Biomedical subjects

Y Tian

Publications and source records attributed to Y Tian.

258 records · Page 15Linked to original sources

PubMedDate not supplied

Micronucleus formation in 3-day mouse embryos associated with maternal exposure to chlorpyrifos during the early preimplantation period.

Chlorpyrifos, an organophosphate pesticide, was evaluated for its ability to induce cytogenetic damage in preimplantation embryos after maternal exposure. Pregnant female mice were intraperitoneally (i.p.) administered a single dose of chlorpyrifos (40 or 80 mg/kg) at 10:00 h on Day 0 of pregnancy. On Day 3 of gestation, blastocysts were collected and evaluated for gross morphology, micronucleus (MN) frequency, and cell number. A significant increase in MN frequency indicating cytogenetic damage was observed in the treatment groups in comparison to control. The MN frequency revealed a clear dose-dependent increase. There was also a significant decrease in the embryo cell number in the 80 mg/kg treated group. A simultaneous decrease in the cell number and increase in MN frequency may reflect an embryonic developmental disadvantage resulting from maternal treatment with chlorpyrifos.

Animals↗

PubMedDate not supplied

Comparison of theory and experiment in pulsatile flow in cat lung.

A mathematical model of pulsatile flow in cat lung based on existing morphometric and elastic data is presented and validated by experimental results. In the model, the pulmonary arteries and veins were treated as elastic tubes, whereas the pulmonary capillaries were treated as two-dimensional sheets. The macro- and microcirculatory vasculature was transformed into an analog electrical circuit. Input impedances of the pulmonary blood vessels of every order were calculated under normal physiological conditions. Pressure-flow relation of the whole lung was predicted theoretically. Experiments on isolated perfused cat lungs were carried out. The relation between pulsatile blood pressure and blood flow was measured. Comparison of the theoretically predicted input impedance spectra with those of the experimental results showed that the modulus spectra were well predicted, but significant differences existed in the phase angle spectra between the theoretical predictions and the experimental results. This latter discrepancy cannot be explained at present and needs to be further investigated.

Animals↗

PubMedDate not supplied

Signaling events activated by angiotensin II receptors: what goes before and after the calcium signals.

Angiotensin II (Ang II) receptors of the AT1 subtype are coupled to heterotrimeric G nucleotide-binding proteins, G(q/11), to activate phospholipase C-beta isoforms with production of inositol 1,4,5-trisphosphate (InsP3) and diacylglycerol. The resultant release of intracellular Ca2+ and increased Ca2+ influx are major determinants of several acute cellular responses initiated by Ang II, including secretion of aldosterone from the adrenal cortex and smooth muscle contraction. However, cellular events related to more prolonged effects of Ang II, such as hypertrophic and hyperplastic responses, are triggered by intracellular signaling cascades that are less dependent on Ca2+ signals. The Ang II-induced activation of Raf-1 kinase, p42 MAP-kinase and c-fos expression in response to Ang II in adrenal glomerulosa cells does not require Ca2+ influx. Moreover, the dose-response relationships for Raf-1 activation, MAP-kinase activation and mitogenesis show significantly higher sensitivity to Ang II than the InsP3, Ca2+-release and aldosterone secretory responses. The sensitivities of both Raf-1 kinase and MAP-kinase stimulation by Ang II to the inhibitors of phosphoinositide kinases, wortmannin and LY 294002, suggest that inositol phospholipids may play a role in these activation events unrelated to their role in Ca2+ signaling. To investigate the changes of various inositides after stimulation at the single cell level, fluorescent probes were developed in which pleckstrin homology domains with distinct binding specificities to inositol phospholipids were fused to the green fluorescent protein and expressed in NIH 3T3 cells. The use of these probes revealed heterogeneity of the inositol lipid pools and their complex relationship to Ca2+ signals. The use of these tools will help to further clarify the complex role of these lipids in initiating Ca2+-dependent and -independent signaling responses.

3T3 Cells↗

PubMedDate not supplied

Chronic disease associated with long-term concentrations of nitrogen dioxide.

A prospective epidemiologic cohort study of 6,000 residentially stable and non-smoking Seventh-day Adventists (SDA) in California was conducted to evaluate long-term cumulative levels of ambient nitrogen dioxide (NO2) in association with several chronic diseases. These diseases included respiratory symptoms, cancer, myocardial infarction (MI), and all natural causes mortality. Cumulative ambient concentrations of NO2 were estimated for each study subject using monthly interpolations from fixed site monitoring stations and applying these estimates to the monthly residence and work place zip code histories of study participants. In addition, a personal NO2 exposure study on a randomly selected sample of 650 people in southern California was conducted to predict total personal NO2 exposure using household and lifestyle characteristics and ambient NO2 concentrations. It was found that good predictability could be obtained (correlation coefficient between predicted and observed values = 0.79) from a model predicting personal NO2. The resulting regression equations from the personal NO2 exposure study were applied to the epidemiologic study cohort to adjust ambient concentrations of NO2.

Adult↗

PubMedDate not supplied

Particulate contamination from siliconized rubber stoppers--a statistical evaluation.

Siliconized stoppers, when used with parenteral drug products, have been shown to be a source of particulate contamination. In this study, five different variables: pH of the solution, buffer concentration, Teflon coating on the stopper, autoclaving cycle (F0), and lot-to-lot variation of the siliconization process were evaluated using an eight-run Plackett-Burman design with respect to their impact on the level of particulate contamination from siliconized stoppers. Results show that pH of the solution can significantly affect the particulate level of samples using siliconized stoppers (p < 0.05). An alkaline solution (pH = 8) was shown to produce a higher particulate load than an acid solution (pH = 4). The main effect of the remaining four variables was determined to be statistically insignificant (p > 0.15).

Analysis of Variance↗

PubMedDate not supplied

California residential air exchange rates and residence volumes.

UNLABELLED: Air exchange rate data from two residential indoor air quality studies are presented. In the first investigation, over 500 residences in Southern California were sampled for three one-week periods from 1984 to 1985. Those data provided seasonal information for a broad range of residential characteristics in a large metropolitan area. In the second study, a probability sample of nearly 300 residences were sampled for a two-day period during the winter of 1991-1992 throughout the state of California. Air exchange rate is summarized by season, geographic area, and appliance type. Residence volumes are presented by cooking and heating appliance. The data approximately followed lognormal distributions. IMPLICATIONS: Indoor air quality and human exposure models often require estimates of air exchange rate and residence volumes. Application of those models to California residences can be improved by using the data distributions provided in this manuscript. Data distributions presented for heating and cooking appliances are useful for modeling the impact of indoor sources specific for those appliance types. Measured air exchange rate is also useful for modeling energy use for heating and cooling in residences.

Air Pollution, Indoor↗