Inducible nitric oxide synthase expression in Leishmania-infected dog macrophages

Nitric oxide (NO) production by the inducible NO synthase (iNOS or NOS2) represents one of the main microbicidal mechanisms of murine macrophages, but its role in other animal models is poorly investigated. Therefore, the aim of this work was to evaluate NOS2 expression in dog macrophages infected with Leishmania infantum. Macrophages obtained from peripheral blood of healthy dogs were activated with recombinant human interferon (rhIFN)-γ and bacterial lipopolysaccharide (LPS) and then infected with L. infantum promastigotes, zymodeme MON1. For the immunofluorescence assay fixed macrophages were incubated with polyclonal rabbit anti-NOS2 and then with rhodamine F(ab′)₂ goat anti-rabbit IgG. For immunoblotting, cell lysates were submitted to SDS–PAGE and blots were incubated with polyclonal rabbit anti-NOS2 and then with horseradish peroxidase-conjugated goat anti-rabbit IgG. Results demonstrated that L. infantum-infected cells, after stimulation with rhIFN-γ and LPS, displayed high levels of fluorescence for the NOS2 in their cytoplasm, unlike unstimulated uninfected macrophages. In western blotting, polyclonal anti-NOS2 reacted specifically with a protein band corresponding to 130 kDa. The signal produced in Leishmania-infected cells stimulated with rhIFN-γ and LPS was higher than that produced in Leishmania-infected unstimulated cells. No band was detected in cellular lysates from uninfected unstimulated cells. These results indicate that dog macrophages can express NOS2, and suggest a role for IFN-γ and LPS in NOS2 induction also in this animal model.     

Inducible nitric oxide synthase expression in Leishmania-infected dog macrophages

Nitric oxide (NO) production by the inducible NO synthase (iNOS or NOS2) represents one of the main microbicidal mechanisms of murine macrophages, but its role in other animal models is poorly investigated. Therefore, the aim of this work was to evaluate NOS2 expression in dog macrophages infected with Leishmania infantum. Macrophages obtained from peripheral blood of healthy dogs were activated with recombinant human interferon (rhIFN)-γ and bacterial lipopolysaccharide (LPS) and then infected with L. infantum promastigotes, zymodeme MON1. For the immunofluorescence assay fixed macrophages were incubated with polyclonal rabbit anti-NOS2 and then with rhodamine F(ab′)₂ goat anti-rabbit IgG. For immunoblotting, cell lysates were submitted to SDS–PAGE and blots were incubated with polyclonal rabbit anti-NOS2 and then with horseradish peroxidase-conjugated goat anti-rabbit IgG. Results demonstrated that L. infantum-infected cells, after stimulation with rhIFN-γ and LPS, displayed high levels of fluorescence for the NOS2 in their cytoplasm, unlike unstimulated uninfected macrophages. In western blotting, polyclonal anti-NOS2 reacted specifically with a protein band corresponding to 130 kDa. The signal produced in Leishmania-infected cells stimulated with rhIFN-γ and LPS was higher than that produced in Leishmania-infected unstimulated cells. No band was detected in cellular lysates from uninfected unstimulated cells. These results indicate that dog macrophages can express NOS2, and suggest a role for IFN-γ and LPS in NOS2 induction also in this animal model.     

Treatment of renal nephroblastoma in an adult dog

An 8-year-old Labrador retriever was diagnosed with a unilateral malignant nephroblastoma and hypertrophic osteopathy. The histopathologically malignant tumor was confined to the renal capsule, but the sarcomatous component was anaplastic, resulting in its classification as a Stage I tumor with unfavorable histopathology. The dog was treated with unilateral nephrectomy, vincristine, and doxorubicin. This dog has remained disease free for >25 months. Reported treatments of renal nephroblastoma in the dog have not described disease-free intervals of >8 months.     

日粮铜对肉鸡肾脏一氧化氮产生及一氧化氮合酶活性的影响

铜是动物体内一种必需的微量元素,在多种代谢途径中有重要的生物学作用.早期的研究结果表明,提高饲料中铜的含量,可以促进动物生长.但是过量添加铜也可以损害肝脏、肾脏等器官[1-2].一氧化氮(NO)作为一种强有力的内皮细胞舒血管因子,其功能已越来越受到人们的重视.NO对肾脏具有保护和损伤的双重作用.一方面具有扩张动脉,抑制血小板粘附、聚集,抗血栓形成,疏通微循环,增加供血,保护细胞的作用.     

