Visual spatial memory is enhanced in female rats (but inhibited in males) by dietary soy phytoestrogens

Background  

In learning and memory tasks, requiring visual spatial memory (VSM), males exhibit superior performance to females (a difference attributed to the hormonal influence of estrogen). This study examined the influence of phytoestrogens (estrogen-like plant compounds) on VSM, utilizing radial arm-maze methods to examine varying aspects of memory. Additionally, brain phytoestrogen, calbindin (CALB), and cyclooxygenase-2 (COX-2) levels were determined.     

The application of homotopy analysis method to solve nonlinear differential equation governing Jeffery–Hamel flow

In this paper Jeffery–Hamel flow has been studied and its nonlinear ordinary differential equation has been solved through homotopy analysis method (HAM). The obtained solution in comparison with the numerical ones represents a remarkable accuracy. The results also indicate that HAM can provide us with a convenient way to control and adjust the convergence region.     

Neuromodulation by soy diets or equol: Anti-depressive &; anti-obesity-like influences,age- &; hormone-dependent effects

Background  

Soy-derived isoflavones potentially protect against obesity and depression. In five different studies we examined the influence of soy-containing diets or equol injections on depression, serotonin levels, body weight gain (BW) and white adipose tissue (WAT) deposition in female Long-Evans rats at various stages of life [rats were intact, ovariectomized or experienced natural ovarian failure (NOF)].     

Simultaneous quantitation of testosterone and estradiol in human cell line (H295R) by liquid chromatography/positive atmospheric pressure photoionization tandem mass spectrometry

The possible interaction of environmental contaminants with the endocrine system has been an environmental concern since the early 1990s. To examine these interactions test guidelines have been introduced by regulatory agencies to screen for possible endocrine active compounds. One of these guidelines is the EPA's OPPTS 890.1550 [Steroidogenesis (Human Cell Line‐H295R)]. This guideline requires the quantification of two major biomarkers (testosterone and estradiol) in various biological test systems. Traditional quantitation methodologies such as Radioimmunoassay (RIA) and Enzyme‐linked Immunosorbent Assay (ELISA) have been used to quantify low levels of steroids. However, those methodologies have drawbacks such as the radioactive safety, antibody availability, separate assay for each biomarker, and lack of selectivity. In the current study, a rapid and sensitive liquid chromatography/positive atmospheric pressure photoionization tandem mass spectrometry method (LC/APPI‐MS/MS) has been developed and validated for the simultaneous quantitation of testosterone and estradiol in the H295R cell line. Briefly, the media from cultured cells was extracted with dichloromethane (CH₂Cl₂) containing internal standards of both testosterone‐d₃ and estradiol‐¹³C₃; then, the extracted organic layer was concentrated down to dryness. The final residue was derivatized with dansyl chloride solution, and directly analyzed by LC/APPI‐MS/MS. The calibration curves, with concentration ranging from 10 to 2500 pg/mL, were linear with coefficient >0.99. The lower limits of quantitation for both testosterone and estradiol were 10 pg/mL. This method was successfully validated to support requirements of the current EPA Steroidogenesis guideline. This type of method may also provide value for rapid and precise measurements of these two hormones in other in vitro or in vivo test systems. Copyright © 2011 John Wiley & Sons, Ltd.     

Simultaneous quantitation of testosterone,estradiol, ethinyl estradiol,and 11‐ketotestosterone in fathead minnow fish plasma by liquid chromatography/positive atmospheric pressure photoionization tandem mass spectrometry

In the present work, for the first time, a rapid and sensitive liquid chromatography/positive atmospheric pressure photoionization tandem mass spectrometry (LC/APPI‐MS/MS) method has been developed and validated for the simultaneous quantitation of testosterone, estradiol, ethinyl estradiol, and 11‐ketotestosterone in fathead minnow fish plasma using no more than 10 µL of plasma. Compounds present in plasma were directly derivatized with dansyl chloride and 25 µL of the derivatized mixture was injected into the LC/APPI‐MS/MS system. The gradient chromatographic elution was achieved on an Agilent Zorbax SB‐C18 analytical column (2.1 mm × 50 mm, 1.8 µm particle size) with mobile phases consisting of acetonitrile, water and acetic acid. The flow rate was 0.5 to 0.7 mL/min and the total run time was 11.5 min. The lower limits of quantitation for testosterone, estradiol, ethinyl estradiol, and 11‐ketotestosterone and were 1, 1, 1, and 2.5 ng/mL, respectively. Intra‐batch precision was less than 19.4% and inter‐batch precision was less than 11.7% for all four analytes. Accuracy was within 83.5–115.4% of nominal concentrations. This method is used for quantitation of sex steroid levels in fathead minnow tested in endocrine disruptor screening experiments. Copyright © 2009 John Wiley & Sons, Ltd.     

The physics of diamond

The accurate measurement of the thermal conductivity of metals still poses considerable experimental difficulty. The reasons for this, and the main ways in which the problem has been approached, are summarized. A detailed examination of the development in technique and methods of measurement shows that while most of the steady-state methods introduced over 50 years ago are still being improved, the emphasis in the last few years has been on the development of methods which give more rapid results, particularly at high temperatures.