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Biomedical subjects

D Feder

Publications and source records attributed to D Feder.

31 records · Page 2Linked to original sources
PubMed1983

Quality of stone dies produced by different impression materials. A comparative study of impression techniques.

A comparison was made of the ability of different impression materials to depict precision made steel blocks. Stone dies poured into such impressions were studied concerning their hardness, dimensional accuracy, detail reproduction, and surface reproduction. The dies were produced in the impression material only to a small extent, with the exception of their surface roughness. Differences between impression materials are otherwise small. The advantages of two-phase alginates over standard alginates lie in the impression technique rather than in the characteristics of the material.

Chemical Phenomena↗
PubMedDate not supplied

Isolation of Serratia marcescens in the midgut of Rhodnius prolixus: impact on the establishment of the parasite Trypanosoma cruzi in the vector.

The effects of resident bacteria in the stomach of 5th-instar larvae of Rhodnius prolixus on the erythrocyte lysis and Trypanosoma cruzi infection were studied. The bacteria population increased approximately 10,000-fold after feeding. Hemolysis rose to approximately 28% within 24h postfeeding and then linearly grew until day 4 attaining almost 100%. The number of surviving Y strain of T. cruzi in the stomach declined drastically, while the infection with Dm28c clone was maintained stable. Five days after feeding, few different types of bacterial colonies were obtained when stomach content suspensions were spread onto BHI agar plates. The hemolytic bacteria were isolated and identified as Serratia marcescens biotype A1a (referenced as RPH), which produces the pigment prodigiosin. In vitro experiments, comparing incubations of RPH with S. marcescens SM365, a prodigiosin pigment producer, and S. marcescens DB11, a nonpigment variant, as a control, with erythrocytes and T. cruzi demonstrated that: (i) at 30 degrees C, SM365 and RPH diminished the populations of Y strain, but not DM28c clone, and DB11 was unable to lyse both T. cruzi strains; (ii) at 0 degrees C, SM263 and RPH killed the flagellates, but DB11 did not; and (iii) all three strains of S. marcescens were able to lyse erythrocytes. These results suggest that S. marcescens trypanolytic activity from the SM365 and RPH strains is distinct from the hemolytic activity and that prodigiosin is an important factor for the trypanolytic action of the bacteria.

Animals↗
PubMedDate not supplied

Short- and long-term effects of azadirachtin A on development and egg production of Rhodnius prolixus.

Azadirachtin A was given through a blood meal to 4th-instar larvae and to adult females of Rhodnius prolixus. Development (ecdysis) and egg production were inhibited in a dose-dependent manner. Long-term experiments with subsequent four feedings on azadirachtin-free blood were performed with 4th-instar larvae and with adult females. Only in the low-dose azadirachtin larval groups (0.01 and 0.1 microgram/ml of blood), development was partially restored; after a single 1.0 microgram/ml treatment about 50% of the treated larvae were still alive 120 days later without any adult emergence. Similarly fed females had a dose-dependent lower survival and egg deposition rate. The results are discussed in relation to the mode of azadirachtin A action.

Animals↗
PubMedDate not supplied

Haemolymph and fat body metallo-protease associated with Enterobacter cloacae infection in the bloodsucking insect, Rhodnius prolixus.

Analysis of zymograms with SDS-polyacrilamide gel electrophoresis containing gelatin as substrate, and performed on samples of haemolymph or fat body taken from Rhodnius prolixus inoculated or not with Enterobacter cloacae, demonstrated distinct patterns of protease activities: (i) in the haemolymph two proteases were induced in insects inoculated with bacteria; (ii) two proteases were detected in the fat bodies derived from non-inoculated controls or insect inoculated with sterile culture medium; (iii) haemolymph and fat body had both the same apparent molecular weights proteases (46 and 56 kDa); and (iv) these enzymes were characterized as metallo-proteases. The association of these enzymes in Rhodnius infected with bacteria was discussed.

Animals↗
PubMedDate not supplied

Metalloproteases in Trypanosoma rangeli-infected Rhodnius prolixus.

Protease activities in the haemolymph and fat body in a bloodsucking insect, Rhodnius prolixus, infected with Trypanosoma rangeli, were investigated. After SDS-polyacrylamide gel electrophoresis containing gelatin as substrate, analysis of zymograms performed on samples of different tissues of controls and insects inoculated or orally infected with short or long epimastigotes of T. rangeli, demonstrated distinct patterns of protease activities: (i) proteases were detected in the haemolymph of insects which were fed on, or inoculated with, short epimastigotes of T. rangeli (39 kDa and 33 kDa, respectively), but they were not observed in the fat body taken from these insects; (ii) protease was also presented in the fat bodies derived from naive insects or controls inoculated with sterile phosphate-saline buffer (49 kDa), but it was not detected in the haemolymph of these insects; (iii) no protease activity was observed in both haemolymph and fat bodies taken from insects inoculated with, or fed on, long epimastigotes of T. rangeli. Furthermore, in short epimastigotes of T. rangeli extracts, three bands of the protease activities with apparent molecular weights of 297, 198 and 95 kDa were detected while long epimastigotes preparation presented only two bands of protease activities with molecular weights of 297 and 198 kDa. The proteases from the insect infected with T. rangeli and controls belong to the class of either metalloproteases or metal-activated enzymes since they are inhibited by 1,10-phenanthroline. The significance of these proteases in the insects infected with short epimastigotes of T. rangeli is discussed in relation to the success of the establishment of infection of these parasites in its vector, R. prolixus.

