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Y L Guo

Publications and source records attributed to Y L Guo.

At least 37 records · Page 2Linked to original sources
PubMed2001

Evaluation of germ-cell kinetics in infertile patients with proliferating cell nuclear antigen proliferating index.

AIM: To explore the usefulness of proliferating cell nuclear antigen proliferating index (PCNA PI) in the pathological diagnosis and treatment of male infertility. METHODS: Testicular biopsy specimen obtained from 48 cases of male infertility and 2 normal controls were fixed and embedded. The sections were stained with anti-PCNA monoclonal antibodies or haematoxylin/eosin. Proliferating index (PI), expressed as the percentage of germ-cell nuclei positively stained with PCNA antibody, was assessed from more than 20 seminiferous tubules or 600 germ-cells. RESULTS: The infertile patients were divided into 4 groups: Group 1, normal spermatogenesis (14 cases); Group 2, hypospermatogenesis (16 cases); Group 3, germinal arrest (10 cases); Group 4, Sertoli cell only syndrome (8 cases). The PCNA PI of normal control testis was 86.5% (mean value). Group 3 had a significantly lower PCNA PI (29.8%) than normal testis; Group 1 and 2 had similar PIs (82.3% and 82.3%, respectively) as the control testis. PI of the negative control (Group 4) was 0 as no germ-cells were found. CONCLUSION: PCNA PI is useful for assessing germ-cell kinetics, especially for pathological diagnosis of germinal arrest which is difficult to differentiate by routine HE staining technique. In germinal arrest, there is a significantly lowered PCNA PI, which is an indication of DNA synthesis deterioration, suggesting the use of therapies be different from those for hypospermatogenesis.

Adult↗
PubMed2001

[Advances in the research of penile erection and erection dysfunction].

Recent advances in the research on erectile dysfunction (ED) has more clearly explained the mechanism of penile erection, which is a hemodynamic process involving relaxation of corpus cavernosum smooth muscle and related arterials, and NO-cGMP signaling pathway proven to play an important role on modulating the relaxation of corpus cavernosum smooth muscle. Studies on NOS and PDEs not only provide strong evidence for the clinical treatment of ED, but also provide the chance to develop Sildenafil. Although the gene therapy for ED is still in the laboratory stage by now, it may be one of the effective clinical therapies for ED in future.

Cyclic GMP↗
PubMed2000

Semen quality after prenatal exposure to polychlorinated biphenyls and dibenzofurans.

Large-scale poisoning occurred in central Taiwan in 1979 from ingestion of cooking oil contaminated by polychlorinated biphenyls (PCBs) and polychlorinated dibenzofurans. To determine whether in-utero exposure to these chemicals alters reproductive function, all prenatally exposed boys and appropriate controls were contacted for medical examination in 1998. Sperm of exposed children have increased abnormal morphology, reduced motility, and reduced capacity to penetrate hamster oocytes. Whether this will cause reduced fecundity, and how these effects can be extrapolated to the general population exposed to background levels of PCBs and dioxin-like chemicals, warrants further investigation.

Adolescent↗
PubMed2000

The alpha1/2 helical backbone of the prodomains defines the intrinsic inhibitory specificity in the cathepsin L-like cysteine protease subfamily.

Proregions of papain-like cysteine proteases are potent and often highly selective inhibitors of their parental enzymes. The molecular basis of their selectivity is poorly understood. For two closely related members of the cathepsin L-like subfamily we established strong selectivity differences. The propeptide of cathepsin S was observed to inhibit cathepsin L with a K(i) of 0.08 nM, yet cathepsin L propeptide inhibited cathepsin S only poorly. To identify the respective structural correlates we engineered chimeric propeptides and compared their inhibitory specificity with the wild-types. Specificity resided in the N-terminal part, strongly suggesting that the backbone of the prodomain was the underlying structure.

Amino Acid Sequence↗
PubMed2000

Identification and genetic mapping of four novel genes that regulate leaf development in Arabidopsis.

