Poisoning of mice by Baccharis coridifolia: An experimental model

The poisonous plant Baccharis coridifotia causes necrosis in lymphoid tissues and the gastrointestinal tract of cattle, horses, sheep and rabbits. An experimental poisoning of mice was undertaken to establish an experimental model in a laboratory animal specie. A single 5 to 8-g/kg dose of a suspension of the plant was administered by gavage to II mice. To 3 other control mice, the same volume of water was administered. Plant-dosed mice manifested clinical effects after 12 h: tachipnea, trembles, dehydration and prostration. Most of the dosed mice died 14 to 33 h after plant administration-3 survived for 12 d. Six mice had remarkable necrosis of the germinative center of secondary follicles in lymph nodes and spleen; 3 mice had necrosis of lymphoid tissues in intestine and thymus. Mice reproduce most of the lesions observed in naturally poisoned cattle and the use of this specie as an experimental model is valid.

Comparative experimental infection of Lacazia loboi in BALB/c and B10.A mice

Both hind foot pads of BALB/c and B10.A mice strains, were inoculated with a fungal suspension of Lacazia loboi obtained from a Jorge Lobo's disease patient. The suspension had 9 × 105 cells/ml and its viability index was 45%. The animals were sacrificed at different time periods varying from 24 h to 18 months after inoculation. The BALB/c mice developed an extensive granulomatous infiltrate, similar to the disease in humans, that progressively evolved. The number of fungal elements also increased as the disease progressed, and after the seventh month of inoculation, macroscopic changes of the foot pads were evident. Although the B10.A mice developed an exuberant granulomatous infiltrate, macroscopic changes were not detected. The number of fungal cells in the infected tissues increased in number, but they were lower then the numbers found in the BALB/c strain. The viability indexes were also lower for the B10.A strain. Considering the histopathological findings, the presence of macroscopic changes and the great amount of fungal cells in the infected tissues, the authors concluded that the BALB/c mice strain was more susceptible to L. loboi infection than the B10.A strain.

Experimental peri-implant tissue breakdown around different dental implant surfaces: Clinical and radiographic evaluation in dogs

Purpose: Tissue reactions to 4 different implant surfaces were evaluated in regard to the development and progression of ligature-induced peri-implantitis. Materials and Methods: In 6 male mongrel dogs, a total of 36 dental implants with different surfaces (9 titanium plasma-sprayed, 9 hydroxyapatite-coated, 9 acid-etched, and 9 commercially pure titanium) were placed 3 months after mandibular premolar extraction. After 3 months with optimal plaque control, abutment connection was performed. Forty-five days later, cotton ligatures were placed around the implants to induce peri-implantitis. At baseline and 20, 40, and 60 days after placement, the presence of plaque, peri-implant mucosal redness, bleeding on probing, probing depth, clinical attachment loss, mobility, vertical bone loss, and horizontal bone loss were assessed. Results: The results did not show significant differences among the surfaces for any parameter during the study (P > .05). All surfaces were equally susceptible to ligature-induced peri-implantitis over time (P < .001). Correlation analysis revealed a statistically significant relationship between width of keratinized tissue and vertical bone loss (r 2 = 0.81; P = .014) and between mobility and vertical bone loss (r 2 = 0.66; P = .04), both for the titanium plasma-sprayed surface. Discussion and Conclusions: The present data suggest that all surfaces were equally susceptible to experimental peri-implantitis after a 60-day period.

