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Biomedical subjects

R Tang

Publications and source records attributed to R Tang.

At least 73 records · Page 4Linked to original sources
PubMed1999

Alimentary lipemia, postprandial triglyceride-rich lipoproteins, and common carotid intima-media thickness in healthy, middle-aged men.

BACKGROUND: Alimentary lipemia has been associated with coronary heart disease and common carotid artery intima-media thickness (IMT). This study was designed to investigate the relations of subclasses of postprandial triglyceride-rich lipoproteins (TRLs) with IMT. METHODS AND RESULTS: Ninety-six healthy 50-year-old men with an apolipoprotein (apo) E3/E3 genotype underwent an oral fat tolerance test and B-mode carotid ultrasound examination. The apo B-48 and apo B-100 contents of each fraction of TRLs were determined as a measure of chylomicron remnant and VLDL particle concentrations. In the fasting state, LDL cholesterol (P<0.05) and basal proinsulin (P<0. 05) were significantly related to IMT, whereas HDL cholesterol, plasma triglycerides, and insulin were not. In the postprandial state, plasma triglycerides at 1 to 4 hours (P<0.01 at 2 hours), total triglyceride area under the curve (AUC) (P<0.05), incremental triglyceride AUC (P<0.01), and the large VLDL (Sf 60 to 400 apo B-100) concentration at 3 hours (P<0.05) were significantly related to IMT. Multivariate analyses showed that plasma triglycerides at 2 hours, LDL cholesterol, and basal proinsulin were consistently and independently related to IMT when cumulative tobacco consumption, alcohol intake, waist-to-hip circumference ratio, and systolic blood pressure were included as confounders. CONCLUSIONS: These results provide further evidence for postprandial triglyceridemia as an independent risk factor for early atherosclerosis and also suggest that the postprandial triglyceridemia is a better predictor of IMT than particle concentrations of individual TRLs.

Alcohol Drinking↗
PubMed1999

Physical activity, water intake and risk of colorectal cancer in Taiwan: a hospital-based case-control study.

The age-adjusted mortality rates of colorectal cancer have been rising in Taiwan over the past 2 decades, and colorectal cancer is now the third leading cause of cancer mortality in the country. We conducted a hospital-based case-control study to clarify the nature of the association between physical activity, water intake and colorectal-cancer risk in Taiwan. A total of 163 subjects (aged 33-80 years) with histologically confirmed primary colorectal cancer and 163 hospital controls were enrolled during 1992. Dietary intake, physical activity and other lifestyle activities were assessed using a comprehensive food-frequency and lifestyle-activity questionnaire. Adjusted odds ratios (OR) and 95% confidence intervals (CI) were estimated using conditional logistic-regression analysis. A strong inverse dose-response relation between increased water intake and rectal cancer was found among men after adjustment for other risk factors (p for trend = 0.0005). The OR for rectal cancer among men in the highest tertile of water intake was 0.08 (95% CI, 0.02-0.35) compared with that among men in the lowest tertile (OR = 1). Similar but not significant trends were seen among women (p = 0.29). The OR for colon cancer among men with active leisure-time physical activity was 0.19 (95% CI, 0.05-0.77) times that among sedentary men (p for trend = 0.03). However, physical activity was not associated with colon-cancer risk among women (p = 0.48). No differences in the amount of water intake were found related to level of physical activity. These findings add to the evidence that leisure-time activity may reduce colon-cancer risk, not only in high-risk but also in low-risk populations, and support the potential beneficial effect of increased water intake in reducing colorectal-cancer risk.

Adult↗
PubMed1999

Analogs of MTII, lactam derivatives of alpha-melanotropin, modified at the N-terminus, and their selectivity at human melanocortin receptors 3, 4, and 5.

