Dissociation of intracellular lysosomal rupture from the cell death caused by silica

The relationship between intracellular lysosomal rupture and cell death caused by silica was studied in P388d(1) macrophages. After 3 h of exposure to 150 μg silica in medium containing 1.8 mM Ca(2+), 60 percent of the cells were unable to exclude trypan blue. In the absence of extracellular Ca(2+), however, all of the cells remained viable. Phagocytosis of silica particles occurred to the same extent in the presence or absence of Ca(2+). The percentage of P388D(1) cells killed by silica depended on the dose and the concentration of Ca(2+) in the medium. Intracellular lyosomal rupture after exposure to silica was measured by acridine orange fluorescence or histochemical assay of horseradish peroxidase. With either assay, 60 percent of the cells exposed to 150 μg silica for 3 h in the presence of Ca(2+) showed intracellular lysosomal rupture, was not associated with measureable degradation of total DNA, RNA, protein, or phospholipids or accelerated turnover of exogenous horseradish peroxidase. Pretreatment with promethazine (20 μg/ml) protected 80 percent of P388D(1) macrophages against silica toxicity although lysosomal rupture occurred in 60-70 percent of the cells. Intracellular lysosomal rupture was prevented in 80 percent of the cells by pretreatment with indomethacin (5 x 10(-5)M), yet 40-50 percent of the cells died after 3 h of exposure to 150 μg silica in 1.8 mM extracellular Ca(2+). The calcium ionophore A23187 also caused intracellular lysosomal rupture in 90-98 percent of the cells treated for 1 h in either the presence or absence of extracellular Ca(2+). With the addition of 1.8 mM Ca(2+), 80 percent of the cells was killed after 3 h, whereas all of the cells remained viable in the absence of Ca(2+). These experiments suggest that intracellular lysosomal rupture is not causally related to the cell death cause by silica or {"type":"entrez-nucleotide","attrs":{"text":"A23187","term_id":"833253","term_text":"A23187"}}A23187. Cell death is dependent on extracellular Ca(2+) and may be mediated by an influx of these ions across the plasma membrane permeability barrier damaged directly by exposure to these toxins.     

Paracrine effects of oocyte secreted factors and stem cell factor on porcine granulosa and theca cells <Emphasis Type="Italic">in vitro</Emphasis>

Oocyte control of granulosa and theca cell function may be mediated by several growth factors via a local feedback loop(s) between these cell types. This study examined both the role of oocyte-secreted factors on granulosa and thecal cells, cultured independently and in co-culture, and the effect of stem cell factor (SCF); a granulosa cell derived peptide that appears to have multiple roles in follicle development. Granulosa and theca cells were isolated from 2–6 mm healthy follicles of mature porcine ovaries and cultured under serum-free conditions, supplemented with: 100 ng/ml LR3 IGF-1, 10 ng/ml insulin, 100 ng/ml testosterone, 0–10 ng/ml SCF, 1 ng/ml FSH (granulosa), 0.01 ng/ml LH (theca) or 1 ng/ml FSH and 0.01 ng/ml LH (co-culture) and with/without oocyte conditioned medium (OCM) or 5 oocytes. Cells were cultured in 96 well plates for 144 h, after which viable cell numbers were determined. Medium was replaced every 48 h and spent medium analysed for steroids.     

Phylogenetic analysis of the tenascin gene family: evidence of origin early in the chordate lineage

Background  

Tenascins are a family of glycoproteins found primarily in the extracellular matrix of embryos where they help to regulate cell proliferation, adhesion and migration. In order to learn more about their origins and relationships to each other, as well as to clarify the nomenclature used to describe them, the tenascin genes of the urochordate Ciona intestinalis, the pufferfish Tetraodon nigroviridis and Takifugu rubripes and the frog Xenopus tropicalis were identified and their gene organization and predicted protein products compared with the previously characterized tenascins of amniotes.     

Phase transition in superdense hydrogen and deuterium

Results are presented from numerical simulations of the thermodynamic properties of superdense hydrogen and deuterium plasmas by the Monte Carlo method and from calculations by a multicomponent chemical model. The results obtained reveal the anomalous behavior of the thermodynamic functions and composition of molecular gas plasmas in the submegabar and megabar pressure ranges. Such behavior is interpreted as a dissociative phase transition. The results of calculations by the chemical model are compared with the experimental data on the equation of state and conductivity of hydrogen and deuterium plasmas.     

Transfer RNA genes in the cap-oxil region of yeast mitochondrial DNA.

A cytoplasmic "petite" (rho-) clone of Saccharomyces cerevisiae has been isolated and found through DNA sequencing to contain the genes for cysteine, histidine, leucine, glutamine, lysine, arginine, and glycine tRNAs. This clone, designated DS502, has a tandemly repeated 3.5 kb segment of the wild type genome from 0.7 to 5.6 units. All the tRNA genes are transcribed from the same strand of DNA in the direction cap to oxil. The mitochondrial DNA segment of DS502 fills a sequence gap that existed between the histidine and lysine tRNAs. The new sequence data has made it possible to assign accurate map positions to all the tRNA genes in the cap-oxil span of the yeast mitochondrial genome. A detailed restriction map of the region from 0 to 17 map units along with the locations of 16 tRNA genes have been determined. The secondary structures of the leucine and glutamine tRNAs have been deduced from their gene sequences. The leucine tRNA exhibits 64% sequence homology to an E. coli leucine tRNA.     

