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.     

The histopathogenesis of paralytic rabies in six-week-old C57BL/6J mice following inoculation of the CVS-11 strain into the right triceps surae muscle

A fatal encephalomyelitis was developed after intracerebral and hind limb inoculation of in 6-week-old C57BL/6J mice by the inoculation of fixed rabies virus (CVS-11 strain), intracerebrally and into hind. After the intracerebral inoculation, virus antigens were detected in the cerebral cortex and hippocampus at 2 days postinoculation (PI), and later spread centrifugally to thalamus, brain stem, cerebellum, spinal cord and spinal ganglia. At 4 days PI, severe apoptosis and DNA fragmentation were observed in the hippocampus and cerebral cortex. All mice infected intracerebrally were dead without limb paralysis at from 10 to 11 days PI. In contrast, mice infected with virus intramuscularly were persistently observed virus antigens in the myocytes at the site of inoculation from 2 days PI. At 4 days PI, the antigens were demonstrated in the spinal dorsal root ganglia, spinal cord and muscle spindles without their detection in the cerebrum and hippocampus. There were no apoptosis in the spinal cord and dorsal root ganglia, however hind limb paralysis was found in all infected mice. Hind limb paralysis was progressed to quadriparalysis, and mice were dead from 11 to 13 days PI. From 4 days PI, necrosis of neuron was observed in the the spinal and dorsal ganglia with infiltration of lymphocyte. This study suggested that the necrosis of spinal neurons was more important to cause the paralysis of hind limb rather than the severe cerebral infection and apoptosis in C57BL/6J mice infected with CVS-11 strain. The virus primarily replicated in the muscles was ascended the spinal cord via afferent fibers and retrogradely invaded the cerebrum, and with subsequent spread to muscle spindles.     

Evaluation of the card agglutination test (CATT/T. evansi) for detection of Trypanosoma evansi infection in water buffaloes (Bubalus bubalis) in Egypt

A card agglutination test (CATT/T. evansi) was evaluated for detection of antibodies against Trypanosoma evansi (T. evansi) in experimentally and naturally infected buffaloes. Four calves were inoculated with a strain of T. evansi isolated from a dromedary camel. Parasitological examination of the calves revealed trypanosomes in the blood from days 4 to 9 post-inoculation (PI). General emaciation appeared from day 26 PI and aggravated until the end of the experiment (day 88 PI). Antibodies against T. evansi were detectable from day 8 PI till the end of the experiment. Parasitological examination of 200 water buffalo blood samples obtained from slaughterhouses revealed negative results. Serological examination of these animals showed that 48 (24%) water buffaloes had anti-T. evansi antibodies.     

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.     

Elemental composition, water, and total lipid content in peripheral nerves, spinal cord and brain of healthy adult dogs

Peripheral nerves, spinal cord, and brain of healthy adult dogs were analysed biochemically for sodium, potassium, calcium, magnesium, copper, zinc, iron, aluminium, silicon, total chloride, total tissue water and total lipid content. Flame atomic absorption spectrophotometry was used for elemental quantitation of the hydrochloric acid tissue extracts. Cerebrum and spinal cord had similar values for all parameters measured. Total sodium values were higher in nerves compared to central nervous system (CNS) (brain and spinal cord), while respective values for potassium were lower. Tissue levels of calcium, iron and silicon were comparable in brain, spinal cord and nerves. However, magnesium concentrations were two to three times higher in CNS than in nerves; and the reverse was true for aluminium levels. Tissue concentrations of zinc and copper were marginally higher in CNS than in nerves.     

