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Biomedical subjects

W H Liu

Publications and source records attributed to W H Liu.

At least 37 records · Page 2Linked to original sources
PubMed1999

DNA binding studies of a solvatochromic fluorescence probe 3-methoxybenzanthrone.

A fluorescence probe of 3-methoxybenzanthrone (MBA) exhibits significant solvatochromic characteristics correlated with the polarity of solvents. The interaction of the solvatochromic fluorescence probe with calf thymus DNA (ct-DNA) has been investigated. In the presence of ct-DNA the fluorescence of MBA is strongly quenched with a blue-shift of emission peak and a hypochromism in absorption spectra. The absorption spectra, fluorescence quenching and fluorescence polarization experiments show that the MBA molecule as an intercalator is inserted into the base-stacking domain of the ct-DNA double helix, and the interaction of the nucleobases with the MBA molecule causes quenching of fluorescence and hypochromism in the absorption spectra. The intrinsic binding constant and the binding site number were determined to be 1.70 x 10(5) mol l-1 in base pairs and six, respectively. The I0/I versus [ct-DNA] plot shows linear relationship in the range covering 4.3 x 10(-7)-1.02 x 10(-4) mol l-1 in base pairs which can be used for ct-DNA determination. The limit of detection was found to be 4.3 x 10(-7) mol l-1 in base pairs (0.5 microgram ml-1).

Absorption↗
PubMed1998

Mortalization of human promyelocytic leukemia HL-60 cells to be more susceptible to sodium butyrate-induced apoptosis and inhibition of telomerase activity by down-regulation of nucleophosmin/B23.

Vanadate (10 microM), a potent inhibitor of tyrosine phosphatase, added simultaneously potentiated BuONa-induced (1 mM) apoptosis. The steady-state level of nucleophosmin/B23 mRNA and the total cellular nucleophosmin/B23 protein decreased during the BuONa/vanadate-induced apoptosis. Stabilization and promotor transcriptional activity assays indicate that the decrease in nucleophosmin/B23 mRNA in BuONa/vanadate-treated HL-60 cells was transcriptionally regulated. A decline in telomerase activity was observed in HL-60 cells treated with BuONa/vanadate for 24-96 h. There was virtually no decline of nucleophosmin/B23 mRNA nor the telomerase activities during the growth arrest by serum-starvation. The decrease in nucleophosmin/B23 mRNA expression and telomerase activity in HL-60 cells subsequent to BuONa/vanadate treatment can thus be attributed to cellular apoptosis rather than the growth arrest induced by BuONa/vanadate. Nucleophosmin/B23 antisense oligomer treatment significantly potentiated BuONa-induced apoptosis and inhibition of telomerase activity. Results of this study suggest that nucleophosmin/B23 is one of the key elements in the down-regulation of nucleolar function for cellular apoptosis and mortalization.

Apoptosis↗
PubMed1998

TFF1 gene expression in human medullary thyroid carcinoma.

Medullary thyroid carcinoma (MTC) is an uncommon tumour of calcitonin-secreting C-cells of the thyroid gland. This cancer represents an important potential model for the study of mechanisms of human epithelial cell transformation. Although recent studies have identified the gene involved in familial forms of MTC, little is known about the molecular pathogenesis of the sporadic variants of this tumour. The biological and prognostic significance of TFF1 expression, particularly in diverse human malignancies, suggests that the TFF1 protein could have a role in human neoplasia. Furthermore, in prostate cancer it has been demonstrated that TFF1 expression is closely associated with premalignant changes and neuroendocrine differentiation. In the present study, the expression of TFF1 was analysed in 18 human MTCs, comprising sporadic and familial tumours, C-cell hyperplasia, and one case of lymph gland metastasis. TFF1 expression was also examined in the cultures of a human MTC-derived tumour cell line (TT cell line). The results showed that ten sporadic tumours, three hereditary tumours (including C-cell hyperplasia), and one lymph gland metastasis displayed TFF1 immunoreactivity. Indirect fluorescence immunocytochemistry and Western blotting revealed that the TFF1 protein was strongly expressed in the TT cells. Northern analysis revealed that tumours and TT cells expressed the TFF1 transcript. Although the function of TFF1 protein in the carcinogenesis of MTC remains to be elucidated, its expression in the majority of cases of both sporadic and hereditary tumours, metastatic tumours, and in C-cell hyperplasia suggests that it may contribute to the pathogenesis of MTC.

