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Biomedical subjects

Y F Wang

Publications and source records attributed to Y F Wang.

At least 55 records · Page 3Linked to original sources
PubMed2000

Use of rat liver slices for the study of oxidative DNA damage in comparison with isolated rat liver nuclei and HepG2 human hepatoma cells.

Tissue slices are a useful biological system for lipid peroxidation studies but their use for DNA damage studies is not well characterized. Hence, the present study investigates DNA damage in rat liver slices, in comparison with isolated rat liver nuclei and HepG2 human hepatoma cells, incubated with ferric nitrilotriacetate (Fe(III)-NTA), bromotrichloromethane (BrCCl(3)), bromobenzene (BrB) or 2-nitropropane (2-NP) at 37 degrees C for 2 hr. DNA damage was measured in slices, cells or nuclei after centrifugation as formation of as 8-hydroxy-2'-deoxyguanosine (8-OH-dGu) and loss of double-stranded (dsDNA) due to strand breakage using a fluorometric analysis of DNA unwinding (FADU). Lipid peroxidation was measured as thiobarbituric acid-reactive substances (TBARS) released into the medium. The results show that in liver slices and isolated nuclei, Fe/NTA (1 mM/4 mM) induced high levels of TBARS but low levels of 8-OH-dGu, whereas the oxidant induced low levels of TBARS and no formation of 8-OH-dGu in HepG2 cells. In all three systems, inclusion of ascorbate caused dose-dependent formation of 8-OH-dGu, and the levels were similar between liver slices and HepG2 cells but were far higher in isolated nuclei. In liver slices the FADU assay was not applicable due to limited solubilization of DNA from the slice, whereas the assay detected significant loss of dsDNA in HepG2 cells and slight loss in isolated nuclei induced by Fe/NTA with or without ascorbate. Liver slices incubated with 1 mm BrCCl(3), BrB or 2-NP had elevated TBARS but had little or no formation of 8-OH-dGu; none of these oxidants induced lipid peroxidation or DNA damage in HepG2 cells. When liver slices obtained from rats injected with diethylmaleate (to deplete GSH) were incubated with BrCCl(3), BrB or 2-NP, levels of TBARS and 8-OH-dGu increased markedly. Similarly, HepG2 cells with decreased GSH showed marked elevation of TBARS and loss of dsDNA induced by these oxidants, although no formation of 8-OH-dGu was detected. The present study demonstrates the usefulness and limitations of liver slices for DNA damage studies and the importance of cellular GSH in the protection of DNA against environmental toxicants.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2000

Male reproductive health research needs and research agenda: Asian and Pacific perspective.

Enhancing male reproductive health, and increasing men's participation in it, involves encouraging a range of positive reproductive health and social behaviour by men to help ensure women's and children's well-being. More intellectual work-including research programmes-is urgently needed to clarify the conceptual framework for male reproductive health. At the Asia and the Pacific Symposium 'Intra-regional Cooperation in Reproductive Health Research' (Shanghai, China, 12-13 October 1998) the Symposium participants identified regional research needs and recommended a regional reproductive health research agenda, which addresses six key issues related to male reproductive health: (i) male contraceptive technology; (ii) reproductive tract infections/sexually transmitted diseases and male infertility; (iii) male involvement in reproductive health; (iv) male adolescent reproductive health; (v) male reproductive ageing; and (vi) environment and male reproductive health. One of the major challenges now facing us is the elaboration of a comprehensive, yet realistic, male reproductive health research agenda that reflects the needs and demands of Asian developing countries. Making full use of an interdisciplinary approach is of strategic importance to achieve this.

Adolescent↗
PubMed2000

Arginosuccinate synthetase, arginosuccinate lyase and NOS in canine gastrointestinal tract: immunocytochemical studies.

