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Biomedical subjects

Y Chang

Publications and source records attributed to Y Chang.

At least 163 records · Page 9Linked to original sources
PubMed1998

Impact of varying stages of endometriosis on the outcome of in vitro fertilization-embryo transfer.

PURPOSE: The impact of severity of endometriosis on the outcome of in vitro fertilization (IVF) was analyzed in an uncontrolled, retrospective study in an academic IVF program. METHODS: Sixty-one patients with a primary diagnosis of endometriosis undergoing 85 cycles of IVF were included in the study. Patients were divided according to the severity of disease based on the revised American Fertility Society (AFS) classification into groups A (stages I/II, or minimal/ mild) and B (stages III/IV, or moderate/severe). Group A included 32 patients undergoing 45 IVF-embryo transfer (ET) cycles; group B included 29 patients undergoing 40 IVF cycles. Exclusion criteria were age older than 40 years, basal day 3 follicle stimulating hormone (FSH) greater than 20 IU/L, male-factor infertility, assisted hatching, and gamete intrafallopian transfer cases. Stimulation for IVF cycles was standard using pituitary down-regulation with gonadotropin-releasing hormone agonist in a midluteal protocol. Controlled ovarian hyperstimulation (COH) was achieved using a combination of FSH and human menopausal gonadotropin. Outcomes assessed included response to COH and number, maturity, and quality of oocytes retrieved. Fertilization, implantation, and pregnancy rates after IVF-ET were also analyzed. RESULTS: The response to COH and the number, maturity, and quality of the oocytes was comparable between patients with varying severity of endometriosis. Fertilization rates for oocytes of patients in group B (stages III/IV) were significantly impaired compared to those in group A (stages I/II) (P = 0.004). The rates for implantation, clinical pregnancy, and miscarriage were comparable between the two groups. CONCLUSIONS: The reduced fertilization potential of the oocytes obtained from patients with severe endometriosis in the absence of male-factor infertility suggests an adverse biological impact of the advanced disease on the oocytes. The outcome of IVF-ET, however, is unaffected by increasing severity of endometriosis. This suggests that IVF may compensate for or overcome this reduction in the biological potential of the oocytes associated with severe disease, thus accounting for a comparable outcome irrespective of the severity of endometriosis.

Adult↗
PubMed1998

Kaposi's sarcoma-associated herpesvirus-encoded oncogenes and oncogenesis.

Molecular biologic studies of Kaposi's sarcoma-associated herpesvirus (KSHV) have identified a number of potential viral oncogenes that may contribute to KSHV-related neoplasia including a D-type cyclin, an IL-6-like cytokine, and a novel member of the interferon regulatory factor family. KSHV is functionally related to other DNA tumor viruses by encoding specific proteins to inhibit pRb, pro-apoptotic, and interferon-signaling tumor suppressor pathways. The virus appears to employ molecular piracy of cellular regulatory genes as a mechanism to avoid cellular antiviral responses. The transparency of the KSHV genome allows ready identification of the cellular regulatory pathways which may be involved in transformation by KSHV. This provides strong support to the notion that some tumor suppressor pathways serve the dual function of being antiviral pathways to induce cell cycle arrest, apoptosis, and enhanced cell-mediated immunity in response to virus infection. Neoplasia may result from specific viral strategies to overcome these host defense pathways.

Genome, Viral↗
PubMed1998

Characterization of kringle domains of angiostatin as antagonists of endothelial cell migration, an important process in angiogenesis.

Angiogenesis is a complex process that involves endothelial cell proliferation, migration, basement membrane degradation, and neovessel organization. Angiostatin, consisting of four homologous triple-disulfide bridged kringle domains, has previously been shown to exhibit profound inhibition of endothelial cell proliferation in vitro and angiogenesis in vivo. It was also demonstrated that angiostatin could suppress the growth of a variety of tumors via the blocking of angiogenesis. The primary aim of our study was to characterize the kringle domains of angiostatin for their inhibitory activities of endothelial cell migration in order to elucidate their contributions to the anti-angiogenic function of angiostatin. In this report, we demonstrate for the first time that the kringles of angiostatin play different roles in inhibiting endothelial cell migration, a crucial process in angiogenesis. Kringle 4, which has only marginal anti-proliferative activity, is among the most potent fragments in inhibiting endothelial cell migration (IC50 of approximately 500 nM). In contrast, kringle 1-3, which is equivalent to angiostatin in inhibiting endothelial cell proliferation, manifests only a modest anti-migratory effect. The combination of kringle 1-3 and kringle 4 results in an anti-migratory activity comparable to that of angiostatin. When kringle 1 is removed from kringle 1-3, the resulting kringle 2-3 becomes more potent than kringle 1-3. This implies that kringle 1, although virtually ineffective in inhibiting endothelial cell migration, may influence the conformation of kringle 1-3 to alter its anti-migratory activity. We also show that disruption of the kringle structure by reducing/alkylating agents markedly attenuates the anti-migratory activity of angiostatin, demonstrating the significance of kringle conformation in maintaining the anti-angiogenic activity of angiostatin. Our data suggest that different kringle domains may contribute to the overall anti-angiogenic function of angiostatin by their distinct anti-migratory activities.