Synthesis of Apolipoprotein A-1 in Pig Brain Microvascular Endothelial Cells

In an approach toward the identification of hitherto unknown proteins involved in the function of the blood-brain barrier, we constructed a pig brain microvessel-derived cDNA library that is enriched in blood-brain barrier specific sequences by means of subtractive cloning. Sequence analysis of selected clones revealed that one of the cDNAs encoded porcine apolipoprotein (apo) A-1. The identity of apo A-1 mRNA was further confirmed by in vitro translation of RNA from brain microvascular endothelial cells and subsequent immunoprecipitation with an antibody against human apo A-1. We further investigated the expression of apo A-1 mRNA in several tissues and in endothelial cells of the pig. It is shown that cultured brain microvascular endothelial cells provide an in vitro model to study the expression and function of apo A-1 in the microvasculature of the brain.     

Assembly of the mitochondrial membrane system. Physical map of the Oxi3 locus of yeast mitochondrial DNA

The oxi3 locus of yeast mitochondrial DNA is currently thought to code for Subunit 1 of cytochrome oxidase (Tzagoloff, A., Macino, G., and Sebald, W. (1979) Annu. Rev. Biochem. 48, 419-441). The respiratory competent strain of Saccharomyces cerevisiae D273-10B/A48 was used to obtain cytoplasmic "petite" clones enriched for genetic markers in the oci3 locus. The most complex clone studied (DS6) was ascertained to have a mitochondrial genome with a tandemly repeated segment of mtDNA 16.5 kilobases in length. The oxi3 locus was dissected by mutagenesis of DS6 with ethidium bromide and selection of new clones having less complex genotypes. Six derivative clones with genome sizes ranging from 2.3 to 6.1 kilobases have been extensively analyzed. Most of the restriction sites present in the segments of mtDNA retained by the clones have been mapped, thereby providing a detailed restriction map of the oxi3 gene. Based on the physical locations of the most distal oxi3 mutations, the gene spans approximately 10,000 nucleotides and occupies the region of wild type mtDNA from 44 to 58 map units.     

Expression of biologically active,mature human granulocyte-macrophage colony stimulating factor with anE. coli secretory expression system

Human granulocyte-macrophage colony stimulating factor (HuGM-CSF) was expressed periplasmically inEscherichia coli with the secretory vector, pINIIIompA2 [10]. HuGM-CSF protein thus expressed was shown to be faithfully cleaved and biologically active. This protein, however, could not be released by osmotic shock and, on subcellular fractionation, co-sedimented with the outer membrane fraction. The effect of promoters, vectors, host strains, induction conditions and media formulation on expression levels was also evaluated. Some of these factors play a significant role in determining maximal achievable levels of HuGM-CSF in the secretory expression system ofE. coli.Both may be considered first authors.     

Epidemiology of training injuries in amateur taekwondo athletes: a retrospective cohort study

The objectives of this study were to estimate the incidence and describe the pattern and severity of training injuries in taekwondo, and to compare pattern and severity of training injuries with competition injuries. One hundred and fifty-two active Australian amateur taekwondo athletes, aged 12 years or over, completed an online survey comprising questions on training exposure and injury history over the preceding 12 months. The main outcome measures were: overall injury incidence rate per athlete-year; training injury incidence rate per athlete-year, per 1000 athlete-training-sessions, and per 1000 athlete-hours of training; injury severity; and injury proportions by anatomical region and by type of injury. Injury incidence rates were calculated with 95% confidence intervals using standard methods, while injury proportions were compared using Fisher''s exact test. The vast majority (81.5%) of taekwondo injuries in an average athlete-year occurred during training. The training injury incidence rate was estimated to be 1.6 (95% CI: 1.4, 1.9) per athlete-year, 11.8 (95% CI: 10.4, 13.4) per 1000 athlete-training-sessions, and 7.0 (95% CI: 6.1, 7.9) per 1000 athlete-hours of training. Among athletes with five or fewer injuries, the severity and injury pattern of training injuries were, by and large, the same as for competition injuries. Approximately sixty percent (60.3%) of training injuries required treatment by a health professional. Considering the burden of training injuries exceeds that of competition injuries, taekwondo governing bodies and stakeholders are encouraged to devote more efforts towards the identification of risk factors for, and prevention of, training injuries in the sport of taekwondo.     

Cell polarity during wound healing in an insect epidermis

The insect integument displays uniform posterior orientation of cuticular denticles or bristles formed by the epidermal cells. We want to understand how cell polarities become uniformly oriented in the plane of the epidermal sheet. Here we test whether directed cell migration disturbs the orientation of denticles. Burning a circular area of epidermal cells beneath the cuticle causes cells to migrate into the resulting wound and the cuticle pattern observed after the subsequent moult depends on the time interval between burning and ecdysis. After a short wound-healing period cuticular protrusions tend to point away from the wound. With increasing would healing periods they tend to point more and more towards the wound centre. These results suggest that the migrating cells tend to orient cuticular protrusions in the direction of cell movement while continued cell movement will bend nascent cuticular protrusions outwards. Cell shape may also determine denticle orientation. I propose that the asymmetric localization of cell components known to determine the orientation of cell migration may also determine denticle orientation in insect epidermal cells.