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T C Wu

Publications and source records attributed to T C Wu.

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

Enhancement of DNA vaccine potency by linkage of antigen gene to an HSP70 gene.

Nucleic acid vaccines represent an attractive approach to generating antigen-specific immunity because of their stability and simplicity of delivery. However, there is still a need to increase the potency of DNA vaccines. Using human papillomavirus type 16 E7 as a model antigen, we evaluated the effect of linkage to Mycobacterium tuberculosis heat shock protein 70 (HSP70) on the potency of antigen-specific immunity generated by naked DNA vaccines. We found that vaccines containing E7-HSP70 fusion genes increased the frequency of E7-specific CD8+ T cells by at least 30-fold relative to vaccines containing the wild-type E7 gene. More importantly, this fusion converted a less effective vaccine into one with significant potency against established E7-expressing tumors. Surprisingly, E7-HSP70 fusion vaccines exclusively targeted CD8+ T cells; immunological and antitumor effects were completely CD4-independent. These results indicate that fusion of HSP70 to an antigen gene may greatly enhance the potency of DNA vaccines via CD8-dependent pathways.

Animals↗
PubMed2000

Detection of Chlamydia trachomatis DNA in archival paraffinized specimens from chronic salpingitis cases using the polymerase chain reaction.

OBJECTIVE: To identify Chlamydia trachomatis by the polymerase chain reaction (PCR) in fallopian tube tissues with chronic salpingitis. DESIGN: Retrospective case-control study. SETTING: Academic tertiary institution. PATIENT(S): Women with a pathological diagnosis of chronic salpingitis or normal fallopian tube hospitalized between September 1992 and November 1994. Initial identification of 248 specimens with final analysis of 154. INTERVENTION(S): Paraffin-embedded fallopian tube tissues were analyzed with use of PCR to detect C. trachomatis. MAIN OUTCOME MEASURE(S): Identification of C. trachomatis DNA; demographics of age, ethnicity, parity, history of sexually transmitted disease, and surgical procedure. RESULT(S): C. trachomatis DNA was detected in 9 of 77 chronic salpingitis cases. Seventy-seven controls were negative for C. trachomatis. No statistically significant difference in age or ethnicity between cases and controls was identified. Nulliparity was more frequent in cases (26 of 74) than controls (14 of 76). Sexually transmitted disease history was more prevalent in cases (24 of 74) than controls (6 of 76). Chlamydia infection was not associated with a particular surgical indication. CONCLUSION(S): Chronic salpingitis is highly associated with the presence of C. trachomatis infection as detected by PCR.

Adolescent↗
PubMed2000

Antigen-specific immunotherapy for human papillomavirus 16 E7-expressing tumors grown in the liver.

BACKGROUND/AIMS: We have previously reported a recombinant vaccinia-based vaccine (vac-Sig/E7/LAMP-1) that demonstrated a significant anti-tumor effect in a subcutaneous tumor challenge model. Since the liver is one of the most common sites for tumor metastasis and organ microenvironments may modulate tumor cell responses to therapies, the aim of the present study was to evaluate the potency of vac-Sig/E7/LAMP-1 in treating E7-expressing tumors grown in the liver. METHODS: For in vivo tumor prevention experiments, mice were vaccinated intraperitoneally with vac-Sig/E7/LAMP-1 followed by intrahepatic tumor challenge. For in vivo tumor regression experiments, mice were first challenged with tumor cells and then vaccinated with vac-Sig/E7/LAMP-1 intraperitoneally. In addition, enzyme-linked immunospot assays were used to determine the frequency of E7-specific T cell precursors. RESULTS: For in vivo tumor protection experiments, tumor growth was observed in all of the mice vaccinated with wild-type vaccinia and 60% of the mice vaccinated with wild-type E7 vaccinia. All of the mice vaccinated with vac-Sig/E7/LAMP-1 remained tumor-free 30 days after tumor challenge. For the tumor regression assays, all of the mice vaccinated with vac-Sig/E7/LAMP-1 remained tumor-free 30 days after vaccination. In contrast, all of those mice receiving culture medium, wild-type vaccinia, or wild-type E7 vaccinia developed tumors in the liver. In addition, mice vaccinated with vac-Sig/E7/LAMP-1 had the highest E7-specific CD8+ T cell precursors. CONCLUSIONS: Our data suggest that vac-Sig/E7/LAMP-1 is an effective vaccine for controlling E7-expressing tumors grown in the liver and our model suggests that antigen-specific immunotherapy may represent a powerful tool for treating liver tumors with characterized tumor-specific antigens. In addition, our data indicate that the number of E7-specific CD8+ T cell precursors directly correlated with the anti-tumor effect generated by Sig/E7/LAMP-1 vaccinia.

