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1.
Schuler D Chevalier HJ Merker M Morgenthal K Ravanat JL Sagelsdorff P Walter M Weber K McGregor D 《Journal of toxicologic pathology》2011,24(3):149-162
Inhalation of vanadium pentoxide clearly increases the incidence of
alveolar/bronchiolar neoplasms in male and female B6C3F1 mice at all
concentrations tested (1, 2 or 4 mg/m3), whereas responses in F344/N
rats was, at most, ambiguous. While vanadium pentoxide is mutagenic in
vitro and possibly in vivo in mice, this does not
explain the species or site specificity of the neoplastic response. A nose-only
inhalation study was conducted in female B6C3F1 mice (0, 0.25, 1 and
4 mg/m3, 6 h/day for 16 days) to explore histopathological,
biochemical (α-tocopherol, glutathione and F2-isoprostane) and genetic (comet
assays and 9 specific DNA-oxo-adducts) changes in the lungs. No treatment
related histopathology was observed at 0.25 mg/m3. At 1 and
4 mg/m3, exposure-dependent increases were observed in lung
weight, alveolar histiocytosis, sub-acute alveolitis and/or granulocytic
infiltration and a generally time-dependent increased cell proliferation rate of
histiocytes. Glutathione was slightly increased, whereas there were no
consistent changes in α-tocopherol or 8-isoprostane F2α. There was no evidence
for DNA strand breakage in lung or BAL cells, but there was an increase in
8-oxodGuo DNA lesions that could have been due to vanadium pentoxide induction
of the lesions or inhibition of repair of spontaneous lesions. Thus, earlier
reports of histopathological changes in the lungs after inhalation of vanadium
pentoxide were confirmed, but no evidence has yet emerged for a genotoxic mode
of action. Evidence is weak for oxidative stress playing any role in lung
carcinogenesis at the lowest effective concentrations of vanadium pentoxide. 相似文献
2.
3.
Sixteen Friesland heifer calves aged between 96 and 157 days were removed from a dairy farm that had been polluted with vanadium
and randomly allocated into two equal groups (n = 8). The objective of the trial was to determine whether calcium disodium
ethylenediaminetetraacetate (CaNa2EDTA) could be used as a treatment for cattle running in environments high in background vanadium. The treatment group received
80 mg CaNa2EDTA per kg body weight intraperitonealy (i.p.) twice a week over a 10-week period. The control group received normal saline
i.p. over the same period. During the trial calves were exposed to a daily intake of vanadium in the form of contaminated
tef hay derived from the farm of origin. In addition, the total mixed ration was spiked with a further 20 mg V2O5/kg feed to compensate for possible on-farm inhalation exposure. A stochastic model was used to estimate daily intake of vanadium
as a distribution function. The model estimated that the daily intake of vanadium varied between an absolute minimum of 33
mg/day to an absolute maximum of 124 mg/day. The average intake of vanadium was 71.8 mg per day per calf. Various chemical
pathology parameters were measured throughout the trial as well as urine excretion rates of vanadium and lymphocyte stimulation
counts. All calves were slaughtered and necropsied in cohorts of 4–6 animals at monthly intervals after completion of the
trial and withdrawal of vanadium from the ration. Tissue concentrations of vanadium were determined and necropsy findings
were noted. The study found that CaNa2EDTA appears to enhance the excretion of vanadium in calves, but could not prove that the treatment had a protective effect
against vanadium exposure. Calves were able to tolerate the prolonged treatment with CaNa2EDTA without side-effects. 相似文献
4.