Adrenal Glands↗
PubMed1998

Substitutions of the highly conserved M2 leucine create spontaneously opening rho1 gamma-aminobutyric acid receptors.

All members of the receptor-operated ion channel family that includes gamma-aminobutyric acid (GABA), glycine, nicotinic acetylcholine, and serotonin type 3 receptors have a conserved leucine near the center of the presumed second membrane-spanning domain. This leucine has been postulated to play a role in the gating of the pore. In this study, we examined the effects of mutating this leucine (L301) on the function of human homomeric rho1 GABA receptors. Oocytes expressing rho1 GABA receptors in which this leucine was substituted with alanine (A), glycine (G), serine (S), threonine (T), valine, or tyrosine, but not isoleucine or phenylalanine, demonstrated larger-than-normal resting conductances in the absence of GABA. This resting conductance had a reversal potential (and shifted reversal potential with chloride substitution) indistinguishable from that of the wild-type rho1 GABA-activated current. This resting conductance was antagonized by picrotoxin and, in the case of the A, G, S, and T substitutions, by GABA itself. Although the rho1 competitive antagonist 3-aminopropyl(methyl)-phosphinic acid did not block the resting conductance, this compound did competitively inhibit the GABA-mediated antagonism of the resting conductance. At higher concentrations, both 3-aminopropyl(methyl)-phosphinic acid and GABA directly activated the A, G, S, and T mutant receptors. Taken together, these data suggest that substitution of this highly conserved leucine with either small or polar residues produced rho1 GABA receptors that can open in the absence of GABA and support the hypothesis that this leucine may play a key role in the gating of the pore.

Animals↗
PubMed1998

Transcription mapping of the Kaposi's sarcoma-associated herpesvirus (human herpesvirus 8) genome in a body cavity-based lymphoma cell line (BC-1).

Kaposi's sarcoma-associated herpesvirus (KSHV) gene transcription in the BC-1 cell line (KSHV and Epstein-Barr virus coinfected) was examined by using Northern analysis with DNA probes extending across the viral genome except for a 3-kb unclonable rightmost region. Three broad classes of viral gene transcription have been identified. Class I genes, such as those encoding the v-cyclin, latency-associated nuclear antigen, and v-FLIP, are constitutively transcribed under standard growth conditions, are unaffected by tetradecanoylphorbol acetate (TPA) induction, and presumably represent latent viral transcripts. Class II genes are primarily clustered in nonconserved regions of the genome and include small polyadenylated RNAs (T0.7 and T1.1) as well as most of the virus-encoded cytokines and signal transduction genes. Class II genes are transcribed without TPA treatment but are induced to higher transcription levels by TPA treatment. Class III genes are primarily structural and replication genes that are transcribed only following TPA treatment and are presumably responsible for lytic virion production. These results indicate that BC-1 cells have detectable transcription of a number of KSHV genes, particularly nonconserved genes involved in cellular signal transduction and regulation, during noninduced (latent) virus culture.

Genes, Viral↗
PubMed1998

Characterization of responses to neurokinin A in the isolated perfused guinea pig heart.

Goals of this study were to identify and characterize effects of neurokinin A (NKA) in isolated guinea pig hearts. Bradycardia, augmentation of ventricular contractions, and reduction of perfusion pressure were prominent responses to bolus injections of NKA (0. 25-25 nmol). NKA was more potent than substance P (SP) in causing bradycardia but did not differ in potency for lowering perfusion pressure. Doses of SP of 25 nmol or less decreased ventricular force, whereas 100 nmol caused a biphasic response. The percent decrease in heart rate produced by 25 nmol NKA was reduced from 58.0 +/- 4.8 to 39.6 +/- 3.5% in the presence of 1 microM atropine (n = 5). The positive inotropic response to 25 nmol of NKA in spontaneously beating hearts was replaced by a negative inotropic response during pacing (22.5 +/- 3.3% increase vs. 11.7 +/- 1.7% decrease, n = 5). Reserpine pretreatment did not affect the positive inotropic response to NKA. Specific binding sites for 125I-labeled NKA were localized to intracardiac ganglia and coronary arteries but not to myocardium. It was concluded that 1) negative chronotropic responses to NKA involve cholinergic and noncholinergic mechanisms, and 2) the positive inotropic response is an indirect action.

