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61.
Domestic cats are an important part of many Americans' lives, but effective control of the 60–100 million feral cats living throughout the country remains problematic. Although trap–neuter–vaccinate–return (TNVR) programmes are growing in popularity as alternatives to euthanizing feral cats, their ability to adequately address disease threats and population growth within managed cat colonies is dubious. Rabies transmission via feral cats is a particular concern as demonstrated by the significant proportion of rabies post‐exposure prophylaxis associated with exposures involving cats. Moreover, TNVR has not been shown to reliably reduce feral cat colony populations because of low implementation rates, inconsistent maintenance and immigration of unsterilized cats into colonies. For these reasons, TNVR programmes are not effective methods for reducing public health concerns or for controlling feral cat populations. Instead, responsible pet ownership, universal rabies vaccination of pets and removal of strays remain integral components to control rabies and other diseases.  相似文献   
62.
The branchial Ca2+ uptake by teleost fish is under inhibitory control by the hormone stanniocalcin (STC) which is generated by the corpuscles of Stannius (CS). Removal of the CS in North American eel, Anguilla rostrata LeSueur, induced a rapid rise in blood calcium levels. Branchial Ca2+ influx following the extirpation of the CS (stanniectomy, STX) increased during the first four days and stayed elevated thereafter (in agreement with previous studies). The transepithelial potential (TEP) across the gills did not change after STX and this means that the electrochemical gradient for Ca2+ is less favourable for passive influx of Ca2+ in STX eel. Therefore, the Ca2+ influx in STX eels is a transcellular flux, with Ca2+ crossing the apical and basolateral membrane barrier. The kinetics of ATP-driven Ca2+-transport across basolateral plasma membranes from eel gills did not change after STX. Thus, the increased Ca2+-influx after STX is not correlated with changes in ATP-dependent Ca2+-extrusion across the basolateral membrane, suggesting a regulation at the apical membrane. Moreover, STC did not affect ATP-driven Ca2+-transport in isolated basolateral membranes (in vitro). STC (0.1 nM) reduced cAMP levels in dispersed eel gill cells. It had no significant effect on the IP3 levels in these cells. We postulate that STC controls the permeability to Ca2+ of the apical membranes of the Ca2+ transporting cells of fish gills by controlling second messenger operated Ca2+ channels in the apical membrane.
Résumé L'entrée de calcium au niveau des branchies est sous le controle inhibiteur de la stanniocalcine (STC) qui est synthétisée au niveau des corpuscules de Stannius (CS). L'ablation des CS chez l'anguille d'Amérique du Nord, Anguilla rostrata LeSueur, induit une augmentation rapide des niveaux de calcium dans le sang. Le flux entrant branchial de calcium consécutif à l'ablation des CS (stanniectomie, STX) augmente pendant les 4 premiers jours et reste élevé au-delà (en accord avec des études antérieures). Le potentiel transépithélial (TEP) à travers les branchies ne change pas après STX, ceci indiquant que le gradient électrochimique du Ca2+ est moins favorable pour le flux entrant passif du Ca2+ chez l'anguille STX. En conséquence, le flux entrant de Ca2+ chez l'anguille STX est un flux transcellulaire, avec le Ca2+ traversant la barrière membranaire apicale et basolatérale. La cinétique du transport de Ca2+ conduit par l'ATP à travers les membranes plasmatiques basolatérales de branches d'anguille n'est pas modifiée après STX. Ainsi, l'augmentation du flux entrant de Ca2+ après STX n'est pas corrlée avec des modifications de l'excrétion de Ca2+ conduit par l'ATP à travers la membrane basolatérale, suggérant donc une régulation au niveau de la membrane apicale. De plus, la STC ne modifie pas le transport de Ca2+ conduit par l'ATP dans des membranes basolatérales isolées (in vitro). La STC (0.1 nM) réduit les niveaux d'AMPc dans des cellules dispersées de branchies d'anguille. Cette hormone n'a pas d'effet significatif sur les niveaux d'IP3 dans ces cellules. Nous suggérons que la STC régule la perméabilité au Ca2+ des membranes apicales des cellules branchiales transporteuses de Ca2+ en controlant un second messager agissant sur les canaux calciques de la membrane apicale.
  相似文献   
63.
The involvement of the freshwater fish gill chloride cells (CCs) in trans-branchial calcium uptake (JinCa2+) was investigated. This was accomplished by assessing the interspecific relationships between the apical surface area of CCs exposed to the external environment and JinCa2+. Three species of freshwater teleosts, the rainbow trout (Oncorhynchus mykiss), the American eel (Anguilla rostrata) and the brown bullhead catfish (Ictalurus nebulosus), were used. Chronic (ten-day) treatment with cortisol in each species was used as a tool to evoke variations in both JinCa2+ and gill CC morphology in order to assess intraspecific relationships between CC surface area and JinCa2+. The results of quantitative morphometry, based on analysis of scanning electron micrographs, demonstrated that catfish possessed the lowest fractional area of exposed CC (CCFA) on the gill filament epithelium (12,744 ± 2248 m2/mm2) and was followed, in increasing order, by American eel (21,355 ± 981 m2/mm2) and rainbow trout (149,928 ± 26,545 m2/mm2). With the exception of catfish, chronic treatment with cortisol caused significant increases in CCFA owing to proliferation of CCs and/or enlargement of individual CCs (eel only). The rates of JinCa2+ closely reflected the CC fractional area in each species. The results of correlation analysis revealed significant correlations between CC fractional area and JinCa2+ in trout and eel. Owing to the absence of an effect of cortisol treatment, there was no significant correlation in catfish because of insufficient variation in CC fractional area in this species. CC fractional area was significantly correlated with JinCa2+ among the three species examined. These results suggest that CC is involved in calcium uptake in freshwater teleosts and that both intra- and interspecific differences in the rates of calcium uptake can be accounted for by variability in the surface area of exposed CCs on the gill epithelia.  相似文献   
64.
Gill and liver microsomal Na+/K+-adenosine triphosphatase (ATPase) activities, body weight, and several blood parameters were measured in marble gobies held in freshwater, in air on wet filter paper for 7 days and three days after return to freshwater following 7 days in air. During the 7 days in air, body weight, and blood Na+ and K+ concentrations remained unchanged. During the same period, however, mean specific activity of the gill ATPase fell 79% while liver ATPase specific activity was unchanged. When these fish were returned to water the specific activity of the gill ATPase returned to values seen in freshwater gobies within 3 days. Several changes were also noted in the characteristics of the ATPase in the fish held in air.  相似文献   
65.
AIMS: To study the development and progression of lesions produced following experimental inoculations of possums with Bacille Calmette-Guérin (BCG) Pasteur Strain 1173P2 and to compare these with lesions that occurred following natural Mycobacterium bovis infection.

