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Biomedical subjects

Y P Chen

Publications and source records attributed to Y P Chen.

At least 19 recordsLinked to original sources
PubMed2006

Immune pathways and defence mechanisms in honey bees Apis mellifera.

Social insects are able to mount both group-level and individual defences against pathogens. Here we focus on individual defences, by presenting a genome-wide analysis of immunity in a social insect, the honey bee Apis mellifera. We present honey bee models for each of four signalling pathways associated with immunity, identifying plausible orthologues for nearly all predicted pathway members. When compared to the sequenced Drosophila and Anopheles genomes, honey bees possess roughly one-third as many genes in 17 gene families implicated in insect immunity. We suggest that an implied reduction in immune flexibility in bees reflects either the strength of social barriers to disease, or a tendency for bees to be attacked by a limited set of highly coevolved pathogens.

Animals↗
PubMed2006

Prevalence and transmission of honeybee viruses.

Transmission mechanisms of six honeybee viruses, including acute bee paralysis virus (ABPV), black queen cell virus (BQCV), chronic bee paralysis virus (CBPV), deformed wing virus (DWV), Kashmir bee virus (KBV), and sacbrood bee virus (SBV), in honey bee colonies were investigated by reverse transcription-PCR (RT-PCR) methods. The virus status of individual queens was evaluated by examining the presence of viruses in the queens' feces and tissues, including hemolymph, gut, ovaries, spermatheca, head, and eviscerated body. Except for head tissue, all five tissues as well as queen feces were found to be positive for virus infections. When queens in bee colonies were identified as positive for BQCV, DWV, CBPV, KBV, and SBV, the same viruses were detected in their offspring, including eggs, larvae, and adult workers. On the other hand, when queens were found positive for only two viruses, BQCV and DWV, only these two viruses were detected in their offspring. The presence of viruses in the tissue of ovaries and the detection of the same viruses in queens' eggs and young larvae suggest vertical transmission of viruses from queens to offspring. To our knowledge, this is the first evidence of vertical transmission of viruses in honeybee colonies.

Animals↗
PubMed2006

[Preparation of monoclonal antibodies against West Nile virus envelope protein domain.].

BACKGROUND: To prepare monoclonal antibodies against West Nile virus (WNV) envelope protein domain. METHODS: BALB/c mice were immunized with recombinant antigen of West Nile virus envelope protein domain, and the spleen cells of the mice were used to prepare the monoclonal antibodies (McAb) by hybridoma technique. RESULTS: Three hybridoma cell strains secreting McAbs against WNV envelope protein domain, designated as 4F7, 6H3 and 8E4, respectively, were obtained and were identified by indirect enzyme linked immunosorbent assay (ELISA), they belonged to IgG1, IgG1 and Ig2a, respectively. Two epitopes of envelope protein domain were determined, among them, 4F7 and 6H3 were against the same epitope and 8E4 to another one. CONCLUSIONS: The results of indirect ELISA, Western blot and indirect immunofluorescence experiment indicated that these three McAbs were specific for West Nile virus envelope protein domain and did not cross-react with Japanese encephalitis virus and other viruses, so they can be used for specific detection of West Nile virus.

Animals↗
PubMed2005

Addition of clopidogrel to aspirin in 45,852 patients with acute myocardial infarction: randomised placebo-controlled trial.