MAGNETIC RESONANCE IMAGING OF THE BRAIN AND COELOMIC CAVITY OF THE DOMESTIC PIGEON (Columba livia domestica)

The technical feasibility of performing magnetic resonance imaging (MRI) in domestic pigeons was investigated. Imaging was performed with a 1.5 Tesla magnet using a human knee surface coil. The head and coelomic cavity of isoflurane-anesthetized birds were imaged in the dorsal, sagittal, and transverse planes to produce T1-weighted, T2-weighted, and contrast-enhanced T1-weighted images. The birds were then euthanatized, formalin perfused, frozen, and sectioned in the corresponding anatomic planes. The anatomy defined by MRI was correlated with gross anatomic sections made from the same birds. The following CNS structures were identified: cerebral hemispheres, cerebellum, optic chiasm, optic lobes, brain stem, and cranial spinal cord. The cornea, lens, and vitreous were also well differentiated in dorsal section MRI's. The abdominal organs identified included proventriculus, ventriculus, intestines, cloaca, liver, kidneys, spleen, testes, and ovary. The hepatic and renal vasculature were well defined.     

Development of a TaqMan PCR assay for the detection of Trypanosoma evansi, the agent of surra

A TaqMan PCR assay was developed for the detection of Trypanosoma evansi. The assay targets the internal transcribed spacer 1 (ITS-1) region of rRNA. The ITS-1 region of eleven strains of T. evansi from widely separated geographical regions were sequenced and alignments compared. Primers and probe for the test were designed from these sequence data. The assay was tested using blood from infected rats and was found to be sensitive, detecting less than one genomic equivalent of T. evansi. The assay has been tested against 10 different species of trypanosomes found in native animals in Australia and did not detect any of these trypanosome species. Time course experiments using rats infected with T. evansi were performed to compare the TaqMan assay with the Haematocrit centrifugation test (HCT) and the mouse inoculation (MI) assay. The assay was more sensitive than the HCT but not as sensitive as the MI. The TaqMan assay has the ability to rapidly detect T. evansi and determine the number of organisms present in a blood sample from an infected animal. This is the first time a TaqMan assay has been developed for the detection of T. evansi.     

Susceptibility of Trypanosoma evansi to propolis extract in vitro and in experimentally infected rats

Current therapy of Trypanosoma evansi infections is not effective for the vast majority of animals with relapsing parasitemia and clinical signs. Recently, attention is being focused on the antiparasitic activity of propolis. This study evaluated the susceptibility of T. evansi to propolis extract in vitro and in vivo. A dose-dependent trypanocidal activity of propolis extract was observed in vitro. All trypomastigotes were killed 1h after incubation with 10μgmL(-1) of the extract. In vivo, the concentrations of 100, 200, 300 and 400mgkg(-1) administered orally for 10 consecutive days showed no curative effect, and the rats died from the disease. However, rats treated with the two highest concentrations of propolis extract showed higher longevity than the other groups. Based on these data, we concluded that T. evansi is susceptible to propolis in vitro. Despite the lack of curative efficacy observed in vivo at the concentrations tested, the propolis extract can prolong life in rats infected with the protozoan.     

An immunohistochemical and ultrastructural study on age-related astrocytic gliosis in the central nervous system of dogs.

The pattern of astrocytic gliosis (AG) was examined in 2-month-old to 18-year-old dogs using glial fibrillary acidic protein (GFAP) immunohistochemistry and electron microscopy. Coronal sections from various levels of the central nervous system (CNS) were stained with hematoxylin & eosin, Luxol Fast Blue, Nissl, and Bodian in addition to GFAP. A consistent pattern of age-related AG was observed in the dogs. The white matter, cortico-medullary junction, and subcortical nuclei in the cerebrum, central nuclei in the cerebellum, various nuclei in the brain stem, and grey matter of the spinal cord showed even and intense GFAP staining. AG was also prominent in the cerebral and cerebellar cortices and thalamus. Moderate AG was observed in the hippocampus and white matter of the cerebellum and spinal cord. Electron microscopy demonstrated increased number of profiles of degenerative neural components in the vicinity of hypertrophic astrocytes in the cerebral cortex of the aged dogs. Moderate to severe AG was consistently shown in the CNS of the aged dogs. In contrast, young normal dogs showed minimum amounts of GFAP-positive astrocytes in the CNS. These findings suggest that the observed AG in the CNS of the dogs is a morphological expression of aging.     

