroblast TM to be identified, herein referred to as TM-5, that is the product of a fourth gene that is homologous to the human hTMnm gene, herein referred to as the rat slow-twitch alpha TM gene. The cDNA clone is approximately 1.7 kb and encodes a protein of 248 amino acids. Using two-dimensional gel electrophoresis, the TM-5 protein was found to co-migrate with fibroblast TM-5a and 5b. Comparison of the amino acid sequences of TM-5 to other fibroblast isoforms encoded by the alpha, beta, and TM-4 genes revealed a high degree of homology, although there were regions of divergence among the different isoforms. The gene encoding TM-5 is expressed in all tissues examined including skeletal muscle, stomach, heart, liver, kidney, uterus, spleen, brain, and diaphragm. However, Northern blot and RNase protection analyses revealed the presence of different mRNAs in fibroblasts, striated muscle (skeletal and diaphragm), and brain, which are expressed via alternative RNA splicing and the use of alternative promoters. The TM-5 protein was expressed in a bacterial system and tested for its ability to bind actin in vitro and in vivo. The apparent TM association constant (Ka) was taken as the free concentration at half saturation and was found to be 3 microM for TM-5 compared to 2 microM for TM-5b at an F-actin concentration of 42 microM. When fluorescently-labeled TM-5 was microinjected into living rat fibroblasts, it localized to the stress fibers and ruffles of the leading lamella. The coiled-coil interactions of TM-5 with other low and high molecular weight TM isoforms were studied. TM-5 and TM-4 were capable of dimerizing with each other as well as with other low molecular weight isoforms (TM-5a and TM-5b), but not with the HMW isoforms (TM-1, TM-2, and TM-3). In addition, TM-5a and TM-5b were unable to heterodimerize with each other. The implications of these results in understanding the role of TM diversity in cytoskeletal dynamics are discussed.

Actins↗
PubMed1996

No continuous relationship between Veterans Affairs hospital coronary artery bypass grafting surgical volume and operative mortality.

BACKGROUND: The purpose of this study was to determine whether risk-adjusted coronary artery bypass grafting mortality rates are significantly related to coronary artery bypass grafting surgical procedure volume within the Department of Veterans Affairs hospital system. METHODS: From April 1987 to September 1992, expected mortality rates were calculated for 23,986 coronary artery bypass grafting procedures performed at 44 different Veterans Affairs hospitals. RESULTS: This study found a statistically significant relationship between annual hospital coronary artery bypass grafting volume and observed mortality rates (p < 0.02). However, no statistically significant relationship between coronary artery bypass grafting volume and risk-adjusted operative mortality was found (p = 0.10). Using analysis of variance on hospital-level data, hospitals with 100 or less cases per year have higher observed to expected mortality ratios than hospitals performing more than 100 cases per year (p = 0.03). Using Poisson regression models, however, a volume threshold could not be found. CONCLUSIONS: These findings are consistent with the current Veterans Affairs policy requirements to periodically review quality at low-volume hospitals.

Analysis of Variance↗
PubMed1996

Additive effects of glyburide and antidepressants in the forced swimming test: evidence for the involvement of potassium channel blockade.

Evidence in the literature suggests that the modulatory effects of antidepressant drugs (ADS) on neuronal excitability, via the inhibition of K+ channels, may be the final common pathway of pharmacological action. Therefore, we tested the hypothesis that combining the ATP-sensitive K+ channel blocker glyburide with a variety of ADS would produce an additive effect and decrease the immobility time of mice in the forced swimming test (FST). Glyburide (GLY, IP, 30 and 50 mg/kg) and subactive doses of ADS were administered 45 and 30 min, respectively, prior to behavioral testing. Results showed that when combined with GLY, ADS whose main pharmacological effect is one of 5-HT uptake blockade (imipramine, amitriptyline, citalopram, paroxetine, fluoxetine, and fluvoxamine) were more effective in decreasing the amount of time mice were immobile, than when these drugs were administered alone. Some noradrenaline uptake inhibiting ADS (desipramine and viloxazine, but not maprotiline) were also significantly more effective in decreasing immobility time when combined with GLY than when administered alone. Pretreatment with GLY was found to have no effect on the dopamine uptake inhibitor bupropion, and out of the atypical ADS tested (trazodone, mianserine and iprindole), only coadministration with iprindole decreased the immobility time. Only the specific MAO-A inhibitor moclobemide was observed to have an antiimmobility effect when combined with GLY. Neither MAO-B specific (RO 16 6491) nor mixed MAO inhibitors (nialamide and pargyline) interacted with GLY to produce antiimmobility effects. These results corroborate and extend our previous report of the ADS enhancing effects of quinine in the same behavioral model, and suggest that the additive effects of quinine and GLY on ADS in FST are a result of K+ channel blockade.

