Correlation between B-cell mitogenicity and immunosuppressor effects of a protein released by porcine monocytes infected with African swine fever virus

Virus-free supernatants of cultured swine monocytes infected by African swine fever virus (ASFV) suppressed in vitro proliferation of porcine and human blood mononuclear cells in response to phytohemagglutinin and the in vivo primary immune response of C57BL/6 mice against sheep RBC. The supernatants were fractionated by discontinuous ion-exchange chromatography and subfractionated by double-step preparative isoelectric focusing. The pool of the most purified active subfractions (F5'EP-ASFV) is made up of heat-unstable material, can be stained by silver nitrate, and has an isoelectric point of 3.88, a maximal optical density at 280 nm, and a mass of 36,000 daltons. In vivo kinetic studies in nonimmunized C57BL/6 mice were performed on days 1, 2, 3, 5, and 7 after injection with 50 micrograms of F5'EP-ASFV protein. Compared with the untreated mice, the treated mice had a noticeable increase in nonspecific immunoglobulin-secreting splenic plaque-forming cells (PFC) with the following isotype profile: IgG2a greater than IgG2b greater than IgG3 greater than IgG1 congruent to IgM. Three days after treatment with the active material, specific IgM PFC against sheep RBC increased up to 23-fold. In C57BL/6 mice immunized against sheep RBC 2 days after treatment with F5'EP-ASFV, the increase in nonspecific PFC was followed by a suppression of specific PFC response in the respective isotype. When C57BL/6 mice were treated after priming with sheep RBC, however, there was little or no suppression of specific PFC and the increase in nonspecific PFC was considerably lower than that in the other F5'EP-ASFV-treated mice. In this case, kinetic curves of specific vs nonspecific PFC of each isotype were mirror images. Mice treated with 200 micrograms of F5'EP-ASFV protein died with hemorrhagic diastasis.     

Evaluation of the prophylactic effect and curative efficacy of fipronil 1% pour on (Topline) on post-castration scrotal myiasis caused by Cochliomyia hominivorax in cattle

A field trial was carried out during a summer-fall period on a commercial beef cattle farm in Minas Gerais State, located in the Southeast of Brazil. In order to evaluate the prophylactic effect and the curative efficacy of fipronil in a 1% solution, 200 Zebu crossbred bulls, with ages varying from 20 to 30 months and weights from 233 to 362 kg, were selected. The bulls were assigned by ranked pair to an untreated control group (A) or to a treated group (B), resulting in 100 animals per group. All experimental animals were surgically castrated on day 0, following routine procedures. After castration all animals in the group B were treated with 10 mg/kg bw of a 1% fipronil solution, topically on the dorsal mid-line. The wounds were individually inspected on days: 2, 4, 7, 10, 14, 17, 21, 28 and 35. After castration the animals were naturally exposed to Cochliomyia hominivorax and remained in the same pasture throughout the trial. Among the animals in the control group, 83 were observed to harbor C. hominivorax eggs, with a total of 97 ovipositions, and among those 73 animals had active myiasis. In group B (fipronil 1%), 66 animals showed C. hominivorax eggs, with 92 ovipositions and five animals with active myiasis. Most ovipositions and active myiasis were detected until seven days post-castration for both groups. Wound parasite infestation evidenced bleeding, serous purulent exudation and presence of active C. hominivorax larvae. Treatment with fipronil 1% had a prophylactic effect on scrotal wounds against the development of C. hominivorax larvae in more than 95% of the treated animals for up to 17 days after castration. The treatment showed partial protection of 66% and 50% on days 21 and 28 post-treatment (pt), respectively. Three animals from the control group and one from the treated group showed active screwworms on day 21 pt, and one animal from the treated group and two from the control group also presented C. hominivorax larvae on scrotal wounds on day 28 pt. By the end of the observation period (day 35 pt), the castration wound had healed in all animals. All experimental animals presenting scrotal wounds infested with C. hominivorax larvae were treated with a 1% pour-on formulation of fipronil, on the same day that infestation was observed. Active C. hominivorax larvae were not seen during the monitoring period immediately after treatment. The curative efficacy of fipronil 1% against C. hominivorax larvae infestation in castration wounds was 100%.     

Variation in population density of horn flies (Haematobia irritans irritans) (L.) (Diptera: Muscidae) in Nellore cattle (Bos indicus)

The population density of horn flies was evaluated in the year 1998 in the municipality of Ara?atuba, S?o Paulo Brazil, in relation to temperature and rainfall conditions. Two lots of 30 Nellore steers (Bos indicus) were used which had no insecticidal treatment and were naturally infested with horn flies. The infestations were assessed by two counting methods, i.e., the traditional estimate method and the filming method. The highest fly frequencies were recorded in spring, summer, autumn and the lowest frequencies were recorded in winter. The increase in fly number was positively correlated (P<0.05) with rainfall.     