Adolescent↗
PubMed1998

Glucose-induced oxidative stress in vascular contractile cells: comparison of aortic smooth muscle cells and retinal pericytes.

Free radical-mediated damage to vascular cells may be involved in the pathogenesis of diabetic vasculopathy. The aim of this study was to compare the extent of glucose-induced oxidative stress in both vascular smooth muscle cells (VSMCs) and pericytes and the effect on antioxidant enzyme gene expression and activities. Porcine aortic VSMC and retinal pericytes were cultured in either 5 or 25 mmol/l glucose for 10 days. Intracellular malondialdehyde (MDA) was measured as a marker of peroxidative damage, and mRNA expression of CuZn-SOD, MnSOD, catalase, and glutathione peroxidase (GPX) were measured by Northern analysis. Glutathione (GSH) was also measured. There was a significant increase in MDA in VSMCs in 25 mmol/l glucose (1.34 +/- 0.11 vs. 1.88 +/- 0.24 nmol/mg protein, 5 vs. 25 mmol/l D-glucose, mean +/- SE, n = 15, P < 0.01), but not in pericytes (0.38 +/- 0.05 vs. 0.37 +/- 0.05 nmol/mg protein, n = 11). There was a significant decrease in GSH in both cell types (VSMC, 1.40 +/- 0.13 vs. 0.69 +/- 0.12 nmol/mg protein, n = 15, P < 0.001; pericytes, 1.97 +/- 0.17 vs. 0.94 +/- 0.16 nmol/mg protein, n = 11, P < 0.001). mRNA expression of CuZnSOD and MnSOD was increased only in VSMCs (by 58.5 +/- 8.1 and 41.0 +/- 6.9%, respectively, n = 8, P < 0.01). CuZnSOD protein was increased by approximately 120% (P < 0.00001). None of the antioxidant enzyme activities was altered between 5 and 25 mmol/l glucose in either cell type. Both MnSOD activities and GSH concentrations were higher in pericytes compared with VSMC under basal (5 mmol/l) conditions (P < 0.05 and P < 0.02, respectively). These results demonstrate glucose-induced reduction of GSH in both cells, but only in VSMC is there evidence of oxidant damage in the form of lipid peroxidation, implying significant differences in intracellular responses to glucose between contractile cells in the macro- and microvasculature.

Animals↗
PubMed1998

Bcl-2 and c-Myc, but not bax and p53, are expressed during human medullary thyroid tumorigenesis.

Medullary thyroid carcinoma (MTC) is a tumor of parafollicular cells of the thyroid gland. It has served as a useful experimental model for the study of tumor proliferation and differentiation. Although recent studies have identified the gene involved in familial forms of MTC, little is known about the molecular pathogenesis of the sporadic variants of this tumor. It has become increasingly clear that deregulation of programmed cell death is a critical component in multistep tumorigenesis. The present investigation was undertaken to determine whether similar molecular events occur in human MTC. Eighteen MTCs from 18 patients (including 12 sporadic and six familial cases and one metastatic lymph gland) and a MTC cell line (TT cells) were used in this study for detecting the expression of apoptosis-regulatory genes bcl-2, bax, c-myc, and p53. Immunohistochemical results showed that all MTC tumor samples displayed Bcl-2 and c-Myc immunoreactivity, whereas only 4 and 2 tumors showed a minority of cells positive for Bax and p53, respectively. Western and Northern blotting showed high levels of 26-kd Bcl-2 protein and bcl-2 transcript. The co-expression of Bcl-2 and c-Myc was also detected in the TT cells by indirect fluorescence immunohistochemistry and Western blotting. Moreover, Bcl-2 immunoreactivity was also found in C-cell hyperplasia from familial patients indicating that expression of this oncogene may represent an early event in the pathogenesis of MTC. The present study suggests that deregulation of programmed cell death may be a critical component in multistep tumorigenesis of MTC and that the frequent expression of the Bcl-2 oncoprotein in these tumors may contribute to their pathogenesis. The genetic complementation of simultaneously deregulated bcl-2 and c-myc may be implicated in the multistep tumorigenesis of human MTC.

