A comparison of the biological properties of of androst-5-en-3β-ol,a series of (20R)-n-alkylpregn-5-en-3β-ols and 21-isopentylcholesterol with those of cholesterol

The Δ⁵-sterol, androst-5-en-3β-ol, which has no side chain at C-17, did not permit molting of the insectHeliothis zea, growth of either the protozoanTetrahymena pyriformis, or the yeastSaccharomyces cerevisiae adapted to anaerobic conditions, nor was the sterol esterified by a mammalian microsomal ACAT preparation. However, the sterol did form a liposome with egg lecithin and, when fed to mice, did inhibit hepatic cholesterol synthesis. 21-Isopentylcholesterol also formed a liposome but neither supported the growth of the yeast nor was metabolized by the protozoan. When sterols, 20(R)-n-alkylpregn-5-en-3β-ols, with side chains of varying lengths were added to the medium of the protozoan, maximal esterification with fatty acids occurred with the 20(R)-n-pentyl derivative, and maximal inhibition of tetrahymanol formation occurred with then-butyl,n-pentyl andn-hexyl derivatives. In all of the assays, cholesterol showed a positive response, either permitting molting or growth, being metabolized, inhibiting sterol or tetrahymanol synthesis, or forming a liposome.     

Words from "Sesame Street": Learning vocabulary while viewing.

The present study was a longitudinal investigation of preschool children's viewing of "Sesame Street" and their vocabulary development. Five 1-week diaries of television viewing were collected for 2 years from 2 cohorts of children; 1 group was followed from ages 3 to 5 (n?=?160) and another from ages 5 to 7 (n?=?166). Child and family measures included children's vocabulary skills, gender, presence of siblings, parent education, parent encouragement of "Sesame Street" viewing, and parent positive attitudes about television. Cross-age multiple regressions, in conjunction with within-age regressions, suggested a positive effect of "Sesame Street" viewing from ages 3 to 5, with declining benefits from ages 5 to 7. Neither positive nor negative effects were evident for viewing other kinds of children's programs, such as cartoons. Results suggest that the content and presentation formats of "Sesame Street" are well suited to preschoolers' vocabulary development, independent of parent education, family size, child gender, and parental attitudes. The findings suggest the feasibility of tutorial uses of the video medium. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Die neue DAfStb‐Richtlinie “Vorbeugende Maßnahmen gegen schädigende Alkalireaktion im Beton”

The new DAfStb‐Guideline “Preventive Measures against detrimental Alkali‐Reaction in Concrete (Alkali‐Guideline)” In 2002 the German Committee for Structural Concrete decided to revise the Alkali‐Guideline. The motivation for the revision may be summarised as follows: – further developments in the german concrete technology – damage cases in concrete pavements – development of new rapid test methods – further specification of alkali reactive aggregates The contribution gives a detailed overview of the main amendments in the new Guideline and illustrates the background behind the key regulations.     

Ein orthotropes Werkstoffgesetz für Folien

An orthotropic material law for foils. Foils are characterized by an orthotropic load carrying behaviour, which results from the manufacturing process. Normally this orthotropic behaviour is not considered in structural analysis. In the following a theory is described, which allows the determination of any plain stress situation and the test is shown to verify the theory. This is a necessary assumption for a more precise prediction to the load carrying behaviour in membrane structures made of foils.     

Thirty years after Harrison and Saeed: Does the medium make the message?

In 1977, Harrison and Saeed published what became the classic study of personal advertisements. They found that women tended to offer youth and attractiveness, while seeking financial security or wealth. Men, in turn, sought youth and attractiveness, while offering financial security. The purpose of the current study was to determine if changes in the medium used for personal ads (Internet versus print) has had an impact on stated preferences in mate selection. Our results duplicated the Harrison and Saeed (1977) findings, suggesting that neither the medium, nor the societal changes of the last 30 years, have had any effect on mate selection. In a supplementary analysis of women in the 50–69 age group, however, we found that these women were less willing to date older men, preferring younger partners.     