Evaluation of beef tallow as a natural source of conjugated linoleic acid

Cis‐9, trans‐11 conjugated linoleic acid (9c, 11t CLA) is a potential anticarcinogen that is found in higher concentrations in beef lipids. However, the effect of CLA on lipid peroxidation, which is closely related to carcinogenesis, is controversial. In this study, we determined the levels of 9c, 11t CLA contents and thiobarbituric acid reactive substances (TBARS) in the tissues of rats fed beef lipid. Sprague‐Dawley rats (male, 8 weeks old) were fed experimental diets containing 20% lyophilized beef, and 12% beef tallow or vegetable oils, for 56 days. With the exception of the brain, the tissues from the rats fed the experimental diets accumulated 9c, 11t CLA, depending on the levels of CLA in the diets. The beef tallow group showed significantly higher 9c, 11t CLA contents in all tissues examined than the other diet groups. The intake of beef lipid did not affect the TBARS levels in the rat tissues. The hepatic lipid content from the beef tallow group was lower than that from the group fed vegetable oils. These results suggest that beef is a good source of 9c, 11t CLA, and that the intake of an appropriate level of beef lipid is not hazardous to health.     

Influence of Trypanosoma evansi in blood, plasma, and brain cholinesterase of experimentally infected cats

Changes in blood, plasma and brain cholinesterase activities in Trypanosoma evansi-infected cats were investigated. Seven animals were infected with 10⁸ trypomastigote forms each and six were used as control. Animals were monitored for 56 days by examining daily blood smears. Blood samples were collected at days 28 and 56 post-inoculation to determine the activity of acetylcholinesterase (AChE) in blood and the activity of butyrylcholinesterase (BChE) in plasma. AChE was also evaluated in total brain. The activity of AChE in blood and brain, and the activity of BChE in plasma significantly reduced in the infected cats. Therefore, the infection by T. evansi influenced cholinesterases of felines indicating changes in the responses of the cholinergic system.     

The expression of RoTat 1.2 variable surface glycoprotein (VSG) in Trypanosoma evansi and T. equiperdum

In order to define whether the variable antigenic type RoTat 1.2 is restricted to Trypansoma evansi and could be used as antigen in serological tests to differentiate T. evansi from Trypansoma equiperdum, the appearance of RoTat 1.2-specific antibodies in rabbits, experimentally infected with T. evansi and T. equiperdum, respectively, was analyzed. Ten strains of T. evansi and 11 strains of T. equiperdum originating from Asia, Europe, Africa and Latin America were tested. Rabbit pre-infection sera and sera of days 7, 14, 25, 35 post-infection (p.i.) were analyzed for the presence of antibodies reactive with RoTat 1.2 in immune trypanolysis, ELISA/T. evansi and CATT/T. evansi. Within the duration of the infection (maximum 35 days), all T. evansi as well as 9 out of 11 T. equiperdum infected rabbits became positive in all these tests. The rabbits infected with T. equiperdum OVI (South Africa) and BoTat 1.1 (Morocco) remained negative in the immune trypanolysis test although the latter rabbit became positive in the CATT/T. evansi and ELISA/T. evansi. On the contrary, both rabbits were positive in immune trypanolysis when tested against their respective infecting population. From these data, we conclude that most T. equiperdum strains express isoVATs of RoTat 1.2. This explains, in part, why antibody tests based on T. evansi RoTat 1.2 cannot reliably distinguish between infections caused by T. evansi and those caused by T. equiperdum unless it can be proven that most described T. equiperdum are actually misclassified T. evansi.     

Effects of an extract of Gingko biloba on bromethalin-induced cerebral lipid peroxidation and edema in rats.