METHODS: Possums were inoculated with 5 x 106 colony forming units (cfu) of BCG via the intra-dermal (I/D) route into the dorsum of the neck (n=38) or the left brachium (n=7), orally (n=10), via the endo-bronchial (E/B) route (n=12), or intravenously (I/V) (n=10, half of which received 5 x 106 cfu and half of which received 5 x 107 cfu of BCG). The possums were humanely killed between 1–4 weeks post inoculation (p.i.), and the nature and distribution of lesions examined grossly and histopathologically.

RESULTS: The distribution of lesions following I/D inoculation via either route was similar to that of the natural disease, but there were few lesions in the lung. Endo-bronchial inoculation resulted in pulmonary disease but produced few lesions outside the respiratory tract. Lesions produced by I/V inoculation were similar in distribution to those seen in terminally ill tuberculous possums. No lesions were produced following oral inoculation. Regression of lesions commenced after 3 weeks p.i.

CONCLUSIONS: Although the phenomenon of lesion resolution restricts the use of BCG to the study of early lesion development, it avoids the overwhelming disease induced using M. bovis and thus allows the early phases of the development and progression of tuberculosis in this species to be observed. Intra-dermal inoculation produced evidence that infection through the skin is associated with lesions in superficial lymph nodes, whereas pulmonary disease was associated with E/B inoculation. The results are consistent with the hypothesis that both percutaneous and respiratory routes are important in natural infection of possums with M. bovis.  相似文献   
66.
AIM: To compare the rectal and I/V administration of tramadol in dogs, to assess both its pharmacokinetic properties and absolute bioavailability.