Nitric oxide synthase (NOS) requires the substrate L-arginine for NO production to support multiple gastrointestinal functions. We asked, 'Where do enzymes to regenerate L-arginine from L-citrulline exist?'. We examined loci of immunoreactivities in the canine gastrointestinal tract for arginosuccinate synthetase and arginosuccinate lyase, enzymes that resynthesize L-arginine from L-citrulline, in relation to the distribution of nNOS immunoreactivity or NADPH-diaphorase histochemistry. Arginosuccinate synthetase and lyase were present in many neurones and nerve fibres in the myenteric plexus of the lower oesophageal sphincter (LOS), antrum, pylorus, ileum and colon; in the submucosal plexus of ileum and colon; in longitudinal muscle of ileum and colon; and in nerve bundles in circular muscle everywhere. LOS muscle was also immunoreactive for both enzymes. Circular and longitudinal muscle cells of the ileum and colon and cells resembling interstitial cells of Cajal in the deep muscular plexus of the ileum and the submuscular plexus of the colon also appeared immunoreactive. In neurones, arginosuccinate synthetase and nNOS were usually co-localized. NADPH diaphorase activity was present in LOS and likely in pylorus, but not in muscularis externa of ileum or colon. We conclude that resynthesis of L-arginine probably occurs in enteric nerves, interstitial cells of Cajal (ICC) and LOS muscle; also apparently in some cells without NOS to utilize it.

Animals↗
PubMed2000

Comparison of celecoxib metabolism and excretion in mouse, rabbit, dog, cynomolgus monkey and rhesus monkey.

1. The metabolism and excretion of celecoxib, a specific cyclooxygenase 2 (COX-2) inhibitor, was investigated in mouse, rabbit, the EM (extensive) and PM (poor metabolizer) dog, and rhesus and cynomolgus monkey. 2. Some sex and species differences were evident in the disposition of celecoxib. After intravenous (i.v.) administration of [14C]celecoxib, the major route of excretion of radioactivity in all species studied was via the faeces: EM dog (80.0%), PM dog (83.4%), cynomolgus monkey (63.5%), rhesus monkey (83.1%). After oral administration, faeces were the primary route of excretion in rabbit (72.2%) and the male mouse (71.1%), with the remainder of the dose excreted in the urine. After oral administration of [14C]celecoxib to the female mouse, radioactivity was eliminated equally in urine (45.7%) and faeces (46.7%). 3. Biotransformation of celecoxib occurs primarily by oxidation of the aromatic methyl group to form a hydroxymethyl metabolite, which is further oxidized to the carboxylic acid analogue. 4. An additional phase I metabolite (phenyl ring hydroxylation) and a glucuronide conjugate of the carboxylic acid metabolite was produced by rabbit. 5. The major excretion product in urine and faeces of mouse, rabbit, dog and monkey was the carboxylic acid metabolite of celecoxib.

Animals↗
PubMed2000

Immune responses to hepatitis C virus structural and nonstructural proteins induced by plasmid DNA immunizations.

DNA-based immunizations have been used to elicit cellular immunity to hepatitis C virus (HCV) proteins in mice. Mice were immunized by intramuscular or intradermal injections of plasmid DNA derived from a near-full-length HCV genotype 1b genomic clone (pRC/B2) or individual genomic clones. These immunizations induced cytotoxic T lymphocytes (CTLs), as revealed in standard chromium-release assays that used syngeneic peptide-pulsed or transfected target cells. These assays identified four CTL epitopes within the capsid, E1, and E2 regions of the polyprotein sequence of HCV genotype 1a that were cross-reactive with HCV genotype 1b. Additionally, CTLs derived from mice immunized with either NS3 or NS5 specifically lysed target cells sensitized to either the genotype 1a or 1b gene products. Nucleic acid immunizations also generated humoral immunity to HCV proteins, as detected by anti-HCV reactivity to NS3 and capsid in ELISAs and immunoblot assays.

Animals↗
PubMed2000

The role of lung scintigraphy in the diagnosis of nephrotic syndrome with pulmonary embolism.