In search for selective agonists at human melanocortin-4 receptor, proline-substituted analogs of MTII, a potent nonselective agonist at melanocortin receptors, were prepared by solid-phase syntheses and evaluated for their ability to bind and activate human MC-3, MC-4, and MC-5 receptors. Replacement of Nle(4) with Pro resulted in [Pro(4)]MTII with affinity to and agonist potency at hMC-4R similar to MTII, but with about 400-fold lower potency at hMC-5R and about 20-fold lower potency at hMC-3R. The substantial increase in selectivity of [Pro(4)]MTII with respect to hMC-5R prompted us to investigate additional analogs of MTII with modified N-termini. The Ac-Nle(4) segment, not encompassed in the lactam ring, was substituted with flexible, hydrophobic, or hydrophilic substituents, and also, with residues resembling proline. The similar agonist potency of these peptides to that of MTII at hMC-4R but significantly lower activity of these compounds at hMC-5R demonstrated that the N-terminal fragment of MTII has virtually no effect on the binding affinity and activation at hMC-4R, but it is essential for full potency at hMC-5R.

Amino Acid Substitution↗
PubMed1999

A simplified regimen of weekly high dose 5-fluorouracil and leucovorin as a 24-hour infusion in patients with advanced colorectal carcinoma.

BACKGROUND: Reports of in vitro experiments in colorectal carcinoma cells suggest that prolonged cellular exposure to 5-fluorouracil (5-FU) combined with relatively low concentrations of leucovorin (LV) provides optimal enhancement of 5-FU efficacy. In this study, a simplified regimen of weekly 24-hour infusion of high dose 5-FU combined with a relatively low dose of LV was used to treat patients with advanced colorectal carcinoma. METHODS: Thirty-six patients with advanced colorectal carcinoma received 5-FU, 2600 mg/m2, admixed with LV, 100 mg/m2, in a portable infusion pump administered intravenously over a 24-hour period. High dose 5-FU/LV was delivered once a week for 5 consecutive weeks followed by a 1-week recovery period. All patients were assessable for toxicity and response. RESULTS: Two complete responses and 15 partial responses were observed (response rate of 47.2%; 95% confidence interval, 30.1-64.4%). The median response duration was 9.6 months. The median survival and time to progression were 11.9 months and 7.1 months, respectively. The toxicity was mild and acceptable. The major dose-limiting factors were hand-foot syndrome and fatigue. CONCLUSIONS: This simplified regimen of weekly 24-hour continuous infusion of high dose 5-FU/LV is an effective regimen in the treatment of patients with advanced colorectal carcinoma. Further study of the pharmacokinetics of combination therapy with 5-FU and LV as used in this regimen and its correlation with response and toxicity is warranted.

Adult↗
PubMed1999

Cerebral blood flow does not mediate the effect of brain temperature on recovery of extracellular potassium ion activity after transient focal ischemia in the rat.

Temperature plays an important role in determining outcome following both global and focal brain ischemia. After focal ischemia, the degree of infarction decreases with mild hypothermia and increases with mild hyperthermia. In this study, brain extracellular potassium ion activity and local cerebral blood flow were measured in cerebral cortex during 60 min of middle cerebral artery occlusion and 60 min of re-perfusion. Brain temperature was maintained at 32-34 degrees C (mild hypothermia), 35.5-36.5 degrees C (normothermia), or 37.5-38.5 degrees C (mild hyperthermia) throughout ischemia and re-perfusion. In normothermic animals and to a greater degree in hyperthermic animals, extracellular potassium ion activity showed delayed secondary elevation above pre-ischemia values within 40-60 min after re-perfusion. No secondary elevation of extracellular potassium ion activity was observed in hypothermic animals. There was no difference in cortical blood flow among groups with varying brain temperature, indicating that delayed deterioration of brain potassium ion homeostasis was not caused by temperature dependent alteration of cerebral blood flow. The data suggest that loss of potassium ion homeostasis during re-perfusion after focal cerebral ischemia is caused by cellular rather than vascular dysfunction and may reflect secondary inhibition of energy metabolism.

Animals↗
PubMed1999

Lymphangiosis as a predictor of outcome in patients with primary diffusely infiltrative adenocarcinoma of the colon and rectum.