一氧化氮在三氧化二砷抑制马立克病病鸡肾脏肿瘤生长中的作用

为了探讨一氧化氮(NO)在三氧化二砷(As2O3)抑制马立克病病鸡肾脏肿瘤生长中的作用,复制了鸡马立克病病例模型,通过腹腔注射As2O3,于35 d4、0 d与45 d观察病理学改变,检测肾脏肿瘤组织NO含量、T-NOS、cNOS及iNOS的活性和iNOS mRNA的表达水平。结果表明As2O3能够显著抑制肾脏肿瘤生长,降低肿瘤组织内的NO含量、T-NOS、cNOS及iNOS活性和iNOS mRNA表达水平,并呈现时间效应。揭示NO在As2O3抑制MD病鸡肾脏肿瘤生长中的作用发挥着重要作用。     

Role of tumor necrosis factor-alpha and nitric oxide in luteolysis in cattle

Although prostaglandin (PG) F2alpha is known to be a principal luteolytic factor, its action on the bovine corpus luteum (CL) is mediated by other intra-ovarian factors. Tumor necrosis factor-alpha (TNFalpha) and its specific receptors are present in the bovine CL with the highest expressions at luteolysis. TNFalpha in combination with interferon-gamma reduced progesterone (P4) secretion, increased PGF2alpha and leukotriene C4 (LTC4) production, and induced apoptosis of the luteal cells in vitro. Low concentrations of TNFalpha caused luteolysis, which resulted in a decreased level of P4, and increased levels of PGF2alpha, LTC4 and nitrite/nitrate (stable metabolites of nitric oxide-NO) in the blood. Inhibition of local NO production counteracts spontaneous and PGF2alpha-induced luteolysis. Therefore, NO is a likely candidate for the molecule that mediates PGF2alpha and TNFalpha actions during luteolysis. Both PGF2alpha and TNFalpha increase NO concentrations in blood, and stimulate NO synthase expression on protein level in the bovine CL cells. NO stimulates PGF2alpha and LTC4 secretion, inhibits P4 production and reduces the number of viable luteal cells. TNFalpha and NO induce apoptotic death of the CL by modulating expression of bcl-2 family genes and by stimulating expression and activity of caspase-3. The above findings indicate that TNFalpha and NO play crucial roles in functional and structural luteolysis in cattle.     

Dilated cardiomyopathy and sinoatrial dysfunction in an Estrela mountain dog

A 1 yr old male Estrela mountain dog was evaluated as a part of a screening program for dilated cardiomyopathy. The dog came from a family with a history of dilated cardiomyopathy but was asymptomatic. Occult dilated cardiomyopathy and sino-atrial dysfunction were diagnosed based on echocardiography and electrocardiography. These two disorders may be associated given that related dogs have been diagnosed with the same disorders. The dog has remained asymptomatic for 4 years following initial evaluation.     

L-硝基精氨酸对阿尔茨海默症小鼠脑海马nNOS阳性神经元分布、NOS活性及NO含量变化的影响

为了研究D-半乳糖联合铝诱导的小鼠阿尔茨海默症(AD)脑海马一氧化氮合酶(NOS)活性和一氧化氮(NO)含量的变化及L-NNA和盐酸多奈哌齐对其变化的影响,探讨NO在阿尔茨海默症中的作用机制及2种药物对脑神经元的保护作用。选取2月龄健康昆明小鼠160只,体质量(20±2)g,随机分为正常对照组、模型组、盐酸多奈哌齐治疗组及L-NNA治疗组,利用D-半乳糖联合三氯化铝建立小鼠AD模型,应用生化检测技术测定各组脑海马在造模后每周NOS活性及NO含量。结果表明,模型组海马内NOS活性开始呈缓慢升高,从第4周开始呈显著升高,保持较高含量至12w造模结束;两治疗组脑海马NOS活性在各时间点极显著或显著低于模型组(P0.01或P0.05),并且L-NNA在4~8周时降低脑海马NOS活性的程度好于盐酸多奈哌齐治疗组(P0.05);NO含量的变化随着NOS活性的变化而变化;利用SABC免疫组织化学方法检测各组脑海马神经型NOS(nNOS)阳性神经元,发现模型组脑海马nNOS阳性神经元密度降低,细胞着色变淡,胞体截面积和最长突起长度变小,经过治疗后神经元密度增加,胞体截面积和最长突起长度显著改善(P0.05)。结果提示NO参与了AD形成过程,高浓度的NO能发挥神经毒性作用损害脑组织;L-NNA通过抑制NOS的活性,降低了脑海马NO的含量,对阿尔茨海默症中海马神经元具有明显的保护作用。     

Role of nitric oxide in regulating the ductus arteriosus caliber in fetal rats

The role of nitric oxide (NO) on the ductus arteriosus (DA) patency was examined in fetal rats at various stages of gestation. N(G)-nitro-L-arginine methyl ester (L-NAME, 50 mg/kg, i.p.), an NO synthase (NOS) inhibitor, or indomethacin (3 mg/kg, p.o.), a cyclooxygenase inhibitor, was administered at 3 hr before cesarean section to pregnant rats ranging from day 17 to day 21 of gestation. Dams were decapitated and the fetuses were obtained by cesarean section. The fetuses were rapidly frozen in an acetone-dry ice mixture. Using rapid-freezing and shaving methods, the calibers of the DA and pulmonary artery were measured. The constrictive effect of L-NAME on the fetal DA caliber was stronger than that of indomethacin in 19-day-old and immature fetuses. In near-term fetuses, the constrictive effects of L-NAME were reduced, while indomethacin caused marked DA constriction. We conclude that endogenous NO may play a major role in regulating the patency of the DA in earlier fetal stages, while dilator prostaglandins may play a greater role in regulating the ductal patency in the near-term fetus.     

