Escherichia coli heat-stable enterotoxin b (STb) in vivo internalization within rat intestinal epithelial cells     

Labrie V  Harel J  Dubreuil JD 《Veterinary research》2002,33(2):223-228

Heat-stable enterotoxin b (STb) is a low molecular weight toxin known to bind sulfatide, its receptor. The fate of STb bound to rat intestinal epithelium cells was followed using an anti-toxin gold labeled assay and transmission electron microscopy. The data suggest that STb toxin and the fusion protein maltose binding protein (MBP)-STb were internalized whereas its mutant I41 E-M42R with reduced hydrophobicity did not show internalization. There was a significant difference in the mean of gold particles per field between rat intestine incubated with STb or the fusion protein MBP-STb and the negative control consisting of intestine incubated with PBS alone. No subcellular compartment seems to be particularly aimed by the toxin as gold particles were randomly distributed within the cell.  相似文献   

Insecticidal activity of N-arylalkylbenzhydrolpiperidines     

Wierenga JM  Warkentin DL  Staetz CA  Pitts DL  Dybas JA 《Pest management science》2002,58(12):1266-1272

Benzhydrolpiperidine (BZP) insecticides represent a novel class of chemistry. Their specificity and efficacy as well as their low mammalian toxicity give them excellent potential for commercialization. Several N-arylalkylbenzhydrolpiperidines were tested for activity against a variety of insects in the laboratory and greenhouse. These tests were used to select compounds for field trials and determine rates of application for field tests. The BZP compounds have good activity against Lepidoptera, with modest Coleoptera activity. They are toxic by oral administration and have about 100-fold lower activity by topical exposure. A methyl carbamate BZP, F4265, was the most active compound, with LC50 values of 6 mg litre(-1) or less for most Lepidopteran species tested. F4265 was active in a variety of field trials at 112-224gAI ha(-1). Whole-plant testing methods conducted in the greenhouse were effective in determining field test rates.  相似文献   

VALIDATION OF DECONVOLUTIONAL ANALYSIS FOR THE MEASUREMENT OF HEPATIC FUNCTION IN DOGS WITH TOXIC-INDUCED LIVER DISEASE     

Gregory B.  Daniel  DVM  MS  Robert  Denovo  DVM  MS A. Eric  Schultze  DVM  PHD  Dorothy  Schmidt  BS  Gary T.  Smith  MD 《Veterinary radiology & ultrasound》1998,39(4):375-383

The extraction of the hepatobiliary radiopharmaceutical ^99mTc-mebrofenin ( Choletec ) by the liver can be used to evaluate the severity of hepatocellular disease. The hepatic parenchymal cells extract mebrofenin from the blood by the same active transport mechanism as bilirubin. The ability of the liver to extract ^99mTc-membrofenin is a measure of hepatic parenchymal cell function. In this study, we induced hepatocellular disease by administration of a hepatotoxic drug and compared a direct method of determining the hepatic extraction of ^99mTc-membrofenin to hepatic extraction fraction derived from deconvolutional analysis. We also compared both methods of calculating the hepatic extraction of ^99mTc-membrofenin to liver histopathology. Hepatic extraction fraction derived from deconvolutional analysis correlated very well to the direct measurement technique (R=0.922, p<0.001). Both methods of determining hepatic extraction correlated well to quantitative histopathology, having the same correlation coefficient and p values. (R=-0.833, p=0.003). As the hepatic extraction ^99mTc-membrofenin decreased, the severity of the histopathologic lesions of the liver increased in a linear fashion. There was a significant correlation of the hepatic excretion T_1/2 to quantititative histopathology (R=0.949, p<0.001). The hepatic excretion T_1/2 increased as the severity of the histopathologic lesions of the liver increased. Hepatic extraction (HEF) and excretion of ^99mTc-membrofenin are good predictors of the severity of hepatocellular damage in toxic induced liver disease. This study helps validate the premise that HEF derived from deconvolutional analysis ois a good predictor of the actual first pass hepatic extraction of ^99mTc-membrofenin.  相似文献   