BACKGROUND: Despite improvements in the emergency treatment of myocardial infarction (MI), early mortality and morbidity remain high. The antiplatelet agent clopidogrel adds to the benefit of aspirin in acute coronary syndromes without ST-segment elevation, but its effects in patients with ST-elevation MI were unclear. METHODS: 45,852 patients admitted to 1250 hospitals within 24 h of suspected acute MI onset were randomly allocated clopidogrel 75 mg daily (n=22,961) or matching placebo (n=22,891) in addition to aspirin 162 mg daily. 93% had ST-segment elevation or bundle branch block, and 7% had ST-segment depression. Treatment was to continue until discharge or up to 4 weeks in hospital (mean 15 days in survivors) and 93% of patients completed it. The two prespecified co-primary outcomes were: (1) the composite of death, reinfarction, or stroke; and (2) death from any cause during the scheduled treatment period. Comparisons were by intention to treat, and used the log-rank method. This trial is registered with ClinicalTrials.gov, number NCT00222573. FINDINGS: Allocation to clopidogrel produced a highly significant 9% (95% CI 3-14) proportional reduction in death, reinfarction, or stroke (2121 [9.2%] clopidogrel vs 2310 [10.1%] placebo; p=0.002), corresponding to nine (SE 3) fewer events per 1000 patients treated for about 2 weeks. There was also a significant 7% (1-13) proportional reduction in any death (1726 [7.5%] vs 1845 [8.1%]; p=0.03). These effects on death, reinfarction, and stroke seemed consistent across a wide range of patients and independent of other treatments being used. Considering all fatal, transfused, or cerebral bleeds together, no significant excess risk was noted with clopidogrel, either overall (134 [0.58%] vs 125 [0.55%]; p=0.59), or in patients aged older than 70 years or in those given fibrinolytic therapy. INTERPRETATION: In a wide range of patients with acute MI, adding clopidogrel 75 mg daily to aspirin and other standard treatments (such as fibrinolytic therapy) safely reduces mortality and major vascular events in hospital, and should be considered routinely.

Aged↗
PubMed2005

Early intravenous then oral metoprolol in 45,852 patients with acute myocardial infarction: randomised placebo-controlled trial.

BACKGROUND: Despite previous randomised trials of early beta-blocker therapy in the emergency treatment of myocardial infarction (MI), uncertainty has persisted about the value of adding it to current standard interventions (eg, aspirin and fibrinolytic therapy), and the balance of potential benefits and hazards is still unclear in high-risk patients. METHODS: 45,852 patients admitted to 1250 hospitals within 24 h of suspected acute MI onset were randomly allocated metoprolol (up to 15 mg intravenous then 200 mg oral daily; n=22,929) or matching placebo (n=22,923). 93% had ST-segment elevation or bundle branch block, and 7% had ST-segment depression. Treatment was to continue until discharge or up to 4 weeks in hospital (mean 15 days in survivors) and 89% completed it. The two prespecified co-primary outcomes were: (1) composite of death, reinfarction, or cardiac arrest; and (2) death from any cause during the scheduled treatment period. Comparisons were by intention to treat, and used the log-rank method. This study is registered with ClinicalTrials.gov, number NCT 00222573. FINDINGS: Neither of the co-primary outcomes was significantly reduced by allocation to metoprolol. For death, reinfarction, or cardiac arrest, 2166 (9.4%) patients allocated metoprolol had at least one such event compared with 2261 (9.9%) allocated placebo (odds ratio [OR] 0.96, 95% CI 0.90-1.01; p=0.1). For death alone, there were 1774 (7.7%) deaths in the metoprolol group versus 1797 (7.8%) in the placebo group (OR 0.99, 0.92-1.05; p=0.69). Allocation to metoprolol was associated with five fewer people having reinfarction (464 [2.0%] metoprolol vs 568 [2.5%] placebo; OR 0.82, 0.72-0.92; p=0.001) and five fewer having ventricular fibrillation (581 [2.5%] vs 698 [3.0%]; OR 0.83, 0.75-0.93; p=0.001) per 1000 treated. Overall, these reductions were counterbalanced by 11 more per 1000 developing cardiogenic shock (1141 [5.0%] vs 885 [3.9%]; OR 1.30, 1.19-1.41; p<0.00001). This excess of cardiogenic shock was mainly during days 0-1 after admission, whereas the reductions in reinfarction and ventricular fibrillation emerged more gradually. Consequently, the overall effect on death, reinfarction, arrest, or shock was significantly adverse during days 0-1 and significantly beneficial thereafter. There was substantial net hazard in haemodynamically unstable patients, and moderate net benefit in those who were relatively stable (particularly after days 0-1). INTERPRETATION: The use of early beta-blocker therapy in acute MI reduces the risks of reinfarction and ventricular fibrillation, but increases the risk of cardiogenic shock, especially during the first day or so after admission. Consequently, it might generally be prudent to consider starting beta-blocker therapy in hospital only when the haemodynamic condition after MI has stabilised.

