Relationship between oxidative stress and clinical–pathological aspects in dogs experimentally infected with Rangelia vitalii

The aim of this study was to evaluate lipid peroxidation, protein oxidation and activity of enzymes that are indicators of oxidative stress in Rangelia vitalii infection in dogs. Animals were divided into two groups: negative control (n = 5) and infected with R. vitalii (n = 7). After inoculation, the parasitemia was estimated daily by microscopic examination of smears. Lipid peroxidation (TBARS) and advanced oxidation protein products (AOPP); and delta-aminolevulinate dehydratase (δ-ALA-D), superoxide dismutase (SOD) and catalase (CAT) activities in blood were evaluated. The samples were collected at days 10 and 20 post-inoculation (PI). TBARS and AOPP levels were higher in the infected group in both analyzed periods (P < 0.01). The δ-ALA-D activity was reduced in blood of dogs infected with R. vitalii on days 10 and 20 PI. SOD activity was significantly increased (P < 0.01) in the blood of dogs infected with R. vitalii at days 10 and 20 PI, while CAT activity was significantly increased (P < 0.01) only at day 20 PI when compared to non-infected animals. A positive correlation was observed between the degree of parasitemia and TBARS and AOPP levels and activity of antioxidant enzymes. The δ-ALA-D activity was negatively correlated with the degree of parasitemia. Based on the increased levels of TBARS, AOPP, SOD and CAT activities, and inhibition δ-ALA-D activity, we concluded that dogs experimentally infected with R. vitalii develop a state of redox unbalance and that these changes might be involved in the pathophysiology of disease.     

Thrombocytopenia and platelet activity in dogs experimentally infected with Rangelia vitalii

The aim of this study was to evaluate the platelet count, coagulation time and platelet activity in dogs experimentally infected with Rangelia vitalii during the acute phase of the disease. For this study, 12 young dogs (females) were used, separated in two groups. Group A (uninfected control) was composed by healthy dogs (n=5), and group B consisted of R. vitalii-infected animals (n=7). After being inoculated with R. vitalii-infected blood, animals were monitored by blood smear examinations, which showed intra-erythrocytic forms of the parasite five days post-inoculation (PI). Blood samples were collected on days 0, 10, 20 and 30 PI. The material collected was placed in tubes containing EDTA for quantification of platelets, citrate anticoagulant platelet aggregation, and measuring the clotting time. Right after blood collection on days 10 and 20 PI, dogs were anesthetized for collecting bone marrow samples. A significant reduction (P<0.01) of the number of platelets was observed in R. vitalii-infected blood, when compared with uninfected dogs on days 10 and 20 PI. Additionally, macro-platelets were observed only in infected dogs. Prothrombin time and activated partial thromboplastin time did not differ between infected and uninfected dogs. The megakaryocyte count increased (P<0.01) significantly in infected dogs when compared with uninfected ones on days 10 and 20 PI. Platelet aggregation decreased (P<0.01) significantly in infected dogs in comparison to the control on days 10 and 20 PI. Therefore, rangeliosis in dogs causes a severe thrombocytopenia during the acute phase of infection. This platelets reduction probably occurred due to splenic sequestration and/or immune-mediated thrombocytopenia.     

Acetylcholinesterase activity and lipid peroxidation in the brain and spinal cord of rats infected with Trypanosoma evansi

