Biomedical subjects

Y H Wu

Publications and source records attributed to Y H Wu.

At least 19 recordsLinked to original sources

PubMed2006

Raman spectroscopic investigation of carbon nanowalls.

Two-dimensional carbon nanowalls (CNWs) were prepared by microwave plasma-enhanced chemical-vapor deposition and scanning electron microscopy was used to observe their morphologies. The Raman observations of different sample orientations and polarizations show that CNWs are well crystallized. Micro-Raman scattering measurements were also carried out with different excitation laser lines (325, 488, 514, 532, and 633 nm). The D band shows a very strong shift of 46.19 cm(-1)eV with excitation laser energy and this has been explained by the double resonance effect. The decreasing intensity ratios IDIG and ID'/IG with increasing laser excitation energy were detected and discussed.

Journal Article↗

PubMed2004

In vitro mutagenesis of Xanthomonas campestris alpha-amylase gene by partially replacing deoxythymidine triphosphate with 5-bromo-2'-deoxyuridine-5'-triphosphate using a PCR technique.

Three mutants of the wild type alpha-amylase gene from Xanthomonas campestris pv. campestris 8004 were obtained using a PCR technique in which deoxythymidine triphosphate (dTTP) was partially replaced by 5-bromo-2'-deoxyuridine-5'-triphosphate (BrdUTP), at an optimal dTTP:BrdUTP ratio of 1000:1. Of thre three mutants that were obtained and which were sequenced, one mutant with 40 times higher activity than the wild type alpha-amylase gene product was obtained by using primary PCR products as a template for a second PCR reaction.

Cloning, Molecular↗

PubMed2004

Use of a molar clamp to isolate two adjacent single-rooted teeth: a clinical aid.

AIM: To emphasize the importance of rubber dam isolation in root canal treatment and to present a technique to simultaneously isolate two single-rooted teeth using a molar clamp. SUMMARY: Isolation of two adjacent teeth with inadequate tooth structure is a challenge. The split-dam technique or using two clamps have drawbacks. This report presents a technique to simultaneously isolate two adjacent single-rooted teeth that are difficult to isolate by conventional methods. Its advantages are efficiency, reduction of radiation exposure, better access, good visibility and isolation. KEY LEARNING POINTS: The basis of this technique is to isolate two teeth as two roots of a molar tooth. The indications for this technique are two adjacent prepared crowns and crownless roots. The appropriate molar clamp can be selected on the basis of the mesial-distal clamp jaw distance being equal to the mesial-distal spacing of the two roots. The buccal-lingual jaw distance of the clamp should be smaller than the dimension of the roots to provide adequate retention.

Humans↗

PubMed2003

Arsenite-induced nitric oxide generation is cell cycle-dependent and aberrant in NBS cells.

Exposure to arsenic has been reported to cause DNA damage and eventually the occurrence of bladder, lung and skin cancers. A previous report has demonstrated that arsenite-induced phosphorylation of Mre11, a protein involved in the repair of DNA double strand breaks (DSBs), is M phase-dependent and requires the Nijmegen breakage syndrome (NBS) protein, NBS1 [DNA Repair 1 (2002) 137]. Furthermore, arsenite treatment arrests cells at the M phase and the cells eventually go through apoptosis [Biochemical Pharmacology 60 (2000) 771]. Here we demonstrate that arsenite treatment enhances the generation of nitric oxide (NO), and that the enhanced NO generation is dominant at the G2/M phase. Arsenite-induced NO generation is impaired in DSB repair-defective NBS cells, but not in NBS1-reconstituted NBS cells, suggesting NBS1 is required for effective NO generation. In summary, our study showed, for the first time, that arsenite-induced NO generation is cell-cycle- and NBS1-dependent.

Arsenites↗

PubMed2001

Co-administration of dextromethorphan during pregnancy and throughout lactation significantly decreases the adverse effects associated with chronic morphine administration in rat offspring.