Adolescent↗
PubMed1997

Expression of a breast-cancer-associated protein (pS2) in human neuro-endocrine tumours.

pS2 protein expression has been demonstrated in a range of malignant tissues in an oestrogen-independent pathway. Recently, it has been demonstrated that pS2, in prostate cancer, is closely associated with neuro-endocrine differentiation. In the present study, we have analyzed, by immunohistochemistry along with microwave antigen retrieval, the expression of pS2 protein in a retrospective series of 236 human primary neuro-endocrine tumours and attempted to correlate this with the clinicopathologic features of patients and the presence of oestrogen receptor (ER). pS2 immunoreactivity was detected in 42% of small-cell lung carcinomas, 36% of lung carcinoids, 33% of phaeochromocytomas, 38% of carotid-body tumours, 31% of pancreatic neuro-endocrine tumours, 60% of stomach carcinoids, 55% of ileal carcinoids, 23% of appendiceal carcinoids and 86% of rectal carcinoids respectively in more than 10% tumour cells. No pituitary tumours displayed pS2 immunoreactivity. pS2 transcript was also detected in lung carcinoid and carotid-body tumours by Northern-blot analysis. There was a statistically higher incidence of pS2 expression in carcinoid tumours of the ileum and rectum than in those of the appendix. No association was observed between pS2 expression and the occurrence of the carcinoid syndrome; nor was any correlation observed between the occurrence of pS2 immunoreactivity and that of ER. Our results suggest that the expression of the pS2 protein in a wide spectrum of neuro-endocrine tumours may be implicated in the pathogenesis and progression of some neuro-endocrine tumours in an oestrogen-independent pathway.

Adrenal Gland Neoplasms↗
PubMed1997

Production of testosterone from cholesterol using a single-step microbial transformation of Mycobacterium sp.

A novel single-step microbial transformation process for the production of testosterone (TS) from cholesterol by Mycobacterium sp was investigated. It was found that the supply of reducing power, NADH, from the metabolism of glucose was necessary for the reduction of androst-4-en-3,17-dione (AD) to TS. The cultivation time for the maximum accumulation of TS and the residual glucose increased in parallel with the amount of glucose supplemented in fermentation cultures. After the glucose in the fermentation culture was completely consumed, most of the TS was oxidized to AD. Adding a larger amount of glucose could prevent oxidation of TS to AD. Under optimal fermentation conditions, the maximum molar conversion rate of TS from cholesterol was 51% in a 5-L surface-aerated fermentor after 120 h cultivation.

Cholesterol↗
PubMed1997

Nitric oxide increased interleukin-4 expression in T lymphocytes.

Nitric oxide (NO) is a regulator of many biological functions including T helper 1 (Th1)/T helper 2 cells balance. It has been demonstrated that NO inhibits the secretion of interleukin-2 (IL-2) and interferon-gamma on Th1 cells. Here we showed that, in addition to the suppression of IL-2 production, NO-generating agents sodium nitroprusside (SNP) and S-nitroso-N-acetylpenicillamine (SNAP) increased the secretion of IL-4 both in Th2 clones and EL4 T cells. The additive effect was dependent on the dose of SNP and SNAP. Augmentation of IL-4 production was detected with 1 microM SNP, and up to threefold increase in IL-4 secretion could be observed with higher concentrations of SNP/SNAP. NO also weakly increased the activation of IL-4 promoter. In contrast, NO markedly inhibited the induction of IL-2 promoter, which could account for most of the reduction in IL-2 production. Analysis of the transcriptional elements on IL-2 and IL-4 promoters revealed a selective inactivation of NF-kappa B and NF-AT. It is suggested that despite the complex feedback network regulating NO production, the enhanced IL-4 expression would lead to the expansion of Th2 cells once NO is generated.