Animals↗
PubMed2000

Evaluation of using dog as an animal model to study the fraction of oral dose absorbed of 43 drugs in humans.

PURPOSE: To conduct a retrospective evaluation of using dog as an animal model to study the fraction of oral dose absorbed (F) of 43 drugs in humans and to briefly discuss potential factors that might have contributed to the observed differences in absorption. METHODS: Mean human and dog absorption data obtained under fasted state of 43 drugs with markedly different physicochemical and pharmacological properties and with mean F values ranging from 0.015 to 1.0 were obtained from the literature. Correlation of F values between humans and dogs was studied. Based on the same references, additional F data for humans and rats were also obtained for 18 drugs. RESULTS: Among the 43 drugs studied, 22 drugs were virtually completely absorbed in both dogs and humans. However, the overall correlation was relatively poor (r2 = 0.5123) as compared to the earlier rat vs. human study on 64 drugs (r2 = 0.975). Several drugs showed much better absorption in dogs than in humans. Marked differences in the nonliner absorption profiles between the two species were found for some drugs. Also, some drugs had much longer Tmax values and prolonged absorption in humans than in dogs that might be theoretically predicted. Data on 18 drugs further support great similarity in F between humans and rats reported earlier from our laboratory. CONCLUSIONS: Although dog has been commonly employed as an animal model for studying oral absorption in drug discovery and development, the present study suggests that one may need to exercise caution in the interpretation of data obtained. Exact reasons for the observed interspecies differences in oral absorption remain to be explored.

Acarbose↗
PubMed2000

Apparent lack of effect of P-glycoprotein on the gastrointestinal absorption of a substrate, tacrolimus, in normal mice.

PURPOSE: To study the contribution of P-glycoprotein (P-gp) to the oral absorption of a substrate, tacrolimus, by comparing the extent and rate of bioavailability in normal and mdr1a knockout mice. Methods. Intravenous and oral (2 mg/kg) blood concentration data of tacrolimus in normal and knockout mice were obtained from a study by K. Yokogawa et al. in Pharm. Res. 16:1213-1218 (1999). Mean bioavailability (F), mean hepatic first-pass extraction ratio (Fh), mean bioavailability rates, mean oral clearance, and mean total hepatic intrinsic clearance were calculated using standard pharmacokinetic methods. RESULTS: The mean F of tacrolimus (an apparently highly permeable compound) was increased from 0.22 in normal mice to 0.72 in knockout mice. These values were consistent with mean predicted Eh (based on intravenous data) of 0.77 and 0.27 in normal and knockout mice, respectively. Great similarity in the relative bioavailability profile (such as short Tmax) between normal and knockout mice was also found. Mean oral clearance and mean total or unbound hepatic intrinsic clearance of tacrolimus in knockout mice were found to be about 10 times lower compared to those in normal mice. CONCLUSIONS: The above results suggest an apparent lack of effect of P-gp on the gastrointestinal absorption of tacrolimus in normal mice under the study condition. It is postulated that the effect of P-gp on the rate and extent of oral absorption should be more pronounced for those more slowly or incompletely absorbed drugs (i.e., drugs with relatively low permeabilities) as illustrated by talinolol in humans. The clearance data also suggest a very dominant role of P-glycoprotein in controlling the rate of hepatic metabolism of tacrolimus in normal mice, and P-glycoprotein may serve as an effective efflux pump for direct transport of metabolites formed in hepatocytes into the blood circulation.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2000

Intramuscular administration of E7-transfected dendritic cells generates the most potent E7-specific anti-tumor immunity.