PURPOSE: Patients with nephrotic syndrome (NS) have an increased tendency to develop thrombosis and even to progress to pulmonary embolism (PE). This study was performed to determine the incidence of PE in NS with severe hypoalbuminemia and to investigate the possible role of ventilation-perfusion (V/Q) lung scans to evaluate these patients. METHODS: Eighty-nine patients with NS (serum albumin concentration < 2 g/dl) and risk factors for PE were studied. In all patients, the probability that PE would develop was assessed based on the results of V/Q lung scans (Xe-133 for ventilation and Tc-99m MAA for perfusion imaging). The lung scans were judged using the modified Prospective Investigation of Pulmonary Embolism Diagnosis criteria. In 25 (28%) patients whose lung scans showed an intermediate or low probability, but for whom there was a strong clinical indication of PE, pulmonary angiography was performed. The patients' clinical symptoms and signs on initial examination were observed. Additional examinations included electrocardiograms, chest radiography, and hematochemical tests such as albumin, blood urea nitrogen, creatinine, cholesterol, triglycerides, fibrinogen, antithrombin III, prothrombin time, and activated partial thromboplastin time. RESULTS: Based on the findings of lung scans, 19 (21%) of the patients were categorized as having a high probability of PE. However, pulmonary angiography found that 10 (11%) other patients had PE despite having lung scan findings categorized as intermediate or low probability of PE. Except for plasma fibrinogen and antithrombin III levels, neither the clinical symptoms and signs, electrocardiogram findings, chest radiograph results, nor values of hematochemical testing were consistent with the occurrence of PE in these 29 patients. CONCLUSION: The results of this study suggest that PE is not a rare complication in patients with NS, and is usually clinically silent. In this series, the occurrence of PE did not appear to be always correlated with the clinical or hematochemical severity of NS, except for the association with elevated levels of fibrinogen and antithrombin III. When treating the clinical symptoms of patients with NS, physicians should be alert to the possible complication of PE. Serial V/Q lung scans may provide valuable clues in the evaluation of these patients.

Angiography↗
PubMed2000

Krypton-81m ventilation and technetium-99m macroaggregated albumin perfusion scintigraphy for detection of pulmonary embolism: the first experience in Taiwan.

BACKGROUND: This study was designed to assess whether the self-made (Institute of Nuclear Energy Research, Taiwan) krypton (Kr)-81m could be used as a ventilation agent to detect patients with suspected pulmonary embolism (PE). In addition, xenon (Xe)-133 ventilation scintigraphy was also performed for comparison. METHODS: Forty patients with suspected PE were studied. Each patient received Kr-81m ventilation, Xe-133 ventilation and technetium (Tc)-99m macroaggregated albumin (MAA) perfusion studies on the same day. Images were judged using the criteria of the modified Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED). For those with a high or intermediate probability of PE on lung scans and normal pulmonary function tests, anticoagulants were given and patients were monitored with Tc-99m MAA perfusion studies after treatment. The final diagnosis was based on chest radiography, pulmonary function tests and lung scans. RESULTS: All 40 patients successfully underwent lung scans. Of these, 11 had PE. Ten of the 11 cases were detected using Kr-81m ventilation and Tc-99m MAA perfusion studies, resulting in a sensitivity of 91%. Seven of 11 cases were detected using Xe-133 ventilation and Tc-99m MAA perfusion studies, resulting in a sensitivity of 64%. Of the 11 patients with PE, four had PE alone; Kr-81m and Xe-133 results agreed in three patients, but Kr-81m detected PE in the remaining patient. Of the remaining seven patients who suffered from PE with obstructive airway disease, Kr-81m and Xe-133 agreed in four, but Kr-81m detected PE in another two patients and one case was missed by both studies. CONCLUSIONS: Self-made Kr-81m was safe and effective for ventilation scintigraphy in humans. When Kr-81m was used for the detection of PE, it was particularly advantageous when PE occurred in small areas of the lungs or when the patient with PE had concurrent obstructive airway disease.

Adolescent↗
PubMed2000

Type III tympanoplasty with cartilage obliteration for cholesteatoma surgery.