OBJECTIVE: To investigate the relationships between outcome and clinicopathological factors, DNA flow cytometrical characteristics, and postoperative adjuvant therapy in patients with primary diffusely infiltrative colorectal adenocarcinoma. DESIGN: Inception cohort study. SETTING: A medical center that offers a mixture of primary, secondary, and tertiary care services. PATIENTS: Among 7035 patients undergoing resection of primary colorectal adenocarcinoma from 1980 to 1996, 37 patients with a pathological diagnosis of primary diffusely infiltrative tumor were selected. All patients had received regular follow-up until February 28, 1998, or until death. MAIN OUTCOME MEASURES: Cancer-specific survival compared by log-rank test and Cox regression model. RESULTS: Univariate analyses revealed tumor stage (stages II-III vs. stage IV, P = .01) and severity of lymphangiosis (absent/mild vs. moderate/severe, P = .04) were significant in predicting outcome. A proliferative index of greater than 20% was insignificant (P = .08) in predicting outcome. In a Cox regression model, TNM stage and lymphangiosis were independently correlated with a worse outcome. When compared with tumors having less severe lymphangiosis, the odds ratio of death due to cancer in cases of tumors with moderate to severe lymphangiosis was 2.4 (95% confidence interval, 1.0-5.6; P = .05). CONCLUSION: Lymphangiosis and TNM stage were independently predictive of outcome in patients with primary diffusely infiltrative colorectal cancer.

Adenocarcinoma↗
PubMed1999

Epithelial cell proliferation activity of the biliary ductal system with congenital biliary malformations.

Congenital biliary malformations such as anomalous arrangement of the pancreaticobiliary ductal system (AAPB), congenital cystic dilatation of the common bile duct (CCDB), and congenital biliary strictures at the hepatic hilum (CBSH) are newly designated disease entities and are frequently found in adult patients with biliary malignancy such as gallbladder carcinoma, common bile duct carcinoma, and intrahepatic bile duct carcinoma. In the present study, the relationship of these malformations and biliary malignancy was investigated. We studied 61 gallbladders of patients with AAPB and 56 gallbladders of patients without AAPB; 16 common bile ducts of patients with CCDB (12 with AAPB and 4 without AAPB) and 11 gallbladders of patients without CCDB; and 17 intrahepatic bile ducts of patients with CBSH and 6 intrahepatic bile ducts of patients without CBSH. Tissue sections from the mucosa of the gallbladder, common bile duct, and intrahepatic bile duct were stained for proliferating cell nuclear antigen (PCNA). The PCNA labeling indexes of patients with these malformations were significantly higher than those of patients without these malformations (P < 0.05). Cell proliferation of the epithelia in the biliary ductal system in patients with these congenital biliary malformations was accelerated. Consequently, these congenital malformations appear to be an important risk factor for the occurrence of biliary malignancy.

Adult↗
PubMed1999

Cyclin D1 overexpression allows identification of an aggressive subset of leukemic lymphoproliferative disorder.

The conjunction of clinical features, cell morphology and immunological characteristics allows an accurate diagnosis in most cases of B cell chronic lymphoproliferative disorders (CLD). However, the diagnosis remains uncertain in a small percentage of cases, often referred as to unclassified B cell proliferation or atypical chronic lymphocytic leukemia (CLL). We have studied retrospectively the 192 cases of leukemic CLD seen in our institution over a 3-year period, for which both clinical and routine biological data at presentation were available. Forty cases (20%) did not fit into any of the well-identified categories according to the FAB criteria and remained unclassified. We assessed cyclin D1 expression in all of these cases and found that 10 of them expressed a high level of cyclin D1 protein. We compared the characteristics of these 10 cases with those of the 30 cyclin D1 negative CLD. Despite non-distinctive cytological and phenotypic features, the 10 cyclin D1 positive patients exhibited a strikingly uniform clinical presentation with elevated leukocytosis, massive spleen enlargement and no superficial lymphadenopathy. Their outcome was very poor with a median survival of 10 months, contrasting with the prolonged survival of the cyclin D1 negative patients. The cytological features of tumor cells from these 10 patients with cyclin D1 positive unclassified leukemic CLD were similar to those of the circulating lymphoid cells from 15 patients with histologically proven mantle cell lymphoma (MCL) and primary or secondary blood involvement. Therefore, cyclin D1 expression allowed identification among the unclassified CLD, a subset of aggressive disorders which represent a leukemic counterpart of MCL (mantle cell leukemia). We suggest that determination of cyclin D1 expression by any technique available should be systematically included when investigating atypical CLL.

Adult↗
PubMed1999

Polymerase chain reaction-based enzyme immunoassay for quantitation of telomerase activity: application to colorectal cancers.