Neurological and locomotor clinical signs are described in animals infected with Trypanosoma evansi. These disturbances may be related to changes in the amount of acetylcholine (neurotransmitter) in the synaptic cleft. Therefore, changes in acetylcholinesterase (AChE) activity and lipid peroxidation in brain and spinal cord of T. evansi-infected rats were investigated. Each rat was intraperitoneally infected with 10(6) trypomastigotes kept in fresh (group A; n=13) and cryopreserved blood (group B; n=13). Thirteen served as uninfected (not-infected; group C). In days 4 and 30 post-infection (PI) the rats were anesthetized and subsequently decapitated to obtain the brain and the spinal cord (between vertebrae L1 and S2). The brain was removed and dissected (cerebellum, cerebral cortex, striatum and hippocampus) to measure the activity of AChE and lipid peroxidation, determined by TBARS levels. To verify if T. evansi was present in the central nervous system (CNS), brain structures of three rats of each group were processed by PCR T. evansi-specific. AChE activity was significantly increased in all brain structures and decrease in spinal cord in infected rats in 4 PI (P<0.05). The levels of TBARS were decreased in the brain structures, differently from spinal cord, which showed increased lipid peroxidation in 4 PI. The AChE activity in striatum, cerebral cortex, hippocampus and spinal cord reduced concomitantly with the increase of the enzyme in cerebellum of the infected rats (P<0.05), and the TBARS levels increased in cerebellum, striatum and spinal cord of infected rats compared to non-infected animals in 30 PI. The PCR was positive for T. evansi in all structures of the brain, confirming the presence of the parasite in the CNS. Based on the results, we conclude that the changes in AChE activity and lipid peroxidation in the CNS are induced by infection with T. evansi, suggesting that the parasite interferes with the cholinergic neurotransmission in this experimental condition.     

Increased generation of superoxide in erythrocytes infected with Babesia gibsoni.

The present study was conducted to clarify the mechanism underlying the oxidative process in erythrocytes infected with Babesia gibsoni. The parasite B. gibsoni was cultured together with erythrocytes from normal dogs for 7 days. When parasitemia reached 12.0-13.4% at Day 7. the production of superoxide in erythrocytes was significantly higher in the parasitized culture than in the control culture (p<0.005). The concentration of thiobarbituric acid reactive substances (TBARS) in erythrocytes in parasitized culture was also significantly increased compared with the control culture (p<0.005), indicating that lipid peroxidation was greater in infected erythrocytes than in non-infected cells. In addition, the rates of superoxide generation in the blood of B. gibsoni-infected dogs were also significantly higher than in non-infected dogs (p<0.001). These results indicate that superoxide anions are increased in erythrocytes parasitized with B. gibsoni. and suggest that oxidative damage, due to lipid peroxidation, might be caused in host erythrocytes by the parasite.     

Detection and molecular characterization of a canine piroplasm from Brazil

In the beginning of the 20th century, a new canine disease was reported in Brazil under the name "nambiuvú", whose etiological agent was called Rangelia vitalii, a distinct piroplasm that was shown to parasitize not only erythrocytes, but also leucocytes and endothelial cells. In this new century, more publications on R. vitalii were reported from Brazil, including an extensive study on its ultrastructural analysis, in addition to clinical, pathological, and epidemiological data on nambiuvú. However, a molecular analysis of R. vitalii has not been performed to date. In the present study, we performed molecular phylogenetic analyses of R. vitalii based on fragments of the genes 18S rRNA and the heat shock protein 70 (hsp70), amplified by PCR performed on blood samples derived from five clinical cases of dogs presumably infected with R. vitalii in southern Brazil. In addition, we examined Giemsa-stained thin blood smears from these same dogs. DNA sequences (604-bp) of the 18S rRNA gene obtained from the five dogs were identical to each other, and by Blast analysis, this sequence shared the highest degree of sequence identity (95%) with Babesia sp. China-BQ1. DNA sequences (1056-bp) of the hsp70 gene obtained from the five dogs were identical to each other, and by Blast analysis, this sequence shared the highest degree of sequence identity (87%) with Babesia bigemina. Phylogenetic analyses inferred from either of the two genes resulted in the newly genotype being placed in the Babesia spp. sensu stricto clade with very high bootstrap support (95-100%) in three analyses (Neighbor-Joining, Maximum parsimony, and Maximum likelihood). Giemsa-stained thin blood smears from the dogs were shown to contain piroplasm organisms within erythrocytes, monocytes and neutrophils (individual forms), and schizont-like forms within neutrophils, in accordance with literature reports of R. vitalii. Based on these results, we conclude that R. vitalii, the etiological agent of "nambiuvú" in southern Brazil, is a valid species of piroplasm. Further studies are required to evaluate the validity of the genus Rangelia.     

