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Biomedical subjects

E A Bambirra

Publications and source records attributed to E A Bambirra.

At least 19 recordsLinked to original sources
PubMed1999

Evaluation of microbial infiltration in restored cavities--an alternative method.

This work evaluated the efficacy of an improved method used to determine the frequency of bacterial infiltration and bacterial population levels and morphotypes in cavities restored with adhesive composites in conventional mice. By using the alternative methodology suggested in this work, bacteria from microleakage were recovered and identified in cavities subjected to restoration procedures that used acid etching of the dentin and dentin adhesives used with light-curing resin. The methodology presented herein seems to be more effective than the one normally used to investigate the presence of bacteria, which uses acid demineralization of dental structures for the histological processing of tissues. The results suggest that the methodology presented in this work made it possible to recover and identify Gram-negative and Gram-positive bacteria from microleakage. Frequencies of microleakage and bacterial population levels in restored cavities using two different adhesive systems were not statistically different (p < 0.05).

Animals↗
PubMed1999

Protective effect of bifidus milk on the experimental infection with Salmonella enteritidis subsp. typhimurium in conventional and gnotobiotic mice.

The ability of Bifidobacterium bifidum from a commercial bifidus milk to antagonize Salmonella enteritidis subsp. typhimurium in vivo, and to reduce the pathological consequences for the host, was determined using conventional and gnotobiotic mice. Conventional animals received daily, by gavage, 0.1 ml bifidus milk containing about 10(9) cfu B. bifidum and germ-free animals received a single 0.1 ml dose. The conventional and gnotobiotic groups were challenged orally with 10(2) cfu of the pathogenic bacteria 5 and/or 10 d after the beginning of treatment. Control groups were treated with milk. Bifidus milk protected both animal models against the challenge with the pathogenic bacteria, as demonstrated by survival and histopathological data. However, to obtain the protective effect in gnotobiotic animals, the treatment had to be initiated 10 d before the challenge. In experimental and control gnotobiotic mice, Salm. enteritidis subsp. typhimurium became similarly established at levels ranging from 10(8) to 10(9) viable cells g-1 of faeces and remained at these high levels until the animals died or were sacrificed. It was concluded that the protection against Salm. enteritidis subsp. typhimurium observed in conventional and gnotobiotic mice treated with bifidus milk was not due to the reduction of the intestinal populations of the pathogenic bacteria.

Animals↗
PubMed1999

Protection by short-chain fatty acids against 1-beta-D-arabinofuranosylcytosine-induced intestinal lesions in germfree mice.

In germfree mice, the administration of short-chain fatty acids (SCFA) protected the intestinal mucosa from damage produced by 1-beta-D-arabinofuranosylcytosine (Ara-C). Animals receiving SCFA and Ara-C had intestinal morphologies closer to normal than the control animals, which had severe intestinal lesions. We concluded that orally administrated SCFA reduce intestinal lesions, improving the mucosa pattern of the small intestine and colon.

Administration, Oral↗
PubMed1999

Coinfection with Toxoplasma gondii inhibits antigen-specific Th2 immune responses, tissue inflammation, and parasitism in BALB/c mice infected with Leishmania major.

Lesion size, cellular infiltration, and tissue parasitism in the footpads of BALB/c mice infected with Leishmania major were all dramatically inhibited during acute but not chronic infection with Toxoplasma gondii. Similarly, acute but not chronic toxoplasmosis at the time of infection with L. major had a strong inhibitory effect on development of acquired immune responses mediated by Th2 lymphocytes. In contrast, no major changes in Leishmania-specific Th1-mediated responses were observed in mice coinfected with T. gondii.

Animals↗
PubMed1998

Experimental root canal infections in conventional and germ-free mice.

A small animal model was evaluated to study the interrelationships between microorganisms after their implantation in root canals (inferior central incisors) using germ-free (GF) and conventional (CV) mice. The selected microorganisms were: Porphyromonas endodontalis (ATCC 35406), Eubacterium lentum (ATCC 25559), Peptostreptococcus anaerobius (ATCC 27337), Fusobacterium nucleatum (ATCC 10953), Escherichia coli (ATCC 25922), and Enterococcus faecalis (ATCC 4083). Only P. anaerobius, E. coli, and E. faecalis, respectively, were able to colonize when inoculated alone into the root canal of both CV and GF mice. E. lentum, when inoculated alone colonized only in CV animals. P. endodontalis and F. nucleatum were unable to colonize in CV and GF animals after single inoculation. It is concluded that the experimental animal model presented herein is valuable for ecological studies of root canal infections and that only some strict anaerobic bacteria are able to colonize mice root canals when inoculated by themselves alone in pure culture.