Bernardo Baldisserotto Thaylise V. Parodi E Don Stevens 《Veterinary anaesthesia and analgesia》2018,45(1):48-56
Objective
To test the postexposure analgesic efficacy of low doses of eugenol in zebrafish.Study design
Prospective experimental study.Animals
A total of 76 large adult zebrafish (Danio rerio).Methods
Fish swimming behavior (median velocity, freeze time, high-speed swimming and distance moved in the vertical direction) was recorded in a 1.6 L video arena before and after exposure to eugenol (0, 1, 2, 5, 10 and 20 mg L?1). In a second experiment, fish were anesthetized with 2-phenoxy-ethanol and treated with an injection of 5% acetic acid (noxious stimulus), and then exposed to 0, 1, 2 and 5 mg L?1 eugenol. The fish swimming behavior was also recorded.Results
The higher doses (10 and 20 mg L?1) reduced the median velocity, high-speed swimming and distance moved in the vertical direction, and increased the freeze time. Zebrafish behavior was not altered by eugenol (1, 2 and 5 mg L?1) after noxious stimulation.Conclusions and clinical relevance
The change in the behavior of zebrafish associated with a noxious stimulus can be monitored and is a good model for studying analgesia in fish. Eugenol (10 and 20 mg L?1) induced zebrafish sedation. The response after a noxious stimulus was not affected by postexposure to lower doses, and thus we cannot recommend its use as an analgesic. 相似文献5.
Felix Garlipp MSc Engel F. Hessel Matthieu van den HurkMark F. Timmerman Dr. Herman F.A. Van den Weghe 《Journal of Equine Veterinary Science》2010
Four different types of bedding materials (wheat straw, wood shavings, hemp shives, flax shives) and two roughages (hay, haylage) were treated using an air-driven particle separation technology. The airborne particle and mold generation of both treated and untreated samples were then analyzed under standardized laboratory conditions. In addition, samples of all the treated materials were stored for 8 weeks either in a pressed or incoherent form and then analyzed again for their ability to generate airborne particles. The airborne particle concentrations were detected online with the gravimetrically measuring analyzer tapered element oscillating microbalance (TEOM) 1400a that was equipped successively with different inlets to measure the particle fractions PM20, PM10, PM2.5, and PM1.0 (PM = Particulate matter). The particle separation resulted in a reduction in the airborne particle (PM20) generation in all materials: hay 49.16 to 22.79 mg/m3 (53.6%), haylage 28.57 to 25.04 mg/m3 (12.3%), wood shavings 141.68 to 15.04 mg/m3 (89.4%), wheat straw 143.08 to 22.97 mg/m3 (83.9%), flax 135.11 to 53.31 mg/m3 (60.5%), and hemp 63.67 to 17.64 mg/m3 (72.3%). The 8-week storage of the treated materials as compressed materials led to a renewed significant increase in the airborne particle (PM10) concentration in the haylage (+29.9%), wheat straw (+104.0%), wood shavings (+40.4%), and hemp shives (+30.7%). Storage of the incoherent materials caused a significant increase in these particles only in the wheat straw (+44.2%). The separation treatment reduced the mold production by 92.4% in the wood shavings, 88.0% in the wheat straw, and 85.8% in the hay. 相似文献
6.
《Journal of aquatic animal health》2013,25(4):330-339
Abstract Laboratory exposures to the infectious stages (triactinomyxons) of Myxobolus cerebralis demonstrated a range of susceptibility to whirling disease among four species of inland salmonids. Replicate groups of each species were exposed to two concentrations of triactinomyxons, a low dose (100–200 per fish) and a high dose (1,000–2,000 per fish). Exposed fish were evaluated for clinical signs, for severity of microscopic lesions at 35 d, 2 and 5 months, and for spore concentrations in the head cartilage at 5 months. A standard strain of rainbow trout Oncorhynchus mykiss matched for age served as a susceptible species control. Rainbow trout, westslope cutthroat trout O. clarki lewisi, Yellowstone cutthroat trout O. clarki bouvieri, and bull trout Salvelinus confluentus were susceptible to M. cerebralis infections. Clinical signs, including radical swimming (“whirling”) and black tails, were observed at 7 weeks postexposure among rainbow and cutthroat trout challenged at 3 weeks of age. Clinical signs were rare among bull trout exposed at an age of 4 weeks and absent among rainbow and cutthroat trout exposed at 3 months posthatch. Most rainbow, cutthroat, and bull trout were found to be infected when examined at 5 months postexposure. The most severe microscopic lesions among infected fish at 5 months postexposure were found among rainbow trout. Cutthroat trout had less severe lesions, bull trout had mild infections, and no evidence of infection was found among Arctic grayling Thymallus arcticus. Mean spore concentrations among infected fish correlated with the severity of microscopic lesion scores. Rainbow trout had mean concentrations of spores in head cartilage reaching 106, whereas more resistant species such as bull trout had 104 spores; no spores were found among Arctic grayling at 5 months postexposure. 相似文献
7.