Alterations of erythrocyte antioxidant mechanisms: antioxidant enzymes, lipid peroxidation and serum trace elements associated with anemia in bovine tropical theileriosis

In order to investigate the alterations of erythrocyte protective antioxidant mechanisms, lipid peroxidation and trace elements associated with anemia in bovine tropical theileriosis, an infected group comprised of 50 crossbred Holstein cattle, about 1-2 years old, naturally infected with Theileria annulata, were divided into 4 subgroups according to their parasitemia rates (<1%, 1-3%, 3-5%, >5%) and also 10 healthy cattle as control were selected. Blood samples were taken and hematological parameters, the activities of antioxidant enzymes including superoxide dismutase (SOD), glutathione peroxidase (GPX) and catalase and serum concentrations of some antioxidant trace elements (copper, iron, zinc, manganese and selenium) were measured. As an index of lipid peroxidation, the level of Malondialdehyde (MDA) was also determined. The results showed a conspicuous decrease in the activities of SOD, GPX and catalase (P<0.01), and a significant decrease in the serum concentrations of Cu, Zn, Mn and Se in cattle with higher than 1% parasitemia (P<0.05) compared to the control. In addition, remarkable elevations in the MDA level (P<0.01) and serum concentration of iron (P<0.05) were observed in the infected animals. These findings pointed to the occurrence of exacerbating oxidative injuries to erythrocytes during parasitemia. Furthermore, it can be concluded that infection with T. annulata can interfere with protective antioxidant mechanisms of RBCs against oxidative damages, which promote the development of anemia.     

Anti-oxidative status and semen quality during cooled storage in stallions

Activity of the anti-oxidative enzymes glutathione peroxidase (GSH-Px), superoxide dismutase (SOD) and catalase (CAT), content of thiobarbituric acid reactive substances (TBARS) and SH-groups were determined in native stallion semen (n = 8 stallions). Semen was then diluted in Kenney extender, EquiPro((R)) extender either with or without addition of N-acetyl cysteine or phosphate-buffered saline (PBS) and stored for 72 h at 5 degrees C. Correlations between initial activity of enzymes and development of semen motility and membrane integrity were calculated. Activities of GSH-Px, SOD and CAT immediately after semen collections were 10.0 +/- 0.6 picokatals, 0.40 +/- 0.03 SOD units and 0.70 +/- 0.05 nanokatals/10(6) spermatozoa respectively. TBARS content was 0.06 +/- 0.01 nmol and SH-group content 1.7 +/- 0.5 mmol/10(6) spermatozoa. The loss of motile spermatozoa during storage did not differ between extenders. N-acetyl cysteine had no effect on semen motility and membrane integrity. The loss in membrane-intact spermatozoa was highest (P < 0.05) in semen diluted in PBS. Motility and membrane integrity after addition of extender were positively correlated with GSH-Px and CAT, indicating that anti-oxidative mechanisms contribute to the initial high percentage of motile and membrane-intact spermatozoa. However, in these samples the decrease in semen quality was most pronounced. No correlations existed between initial activity of anti-oxidative enzymes, peroxidation products and semen quality during storage. This indicates that once extender has been added, peroxidative damage to sperm membranes is not the predominant cause of losses in semen quality.     

Oxidative stress parameters in silver catfish (Rhamdia quelen) juveniles infected with Ichthyophthirius multifiliis and maintained at different levels of water pH

The aim of this study was to determine oxidative stress parameters in the liver, gill and muscle of silver catfish juveniles infected with Ichthyophthirius multifiliis and maintained at pH 5.0 or 7.0 for three days. Juveniles were infected by adding one I. multifiliis-infected juvenile and water containing theronts to tanks. After the appearance of white spots on the skin, infected juveniles exposed to pH 5.0 and 7.0 showed significantly higher thiobarbituric acid reactive substances (TBARS) levels in the liver and gills compared to uninfected juveniles. Liver of infected juveniles exposed to pH 7.0 showed higher catalase (CAT) and lower glutathione-S-transferase (GST) activities, but those maintained at pH 5.0 showed significantly higher GST activity than uninfected juveniles. The gills of infected juveniles showed significantly higher CAT (day two) and GST activity at both pH 5.0 and 7.0 compared to uninfected juveniles. Muscle of infected juveniles showed significantly lower CAT and GST activity and TBARS levels (at day three) when maintained at both pH 5.0 and 7.0 compared to uninfected juveniles. In conclusion, I. multifiliis infection induces liver and gill damage via lipid peroxidation products in silver catfish, but higher antioxidant enzyme activity could indicate a greater degree of protection against this parasite.     