Animals↗
PubMed1998

Dose effect of oral Saccharomyces boulardii treatments on morbidity and mortality in immunosuppressed mice.

Survival, weight loss, translocation and histological alterations in the terminal ileum, liver and spleen were studied in mice simultaneously immunosuppressed with cyclophosphamide and treated or not with Saccharomyces boulardii until the death of all animals. The animals were divided into five groups: C1 (not immunosuppressed, not treated); C2 (immunosuppressed, not treated); B1 (immunosuppressed, treated with S. boulardii 10.0 mg); B2 (immunosuppressed, treated with S. boulardii 1.0 mg) and B3 (immunosuppressed, treated with S. boulardii 0.1 mg). Survival was higher in group B3 than in the other immunosuppressed groups. Weight loss was observed for all groups except C1. By day 7, some animals from each group were killed by ether inhalation for the determination of bacterial translocation and histopathological examination. Bacterial translocation to the liver was lower in groups C1 and B3 than in the other groups. The highest translocation to the liver and spleen was observed in group B1. Low S. boulardii translocation was observed in some animals, principally to the mesenteric lymph nodes. Histopathological examination showed a decrease in epithelial cell turnover with villus length reduction and loss of brush borders in group C2. Relative protection against these alterations was obtained when the animals were treated with the yeast, independently of the dose. Higher expression of the lymphoid component was also noted in the ileal lamina propria, liver and spleen of mice treated with the yeast, together with activation of the reticulo-endothelial system, when compared with group C2 where lymphocyte depletion was observed. This study suggests a relative protection of immunosuppressed animals by treatment with S. boulardii, but this phenomenon was inversely proportional to the yeast dose.

Animals↗
PubMed1998

Intracellular signal triggered by cholera toxin in Saccharomyces boulardii and Saccharomyces cerevisiae.

As is the case for Saccharomyces boulardii, Saccharomyces cerevisiae W303 protects Fisher rats against cholera toxin (CT). The addition of glucose or dinitrophenol to cells of S. boulardii grown on a nonfermentable carbon source activated trehalase in a manner similar to that observed for S.cerevisiae. The addition of CT to the same cells also resulted in trehalase activation. Experiments performed separately on the A and B subunits of CT showed that both are necessary for activation. Similarly, the addition of CT but not of its separate subunits led to a cyclic AMP (cAMP) signal in both S. boulardii and S. cerevisiae. These data suggest that trehalase stimulation by CT probably occurred through the cAMP-mediated protein phosphorylation cascade. The requirement of CT subunit B for both the cAMP signal and trehalase activation indicates the presence of a specific receptor on the yeasts able to bind to the toxin, a situation similar to that observed for mammalian cells. This hypothesis was reinforced by experiments with 125I-labeled CT showing specific binding of the toxin to yeast cells. The adhesion of CT to a receptor on the yeast surface through the B subunit and internalization of the A subunit (necessary for the cAMP signal and trehalase activation) could be one more mechanism explaining protection against the toxin observed for rats treated with yeasts.

Animals↗
PubMed1997

Oral administration of short-chain fatty acids reduces the intestinal mucositis caused by treatment with Ara-C in mice fed commercial or elemental diets.

Swiss mice fed commercial or elemental diets and an oral short-chain fatty acid (SCFA) solution or saline were treated with the cytostatic drug Ara-C (cytarabine, 3.6 mg/mouse/day) for two or four days. Histopathological examination revealed less damage (atrophy, inflammation, or necrosis) to the small intestine and colon caused by Ara-C when SCFA was administered. Accordingly, protein and nucleotide concentrations in the intestinal mucosa were higher in the group receiving SCFA than in the group receiving a placebo of the same pH and osmolarity. Improvement by SCFA treatment was correlated with an increase in the height of the intestinal villi, with no alterations of the crypts. Furthermore, the number of intraepithelial lymphocytes was similar to normal values in animals receiving SCFA and Ara-C. When large doses of SCFA were administered, xanthomized enterocytes appeared, suggesting an accumulation of fatty acids in these cells. We conclude that oral administration of SCFA at close to physiological proportions reduces the inflammation and necrosis caused by Ara-C administration, thus representing a potential factor for the improvement of patients with mucositis caused by cancer treatment.

Administration, Oral↗
PubMed1996

Body distribution of Tityus serrulatus scorpion venom in mice and effects of scorpion antivenom.

