Cell-free apoptosis in Xenopus egg extracts: inhibition by Bcl-2 and requirement for an organelle fraction enriched in mitochondria

Apoptotic cell death involves a ritual series of morphological changes, presumably reflecting a conserved molecular pathway. We now report that the nuclear events typical of apoptosis can be reproduced in "apoptotic" Xenopus egg extracts. In this cell-free system, nuclear assembly and protein import are initially normal; after 2-4 hr, however, a process of nuclear destruction ensues involving chromatin condensation and the shrinkage and fragmentation of the nuclei. This apoptotic process, which also occurs in nuclei added exogenously, is blocked by the addition of baculovirus-expressed Bcl-2 protein. To block the disintegration of nuclei that are added later, Bcl-2 must be present during this latent period. "Apoptosis" in these extracts requires a dense organelle fraction enriched in mitochondria. The cell-free system described here provides a novel tool for understanding intracellular events in apoptosis and the inhibitory function of Bcl-2.     

A candidate recombination modifier gene for Zea mays L

Maize meiotic mutant desynaptic (dy) was tested as a candidate recombination modifier gene because its effect is manifested in prophase I. Recombination rates for desynaptic (dy) and its wild type were compared in two ways: (1) segregation analysis using six linked molecular markers on chromosome 1L and (2) cytogenetic analysis using fluorescence in situ hybridization (FISH)-aided meiotic configurations observed in metaphase I. Chromosome 1L map lengths among the six linked markers were 45-63 cM for five F2 dy/dy plants, significantly lower than the wild-type F2 map distance of 72 cM. Chromosomes 2 and 6 were marked with rDNA FISH probes, and their map lengths were estimated from FISH-adorned meiotic configurations using the expectation-maximization algorithm. Chiasma frequencies for dy/dy plants were significantly reduced for both arms of chromosome 2, for chromosome arm 6L, and for eight unidentified chromosomes. There was a notable exception for the nucleolus-organizing region-bearing arm chromosome arm 6S, where dy increased chiasma frequency. Maize meiotic mutant desynaptic is a recombination modifier gene based on cytogenetic and segregation analyses.     

Requirement for multiple lymphocyte subsets in protection by a live attenuated vaccine against retroviral infection

STUDY DESIGN: A case report and literature review of thoracic hyperkyphosis deformity secondary to glucocorticoid-induced osteoporosis in Cushing's disease. OBJECTIVES: To identify the pathophysiology of glucocorticoid-induced osteoporosis and to outline the diagnosis and treatment options for a patient with severe spinal deformity secondary to unrecognized excess glucocorticoid activity. SUMMARY OF BACKGROUND DATA: Glucocorticoid-induced osteoporosis is seen in patients exposed to supraphysiologic levels of endogenous or exogenously administered glucocorticoids. In these patients, glucocorticoids act to suppress bone formation and increase bone resorption by indirect and direct effects. These patients have a high prevalence of trabecular bone loss, resulting in much higher rates of vertebral body collapse and pathologic fracture and thus causing an increased propensity toward kyphotic spinal malalignment. METHODS: The literature was reviewed and case reports studied. This case report highlights the pathophysiology of the disease process that caused the spinal deformity and the surgical intervention used to correct the kyphotic deformity after the metabolic problem was resolved. RESULTS: This patient has responded well to treatment and surgical intervention to correct a thoracic hyperkyphotic deformity without complication. CONCLUSIONS: Unrecognized endogenous production of glucocorticoids in Cushing's disease should be considered in young adult patients with progressive osteoporotic spinal deformities.     

