Pharmacokinetics and effects of demographic factors on blood 25(OH)D3 levels after a single orally administered high dose of vitamin D3.

AIM: To examine the biological consequences and demographic factors that might affect the pharmacokinetics of vitamin D3 after a single high dose intervention in a young Chinese population with vitamin D insufficiency status. METHODS: A total of 28 young subjects (25 to 35 years old) with vitamin D insufficiency status [serum 25(OH)D <30 ng/mL] was recruited in Shanghai, China. The subjects were orally administered a single high dose of vitamin D3 (300 000 IU). Baseline characteristics and blood samples were collected at d 0, 1, 2, 3, 7, 28, 56, 84 and 112 after the intervention. The blood biomarker levels were determined with standardized methods. RESULTS: The intervention markedly increased the blood 25(OH)D3 levels within the first five days (mean Tmax=5.1±2.1 d) and sustained an optimal circulating level of 25(OH)D3 (≥30 ng/mL) for 56 d. After the intervention, body weight and baseline 25(OH)D3 levels were significantly correlated with circulating 25(OH)D3 levels. No adverse events and no consistently significant changes in serum calcium, creatinine, glucose, parathyroid hormone, vitamin D binding protein, or the urinary calcium/reatinine ratio were observed. However, there was a significant increase in phosphorus after the vitamin D3 intervention. Total cholesterol and triglyceride levels were decreased at the end of the trial. CONCLUSION: The pharmacokinetics of vitamin D after intervention were influenced by baseline 25(OH)D3 levels and the body weight of the subjects. The results suggest that a single high oral vitamin D3 intervention is safe and efficient for improving the vitamin D status of young Chinese people with vitamin D insufficiency.

Pungent ginger components modulates human cytochrome P450 enzymes in vitro.

AIM: Ginger rhizome is used worldwide as a spicy flavor agent. This study was designed to explore the potential effects of pungent ginger components, 6-, 8-, and 10-gingerol, on human cytochrome P450 (CYP450) enzymes that are responsible for the metabolism of many prescription drugs. METHODS: The activities of human CYP2C9, CYP2C19, CYP2D6, and CYP3A4 were analyzed using Vivid P450 assay kits. The mRNA expression of CYP3A4 in human hepatocellular carcinoma cell line HepG2 was measured using quantitative real-time PCR assay. RESULTS: All three gingerols potently inhibited CYP2C9 activity, exerted moderate inhibition on CYP2C19 and CYP3A4, and weak inhibion on CYP2D6. 8-Gingerol was the most potent in inhibition of P450 enzymes with IC50 values of 6.8, 12.5, 8.7, and 42.7 µmol/L for CYP2C9, CYP2C19, CYP3A4, and CYP2D6, respectively. By comparing the effects of gingerols on CYP3A4 with three different fluorescent substrate probes, it was demonstrated that the inhibition of gingerols on CYP3A4 had no substrate-dependence. In HepG2 cells, 8-gingerol and 10-gingerol inhibited, but 6-gingerol induced mRNA expression of CYP3A4. CONCLUSION: 6-, 8-, and 10-gingerol suppress human cytochrome P450 activity, while 8- and 10-gingerol inhibit CYP3A4 expression. The results may have an implication for the use of ginger or ginger products when combined with therapeutic drugs that are metabolized by cytochrome P450 enzymes.

Dihydroartemisinin promotes angiogenesis during the early embryonic development of zebrafish.

AIM: To investigate the embryotoxicity of dihydroartemisinin (DHA), the main active metabolite of artemisinin, in zebrafish, and explore the corresponding mechanisms. METHODS: The embryos of wild type and TG (flk1:GFP) transgenic zebrafish were exposed to DHA. Developmental phenotypes of the embryos were observed. Development of blood vessels was directly observed in living embryos of TG (flk1:GFP) transgenic zebrafish under fluorescence microscope. The expression of angiogenesis marker genes vegfa, flk1, and flt1 in the embryos was detected using real-time PCR and RNA in situ hybridization assays. RESULTS: Exposure to DHA (1-10 mg/L) dose-dependently caused abnormal zebrafish embryonic phenotypes in the early developmental stage. Furthermore, exposure to DHA (10 mg/L) resulted in more pronounced embryonic angiogenesis in TG (flk1:GFP) zebrafish line. Exposure to DHA (10 mg/L) significantly increased the mRNA expression of vegfa, flk1, and flt1 in the embryos. Knockdown of the flk1 protein partially blocked the effects of DHA on embryogenesis. CONCLUSION: DHA causes abnormal embryonic phenotypes and promotes angiogenesis in zebrafish early embryonic development, demonstrating the potential embryotoxicity of DHA.

Preclinical assessment of anti-cancer drugs by using RP215 monoclonal antibody.

RP215 monoclonal antibody was originally generated against OC-3-VGH ovarian cancer cells. It was shown to recognize specifically a carbohydrate-associated epitope(s) of cancer cell-expressed immunoglobulin heavy chains designated as CA215. Previous studies suggest that CA215 is expressed by all human cancer cell lines and tissues in both membrane bound and secreted forms. It may be an ideal target for therapeutic treatments of human cancers with humanized RP215-related antibodies. Based on the results of large scale immunohistochemical studies (50-100 cases each), the following types of cancers revealed high percentage(s) of positive staining with RP215: esophagus (76%), stomach (50%), colon (44%), ovary (64%), breast (32%), lung (31%), cervix (84%) and endometrium (78%). Nude mouse experiments were performed to determine if RP215 has any inhibitory effect on the growth of cancer cells in vivo. Following injections of a single dose (10 mg/kg) of I(131)-labeled RP215 (specific activity, 12.5 muCi/mg), the tumor size (OC-3-VGH ovarian cancer cells) was reduced to 30% of the untreated control within two weeks. By injecting the same dose, the unlabeled RP215 also reduced the tumor size to 50% of the control during the same period. The antibody treatments were found to have little effect on the body weight as well as apparent toxicity of these animals. To proceed with clinical trial studies of RP215-based anti-cancer drugs, chimeric form of this monoclonal antibody was generated and characterized. Through our effort, the "proof of concept" of anti-cancer drugs development was clearly established for the next stages of clinical trial studies.

Lack of definable nucleation sites in the rate-limiting transition state of barnase under native conditions.

It has been shown that the burst-phase (submillisecond) intermediate of barnase, if it exists, can be only marginally more stable than the fully unfolded state at pH 6.3 and 25 degrees C. In the study reported here, no stable burst-phase intermediate could be detected, even in the presence of stabilizing salt (0.4 M Na(2)SO(4)). These results suggest that a burst-phase intermediate with even marginal stability does not exist. The absence of such an intermediate in turn suggests the need for re-examination of the rate-limiting transition state (RLTS) under native conditions, which was previously characterized by using a three-state model with a stable intermediate and protein engineering. Surprisingly, mutations throughout the structure of barnase do not significantly affect the folding rate, suggesting a lack of specific favorable interactions among the side-chains in the RLTS. This RLTS is clearly different from that previously characterized under denaturing conditions, indicating that changes take place in the RLTS under native and denaturing conditions. The occurrence of such changes is further supported by the observation that the unfolding rate constants of barnase and its mutants were divergent or convergent as a function of denaturant concentrations. Consistent with changes in the RLTS, a re-analysis of data from native-state hydrogen exchange studies has shown that the logarithm of the unfolding rate constant inflects down under low concentrations of denaturant. Here, we discuss in detail the question of whether changes in the RLTS involve a kinetically silent intermediate that occurs after the initial RLTS.