Search PubMed⌕ Search

Biomedical subjects

D Rodríguez

Publications and source records attributed to D Rodríguez.

At least 73 records · Page 4Linked to original sources
PubMed1995

[Immunoperoxidase in the studies of immune thrombocytopenias].

The usefulness of different techniques to measure platelet bound IgG has been reviewed by George. We present here the results obtained with a technique designed to measure membrane bound IgG employing an anti-human IgG labeled with peroxidase and using O-dianisidine-H2O2 to reveal the enzymatic activity. We studied 152 patients with chronic autoimmune thrombocytopenic (ATP) including 120 adults and 32 children (age below 15 years old), diagnosed by exclusion of diseases that may be associated with thrombocytopenic purpura of either immune or nonimmune mechanisms. Besides, 79 patients with thrombocytopenia related to other diseases were also evaluated. The normal values in 215 controls were 188 +/- 4 IgG molec/platelet (mean +/- SE), while in the whole population of chronic ATP the results were 4714 +/- 344, p < 0.001. In pediatric cases the results had a tendency to values higher than in adults. A negative correlation was found between the number of platelets and the amount of bound IgG, r = 0.41 p < 0.001. IgG bound platelets were also increased in treated patients at relapse. The percent of normal IgG bound platelet was 4.5% in patients with a platelet count below 50,000/microliters and 39% in those with normal platelet number. Patients with secondary thrombocytopenia had elevated IgG/platelet while the values were normal in patients with thrombocytopenia of unknown etiology. We conclude that the immunoperoxidase technique is useful to establish the immunologic nature of thrombocytopenia.

Age Factors↗
PubMed1994

Protein kinase C-mediated phospholipase D activity is increased by linolenic acid supplementation in NG 108-15 cells.

Phospholipase D activation was studied in NG 108-15 cells after manipulation of the phospholipid fatty acid composition. Cultivation of cells in media containing different polyunsaturated fatty acids induced extensive and specific changes in the phospholipid fatty acid composition. General for all phospholipids was an increase in polyunsaturated fatty acids at the expense of monounsaturated fatty acids. To examine phospholipase D activation, cells were stimulated with phorbol esters in the presence of ethanol and the formation of phosphatidylethanol was analyzed. In cells cultured with linolenic acid, a significantly higher amount of phosphatidylethanol was formed compared to control cells. On the other hand, supplementation with linoleic, arachidonic or docosahexaenoic acids did not induce any changes in phospholipase D activity. The effect was not due to free fatty acids in the cell culture medium and thus probably induced by fatty acids incorporated into membrane phospholipids or fatty acid metabolites. The results indicate a specific effect of linolenic acid and/or its metabolites on protein kinase C-mediated phospholipase D activity.

Cell Line↗
PubMed1994

[Application of immunologic methods to the analysis of bio-leaching bacteria].

Pure cultures of Thiobacillus ferrooxidans and mixed cultures of Thiobacillus ferrooxidans and Leptospirillum ferrooxidans isolated from the Matahambre mine (Cuba) were used to fit immunodiffusion and immunoelectron microscopy to the study of iron oxidizing bacteria. The possibilities, advantages and limits of those techniques have been studied from both the identification and the serological characterization points of view. Finally, the efficiency of these methods was tested by applying them to the identification of microorganisms from acidic waters from the mine.

Animals↗
PubMed1993

Peroxynitrite-mediated cytotoxicity to Trypanosoma cruzi.

Macrophages produce and release superoxide anion (O2.-) and nitric oxide (.NO) as part of their microbicidal effector molecules. The simultaneous production of O2.- and .NO results in the rapid formation of peroxynitrite anion (ONOO-) by macrophages. Peroxynitrite is a strong oxidant with a half-life of less than 1 s in biological systems. There is solid experimental evidence implicating .NO and O2.- in macrophage-induced cytotoxicity against bacteria, parasites, and tumor cells. However, the cytotoxic role of peroxynitrite in these processes remains to be studied. In this work we demonstrate the parasiticidal activity of ONOO- against Trypanosoma cruzi. Peroxynitrite was highly trypanocidal, killing T. cruzi in a dose-dependent manner. Addition of 500 microM ONOO- as a single bolus resulted in 50% inhibition of cell proliferation as followed by growth curves. Fifty percent inhibition of [3H]thymidine incorporation measured at 6 h postaddition of ONOO- was obtained at 150 microM. Addition of ONOO- as a continuous infusion rather than a single bolus resulted in an even stronger inhibition in cell growth. Other cytotoxic effects of ONOO- included cellular swelling and inhibition of cell motility. Classical hydroxyl radical scavengers and metal chelators afforded minimal protection against ONOO(-)-mediated cytotoxicity, indicating that peroxynitrite anion itself, rather than the .OH-like oxidant derived from its proton-catalyzed decomposition, was the main damaging species. From literature data we estimated the production of ONOO- by activated macrophages inside phagolysosomes to be around 500 microM/min. Therefore, our results demonstrate that ONOO- may operate in vivo as a critical macrophage-derived reactive intermediate against T. cruzi.