Molecular and genetic characterizations of mutants have led to a better understanding of many developmental processes in the model system Arabidopsis thaliana. However, the leaf development that is specific to plants has been little studied. With the aim of contributing to the genetic dissection of leaf development, we have performed a large-scare screening for mutants with abnormal leaves. Among a great number of leaf mutants we have generated by T-DNA and transposon tagging and ethyl-methae sulfonate (EMS) mutagenesis, four independent mutant lines have been identified and studied genetically. Phenotypes of these mutant lines represent the defects of four novel nuclear genes designated LL1 (LOTUS LEAF 1), LL2 (LOTUS LEAF 2), URO (UPRIGHT ROSETTE). and EIL (ENVIRONMENT CONDITION INDUCED LESION). The phenotypic analysis indicates that these genes play important roles during leaf development. For the further genetic analysis of these genes and the map-based cloning of LL1 and LL2, we have mapped these genes to chromosome regions with an efficient and rapid mapping method.

Arabidopsis↗
PubMed2000

Menstruation and reproduction in women with polychlorinated biphenyl (PCB) poisoning: long-term follow-up interviews of the women from the Taiwan Yucheng cohort.

BACKGROUND: In 1979 in Taiwan, about 2000 people were poisoned by cooking oil contaminated with heat-degraded polychlorinated biphenyls (PCBs). Victims developed chloracne and other symptoms; the illness is called Yucheng (oil disease). The chemicals persist in the victims' bodies and some are toxic to the female reproductive system in experimental animals. METHODS: In 1993-1994, we identified the living Yucheng women and neighbourhood controls and interviewed them about their reproductive experience. Of the 596 living Yucheng women aged 30-59 years, we found 368, and interviewed 356. We identified 329 controls, and interviewed 312. RESULTS: Of the Yucheng women, 16% reported abnormal menstrual bleeding compared to 8% (P < 0.05) of control women; 4.2% versus 1.7% reported a stillbirth since 1979 (P = 0.068). Other characteristics of the menses, fertility, frequency of intercourse, and age at menopause appeared unaffected. More of the Yucheng women reported that one of their offspring had died during childhood (10.2% versus 6.1%, P < 0. 05), and that they had decided to limit childbearing because of health problems (7% versus 2%, P = 0.01). CONCLUSIONS: These findings suggest that high level PCB/polychlorinated dibenzofuran (PCDF) exposure has some effect on female endocrine and reproductive function.

Adult↗
PubMed2000

[The clinical value of click stimuli on the measurement of ipsilateral acoustic reflex thresholds].

OBJECTIVE: To define that click can substitute for pure tone as a stimulus to measure ipsilateral acoustic reflex thresholds, and to find out the effect of probe frequency on acoustic reflex thresholds. METHOD: Using middle ear analyzer (GSI 33, version 2), we measured 23 normal voluntary participants (46 ears) for getting the pure-tone generated ipsilateral acoustic reflex thresholds at different probe frequency and the click evoked ipsilateral acoustic reflex thresholds at click rate 100/s and 180/s for every ear. RESULT: For pure tone, the ipsilateral acoustic reflex thresholds at 500 Hz, 1000 Hz, 2000 Hz, were (84.35 +/- 6.96) dB, (84.65 +/- 5.93) dB, (87.96 +/- 6.36) dB by using 226 Hz probe; (93.13 +/- 6.54) dB, (92.70 +/- 6.33) dB, (93.35 +/- 5.99) dB by using 678 Hz probe; (86.52 +/- 4.72) dB, (87.48 +/- 5.00) dB, (88.30 +/- 6.16) dB by using 1000 Hz probe. For click, the ipsilateral acoustic reflex thresholds at click rate 100/s and 180/s were (89.78 +/- 6.83) dB, (92.07 +/- 7.42) dB by using 226 Hz probe; (90.44 +/- 6.76) dB, (90.65 +/- 6.38) dB by using 678 Hz probe; (88.04 +/- 6.87) dB, (88.69 +/- 7.42) dB by using 1000 Hz probe. The acoustic reflex thresholds for 678 Hz probe were higher than those obtained with 226 Hz and 1000 Hz probes. CONCLUSION: There were no artifact appearance while stimulus had been click at low rate, so click can be used for the measurement of ipsilateral acoustic reflex thresholds.

Acoustic Stimulation↗
PubMed2000

[Effect of solution pH value on the chelation structure of zinc acexamate by electrospray ionization mass spectrometry].