Takamasa Numano Taiki Sugiyama Mayumi Kawabe Yukinori Mera Ryoji Ogawa Ayako Nishioka Hiroko Fukui Kei Sato Yuji Hagiwara 《Journal of toxicologic pathology》2021,34(1):57
Carbon fibers have excellent physicochemical and electrical properties. Vapor-grown carbon fibers are a type of carbon fibers that have a multi-walled carbon tube structure with a high aspect ratio. The representative vapor-grown carbon fiber, VGCFTM-H, is extremely strong and stable and has superior thermal and electrical conductivity. Because some high-aspect-ratio multi-walled carbon nanotubes (MWCNTs) have been reported to have toxic and carcinogenic effects in the lungs of rodents, we performed a 13-week lung toxicity study using VGCFTM-H in comparison with one of MWCNTs, MWNT-7, in rats. Male and female F344 rats were intratracheally administered VGCFTM-H at doses of 0.2, 0.4, and 0.8 mg/kg bw or MWNT-7 at doses of 0.4 and 0.8 mg/kg bw once a week for 8 weeks and then up to week 13 without treatment. The lung burden was equivalent in the VGCFTM-H and MWNT-7 groups; however, the lung weight had increased and the inflammatory and biochemical parameters in the broncho-alveolar lavage fluid and histopathological parameters, including inflammatory cell infiltration, alveolar type II cells proliferation, alveolar fibrosis, pleural fibrosis, lung mesothelium proliferation, and diaphragm fibrosis, were milder in the VGCFTM-H group than in the MWNT-7 group. In addition, the proliferating cell nuclear antigen (PCNA)-positive index in the visceral and pleural mesothelium was significantly higher in the MWNT-7 group than in the controls, but not in the VGCFTM-H group. Thus, the results of this study indicate that the lung and pleural toxicities of VGCFTM-H were less than those of MWNT-7. 相似文献
8.
Schooley EK McGee Turner JB Jiji RD Spinka CM Reinero CR 《American journal of veterinary research》2007,68(11):1265-1271
OBJECTIVE: To determine whether oral administration of cyproheptadine or cetirizine blocks the action of serotonin and histamine, respectively, and results in diminished eosinophilic airway inflammation in cats with experimentally induced asthma. ANIMALS: 9 cats in which asthma was experimentally induced through exposure to Bermuda grass allergen (BGA) during a 3-month period. PROCEDURES: Cats were randomized to receive monotherapy with each of 3 treatments for 1 week: placebo (flour in a gelatin capsule, PO, q 12 h), cyproheptadine (8 mg, PO, q 12 h), or cetirizine (5 mg, PO, q 12 h). A 1-week washout period was allowed to elapse between treatments. Prior to and following each 1-week treatment period, blood and bronchoalveolar lavage fluid (BALF) samples were collected. The percentage of eosinophils in BALF was evaluated to determine treatment efficacy. Serum and BALF BGA-specific immunoglobulin contents and plasma and BALF histamine concentrations were determined via ELISAs. Plasma and BALF serotonin concentrations were measured by use of a fluorometric method. RESULTS: The mean +/- SD percentage of eosinophils in BALF did not differ significantly among treatment groups (placebo, 40 +/- 22%; cyproheptadine, 27 +/- 16%; and cetirizine, 31 +/- 20%). Among the treatment groups, BGA-specific immunoglobulin content and histamine and serotonin concentrations were not significantly different. CONCLUSIONS AND CLINICAL RELEVANCE: In cats with experimentally induced asthma, cyproheptadine and cetirizine were not effective in decreasing airway eosinophilic inflammation or in altering several other measured immunologic variables. Neither cyproheptadine nor cetirizine can be advocated as monotherapy for cats with allergen-induced asthma. 相似文献
9.