Administration, Oral↗
PubMed2005

Quantitative real-time reverse transcription-PCR analysis of deformed wing virus infection in the honeybee (Apis mellifera L.).

Deformed wing virus (DWV) can cause wing deformity and premature death in adult honeybees, although like many other bee viruses, DWV generally persists as a latent infection with no apparent symptoms. Using reverse transcription (RT)-PCR and Southern hybridization, we detected DWV in all life stages of honeybees, including adults with and without deformed wings. We also found DWV in the parasitic mite Varroa destructor, suggesting that this mite may be involved in the transmission of DWV. However, the detection of the virus in life stages not normally associated with mite parasitism (i.e., eggs and larvae) suggests that there are other modes of transmission. The levels of DWV in different life stages of bees were investigated by using TaqMan real-time quantitative RT-PCR. The amounts of virus varied significantly in these different stages, and the highest levels occurred in pupae and in adult worker bees with deformed wings. The variability in virus titer may reflect the different abilities of bees to resist DWV infection and replication. The epidemiology of DWV is discussed, and factors such as mite infestation, malnutrition, and climate are also considered.

Animals↗
PubMed2003

Quantitation of a Glyptapanteles indiensis polydnavirus gene expressed in parasitized host, Lymantria dispar, by real-time quantitative RT-PCR.

Glyptapanteles indiensis is a polydnavirus-carrying wasp that parasitizes early instar gypsy moth larvae. During oviposition, the wasp injects calyx fluid containing polydnavirus along with its eggs into the host. Within the host, expression of polydnavirus genes triggers a set of changes in host physiology, which are of critical importance for the survival of the wasp. In the present study, a G. indiensis polydnavirus (GiPDV) gene, represented by cDNA clone GiPDV 1.1, was selected for expression analysis in the parasitized host. The GiPDV 1.1 gene transcript was detected in host hemolymph 30 min post-parasitization (pp) and continued to be detected for six days. The level of GiPDV 1.1 expression varied in different host tissues and expression in the brain was lower than in the hemolymph. The findings suggest that GiPDV 1.1 could be involved in early protection of parasitoid eggs from host cellular encapsulation. The temporal and spatial variations in PDV gene expression in different host tissues post-parasitization affirm their specific host regulation mechanism.

Amino Acid Sequence↗
PubMed2003

Quantitative expression analysis of a Glyptapanteles indiensis polydnavirus protein tyrosine phosphatase gene in its natural lepidopteran host, Lymantria dispar.

In the present study, expression of a newly identified Glyptapanteles indiensis polydnavirus (GiPDV) gene encoding a putative protein tyrosine phosphatase (PDVPTP) was monitored in vivo in the parasitized host, L. dispar, using one step RT-PCR. Expression levels of the PDVPTP transcript were also evaluated in various host tissues at different times post parasitization (pp) using RT quantitative competitive PCR (RT-qcPCR). Expression levels varied, with the most abundant transcript detected in host haemolymph 2 h pp. The high expression level in host haemolymph at an early stage of parasitization suggested a potential role for viral PDVPTP in disruption of the host immune system and protection of the endoparasitoid egg from encapsulation. Additionally, the PDVPTP gene or its homolog(s) mapped to more than one GiPDV genomic DNA segment, which may account for its increased level of expression in the absence of virus replication.

Animals↗
PubMed2003

Morphological and genomic characterization of the polydnavirus associated with the parasitoid wasp Glyptapanteles indiensis (Hymenoptera: Braconidae).