The effects of administration of a commercially available extract of Gingko biloba (EGB) on bromethalin-induced brain lipid peroxidation and cerebral edema in adult male Sprague-Dawley rats was determined. Gingko biloba extract was given (100 mg/kg) by gavage immediately after bromethalin (1.0 mg/kg) administration. Rats were euthanatized at 24 hours after dosing. Brain lipid peroxidation was determined by measurement of brain malonaldehyde-thiobarbituric acid chromophore (MDA-TBA) concentration, brain sodium concentration, and brain water content. Treatment of bromethalin-dosed rats (10/group) with EGB was associated with a statistically significant (P less than 0.05) decrease in clinical sign severity, compared with bromethalin-dosed saline solution-treated rats. All rats given bromethalin and saline solution developed clinical signs of toxicosis including CNS depression, hind limb weakness, ataxia, paralysis, and coma. Some rats given bromethalin and EGB developed clinical signs, however, none developed hind limb paralysis. The brain MDA-TBA concentration (2.4 +/- 0.5 delta MDA-TBA concentration/mg of protein), percentage of water in brain tissue (80.3 +/- 0.30%), and brain sodium concentration (6.68 +/- 0.21 mg/g of dry weight) were significantly increased in rats given bromethalin and saline solution, compared with control rats given saline solution (1.0 +/- 0.1 delta MDA-TBA concentration/mg of protein; 78.1 +/- 0.33% water in brain tissue; 4.83 +/- 0.30 mg of brain Na+/g of dry weight) and rats given bromethalin and EGB (1.6 +/- 0.2 delta MDA-TBA concentration/mg of protein; 79.3 +/- 0.31% water in brain tissue; 5.37 +/- 0.34 mg of brain Na+/g of dry weight).(ABSTRACT TRUNCATED AT 250 WORDS)     

Presynaptic stimulation of dopaminergic CNS structures in sheep as a mechanism of immobilising action of Immobyl (fentanyl + azaperone)

The immobilising action of Immobyl (fentanyl : azaperone, 5:1) in six sheep has been analysed on the basis of the changes in dopamine, noradrenalin, adrenalin, homovanillic acid and 5-hydroxytryptamine concentrations in the corpus striatum, frontal motor cortex, pons, cerebellum and lumbosacral spinal cord as compared to the control animals which were given saline. Forty minutes after intramuscular injection of an immobilising dose (0.19 mg [kg bodyweight]-1), Immobyl caused a significant decrease in dopamine, noradrenalin and 5-hydroxytryptamine concentrations and a similarly large decrease in homovanillic acid concentration (47 per cent) in the corpus striatum with a simultaneous but insignificant increase in the concentrations of these substances in the frontal motor cortex region. In Immobyl immobilisation, sheep showed a significant increase in dopamine concentration with an equally significant decrease in homovanillic acid concentrations in the lumbosacral part of the spinal cord. It is suggested that fentanyl stimulates the presynaptic dopamine receptors in the corpus striatum in sheep, significantly decreasing synthesis and release of dopamine and noradrenalin and intensifying an inhibitory effect of the corpus striatum on locomotor activity and thus causes the immobilisation of the animal.     

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.     

Gliomatosis cerebri in two dogs

A 3.5 yr old Saint Bernard was evaluated for nonambulatory tetraparesis and cranial nerve dysfunction, and a 7 yr old rottweiler was evaluated for progressive paraparesis. Clinical signs of left-sided vestibular and general proprioceptive ataxia and cranial nerve VII dysfunction in the Saint Bernard suggested a lesion affecting the brain stem. Signs in the rottweiler consisted of general proprioceptive/upper motor neuron paraparesis, suggesting a lesion involving the third thoracic (T3) to third lumbar (L3) spinal cord segments. MRI was normal in the Saint Bernard, but an intra-axial lesion involving the T13-L2 spinal cord segments was observed in the rottweiler. In both dogs, the central nervous system (CNS) contained neoplastic cells with features consistent with gliomatosis cerebri (GC). In the Saint Bernard, neoplastic cells were present in the medulla oblongata and cranial cervical spinal cord. In the rottweiler, neoplastic cells were only present in the spinal cord. Immunohistochemistry disclosed two distinct patterns of CD18, nestin, and vimentin staining. GC is a rarely reported tumor of the CNS. Although GC typically involves the cerebrum, clinical signs in these two dogs reflected caudal brainstem and spinal cord involvement.     