Charleata A. Carter Manoj Misra Robert R. Maronpot 《Journal of toxicologic pathology》2012,25(3):201-207
A short-term 5-day nose-only cigarette smoke exposure study was conducted in Fisher 344
rats to identify smoke-induced tracheal protein changes. Groups of 10 male and female 5
week old rats were assigned to 1 of 4 exposure groups. Animals received filtered air, or
75, 200 or 400 mg total particulate matter (TPM)/m3 of diluted 3R4F Kentucky
reference cigarette mainstream smoke. Exposures were conducted for 3 hrs/day, for 5
consecutive days. Tracheas from half the rats were processed for pathology, and tracheas
from the other half of the rats frozen immediately for proteomics. We hypothesized that
smoke will activate tracheal inflammatory, apoptotic, proliferative, and stress-induced
pathways. Mucosal epithelial toxicity from the inhaled material was evidenced by cilia
shortening and loss of tracheal mucosal epithelium in smoke-exposed animals. Mucosal
thinning occurred in all smoke-exposed groups with hyperplastic reparative responses in
the 200 and 400 mg TPM/m3 groups. Tracheal lysates from control vs. treated
animals were screened for 800 proteins using antibody-based microarray technology and
subsequently the most changed proteins evaluated by Western blot. Tracheal proteins
expressed at high levels that were markedly increased or decreased by smoke exposure
depended on dose and gender and included caspase 5, ERK 1/2 and p38. Signaling pathways
common between the morphologic and protein changes were stress, apoptosis, cell cycle
control, cell proliferation and survival. Changes in identified proteins affected by smoke
exposure were associated with tracheal mucosal pathology, may induce functional tracheal
changes, and could serve as early indicators of tracheal damage and associated
disease. 相似文献
10.
P. K. Hershberger J. L. Gregg C. A. Grady S. E. LaPatra J. R. Winton 《Journal of aquatic animal health》2013,25(3):140-147
Abstract The plasma of Pacific herring Clupea pallasii that survived laboratory-induced viral hemorrhagic septicemia (VHS) epizootics contained humoral substances that, when injected into naïve animals, conferred passive immunity against the disease. Among groups exposed to viral hemorrhagic septicemia virus (VHSV), injection of donor plasma from VHS survivors resulted in significantly greater survival (50%) and significantly lower tissue titers (1.5 × 105 plaque-forming units [PFU]/g) than the injection of plasma from VHSV-naïve donors (6% survival; 3.7 × 106 PFU/g). Additionally, the magnitude of the protective immune response increased during the postexposure period; plasma that was collected from survivors at 123 d postexposure (931 degree-days) provided greater protection than plasma collected from survivors at 60 d postexposure (409 degree-days). These results provide proof of concept that the VHSV exposure history of Pacific herring populations can be determined post hoc; furthermore, the results can be used as the foundation for developing additional high-throughput diagnostic techniques that may be effective at quantifying herd immunity and forecasting the potential for future VHS epizootics in populations of wild Pacific herring. Received October 20, 2010; accepted April 7, 2011 相似文献
11.