In this study, we have focused our investigation of the facts whether co-administration of a NMDA antagonist dextromethorphan (DM) with morphine during pregnancy and throughout lactation could prevent the adverse effects associated with chronic morphine administration in rat offspring. Adult female Sprague-Dawley rats were randomly separated into four groups and were received subcutaneous injection of either saline, morphine, morphine + dextromethorphan or dextromethorphan twice a day and progressively increased 1 mg/kg at 7-day intervals from a beginning dose of 2 mg/kg for both morphine and dextromethorphan. The rats were mated between days 7 and 8. Administration of drugs was continued during pregnancy. After rat offspring were born, the doses of morphine or dextromethorphan injected into the maternal rats were increased by 1 mg/kg every two weeks till the offspring were 30 day old. The results showed that mortality of morphine group is much higher than control group. The offspring of morphine group weighed significantly less than control group on postnatal day 14 (p14), p30 or p60. The antinociceptive effect of morphine on p14 rats was reduced in the morphine group and indicated the development of morphine tolerance. The hippocampal NMDA receptor densities have been shown decreased on p14 rats. The precipitated withdrawal symptoms were assessed on p7 rats. Rats in morphine group showed greater frequency of abdominal stretch and wet dog shake in 2 hr than control group. On the other hand, co-administration of DM with morphine effectively prevented all these adverse effects of morphine to the offspring rats. DM co-administered with morphine also partially prevented the development of morphine tolerance in maternal rats. If this effect of dextromethorphan is applied to clinical pregnant patients with morphine addiction or chronic pain, it will have a great value for the benefit of their children.

Analgesics, Opioid↗

PubMed2001

Abrin triggers cell death by inactivating a thiol-specific antioxidant protein.

Abrin A-chain (ABRA) inhibits protein synthesis by its N-glycosidase activity as well as induces apoptosis, but the molecular mechanism of ABRA-induced cell death has been obscure. Using an ABRA mutant that lacks N-glycosidase activity as bait in a yeast two-hybrid system, a 30-kDa antioxidant protein-1 (AOP-1) was found to be an ABRA(E164Q)-interacting protein. The interaction was further confirmed in vitro by a glutathione S-transferase pull-down assay. The colocalization of endogenous AOP-1 and exogenous ABR proteins in the cell was demonstrated by confocal immunofluorescence. We also demonstrated that ABRA attenuates AOP-1 antioxidant activity in a dose-dependent manner and the intracellular level of reactive oxygen species (ROS) increases in ABR-treated cells. Moreover, ROS scavengers N-acetylcysteine and 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl delayed programmed cell death. This indicates that ROS are important mediators of ABR-induced apoptosis. When ectopically expressed, AOP-1 blocked the release of cytochrome c and prevented apoptosis in ABR-treated cells. These findings suggest that the binding of ABRA to AOP-1 promotes apoptosis by inhibiting the mitochondrial antioxidant protein AOP-1, resulting in the increase of intracellular ROS and the release of cytochrome c from the mitochondria to the cytosol, which activates caspase-9 and caspase-3.

Abrin↗

PubMed2001

Transgenics in crops.

With rapid world population growth and declining availability of fresh water and arable land, a new technology is urgently needed to enhance agricultural productivity. Recent discoveries in the field of crop transgenics clearly demonstrate the great potential of this technology for increasing food production and improving food quality while preserving the environment for future generations. In this review, we briefly discuss some of the recent achievements in crop improvement that have been made using gene transfer technology.

Agriculture↗

PubMed2001

Molecular characterisation of very virulent infectious bursal disease viruses in Taiwan.

