Pathology of ocular irritation with bleaching agents in the rabbit low-volume eye test.
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Despite differences in the processes leading to tissue damage, the ocular irritation response to various surfactants, two concentrations of an acid and an alkali, and an acetone, alcohol, aromatic amine, and aldehyde has been shown to depend on the extent of initial injury. The purpose of this study was to assess the extent to which this fundamental relationship exists for bleaching agents in the rabbit low-volume eye test. Ten microl of sodium perborate monohydrate (NaBO3), sodium hypochlorite (NaOCl), 10% hydrogen peroxide (H2O2), and 15% H2O2 was applied directly to the cornea of the right eye of each rabbit. Macroscopic assessments for irritation were made 3 hours after dosing and periodically until 35 days. Light microscopic examinations were conducted on tissues obtained at 3 hr and on 1, 3, and 35 days. In vivo confocal microscopy (CM) and measurements of dead corneal epithelial cells and keratocytes at 3 hours and 1 day were used to characterize quantitatively initial corneal injury, while in vivo CM performed at 3 hours and 1, 3, 7, 14, and 35 days was used to characterize quantitatively the corneal changes over time. The changes with NaBO3 and NaOCl were consistent with mild irritancy. For both, corneal injury was limited to the epithelium and superficial stroma. The changes with 10% H202 and 15% H2O2 were consistent with severe irritation. Both concentrations affected the epithelium and deep stroma, with 15% H2O2 also at times affecting the endothelium. However, unlike other irritants previously studied, with 10% H2O2 and 15% H2O2 there was an incongruity between the extent of epithelial and stromal injury, with stromal injury being more extensive than epithelial injury. A similar, although less dramatic, effect was observed with NaBO3. Additionally, there was still significant keratocyte loss at 35 days with 10% H2O2 and 15% H2O2 even though the eyes at times were considered to be macroscopically normal. These observations highlight the need to include both epithelial and stromal components in an ex vivo or in vitro alternative assay. In conclusion, these results continue to support and extend our hypothesis that ocular irritation is principally defined by the extent of initial injury despite clear differences in the means by which irritants cause tissue damage. Importantly, we have identified unique differences in the ocular injury and responses occurring with bleaching agents that are important to consider in the development and validation of alternative ocular irritation tests to characterize a broad range of materials differing in type and irritancy. (+info)
Antitumor beta glucan from the cultured fruit body of Agaricus blazei.
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Agaricus blazei is a medically important mushroom widely eaten and prescribed in Japan. Polysaccharide fractions were prepared from cultured A. blazei by repeated extraction with hot water (AgHWE), cold NaOH (AgCA), and then hot NaOH (AgHA). By chemical, enzymic, and NMR analyses, the primary structures of AgHWE, AgCA, and AgHA were mainly composed of 1,6-beta-glucan. Among these fractions, the NaOH extracts showed antitumor activity against the solid form of Sarcoma 180 in ICR mice. To demonstrate the active component in these fractions, several chemical and enzymic treatments were applied. These fractions were found to be i) neutral beta-glucan passing DEAE-Sephadex A-25, ii) resistant to periodate oxidation (I/B) and subsequent partial acid hydrolysis (I/B/H), iii) resistant to a 1,3-beta-glucanase, zymolyase, before I/B, but sensitive after I/B/H. In addition, after I/B/H treatment of the neutral fraction of AgCAE, a signal around 86 ppm attributable to 1,3-beta glucosidic linkage was detectable in the 13C-NMR spectrum. These facts strongly suggest that a highly branched 1,3-beta-glucan segment forms the active center of the antitumor activity. (+info)
Collaboration, cholera, and cyclones: a project to improve point-of-use water quality in Madagascar.