Telomerase is a specialized reverse transcriptase that synthesizes telomeric sequences onto human chromosomal ends. It appears to be present in the majority of primary human cancer tissues, and may have potential as a universal tumor marker. In this report, we describe a sensitive, non-radioactive, polymerase chain reaction (PCR)-based enzyme immunoassay (EIA) for the quantitation of telomerase activity in human cells. This PCR-EIA is convenient and can be easily completed within 3 h. The correlation coefficient between the results of PCR-EIA and the conventional telomeric repeat amplification protocol (TRAP) method, as measured on 4 different cell lines, was over 0.98. Evaluation of this method for clinical application was conducted with tissues obtained from patients with colorectal cancers and the results were compared with those of the conventional TRAP method. Our data indicate that telomerase activities measured by conventional TRAP and PCR-EIA are highly correlated, and we suggest that the PCR-EIA method can substitute for conventional TRAP.

Autoradiography↗
PubMed1999

LDL particle size distribution is associated with carotid intima-media thickness in healthy 50-year-old men.

Results of cross-sectional and prospective studies have suggested that small, dense low-density lipoprotein (LDL) particles predispose to coronary heart disease. We investigated the relationships between plasma concentrations of LDL subfractions and intima-media thickness (IMT) of the common carotid artery (CCA), quantified by B-mode ultrasound, in 94 healthy, 50-year-old men, all of whom were homozygous for the apolipoprotein E3 allele. A novel 3% to 7.5% polyacrylamide gradient gel was developed to provide separation of LDL subfractions with high resolution, as was a procedure to quantify plasma concentrations of these LDL subspecies. The LDL particle size distribution pattern obtained by the gradient gel electrophoresis procedure was in good agreement with the one obtained by a well-established, single-spin density gradient ultracentrifugation technique. LDL-II (particle size, 23.5 to 25.0 nm) was the most abundant subfraction, and its plasma concentration correlated closely with the total LDL cholesterol concentration (r=0. 61, P<0.001) but not with CCA IMT (r=-0.13, NS). In contrast, the plasma concentration of the predominant small, dense LDL particle subfraction (LDL-III; particle size, 22.5 to 23.5 nm) correlated strongly with CCA IMT (r=0.42, P<0.001). In multivariate analysis, the plasma concentration of the LDL-III subfraction contributed significantly to the variation in CCA IMT (R(2)=0.19). When plasma triglycerides and LDL cholesterol were forced into the multivariate model, 10% of the variation in CCA IMT was still accounted for by the LDL-III subfraction. In summary, use of a novel and sensitive gradient gel electrophoresis method for evaluation of LDL heterogeneity provided the basis for demonstrating an independent relation between the plasma concentration of small LDL and IMT of the CCA in healthy, middle-aged men.

Apolipoproteins B↗
PubMed1999

Associations of risk factors with segment-specific intimal-medial thickness of the extracranial carotid artery.

BACKGROUND AND PURPOSE: It is generally assumed that risk factors affect extracranial carotid intimal-medial thickness similarly among all arterial segments. This assumption underlies use of single segments or walls of segments as outcome variables for risk factor studies and clinical trials. However, if the impact of risk factors was unequal for various segments or circumferentially asymmetrical within segments, then inferences drawn from a single segment or wall might not be generalizable; furthermore, since individual segments and walls have unique histological characteristics and are differentially exposed to turbulent flow, risk factor relationships with a particular segment or wall may provide inferences regarding pathogenesis of atherosclerosis. METHODS: We evaluated associations of risk factors with intimal-medial thickness at the near and far walls of the common carotid artery, bifurcation, and internal carotid artery in 280 individuals older than 45 years equally divided between coronary artery disease cases and controls and between men and women. RESULTS: The patterns of differences in mean intimal-medial thickness among segments vary, depending on age, history of hypertension, body mass index in women, and coronary (case-control) status. The asymmetry of disease depended on blood glucose concentrations, prior history of diabetes, smoking, and coronary status. Sex, postmenopausal status, LDL cholesterol, systolic blood pressure, and history of myocardial infarction all had statistically significant relationships with intimal-medial thickness that were fairly homogeneous among arterial sites. CONCLUSIONS: Focus on an individual segments or walls of the extracranial carotid arteries may lead to overestimation or underestimation of associations of risk factors with extracranial carotid intimal-medial thickness.