Lymphocyte subsets and specific IgG antibody levels in clindamycin-treated and untreated dogs experimentally infected with Babesia gibsoni

This study was carried out to clarify the role of lymphocyte subpopulations and Babesia-specific antibody on the treatment of clindamycin in dogs infected with B. gibsoni. Ten beagle dogs were divided into two groups: an untreated group (5 dogs) and a clindamycin-treated group (5 dogs), which was administered clindamycin at 25 mg/ kg body weight, per os, q 12 hr from 7 days to 21 days post-infection (PI). On the acute stage of infection, clindamycin treatment resolved anaemia and other clinical findings. There were no significant differences between treated and untreated dogs either in parasitemia levels or Babesial IgG antibody levels. However, morphological changes that indicated degeneration in the majority of parasites were observed. The numbers of CD4(+) showed a significant increase in treated dogs, especially after treatment. On the chronic stage, CD4(+) cells maintained high level both of the treated and untreated dogs. Although parasitemia maintained low level, their relapses were occurred on the 49th day PI in treated dogs and on the 42nd and 63rd PI in untreated dogs. A rapid humoral antibody response was observed in treated dogs, however, lower humoral antibody responses in untreated dogs after relapses. The antibody levels of treated dogs were significantly higher than those of untreated dogs. These results suggested that clindamycin might not eliminate rapidly parasites from peripheral blood, but damage parasites, which might stimulate efficiently humoral and cellular immunity against Babesia infection, and result in an improvement of clinical conditions.     

Enzymatic antioxidant defense in isolated rat hepatocytes exposed to cadmium

The aim of the study was the evaluation of cadmium effects on the activity of antioxidant enzymes in rat hepatocytes. The studies were conducted with isolated rat hepatocytes incubated for 1 or 2 hours in a modified (deprived of carbonates with phosphates) Williams' E medium (MWE) in the presence of cadmium chloride (25, 50 and 200 microM). Hepatocytes incubated in the MWE medium without cadmium chloride were used as a control. The application of the modified Williams' E medium allowed for the appearance of cadmium compounds in a soluble form that is indispensable for suitable estimation of its toxic action. There were evaluated markers of the oxidative stress such as: concentration of thiobarbiturate reactive substances (TBARS)--proportional to the level of lipid peroxidation, concentration of reduced glutathione (GSH), and the activity of antioxidant enzymes, including superoxide dismutase (SOD1 and SOD2), catalase (CAT), total glutathione peroxidase (GSHPx), selenium--dependent glutathione peroxidase (SeGSHPx), glutathione transferase (GST) and glutathione reductase (GSHR). Alterations of antioxidant enzymes activity, the level of TBARS and GSH in isolated rat hepatocytes caused by cadmium in vitro, were shown to depend on the concentration and time of exposure of cells to this metal. The increased level of TBARS and GSH was observed as well as changes in the activity of antioxidant enzymes. The activity of SOD isoenzymes and CAT was increased, whereas GSHPx and GST were decreased. These results indicate that cadmium induces oxidative stress followed by alterations in the cellular antioxidant enzyme system in isolated rat hepatocytes.     