Adipose Tissue↗
PubMedDate not supplied

[Action of 3,5,3'-triiodothyronine (T3) on Walker's 256 carcinosarcoma development].

In order to verify the effects of triiodothyronine (T3) administration in animals bearing Walker tumor, the authors have carried out an experimental study utilizing Wistar rats inoculated with both ascitic and solid Walker tumor, and Balb/c isogenic mice for the study of spreading of macrophages. The animals were treated with T3 20 micrograms/100 g of body weight and the data were analysed by Chi-square and Mann-Whitney tests. The authors conclude that T3 increases significantly the survival of rats bearing Walker tumor, and the spreading of macrophages when inoculated into the peritoneal cavity of mice. The hormone does not alter the weight of tumor mass. These results could be explained by the macrophageal activation and by the synthesis of the tumor necrosis factor.

Animals↗
PubMedDate not supplied

Study of interactions between Listeria monocytogenes and experimental tumors.

OBJECTIVE: to verify the effects of Listeria monocytogenes (LM) inoculation in the survival of animals bearing Ehrlich's tumor. KIND OF STUDY: experimental. Animals-isogenic mice, Balb/c, female, 19-21 g. Tumor-Ascitic Ehrlich's tumor, dilution of 5 x 10(5) cells/0.1 ml. Bacteria-LM serotype 4a, solution with 7 x 10(3) bacteria (standard sub-lethal dose). Intervention-a) inoculation of LM in mice bearing Ehrlich tumor at the same time as ascitic cells transplantation. b) inoculation of LM seven days before and, again, seven and fourteen days after ascitic cells transplantation. c) to study the effect of using ampicillin 100 mg/kg, im, simultaneously with the inoculation of Ehrlich tumor and LM organisms and, again, 3, 5, 7, 14, 21 and 30 days after the ascitic cells transplantation. ANALYSIS: Chi-square test; p < 0.05 RESULTS AND CONCLUSION: LM increases significantly the survival of mice bearing Ehrlich tumor even when only one inoculum of viable LM was used, seven days before or seven days after the ascitic cells transplantation. The use of ampicillin after the inoculation of LM and tumor transplantation does not alter the survival of mice.

Ampicillin↗
PubMedDate not supplied

[Effects of H2 blockers on the spreading of macrophages in vitro].

PURPOSE: To verify if cimetidine, ranitidine, and famotidine, when inoculated by ip route in mice, do enhance macrophage activation and whether or not such activation is altered with prior use of sodium thioglycolate. KIND OF STUDY: Experimental. ANIMALS: isogenic, Balb/c mice, 19-21 g. INTERVENTION: The authors used 8 groups of 10 animals. The mice were treated by ip route with cimetidine (100 mg/kg), ranitidine (62.5 mg/kg), and famotidine (50 mg/kg), and were compared to a control group (saline). The method of spreading of macrophages was applied twenty-four hours after the inoculation. The same procedure was repeated on a later stage in groups submitted to a prior treatment with sodium thioglycolate (15 mg/kg). EVALUATION: Kruskal-Wallis and Mann-Whitney's tests were used. RESULTS: Inoculation of anti-H2 drugs in the peritoneal cavity of mice significantly enhances the spreading of macrophages independently of the presence of a peritoneal irritant.

Animals↗
PubMedDate not supplied

[Idiopathic pulmonary hemosiderosis in the adult: a case report].

The case of idiopathic pulmonary hemosiderosis in a 20 year old male is presented. Iron deficiency anemia, recurrent hemoptysis and micronodular infiltrate in lower lung areas were the most important signs observed. The transbronchial biopsy showed alveolar and interstitial hemorrhage and hemosiderin in the pulmonary macrophages. Treatment was started with prednisone, but the addition of immunosuppressive drugs (cyclophosphamide) was needed, followed by a clinical remission.

Adult↗
PubMedDate not supplied

[Hemodynamic and pulmonary effects of nifedipine].

The authors reviewed the actions of nifedipine, a blocker of calcium channels, on the systemic and pulmonary circulation. The mechanism of action of the drug on the systemic and pulmonary circulation and on the gas exchange is discussed. The main effects of nifedipine on the coronary circulation and indications for therapeutic use of the drug are discussed on the topics of coronary insufficiency, systemic and pulmonary blood hypertension, acute respiratory failure, and Raynaud's phenomenon.

Animals↗
PubMedDate not supplied

[Pulmonary hypertension in adult respiratory distress syndrome: review of the literature].

This paper is a review of clinical and experimental studies on pulmonary hypertension in acute respiratory distress syndrome (ARDS) and its consequences on the outcome of such syndrome. The most probable causes: hypoxic pulmonary vasoconstriction, vasoconstriction provoked by vasoactive substances, extra and intraluminal occlusions are discussed. The authors also discuss the action of vasoactive drugs on the pulmonary circulation and on the pulmonary gas exchange.

Animals↗