The very virulent infectious bursal disease virus (vv IBDV) RNA in the bursa of Fabricius and spleen from experimentally infected chickens or field samples was detected by in situ hybridisation (ISH) with subsequent reverse transcription (RT)-polymerase chain reaction (PCR) and sequence analysis. The VP 2 gene of vv IBDV was detected by ISH in infected chicken tissues with a cloned digoxigenin (DIG)-labelled cDNA probe. To verify ISH, RT - PCR was used to amplify two 643- and 500-base pair fragments on the VP 2 gene of IBDV in the bursa of Fabricius. With all isolates, two c DNA fragments of 643 and 500 bp long, respectively, were generated as expected and further confirmed the specificity of ISH. Analysis of the hypervariable region (HVR) of the VP 2 gene revealed that a serine-rich heptapeptide SWSASGS located at amino acids 326-332 was conserved in recent Taiwanese strains, and two amino acid substitutions were found in the classical Taiwanese strains at positions 330M and 331W. Three amino acids were unique to the vv strains at positions 222A, 256I and 294I, compared with classical and variant strains. Sequence and phylogenetic analysis showed that the recent Taiwanese strains were closely related, very similar to vv IBDV s from Europe, China, Japan, and Africa, and distantly related to the Taiwanese classical strains.

Amino Acid Sequence↗

PubMed2001

Correlation of mutational analysis to clinical features in Taiwanese patients with Gilbert's syndrome.

OBJECTIVES: Mutations in the promoter as well as in the coding region of the bilirubin UDP-glucuronosyltransferase gene (UGT1A1) have been found to be associated with Gilbert's syndrome. However, the genetic basis of Gilbert's syndrome in our population and correlation of these mutations to fasting serum bilirubin levels in patients with Gilbert's syndrome remain to be clarified. METHODS: We applied polymerase chain reaction-based direct-sequencing assays to examine mutations in UGT1A1 gene in 20 unrelated Gilbert's patients and in a family with Gilbert's syndrome. RESULTS: We studied three mutations that were previously reported to be associated with Gilbert's syndrome (i.e., the TATAA-box mutation, Gly71Arg, and Pro229Gln) in 20 patients with Gilbert's syndrome. Of the patients, 16, five, and six were found to have the TATAA-box, Gly71Arg and Pro229Gln mutations, respectively. Seven patients had simultaneous mutations both in the TATAA box and in the coding region. Of note, all six patients with Pro229Gln also had the TATAA-box mutation. Localization of Pro229Gln on the allele containing the TATAA-box mutation was demonstrated in a family with Gilbert's syndrome. The patients simultaneously heterozygous for both the TATAA-box mutation and Gly71Arg usually had serum bilirubin levels similar to those found in the patients homozygous for the TATAA-box mutation, but usually higher than those found in the patients heterozygous for the TATAA-box mutation alone. On the other hand, concurrence of Pro229Gln in patients with TATAA-box mutation or with Gly71Arg did not significantly affect serum bilirubin levels. CONCLUSIONS: The TATAA-box mutation and Gly71Arg are the major causes for Gilbert's syndrome in our population. Concurrence of mutations of Gly71Arg and TATAA-box usually exerts a synergistic effect on hyperbilirubinemia. Pro229Gln, which is regularly linked to the TATAA-box mutation, may not have a significant effect on serum bilirubin levels.

Adolescent↗

PubMed2001

Impaired interaction of mutant thyroid hormone receptors associated with human hepatocellular carcinoma with transcriptional coregulators.