BACKGROUND: The main objective of cholesteatoma surgery is complete eradication of the disease. Another goal is to preserve hearing acuity. We reviewed type III tympanoplasty with cartilage obliteration for cholesteatomatous ears. To evaluate the role of ossiculoplasty, the functional results of classic and modified type III tympanoplasties were compared. METHODS: Thirty-six cholesteatomatous ears undergoing type III tympanoplasty with cartilage obliteration were reviewed. The same operator performed these operations from 1984 until 1995. According to the CAO staging system, there were five early, 16 moderate and 15 advanced-stage cases of cholesteatoma. Using the anterior approach, all operations were canal-wall-down type III tympanoplasties with "tailored" open cavity and cartilage obliteration. There were 24 classic and 12 modified type III tympanoplasties. RESULTS: The average follow-up duration was 7.2 years. Neither recidivistic cholesteatoma nor retraction pocket was observed postoperatively. There was an improvement in atelectatic score after surgery. The mean postoperative air-bone gap (ABG) was 15.8 +/- 10.7 dB and the mean closure of the ABG was 4.0 +/- 14.3 dB. After the disease stage and preoperative hearing status were adjusted using regression analysis, there was no significant difference in hearing results between ears that underwent classic or modified type III tympanoplasties. CONCLUSIONS: We performed the canal-wall-down tympanoplasty with cartilage obliteration using the anterior approach for treatment of cholesteatoma. Such surgical techniques eradicate the cholesteatoma, prevent its recurrence and create a clean ear. Hearing reconstruction can also be accomplished in a single-stage procedure offering a serviceable hearing acuity.

Adolescent↗
PubMed2000

[Studies on the photosynthetic characteristics of wheat variants by introduction sorghum DNA].

Spring wheat Longchun No. 13 and Ganmai No. 8 were introduced by sorghum DNA via pollen tube pathway, and two stable progenies (89,122 and 89,144 respectively) were obtained through selection for several years. The results of photosynthetic analysis showed that photosynthetic rate (P) and photosynthetic/transpiration rate (E/P) of 89,122 and 89,144 were mediated between their recipients and donor respectively, which demonstrated stronger photosynthetic efficiency than their receptors. However, the delta 13 C values in assimilates from 89,122, 89,144 and their maternal wheat cultivars G8 and L13 were approximately same, and they were significant different from sorghum. The chlorophyll content and the ratio of Chla/Chlb of them also showed that wheat cultivars and sorghum were different. It might demonstrated that the stronger photosynthetic efficiency of the progenies was due to their higher Calvin cycle metabolism efficiency rather than their carbon-fixation pathway difference. On the other hand, it also suggested that the distant genetic materials of the sorghum affected the photosynthetic characteristics of 89122 and 89144.

DNA, Plant↗
PubMed2000

[The effect of functional endoscopic sinus surgery on mucociliary clearance].

OBJECTIVE: To explore the effect of functional endoscopic sinus surgery(FESS) on the mucociliary clearance of nasal mucosa. METHOD: 105 patients suffered from chronic sinusitis and undergone FESS from Jan. 1998 to Dec. 1998 were staged and analyzed according to the standard set up in Haikou in 1997. The nasal mucociliary transport rate (MTR) was measured by "saccharin" before, three months and six months after surgery. RESULT: 1. The difference of the stages for chronic sinusitis affected directly the surgical result. 2. The difference of properties, limits and extents of pathological changes in sinuses was significantly associated with the MTR. The MTR showed a marked reduction in stage II-II, II-III and III. The MTR was increased after surgery. 3. The difference of the stages affected directly the recovery of MTR. The MTR in stage I-I, I-II, I-III and II-I recovered more quickly. CONCLUSION: The MTR of nasal mucosa tended to recover after FESS. The study confirmed that the present staging system for chronic sinusitis was seasonable. We therefore propose the "saccharin" technique as a simple, safe, reliable and objective method of assessing the results of surgery.

Adolescent↗
PubMed1999

Gap junctions in intestinal smooth muscle and interstitial cells of Cajal.