Study on the antioxidant status of rats experimentally infected with Trypanosoma evansi

The antioxidant status of rats experimentally infected with Trypanosoma evansi isolated from a camel was studied using established parasitological, haematological and biochemical methods. The results indicated that infections in all rats resulted in a fulminating parasitaemia. Changes in blood parameters in T. evansi-infected rats indicated leukocytosis and a macrocytic hypochromic anaemia. A degree of anisocytosis was also observed. The activities of plasma glucose-6-phosphate dehydrogenase and glutathione peroxidase in whole blood of infected rats were significantly higher (p<0.05 and p<0.001, respectively) compared with control. No statistically significant difference was observed in the activity of superoxide dismutase in infected and control rats. Results obtained indicated that trypanosomosis caused oxidative stress and induced antioxidant enzymes.     

Effects of porcine brain hydrolysate on impairment of cognitive learning ability in amyloid β(1–40)‐infused rats

This study assessed whether administering porcine brain hydrolysate (PBH) ameliorates the impairment of spatial cognition learning ability in amyloid β (Aβ)‐infused rats. PBH was prepared using organic solvents (i.e., acetone and ethanol). Enzyme hydrolysates were derived from these PBH and the sequence of the Aβ peptide for infusion was selected. The results indicated the PBH, in particular EP (porcine brain extract with ethanol and protease N), demonstrated the potentials to reduce damage of neurodegenerative disorders in vitro and in vivo. The principal findings of this study indicate that PBH has prolyl endopeptidase inhibitory activity in vitro. Moreover, administering EP to Aβ(1–40)‐infused rats significantly improves their performance on reference, spatial performance, and working memory tests during water maze tasks; concurrent proportional decreases are also observed in malondialdehyde levels, acetylcholinesterase (AChE) activity, and Aβ accumulation levels in brain tissues. The PBH was suggested to ameliorate learning deficits associated with Alzheimer's disease by inhibition of lipid peroxidation in the brain of Aβ infused rat.     

A comparative evaluation of parasitological tests and a PCR for Trypanosoma evansi diagnosis in experimentally infected water buffaloes

In this study five parasitological methods and a polymerase chain reaction (PCR) were compared for the diagnostic sensitivity for Trypanosoma evansi in experimentally infected water buffaloes over a period of 15 weeks. The combined estimates of sensitivity (CE(se)) of the PCR proved to be highest at 78.2%, closely followed by the mouse inoculation (MI), the micro-haematocrite centrifugation technique (MHCT) and the mini-anion-exchange centrifugation technique (MAECT) with CE(se) of, respectively, 74.0, 69.6 and 62.4%. The CE(se) of the buffy-coat technique (BCT) at 38.6% and the sodium dodecyl sulfate (SDS) clarification technique at 25.1% were considerably lower. PCR detected consistently all buffaloes infected from week 3 post-infection (PI) onwards. For MI this occurred after 5 weeks PI while for MHCT and MAECT these sustainable high levels were reached in the 7th week PI. BCT and SDS never detected all buffaloes infected. The influence of time and temperature on the viability of T. evansi in heparinized blood from water buffalo was also studied. In general we observed that the survival time tends to be longer when blood is kept at 4 degrees C. In samples kept in direct sunlight parasites became undetectable with the MHCT after 30min. After treatment of the water buffaloes with diminazene aceturate, the PCR signal disappeared within 24h.     

The role of wild rodents in the transmission of Trypanosoma evansi infection in an endemic area of the Canary Islands (Spain)

Trypanosoma evansi was diagnosed for the first time in camels in the Canary Islands in 1997. Several sanitary measures including treatment of infected animals were taken; however, nowadays a little area is still infected. In order to determine possible reservoirs 138 wild rodents were trapped, 64 of them in the infected farms and the remaining 74 in other areas. The captured species were Rattus rattus (24), Rattus norvegicus (69) and Mus musculus domesticus (45). Serological (CATT/T. evansi), parasitological (micro-Hematocrit Centrifugation technique and stained smears) and molecular (PCR) methods for T. evansi and T. lewisi were used as diagnostic methods. None of the examined rodents was positive for T. evansi; 18, however, showed motile trypanosomes at micro-Hematocrit Centrifugation technique and resulted positive for T. lewisi by PCR. The results would suggest that the studied rodent species would not play a relevant role in the epidemiology of T. evansi infection in Canaries.