Effect of Brazilian propolis on experimental hepatotoxicity in rats

Propolis (bee glue) is one of the major hive products of bees and is rich in flavonoids, which are known for their antioxidant activities. The aim of this study was to evaluate the hepatoprotective effects of the ethanolic extract of propolis (EEP) against experimental carbon tetrachloride (CCl 4)-induced liver toxicity in rats by means of biochemical indices. The animals were divided into 4 groups: GI= received mineral oil; GII= CCl 4(4mL/kg; Lp., single dose) treated; GIII= CCl4 (4mL/kg; i.p., single dose) treatment followed by ethanolic extract of propolis (100mg/kg) for gavage from the species Tetragonisca angustula, daily for 3 days and GIV= CCl4 (4mL/kg; i.p., single dose) treatment followed by ethanolic extract of propolis (100mg/kg) for gavage from the species Nannotrigonea testaceicornes, daily, for 3 days. The serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), cholesterol and triacylglycerols were estimated after 3 days. CCl 4 caused a maximum increase (p<0,01) above biochemical parameters. As compared to CCl4 group (GII), the EEP (GIII and GIV) showed reduction in cholesterol, triacylglycerol, ALT, AST and alkaline phosphatase activity in the serum. In conclusion, these data indicate that EEP improved the dyslipidaemia, moreover, significantly attenuated increases in serum ALT and AST activities in rats with liver damage induced by carbon tetrachloride.

Determination of acetonitrile and cyanide in rat blood: Application to an experimental study

Methods were developed for the analysis of acetonitrile and its metabolite cyanide in the blood of rats exposed to acetonitrile. Acetonitrile was analyzed by the headspace technique coupled to gas chromatography with detection by flame ionization, and cyanide was analyzed by high-performance liquid chromatography with fluorescence detection (λ ex = 418 nm and λ em = 460 nm) after derivatization of the ion with naphthalene 2,3-dicarboxyaldehyde and taurine. The quantitation limits of the methods for the analysis of acetonitrile and cyanide were 4.875 μg/mL and 0.025 μg/mL, respectively. The coefficients of variation of 10% or less obtained for intra- and interassay precision indicate the precision of these analytical methods and the systematic errors, all less than 5%, indicate that the methods are quite accurate. The methods were applied to an experimental study after the animals received acetonitrile at the doses of 2 mmol/kg or 5 mmol/kg.

Experimental candidosis and recovery of Candida albicans from the oral cavity of ovariectomized rats

The aim of this study was to analyze the development of candidosis and the recovery of C. albicans from the oral cavity of ovariectomized and sham-ovariectomized rats. One hundred aiid twenty-four rats originally negative for Candida spp. in the oral cavity were divided into two groups: ovariectomized and sham-ovariectomized. Fifty-eight ovariectomized and the same quantity of sham-ovariectomized rats were inoculated with C. albicans for the study of candidosis development and recovery of yeast. Four animals from each group were not inoculated with yeast suspension and were submitted to tongue dorsum morphologic analysis by optical and scanning electron microscopy. The development of candidosis in the tongue dorsum was observed by optical and scanning electron microscopy in the periods of 6 hr, 24 hr, 7 days and 15 days after the last inoculation. Recovery of C. albicans was performed by oral samples plating on Sabouraud agar after 1,2, 5 and 7 days and progressively at each 15-day interval until negative cultures for yeasts were obtained. The results were analyzed by Mann-Whitney and Student's t tests. The tongue dorsum of sham-ovariectomized and ovariectomized rats, not infected by Candida, presented normal aspect. Among the infected rats, the ovariectomized group showed less occurrence of candidosis lesions and lower recovery of C. albicans from the oral cavity in relation to the sham-ovariectomized group. It could be concluded that candidosis was less frequent from the oral cavities of ovariectomized rats in relation to sham-ovariectomized.

Intravenous versus nebulized ceftazidime in ventilated piglets with and without experimental bronchopneumonia: Comparative effects of helium and nitrogen