This manuscript reviews gap junctions' roles in control of intestinal motility. Gap junctions (GJs) of small intestine (SmIn) are found between circular muscle (CM) cells, between interstitial cells of Cajal (ICC) of deep muscular plexus (DMP) and between them and adjacent outer circular muscle (OCM). GJs between longitudinal muscle (LM) cells or between cells of inner circular muscle (ICM) have not been reported. Occasional GJs have been reported between ICC of the myenteric plexus (MyP) and rarely between these ICC and adjacent LM or CM cells, or between ICC within CM and smooth muscle cells. In the colon (Co) of several species a special network of ICC lines the inner border of CM, the submuscular plexus (SP). GJs are found between ICCs and between them and CM cells. The ICC of MyP of Co are associated with LM and CM; occasional GJs exist between ICC and each muscle layer. Small GJs are missed by electron microscopy or light microscopic Immunocytochemistry. Therefore, GJ coupling may exist without demonstrated GJs. The consequences for the pacemaking functions of ICC networks of varied densities of GJ between ICC and between ICC of MyP or DMP or of SP and CM are considered. Connexins (Cxs) that compose intestinal GJs may affect coupling, but are incompletely known. Understanding of the role of GJs in coordinating intestinal motility requires knowing: (1) what passes through gap junctions to couple ICC to smooth muscle cells; (2) what Cx with what conductances and what modulatory controls connect ICC and smooth muscle cells; (3) whether smooth muscles can generate slow waves independent of ICC networks; and (4) what happens to motility, slow waves, and IJPs when GJs are selectively uncoupled.

Animals↗
PubMed1999

P- and E-selectin-deficient mice are susceptible to cerebral ischemia-reperfusion injury.

We examined brain sections from P- and E-selectin-deficient mice (-/-) and their nontransgenic littermates (+/+) after focal cerebral ischemia and reperfusion (I/R) tissue injury. There was no difference in the subsequent infarct volume after 3 h of ischemia and 21 h of reperfusion. These data indicate that selectin-independent mechanisms mediate tissue injury after a prolonged period of transient focal ischemia.

Animals↗
PubMed1999

Irreversible inhibition of epidermal growth factor receptor tyrosine kinase with in vivo activity by N-[4-[(3-bromophenyl)amino]-6-quinazolinyl]-2-butynamide (CL-387,785).

It has been shown previously that 4-anilino quinazolines compete with the ability of ATP to bind the epidermal growth factor receptor (EGF-R), inhibit EGF-stimulated autophosphorylation of tyrosine residues in EGF-R, and block EGF-mediated growth. Since millimolar concentrations of ATP in cells could reduce the efficacy of 4-anilino quinazolines in cells and the activity of these compounds would not be sustained once they were removed from the body, we reasoned that irreversible inhibitors of EGF-R might improve the activity of this series of compounds in animals. Molecular modeling of the EGF-R kinase domain was used to design irreversible inhibitors. We herein describe one such inhibitor: N-[4-[(3-bromophenyl)amino]-6-quinazolinyl]2-butynamide, known as CL-387,785. This compound covalently bound to EGF-R. It also specifically inhibited kinase activity of the protein (IC50 = 370+/-120 pM), blocked EGF-stimulated autophosphorylation of the receptor in cells (ic50 approximately 5 nM), inhibited cell proliferation (IC50 = 31-125 nM) primarily in a cytostatic manner in cell lines that overexpress EGF-R or c-erbB-2, and profoundly blocked the growth of a tumor that overexpresses EGF-R in nude mice (when given orally at 80 mg/kg/day for 10 days, daily). We conclude that CL-387,785 is useful for studying the interaction of small molecules with EGF-R and may have clinical utility.

Animals↗
PubMed1999

Overexpression in Escherichia coli and characterization of the chloroplast triosephosphate isomerase from spinach.

An important Calvin cycle enzyme, chloroplast triosephosphate isomerase (cpTPI) from spinach, has been cloned and expressed in up to 15% of the total cell protein using the P(L) expression vector in Escherichia coli. An even higher level expression, up to 36% of the total protein, was achieved by replacing the nucleotide sequence between the ribosomal binding site and the initial codon, ATG, with an AT-rich sequence. Computer modeling revealed that the moderate change in the standard free energy (5'-DeltaG degrees ) of mRNA secondary structure in the translation initial region might be the major factor which led to the later high-level expression. The overexpressed spinach cpTPI was soluble and fully active and was able to be purified beyond 95% purity by DEAE-Sepharose and Sephadex G-75, and around 55 mg of purified enzymes was obtained from 1 liter of cultured bacteria. With d-glyceraldehyde 3-phosphate as substrate, K(m (D-3-P)) is 0. 68 mM, V(max (G-3-P)) is 3.16 x 10(4) micromol/min. mg, and K(cat (G-3-P)) is 4.51 x 10(3)/s; with dihydroxyacetone phosphate as substrate, the corresponding values are 7.27 mM, 1.04 x 10(3) micromol/min. mg, and 1.16 x 10(2)/s, respectively.