Presumptive Baclofen Intoxication in a Dog     

Daniel V. Hecht VMD  MS  Karin Allenspach DMV 《Journal of Veterinary Emergency and Critical Care》1998,8(1):49-54

A five year old mixed breed dog weighing 30 kg., presumptively ingested six to twelve 20 mg baclofen tablets four to six hours prior to admission. The dog had been ataxic and vocalizing at home but was stuporous on presentation. Toxic effects noted were hypothermia, hypertension and sedation, followed by prolonged agitation. Treatment consisted of administration of activated charcoal, fluid diuresis, sodium nitroprusside, and diazepam. Baclofen overdose has been reported frequently in humans, but this is the first report of it in a dog. (Vet Emerg & Crit Care, 1998; 8: 49–54)  相似文献   

Bone Strength and Acetylcholinesterase Inhibition as Endpoints in Chlorpyrifos Toxicity toFundulus heteroclitus     

Daniel J. Karen  Robert Draughn  Michael Fulton  Philippe Ross 《Pesticide biochemistry and physiology》1998,60(3):167

Brain acetylcholinesterase (AChE) inhibition was measured during 4-week and 4-day episodic exposures to chlorpyrifos. Organisms were exposed to a seawater (−) control, an acetone (+) control (0.1%), and 0.625, 1.25, 2.5, 5.0, and 10.0 μg of chlorpyrifos L⁻¹in each test. These episodic exposures significantly depressed AChE activity at 2.5, 5.0, and 10.0 μg L⁻¹(weekly test) and at 1.25, 2.5, 5.0, and 10.0 μg L⁻¹(daily test). Six-hour pulsed exposure to chlorpyrifos inhibited brain AChE activity at concentrations as low as 1. 25 μg L⁻¹. Stress at failure of caudal vertebrae following episodic exposure was also tested. Analysis of samples from daily 6-h treatments found no differences after 2 days; however, vertebrae were significantly weaker (than controls) after 4 days. Analysis of weekly 6-h exposures found weaker caudal vertebrae after 2 weeks but not after 4 weeks.  相似文献   

Some features of the ecology of fleas inhabiting the nests of the suslik (Citellus citellus (L.)). I: Population dynamics, sex ratio, feeding, reproduction     

J Ryba  P R?dl  L Bartos  M Daniel  V Cerny 《Folia parasitologica》1986,33(3):265-275

While studying the suslik fleas in artificial nests planted in free nature, significant changes in the population dynamics of N. setosa, C. simplex and C. orientalis (from the spring build up to the autumnal peak and the decrease of flea number until the next spring) were noted. The predominance of females in the spring period was recorded in N. setosa. Significant seasonal changes in the number of engorged females of N. setosa and C. simplex and of C. orientalis males (the increase of engorged specimens in the spring and summer) were demonstrated. A significant predominance of females with mature eggs in the spring and summer and their negligible number in the autumn were found in N. setosa and C. simplex.  相似文献   

Capillariids (Nematoda: Capillariidae) from passeriform birds of Nepal).     

V Barus  M Daniel 《Folia parasitologica》1976,23(2):105-110

A total of 83 hosts of the order Passeriformes from Nepal were examined for nematodes. Nine of them were found to be infected with 4 nematode species, Capillaria exilis, C. ovopunctata, Capillaria sp. and Thominx rigidula. The last species is redescribed in detail. Three of the definitive hosts are new for the above-mentioned nematode species and this is the first recorded from Nepal.  相似文献   

N-acetyl- beta -D-glucosaminidase activity in the endometrial epithelium of the cow's uterus during the oestrous cycle and pregnancy     

Hussain AM  Daniel RC  O'Boyle D  Frost AJ 《New Zealand veterinary journal》1992,40(1):4-7