Cell Culture Techniques↗
PubMed1997

Correlation between field dependence-independence and handball shooting by Swedish national male handball players.

Contradictory claims exist as to whether field dependence or field independence is advantageous to team ball-game performance. For further investigation, Swedish national male handball players' Rod-and-Frame Test scores were correlated with their field-goal shooting attempts and shooting efficiency in the '94 European Handball Championship. No significant correlation was found; discussion followed.

Field Dependence-Independence↗
PubMed1996

Detection of numerical chromosome anomalies in interphase cells of ovarian carcinomas using fluorescence in situ hybridization.

Fluorescence in situ hybridization was used in interphase cells of 30 ovarian carcinomas to detect numerical changes in copy number of 13 different centromeres (1, 2, 3, 4, 6, 7, 8, 10, 11, 12, 17, 18, and X). Thirty-seven percent of samples (11/30) were near diploid and demonstrated only minor changes in centromere copy number, involving gain and/or loss of one or a few centromeres. The most common changes included loss of centromeres 4,6, 17, and 18 and gain of centromere 1. The remaining 63% of samples were hyperdiploid and demonstrated a general increase in copy number of most or all centromeres examined. Among these samples, the centromere of chromosome I was most often found to be at higher copy number. Centromeres that were less often at increased copy or deleted within the hyperdiploid samples include centromeres 4, 17, 18, and X. These results suggest that tumor-suppressor genes that are located on chromosomes 4, 6, 17, and 18 may be involved in the development and progression of ovarian cancer.

Adult↗
PubMed1996

ERBB2 and chromosome 17 centromere studies of ovarian cancer by fluorescence in situ hybridization.

More than 26,000 new cases of ovarian cancer are identified each year in the United States, with almost 75% of these malignancies in advanced stages at the time of diagnosis. Early-stage disease has a cure rate of up to 90%, but the long-term survival rate of patients with advanced disease is 5-20%. At this time, there are no biomarkers that are effective indicators of early ovarian cancer. Recently, immunohistochemical and Southern blot studies have suggested that overexpression/amplification of the oncogene ERBB2 (HER2/neu) is associated with aggressive ovarian malignancies; however, some studies have not supported this conclusion. Because tumor cells are known to be highly heterogeneous, we used fluorescence in situ hybridization (FISH) to study individual ovarian cancer cells for HER2/neu amplification and chromosome 17 centromere copy number. Simultaneous multicolor cohybridization of HER2/neu and chromosome 17 centromere alpha-satellite probes were carried out on 43 ovarian cancer samples. Ten of the forty-three samples showed moderate to high amplification of HER2/neu, with varying numbers of chromosome 17 centromeres present. In some cells the amplified HER2/neu was dispersed throughout the nucleus, whereas in other cells the amplified oncogenes were clustered together. Within a sample there was heterogeneity in oncogene and centromere copy number. In this small study, we were unable to identify a specific clinical correlation. However, FISH is a powerful method for the study of oncogene amplification in tumor samples.

Adult↗
PubMed1996

Review of recent Chinese research on field dependence-independence in high-level athletes.

A review of seven studies in China concerning field dependence-independence among 500 athletes in 10 different sports is presented. Athletes participating in closed-skill sports were more field-independent than those in open-skill sports. In closed-skill sports, high-level athletes were more field-independent than those of medium level. In open-skill sports involving direct contact, high-level athletes were more field-dependent than those of medium level. No significant relationship was found between field dependence-independence and athletes' performance in open skill sports in which no direct contact was involved.

Adolescent↗
PubMed1996

[Research on factors affecting neonatal tetanus and its prevention through immunization].