Background: Lung deposition of intravenous cephalosporins is low. The lung deposition of equivalent doses of ceftazidime administered either intravenously or by ultrasonic nebulization using either nitrogen-oxygen or helium-oxygen as the carrying gas of the aerosol was compared in ventilated piglets with and without experimental bronchopneumonia. Methods: Five piglets with noninfected lungs and 5 piglets with Pseudomonas aeruginosa experimental bronchopneumonia received 33 mg/kg ceftazidime intravenously. Ten piglets with noninfected lungs and 10 others with experimental P. aeruginosa bronchopneumonia received 50 mg/kg ceftazidime by ultrasonic nebulization. In each group, the ventilator was operated in half of the animals with a 65%/35% helium-oxygen or nitrogen-oxygen mixture. Animals were killed, and multiple lung specimens were sampled for measuring ceftazidime lung tissue concentrations by high-performance liquid chromatography. Results: As compared with intravenous administration, nebulization of ceftazidime significantly increased lung tissue concentrations (17 ± 13 vs. 383 ± 84 μg/g in noninfected piglets and 10 ± 3 vs. 129 ± 108 μg/g in piglets with experimental bronchopneumonia; P < 0.001). The use of a 65%/35% helium-oxygen mixture induced a 33% additional increase in lung tissue concentrations in noninfected piglets (576 ± 141 μg/g; P < 0.001) and no significant change in infected piglets (111 ± 104 μg/g). Conclusion: Nebulization of ceftazidime induced a 5- to 30-fold increase in lung tissue concentrations as compared with intravenous administration. Using a helium-oxygen mixture as the carrying gas of the aerosol induced a substantial additional increase in lung deposition in noninfected piglets but not in piglets with experimental bronchopneumonia. © 2005 American Society of Anesthesiologists, Inc. Lippincott Williams & Wilkins, Inc.

Water-soluble extract of Coleus barbatus modulates weight gain, energy utilization and lipid metabolism in secondary biliary cirrhosis: an experimental study in young rats.

PURPOSE: To test if a water extract of Coleus barbatus (WEB) has any effect on weight gain, food energy utilization and lipid metabolism in young rats with obstructive cholestasis. METHODS: Forty 21 day old (P21) Wistar rats, in groups of 10, were submitted to one of the following treatments: a sham operation with daily water or WEB administration, double ligature and resection of the bile duct with daily water or WEB administration. At P49 they were submitted for euthanasia when the following were determined: ingested feed (IF), energy utilization (EU) and weight gain (WG) from P29 to P49, together with total serum cholesterol (TC) and triacylglycerol (TG) concentrations, liver wet weight (LWW) and fat content (LFC). Two Way ANOVA and the S.N.K. test for paired comparisons were employed to study the effects of cholestasis and those of WEB and their interactions (p < or = 0.05). RESULTS: Cholestasis, independently of WEB, and WEB, independently of cholestasis both reduced IF, EU, and WG but there was no significant interaction between the two factors. Cholestasis, independently of WEB, increased LWW, LFC, the TC and TG The WEB, independently of cholestasis, reduced these values, and there was a significant interaction between the two factors; such that these effects were more accentuated in animals with cholestasis. CONCLUSION: The WEB reduced IF, WG, and EU, both in the presence and absence of cholestasis in the same proportion. It also partially inhibited the increase in LWW, LFC, TC and TG caused by cholestasis.

Methods of experimental induction of periapical inflammation. Microbiological and radiographic evaluation

Aim: To evaluate the influence of coronal filling and apical perforation on the induction of periapical inflammation. Methodology: Fifty-eight root canals in the teeth of dogs were divided into four groups. Groups I and II: root canals were exposed for 180 days; groups III and IV: root canals were exposed for 7 days and then the access cavity filled for 53 days. The root apices of groups I and III were perforated after the coronal opening, whilst those of groups II and IV remained intact. Standard radiographs were taken before and after the experimental periods. Digital images of the radiographs were created and then analysed by three examiners. After induction of periapical inflammation, the root canal contents were collected using paper points. Microbiologic evaluation of the type of microorganism was carried out by culture in different growth media. The radiographic and microbiologic data were statistically analysed using ANOVA at a 5% significance level. Results: There were a greater total number of microorganisms in groups I and II (P < 0.05). The number of anaerobes was greater than the number of aerobes (P < 0.05). The size of the periapical radiolucencies were not significantly different between the experimental groups. Conclusions: The different methods analysed induced similar areas of periapical radiolucency in dogs with predominantly anaerobic bacteria. However, the time required for induction was less when the method with coronal filling was used. © 2005 International Endodontic Journal.