Felix Garlipp Engel F. HesselHerman F.A. van den Weghe Prof Dr Ir 《Journal of Equine Veterinary Science》2011,31(7):383-395
The aim of this study was to analyze the influence of horse manure added to different bedding materials on the generation of gases (ammonia (NH3), nitrous oxide, carbon dioxide, methane, water vapor) from deep litter bedding under standardized laboratory conditions. Two different types of straw (wheat and rye) and wood shavings were analyzed. The deep litter (substrate) was made of 25 kg of the respective bedding material, 60 kg horse feces, and 60 L ammonium chloride solution (urea), and spread out in identical chambers over 19 days (n = 3). On days 1, 8, 15, and 19, total nitrogen, total carbon, and dry matter content of the substrate, as well as the pH in 500-g samples, were measured along with. At the end of each test period, the nitrite nitrogen, nitrate nitrogen, and ammonium nitrogen contents of the leachate were analyzed. The wheat straw substrate emitted the highest concentration of NH3 (4.31 mg/m3; P < .0001) and the wood shavings substrate emitted the lowest (1.73 mg/m3; P < .0001); the rye straw substrate generated 3.05 mg/m3. In addition, significant differences occurred during days 1 to 3 with respect to the generation of the gases NH3, methane, nitrous oxide, carbon dioxide, and water vapor, and after the opening of the chamber on day 15. The nitrogen losses through the leachate occurred mainly in the form of nitrate, where the leachate from the wheat straw substrate had a significantly higher amount of nitrate nitrogen (44.56 mg) as compared with the leachates of the rye straw (14.49 mg; P ≤ .0001) and the wood shaving substrates (22.62 mg; P = .0010). 相似文献
12.
Mohammed Ahmed UMAR Sho FUKUI Kodai KAWASE Takaharu ITAMI Kazuto YAMASHITA 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2015,77(3):281-288
Cardiovascular effects of total intravenous anesthesia using
ketamine-medetomidine-propofol drug combination (KMP-TIVA) were determined in 5
Thoroughbred horses undergoing surgery. The horses were anesthetized with intravenous
administration (IV) of ketamine (2.5 mg/kg) and midazolam (0.04 mg/kg) following
premedication with medetomidne (5 µg/kg, IV) and artificially ventilated.
Surgical anesthesia was maintained by controlling propofol infusion rate (initially 0.20
mg/kg/min following an IV loading dose of 0.5
mg/kg) and constant rate infusions of ketamine (1 mg/kg/hr) and medetomidine
(1.25 µg/kg/hr). The horses were anesthetized for 175 ± 14 min (range
from 160 to 197 min). Propofol infusion rates ranged from 0.13 to 0.17 mg/kg/min, and
plasma concentration (Cpl) of propofol ranged from 11.4 to 13.3
µg/ml during surgery. Cardiovascular measurements
during surgery remained within clinically acceptable ranges in the horses (heart rate: 33
to 37 beats/min, mean arterial blood pressure: 111 to 119 mmHg, cardiac index: 48 to 53
ml/kg/min, stroke volume: 650 to 800 ml/beat and
systemic vascular resistance: 311 to 398 dynes/sec/cm5). The propofol Cpl
declined rapidly after the cessation of propofol infusion and was significantly lower at
10 min (4.5 ± 1.5 µg/ml), extubation (4.0 ± 1.2
µg/ml) and standing (2.4 ± 0.9
µg/ml) compared with the Cpl
at the end of propofol administration (11.4 ± 2.7
µg/ml). All the horses recovered uneventfully and stood
at 74 ± 28 min after the cessation of anesthesia. KMP-TIVA provided satisfactory quality
and control of anesthesia with minimum cardiovascular depression in horses undergoing
surgery. 相似文献
13.
《Journal of aquatic animal health》2013,25(2):122-125
Abstract After parenteral treatment with the cyclooxygenase inhibitor indomethacin, channel catfish Ictalurus punctatus were exposed to mature spores of an Aurantiactinomyxon sp. demonstrated to be the etiological agent of proliferative gill disease (PGD). Fish that received indomethacin at a dose of 2.0 or 5.0 mg/kg body weight within 0.5 h before exposure to the myxozoan and again at 24 h postexposure had significantly (P < 0.05) less severe gill lesions 7 d after exposure than fish that received the drug vehicle alone. Fish that received 0.5 mg indomethacin/kg had moderately severe lesions. All fish were confirmed to be infected with the organism associated with PGD by microscopic examination of gills 4 or 7 d postexposure. These results suggest that products of the cyclooxygenase pathway (e.g., prostaglandins) participate in the pathophysiologic host response to PGD. 相似文献
14.
