Biomedical subjects

D Luo

Publications and source records attributed to D Luo.

149 records · Page 9Linked to original sources

PubMedDate not supplied

Induction of G1 arrest and differentiation in MDA-MB-231 breast cancer cell by boehmeriasin A, a novel compound from plant.

Boehmeriasin A is a new phenanthroquinolizidine alkaloid recently isolated from the Boehmeria siamensis Craib (Urticaceae). In vitro biological activity assay demonstrated that this novel compound has wide-range, strong antitumor activity. This study is aimed to determine the effects of boehmeriasin A on breast cancer cell (MDA-MB-231 cell line). Proliferation assay and fluorescence activated cell sorter (FACS) showed that cell growth inhibition and G1 phase arrest of cell cycle were caused by boehmeriasin A. The concentrations resulting in total and 50% growth inhibition are 0.007 and 0.0035 microg/mL, respectively. Exposed in 0.007 microg/mL boehmeriasin A for 12 h, the G1 phase cell percent increased from 44.8% pre-drug treatment to 66.3%. Consistent with G1 arrest and cell growth inhibition, cyclin E2 and cyclin D1 messenger RNA expression in the cell was down-regulated with drug treatment. Then, few apoptotic cells were detected, and most other cells underwent differentiation, which is characterized by specific changes in cell morphology, lots of lipid droplet accumulation, and increasing expression of adipocyte differentiation-related protein. The result first demonstrates that boehmeriasin A potently inhibits the proliferation of breast cancer cell MDA-MB-231 via the G1 phase cell cycle arrest and differentiation induction, and as such, may be considered as candidate chemotherapeutic and/or chemopreventive agent for breast cancer.

Apoptosis↗

PubMedDate not supplied

Chemosensitivity of human hepatocellular carcinoma cell line QGY-7703 is related to bcl-2 protein levels.

Bcl-2 protein is one of the major apoptosis regulators. The study examines the effect of Bcl-2 protein on the chemosensitivity of a human hepatocellular carcinoma cell line, QGY-7703. Western blot analysis showed that Bcl-2 and Bax proteins were expressed in QGY-7703 cells. Characteristic features of Taxol- and doxorubicin-induced apoptosis were evidenced by the Annexin-V binding assay, TUNEL and DAPI staining. At constant Bax protein levels, stable sense and antisense gene-transfected QGY-7703 cells showed that constitutive expression of Bcl-2 could render the cells more resistant to Taxol and doxorubicin. Contrarily, decreased Bcl-2 levels caused the cells to be more sensitive to the drugs. As Bcl-2 levels are directly proportional to the resistance of QGY-7703 cells to Taxol and doxorubicin, manipulation of Bcl-2 could be performed to enhance the sensitivity of liver cancer to chemotherapeutic agents.

Annexin A5↗

PubMedDate not supplied

Structure and function of sinusoidal lining cells in the liver.

The hepatic sinusoid harbors 4 different cells: endothelial cells (100, 101), Kupffer cells (96, 102, 103), fat-storing cells (34, 51, 93), and pit cells (14, 107, 108). Each cell type has its own specific morphology and functions, and no transitional stages exist between the cells. These cells have the potential to proliferate locally, either in normal or in special conditions, that is, experiments or disease. Sinusoidal cells from a functional unit together with the parenchymal cells. Isolation protocols exist for all sinusoidal cells. Endothelial cells filter the fluids, exchanged between the sinusoid and the space of Disse through fenestrae (100), which measure 175 nm in diameter and are grouped in sieve plates. Fenestrae occupy 6-8% of the surface (106). No intact basal lamina is present under these cells (100). Various factors change the number and diameter of fenestrae [pressure, alcohol, serotonin, and nicotin; for a review, see Fraser et al (32)]. These changes mainly affect the passage of lipoproteins, which contain cholesterol and vitamin A among other components. Fat-storing cells are pericytes, located in the space of Disse, with long, contractile processes, which probably influence liver (sinusoidal) blood flow. Fat-storing cells possess characteristic fat droplets, which contain a large part of the body's depot of vitamin A (91, 93). These cells play a major role in the synthesis of extracellular matrix (ECM) (34, 39-41). Strongly reduced levels of vitamin A occur in alcoholic livers developing fibrosis (56). Vitamin A deficiency transforms fat-storing cells into myofibroblast-like cells with enhanced ECM production (38). Kupffer cells accumulate in periportal areas. They specifically endocytose endotoxin (70), which activates these macrophages. Lipopolysaccharide, together with interferon gamma, belongs to the most potent activators of Kupffer cells (28). As a result of activation, these cells secrete oxygen radicals, tumor necrosis factor, interleukin 1, interleukin 6, and a series of eicosanoids (28) and become cytotoxic against tumor cells [e.g., colon carcinoma cells (19, 22, 48)]. Toxic secretory products can cause necrosis of the liver parenchyma, which constitutes a crucial factor in liver transplantation (55). Pit cells possess characteristic azurophylic granules and display a high level of spontaneous cytolytic activity against various tumor cells, identifying themselves as natural killer cells (10). The number and cytotoxicity of pit cells can be considerably enhanced with biological response modifiers, such as Zymosan or interleukin 2 (8). Pit cell proliferation occurs within the liver, but recent evidence indicates that blood large granular lymphocytes develop into pit cells in 2 steps involving high- and low-density pit cells (88). Kupffer cells control the motility, adherence, viability, and cytotoxicity of pit cells (89), whereas cytotoxicity against tumor cells is synergistically enhanced (80, 81).

Animals↗

PubMedDate not supplied

Testing a model for posthospital transition of family caregivers for elderly persons.

The purpose of this study was to test a model of factors influencing family caregivers' responses and health outcomes during the 2-month period following an elder's discharge from the hospital for acute episodes of chronic illness. The elder's average age was 72.3 years. The average age of caregivers, 63% of whom were spouses of the elder, was 61 years. A longitudinal design was used for this study. Data were collected from 346 elder/caregiver dyads the day before discharge and at 2 weeks and 2 months postdischarge. Structural equation analysis was used to evaluate the conceptual model. The findings suggest that the model fits the data with an overall Goodness of Fit Index of .80.

Adaptation, Psychological↗

PubMedDate not supplied

A systematic review and meta-analysis of the incidence of cancer in randomized, controlled trials of verapamil.

We conducted a systematic review of all published randomized, controlled trials to assess the risk of cancer or death in patients receiving verapamil for hypertension, angina pectoris, or cardiac arrhythmias. Meta-analysis comparing the risk of new cancers, cancer deaths, and all deaths was performed. Thirty-nine trials comprising 11,201 patients were eligible. Study durations ranged from 8 days-6 years (mean 29.5 wks). Nine trials (6507 patients) were 24 weeks in duration or longer. For cancer and cancer death, OR was 1.20 (95% CI = 0.60-2.42) for verapamil versus active controls and 0.73 (95% CI = 0.39-1.39) for verapamil versus placebo. For all deaths, OR was 1.13 (95% CI = 0.70-1.82) for verapamil versus active controls and 0.85 (95% CI = 0.71-1.00) for verapamil versus placebo. Sensitivity analysis for the 9 trials 24 weeks' duration or longer gave similar results. There is no statistically significant increased risk of cancer or deaths with verapamil compared with active controls or placebo.

Calcium Channel Blockers↗