Peripheral neuropathy and hypotension in a diabetic dog

Peripheral neuropathy and hypotension were found in a diabetic dog with profound weakness. Insulin therapy controlled the diabetes mellitus. As the blood glucose was normalized, the neurologic signs and hypotension resolved, suggesting a causal relationship.     

Transvenous pacemaker leads in the dog: an experimental study

Tined transvenous pacing leads were inserted into nine healthy large-breed dogs as part of an experimental study evaluating an implantable defibrillator. The pacing leads were used to induce ventricular fibrillation on the day of insertion, two and four weeks after insertion and then monthly. Despite daily running exercise on and off a leash, the tined leads remained firmly anchored to the right ventricular apex for the full experimental period of up to 12 months. Apart from mechanical endocarditis of the tricuspid valve, and partial penetration of the ventricular wall in one dog, problems associated with the pacing leads were not encountered. The use of tined leads and careful technique may minimise the likelihood of transvenous lead displacement.     

Progressive oropharyngeal dysfunction in a dog

A dog with an acquired, progressive oropharyngeal dysphagia also had a myopathy-neuropathy. It was clinically similar to criocopharyngeal achalasia, and could easily have been confused with it, even with fluoroscopic evaluation. Conservative medical therapy was instituted since cricopharyngeal myotomy could have caused severe aspiration and death. Resolution was apparently due to anti-inflammatory therapy.     

Role of parathyroid hormone in the anemia of chronic terminal renal dysfunction in dogs

Terminal renal dysfunction (TRD) was induced in 2 groups of dogs by partial surgical ablation of the kidney. Dogs of a control group and of 1 of the TRD groups were maintained on a diet containing normal phosphorus concentration, whereas dogs of the other TRD group were maintained on a low-phosphorus diet. Mild anemia developed in dogs of both TRD groups and could not be attributed to iron deficiency, increased erythrocyte concentration of 2,3-diphosphoglycerate, or absolute deficiency of erythropoietin (EP). Subsequently, all dogs were acutely depleted of approximately 25% of their blood volume. Erythropoietin concentration in dogs of the TRD groups was lower than that of controls, however, erythroid regenerative capacity was comparable with that of control dogs when plasma parathyroid hormone (PTH) concentration was lowered by reduced dietary intake of phosphorus. The PCV in dogs of the chronic TRD groups had a slight positive correlation with serum EP concentration, and a significant (P less than 0.05) negative correlation with plasma PTH and serum phosphorus and creatinine concentrations, using a correlation matrix. There was no longer a significant correlation between plasma PTH concentration and PCV after controlling for serum creatinine concentration by use of a multiple linear regression analysis. A significant (P less than 0.05) negative correlation also was observed between plasma PTH and serum EP concentrations, but not between serum EP and phosphorus or creatinine concentrations. Significance of the EP and PTH association was reduced when analyzed, using a multiple linear regression analysis that included serum creatinine values.(ABSTRACT TRUNCATED AT 250 WORDS)     

The pentobarbital anesthetized dog: an animal model for assessing chemically induced changes in renal function and ultrastructure

An experimental procedure was devised using the pentobarbital-anesthetized dog that could be used for the comprehensive evaluation of the renal effects of chemicals. After IV or renal arterial administration of 0.9% saline solution (vehicle), 12 renal function determinants were continuously monitored for periods of 2 and 6 hours. At the completion of the 2 or 6 hours of study, the kidneys of a number of dogs (usually between 1 and 7) in each vehicle-treated group were subjected to a modification of the intravascular perfusion-of-fixative technique to evaluate the ultrastructural status of the outer cortical, inner cortical, and outer medullary tissue. The remaining dogs (at least 3) in each vehicle-treated group were given a nonnephrotoxic, but maximally effective, diuretic dose of ethacrynic acid, which enabled an assessment of the functional integrity of the thick ascending limb of Henle's loop. Renal function and glomerular and tubular ultrastructure remained stable in the pentobarbital-anesthetized dog for up to 6 hours after administration of vehicle. Sustained infusion of inulin (included in the procedure to estimate glomerular filtration rate) throughout the duration of the experiments, and pentobarbital anesthesia of various durations did not alter the morphologic status of the canine nephron. The procedure used for the renal perfusion of fixative circumvented any manipulation of the kidneys before fixation and allowed for the acquisition of normal (unaltered) appearing tissue from all areas of the kidneys. The responses of pentobarbital-anesthetized dogs to ethacrynic acid administration were similar when given 2 and 6 hours after the vehicle administration.(ABSTRACT TRUNCATED AT 250 WORDS)