Dendritic cells (DCs) are highly efficient antigen-presenting cells capable of priming both cytotoxic and helper T cells in vivo. Recent studies have demonstrated the potential use of DCs that are modified to carry tumor-specific antigens in cancer vaccines. However, the optimal administration route of DC-based vaccines to generate the greatest anti-tumor effect remains to be determined. This study is aimed at comparing the levels of immune responses and anti-tumor effect generated through different administration routes of DC-based vaccination. We chose the E7 gene product of human papillomavirus (HPV) as the model antigen and generated a stable DC line (designated as DC-E7) that constitutively expresses the E7 gene. Among the three different routes of DC-E7 vaccine administration in a murine model, we found that intramuscular administration generated the greatest anti-tumor immunity compared with subcutaneous and intravenous routes of administration. Furthermore, intramuscular administration of DC-E7 elicited the highest levels of E7-specific antibody and greatest numbers of E7-specific CD4+ T helper and CD8+ T cell precursors. Our results indicate that the potency of DC-based vaccines depends on the specific route of administration and that intramuscular administration of E7-transfected DCs generates the most potent E7-specific anti-tumor immunity.

Animals↗
PubMed2000

Granulocyte-macrophage colony-stimulating factor priming plus papillomavirus E6 DNA vaccination: effects on papilloma formation and regression in the cottontail rabbit papillomavirus--rabbit model.

A cottontail rabbit papillomavirus (CRPV) E6 DNA vaccine that induces significant protection against CRPV challenge was used in a superior vaccination regimen in which the cutaneous sites of vaccination were primed with an expression vector encoding granulocyte-macrophage colony-stimulating factor (GM-CSF), a cytokine that induces differentiation and local recruitment of professional antigen-presenting cells. This treatment induced a massive influx of major histocompatibility complex class II-positive cells. In a vaccination-challenge experiment, rabbit groups were treated by E6 DNA vaccination, GM-CSF DNA inoculation, or a combination of both treatments. After two immunizations, rabbits were challenged with CRPV at low, moderate, and high stringencies and monitored for papilloma formation. As expected, all clinical outcomes were monotonically related to the stringency of the viral challenge. The results demonstrate that GM-CSF priming greatly augmented the effects of CRPV E6 vaccination. First, challenge sites in control rabbits (at the moderate challenge stringency) had a 0% probability of remaining disease free, versus a 50% probability in E6-vaccinated rabbits, and whereas GM-CSF alone had no effect, the interaction between GM-CSF priming and E6 vaccination increased disease-free survival to 67%. Second, the incubation period before papilloma onset was lengthened by E6 DNA vaccination alone or to some extent by GM-CSF DNA inoculation alone, and the combination of treatments induced additive effects. Third, the rate of papilloma growth was reduced by E6 vaccination and, to a lesser extent, by GM-CSF treatment. In addition, the interaction between the E6 and GM-CSF treatments was synergistic and yielded more than a 99% reduction in papilloma volume. Finally, regression occurred among the papillomas that formed in rabbits treated with the E6 vaccine and/or with GM-CSF, with the highest regression frequency occurring in rabbits that received the combination treatment.

Animals↗
PubMed2000

Immunotherapy of a human papillomavirus type 16 E7-expressing tumor by administration of fusion protein comprised of Mycobacterium bovis BCG Hsp65 and HPV16 E7.