Glyptapanteles indiensis polydnavirus (GiPDV) is essential for successful parasitization of the larval stage of the lepidopteran Lymantria dispar (gypsy moth) by the endoparasitic wasp Glyptapanteles indiensis. This virus has not been characterized previously. Ultrastructural studies of GiPDV showed that virions had a rod-like or rectangular form and each contained as many as ten nucleocapsids enclosed by a single unit membrane envelope. Field inversion gel electrophoresis (FIGE) analysis of the virus genomic DNA revealed that GiPDV had a segmented genome composed of 13 dsDNA segments, ranging in size from approximately 11 kb to more than 30 kb. Four genomic segments were present in higher molar concentration than the others. Further characterization of the GiPDV genome yielded several cDNA clones which derived from GiPDV-specific mRNAs, and Northern blot analysis confirmed expression of isolated cDNA clones in the parasitized host. Each was present on more than one GiPDV genomic DNA segment, suggesting the existence of related sequences among DNA segments. It has been proposed previously that in polydnavirus systems, genome segmentation, hypermolar ratio segments and segment nesting may function to increase the copy number of essential genes and to increase the levels of gene expression in the absence of virus replication. The present data support this notion and suggest that GiPDV morphology and genomic organization may be intrinsically linked to the function and evolutionary strategies of the virus.

Amino Acid Sequence↗
PubMed2003

Coagulation of humic-kaolin-PACI aggregates.

Water treatment residual flocs are fractal-like aggregates made of many initial aggregates. We investigated in this study the coagulation dynamics for the humic-mineral-polyaluminium chloride (PACI) aggregates using small-angle light scattering techniques and the free-settling test. In contrast to reports in the literature, the presence of humic acid did not lead to a loose floc. Not only the time evolution of the coagulation dynamics, but also the final floc characteristics are only mildly affected by the humic acid. However, the strength of the formed floc does decline with humic acid, which leads to a turbid supernatant with high level of organics.

Aluminum Hydroxide↗
PubMed2002

Patients with generalized social phobia direct their attention away from faces.

The experiment tested whether patients with social phobia direct their attention to or away from faces with a range of emotional expressions. A modified dot probe paradigm (J. Abnorm. Psychol. 95 (1986) 15) measured whether participants attended more to faces or to household objects. Twenty patients with social phobia were faster in identifying the probe when it occurred in the location of the household objects, regardless of whether the facial expressions were positive, neutral, or negative. In contrast, controls did not exhibit an attentional preference. The results are in line with recent theories of social phobia that emphasize the role of reduced processing of external social cues in maintaining social anxiety.

Adult↗
PubMed2001

[Effects of katamine on cardiopulmonary bypass-induced interleukin-6 and interleukin-8 response and its significance].

OBJECTIVE: To investigate the effects of ketamine on cardiopulmonary bypass-induced IL-6 and IL-8 response. METHODS: Twenty-four adult patients undergoing cardiac valve replacement were divided into control and ketamine group (n = 12). In the ketamine group, 1 mg.kg-1 ketamine was infused intravenously at the beginning of operation and CBP. Plasma levenof IL-6 and IL-8 were measured at different time after induction of anesthesia. RESULTS: In both groups, the levels of IL-6 and IL-8 increased significantly compared with those at the time before CBP (P < 0.05), but compared with those in control groups, IL-6 and IL-8 levels decreased obviously in ketamine group(P < 0.05). CONCLUSIONS: Ketamine is effective to reduce cardiopulmonary bypass-induces IL-6 and IL-8 response and protect reperfusion myocardium.

Adult↗
PubMed2001

[Study on expression of PCNA and estrogen, progesterone receptors in endometrial carcinoma].