Yoshikawa T Moriyama A Kodama R Sasaki Y Sunagawa T Okazaki T Urashima A Nishida Y Arima A Inoue A Negishi T Yoshikawa Y Ihara T Maeda H 《Journal of toxicologic pathology》2011,24(4):215-222
To evaluate morphologic alterations in the thyroid gland in the second generation in cynomolgus monkeys, pregnant dams were exposed to high doses of thiamazole. In Experiment A, dams received thiamazole intragastrically via a nasogastric catheter from gestation day (GD) 50 to GD 150 or on the day before delivery. Initially, the dose level was 20 mg/kg/day (10 mg/kg twice daily); however, the dose level was subsequently decreased to 5 mg/kg/day (2.5 mg/kg twice daily), since deteriorated general conditions were observed in two dams. Six out of seven neonates died on the day of birth. The cause of neonatal death was tracheal compression and suffocation from goiter. The transplacental exposure to thiamazole affected the fetal thyroid glands and induced goiter in all neonates. The surviving neonate was necropsied 767 days after discontinuation of thiamazole exposure and showed reversibility of the induced changes. In Experiment B, dams were intragastrically administered thiamazole at 5 mg/kg/day (2.5 mg/kg twice daily) for treatment periods from GDs 51 to 70, 71 to 90, 91 to 110, 111 to 130 and 131 to 150. All fetuses showed enlarged thyroid glands but were viable. Histopathologically, hypertrophy and/or hyperplastic appearance of the follicular epithelium of the thyroid gland was observed at the end of each treatment period. The most active appearance of the follicular epithelium, consisting of crowded pedunculated structure, was demonstrated at end of the treatment period from GD 131 to 150. This is the first report on the morphology of fetal and neonatal goiter in the cynomolgus monkey. 相似文献
15.
An Open‐label Phase 1 Dose‐escalation Clinical Trial of a Single Intravenous Administration of Gemcitabine in Dogs with Advanced Solid Tumors 下载免费PDF全文
L. Marconato R. Finotello U. Bonfanti M. Dacasto L. Beatrice S. Pizzoni V.F. Leone G. Balestra T. Furlanello C. Rohrer Bley L. Aresu 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2015,29(2):620-625
Background
A broad range of gemcitabine dosages have been used in dogs.Hypothesis/Objectives
To determine maximally tolerated dose (MTD), dose‐limiting toxicity (DLT), and preliminary antitumor activity of intravenous administration of gemcitabine in dogs with advanced solid tumors.Animals
Twenty‐two client‐owned dogs.Methods
Dogs with advanced cancer were prospectively enrolled in an open‐label Phase 1 study of gemcitabine. Gemcitabine was administered as a 30‐minute intravenous bolus starting at 800 mg/m2, using escalation of 50 mg/m2 increments with 3 dogs per dose level. MTD was established based on the number of dogs experiencing DLT assessed after 1 cycle. Treatment continued until disease progression or unacceptable toxicosis. Additional dogs were enrolled at MTD to better characterize tolerability, and to assess the extent and duration of gemcitabine excretion.Results
Twenty‐two dogs were treated at 4 dose levels, ranging from 800 to 950 mg/m2. Neutropenia was identified as DLT. MTD was 900 mg/m2. DLT consisting of grade 4 febrile neutropenia was observed at 950 mg/m2 in 2 dogs. There were no nonhematologic DLTs. Twenty dogs received multiple doses, and none had evidence of severe toxicosis from any of their subsequent treatments. At 900 mg/m2, 2 complete and 5 partial responses were observed in dogs with measurable tumors. The amount of gemcitabine excreted in urine decreased over time, and was undetectable after the first 24 hours.Conclusions and Clinical Importance
The recommended dose of gemcitabine for future Phase 2 studies is weekly 900 mg/m2. In chemotherapy‐naïve dogs with advanced solid tumor this dose level merits further evaluation. 相似文献16.