β-carotene attenuates the paradoxical effect of tobacco smoke on the mortality of rats after experimental myocardial infarction

The objective of this study was to investigate the effects of exposure to tobacco smoke (ETS) in rats that were or were not supplemented with dietary β-carotene (BC), on ventricular remodeling and survival after myocardial infarction (Ml). Rats (n = 189) were allocated to 4 groups: the control group, n = 45; group BC administered 500 mg/kg diet, n = 49, BC supplemented rats; group ETS, n - 55, rats exposed to tobacco smoke; and group BC+ETS, n = 40. Wistar rats weighing 10O g were administered one of the treatments until they weighed 200 to 250 g (∼5 wk). The ETS rats were exposed to cigarette smoke for 30 min 4 times/d, in a chamber connected to a smoking device. After reaching a weight of 200-250 g, rats were subjected to experimental MI (coronary artery occlusion) and mortality rates were determined over the next 105 d. In addition, echocardiographic, isolated heart, morphometrical, and biochemical studies were performed. Mortality data were tested using Kaplan-Meyer curves and other data by 2-way ANOVA. Survival rates were greater in the ETS group (58.2%) than in the control (33.3%) (P = 0.001) and BC+ETS rats (30.0%) (P = 0.007). The groups did not differ in the other comparisons. Left ventricular end-diastolic diameter normalized to body weight was greater and maximal systolic pressures were lower in the ETS groups than in non-ETS groups. Previous exposure to tobacco smoke induced a process of cardiac remodeling after MI. There is a paradoxical protector effect with tobacco smoke exposure, characterized by lower mortality, which is offset by BC supplementation. © 2005 American Society for Nutritional Sciences.

Prostatic stromal microenvironment and experimental diabetes

The diabetes causes alterations in various organ systems, including the male accessory sex glands. The prostate is very important in the reproductive process and it is a frequent target of malignant changes. The aim of this work was to demonstrate the histochemical and ultrastructural alterations in the prostate of diabetic animals. Two groups of animals were utilized: control and non-obese diabetic mice (NOD). Twelve days after the characterization of diabetic status the ventral prostate was collected, fixed in Karnovsky and paraformaldehyde, processed for histochemistry and TEM associated to stereology. The results showed reduction of the epithelial area and increasing of the stromal area with muscular and collagen hypertrophy in the prostatic gland. It was characterized the development of prostatic intraepithelial neoplasia, inflammatory processes and dilation of the organelles involved in the secretory process. It was concluded that diabetes besides damaging the reproductive process, affects the glandular homeostasis favoring the development of prostatic pathologies. ©2005, European Journal of Histochemistry.

The number of podocyte and slit diaphragm is decreased in experimental diabetic nephropathy

Purpose: To determine the number of podocyte, slit diaphragms, slit diaphragm extensions and GBM thickness in diabetic nephropathy. Methods: Sixty Rattus Wistarof both sexes weighing 200-300g were divided in two experimental groups: normal group 10 animals, and alloxan diabetic rats - 50 animals. Alloxan was administered in a single IV dose of 42mg/kg body weight. Body weight, water and food intake, diuresis, and blood and urine glucose were determined in both groups before alloxan injection and two weeks, six and twelve months after alloxan injection. Proteinuria was measured at 12 months in both groups. After 12 months animals were sacrificed, and the right kidney processed for electron microscopy. Results: Clear clinical and laboratory signs of severe diabetes were seen, in all alloxan-diabetic rats at all follow-up times. Glomerular basement membrane (GBM) thickening, podocyte number, and slit diaphragm number and extension were determined. GBM of all diabetic rats was significantly thicker (median=0.29μm; semi-interquartile range=0.065μm) than in the normal rats (0.23μm; 0.035μm). Diabetic rat podocyte number (8; 1), slit diaphragm number (4; 1), and slit diaphragm extension (0.021μm; 0.00435μm) were significantly lower than in normal rats (11; 1) and (7; 1.5), and (0.031μm; 0.0058μm). Diabetic rat proteinuria (0.060mg/24h; 0.037mg/24h) was higher than in normal rats (0.00185mg/24h; 0.00055mg/24h). Conclusion: Experimental diabetes is associated with significant (p<0.05) changes in podocyte foot process, slit number, slit diaphragm extension, and GBM thickness.