OBJECTIVE: To investigate the proliferating ability of tumor cells in 74 cases with endometrial carcinoma (EMC), as well as define the correlation between clinical pathology, prognostic features and estrogen receptor (ER), progesterone receptor (PR). METHODS: Proliferating cell nucleus antigen (PCNA) and ER/PR content were examined using immunohistochemical assay. RESULTS: PCNA was expressed in both benign hyperplasia and EMC, but positive rate in the latter was significantly higher than that in the former (82.4% vs 30.0%) (P < 0.01). EMC well differentiated had lower proliferating index (PI) score than those moderately and poorly differentiated(P < 0.001), and the PI score was negatively related to the grade of differentiation(r = -0.52, P < 0.01). PI score in early cases (I/II) was significantly lower than that in advanced ones(III/IV) (P < 0.05), and the PI score was positively related to the clinical stages (r = 0.55, P < 0.01). Positive rates of ER, PR were 66.2% (49/74) and 75.7%(56/74) respectively, expression of PCNA was negatively related with ER and PR(r = -0.42, -0.51, respectively, P < 0.05). CONCLUSIONS: EMC cells with poorer differentiation or in more advanced stages have faster proliferating ability and aggressive biological behavior. Expression of PCNA combined with detection of ER/PR not only apts to retrospective study, but also has some prognostic value.

Adult↗
PubMed2001

Prevention of autoimmunity by induction of cutaneous tolerance.

Autoimmune gastritis develops in 20-60% of BALB/c mice following thymectomy at 3 days after birth (3dnTx). Previously we identified the gastric H+/K+ ATPase as the causative autoantigen and mapped the immunoreactive T cell epitope to a carboxyl-terminal peptide on the gastric H+/K+ ATPase beta subunit. Here we show that autoimmune gastritis can be suppressed by immunizing 3dnTx mice through neonatal skin with the beta subunit peptide, in combination with the contact sensitizer TNCB. When spleen cells were transferred from suppressed mice to nude mice a proportion of recipient mice developed gastritis. These results indicate that pathogenic T cells were still present in the 3dnTx mice but the absence of gastritis indicates that their activity can be regulated following induction of cutaneous tolerance by immunizing through neonatal skin. We propose that cutaneous tolerance is induced through mediation of immature Langerhans cells in neonatal skin and that this tolerance prevented the autoreactivity of pathogenic T cells. This procedure will have implications for strategies to suppress autoimmunity.

Amino Acid Sequence↗
PubMed2001

Presence of Epstein-Barr virus latent membrane protein 1 gene in the nasopharyngeal swabs from patients with nasopharyngeal carcinoma.

BACKGROUND: Nasopharyngeal carcinoma (NPC) is the most common head and neck malignancy in southeastern China and Taiwan. Early detection of the local disease followed immediately by proper treatment is essential to increase the cure and survival rates. Because every NPC tumor cell carries Epstein-Barr Virus (EBV) genomes, detection of EBV genomic DNA such as latent membrane protein 1 gene (LMP1) might indicate the presence of NPC. We developed a simple and noninvasive technique of nasopharyngeal swabbing to acquire nasopharyngeal cells for detecting the presence of EBV genome. The aim of this study was to investigate the feasibility and reliability of this technique. METHODS: We collected nasopharyngeal cells by means of a nasopharyngeal swabbing technique and detected the presence of EBV LMP1 with polymerase chain reaction (PCR). Thirty-eight swab specimens were obtained from patients with NPC who were newly diagnosed or were just beginning radiotherapy. Two groups of control subjects were recruited, including 20 patients with other head and neck cancers and eight family members of the NPC patients. An additional group of 65 NPC patients were enrolled in the course of regular follow-up after definitive radiotherapy. RESULTS: All of the samples yielded sufficient DNA for PCR amplification. Thirty-six of 38 NPC swab samples were positive for EBV LMP1, and all the control subjects had swab sample results negative for EBV. All five patients with suspected local recurrence exhibited positive EBV test results. CONCLUSIONS: Demonstration of EBV LMP1 in the nasopharyngeal swab specimens detected NPC with a sensitivity of 94.7% and specificity of 100%. This study confirms the reliability and feasibility of nasopharyngeal swab in the predicting and screening of NPC.

Base Sequence↗