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In November 1999, CARE Madagascar, Population Services International (PSI), and the Centers for Disease Control and Prevention (CDC) selected 30 poor communities in urban Antananarivo as the target population for launch of the Safe Water System. The system consists of behavior change techniques along with point-of-use treatment and safe storage of water. The project was launched in March 2000, ahead of schedule, because a cholera epidemic struck Madagascar in January. Because of the enormous demand created by the cholera epidemic and by 3 cyclones that followed in the next 3 months, the project grew to national scale in less than a year. The combination of community mobilization and social marketing resulted in increased demand for and use of the Safe Water System. (+info)
Cell wall architecture of the elongating maize coleoptile.
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The primary walls of grasses are composed of cellulose microfibrils, glucuronoarabinoxylans (GAXs), and mixed-linkage beta-glucans, together with smaller amounts of xyloglucans, glucomannans, pectins, and a network of polyphenolic substances. Chemical imaging by Fourier transform infrared microspectroscopy revealed large differences in the distributions of many chemical species between different tissues of the maize (Zea mays) coleoptile. This was confirmed by chemical analyses of isolated outer epidermal tissues compared with mesophyll-enriched preparations. Glucomannans and esterified uronic acids were more abundant in the epidermis, whereas beta-glucans were more abundant in the mesophyll cells. The localization of beta-glucan was confirmed by immunocytochemistry in the electron microscope and quantitative biochemical assays. We used field emission scanning electron microscopy, infrared microspectroscopy, and biochemical characterization of sequentially extracted polymers to further characterize the cell wall architecture of the epidermis. Oxidation of the phenolic network followed by dilute NaOH extraction widened the pores of the wall substantially and permitted observation by scanning electron microscopy of up to six distinct microfibrillar lamellae. Sequential chemical extraction of specific polysaccharides together with enzymic digestion of beta-glucans allowed us to distinguish two distinct domains in the grass primary wall. First, a beta-glucan-enriched domain, coextensive with GAXs of low degrees of arabinosyl substitution and glucomannans, is tightly associated around microfibrils. Second, a GAX that is more highly substituted with arabinosyl residues and additional glucomannan provides an interstitial domain that interconnects the beta-glucan-coated microfibrils. Implications for current models that attempt to explain the biochemical and biophysical mechanism of wall loosening during cell growth are discussed. (+info)
Improving sensitivity of direct microscopy for detection of acid-fast bacilli in sputum: use of chitin in mucus digestion.
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In order to try to improve the results of direct smear microscopy, we used the mucus-digesting quality of chitin in tuberculosis (TB) laboratories. For this purpose, a total of 430 sputum specimens were processed by the N-acetyl-L-cysteine concentration, sodium hypochlorite (NaOCl) liquefaction, chitin sedimentation, and direct microscopy methods. Then, the smear sensitivity for acid-fast bacillus detection by chitin-treated sputum was compared with the sensitivity of smears prepared by other methods. Our results showed that the chitin solution took less time to completely homogenize the mucoid sputum than did the N-acetyl-L-cysteine and NaOCl methods. The N-acetyl-L-cysteine concentration method demonstrated sensitivity and specificity levels of 83 and 97%, respectively. In comparison, the sensitivity of chitin sedimentation was 80%, with a specificity of 96.7%. The NaOCl liquefaction method showed a sensitivity of 78%, with a specificity of 96%. Finally, the sensitivity of direct microscopy was lower than those of the other tested methods and was only 46%, with a specificity of 90%. The chitin and NaOCl liquefaction methods are both easy to perform, and they do not require additional equipment (centrifuges). Also, our results demonstrated that the chitin method is less time-consuming than the NaOCl method, since only 30 min of incubation is required to bring complete sedimentation of bacilli in chitin-treated sputum whereas the NaOCl method needs 10 to 12 h to give the same results in the same sputum specimens. Therefore, the chitin liquefaction and sedimentation method may provide better results in TB laboratories of developing countries than the N-acetyl-L-cysteine concentration, NaOCl overnight sedimentation, and direct smear microscopy methods. (+info)
Preventing infection from reusable medical equipment: a systematic review.