Comparative efficacy assessment of pentamidine isethionate and diminazene aceturate in the chemotherapy of Trypanosoma brucei brucei infection in dogs

The chemotherapeutic efficacy of diminazene aceturate (Berenil)--a standard veterinary trypanocide and pentamidine isethionate (PMI)--a human trypanocide was compared in dogs experimentally infected with Trypanosoma brucei brucei. Also, the activities of the drugs on some serum liver enzymes were evaluated before and after treatment to ascertain the relative safety of the drugs. Fifteen local dogs (mongrels) were used for the study. Three of the dogs were uninfected controls, and twelve were infected with a stock of T. brucei brucei. Three of the infected dogs were untreated controls, three were given diminazene aceturate (DA) at 7 mg/kg body weight intramuscularly (i/m), another three received pentamidine isethionate (PMI) at 4 mg/kg i/m on days 14, 17, 19, 27, 29, and 31 post infection (PI) and the remaining three dogs were also given same dose of PMI on days 14, 16, 18, 20, 22, 24 and 26 PI. Both trypanocides effectively cleared the parasites from the blood of the infected treated dogs. However, the infection subsequently relapsed at day 42 PI in one of the dogs in the DA treated group which later died at day 70 PI. Relapse infection was not recorded with the PMI treated groups although two dogs died in the PMI treated group II (treatment at days 14, 17, 19, 27, 29, and 31 PI) without showing relapsed parasitaemia. The packed cell volume (PCV), red blood cell (RBC) count, and haemoglobin (Hb) level which decreased significantly following infection, were reversed by the trypanocidal treatment. The reversal in the red cell values was faster in the PMI treated groups than in the DA treated group. The serum alkaline phosphate (SAP), aspartate aminotransferase (AST), and alanine aminotransferase (ALT) levels increased following infection and drug administration. The increase in the enzyme levels was greater in the DA treated groups than PMI treated groups. It was thus concluded that PMI given at 4 mg/kg i/m at days 14, 16, 18, 20, 22, 24, and 26 PI constituted a safe and efficient trypanocide and exhibited a superior trypanocidal action than DA in T. brucei brucei infected dogs.     

Adenosine deaminase activity in serum, erythrocytes and lymphocytes of rats infected with Leptospira icterohaemorrhagiae

Leptospirosis is a systemic disease of humans and domestic animals, mainly dogs, cattle and swine. The course of human leptospirosis varies from mild to severe fatal forms and the most severe form of human leptospirosis is principally caused by Leptospira interrogans serovar icterohaemorrhagiae (L. icterohaemorrhagiae). The enzyme adenosine deaminase (ADA) plays an important role in the production and differentiation of blood cells. The aim of this study was to evaluate the activity of ADA in serum, erythrocytes and lymphocytes of rats infected with L. icterohaemorrhagiae, as compared with non-infected rats. Twenty-four adult rats, divided into two uniform groups (A and B) were used for the enzymatic assays. The animals in Group B were inoculated intraperitoneally with 2×10(8) leptospires/rat, and the rodents in Group A (control) were not-inoculated. Blood collection was performed on days 5 and 15 post-infection (PI) and the blood used to assess the ADA activity. The infection by L.icterohaemorrhagiae altered erythrocyte count, hemoglobin concentration and hematocrit, causing a decrease in all these parameters on day 15 PI. Lymphocytes decreased significantly on day 15 PI, and ADA activity in serum was inhibited in infected rats on days 5 and 15 PI and its activity in erythrocytes were increased on day 5 PI. On day 5 PI, we found an increase in ADA activity in erythrocytes of infected rats. No correlation was observed between hematocrit and erythrocyte ADA activity on days 5 and 15 PI. The ADA activity was inhibited in rats infected on day 15 PI. A positive correlation (r(2)=60) was also observed between the number of lymphocytes and ADA activity in lymphocytes on day 15 PI (P<0.05). In conclusion, our results showed that the ADA activity is altered in serum, lymphocytes and erythrocytes in experimental infection by L.icterohaemorrhagiae in rats, concomitantly with hematological parameters.     