Animals↗
PubMed1996

13C MAS NMR studies of crystalline cholesterol and lipid mixtures modeling atherosclerotic plaques.

Cholesterol and cholesteryl esters are the predominant lipids of atherosclerotic plaques. To provide fundamental data for the quantitative study of plaque lipids in situ, crystalline cholesterol (CHOL) and CHOL/cholesteryl ester (CE) mixtures with other lipids were studied by solid-state nuclear magnetic resonance with magic-angle-sample spinning. Highly distinctive spectra for three different crystalline structures of CHOL were obtained. When CHOL crystals were mixed with isotropic CE oil, solubilized CHOL (approximately 13 mol % CHOL) was detected by characteristic resonances such as C5, C6, and C3; the excess crystalline CHOL (either anhydrous or monohydrate) remained in its original crystalline structure, without being affected by the coexisting CE. By use of 13C-enriched CHOL, the solubility of CHOL in the CE liquid-crystalline phase (approximately 8 mol %) was measured. When phosphatidylcholine was hydrated in presence of CHOL and CE, magic-angle-sampling nuclear magnetic resonance revealed liquid-crystalline CHOL/phosphatidylcholine multilayers with approximately an equal molar ratio of CHOL/phosphatidylcholine. Excess CHOL existed in the monohydrate crystalline form, and CE in separate oil or crystalline phases, depending on the temperature. The magic-angle-sampling nuclear magnetic resonance protocol for identifying different lipid phases was applied to intact (ex vivo) atherosclerotic plaques of cholesterol-fed rabbits. Liquid, liquid-crystalline, and solid phases of CE were characterized.

Animals↗
PubMed1996

Delayed effects of epidermal growth factor after extensive small bowel resection.

Epidermal growth factor (EGF) is produced in the gastrointestinal tract and has been shown to have a transient stimulatory effect on mucosal growth and uptake of glutamine. This study investigated the delayed effects of EGF on mucosal brush-border membrane enzymes and glutamine uptake after extensive small bowel resection. Twenty-four New Zealand White rabbits underwent a 50% to 60% midjejunoileal enterectomy. One group of 12 had a subcutaneous osmotic pump inserted, delivering EGF at 0.3 microgram/kg/h for the first 7 postoperative days. The other group of 12 served as controls. Six rabbits from each group were killed at 3 weeks, and the remaining 12 were killed at 6 weeks. Six additional rabbits served asd nonsurgical controls. There was a twofold increase in mucosal dry weight at 3 weeks without EGF, and an almost fourfold increase with EGF, over control rabbits. This effect of EGF on the mucosa persisted for 6 weeks. Enzymatic activity per gram of protein in each group of rabbits was similar between the four groups of rabbits, although maltase activity increased approximately fourfold over that of nonoperative control animals. However, enzyme capacity of maltase and aminooligopeptidase (AOP) increased threefold and twofold (respectively) at 3 weeks without EGF, and sixfold and fourfold with EGF. Functional capacity is a measure of the load of nutrients that the intestine can digest and absorb, and therefore the derivable benefit to the animal. Glutamine uptake capacity increased 60% in 3 weeks without EGF, then declined by 6 weeks. However with EGF it increased 200% by 3 weeks, and further increased 400% by 6 weeks over control levels. The authors conclude that EGF markedly increases the functional capacity of the small intestine in rabbits that have undergone extensive small bowel resection; this effect persists for up to 6 weeks after a small initial dosage of EGF.

Animals↗
PubMed1996

AP1 enhances polyomavirus DNA replication by promoting T-antigen-mediated unwinding of DNA.

An early step in the initiation of polyomavirus DNA replication is viral large-T-antigen-mediated unwinding of the origin. We report that components of the AP1 transcription factor, Fos and Jun, interact with T antigen in vitro to enhance unwinding of the viral origin. This provides a biochemical basis for the capacity of AP1 to activate viral DNA replication in vivo.

Antigens, Viral, Tumor↗