Human papillomavirus type 16 (HPV16) infection has been linked to the development of cervical and anal dysplasia and cancer. One hallmark of persistent infection is the synthesis of the viral E7 protein in cervical epithelial cells. The expression of E7 in dysplastic and transformed cells and its recognition by the immune system as a foreign antigen make it an ideal target for immunotherapy. Utilizing the E7-expressing murine tumor cell line, TC-1, as a model of cervical carcinoma, an immunotherapy based on the administration of an adjuvant-free fusion protein comprised of Mycobacterium bovis BCG Hsp65 linked to HPV16 E7 (HspE7) has been developed. Initial in vitro analyses indicate that immunization with HspE7 results in the induction of a type 1 immune response based on the pattern of secreted cytokines and the presence of cytolytic activity following antigenic recall. It has been previously shown that prophylactic immunization with HspE7 protected mice against challenge with TC-1 cells and that these tumor-free animals are also protected against rechallenge with TC-1 cells. The present report shows that a single therapeutic immunization with HspE7 induces regression of palpable tumors, confers protection against tumor rechallenge, and is associated with long-term survival (>253 days). In vivo studies using mice with targeted mutations in CD8 or MHC class II or depleted of CD8 or CD4 lymphocyte subsets demonstrate that tumor regression following therapeutic HspE7 immunization is CD8 dependent and CD4 independent. These studies extend previous observations on the induction of CTL by Hsp fusion proteins and are consistent with the clinical application of HspE7 as an immunotherapy for human cervical and anal dysplasia and cancer.

Animals↗
PubMed2000

Similarity in the linear and non-linear oral absorption of drugs between human and rat.

OBJECTIVE: The main aim of this study was to provide a simple, pharmacokinetic rationale for great similarity in the extent (Fab) of gastrointestinal absorption of about 100 different, diverse compounds between human and the rat in linear dosing range, and to test the general applicability of a novel empirical method to correlate the non-linear Fab between the human and the rat by normalizing doses by body surface area (BSA) or body weight 0.67. METHOD: The mean small intestinal transit time (t) of 36 rats was estimated from the reported study, and this was used to compare with that in humans. The reported great similarity in apparent first-order absorption rate constants (k) of seven structurally diverse compounds between the two species were obtained. Extensive computer search was made and non-linear Fab data for the two species were obtained for chlorothiazide, acyclovir, miglitol and pafenolol. RESULTS: The mean t for rats was estimated to be 3.32 h which is almost identical to that reported in humans. The great similarity in Fab between human and rat in linear absorption range can be rationalized by similar t and k between the two species. The markedly different Fab vs dose/kg of body weight profiles between human and rat for the four drugs showing dose-dependent Fab were found to collapse when doses were normalized by BW0.67. CONCLUSION: For Fab not limited by the solubility problem, the great similarity in Fab between human and rat in linear absorption range can be rationalized by the similar t and k. For non-linear Fab drugs, great similarity in Fab can also be obtained between human and rat when doses are normalized by BSA or BW0.67. Regardless of absorption properties (active, passive or facilitated), similar Fab between the two species may be generally obtained when doses used in humans are about 5 to 7 times lower than that in rats. The above findings may be valuable in drug development.

1-Deoxynojirimycin↗
PubMed2000

Safety and efficacy of the platelet glycoprotein IIb/IIIa inhibitor abciximab in Chinese patients undergoing high-risk angioplasty.

BACKGROUND: Platelets are believed to play a role in the ischemic complications of coronary angioplasty, such as abrupt closure of coronary vessels during or soon after the procedure. Accordingly, we evaluated the effect of a chimeric monoclonal antibody abciximab, directed against the platelet glycoprotein IIb/IIIa receptor, in patients undergoing angioplasty who were at high risk for ischemic complications. This receptor is the final common pathway for platelet aggregation. METHODS: In a prospective, double-blind trial, we randomly assigned 42 patients to receive a bolus and an infusion of placebo or a bolus and an infusion of abciximab. Low-dose, weight-adjusted heparin (initial dose of 70 U/kg of body weight) was used in both groups. Patients underwent coronary angioplasty for high-risk clinical situations involving unstable angina or high-risk coronary morphologic characteristics. The primary study end-point consisted of any of the following: death, nonfatal myocardial infarction, unplanned surgical revascularization, unplanned repeat percutaneous procedure, unplanned implantation of a coronary stent, or insertion of an intra-aortic balloon pump for refractory ischemia within 30 days of randomization. RESULTS: Compared with placebo, the abciximab resulted in a trend toward reduction in periprocedural myocardial infarction from 15% to 0%, although the differences were not statistically significant (p = 0.099). There were no significant differences between the two groups in the risk of major and minor bleeding and the need for blood transfusion. CONCLUSIONS: Inhibition of platelet glycoprotein IIb/IIIa receptor with abciximab, together with low-dose, weight-adjusted heparin, had a favorable trend toward the reduction of periprocedural myocardial infarction in patients undergoing high-risk angioplasty, without increasing the risk of hemorrhage.