AIM: To study the effect of solution pH value on the chelation structure of zinc acexamate. METHODS: A series of samples at different solution pH values were prepared by 10% HCl or 1 mol.L-1 NH3.H2O. Then API/TOFMS with electrospray ion source was applied to assay the samples. The nitrogen curtain gas and nebulizer gas were adjusted to a constant flow rate of 0.6 microL.min-1 and 2 microL.min-1 respectively. Samples were infused into the electrospray interface using a 500 microL syringe pump at a flow rate of 5 microL.min-1. Mass spectra were acquired in positive ion modes by scanning over the range of m/z 100-1,000. RESULTS: The chelation structure of zinc acexamate is stable at pH 2.54 and it can be easy to form the ion (M + ZnY)+ (Y = CH3CONH(CH2)5COO-) and (2M + Na)+ in this condition. CONCLUSION: The drug is an effective antiulcer agent. It may decrease the acidity of stomach juice, and form a polymer to protect the ulcer.

Aminocaproates↗
PubMed1999

Hydrogen peroxide induces premature acrosome reaction in rat sperm and reduces their penetration of the zona pellucida.

Recent studies have demonstrated that mammalian sperm are capable of generating reactive oxygen species (ROS) and that this activity is significantly accelerated in subfertile subjects. The observed decrease in penetration of zona-intact oocyte might be explained by chemical-induced ROS-related early onset of capacitation and premature acrosome reaction, but the mechanism is not clear. We determine whether zona-intact oocyte penetration capability in rat epididymal sperm was affected by premature acrosome reaction in rat sperm treated with hydrogen peroxide (H2O2) and calcium ionophore A23187 or H2O2 and lysophosphatidyl choline. Chlortetracycline fluorescence assay was used to study the status of acrosome reaction on epididymal sperm. The sperm-oocyte binding and penetration assay was used to evaluate the capability for zona pellucida penetration. There was a positive linear correlation between the frequency of acrosome-reacted sperm and capability of sperm-oocyte binding and penetration in zona-free oocytes. In the zona-intact oocytes, the sperm-oocyte penetration rate was suppressed as the proportions of acrosome-reacted sperm increased. In summary, this study showed that premature acrosome reaction reduced rat sperm's capability of penetrating zona-intact oocytes. However, this reduction is not seen in zona-free oocytes. These findings may provide a basis for understanding the effects of sperm ROS generation on zona pellucida penetration in male reproductive toxicology.

Acrosome Reaction↗
PubMed1999

Epidermal growth factor and angiotensin II regulation of extracellular signal-regulated protein kinase in rat liver epithelial WB cells.

Activation of extracellular signal-regulated protein kinase (ERK) is considered essential for mitogenesis. In the present study, rat liver epithelial WB cells were used to investigate the relative roles of Ca2+, protein kinase C (PKC), and protein tyrosine phosphorylation in mitogenesis and activation of the ERK pathway stimulated by epidermal growth factor (EGF) and angiotensin II (Ang II). The sensitivity of the ERK pathway to Ca2+ was studied by using 1,2-bis (O-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA) to chelate intracellular Ca2+ and a low extracellular Ca2+ concentration to prevent Ca2+ influx. Agonist-induced PKC activation was diminished by inhibition of PKC by GF-109203X (bisindolylmaleimide) or by down-regulation of PKC by long-term treatment of the cells with phorbol myristate acetate (PMA). Our results show that although activation of PKC was critical for mitogenesis induced by Ang II or EGF, the initial activation of ERK by both agonists in these cells was essentially independent of PKC activation and was insensitive to Ca2+ mobilization. This is in contrast to the findings in some cell types that exhibit a marked dependency on mobilization of Ca2+ and/or PKC activation. On the other hand, an obligatory tyrosine phosphorylation step for activation of ERK was indicated by the use of protein tyrosine kinase inhibitors, which profoundly inhibited the activation of ERK by EGF, Ang II, and PMA. Additional experiments indicated that tyrosine phosphorylation by a cytosolic tyrosine kinase may represent a general mechanism for G-protein coupled receptor mediated ERK activation.

Angiotensin II↗
PubMed1999

Recent trend of polychlorinated dibenzo-p-dioxins and their related compounds in the blood and sebum of Yusho and Yu Cheng patients.