Thyroid hormone (T(3)) exerts its many biological activities through interaction with specific nuclear receptors (TRs) that function as ligand-dependent transcription factors at genes that contain a thyroid hormone response element (TRE). Mutant TRs have been detected in human hepatocellular carcinoma cell lines and tissue, but their contribution to carcinogenesis has remained unclear. The interaction of four such mutant TRs (J7-TRalpha1, J7-TRbeta1, H-TRalpha1, and L-TRalpha1) with transcriptional coregulators has now been investigated. With the exception of J7-TRalpha1, which in the absence of T(3) exhibited transcriptional silencing activity with a TRE-reporter gene construct in transfected cells, the mutant TRs had little effect (compared with that of wild-type receptors) on transcriptional activity of the reporter gene in the absence or presence of T(3), of the transcriptional corepressors SMRT, NCoR or of the transcriptional coactivator SRC. Electrophoretic mobility-shift assays revealed that, in the presence of T(3), the J7-TRss1 mutant did not interact with SRC, whereas J7-TRalpha1 and H-TRalpha1 exhibited reduced abilities to associate with this coactivator and L-TRalpha1 showed an ability to interact with SRC similar to that of wild-type TRalpha1. The dominant negative activity of the mutant TRs in transfected cells appeared inversely related to the ability of the receptors to interact with SRC. Whereas J7-TRss1, H-TRalpha1, and L-TRalpha1 did not interact with SMRT, and NCoR. J7-TRalpha1 bind to corepressors but failed to dissociate from them in the presence of T(3). These aberrant interactions between the mutant TRs and transcriptional coregulators may contribute to the highly variable clinical characteristics of human hepatocellular carcinoma.

Animals↗

PubMed2001

[Counteraction effect of intermittent -Gx on changes of responsiveness of basilar artery in tail-suspended rats].

OBJECTIVE: To investigate counteracting effects of intermittent -Gx exposure on changes of responsiveness of basilar artery in tall-suspended rats. METHOD: Rats tail-suspended for 3 wk were daily subjected to 1 h 1.5 G or 2.6 G centrifugation, simulating -Gx exposure of various G values. Responses of perfused isolated basilar arterial rings to KCl was examined. RESULT: Maximal isometric contractile response to KCl were significantly enhanced in arterial rings isolated from 3 wk tail-suspended rats as compared with that from simultaneous control rats (P < 0. 05). However, maximal isometric contractile responses to KCl of arterial rings isolated from 3 wk tail-suspended plus daily -Gx exposure rats were no difference as compared with that from simultaneous control rats, and were significantly decreased (P < 0.05) as compared with that from 3 wk tail-suspended rats. CONCLUSION: Daily intermittent -Gx exposure as a countermeasure to prevent the effects of simulated weightless on changes in responsiveness of basilar artery from tail-suspended rats was valid.

Animals↗

PubMed2000

Utilizing predictions of early prostate-specific antigen failure to optimize patient selection for adjuvant systemic therapy trials.

PURPOSE: Prostate-specific antigen (PSA) failure within 2 years after radical prostatectomy (RP) has been shown to be a clinically significant predictor of distant failure. This study was performed to estimate 2-year PSA failure rates on the basis of readily available clinical and pathologic factors to identify patients for whom effective adjuvant systemic therapy is needed. PATIENTS AND METHODS: A Cox regression multivariable analysis was used to determine whether the percentage of positive prostate biopsies, PSA level, and the pathologic findings at RP in 1,728 men provided clinically relevant information about PSA outcome after RP. A bootstrapping technique with 2,000 replications was used to provide 95% confidence intervals for the predicted 2-year PSA failure rates, which were determined on the basis of the independent clinical and pathologic predictors of PSA outcome. RESULTS: The independent predictors of time to PSA failure included a percentage of positive prostate biopsies of greater than 34% (P: < or =.009), PSA level greater than 10 ng/mL (P: < or =.01), seminal vesicle invasion (P: =. 02), prostatectomy Gleason score of 8 to 10 (P: =.04), and positive surgical margins (P: =.0001). Predictions of 2-year PSA failure rates and bootstrap estimates of the 95% confidence intervals were arranged in a tabular format, stratified by independent clinical and pathologic predictors of PSA outcome. CONCLUSION: Patients who are most likely to benefit from effective adjuvant systemic therapy after RP can be identified using readily available clinical and pathologic data.

Biopsy↗

PubMed2000

Combination of the preoperative PSA level, biopsy gleason score, percentage of positive biopsies, and MRI T-stage to predict early PSA failure in men with clinically localized prostate cancer.