D.B. Bailey K.M. Rassnick O. Kristal J.D. Chretin C.E. Balkman 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2008,22(6):1397-1402
Background: Vinblastine (VBL) is commonly used in dogs at a dosage of 2.0 mg/m2. The minimal toxicity observed at this dosage indicates that higher dosages might be well tolerated. Hypothesis: The maximum tolerated dosage (MTD) for a single VBL treatment is higher than the previously published dosage of 2.0 mg/m2. Animals: Twenty‐three dogs with lymphoma or cutaneous mast cell tumors. Methods: Dogs received 1 single‐agent VBL treatment IV. The starting dosage was 3.0 mg/m2, and dosages were increased in increments of 0.5 mg/m2 in cohorts of 3 dogs. Hematologic toxicity was assessed with weekly CBCs. Gastrointestinal toxicity was assessed from medical histories from owners. Once the MTD was determined, additional dogs were treated with VBL at that dosage. Dogs whose cancers responded to VBL continued to receive treatments q2–3 weeks. Results: VBL dosages ranged from 3.0 to 4.0 mg/m2. Neutropenia was the dose‐limiting toxicity, with the nadir identified 7 days after treatment and resolving by 14 days after treatment. The MTD was 3.5 mg/m2. Sixteen dogs were treated at this dosage, and 3 experienced severe toxicity characterized by asymptomatic grade 4 neutropenia, febrile grade 4 neutropenia, and death. Gastrointestinal toxicity was mild and self‐limiting. Preliminary evidence of antitumor activity was identified in 2 of 12 dogs with lymphoma treated at the MTD. Conclusions and Clinical Importance: In dogs, single‐agent VBL is well tolerated at a dosage of 3.5 mg/m2 IV. At this dosage, the minimum safe treatment interval is q2 weeks, and adjunct treatment with prophylactic antibiotics should be considered. 相似文献
17.
Leukocyte levels were monitored weekly in chickens infected with the avian schistosome Austrobilharzia variglandis. Changes in relative and absolute numbers of leukocytes were recorded over a 7-week period beginning 1 week before exposure. There was a significant increase (P less than 0.001) in total leukocytes, peaking at 5.8 X 10(4) cells/mm3 on day 21 postexposure; controls had 2.4 X 10(4) cells/mm3 on that day. The leukocyte count declined over the next 3 weeks, returning to nearly normal levels by day 42 postexposure. With the exception of eosinophils, which peaked 35 days postexposure, all leukocyte subpopulations peaked in number on day 21. Increases in heterophils and monocytes were related to the schistosome egg burden. 相似文献
18.
Shafarin MS Zamri-Saad M Khairani BS Saharee AA 《Tropical animal health and production》2008,40(5):335-340
This report describes the proliferation and transmission patterns of Pasteurella multocida B:2 among stressful goats, created through dexamethasone injections. Thirty seven clinically healthy adult goats were divided
into three groups consisted of 15 goats in group A, 11 goats in group B and the remaining 11 in group C. At the start of the
study, all goats of group A were exposed intranasally to 1.97 × 1010 CFU/ml of live P. multocida B:2. Dexamethasone was immediately administered intramuscularly for 3 consecutive days at a dosage rate of 1 mg/kg. The exposed
goats were observed for signs of HS for a period of 1 month. At the end of the 1-month period, 11 goats from group B were
introduced into and commingled with the surviving goats of group A before all goats from both groups were immediately injected
intramuscularly with dexamethasone for 3 consecutive days. The treatment with dexamethasone was then carried out at monthly
interval throughout the 3-month study period. Goats of group C were kept separately as negative control. Three surviving goats
from each group were killed at 2-week interval for a complete post-mortem examination. Two (13%) goats of group A were killed
within 24 hours after intranasal exposure to P. multocida B:2 while another two (13%) goats from the same group were killed on day 40, approximately 10 days after the second dexamethasone
injection. All four goats showed signs and lesions typical of haemorrhagic septicaemia. Bacteraemia was detected in 3 goats
of group A that were having rectal temperature higher than 41°C. The P. multocida B:2 isolation pattern was closely associated with dexamethasone injections when significantly (p < 0.05) higher rate of isolations
from both groups were observed after each dexamethasone injection. Transmission of P. multocida B:2 from goats of group A to group B was successful when P. multocida B:2 was isolated from goats of group B for a period of 28 days. There was a strong correlation between dexamethasone injections,
rate of bacterial isolation and serum cortisol level. The IgG level showed an increasing trend 2 weeks after exposure to P. multocida B:2 and remained high throughout the study period. 相似文献
19.