Three-dimensional structure of the zona pellucida at ovulation

The mammalian zona pellucida (ZP) is an extracellular matrix surrounding oocytes and early embryos, which is critical for normal fertilization and preimplantation development. It is made up of three/four glycoproteins arranged in a delicate filamentous matrix. Scanning electron microscopy (SEM) studies have shown that ZP has a porous, net-like structure and/or nearly smooth and compact aspect. In this study, the fine 3-D structure of the human and mouse ZP is reviewed with the aim to integrate ultrastructural and molecular data, considering that the mouse is still used as a good model for human fertilization. By conventional SEM observations, numerous evidences support that the spongy ZP appearance well correlates with mature oocytes. When observed through more sophisticated techniques at high resolution SEM, ZP showed a delicate meshwork of thin interconnected filaments, in a regular alternating pattern of wide and tight meshes. In mature oocytes, the wide meshes correspond to "pores" of the "spongy" ZP, whereas the tight meshes correspond to the compact parts of the ZP surrounding the pores. In conclusion, the traditional "spongy" or "compact" appearance of the ZP at conventional SEM appears to be only the consequence of a prevalence of different arrangements of microfilament networks, according to the maturation stage of the oocyte, and in agreement with the modern supramolecular model of the ZP at the basis of egg-sperm recognition. Despite great differences in molecular characterization of ZP glycoproteins between human and mouse ZP, there are no differences in the 3-D organization of glycoproteic microfilaments in these species.     

Ultrastructural characteristics of human granulosa cells in a coculture system for in vitro fertilization

The use of somatic cells for cocultures during in vitro fertilization (IVF) is currently finalized to obtain a higher number of healthy and viable embryos with a high potential of implantation. Among the different cell lines that can be used as feeder cells for cocultures, granulosa cells (GCs) are autologous cells, safe and easy to recover. The aim of the present study was to analyze the fine structure of human GCs used in a coculture system to evaluate, from a morphodynamic point of view, their role in supporting embryo development. GCs were collected during oocyte pick-up, 36 h after human chorionic gonadotropin administration, from patients undergoing IVF procedures, who had given their informed consent to be included in this protocol. After coculture, GCs were fixed and processed for light microscopy (LM) and transmission electron microscopy (TEM). By LM, GCs appeared as clusters of loosely packed cells, irregularly rounded or polyhedral in shape, varying in diameter from 18 to 25 microm. Mitotic cells, as well as regressing elements (with pyknotic nuclei or dense cytoplasm) and cell fragments were occasionally observed. By TEM, the plasma membrane was irregular due to the presence of cytoplasmic evaginations. Linear and annular gap junctions between neighboring GCs were found. GC nuclei, rounded and eccentrically located, contained finely dispersed chromatin, one (often two) prominent nucleoli and, infrequently, peripheral patches of heterochromatin. Numerous organelles populated the GC cytoplasm, among them, mitochondria were rod-shaped or elongated, usually provided with tubular-vesicular cristae but occasionally showing atypical, longitudinally oriented cristae. Membranes of smooth endoplasmic reticulum, Golgi stacks and vesicles, secretory-like granules, cisternae of rough endoplasmic reticulum (RER), free ribosomes and polysomes, lysosomal-like bodies, microfilaments, and lipid droplets were also seen in the GC cytoplasm. In most cells, RER was scarcely represented and numerous lipid droplets filled the perinuclear space. On the contrary, some GCs contained an abundant RER and rare lipid droplets scattered in the cytoplasm. In conclusion, our data demonstrated the presence, in a coculture system, of GCs provided with ultrastructural characteristics typical of healthy, metabolically active, mostly steroidogenic cells. Protein-synthetic cells have also been detected. These data, evaluated at the light of biochemical and clinical studies, sustain the capability of human GCs cocultures to positively affect early embryo development in vitro by the secretion of steroids and proteins, putative "embryotrophic" factors.