OBJECTIVES: Early (2 years or less) prostate-specific antigen (PSA) failure has been shown to predict for distant failure. The independent clinical predictors of time to postoperative PSA failure were used to identify prostate cancer patients at high risk for early PSA failure. METHODS: A Cox regression multivariable analysis was used to determine whether additional predictive information was provided by the endorectal coil magnetic resonance imaging (erMRI) T-stage when controlling for the established prognostic factors in predicting the time to postoperative PSA failure in 977 men with palpable (T2) or PSA-detected (T1c) prostate cancer. RESULTS: Preoperative PSA (P = 0.0001), percentage of positive prostate biopsies (P= 0.0001), erMRI T-stage (P = 0.0001), biopsy Gleason score (P = 0.0015), and clinical stage T2c disease (P = 0.004) were independent predictors of time to postoperative PSA failure. Two-year PSA failure rates derived from the Cox regression model and bootstrap estimates of the 95% confidence intervals are presented in nomogram format stratified by the preoperative PSA, percentage of positive prostate biopsies, erMRI T-stage, and the biopsy Gleason score. CONCLUSIONS: Patients at high risk for early PSA failure and subsequent distant progression include men with erMRI T3 disease and 3 or more of 6 cores positive for a Gleason score 6 or higher disease when the PSA is more than 10 but not more than 20 ng/mL and any Gleason score when the PSA is more than 20 ng/mL. Men with erMRI T2 disease and 3 or more of 6 cores positive for a Gleason score 8 or higher disease and who have a PSA more than 20 ng/mL are also at high risk. Neoadjuvant therapy trials in these select patients may be justified.

Biomarkers, Tumor↗

PubMed2000

The use of monoclonal antibody probes for the detection of avian reovirus antigens.

Two monoclonal antibodies (MAb), E9 and H3, prepared against avian reovirus (ARV) S1133, were used in an immuno-dot assay to detect ARV antigens from cell culture and from tendon tissue samples of chickens. The limit of viral antigens detected was 8 ng using both MAb probes. The probes detected 10 ARV isolates representing at least two serotypes or pathotypes. The results indicated that these probes had broad specificity. The probes, however, did not cross-react with viral antigens prepared from six unrelated avian viruses. The ARV antigens in tendon tissue samples were detected by both probes, and it is possible, therefore, to use either of the two MAb probes for detection of ARV infections.

Animals↗

PubMed2000

Survey of infectious skin diseases and skin infestations among primary school students of Taitung County, eastern Taiwan.

BACKGROUND: There are no complete records on the prevalence of childhood skin diseases in Taiwan. We conducted a survey of infectious skin diseases and skin infestations among primary school children in Taitung County, which is located in southeastern Taiwan. METHODS: From March 1998 through October 1998, a total of 3,029 students from four rural districts (Changbin, Yanping, Lanyu, and Dawu) and one urban area (Taitung City of Taitung County) were examined by dermatologists. Treatment and instructions for disease care were given immediately after the diagnosis of dermatoses, when appropriate. RESULTS: The most common infectious skin diseases and infestations were pediculosis capitis (12.9%), verruca vulgaris (5.1%), tinea versicolor (4.4%), tinea pedis (4.1%), verruca plantaris (1.8%), and scabies (1.4%). Most skin diseases, including pediculosis capitis, scabies, verruca vulgaris, verruca plantaris, folliculitis, pyoderma, tinea pedis, and tinea versicolor, were significantly more common in rural areas than in the urban area (p < 0.05 for all). Pediculosis capitis was more common among girls (p < 0.001), but tinea pedis and tinea versicolor were more common among boys (p < 0.05). CONCLUSIONS: The prevalence of most skin infections and infestations are much higher in rural Taitung County than in Taitung City. Prevention and treatment of these skin diseases should be reemphasized in the education of teachers, as well as students and their families. Adequate dermatologic training of nurses and physicians and the development of teleconsultation and teledermatology in rural areas might decrease the prevalence of these skin diseases in school children.