Abciximab↗
PubMed2000

Midcycle administration of single-dose GnRHa for luteal phase failure in women with ovarian hyperstimulation. A report of five cases.

BACKGROUND: Exogenous administration of gonadotropin-releasing hormone agonist (GnRHa) induces an endogenous midcycle gonadotropin surge. However, its use to induce ovulation and maintain luteal function in non-in vitro fertilization patients who receive ovarian stimulation is unknown. CASES: Five infertile women who underwent controlled ovarian hyperstimulation with human menotropin developed multiple ovarian follicles. In an attempt to circumvent the potential ovarian hyperstimulation syndrome, 1 mg of leuprolide acetate was administered subcutaneously to three patients in an attempt to induce the endogenous luteinizing hormone surge. All three patients began menstruation six to seven days after GnRHa administration with serum progesterone levels between 0.2 and 0.5 ng/mL. Similar ovarian stimulation cycles with ovulation induced by human chorionic gonadotropin in these individuals revealed a normal luteal phase length and midluteal progesterone levels. When double doses of leuprolide acetate were used on two patients, normal luteal length and midluteal serum progesterone levels occurred. CONCLUSION: A single bolus of GnRHa during the late follicular phase may be inadequate to initiate normal luteal function in cycles with ovarian hyperstimulation.

Adult↗
PubMed2000

Toxic megacolon secondary to infective colitis in children.

BACKGROUND AND PURPOSE: Toxic megacolon is a fulminating and potentially lethal complication of severe colitis. Toxic megacolon secondary to infective colitis in children is rare. We analyzed the clinical course, pathology, treatment, and outcome of toxic megacolon secondary to infective colitis in children. METHODS: The medical records of all 20 children treated for infective colitis complicated with toxic megacolon during a 12-month (October 1997-October 1998) period were retrospectively reviewed. RESULTS: There were 10 boys and 10 girls, with a mean (+/- standard deviation, SD) age of 26.2 +/- 12.9 months (range, 6-57 mo). With an initial presentation of nonspecific gastroenteritis syndrome lasting several days, the disease progressed rapidly. In the acute stage, most patients developed toxic signs such as mental change, ranging from irritability to stupor (20, 100%), fever (19, 95%), tachycardia (20, 100%), abdominal distension (20, 100%), and abnormal stool pattern (19, 95%). Initial investigations revealed anemia (11, 55%), leukocytosis (11, 55%), and elevated levels of C-reactive protein ranging from 25.0 mg/L to 483.0 mg/L with a mean +/- SD of 185.7 +/- 129.1 mg/L (normal range, < 8 mg/L) (20, 100%). Salmonella enteritidis (12 patients, 60%) and Clostridium difficile (1, 5%) were isolated from stool samples in some cases. Plain abdominal x-rays revealed severe colonic dilatation. Prolonged hospitalization (mean, 33.6 d) and intensive therapy including a combination of broad-spectrum antibiotics, physical decompression, and total parenteral nutrition were necessary. Three patients (15%) underwent surgical management; the pathologic findings in these patients demonstrated severe transmural inflammation. We believe that bacterial and/or endotoxin translocation played an important role in gut failure. Three patients (15%) in the study died. CONCLUSION: Toxic megacolon in infective colitis is a fulminating illness that has a high mortality rate. The disease course can be divided into three stages: the acute toxic stage, the gut failure stage, and the convalescence or deterioration stage. Early diagnosis and aggressive management are important.