《Journal of aquatic animal health》2013,25(3):152-160
Abstract A series of experiments was carried out with infectious hematopoietic necrosis virus (IHNV; 193-110 isolate) in rainbow trout Oncorhynchus mykiss (weight, ~1.2 g) to determine the duration of the patent period and the timing of onset of the infectious periods. We first attempted to transmit IHNV to recipient fish from infected rainbow trout 2–3 d after they had been exposed. No infection transfer occurred despite high titers (104.79 to 104.91 plaque-forming units 5–8 d postexposure (dpe). To determine the number of secondary cases produced by one infectious individual, we exposed approximately 50 rainbow trout (weight, ~1.5 g) in each of seven replicate tanks to a donor fish that had been infected with virus by bath exposure 3 d earlier. The prevalence of infection in recipient fish rose from 0.84% at 2 dpe to 7.9% at 6 dpe. Maximum incidence (22 cases) occurred between 2 and 4 dpe. No disease-specific mortalities occurred in recipient fish during the experiment. The titer of virus in both recipient and donor fish increased from 2 to 4 dpe. There was a positive correlation between the level of infection among donors and prevalence values among recipient fish (r 2 = 0.60). The level of challenge by one infectious fish under the conditions provided was enough for infection transfer from sick cohabitant to susceptible fish but was not enough for initiation of a full-scale epizootic among recipients. 相似文献
20.
Thania R. R. Lima Nathlia P. Souza Ana P. Ferragut Cardoso Lígia M. M. Gomide Merielen G. Nascimento e Pontes Hlio A. Miot Lora L. Arnold Samuel M. Cohen Joo Lauro V. de Camargo 《Journal of toxicologic pathology》2022,35(2):159
Exposure of Sprague-Dawley (SD) rats to acrylamide (AA) or di-butyl-phthalate (DBP) from the 12th gestational day to the 16th postnatal week (PNW) has been shown to reduce the effectiveness of orchiopexy in recovering the testicular alterations associated with experimental cryptorchidism established at weaning. Herein, we provide information about the long-term effects of AA or DBP on the testes of cryptorchid/orchiopexic rats. Male offspring exposed in utero to 10 mg/kg/day AA or 500 mg/kg/day DBP underwent bilateral surgical cryptorchidism at the 3rd PNW and orchiopexy at the 6th week, with continuous exposure to the chemicals through diet until the 58th week. Regardless of the test chemical, there were severe qualitative/quantitative alterations in the seminiferous tubules and increased numbers of Leydig cells. There was an increase and decrease in the number of tubules with c-Kit- and placental alkaline phosphatase-labeled germ cells, respectively, as compared to those in the control group, suggesting an imbalance between apoptosis and cell proliferation processes. The histological scores of the testicular lesions at the end of this one-year study were higher than those in the previous 16-week study, indicating that exposure of rats to the toxicants AA or DBP enhanced the testicular alterations induced by the chemicals beginning at the intra-uterine life, and impaired the effectiveness of orchiopexy in restoring the testes to normal morphology. Although the present experimental protocol does not completely replicate the natural human undescended testes, our findings may contribute to understanding the alterations occurring in cryptorchid/orchiopexic testes potentially exposed to exogenous chemicals for extended periods. 相似文献