Structure and ultrastructure of the celiac-mesenteric ganglion complex in the domestic dog (Canis familiaris)

A number of neurons of the autonomic nervous system are situated in the ganglia and can be systematically divided into pre-vertebrals, paravertebrals, intramural and para-viscerals. The celiac-mesenteric ganglion, an important pre-vertebral ganglion, is located together with the abdominal aorta and links the central nervous system to the peripheral system, participating in the coordination of peripheral reflexes and principally innervating the stomach, intestines, accessory glands (liver and pancreas). In addition, the celiac-mesenteric ganglion also contributes to the innervation of the spleen and has a role in gastrointestinal motility control. This study examined the structural and ultrastructural aspects of 40 celiac-mesenteric ganglia from domestic dogs. For light microscopy ganglia were included in paraplast and stained with haematoxylin-eosin, picrosirius, toluidine blue, Calleja's and Masson's trichrome. For examination by electron microscopy, the ganglia were submitted to cryofracture, enzyme digestion, hydrolysis and fixed in 5% glutaraldehyde in 0.1 M phosphate buffer (pH 7.4). The celiac-mesenteric ganglion was observed as a ganglionic complex composed of various ganglionic units separated by types I and III collagen fibres, predominantly unmyelinated nerve fibres and continuous capillaries. This complex is surrounded by a double-layer capsule (internal and external). The principal ganglion cells had eccentric nuclei with two nucleoli, the nucleolemma was double and presented nuclear pores. In the cytoplasm there were vesicles of the Golgi apparatus, electron-dense vacuoles, mitochondrias, smooth and granulated endoplasmic reticulum and free ribosomes. In conclusion, this ganglionic complex, in contrast to similar structures in the enteric nervous system, presents separate ganglionic units in a systematic arrangement related to the extrinsic and specific innervation of the target organs.     

Development of an ELISA system for detection of anti-Anaplasma marginale antibodies in cattle in Brazil

An ELISA test was developed for detecting antibodies against Anaplasma marginale in bovine sera. Four antigenic preparations were produced from infected red blood cells. Some aliquots of this preparation were stored at -70 degrees C with 30% DMSO in phosphate-buffered saline (PBS) and others were lysed with 0.9% NH4Cl and stored at -20 degrees C. Typical anaplasmal structures were seen by electron microscopy in the antigenic preparations containing the erythrocytes that had been stored with DMSO. The performance of the ELISA test was evaluated by testing 298 positive serum samples collected from immunized cattle, 39 negative serum samples collected from cattle imported from areas free of A. marginale and 50 samples collected from cattle naturally infected in the field. The test gave a specificity of 94.87% and a sensitivity of 100%.     

Prolonged anesthesia with desflurane and fentanyl in dogs during conventional and laparoscopic surgery

OBJECTIVE: To determine the effects of prolonged anesthesia with desflurane in dogs undergoing laparotomy or abdominal laparoscopy. DESIGN: Randomized prospective study. ANIMALS: 20 adult mixed-breed dogs. PROCEDURE: Dogs were randomly assigned to 1 of 2 groups with 10 dogs/group. Anesthesia was induced with propofol and maintained with desflurane and fentanyl, and pyloroplasty was performed. In 10 dogs, a ventral midline laparotomy was performed; in the other 10, abdominal laparoscopy was performed. Dogs were monitored for cardiovascular and respiratory responses (ECG, oxygen saturation [SpO2], arterial blood pressure, rectal temperature, end-tidal partial pressure of carbon dioxide [PETCO2], and expired desflurane concentration). Recovery times were recorded. RESULTS: Mean +/- SD duration of anesthesia was 201 +/- 25 minutes for dogs undergoing laparotomy and 287 +/- 15 minutes for dogs undergoing laparoscopy. Anesthesia was accompanied by hypotension that was less severe in dogs undergoing laparoscopy. Heart rate did not vary significantly during anesthesia. The SpO2 was > 97% in all dogs at all times, and PETCO2 remained within reference limits. Recovery times for dogs that underwent laparotomy were not significantly different from those for dogs that underwent laparoscopy. Mean +/- SD time to standing was 13.6 +/- 2.4 minutes for dogs that underwent laparotomy and 12.5 +/- 2.9 minutes for dogs that underwent laparoscopy. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that induction of anesthesia with propofol and maintenance with desflurane and fentanyl is safe in dogs undergoing abdominal surgery.     

Stratigraphy of near-valley head quaternary deposits and evidence of climate-driven slope-channel processes in southern Brazilian highlands

During the past 40 years colluvial and alluvial deposits have been used in Brazil as good indicators of regional landscape sensitivity to Quaternary environmental changes. In spite of the low resolution of most of the continental sedimentary record, geomorphology and sedimentology may favor palaeoenvironmental interpretation when supported by independent proxy data. This paper presents results obtained from pedostratigraphic sequences, in near-valley head sites of southern Brazilian highlands, based on geomorphologic, sedimentologic, micromorphologic, isotopic and palynologic data. Results point to environmental changes, with ages that coincide with Marine Isotopic Stages (MIS) 5b; 3; 2 and 1. During the late Pleistocene, although under temperatures and precipitation lower than today, the local record points to relatively wet local environments, where shallow soil-water saturated zones contributed to erosion and sedimentation during periods of climatic change, as during the transition between MIS 2 and MIS 1. Late Pleistocene events with ages that coincide with the Northern Hemisphere Younger Dryas are also depicted. During the mid Holocene, slope-wash deposits suggest a climate drier than today, probably under the influence of seasonally contrasted precipitation regimes. The predominance of overland flow-related sedimentary deposits suggests an excess of precipitation over evaporation that influenced local palaeohydrology. This environmental condition seems to be recurrent and explains how slope morphology had influenced pedogenesis and sedimentation in the study area. Due to relative sensitiveness, resilience and short source-to-sink sedimentary pathways, near-valley head sites deserve further attention in Quaternary studies in the humid tropics.