METHODS: After rectal administration via suppositories and I/V injection of tramadol (4 mg/kg), the concentration of tramadol and its main metabolites, O-desmethyl-tramadol (M1), N-desmethyl-tramadol (M2) and N,O-didesmethyl-tramadol (M5), were determined in plasma, using high-performance liquid chromatography (HPLC). A balanced cross-over study was used, involving six male Beagle dogs.

RESULTS: Plasma concentrations after rectal and I/V administration were fitted on the basis of mono- and bi-compartmental models, respectively. Following rectal administration tramadol was detected from 5 minutes up to 10 hours, in lesser amounts than M5 and M2, while M1 was detected in negligible amounts. Following I/V administration tramadol was detected up to 10 hours, M2 and M5 were detected at similar concentrations, and M1 was present at low concentrations. The area under the curve (AUC) of the three metabolites did not differ significantly after either route of administration of tramadol. The absolute bioavailability of tramadol via rectal administration was 10 (SD 4)%.

CONCLUSIONS: After rectal administration of tramadol suppositories, absorption of the active ingredient was rapid, but its metabolism quickly transformed the parent drug to high levels of M2 and M5.

CLINICAL RELEVANCE: In the dog, rectal pharmaceutical formulation of tramadol would have a different pharmacokinetic behaviour than in humans.  相似文献   
67.
AIMS: To genotype Campylobacter fetus subsp. fetus isolates cultured from sheep abortions submitted to diagnostic laboratories in New Zealand during the year 2000 breeding season. To compare the types found nationally with those found in the Hawke' Bay region in 1999, and strains held in the New Zealand Reference Culture Collection, Medical Section (NZRM) from a study published in 1987.

METHODS: Campylobacter fetus subsp. fetus isolates cultured by veterinary diagnostic laboratories in the year 2000 breeding season, from sheep abortions from throughout New Zealand, were typed using pulsed-field gel electrophoresis (PFGE). In addition, seven freeze-dried C. fetus subsp. fetus isolates (strain numbers 2939–2945) from the NZRM, representing restriction types a–g found amongst sheep abortion isolates in a study published in 1987, were typed using PFGE.

RESULTS: In total, 293 C. fetus subsp. fetus isolates from 200 farms were obtained from veterinary diagnostic laboratories. Twenty-two distinct PFGE profiles were identified amongst the isolates. PFGE type B1 was predominant in each region of New Zealand and was identified from 66% of farms overall. Of the C. fetus subsp. fetus restriction types a–g lodged with the NZRM, 3/7 had PFGE profiles indistinguishable from profiles found in the current study. The other four restriction types had PFGE profiles that were unique but similar to those found in the current study.

CONCLUSIONS: PFGE type B1 was predominant amongst the C. fetus subsp. fetus isolates cultured from sheep abortions in each region of New Zealand in the year 2000, as was found in Hawke' Bay in 1999. The similarity between PFGE profiles of C. fetus subsp. fetus sheep abortion isolates from 1987 and 2000, and the relative prevalence of the PFGE groups, suggests that there has been no major genotypic shift in the population of C. fetus subsp. fetus implicated in sheep abortion in New Zealand during this time.  相似文献   
68.
Pasteurella haemolytica leukotoxin is cytotoxic to bovine leukocytes, causing increased cell membrane permeability, osmotic swelling, release of cytosolic proteins and cell lysis. These studies were designed to test if leukotoxin causes release of the cytoskeletal protein, actin, from bovine leukemia cells and if purified actin-influenced bacterial growth or leukotoxin production. Culture supernatants caused a 7-fold decrease in viability of bovine leukemia cells and increased cell permeability that was accompanied by release of beta-actin into the cell culture supernatant. Exposing P. haemolytica to purified actin solutions induced the conversion of monomeric G-actin to polymerized F-actin. This conversion was partially inhibited by bovine P. haemolytica immune, but not pre-immune, serum. Loss of streptomycin resistance following treatment of the organism with acridine orange ablated the polymerizing activity. Incubation of P. haemolytica in the presence of purified F-actin did not affect growth but resulted in culture supernatant that had 3.0-3.9-fold greater leukotoxicity compared to medium alone or medium containing G-actin, heat-denatured actin or albumin. The effect of actin on leukotoxicity was concentration-dependent and directly associated with increases in secreted leukotoxin. The interaction between P. haemolytica and actin is potentially detrimental to the host by inducing polymerization of actin into insoluble filaments and by enhancing leukotoxicity.  相似文献   
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