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BACKGROUND: In 2000, the World Health Organization (WHO) had eight sets of conflicting recommendations for decontaminating medical equipment. We conducted a systematic review of observational studies to assist WHO in reconciling the various guidelines. This paper summarises the methods developed and illustrates the results for three procedures--alcohol, bleach and povidone iodine. METHODS: We developed a Medline search strategy and applied inclusion criteria specifying the decontamination procedures of interest and an outcome of microbial destruction for a set of marker organisms. We developed protocols to assess the quality of studies and categorised them according to the reliability of the methods used. Through an iterative process we identified best practice for the decontamination methods and key additional factors required to ensure their effectiveness. We identified 88 published papers for inclusion, describing 135 separate studies of decontamination. RESULTS: For disinfection with alcohol, best practice was identified from 23 studies as an exposure to 70-80% ethanol or isopropanol for at least 5 minutes. Bleach was effective for sterilization at a concentration of 5000 ppm for 5 minutes and for disinfection at 1000 ppm for 10 minutes (33 studies). Povidone iodine was only partially effective for disinfection at a concentration of 1% for 15 minutes (15 studies). CONCLUSIONS: Our findings provide an evidence base for WHO guidelines on decontaminating medical equipment. The results support the recommended use of bleach and show that alcohol could be used more widely than current guidelines suggest, provided best practice is followed. The effectiveness of povidone iodine is uncertain. (+info)
Efficacy of common laboratory disinfectants on the infectivity of Cryptosporidium parvum oocysts in cell culture.
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Nine liquid disinfectants were tested for their ability to reduce infectivity of Cryptosporidium parvum oocysts in cell culture. A 4-min exposure to 6% hydrogen peroxide and a 13-min exposure to ammonium hydroxide-amended windshield washer fluid reduced infectivity 1,000-fold. Other disinfectants tested (70% ethanol, 37% methanol, 6% sodium hypochlorite, 70% isopropanol, and three commercial disinfectants) did not reduce the infectivity after a 33-min exposure. The results indicate that hydrogen peroxide and windshield washer fluid or ammonium hydroxide disinfectant may be suitable laboratory disinfectants against C. parvum oocysts. (+info)
Suppression of the TNFalpha-induced increase in IL-1alpha expression by hypochlorite in human corneal epithelial cells.
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PURPOSE: In response to injury, activated neutrophils release tumor necrosis factor (TNF)-alpha and myeloperoxidase (MPO). TNFalpha in turn causes human corneal epithelial cells to secrete interleukin (IL)-1alpha, whereas MPO results in formation of HClO/OCl(-). The effect of HClO/OCl(-) on the expression of the IL-1alpha gene and protein is unknown. The current study was undertaken to examine in immortalized human corneal epithelial cells whether NaOCl alters TNFalpha-induced increases in expression of IL-1alpha gene and protein. METHODS: Semiquantitative RT-PCR and ELISA characterized IL-1alpha gene and protein expression, respectively. TNFalpha-induced nuclear transfer of nuclear factor (NF)-kappaB was measured by electrophoretic mobility shift assay (EMSA). The alpha isoform of inhibitory protein kappaB (IkappaBalpha) was identified by Western blot analysis. RESULTS: Exposure to NaOCl (0.75 mM) for 10 minutes caused suppression of TNFalpha-induced increases in IL-1alpha mRNA and protein, declines in NFkappaB nuclear transfer, and a modification of IkappaBalpha, based on a bandshift detected by Western blot analysis. Modified IkappaBalpha became resistant to TNFalpha-induced proteolysis. Methionine sulfoxide reductase A (MsrA, 10 micro M) eliminated the NaOCl-induced IkappaBalpha bandshift. CONCLUSIONS; NaOCl oxidizes IkappaBalpha at methionine residues and thereby suppresses dissociation of IkappaBalpha from NFkappaB. Decreased dissociation could in turn suppress TNFalpha-induced activation of NFkappaB, resulting in declines in expression of IL-1alpha gene and protein. These effects suggest that release of HClO/OCl(-) in vivo by activated neutrophils may counterbalance TNFalpha-induced NFkappaB-dependent secretion if IL-1alpha and suppress an excessive inflammatory reaction. (+info)