We investigated the levels of polychlorinated dibenzo-p-dioxins (PCDDs) and their related compounds in blood and sebum from Yusho and Yu-Cheng patients and findings compared with those of normal subjects. Concentrations of these compounds in blood and sebum still were obviously reflected the chemical concentration in the causal rice oil ingested 17 or 26 years since the outbreak. In addition, sebum form the body surface was the most useful sample for monitoring the amount of chemicals contaminating the human body.

Adult↗
PubMed1999

Needlestick and sharps injuries among health-care workers in Taiwan.

Sharps injuries are a major cause of transmission of hepatitis B and C viruses and human immunodeficiency virus in health-care workers. To determine the yearly incidence and causes of sharps injuries in health-care workers in Taiwan, we conducted a questionnaire survey in a total of 8645 health care workers, including physicians, nurses, laboratory technicians, and cleaners, from teaching hospitals of various sizes. The reported incidence of needlestick and other sharps injuries was 1.30 and 1.21 per person in the past 12 months, respectively. Of most recent episodes of needlestick/sharps injury, 52.0% were caused by ordinary syringe needles, usually in the patient units. The most frequently reported circumstances of needlestick were recapping of needles, and those of sharps injuries were opening of ampoules/vials. Of needles which stuck the health-care workers, 54.8% had been used in patients, 8.2% of whom were known to have hepatitis B or C, syphilis, or human immunodeficiency virus infection. Sharps injuries in health-care workers in Taiwan occur more frequently than generally thought and risks of contracting blood-borne infectious diseases as a result are very high.

Accidents, Occupational↗
PubMed1999

Prevalence of nonreporting behavior of sharps injuries in Taiwanese health care workers.

BACKGROUND: Health care workers (HCWs) were surveyed to identify factors associated with nonreporting behavior of sharps injuries (SIs) in Taiwan. METHODS: We surveyed 10,469 full-time medical, nursing, technical, and supporting personnel employed at 16 randomly selected hospitals from 132 available accredited teaching hospitals in Taiwan. Information about the most recent injury and reporting behavior after an SI were collected from July 1996 to June 1997 by using a pretested structured questionnaire. Eleven categories, including an open-ended option, were provided for participants to explain their nonreporting behavior. RESULTS: Questionnaires were completed by 82.6% (8645) of our sample, of whom 87.3% reported to have experienced a recent SI. A used item was the most commonly (P <. 001) involved item in an SI, and SIs with a used item were significantly more likely (odds ratio 3.6; CI 95%, 3.03-4.26; P <. 001) to be reported compared with an SI that involved unused items. A total of 81.8% of injuries were not reported, with job category significantly affecting reporting behavior (P <.001). Medical staff had the highest nonreporting rate (85.2%). Although attendees of a prevention program were statistically more likely (P <.001) to report an injury compared with nonattendees, the level of reporting in both groups was not encouraging (21.3% and 17.2%, respectively). All reasons given for nonreporting were disconcerting, but none more so than the use of subjective assessment of risk by 21.7% of HCWs who did not report their injuries. Other reasons for not reporting SIs included that the item was unused (34%) and that the HCW was too busy to report the SI (14.9%), unaware of reporting requirements (14. 4%), or immune to hepatitis B virus (12.4%). CONCLUSIONS: With 82% of SIs in Taiwanese HCWs going unreported, the expected national incidence will be seriously underestimated and impact the appropriateness of prevention programs. The very low rate of reporting suggests that the current reporting system requires simplification. Because most injuries involved used items, the reporting systems also should include a more responsive management component. The results also suggest that the current prevention programs, currently provided by the general nursing department, require expert content knowledge in infection control if nonreporting and SIs are to be reduced.

Humans↗
PubMed1999

Dermatoses in cement workers in southern Taiwan.