Animals↗
PubMed1998

Expression of the glycoprotein E2 of the classical swine fever virus in Escherichia coli.

The glycoprotein E2 sequences of classical swine fever virus (strain p97) were cloned, sequenced and expressed in E. coli. Result from SDS-polyacrylamide gel electrophoresis analysis of expressed proteins revealed the presence of a prominently stained band corresponding to a molecular mass of 61 kDa, which is in agreement with the predicted size from the DNA sequence. The recombinant E2 protein contained an aminoterminal tag of six histidines that could be used for purification by the nickel chelate affinity chromatography. The elution fractions of the expressed protein also contain additional bands of 40 and 35 kDa proteins, indicating proteolytic cleavages might occur. Our Western blotting result also supported that the expression of the recombinant E2 protein of the classical swine fever virus were accomplished.

Animals↗
PubMed1998

Sonographic appearance of benign and malignant conditions of the colon.

OBJECTIVE: The objective of this study was to compare the sonographic appearance of different abnormalities of the colon to evaluate the role of sonography in their differential diagnosis. MATERIALS AND METHODS: We retrospectively reviewed videotaped sonographic examinations of 99 patients with proven diagnoses that included diverticulitis (n = 35), malignancy (n = 20), Crohn's disease (n = 16), pseudomembranous colitis (n = 14), ischemic colitis (n = 9), and ulcerative colitis (n = 5). Data were collected with regard to gut features, including the site of colonic involvement, associated small-bowel involvement, length of diseased segment, stratification, luminal contents, pneumatosis, and diverticula. Perigut features evaluated included abnormal fat, abscess, fistula, and ascites. RESULTS: On sonography, the following features were statistically significant (p < .05). Involvement of the small bowel was more common in patients with Crohn's disease than in the remainder of the study population (44% versus 1%). Left-sided colonic disease (91% versus 38%), diverticula (91% versus 3%), and perigut findings (91% versus 57%), including abnormal fat (83% versus 39%) and abscess (34% versus 8%), were features that indicated diverticulitis. Malignant conditions were more common in patients with a greater wall thickness (mean, 26.2 mm versus 10.2 mm), asymmetric involvement (85% versus 39%), loss of stratification (85% versus 20%), absence of perigut findings (65% versus 22%), and involvement of a short diseased segment (70% versus 16%). Involvement of the entire colon (50% versus 2%), luminal contents (64% versus 28%), and ascites (64% versus 26%) were features suggesting pseudomembranous colitis. CONCLUSION: Although the sonographic appearances of abnormalities of the colon overlap, some sonographic features are helpful in the differential diagnosis of colonic abnormalities.

Adult↗
PubMed1998

[Clinical study of fructose 1,6-diphosphate on myocardial ischemia/reperfusion injuries].

Twenty ventricular septal defect patients who underwent cardiopulmonary bypass (CPB) were divided into 1,6-diphosphate group and controlled group (10 cases each). Blood samples were taken at pre- and post-cardiopulmonary bypass 30 min, 6 h, and 24 h to determine lactate dehydrogenase enzyme(LDH), creatine kinase enzyme(CK) and its isoenzyme(CK-MB) levels. We found that 1,6-diphosphate decreased the increasing levels of LDH, CK, and CK-MB after cardiopulmonary bypass. It is suggested that 1,6-diphosphate may attenuate myocardial ischemia/reperfusion injuries during cardiopulmonary bypass.

Cardioplegic Solutions↗
PubMed1998

[Influence of isoflurane and sevoflurane on metabolism of oxygen free radicals in cardiac valve replacement].

To investigate effects of isoflurane and sevoflurane on the levels of lipid peroxides (LPO) in plasma and superoxide dismutase (SOD) in red blood cells during myocardial ischemia/reperfusion, and to study myocardial protection of these two volatile anesthetcs, 30 patients undergoing cardiac valve replacement were randomly divided into isoflurane (Group I), sevoflurane (Group S), and controlled group (Group C). Patients of Group I were anesthetized with isoflurane mainly, Group S with sevoflurane, and Group C with fentanyl. LPO and SOD levels were measured at five points before and during the operation. The results were as follows: SOD levels in all groups did not change significantly. LPO levels in Group C increased during the operation, while in other two groups didn't. Rates of automatical rebeating of hearts in Group C were lower than that of hearts in other two groups. It is suggested that isoflurane and sevoflurane can inhibit increasing of LPO levels to attenuate myocardial ischemia/reperfusion injuries mediated by oxygen free radicals during open-heart surgery.

