High-precision fluorescence assay for sphingomyelinase activity of isolated enzymes and cell lysates.
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Sphingomyelinases are important enzymes of signal transduction. They catalyze the hydrolysis of sphingomyelin, giving rise to the intracellular formation of biologically active ceramide and phosphatidylcholine. Here we report on a fluorescence method for the fast and accurate determination of this enzyme in biological samples. The assay is based on a fluorescent sphingomyelin analog carrying fluorescent 7-nitro-2-1,3-benzooxadiazolyl amino-dodecanoic acid instead of an aliphatic acyl chain at the nitrogen atom. The fluorescent substrate is hydrolysed by sphingomyelinases to form fluorescent ceramide, which can be separated from the remaining substrate using TLC on silica gel. The fluorescence intensity pattern obtained on the TLC plate can accurately be determined using a CCD camera. Typically, a large number of samples can be analyzed simultaneously. Examples for the quantitative analysis of sphingomyelinases from freshly prepared cellular homogenates as well as from commercial sources are given. (+info)
Comparison of embryonated chicken eggs with MDCK cell culture for the isolation of swine influenza virus.
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Embryonated chicken eggs (ECE) and the Madin-Darby canine kidney (MDCK) cell line were compared for isolation of swine influenza virus (SIV) from nasal swabs and tissue samples. Samples originated from 30 pigs experimentally inoculated with 2 x 106 to 2 x 10(7) embryo infectious dose 50% (EID50)/mL of swine influenza strain A/Swine/Indiana/1726/88 (H1N1). The results were analyzed with McNemar's chi-squared test for symmetry. The results indicated that more samples were SIV-positive with ECE than with tissue culture (P < 0.001), suggesting that ECE remains the system of choice for isolation of SIV. It is recommend that routine use of both SIV isolation systems will increase the sensitivity of detection of virus shedding by considering the differences in growth and tropism of diverse SIV strains. (+info)
Increasing quinolone resistance in Salmonella enterica serotype Enteritidis.
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Until recently, Salmonella enterica serotype Enteritidis has remained sensitive to most antibiotics. However, national surveillance data from Denmark show that quinolone resistance in S. Enteritidis has increased from 0.8% in 1995 to 8.5% in 2000. These data support concerns that the current use of quinolone in food animals leads to increasing resistance in S. Enteritidis and that action should be taken to limit such use. (+info)
Treatment of Salmonella-Arizona-infected turtle eggs with terramycin and chloromycetin by the temperature-differential egg dip method.
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Attempts to eliminate Salmonella and Arizona infection from newly hatched turtles were made by dipping fresh eggs in cold solutions of Terramycin and Chloromycetin at 1,000, 1,200, 1,500 and 2,000 mug per ml for either 10, 20, or 30 min. Control groups consisted of hatchings produced from nondipped eggs or eggs dipped in chilled water. In two of the four experiments 5 to 10 eggs were blended on days 15, 30, and 45 post antibiotic dip treatment. Twenty-five to 60 hatchlings from each control or experimental dip groups were held in containers and the water was tested (excretion method) for Salmonella and Arizona every 15 or 30 days for 180 to 210 days after hatching. Representative turtles were homogenized (blending method) to determine if systemic infections were present. All specimens tested were enriched in tetrathionate and selenite cystine broth. Nondipped eggs and water-dipped eggs routinely showed Salmonella and Arizona present in egg homogenate and hatchlings emerging from these eggs excreted these pathogens. Terramycin- and Chloromycetin-dipped eggs were uniformly negative for these pathogens, only if fresh eggs were dipped. Bacteriological assay of container water and whole turtle homogenate from hatchlings were negative for Salmonella and Arizona if eggs were dipped in 1,000 mug of Terramycin early in the egg laying season or if eggs were dipped in 1,500 or 2,000 mug of Terramycin per ml late in the egg laying season. The results of temperature-differential egg dip studies suggest that this is a feasible and promising method by which to eradicate Salmonella and Arizona from the turtle. (+info)
Chromium supplementation can alleviate negative effects of heat stress on egg production, egg quality and some serum metabolites of laying Japanese quail.
