The Impact of Community Diversity and Consolidated Inequality on Dropping Out of High School

Abstract: Data from the National Education Longitudinal Study were combined with census data at the zip code level to examine the impact of neighborhood racial and ethnic diversity and consolidated inequality, in addition to individual, family, and school factors, on the likelihood of dropping out of high school. Results indicate that while the effects for diversity and consolidated inequality did not support the stated hypotheses, main effects for family risk and prior academic achievement were significant and in the stated direction. Also, when controlling for individual, family, school, and neighborhood characteristics, African Americans were less likely than White students to drop out of school. Implications for contextual effects research and educational outcomes are discussed.     

Mechanism for homologous downregulation of thromboxane A2 receptors in cultured human chronic myelogenous leukemia (K562) cells.

Desensitization of the biologic response to thromboxane A2 (TXA2) mimetics has been observed ex vivo in human platelets due to TXA2 receptor uncoupling and downregulation. To define more clearly the mechanisms of homologous TXA2 receptor downregulation, the effects of the TXA2 mimetics U44069 ([15S)-hydroxy-9,11- (epoxymethano) prostadienoic acid] and I-BOP ([1S-(1 alpha 2 beta(5Z),3 alpha(1E,3S),4 alpha))-7-[3-(3-hydroxy-4- (p-iodophenoxy)-1-butenyl)-7-oxabicyclo[2.2.1]heptan-2-yl]-5 -heptenoic acid) on receptor-mediated calcium fluxes and on ligand binding to TXA2 receptors were studied in the K562 cultured human leukemic cell line which possesses many platelet characteristics. Incubation with U44069 resulted in a time-dependent decrease in the amplitude of TXA2 receptor-mediated intracellular free calcium transients. Under the same conditions, binding of [125I] BOP demonstrated a concurrent loss of K562 plasma membrane binding sites to approximately one-third the original number. The loss of [125I]BOP binding was prevented by coincubation with the TXA2 antagonist SQ29548 ([1S-1 alpha,2 beta (5Z), 3 beta,4 alpha]-7- (3-[2-[phenylamino)-carbonyl) hydrazino) methyl)-7-oxabicyclo-(2.2.1)- heptan-2-yl)-5-heptenoic acid]) and was reversed upon removal of U44069 from the culture medium. SQ29548 alone had no affect on receptor density or affinity. Loss of surface receptors was demonstrated to be mediated by agonist-occupied receptor internalization which was inhibited by incubation at 4 degrees C and did not occur with antagonist occupation. The results indicate that homologous downregulation of TXA2 receptors in K562 cells occurs by agonist-mediated active internalization of plasma membrane TXA2 receptors.     

Invasion of Human Oral Epithelial Cells by Prevotella intermedia

Invasion of oral epithelial cells by pathogenic oral bacteria may represent an important virulence factor in the progression of periodontal disease. Here we report that a clinical isolate of Prevotella intermedia, strain 17, was found to invade a human oral epithelial cell line (KB), whereas P. intermedia 27, another clinical isolate, and P. intermedia 25611, the type strain, were not found to invade the cell line. Invasion was quantified by the recovery of viable bacteria following a standard antibiotic protection assay and observed by electron microscopy. Cytochalasin D, cycloheximide, monodansylcadaverine, and low temperature (4°C) inhibited the internalization of P. intermedia 17. Antibodies raised against P. intermedia type C fimbriae and against whole cells inhibited invasion, but the anti-type-C-fimbria antibody inhibited invasion to a greater extent than the anti-whole-cell antibody. This work provides evidence that at least one strain of P. intermedia can invade an oral epithelial cell line and that the type C fimbriae and a cytoskeletal rearrangement are required for this invasion.     

Pharmacotherapy of psychiatric emergencies

The psychiatric emergency service has become a major provider of psychiatric care over the past decade. Concomitant with this growth has been an emphasis on pharmacological treatment. While rapid tranquilization is the best known and most frequently used intervention, a growing diagnostic awareness has led to a variety of other chemotherapeutic approaches. The current reviews of pharmacologic intervention in the psychiatric emergency service do not detail the variability of treatment approaches or examine alternative treatment approaches. The goal of this article is to critically review current pharmacologic treatments and address areas in which there is no consensus in treatment approach. From this review the authors suggest guidelines for pharmacotherapy of psychiatric emergencies. The authors discuss rapid tranquilization, the treatment of alcohol and drug intoxication and withdrawal, and anxiety disorders.     

Immunohistochemical localization of L-ornithine decarboxylase in developing rat brain

L-Ornithine decarboxylase, the rate limiting enzyme of polyamine biosynthesis and a marker enzyme of tissue proliferation and maturation, was localized immunocytochemically in the developing rat central nervous system. It can be noted that the distribution of the enzyme protein underlies temporal alterations. Conclusions are drawn from the localization of the enzyme and possible functional roles played by ornithine decarboxylase in discrete brain areas.     

Kryokonservierung und Transplantation von Ovarialgewebe

There are relatively few effective clinical options for preserving female fertility, particularly following aggressive chemotherapy and/or radiotherapy treatment protocols. This document reviews scientific background, current technology, clinical results, and potential future applications of ovarian tissue cryopreservation and transplantation. The technology is investigational although rapidly evolving, and the list of appropriate indications may be expanded in the future. Germany stays abreast of these rapid worldwide developments by having founded the first German network of experts for fertility preservation in patients undergoing chemotherapy and/or radiotherapy.