Aged↗
PubMed1999

Collaborative telemedicine between optometry and ophthalmology: an initiative from the University of Houston.

The University of Houston College of Optometry (UHCO) has developed a strong Telemedicine Optometry/Ophthalmology program. Patient care, clinical teaching and research benefit from utilizing Telemedicine technology. This initiative between Optometry and Ophthalmology is at the forefront of eyecare! Presented here: clinical teaching opportunities via tele-education including retinal, uveitic, neuro-ophthalmic disorders and glaucoma. Seminars introduce students to this technology and enhance their clinical experience through exposure to eye pathologies often related to systemic diseases. UHCO's affiliated clinics include multidisciplinary centers staffed by optometrists: the Frost Eye Clinic (HIV multidisciplinary care), Good Neighbor Health Clinic and Rusk School Health Promotion Project (indigent multidisciplinary care). These centers can converse on line with eyecare professionals. Large sites interested in low vision/visual rehabilitation include: The Institute for Rehabilitation and Research (TIRR), the Social Security Hospital (Lima, Peru), the Matagorda General Hospital and the Quentin Mease Hospital. These sites, do offer quality care but require visual rehabilitation programs provided by UHCO. These sites also provide exposure to pathology for the students. A residency program trains optometrists in Telemedicine. The research program focuses on optics and imaging necessary to diagnose glaucoma, diabetic retinopathy, and neuro-ophthalmic disorders through Telemedicine. UHCO supports the advancement of standards in tele-eyecare.

Eye Diseases↗
PubMed1999

[Transvaginal gamete intrafallopian transfer: an analysis of 42 cases].

OBJECTIVE: To develop the technique of transvaginal gamete intrafallopian transfer (TV-GIFT) and to evaluate its effectiveness. METHODS: From May, 1996 to October, 1997, 42 infertile patients with at least one tube patent, proven by hysterosalpingography were included. In 43 cycles, ovarian stimulation was performed by using follicle-stimulating hormone (FSH), human menopausal gonadotropin (hMG)/hCG or hMG/hCG program. Oocytes retrieval was performed by transvaginal ultrasound guided needle aspiration. Semen samples were prepared by modified swim-up method. The Jansen-Andersen tubal catheter was introduced into a fallopian tube transvaginally, and the gametes were injected into the tube. RESULTS: Transvaginal cannulation was successfully performed in 67.4% of cases. The mean number of oocytes transferred was 4.0 +/- 0.9 (2-6) per cycle. 13 cases obtained clinical pregnancy (30.2% per cycle), 9 given birth with 5 twin pregnancies (altogether 13 babies), 4 spontaneous abortions. CONCLUSIONS: TV-GIFT offers an acceptable pregnancy rate for patient with at least one patent tube. The procedure is simple and easy to perform and therefore, is worth to recommend for the treatment of infertility.

Adult↗
PubMed1999

[A preliminary study on hepatitis E virus antibody IgG and IgM for the diagnosis of acute hepatitis E].

OBJECTIVE: To evaluate the significance of hepatitis E virus antibody (anti-HEV) IgG and IgM for the diagnosis of acute hepatitis E. METHODS: Acute phase sera from a total of 143 patients with sporadic hepatitis E in 7 cities of China were determined for anti-HEV IgM and IgG by using an enzyme-linked immunosorbent assay (EIA). 359 serial sera of 56 patients with hepatitis E and 68 serial sera of 4 rhesus macaques experimentally infected with hepatitis E virus (HEV) were also detected for anti-HEV IgG and IgM. RESULTS: In the 143 patients the positive rate of anti-HEV IgG was 100.0%, which was significantly higher than that of anti-HEV IgM (73.4%, 105/143). 97.2% of anti-HEV IgG positive patients had a titer over 1:40. The positive rate of anti-HEV IgM increased with the titer of anti-HEV IgG in sera. It was 0% (0/4), 44.4% (8/18) and 80.2% (97/121), respectively in patients with the anti-HEV IgG titer of 1:20, 1:40 and >or=1:80 (P < 0.001). All the anti-HEV IgM positive patients were also anti-HEV IgG positive. No patients were found to be anti-HEV IgM positive alone. Anti-HEV IgG was detected as early as 2 days after onset of the disease, with a cumulative positive seroconversion rate of 100% by 1 month. The negative seroconversion rate of anti-HEV IgG increased with course of the disease and 43.3% of the patients lost their anti-HEV IgG by 6 months after illness. Though anti-HEV IgM also seroconverted at the same time as anti-HEV IgG, its cumulative positive seroconversion rate was only 71.4% and declined rapidly. Up to 37.5% of anti-HEV IgM positive patients became negative by 1 month after onset. Similar antibody responses were observed in 4 rhesus macaques experimentally infected with HEV. CONCLUSION: It is suggested that as a result of the poor sensitivity of currently available anti-HEV IgM EIA kits, anti-HEV IgG will be a more reliable marker for the diagnosis of acute hepatitis E as compared with anti-HEV IgM.