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This study was conducted to determine the effects of Cr (chromium picolinate, CrPic) supplementation at various levels (0, 200, 400, 800 or 1200 microg/kg of diet) on egg production, egg quality and serum concentrations of insulin, corticosterone and glucose in laying Japanese quail (Coturnix coturnix japanica) reared under conditions of heat stress (32.5 degrees C). Laying Japanese quail (n = 150; 45 d old) were divided into five groups of 30 birds. The quail were fed either a control diet containing 965 microg Cr/kg diet or the control diet supplemented with 200, 400, 800 or 1200 microg of Cr/kg diet. Increased supplemental chromium increased body weight (P = 0.05, linear), feed intake (P = 0.05, linear), egg production (P = 0.01, linear) and also improved feed efficiency (P = 0.01, linear). Increased supplemental chromium linearly increased egg weight (P = 0.01), eggshell thickness, egg specific gravity (P = 0.05) and Haugh unit (P = 0.01). Serum insulin concentration increased linearly (P = 0.01), whereas corticosterone and glucose concentration decreased linearly (P = 0.05) as dietary chromium increased. The best results were obtained with 1200 microg Cr/kg diet, and chromium supplementation at such a level can be considered to be protective management practice in a quail diet, reducing the negative effects of heat stress. (+info)
Risk factors for sporadic infection with Salmonella enteritidis, Denmark, 1997-1999.
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In a prospective case-control study of sporadic Salmonella Enteritidis infection in Denmark (1997-1999), foreign travel was reported by 25% of 455 case patients and 8% of 507 controls (odds ratio (OR) = 3.7, 95% confidence interval (CI): 2.4, 5.5). Among nontravelers, 80% of 335 cases and 81% of 467 controls had consumed eggs or dishes containing raw or undercooked eggs during the week before disease onset or interview, while 35% of cases and 19% of controls had incurred this exposure the day before onset or interview (OR = 2.2, 95% CI: 1.5, 3.1). Specific exposures included consumption of buttermilk dessert (OR = 11.7), homemade ice cream (OR = 4.3), raw eggs (OR = 3.4), and eggs fried "sunny side up" (OR = 2.5). Among persons who had used eggs in the week before disease onset or interview, eggs from battery laying hens were associated with disease (white eggs: OR = 2.4, brown eggs: OR = 1.9), whereas consumption of pasteurized eggs tended to be protective (OR = 0.3). The study confirmed that eggs are the principal source of S. Enteritidis in Denmark. This conclusion was reached through the use of an exposure time window that corresponds to the most relevant incubation period rather than the maximum incubation period. The authors recommend this method in studies that have the objective of determining risk associated with common exposures. (+info)
Suppressors of the egg-laying defective phenotype of sel-12 presenilin mutants implicate the CoREST corepressor complex in LIN-12/Notch signaling in C. elegans.
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Presenilin is an essential component of the LIN-12/Notch signaling pathway and also plays a critical role in the genesis of Alzheimer's disease. Previously, a screen for suppressors of the egg-laying defective phenotype caused by partial loss of presenilin activity in Caenorhabditis elegans identified a number of new spr genes that are potentially involved in the regulation of LIN-12/Notch signaling or presenilin activity. Here we report the molecular identity of two spr genes, spr-1 and spr-5. Our genetic analysis indicates that loss of spr-1 elevates lin-12/Notch gene activity in many different cell fate decisions, suggesting that spr-1 is a negative regulator of LIN-12/Notch signaling. Sequence analysis revealed that spr-1 is an ortholog of human CoREST, a known corepressor. SPR-1 is localized to the nucleus and acts in a cell-autonomous manner; furthermore, human CoREST can substitute for SPR-1 in C. elegans. We also show that spr-5 encodes a homolog of p110b, another known member of the CoREST corepressor complex. Our results suggest that the CoREST corepressor complex might be functionally conserved in worms, and we discuss the potential role of SPR-1 and SPR-5 in the repression of transcription of genes involved in, or downstream of, LIN-12/Notch signal transduction. (+info)
Risk factors for salmonella food poisoning in the domestic kitchen--a case control study.
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Domestic kitchen food handling risk factors for sporadic salmonella food poisoning are largely unknown. We compared food consumption and food handling practices, opportunities for cross contamination and refrigerator temperature control, in 99 households in South East Wales in 1997/8 with a case of salmonella food poisoning, and control households matched for electoral ward. On univariate analyses, cases were significantly more likely than control respondents to have purchased free-range eggs in the preceding week, and more likely than control households to have handled frozen whole chicken in the previous week, and to handle raw chicken portions at least weekly. In multivariate analysis, only consumption of raw eggs and handling free-range eggs were significant risk factors, independent of the age structure of the family and of the season. (+info)