Child↗

PubMed2000

Effects of acute exposure to mild or moderate hypoxia on human psychomotor performance and visual-reaction time.

Objective. The aim of this study was to determine whether psychomotor performance and visual reaction time were affected by acute exposure to mild or moderate hypoxia. Method. Eighteen healthy male volunteers performed finger tapping, simple reaction time (SRT) and 4-choice reaction time (CRT) tests at simulated altitude of 300 m (control), 2800 m, 3600 m and 4400 m for 1 h in a hypobaric chamber. Result. SaO2 decreased from 98% (control) to 90%, 82% and 74% respectively at the various altitudes. All the performance parameters showed no significant change after exposure to 2800 m for 1 h relative to ground level (P>0.05). However the mean reaction time of 4-CRT under 3600 m prolonged and performance decreased as compared with baseline value (P<0.05), and the performance decreased further under 4400 m (P<0.01). No significant difference was found in finger tapping and SRT even under exposure to 4400 m for 1 h. Furthermore, no decrease in correct rate were observed at any altitude (P>0.05). Conclusion. The results from this study demonstrated that there were no measurable impairment of visual reaction time and psychomotor performance under exposure to an altitude of 2800 m for 1 h. However, adverse effects on psychomotor performance were observed under 3600 m and over.

Adolescent↗

PubMed2000

[Effects of intermittent +45 degrees head-up-tilt on mechanical parameters of femoral (correction of femural) bone in tail-suspended rats].

Objective. To study the effects of different intermittent +45 degrees head-up-tilt (IHUT) on tail-suspended rats. Method. 28 male SD rats were randomly and equally divided into: control group (C), tail-suspended group (S), IHUT 2 h group (H2), and IHUT 4 h group (H4). On the basis of tail-suspension to simulate weightlessness, H rats were given 2 h or 4 h IHUT each day. The effects of 3 wk IHUT on tail-suspended rats were evaluated by measuring physical and mechanical parameters of the femur. Result. Femoral mass (fresh, dry and ash), diameter, and density (fresh, except H2 group) in S, H2 and H4 rats were declined significantly compared to C rats (P<0.01 or P<0.05). Diameter (P<0.05) and density of femur (P<0.01) in H2 rats were significantly improved compared to S rats. Compared to C rats, the strength and stiffness of femora were obviously weakened (P<0.01) in S rats. Elastic load in H2 rats improved markedly (P<0.05) than those in S group; in H4 group, elastic load, maximum load, and bending toughness coefficient improved significantly (P< 0.01 or P<0.05). Conclusion. Using IHUT, mechanical parameters of weight bearing bones of tail-suspended rats can be improved apparently, by extending the exposure time, mechanical parameters can be improved.

Animals↗

PubMed2000

Effects of acute mild and moderate hypoxia on human mood state.

OBJECTIVE: To explore the effects of acute mild and moderate hypoxia on human mood state. METHOD: The mood states of 18 healthy male volunteers were evaluated by self-assessment questionnaires, profile of mood state (POMS) and state anxiety inventory (S-AI) after random exposure to simulated altitude of 300 m (control), 2800 m, 3600 m and 4400 m for 1 h in a hypobaric chamber. RESULT: The data at 300 m level were taken as the baseline control. The negative mood state factor points (tension, fatigue etc.) increased gradually as the altitude level increased while V (vigor-activity) points had a tendency to decrease (P<0.05 or P<0.01). No significant difference was found in the points of (D, A) even under exposure to 4400 m (P>0.05). At the early period of 2800 m exposure the tension points of POMS and S-AI scores were higher than those of control level (P<0.05) then dropped to baseline level when exposure to this altitude for 1 h. CONCLUSION: Exposure to acute mild hypobaric hypoxia at 2800 m for 1 h has adverse effect on mood state of healthy person and the negative effect was further aggravated with the increment of altitude level.

Adolescent↗