Bacterial Infections↗
PubMed2000

Isolation of Aeromonas hydrophila in children with diarrhea.

Aeromonas species are gram-negative bacilli that lead to a wide spectrum of infectious diseases in human. In the present study, these bacilli were reviewed to assess their significance as enteric pathogens in this area. During the years of 1994 to 1998, the clinical microbiology laboratory received 2150 stool specimens of children with diarrhea. Medical charts of patients who had positive culture for Aeromonas hydrophila were reviewed. A. hydrophila were isolated from 50 (2.3%) of 2150 children with diarrhea. Most patients were outpatients with ages ranging from 5 months to 16 years old (mean age 3.5 years). The male to female ratio was 0.85:1. All patients suffered from watery or loose diarrhea, some with blood-tinged stool. Whether or not they received medication, all patients had uneventful recoveries. The results of antibiotic susceptibility testing revealed that all strains were not susceptible to ampicillin. In summary, A. hydrophila may be considered as a causative agent of gastrointestinal illness in children.

Adolescent↗
PubMed2000

Pulmonary lymphangioleiomyomatosis in a 29-year-old woman with bilateral spontaneous pneumothorax: case report.

Pulmonary lymphangioleiomyomatosis is a rare, progressive and fatal interstitial lung disease that affects women of child-bearing age. It is characterized by the nonneoplastic proliferation of atypical smooth muscle cells around lymphatics, venules, and bronchioles. Patients with pulmonary lymphangioleiomyomatosis most commonly present with exertional dyspnea and a cough. Pneumothorax is almost always found on the initial chest radiograph. We report a case of a 29-year-old woman who presented with abrupt right chest pain and progressive dyspnea. Physical examination in the emergency department was significantly diminished breath sounds over the right lung, and a chest X-ray revealed a right-sided pneumothorax. She required a chest tube for complete lung re-expansion. On the sixth day of admission, left-sided pneumothorax occurred and another chest tube was inserted. She underwent high-resolution computed tomography of the thorax with the findings of numerous cysts evenly distributed throughout the parenchyma of both lungs. Bilateral thoracotomy with lung biopsies and pleurodesis were performed and the surgical findings confirmed the presence of multiple, small, pink-colored cystic lesions on the surfaces of both lungs. Pathological examination showed the characteristic findings of pulmonary lymphangioleiomyomatosis.

Adult↗
PubMed1999

Targeting human papillomavirus type 16 E7 to the endosomal/lysosomal compartment enhances the antitumor immunity of DNA vaccines against murine human papillomavirus type 16 E7-expressing tumors.

DNA vaccination is an attractive approach for tumor immunotherapy because of its stability and simplicity of delivery. Advances demonstrate that helper T cell responses play a critical role in initiating immune responses. The aim of the current study is to test whether targeting HPV-16 E7 to the endosomal/lysosomal compartment can enhance the potency of DNA vaccines. We linked the lysosome-associated membrane protein 1 (LAMP-1) to HPV-E7 to construct a chimeric DNA, Sig/E7/LAMP-1 DNA. For in vivo tumor prevention experiments, mice were vaccinated with E7 DNA or Sig/E7/LAMP-1 DNA via gene gun, followed by tumor challenge. For in vivo tumor regression experiments, mice were first challenged with tumor cells and then vaccinated with E7-DNA or Sig/E7/LAMP-1 DNA. Intracellular cytokine staining with flow cytometry analysis, cytotoxic T lymphocyte (CTL) assays, enzyme-linked immunoabsorbent assay (ELISA), and enzyme-linked immunospot (ELISPOT) assays were used for in vitro E7-specific immunological studies. In both tumor prevention and tumor regression assays, Sig/E7/LAMP-1 DNA generated greater antitumor immunity than did wild-type E7 DNA. In addition, mice vaccinated with Sig/E7/LAMP-1 DNA had greater numbers of E7-specific CD4+ helper T cells, higher E7-specific CTL activity, and greater numbers of CD8+ T cell precursors than did mice vaccinated with Sig/E7 or wild-type E7 DNA. Sig/E7 generated a stronger E7-specific antibody response than did Sig/E7/LAMP-1 or wild-type E7 DNA. Our results indicate that linkage of the antigen gene to an endosomal/lysosomal targeting signal may greatly enhance the potency of DNA vaccines.