In the present study we report the distribution of Tityus serrulatus scorpion venom in serum and various tissues of CFI mice and the efficacy of antivenom in reducing venom concentration. The animals were injected s.c. with 10 micrograms of scorpion venom, divided into groups of four animals and killed at different times from 15 min to 24 hr. Blood samples and samples of different tissues (heart, lung, liver, kidney, spleen, brain and injection site) were collected. Maximum venom levels occurred at 15 min in the kidney and liver and at 30 min in serum, lung, heart and spleen. After 2 hr the venom decreased rapidly in serum and in all other organs until venom levels were no longer detectable after 8 hr. No venom was detected in the central nervous system. In another experiment, 10 microliters of scorpion antivenom was injected i.v. together with the venom, and a rapid reduction of venom concentration was observed in the blood and tissues. In the third experiment, anti-scorpion venom was injected i.v. 1 hr after venom administration, and partial reduction of venom concentration was detected in tissues (lung and kidney). These studies contribute to the elaboration of more objective treatment that may result in a more economic, efficient and controlled use of scorpion antivenom in stings involving humans.

Animals↗
PubMed1996

Effect of Saccharomyces boulardii against experimental oral infection with Salmonella typhimurium and Shigella flexneri in conventional and gnotobiotic mice.

Saccharomyces boulardii was shown to be capable of inhibiting multiplication of enteropathogenic bacteria in vitro and is currently used for its anti-diarrhoea properties. We studied the capacity of this yeast to antagonize Salmonella typhimurium and Shigella flexneri in the intestinal tract of conventional or gnotobiotic NMRI mice. Conventional animals were given daily 10 mg doses of S. boulardii, whereas germ-free animals were given a single 10 mg dose. Both groups were challenged orally 5 d later with the pathogenic bacteria (10(8) or 10(2) viable cells, respectively). Control groups were treated with saline instead of S. boulardii. Mortality and/or histopathological data showed a protective effect against the pathogenic bacteria in yeast-treated mice. Saccharomyces boulardii colonized the digestive tract of gnotobiotic mice and the number of viable cells ranged around 10(10) g-1 of faeces. In experimental and control gnotobiotic animals, Salm. typhimurium and Sh. flexneri became rapidly established at a level of about 10(10) viable cells g-1 of faeces and remained at high levels until the animals died or were sacrificed. The protection against Salm. typhimurium and Sh. flexneri obtained in conventional and/or gnotobiotic mice previously associated with S. boulardii is not due to the reduction of the bacterial populations in the intestines.

Administration, Oral↗
PubMed1995

Protective effect of Saccharomyces boulardii against the cholera toxin in rats.

The effect of orogastric administration of Saccharomyces boulardii on the anatomopathological aspect of the jejunal villi was studied in male Fischer rats (weighing about 40 g) orogastrically infected with a culture of Vibrio cholerae. Experimental and control groups received lyophilized S. boulardii (25 mg suspended in 0.5 ml saline) or 0.5 ml saline, respectively, three times a day for 10 days by gastric intubation. On day 5 of treatment, 0.5 ml of a culture of V. cholerae containing 10(8) viable cells was inoculated by gastric intubation into both groups. Histopathological examination of the jejunal mucosa showed extensive lesions of the superficial epithelium of the villi from the control group whereas few lesions of this superficial epithelium were observed in the experimental group. These data show that the inhibition of the action of the cholera toxin on enterocytes by S. boulardii suggested by recent results in vitro can be demonstrated in vivo.

Animals↗
PubMed1993

Vitamin D overload and experimental Trypanosoma cruzi infection: parasitological and histopathological aspects.

1. Six groups of 45-day-old, 23.0 +/- 1.7 g, female Balb/c mice were inoculated intraperitoneally with 63, 252, 440, 630, 2520 or 6300 I.U. of vitamin D for 6 days. A seventh group was inoculated with saline. Each group consisted of 30 animals. 2. All animals inoculated with the doses of 2520 and 6300 and 70% of mice which received 630 I.U. of vitamin D died 21 days after the first administration of the vitamin. The LD50 was 630 I.U. 3. The survivors were divided into two groups inoculated intraperitoneally with 5000 trypomastigotes of either Y or CL strain of Trypanosoma cruzi. 4. Based on the survival index on day 73 after infection, Vitamin D gave statistically significant protection (P < 0.01) for mice inoculated with doses of 63 or 430 I.U. of Y or CL strains, respectively. 5. On histopathological examination, inflammatory reaction and cellular and tissue parasitism were less intense in animals which received higher doses of vitamin D. 6. It is concluded that an overload of vitamin D had a protective effect against CL and Y strains of Trypanosoma cruzi infection in Balb/c mice.

