Quantitative fluoride imaging of teeth using CaF emission by laser induced breakdown spectroscopy.

In this work, we propose the use of molecular emission of calcium fluoride (CaF) by laser induced breakdown spectroscopy (LIBS) to obtain quantitative fluoride distribution images of teeth. LIBS has proved to be an efficient technique to detect low amounts of fluoride in solids, and human teeth have the advantage being a matrix rich in calcium. We used new calibration material from sintered hydroxyapatite pellets doped with fluoride to determine the optimized LIBS conditions of argon flow at 1 L min and using the green emission bands of CaF in 530 nm, and obtained a calibration curve between 0 and 400 μg g, and LOD of 18 μg g.

Human embryos in a dish - modeling early embryonic development with pluripotent stem cells.

Stem cell-based embryo models present new opportunities to study early embryonic development. In a recent study, Kagawa et al. identified an approach to create human pluripotent stem cell-based blastoids that resemble the human blastocysts.

International Regulatory and Scientific Effort for Improved Developmental Neurotoxicity Testing.

The Organisation for Economic Co-Operation and Development (OECD) coordinates international efforts to enhance developmental neurotoxicity (DNT) testing. In most regulatory sectors, including the ones dealing with pesticides and industrial chemicals registration, historical use of the in vivo DNT test guideline has been limited. Current challenges include a lack of DNT data and mechanistic information for thousands of chemicals, and difficulty in interpreting results.

From the Cover: Teratogenic Effects of in Utero Exposure to Di-(2-Ethylhexyl)-Phthalate (DEHP) in B6:129S4 Mice.

Intrauterine exposure to phthalates is known to cause disorders of male reproductive function including androgen insufficiency, decreased fertility, and germ cell defects in rodents. In this study, we set out to investigate the effects of intrauterine exposure to di-(2-ethylhexyl)-phthalate (DEHP) on fetal development of the B6:129S4 mouse strain. Time-mated pregnant C57BL/6 dams were exposed to 0, 5, 250, or 500 mg/kg DEHP with corn oil as the vehicle via oral gavage from embryonic days (E)7 to 16.

Using parental phenotypes in case-parent studies.

In studies of case-parent triads, information is often collected about history of the condition in the parents, but typically parental phenotypes are ignored. Including that information in analyses may increase power to detect genetic association for autosomal variants. Our proposed approach uses parental phenotypes to assess association independently of the usual case-parent-based association test, enabling cross-generational internal replication for findings based on offspring and their parents.

isocir: An R Package for Constrained Inference using Isotonic Regression for Circular Data, with an Application to Cell Biology.

In many applications one may be interested in drawing inferences regarding the order of a collection of points on a unit circle. Due to the underlying geometry of the circle standard constrained inference procedures developed for Euclidean space data are not applicable. Recently, statistical inference for parameters under such order constraints on a unit circle was discussed in Rueda (2009); Fernández (2012).

The impact of classification of interest on predictive toxicogenomics.

The era of toxicogenomics has introduced a new way of monitoring the effect of environmental stressors and toxicants on biological systems via quantification of changes in gene expression. Because the liver is one of the major organs for synthesis and secretion of substances which metabolize endogenous and exogenous materials, there has been a great deal of interest in elucidating predictive and mechanistic genomic markers of hepatotoxicity. This mini-review will bring context to a limited number of toxicogenomics studies which used genomics to evaluate the transcriptional changes in blood and liver in response to acetaminophen (APAP) or other liver toxicants, but differed according to the classification of interest (COI), i.

Biokinetics and subchronic toxic effects of oral arsenite, arsenate, monomethylarsonic acid, and dimethylarsinic acid in v-Ha-ras transgenic (Tg.AC) mice.

Previous research demonstrated that 12-O-tetradecanoylphorbol-13-acetate (TPA) treatment increased the number of skin papillomas in v-Ha-ras transgenic (Tg.AC) mice that had received sodium arsenite [(As(III)] in drinking water, indicating that this model is useful for studying the toxic effects of arsenic in vivo. Because the liver is a known target of arsenic, we examined the pathophysiologic and molecular effects of inorganic and organic arsenical exposure on Tg.

Serial levels of serum organochlorines during pregnancy and postpartum.

In utero exposure to dichlorodiphenyldichloroethene and polychlorinated biphenyls, within the range found in the general U.S. population, may produce detectable effects in offspring.

Overexpression of the cardiac Na+/Ca2+ exchanger increases susceptibility to ischemia/reperfusion injury in male, but not female, transgenic mice.