The effect of macrophages on the erythrocyte oxidative damage and the pathogenesis of anemia in Babesia gibsoni-infected dogs with low parasitemia

The role of macrophages in the erythrocyte membrane oxidative damage and the pathogenesis of anemia in Babesia gibsoni-infected dogs with low parasitemia were investigated. Macrophages derived from peripheral blood monocytes (PBM) from B. gibsoni-infected dogs produced significantly higher chemiluminescent responses, indicating the release of reactive oxygen intermediates, than those from non-infected dogs when the cells were subjected to non-specific stimulation with phorbol 12-myristate 13-acetate (PMA) and opsonized zymosan (OZ), or infected dog erythrocyte membranes opsonized with infected dog serum. These results indicate that PBM of B. gibsoni-infected dogs with low parasitemia were highly activated compared to those of non-infected dogs. Furthermore, the membrane lipid peroxidation of normal dog erythrocytes incubated with PBM from B. gibsoni-infected dogs was significantly higher (p<0.05) than that of erythrocytes incubated with PBM from non-infected dogs when the PBM were stimulated with the opsonized membranes. These results suggest that the oxidative damage of erythrocytes observed in B. gibsoni-infected dogs with low parasitemia might be induced, in part, by reactive oxygen species released from the activated PBM. On the other hand, the present study also showed a significant increase (p<0.001) of IgG-bound erythrocytes in B. gibsoni-infected dogs compared with such erythrocytes in non-infected dogs. The increase of IgG-bound erythrocytes in infected dogs might reflect the increase of erythrocytes with oxidative damage induced by the infection with B. gibsoni. The results of the present study suggest that the increase of IgG-bound erythrocytes in the circulation of infected dogs induce a high degree of erythrocyte loss via immunological phagocytosis by activated macrophages, resulting in severe anemia in spite of low parasitemia.     

Evaluation of antioxidant status and oxidative stress in sheep naturally infected with Babesia ovis

The present study aimed to assess antioxidant status and oxidative stress in sheep naturally infected with Babesia ovis. Red blood cell (RBC) count, hemoglobin (Hb) concentration, packed cell volume (PCV), piroplasm parasitemia percentage, malondialdehyde (MDA) concentration, erythrocyte superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT) activities and total antioxidant capacity (TAC) were determined in 52 sheep naturally infected with B. ovis as well as same number of healthy sheep in West-Azerbaijan province, Iran. Microscopic examination of Giemsa-stained peripheral blood smears revealed B. ovis infection. The parasitological diagnosis was confirmed using polymerase chain reaction (PCR) analysis by amplifying a partial small subunit ribosomal RNA (ssu rRNA) gene sequence of B. ovis of 52 diseased sheep, 18 (34.61%), 11 (21.15%), 16 (30.76%) and 7 (13.48%) had <1%, 1-2%, 2-3% and >3% parasitemia, respectively. Compared to controls, the activities of erythrocyte GSH-Px, SOD, TAC and CAT showed a significant decrease, whereas the concentration of MDA in erythrocytes of infected sheep increased significantly. Parasitemia rate was positively correlated with MDA and negatively correlated with PCV, SOD, CAT, GSH-Px and TAC. Also, MDA was negatively correlated with PCV, SOD, catalase, GSH-Px and TAC. The study demonstrated that B. ovis plays an important role in the occurrence of oxidative damage to RBCs and anemia in ovine babesiosis.     

Evaluation of free radical formation associated with diagnostic ultrasound

Our objective was to evaluate kidney antioxidant status in rats subjected to an ultrasound examination. Thirty rats were divided into five groups for injection of saline (S) or anesthetic (A), and application of ultrasound using different modes, B mode, pulsed wave Doppler, and continuous wave Doppler, under anesthesia. Ultrasound was performed on days 1, 3, and 5 relative to the initiation of the experiment. Rats were then scarified on day 6. The kidney tissue thiobarbituric acid reactive substance (TBARS) level and superoxide dismutase (SOD) activity were measured. Both TBARS level and SOD activity increased, 21% and 38%, respectively, due to anesthesia (P < 0.04 for both). SOD activity increased further by a factor of 1.2 in response to ultrasound examination (P < 0.05), whereas TBARS level was not affected by Doppler and continuous wave Doppler compared to anesthesia. Increases in the level of TBARS (P < 0.03) and SOD activity (P < 0.01) were greatest when B-mode ultrasound was employed. These substances did not increase further when continuous wave Doppler was employed. The peak-negative acoustic pressure (9.16 vs. 9.74 MPa) and frequency (3.57 vs. 6.95 MHz) for B mode and pulsed wave Doppler were greater than those for continuous wave Doppler (0.22 MPa and 1.96 MHz). The estimated mechanical indexes were 4.87, 3.70, and 0.15 for B mode, pulsed wave Doppler, and continuous wave Doppler, respectively. In conclusion, anesthesia may cause tissue damage as reflected by elevated lipid peroxidation and free radical formation and ultrasound examination may amplify tissue damage through mechanical effects caused by ultrasound absorption.     