Acute Disease↗
PubMed1998

Close correlation between telomerase expression and adenomatous polyp progression in multistep colorectal carcinogenesis.

To investigate the role of telomerase in the multistep colorectal carcinogenesis, we examined telomerase activity in 31 adenomatous polyps and 22 paired cancer-normal mucosa specimens from non-hereditary nonpolyposis colorectal cancer patients. Telomerase activity was detected in 18% of normal mucosa, 16% of small (<1.0 cm) polyps, 20% of intermediate polyps, 71% of large (>2.0 cm) polyps, and 96% of adenocarcinoma samples (P for trend, <0.0001). High-level enzyme activities were seen in none of the normal mucosa, 5% of small polyps, 20% of intermediate polyps, 43% of large polyps, and 73% of adenocarcinoma samples (P for trend, <0.0001). These data indicate telomerase reactivation occurs with adenomatous polyp progression in multistep colorectal carcinogenesis.

Adenomatous Polyposis Coli↗
PubMed1998

Identification of a dihydropyridine as a potent alpha1a adrenoceptor-selective antagonist that inhibits phenylephrine-induced contraction of the human prostate.

A number of novel dihydropyridine derivatives based upon 1, 4-dihydro-3-(methoxycarbonyl)-2, 6-dimethyl-4-(4-nitrophenyl)-5-((3-(4, 4-diphenylpiperidin-1-yl)propyl)aminocarbonyl)pyridine (4) have been synthesized and tested at cloned human alpha adrenoceptors as well as the rat L-type calcium channel. Within this compound series, 5-(aminocarbonyl)-1,4-dihydro-2, 6-dimethyl-4-(4-nitrophenyl)-3-((3-(4, 4-diphenylpiperidin-1-yl)propyl)aminocarbonyl)pyridine (19) displayed good binding affinity and selectivity for the alpha1a adrenoceptor (pKi = 8.73) and potently inhibited (pA2 = 9.23) phenylephrine-induced contraction of the human prostate.

Adrenergic alpha-Agonists↗
PubMed1998

Prognostic significance of the cell cycle inhibitor p27Kip1 in chronic B-cell lymphocytic leukemia.

B-cell chronic lymphocytic leukemia (B-CLL) is characterized by the accumulation of resting lymphocytes. The identification of p27(kip1), a cyclin-dependent kinase inhibitor that contributes to cell cycle arrest and represents a link between extracellular signals and cell cycle, prompted us to study p27 protein in the lymphocytes from 88 patients with B-CLL and 32 patients with other chronic B-lymphoproliferative disorders. The expression of p27 protein was higher in B-CLL samples with variations among them. In B-CLL, p27 levels were independent of absolute number of circulating lymphocytes, but strongly correlated with both lymphocyte and total tumor mass (TTM) doubling time. High p27 expression was associated with a poorer overall prognosis. In vitro, there was an increased spontaneous survival of B-CLL cells expressing high p27 levels. Interleukin-4 (IL-4) upregulated p27 levels in B-CLL cells, while fludarabine decreased p27 levels. Thus, our results indicate that p27 may be a valuable kinetic marker in B-CLL by providing instantaneous estimation of the disease doubling time. In addition, these results suggest that there is a link between p27 expression and the ability of CLL cells to undergo apoptosis.

Apoptosis↗