Construction workers are known to have occupational dermatoses. The prevalence of such dermatoses was unknown in Taiwanese construction workers. The objective of this study was to determine the work exposure, prevalence of skin manifestations, and sensitivity to common contact allergens in cement workers of southern Taiwan. A total of 1147 current regular cement workers were telephone-interviewed about skin problems during the past 12 months, work exposure, and personal protection. Among those interviewed, 166 were examined and patch tested with common contact allergens. A high % of cement workers reported skin problems in the past 12 months. More men (13.9%) reported skin problems possibly related to work than women (5.4%). Prevalence was associated with lower use of gloves, duration of work as cement worker, and more time in jobs involving direct manual handling of cement, especially tiling. A high % of dermatitis was noted in the 166 workers examined, which correlated with reported skin problems. On patch testing, construction workers had a high frequency of sensitivity to chromate. Sensitivity to chromate or cobalt was associated with reported skin problems, or dorsal hand dermatitis on examination. These workers' dermatitis was under-diagnosed and inadequately managed. It is concluded that cement workers in southern Taiwan had a high prevalence of skin problems related to cement use. Protective measures, work practice, and physician education should be improved to prevent or manage such problems.

Adult↗
PubMed1999

Resistance to TNF-alpha cytotoxicity can be achieved through different signaling pathways in rat mesangial cells.

We reported previously that Ro-318220 blocked expression of mitogen-activated protein kinase phosphatase-1 (MKP-1) induced by tumor necrosis factor-alpha (TNF-alpha) and subsequently caused apopotosis in mesangial cells (Y.-L. Guo, B. Kang, and J. R. Williamson. J. Biol. Chem. 273: 10362-10366, 1998). These data support our hypothesis that a TNF-alpha-inducible phosphatase may be responsible for preventing sustained activation of c-Jun NH2-terminal protein kinase (JNK) and consequent cell death in these cells (Y.-L. Guo, K. Baysal, B. Kang, L.-J. Yang, and J. R. Williamson. J. Biol. Chem. 273: 4027-4034, 1998). In this study, we investigated the involvement of protein kinase C (PKC) in regulation of MKP-1 expression in mesangial cells together with effects on viability. Although originally characterized as a PKC inhibitor, Ro-318220 inhibited TNF-alpha-induced MKP-1 expression through a mechanism other than blocking the PKC pathway. Furthermore, inhibition of the PKC pathway neither significantly affected TNF-alpha-induced MKP-1 expression nor made cells susceptible to toxic effect of TNF-alpha. Thus PKC activation is not essential for cells to achieve the resistance to TNF-alpha cytotoxicity displayed by normal mesangial cells. However, activation of PKC by phorbol 12-myristate 13-acetate (PMA) dramatically increased cellular resistance to the apoptotic effect of TNF-alpha. Coincidentally, PMA stimulated MKP-1 expression and suppressed JNK activation. Therefore, PMA-induced MKP-1 expression may contribute to the protective effect of PMA. These results provide a mechanistic explanation for previous documentation that PKC activation can rescue some cells from apopotosis.

Animals↗
PubMed1999

Tumor necrosis factor-alpha and ceramide induce cell death through different mechanisms in rat mesangial cells.

It has been proposed that ceramide acts as a cellular messenger to mediate tumor necrosis factor-alpha (TNF-alpha)-induced apoptosis. Based on this hypothesis, it was postulated that resistance of some cells to TNF-alpha cytotoxicity was due to an insufficient production of ceramide on stimulation by TNF-alpha. The present study was initiated to investigate whether this was the case in mesangial cells, which normally are insensitive to TNF-alpha-induced apoptosis. Our results indicate that although C2 ceramide was toxic to mesangial cells, the cell death it induced differed both morphologically and biochemically from that induced by TNF-alpha in the presence of cycloheximide (CHX). The most apparent effect of C2 ceramide was to cause cells to swell, followed by disruption of the cell membrane. It is evident that C2 ceramide caused cell death by necrosis, whereas TNF-alpha in the presence of CHX killed the cells by apoptosis. C2 ceramide did not mimic the effects of TNF-alpha on the activation of c-Jun NH2-terminal protein kinase and nuclear factor-kappaB transcription factor. Although mitogen-activated protein kinase [extracellular signal-related kinase (ERK)] was activated by both C2 ceramide and TNF-alpha, such activation appeared to be mediated by different mechanisms as judged from the kinetics of ERK activation. Furthermore, the cleavage of cytosolic phospholipase A2 during cell death induced by C2 ceramide and by TNF-alpha in the presence of CHX showed distinctive patterns. The present study provides evidence that apoptosis and necrosis use distinctive signaling machinery to cause cell death.

Animals↗