The levels of N-acetyl-beta-D-glucosaminidase (NAGase) were measured in the endometrial epithelial tissue of the bovine uterus during the oestrous cycle and during pregnancy. NAGase levels were significantly (P<0.001) higher in the epithelial tissue of the cow's uterus during the luteal phase of the cycle and during pregnancy than during the non-luteal phase. There were significantly (P<0.001) higher mean NAGase values in the epithelial than the subepithelial layers of the uterus in the two cycle phases and in pregnancy. Leucocyte numbers were significantly (P<0.05 and P<0.001) higher in the cows' uteri during the non-luteal phase than during the luteal phase and pregnancy, respectively. It is concluded that the endometrial epithelial layer is significantly active in terms of NAGase release and that this may be related to increased progesterone concentrations. In addition, the epithelial tissue (not leucocytes) appears to be the main contributor to the total NAGase activity in uterine tissue.  相似文献   

Land use and forest cover on private parcels in the Upper Midwest USA, 1970 to 1990     

Brown  Daniel G. 《Landscape Ecology》2003,18(8):777-790

This paper analyzes the interactions between land use and forest cover in the Upper Midwest, USA from 1970 to 1990. New data are presented and interpreted to evaluate the effects of land-use changes, especially abandonment of agriculture and dispersed development, on forest cover throughout the region. Forest-cover data were collected from Landsat satellite imagery and land use was interpreted from aerial photographs for land parcels, based on archival maps of land ownership. In general, forest cover increased throughout the region and throughout the period. Simultaneously, the area used for agriculture declined, much of it being converted to natural uses, and the area of land in low density residential development increased. Forest cover increased most rapidly on low density residential lands and in counties in which a large percentage of homes were for seasonal use (i.e., vacation homes). The data suggest that the transformation of the region from an extractive (i.e., forestry and agriculture) to a recreation-based service economy has played a significant role in the increasing forest cover observed throughout the region. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Analyzing a forest conversion history database to explore the spatial and temporal characteristics of land cover change in Guatemala's Maya Biosphere Reserve   总被引：3，自引：0，他引：3  

Hayes  Daniel J.  Sader  Steven A.  Schwartz  Norman B. 《Landscape Ecology》2002,17(4):299-314

We analyzed forest clearing and regrowth over a 23-year time period for 21 forest concession and management units within the Maya Biosphere Reserve(MBR), Guatemala. The study area as a whole experienced a clearing rate of0.16%/year from 1974 through 1997. The overall clearing rate appears rather low when averaged over the entire study area over 23 years because most of the reserve was inaccessible. However, despite the granting of legal protection to the MBR in 1990, clearing rates continued to rise, with the highest rates occurring in the most recent time period in the analysis, 1995 to1997. Higher rates of clearing relative to regrowth occurred in newly established communities and in the Reserve's buffer zone, where the clearing of high forest was preferred for pasture development. Exploratory models were built and analyzed to examine the effects of various landscape variables on forest clearing. The different units in the analysis showed different relationships of forest clearing with variables such as forest cover type and distance to access(roads and river corridors). Where available, socio-economic household survey data helped to explain patterns and trends observed in the time series Landsat imagery. A strong relationship between forest clearing and distance to access was demonstrated. More clearing occurred further from roads during later time periods as farmers moved deeper into the forest to find land to clear. Communities inside the MBR that were less dependent on farming had forest clearing to regrowth ratios of one:one or less. These communities used fallow fields in greater proportions than communities in the Reserve's buffer zone. General trends in clearing by forest cover type suggest a preference for clearing high forest (bosque alto) types found on the higher elevation, better-drained soils, and fallow fields,and an avoidance of low-lying, seasonally flooded terrain(bajos). Satellite remote sensing observations of forest clearing and regrowth patterns can provide an objective source of information to complement socio-economic studies of the human driving forces in land cover and land use change. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献