Adult↗
PubMed1998

Stress-reducing effect of physician's tape-recorded support on cardiac surgical patients in the intensive care unit.

Staying in an intensive care unit (ICU) is very stressful for patients after heart surgery. Although it is a general belief that support from doctors is important to reduce patients' tension, no quantitative data are available. We investigated the stress-reducing effects of a tape-recorded message from the physician which provided information regarding the surgery and emotional support for heart surgery patients postoperatively in the ICU. Sixty patients who underwent cardiac surgery were randomly allocated to two equal groups. The patients in the experimental group listened to a tape-recorded message from their attending surgeon soon after they recovered from anesthesia, while the control group rested during the study period. The effectiveness of the tape-recorded support program was evaluated by the influence on heart rate, blood pressure, and finger skin temperature, as well as the degree of subjective pain, tension, anxiety, depression, and anger. The pain and tension levels of the patients were measured using a visual analogue scale, while the severity of anxiety, depression, and anger was evaluated using the Brief Symptom Rating Scale. Patients' evaluation of the usefulness of the program was also assessed. After listening to the physician's recorded message, the mean increase in the skin finger temperature in the experimental group was higher than in the control group (0.44 degree C vs 0.25 degree C, p = 0.0513). The experimental group had significant decreases in their mean scores of pain (-1.11 vs 0.36, p = 0.0043), tension (-2.26 vs -0.25, p = 0.0001), anxiety (-1.3 vs -0.57, p = 0.0473), and depression (-2.24 vs -0.37, p = 0.0253). The patients showed a high need for this support program (mean need score 8.4). These findings show that a physician's tape-recorded message providing information and emotional support can reduce stress in heart surgery patients in the ICU postoperatively.

Cardiac Surgical Procedures↗
PubMed1998

Computed tomography in the determination of surgical emergency for symptomatic abdominal aortic aneurysm.

BACKGROUND: What is the best surgical timing for symptomatic AAA? Surely, the answer depends on accurate and prompt diagnosis of 'rupture or not'. Abdominal CT is one of the reliable and familiar diagnostic tools. We will present our own CT classification method for symptomatic AAA which is used as the guideline for 'emergency or not'. METHODS: From January 1989 to January 1995, 52 patients with symptomatic AAA received diagnostic CT scan for quick disease differentiation and determination of surgical emergency. The findings were classified into four categories. Category I included 26 patients with intact aorta; Category II included four patients with contained retroperitoneal abdominal aortic leakage; Category III included 14 patients with contained massive retroperitoneal hematoma; and Category IV included eight patients with retroperitoneal or intraperitoneal active bleeding. RESULTS: Compared with the standard diagnosis of rupture via laparotomy, CT is an excellent tool, showing 88% sensitivity and 88% specificity. This is better than sonography, which has a high false-positive rate of 33% and low specificity of 62%. Hospital mortality was distinctive with 4.3% in Category I, none in Category II, 25% in Category III and 87.5% in Category IV. CONCLUSIONS: In our experience, CT scan is a better diagnostic tool than sonography for symptomatic AAA. Even the delay imposed by obtaining a preoperative CT scan in patients with possible ruptured aneurysm does not adversely affect the patient's outcome. The information obtained significantly aids not only preoperative but also intraoperative management.

Aged↗
PubMed1998

Detection of transcripts initiated from two viral promoters (Cp and Wp) in Epstein-Barr virus-infected nasopharyngeal carcinoma cells and biopsies.

Different activation of Epstein-Barr virus (EBV) promoters results in distinct expression patterns of EBV nuclear antigens (EBNAs) and may further decide the role of EBV in the cellular pathogenesis. In EBV-associated nasopharyngeal carcinoma (NPC) biopsies, it has generally been believed that Q promoter (Qp)-initiated EBNA1 is the only EBNA gene to be expressed and that the other two viral promoters, Cp and Wp, which can lead to expression of EBNA1-6, are inactive. However, the failure to demonstrate the activities of Cp and Wp may have been due to the limited sensitivities of detection approaches used. In the present article, the EBV promoter usage and gene expression were re-examined in both EBV-infected NPC cells in vitro and NPC biopsies in vivo. An NPC cell line susceptible to EBV infection in vitro was established by transfection with a plasmid expressing a well-known EBV receptor, CR2. The presence of viral DNA and EBNA proteins was demonstrated in these EBV-infected cells using PCR and anticomplement immunofluorescence assay, respectively. As has been identified in NPC biopsies, viral transcripts of Qp-initiated EBNA1, latent membrane protein (LMP)1, LMP2A, LMP2B, and BamHI A genes, as well as the EBV-encoded small RNA (EBER)1 were detected in these in vitro-infected cells using reverse-transcription-PCR. Notably, viral transcripts initiated from Cp or Wp were also found in the infected cells. Furthermore, Cp- or Wp-initiated transcripts and EBNA2 mRNA were detected in some NPC biopsies. Taking advantage of this sensitive detection approach, our observation that Cp and Wp may be active in NPC cells raises the possibility that EBNA2 to 6, in addition to EBNA1, may play roles in the pathogenesis of NPC.