肠炎沙门氏杆菌感染雏鸭肝脏抗氧化功能的动态研究

用肠炎沙门氏杆菌感染雏鸭，研究雏鸭肝脏抗氧化功能的动态，同时，探讨药物治疗对感染雏鸭肝脏抗氧化功能的影响，测定了肝脏组织中抗氧化酶活性和丙二醛（MDA）的含量。结果表明，雏鸭肝脏超氧化物歧化酶（SOD）活性于感染12h、36h极显著升高（P〈0．01），而60h后则显著降低（P〈0．05），过氧化物酶（PoD）、过氧化氢酶（CAT）活性分别于36h、60h升高（P〈0.05或P〈0．01）。而MDA含量则于12h增加（P〈0．05），随后降低但不显著（P〉0．05），说明肝脏抗氧化功能于感染后发生异常变化，同时，用西药氟苯尼考或中草药复方制剂对人工感染肠炎沙门氏杆茵的雏鸭进行饮水给药治疗，均能一定程度上增强肝脏的抗氧化功能。结果表明，肝脏中各种抗氧化酶参与了抵御肠炎沙门氏杆菌的过程。     

Disturbance of oxidant/antioxidant equilibrium in horses naturally infected with Trypanosoma evansi

Oxidant/antioxidant equilibrium disturbance has already been reported in trypanosome infections by several authors. The present study was aimed to explore the possible oxidant/antioxidant disturbance in surra of naturally infected horses before and after treatment. Fifteen naturally infected horses were chosen to analyse erythrocytic indices, platelet counts, lipid peroxides (LPO), nitric oxide (NO), reduced glutathione (GSH), superoxide dismutase (SOD) and catalase (CAT) while six healthy animals acted as control. There was a highly significant (P<0.001) reduction in red blood cell (RBC) count, haemoglobin (Hb), packed cell volume (PCV) and platelet levels and a significant reduction in mean corpuscular haemoglobin concentration (MCHC) (P<0.05) was noticed. A highly significant increase in NO (P<0.001), a significant increase in LPO (P<0.05) and a significant decrease in GSH, SOD and CAT (P<0.05) were found. A negative correlation of RBC count with LPO (r=-0.844) and nitrate (r=-0.702) while a positive correlation with GSH (r=0.489), SOD (r=0.580) and CAT (r=0.689) was observed. All the animals were treated with Quinapyramine sulphate (3mg/kg s.c.) only once. Nine animals recovered completely without any side effects. The recovered animals were monitored and samples were collected every seven days for up to 21 days and parameters were analysed. After treatment, a significant increase in haematological parameters was noticed whereas the oxidative indices varied without any statistical significance. To conclude, the increase in oxidant parameters and decrease in antioxidant enzymes in infected horses indicates the disturbance of oxidant/antioxidant indices. There was a significant increase in post therapy haematological values, while the oxidant/antioxidant indices changed insignificantly indicating that antioxidants might be supplemented in the therapeutic regimen.     