Neonatal Tetanus (NT) has been set by WHO as one of the most important diseases to be under control. Its incidence rate at some counties and cities in Southern Fujian province exceeded set out levels. Both retrospective and cohort studies were carried. It was found that in rural areas only 8.66% (319/3,683) pregnant women gave births at hospital and 94.85% (129/136) NT cases were delivered by untrained midwives. When TAT was tested in mothers and newborns, only 23.81% and 20.65% of them reached protective level. This shows the main reasons for high NT incidence rate were due to poor medical treatment during delivery and low antibody level. Using tetanus toxin (TT) to fully immunize pregnant women, no side effects were observed and TAT antibody levels for mothers and newborns were increasing to reach 100% (99/99) and 93.94% (93/99) relatively. When immunizing women at child-bearing age with TT, 90.40% (113/125) of them still had TAT up to protective level in 3 years. A total number of 8,882 newborns whose mothers had been fully vaccinated with TT were investigated, no NT case occurred. Among 4,835 newborns whose mothers did not receive vaccination, some NT cases were identified. The incidence rate was as high as 5.28%. These results showed that the TT vaccination in women at child-bearing age should be considered as the major strategy for NT prevention.

Adolescent↗
PubMed1994

Changes in lymphocyte reactivity to modulatory factors following low dose ionizing radiation.

Catecholamines (CA) and corticosterone (CS) exerted modulatory effect on the proliferative activity of splenic and thymic lymphocytes in response to mitogenic stimulation in vitro. Epinephrine (E) and norepinephrine (NE) potentiated proliferation in concentrations above 1 and 10 nmol/L, respectively, while CS showed a biphasic effect, stimulating proliferation at concentrations below 0.1 nmol/L and suppressing proliferation at concentrations above 10 nmol/L. Combination of CS with E, NE or both in an ineffective concentration of each (0.1 nmol/L) showed stimulatory effect on the proliferative response of both splenic and thymic lymphocytes to Con A. Whole-body irradiation (WBI) of mice with 75 mGy increased the reactivity of splenic and thymic lymphocytes to Con A. It is reported for the first time in the present paper that the proliferative reactivity of splenic and thymic lymphocytes from low dose irradiated mice could be further increased in the presence of suboptimal concentrations of CS and E as well as suboptimal concentrations of phorbol myristate acetate (PMA) and A23187. These findings may have significance in the mechanism of immunologic stimulation after low dose WBI.

Animals↗
PubMed1993

[Treatment of congestive heart failure complicating chronic Keshen disease with magnesium sulfate and captopril].

150 hospital patients of chronic Keshen disease with congestive heart failure were divided into two groups: the treatment group (TG) and control group (CG). Patients in TG (80 patients) were treated with magnesium sulfate and captopril, while those in CG (70 patients) with digoxin. The results showed a marked difference (P < 0.01) in the total effective ratio between TG (92.5 percent) and CG (65.7 percent). Both groups had an increase in cardiac output and cardiac index, but it was more apparent in TG. With sum vessel resistance (SVR), TG had a remarkable decrease (P < 0.01), patients in while those in CG did not (P > 0.05). The results also showed that the therapeutic effect in TG was satisfactory. The important function of magnesium, the basis of its treatment and the simultaneous administration of magnesium and captopril to reduce the cardiac preload and afterload and to improve the heart function were discussed.

Adolescent↗
PubMed1993

[Alternative combination chemotherapy with mitomycin C, vincristine, methotrexate, 5-fluorouracil, cis-platinum and adriamycin for adenocarcinoma of the lung].

Efficacy of an alternative combination chemotherapy with MMC, VCR, MTX, 5-FU, CDDP and ADM for adenocarcinoma of the lung is reported. Forty-one advanced cases (stage III: 9; IV: 32) were chosen for the chemotherapy. Two combination chemotherapies MMC + VCR + MTX + 5-FU + CDDP: MVMFP; MMC + VCR + MTX + 5-FU + ADM: MVMFA were repeated alternatively for 8 consecutive weeks with 2 interposed rest weeks, and this regimen was completed in 34 cases. All 41 cases were evaluable. Three and 26 cases achieved complete and partial responses, respectively. The response rate was 70.7%, and the median survival time was 13 months. The adverse effects of the chemotherapy observed were tolerable: alopecia (63.4%), gastrointestinal symptoms (14.5%), bone marrow toxicity (12.2%) and liver dysfunction (4.8%). These results indicate that our MVMFP/MVMFA alternative chemotherapy is quite effective for adenocarcinoma of the lung, comparable or superior to conventional chemotherapies.

Adenocarcinoma↗