无色透明新型光纤油膏的研制开发

光纤油膏是光缆中必不可少的新型防水材料，光纤油膏直接与光纤接触，质量指标要求很高．在国内原料无法满足生产高质量的光纤油膏的前提下，用自制的主要原料高吸油性聚合物、抗下垂剂进一步与石油烃、有机增稠剂、无机填料充分混合均匀，制成了析氢值低、油分离小、锥入度大、高低温性能好、指标达到进口指标的光纤油膏．     

Coordinate intracellular expression of Salmonella genes induced during infection

Salmonella typhimurium in vivo-induced (ivi) genes were grouped by their coordinate behavior in response to a wide variety of environmental and genetic signals, including pH, Mg2+, Fe2+, and PhoPQ. All of the seven ivi fusions that are induced by both low pH and low Mg2+ (e.g., iviVI-A) are activated by the PhoPQ regulatory system. Iron-responsive ivi fusions include those induced under iron limitation (e.g., entF) as well as one induced by iron excess but only in the absence of PhoP (pdu). Intracellular expression studies showed that each of the pH- and Mg2+-responsive fusions is induced upon entry into and growth within three distinct mammalian cell lines: RAW 264.7 murine macrophages and two cultured human epithelial cell lines: HEp-2 and Henle-407. Each ivi fusion has a characteristic level of induction consistent within all three cell types, suggesting that this class of coordinately expressed ivi genes responds to general intracellular signals that are present both in initial and in progressive stages of infection and may reflect their responses to similar vacuolar microenvironments in these cell types. Investigation of ivi expression patterns reveals not only the inherent versatility of pathogens to express a given gene(s) at various host sites but also the ability to modify their expression within the context of different animal hosts, tissues, cell types, or subcellular compartments.     

Association of human leucocyte antigen phenotype with vaccine efficacy in patients receiving vaginal mucosal immunization for recurrent urinary tract infection

CONTEXT: One or both commercial tuberculin skin test reagents (Aplisol and Tubersol) may have a high rate of false-positive reactions. OBJECTIVE: To compare the reaction size and specificity of skin testing with Aplisol, Tubersol, and the standard purified protein derivative (PPD-S1). DESIGN: Double-blind trial, conducted between May 14, 1997, and October28, 1997, in which each individual received 4 tuberculin skin reagents at sites assigned at random. SETTING: Health departments and universities in 6 US cities. PARTICIPANTS: A total of 1555 persons at low risk of latent tuberculosis infection. INTERVENTION: Simultaneous skin tests with Aplisol, Tubersol, PPD-S1, and either a second PPD-S1 or PPD-S2 (a proposed new standard). MAIN OUTCOME MEASURE: Reaction size at each injection site measured by 2 investigators blinded to type of reagent. RESULTS: Aplisol produced slightly larger reactions than Tubersol, but this difference did not significantly change skin test interpretation. The mean +/- SD reaction sizes were 3.4+/-4.2 mm with Aplisol, 2.1+/-3.2 mm with Tubersol, and 2.5+/-3.6 mm with PPD-S1. Assuming that all participants were uninfected and using a 10-mm cutoff, the specificities of the tests were high: Aplisol, 98.2%; Tubersol, 99.2%; and PPD-S1, 98.9%. Significant variability was not detected in interobserver, host, and lot-to-lot reagent comparisons. CONCLUSION: Using a cutoff of at least 10 mm, testing with 3 different PPD reagents resulted in similar numbers of uninfected persons being correctly classified.     

Errors made by animals in memory paradigms are not always due to failure of memory

It is commonly assumed that errors in animal memory paradigms such as delayed matching to sample, radial mazes, and food-cache recovery are due to failures in memory for information necessary to perform the task successfully. A body of research, reviewed here, suggests that this is not always the case: animals sometimes make errors despite apparently being able to remember the appropriate information. In this paper a case study of this phenomenon is described, along with a demonstration of a simple procedural modification that successfully reduced these non-memory errors, thereby producing a better measure of memory.     

Management of hysteroscopic surgery complications

Hysteroscopic surgery is considered a safe, routine gynecologic procedure performed in the OR and in office settings. Complications are rare; however, when complications do occur they can be severe and rapid. The surgical team members must understand the significance of patient monitoring and proper equipment operation to ensure positive patient outcomes. This article discusses complications from intravasation of various distending media used during hysteroscopy and the complication of hyponatremia. A physiologic approach to these problems enhances awareness of the significance of patient monitoring during hysteroscopic procedures.