Clinical and hematologic effects of experimental infection of dogs with recently identified Babesia gibsoni-like isolates from Oklahoma

OBJECTIVE: To characterize clinical and hematologic responses in dogs following experimental inoculation with Babesia gibsoni-like isolates from infected dogs in Oklahoma. DESIGN: Prospective study. ANIMALS: 6 mixed-breed dogs. PROCEDURE: 2 dogs were inoculated with organisms from a naturally infected dog, and 3 were inoculated with organisms from a second naturally infected dog (1 of these 3 dogs was splenectomized 1 week prior to inoculation). One dog was not inoculated. Complete blood counts were performed weekly. RESULTS: In the 5 dogs inoculated with organisms, parasites were initially detected 1 to 5 weeks after inoculation, and severity of parasitemia peaked with 1.9 to 6.0% of RBC infected by 4 to 6 weeks after inoculation. Parasitemia was easily detectable (> 0.1% of RBC infected) for 3 to 4 weeks. Clinical abnormalities included lethargy, fever, and pale mucous membranes but were mild to nearly inapparent in 2 dogs. All dogs developed regenerative anemia and marked thrombocytopenia. Thrombocytopenia developed before and lasted longer than the parasitemia. Profound but transient neutropenia was detected in some dogs. The splenectomized dog developed more severe parasitemia and anemia and more pronounced clinical abnormalities. Three dogs with intact spleens recovered without treatment. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that 2 or more genotypically distinct, but morphologically identical, small Babesia parasites can infect dogs in the United States. Compared with infection with small Babesia parasites from California, infection with these isolates resulted in less severe parasitemia and clinical abnormalities. Parasitemia was transient, indicating that identification of organisms in blood smears may be difficult in some dogs.     

Effect of deferoxamine and L-arginine treatment on lipid peroxidation in an intestinal ischaemia-reperfusion model in rats

This study investigated lipid peroxidation (LPO) changes during intestinal ischaemia-reperfusion with and without deferoxamine or L-arginine treatment. White Wistar rats were allotted into four groups as follows: sham-operated (Group SOP), ischaemia-reperfusion only (Group I/R), I/R with deferoxamine (Group D) or L-arginine (Group A) treatment. Concentration of thiobarbituric acid reactive substances (TBARS), overall concentration of malondialdehyde and 4-hydroxy-alkenals (LPO586), activities of superoxide dismutase (SOD) and glutathione peroxidase (GPX) of the jejunal homogenates were determined. The same analytes except LPO586 were assayed in RBC haemolysates. Measurements of ferric reducing ability (FRAP), total antioxidant status (TAS) and nitric oxide (NO) concentrations of plasma samples were also completed. The only significant change observed in the SOP group was an increased SOD activity after the ischaemic period. In the I/R group significant increase of intestinal LPO586 concentration was observed during hypoxia that was followed by similar changes in intestinal and RBC TBARS and plasma FRAP values upon reperfusion. In Group D the intestinal TBARS and LPO586 concentrations were significantly lower while FRAP and NO concentrations were significantly higher compared to the I/R group. At the same time RBC TBARS concentration and GPX activity significantly decreased within Group D. In Group A the intestinal LPO586 concentration was significantly lower than in the I/R group whilst RBC TBARS concentration showed a similar pattern. Plasma FRAP and NO concentration showed similar changes to those seen in Group D. It is concluded that I/R increased the LPO in the intestinal tissue and altered some parameters of plasma and RBCs, too. Deferoxamine treatment prevented these effects, while the usefulness of L-arginine remained doubtful.     

乐果亚长期暴露对大鼠肝脏氧化应激的影响

本试验旨在研究乐果(Dimethoate)对大鼠的毒性作用,探讨乐果中毒的氧化应激机制.将24只SD大鼠分成对照组和3个染毒组,分别以0、1、6、30 mg/kg体质量剂量灌服乐果,连续灌服30 d后,测定血浆和肝脏胆碱酯酶(ChE)活性及肝脏中超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)、过氧化氢酶(CAT)活性和丙二醛(MDA)含量,并观察肝脏组织学和超微结构变化.结果显示,乐果染毒后大鼠血浆和肝脏ChE活性均极显著降低(P<0.01);大鼠肝脏SOD活性呈上升趋势,而GSH-Px、CAT活性随染毒剂量增加呈先下降后上升趋势;各染毒组肝脏MDA含量均呈上升趋势;组织学和超微结构检查显示肝细胞脂肪变性、凋亡等.结果表明.大鼠乐果持续染毒可以诱导机体脂质过氧化增强,并导致肝脏结构损伤,说明氧化应激在乐果的肝脏毒性中发挥重要作用.