Base Sequence↗
PubMed1999

Classification of ion mobility spectra by functional groups using neural networks.

Neural networks were trained using whole ion mobility spectra from a standardized database of 3137 spectra for 204 chemicals at various concentrations. Performance of the network was measured by the success of classification into ten chemical classes. Eleven stages for evaluation of spectra and of spectral pre-processing were employed and minimums established for response thresholds and spectral purity. After optimization of the database, network, and pre-processing routines, the fraction of successful classifications by functional group was 0.91 throughout a range of concentrations. Network classification relied on a combination of features, including drift times, number of peaks, relative intensities, and other factors apparently including peak shape. The network was opportunistic, exploiting different features within different chemical classes. Application of neural networks in a two-tier design where chemicals were first identified by class and then individually eliminated all but one false positive out of 161 test spectra. These findings establish that ion mobility spectra, even with low resolution instrumentation, contain sufficient detail to permit the development of automated identification systems.

Alcohols↗
PubMed1999

Toxicological and antioxidant effects of short-term dehydroepiandrosterone injection in young rats fed diets deficient or adequate in vitamin E.

This study examined the in vivo antioxidant and/or prooxidant effect of short-term dehydroepiandrosterone (DHEA) injection and the effect of dietary vitamin E. Male Sprague-Dawley rats (4 wk old) were fed vitamin E-deficient or vitamin E-adequate (30 mg DL-alpha-tocopheryl acetate/kg) diet for 4 weeks followed by intraperitoneal injection of DHEA for 1 week. The results showed that DHEA injection caused a dose-dependent decrease in body weight, and this effect was more pronounced in vitamin E-deficient rats. In contrast, DHEA injection significantly increased liver, kidney and adrenal weights. Hepatic vitamin E content was significantly lowered by vitamin E deficiency, which led to significantly increased ex vivo and iron-induced lipid peroxidation. DHEA injection did not affect hepatic vitamin E content but significantly decreased ex vivo and iron-induced lipid peroxidation in vitamin E-deficient rats. Hepatic total sulfhydryl (SH) groups and non-protein SH contents were not affected by vitamin E but were significantly increased by DHEA injection, which at 100 mg/kg was not more effective than at 50 mg/kg. Hepatic glutathione S-transferase (GST) activity was significantly decreased by DHEA, but vitamin E alleviated such a decrease. DHEA injection significantly increased hepatic glucose 6-phosphate dehydrogenase (G6PD) activity, and the effect was dose dependent in vitamin E-deficient rats. Thus, DHEA may compensate for vitamin E deficiency in vivo, and this effect is masked when dietary vitamin E is adequate. The antioxidant effect of DHEA is accompanied by decreased body weights, enlarged (fat-laden) tissues and altered activities of hepatic GST and G6PD.

Analysis of Variance↗
PubMed1999

Comparative investigation on spindle behavior and MPF activity changes during oocyte maturation between gynogenetic and amphimictic crucian carp.

The spindle behavior and MPF activity changes in the progression of oocyte maturation were investigated and compared with cytological observation and kinase assay between gynogenetic silver crucian carp and amphimictic colored crucian carp. MPF activity was measured by using histone H1 as phosphorylation substrate. There were two similar oscillatory MPF kinase activity changes during oocyte maturation in two kinds of fishes with different reproductive modes, but there existed some subtle difference between them. The subtle difference was that the first peak of MPF kinase activity was kept to a longer-lasting time in the gynogenetic silver crucian carp than in the amphimictic colored crucian carp. It was suggested that the difference may be related to the spindle behavior changes, such as tripolar spindle formation and spindle rearrangement in the gynogenetic crucian carp.

Animals↗