Adult↗
PubMed1998

Malignant fibrous histocytoma of the heart presenting as right ventricular outflow tract obstruction: a case report.

Primary malignant fibrous histocytoma (MFH) of the heart is extremely rare. Herein, we report the case of a 17-year-old woman with a primary MFH in the right ventricular outflow tract, presenting with increasing dyspnea on exertion. Wide excision of the tumor, including part of the pulmonary artery and pulmonary valve, was performed under cardiopulmonary bypass. Her postoperative recovery was uneventful.

Adolescent↗
PubMed1998

Epidural anesthesia combined with propofol sedation for abdominal hysterectomy in a patient with amyotrophic lateral sclerosis--a case report.

Amyotrophic lateral sclerosis (ALS) is a disease characterized by progressive degeneration of the lower motor neurons, motor nuclei of the brain stem, and the descending pathway of the upper motor neurons. As the disease progresses, atrophy and weakness involve most of the skeletal muscles, including those of the tongue, pharynx larynx and chest. Impairment of respiration, altered response to muscle relaxants, and predisposition of aspiration affect a safe anesthetic management. General anesthesia with tracheal intubation might ensure intraoperative ventilatory management, but it could also increase the risk of aspiration with its entailing airway obstruction and demand the need of postoperative artificial ventilatory support. In this report, we described the use of epidural analgesia with 2% lidocaine combined with continuous infusion of low dose propofol for sedation for a ALS patient undergoing abdominal hysterectomy. The anesthetic management of this patient was smooth and successful. Besides, epidural morphine could provide excellent postoperative pain relief without respiratory complications.

Amyotrophic Lateral Sclerosis↗
PubMed1997

KSHV ORF K9 (vIRF) is an oncogene which inhibits the interferon signaling pathway.

Kaposi's sarcoma-associated herpesvirus (KSHV) is a gammaherpesvirus linked to the development of Kaposi's sarcoma and a rare B cell lymphoma, primary effusion lymphoma. The KSHV gene ORF K9 encodes vIRF which is a protein with low but significant homology to members of the interferon (IFN) regulatory factor (IRF) family responsible for regulating intracellular interferon signal transduction (Moore PS, Boshoff C, Weiss RA and Chang Y. (1996). Science, 274, 1739-1744). vIRF inhibits IFN-beta signal transduction as measured using an IFN-responsive ISG54 reporter construct co-transfected with ORF K9 into HeLa and 293 cells. vIRF also suppresses genes under IFN regulatory control as shown by inhibition of the IFN-beta inducibility of p21WAF1/CIP1, however, no direct DNA-binding or protein-protein interactions characteristic for IRF repressor proteins were identified. Stable transfectant NIH3T3 clones expressing vIRF grew in soft agar and at low serum concentrations, lost contact inhibition and formed tumors after injection into nude mice indicating that vIRF has the properties of a viral oncogene. Since vIRF is primarily expressed in KSHV-infected B cells, not KS spindle cells, this study suggests that vIRF is a transforming oncogene active in B cell neoplasias that may provide a unique immune escape mechanism for infected cells. This data is consistent with tumor suppressor pathways serving a dual function as host cell antiviral pathways.

3T3 Cells↗
PubMed1997

Angiogenic and HIV-inhibitory functions of KSHV-encoded chemokines.

Unique among known human herpesviruses, Kaposi's sarcoma-associated herpesvirus (KSHV or HHV-8) encodes chemokine-like proteins (vMIP-I and vMIP-II). vMIP-II was shown to block infection of human immunodeficiency virus-type 1 (HIV-1) on a CD4-positive cell line expressing CCR3 and to a lesser extent on one expressing CCR5, whereas both vMIP-I and vMIP-II partially inhibited HIV infection of peripheral blood mononuclear cells. Like eotaxin, vMIP-II activated and chemoattracted human eosinophils by way of CCR3. vMIP-I and vMIP-II, but not cellular MIP-1alpha or RANTES, were highly angiogenic in the chorioallantoic assay, suggesting a possible pathogenic role in Kaposi's sarcoma.

Animals↗