Animals↗
PubMed1999

Differential coronary microvascular function in patients with left ventricular dysfunction of unknown cause--implication for possible mechanism of myocardial ischemia in early stage of cardiomyopathy.

To evaluate whether or not coronary microvascular dysfunction is associated with exercise-induced myocardial ischemia in left ventricular dysfunction of unknown cause, both the treadmill exercise test (TET) and coronary hemodynamics were studied in 20 patients with impaired left ventricular ejection fraction (<50% by radionuclide ventriculogram), normal cardiac size, normal coronary angiogram and no evidence of clinical heart failure. Ten subjects with atypical chest pain were studied as the control. Coronary hemodynamics were studied both at baseline and after dipyridamole infusion (0.56mg/kg, i.v. for 4'). There was no difference in age, gender, blood pressure, baseline great cardiac venous flow (GCVF) and coronary vascular resistance between ten patients with a positive TET and the other ten with a negative TET. At baseline, coronary sinus oxygen concentration was increased and myocardial oxygen consumption reduced in patients with a positive TET compared with those with negative a TET. After dipyridamole infusion, maximum GCVF (102+/-47 vs. 144+/-31 ml/min, P=0.027) and coronary flow reserve (2.31+/-0.49 vs. 3.00+/-0.61, P=0.012) were significantly reduced and minimum coronary vascular resistance was higher (1.00+/-0.42 vs. 0.63+/-0.12 mmHg/ml/min, P=0.016) in patients with a positive TET than in those with a negative TET. At follow-up, 40% of patients with a positive TET and 10% of those with a negative TET developed clinical heart failure with a dilated left ventricle during a period of 45 months. Thus, coronary microvascular function is heterogeneous in patients with left ventricular dysfunction of unknown cause. In some of them, coronary microvascular dysfunction could be related to the presence of exercise-induced myocardial ischemia, suggesting that similar pathophysiology underlies the early stage of dilated cardiomyopathy and syndrome X.

Adult↗
PubMed1999

Competitive inactivation of a double-strand DNA break site involves parallel suppression of meiosis-induced changes in chromatin configuration.

In Saccharomyces cerevisiae, DNA double-strand breaks (DSBs) initiate meiotic recombination at open sites in chromatin, which display a meiosis-specific increase in micrococcal nuclease (MNase) sensitivity. The arg4 promoter contains such a DSB site. When arg4 sequences are placed in a pBR322-derived insert at HIS4 (his4 :: arg4 ), the presence of strong DSB sites in pBR322 sequences leads to an almost complete loss of breaks from the insert-borne arg4 promoter region. Most of the MNase-sensitive sites occurred at similar positions in insert-borne and in normal ARG4 sequences, indicating that hotspot inactivation is not a consequence of changes in nucleosome positioning. However, a meiosis-specific increase in MNase hypersensitivity was no longer detected at the inactive insert-borne arg4 DSB site. Elimination of pBR322 sequences restored DSBs to the insert-borne arg4 promoter region and also restored the meiotic induction of MNase hypersensitivity. Thus, the meiotic induction of MNase hypersensitivity at the DSB sites is suppressed and activated in parallel to DSBs themselves, without changes in the underlying DNA sequence or nucleosome positioning. We suggest that meiosis-specific changes in chromatin at a DSB site are a signal reflecting a pivotal step in DSB formation.

Argininosuccinate Lyase↗