Animals↗
PubMed1993

The effect of iron nutritional status on Trypanosoma cruzi infection in germfree and conventional mice.

1. Conventional (CV) and gnotobiotic (GN) female CFW mice were infected with the Y strain of Trypanosoma cruzi. 2. After infection, both CV and GN groups received injections of iron-dextran or desferrioxamine. Non-injected mice served as controls. 3. The parasitemia was more intense in iron-dextran-treated mice. 4. The iron levels in serum, liver, and spleen were: (a) not decreased by desferrioxamine and (b) increased by iron-dextran treatments. 5. An increase in leukocyte numbers was observed in all GN and CV groups after infection. 6. There was no difference in total iron binding capacity (TIBC) and iron saturation transferrin (IST) between GN and CV mice before infection. 7. In CV groups, after infection, TIBC was decreased whereas the levels of IST were increased; in GN the opposite occurred. 8. Trypanosome-specific IgG and IgM antibody levels were raised in the GN group but not in the CV group.

Animals↗
PubMed1992

Effect of dietary chitin on cholesterol absorption and metabolism in rats.

The effect of chitin at the level of 5% in the diet on cholesterol absorption and metabolism was studied in Wistar rats fed on diet containing beef tallow (7%) and cholesterol (1%). When compared with pair-fed controls, rats fed on diet containing chitin had: (1) similar weight gain and feed efficiency, (2) lower apparent protein digestibility, (3) equivalent liver steatosis, (4) reduced levels of liver triglycerides and cholesterol, (5) similar levels of serum and fecal cholesterol, (6) higher excretion of triglycerides in feces.

Absorption↗
PubMed1992

Intragastric infection of conventional and germfree mice with Giardia lamblia.

The effects of experimental infection with Giardia lamblia were studied in 30-day old conventional and germfree CFW mice (7 animals in each group) of both sexes. Cysts were observed in the feces of both groups 6 to 7 days after intragastric infection of each animal with about 2.5 x 10(5) G. lamblia trophozoites. Fecal cyst level was statistically higher in germfree mice (about 10(5) cysts/g feces) when compared with the conventional group (about 10(4) cysts/g feces). The peak of infection in the conventional group apparently occurred on the 10th day after infection as indicated by an increase of fecal weight and by histopathological examination. Intense infiltration of the lamina propria and high reactional hyperplasia of the lymphoid component were observed in the conventional group. There was no infiltration or hyperplasia in germfree infected mice and fecal weight was relatively constant throughout the experiment. These results suggest that, as is the case for other intestinal pathogenic protozoa, the intestinal microflora is indispensable for the expression of the pathogenicity but not for the multiplication of G. lamblia.

Animals↗
PubMed1992

The acute phase of experimental infection with Trypanosoma cruzi is more severe in mice monoassociated with strict anaerobic bacteria.

1. The influence of some components of the normal human intestinal flora on the acute phase of experimental infection with strain CL of Trypanosoma cruzi was studied in 30-day-old germ-free or gnotobiotic CFW (LOB) mice monoassociated with Bacteroides fragilis, Peptostreptococcus sp or Clostridium sp by intragastric inoculation of 10(6) bacteria 10 days before the intraperitoneal infection with 5 x 10(3) trypomastigotes/g body weight. 2. Significantly earlier parasitemia peak and mortality were observed in Bacteroides fragilis- and Clostridium-associated mice (16.75 +/- 0.96 and 15.00 +/- 1.15 days, respectively) when compared with germfree animals (18.83 +/- 1.17 days). More precocious mortality (10.40 +/- 2.06 days) and, curiously, much lower blood parasitemia were observed in Peptostreptococcus-associated mice than in other gnotobiotic mice. 3. The extent of cardiac tissue parasitism decreased in the following order: germfree, B. fragilis-associated, Clostridium-associated, and Peptostreptococcus-associated animals. The levels of inflammatory reaction decreased in the following order: germfree, Peptostreptococcus-associated, Clostridium-associated, and B. fragilis-associated mice. 4. These results show that the acute phase of experimental infection with T. cruzi was more severe in mice associated with strict anaerobic bacteria when compared with germfree animals. This suggests that a normal intestinal flora may be another factor, in addition to nutritional and genetic factors, responsible for the different susceptibility of organisms of the same species infected with T. cruzi.

Acute Disease↗