Influx of Ca2+ into myocytes via Na+/Ca2+ exchange may be stimulated by the high levels of intracellular Na+ and the changes in membrane potential known to occur during ischemia/reperfusion. This increased influx could, in turn, lead to Ca2+ overload and injury. Overexpression of the cardiac Na+/Ca2+ exchanger therefore may increase susceptibility to ischemia/reperfusion injury.

A measure of tumorigenic potency incorporating dose-response shape.

Many researchers have considered the problem of ranking chemical agents based on their carcinogenic potency. Sawyer et al. (1984, Biometrics 40, 27-40) proposed a carcinogenic potency estimate that incorporates both intercurrent mortality and background tumor rates.

General antimutators are improbable.

Antimutator mutations reduce spontaneous mutation rates, at least at some sites and along some pathways. Antimutators have been found in several microbial systems since their initial discovery in bacteriophage T4, where they occur mainly among mutations of gene 43 (which encodes the viral DNA polymerase). The phage T4 antimutators are highly specific, often strongly reducing mutations rates but only along specific pathways, usually A.

Species differences in carcinogenesis.

There are differences in response of different species to many carcinogens. Different organs respond to particular carcinogens, there are differences in potency (including resistance of some species), and there are varying effects of other parameters. Although animal studies identify carcinogens, it is impossible to predict accurately the potency or the target organ in humans of any carcinogen.

Measurement of intracellular ionized magnesium.

Recent advances in methods for measuring Mgi have advanced our understanding of Mgi homeostasis. Several methods exist for measuring Mgi; all have strengths and weaknesses and one needs to match the experimental needs with the limitations of the method. For example, if one needs rapid (ms) time resolution, or only relative directional changes in a cell that is not easily impaled with an electrode, the fluorescent indicators may best suit ones needs.

Metabolism of tris(2-chloroethyl) phosphate in rats and mice.

Tris(2-chloroethyl) phosphate (TRCP), a flame retardant, produces a dose-, sex-, and species-dependent lesion in the hippocampal region of the brain following subchronic oral administration. This lesion is more common and more severe in female F344 rats than in male F344 rats, and is not observed in B6C3F1 mice. The present investigation of the metabolism of TRCP was designed to detect sex and species variations that might account for differences in toxicity.

Brain distribution and fate of tris(2-chloroethyl) phosphate in Fischer 344 rats.

Tris(2-chloroethyl) phosphate (TRCP) is a flame retardant that has a wide variety of industrial applications. In subchronic studies, oral administration of TRCP to rats and mice has been reported to produce dose-, sex-, and species-dependent lesions in the hippocampal brain region. The present investigation has examined the metabolism, elimination, and regional brain distribution of [14C]TRCP in male and female rats.

A third essential DNA polymerase in S. cerevisiae.

DNA polymerases I and III are essential for viability of S. cerevisiae. We have cloned and analyzed POL2, the gene encoding the catalytic subunit of the third nuclear DNA polymerase, DNA polymerase II.

Differential effects of colchicine lesions of dentate granule cells on wet dog shakes and seizures elicited by direct hippocampal stimulation.

Direct electrical stimulation of either the dorsal or ventral hippocampal formation elicits wet dog shakes and overt seizures. Destruction of dentate granule cells in the dorsal hippocampal formation does not significantly reduce the number of wet dog shakes elicited by ventral hippocampal stimulation. However, destruction of dentate granule cells in the ventral hippocampus virtually eliminates wet dog shaking elicited by dorsal hippocampal stimulation.

Human hepatocyte and kidney cell metabolism of 2-acetylaminofluorene and comparison to the respective rat cells.

The metabolism and mutagenic activation of 2-acetylaminofluorene by human and rat hepatocytes and kidney cells were measured. High performance liquid chromatography was used to separate the 2-acetylaminofluorene metabolites, and a cell-mediated Salmonella typhimurium mutagenesis assay was used to detect mutagenic intermediates. Rat and human differences were observed with cells from both organs and levels of metabolism and mutagenesis were higher in human cells.

Prenatal exposure of male mice to diethylstilbestrol alter the expression of the lactotransferrin gene in seminal vesicles.

We have previously isolated an estrogen-inducible secretory protein, lactotransferrin (LTF), and a cDNA to its messenger RNA from the uterus of mice. In this report we determined that the level of LTF mRNA is minimal in the seminal vesicles of normal mice. In contrast, expression of LTF mRNA in the seminal vesicles of developmentally estrogenized males was both constitutive and estrogen inducible.