Bone reformation and implant integration following maxillary sinus membrane elevation: An experimental study in primates

Background: Recent clinical studies have described maxillary sinus floor augmentation by simply elevating the maxillary sinus membrane without the use of adjunctive grafting materials. Purpose: This experimental study aimed at comparing the histologic outcomes of sinus membrane elevation and simultaneous placement of implants with and without adjunctive autogenous bone grafts. The purpose was also to investigate the role played by the implant surface in osseointegration under such circumstances. Materials and Methods: Four tufted capuchin primates had all upper premolars and the first molar extracted bilaterally. Four months later, the animals underwent maxillary sinus membrane elevation surgery using a replaceable bone window technique. The schneiderian membrane was kept elevated by insertion of two implants (turned and oxidized, Brånemark System®, Nobel Biocare AB, Göteborg, Sweden) in both sinuses. The right sinus was left with no additional treatment, whereas the left sinus was filled with autogenous bone graft. Implant stability was assessed through resonance frequency analysis (Osstell™, Integration Diagnostics AB, Göteborg, Sweden) at installation and at sacrifice. The pattern of bone formation in the experimental sites and related to the different implant surfaces was investigated using fluorochromes. The animals were sacrificed 6 months after the maxillary sinus floor augmentation procedure for histology and histomorphometry (bone-implant contact, bone area in threads, and bone area in rectangle). Results: The results showed no differences between membrane-elevated and grafted sites regarding implant stability, bone-implant contacts, and bone area within and outside implant threads. The oxidized implants exhibited improved integration compared with turned ones as higher values of bone-implant contact and bone area within threads were observed. Conclusions: The amount of augmented bone tissue in the maxillary sinus after sinus membrane elevation with or without adjunctive autogenous bone grafts does not differ after 6 months of healing. New bone is frequently deposited in contact with the schneiderian membrane in coagulum-alone sites, indicating the osteoinductive potential of the membrane. Oxidized implants show a stronger bone tissue response than turned implants in sinus floor augmentation procedures. © 2006 Blackwell Publishing, Inc.

Variabilidade clínica na determinação da dose tóxica oral em intoxicação experimental por fluoroacetato de sódio em gatos

The sodium monofluoroacetate (FAC) or compound 1080 is a potent rodenticide used for a rodents and vertebrate pest control. It was prohibited in many countries because of its high toxicity, but in Brazil exist evidences of ilegal use causing the intoxication in children and domestic animals. The fluoroacetate metabolite, fluorocitric acid, blocks body energy production by inhibit the Krebs cycle, resulting in neurological and cardiacs signs. In the present study, four group of oral toxic dosis of the FAC were compared in cats. The best oral toxic dose for clinical signs presentation, without cause acute lethality, was 0,45mg/kg. The clinical variability was dosis dependent and its intensity, in crescent order, was: light signs (dose 1: 0,3mg/kg), light to moderate (dose 2: 0,4mg/kg), moderate to severe (dose 3: 0,45mg/ kg) and severe (dose 4: 0,5mg/kg). There was individual clinical variability between animals that received the same oral toxic dose.

Determinação de desmineralização óssea em gatos após tirotoxicose experimental

Hyperthyroidism can result in serious effects on the bone metabolism in humans as well as animals. For a better characterization of thyrotoxicosis effects, 16 cats were induced into thyrotoxicosis by intaking a dose of 150 μg/kg of sodium L-thyroxine every 24 hours during 42 days. The hormonal levels were evaluated by radioimmunoassay technique and the bone mineral density of the right distal radius extremity was measured through the radiographic optical densitometry. Was verified significant bone demineralization seven days of hormonal intake as weel as radius demineralization.