Animals↗
PubMed1993

[Doppler velocimetry: perinatal results according to an integral evaluation of resistances].

The experience with 180 high-risk pregnancies evaluated with Doppler velocimetry in Rancagua Regional Hospital, classified according to an original integral resistance evaluation table, is presented. Perinatal outcome is analyzed in relation to this classification, demonstrating a high correlation between progressive increase of resistance and poor perinatal outcome, evidenced as proportion of SGA newborns, non-reactive NST, low five-minute Apgar score, admission to neonatology or perinatal death, with good sensibility, specificity and predictive values.

Adolescent↗
PubMed1992

Thiobacillus ferrooxidans detection using immunoelectron microscopy.

A specific, fast and very sensitive immunoelectron microscopy method was developed to morphologically and serologically distinguish different cultures of iron oxidizers. Bacteria isolated from the acidic waters of "Matahambre" and "Mina Delita" mines (Cuba) were characterized. An antiserum specific to Thiobacillus ferrooxidans did not react with other bacteria also present in the acidic waters of mine drainage. Our results suggest the occurrence of some strains of Thiobacillus ferrooxidans, Thiobacillus thiooxidans and Leptospirillum ferrooxidans in these waters.

Antibodies, Bacterial↗
PubMed1991

The influence of environment and parasitism on the prevalence of asthma in two Venezuelan regions.

The point prevalence of bronchial asthma and the influence of environmental conditions among 100 individuals chosen from two Venezuelan regions, i.e., rural and urban, were investigated by history, routine laboratory tests, determination of total and specific IgE antibody to common allergens and spirometric tests. The point prevalence of bronchial asthma was 3.0% in rural subjects who were also highly parasitized by helminths and 3.6% in subjects from the urban region. A significative difference in skin responses to Dermatophagoides pteronnysinus was observed in urban asthmatics when compared with rural asthmatics. A similar response to selected allergens was found among both populations. The prevalence of infestation by Ascaris in rural asthmatics was high compared with that of rural controls. Total IgE levels were elevated for both populations, but significatively higher (p less than 0.05) for rural individuals. Results suggest a significative point prevalence of bronchial asthma in both regions, despite the helminth infestation of rural subjects. The effects of environmental factors, their concentration and time of exposure are considered as main factors responsible for allergic reactivity observed in the Venezuelan regions studied.

Asthma↗
PubMed1984

Subdural hematomas of the posterior fossa in normal-weight newborns. Report of two cases.

Two cases are reported of subdural hematoma of the posterior fossa in normal-weight full-term newborn infants. The most salient factors in these cases were the lack of specific symptoms and signs indicating the nature and location of the lesion, the importance of computerized tomography for diagnosis, and the good results obtained with early surgical treatment.

Birth Weight↗
PubMed1976

Enzyme histochemistry of rat interfascicular oligodendroglia, with special reference to 5'-nucleotidase.

The interfascicular oligodendroglia of the rat striatum nucleus is studied in control animals and under experimentally induced brain edemas. Enzyme histochemical studies were performed. Normal oligodendrocytes show two different enzymatic distributions. While Mg2+-ATPase, TPPase, TPPase, adenylate cyclase and SDH are shown to be situated at the cell bodies and some proximal processes, 5'-nucleotidase reaction is seen at the cell fine distal processes. In spite of its trong activity in oligodendroglial endings the latter enzyme is not seen at the myelin sheath. This sheath and the interfascicular cells being intimately related, 5'-nucleotidase appears to be important not only during myelination, as almost all authors emphasize, but also in the adult myelin metabolism. Experimental brain edema shows some changes in the interfasicular oligodendroglia enzymatic activites for 5'-nucleotidase, Mg2+-ATPase and adenylate cyclase. A progressive disappearance of the former enzyme is observed. These features and those of derived from local ionic alterations may be concerned with the special susceptibility of white matter for some types of brain swellings.

Animals↗
PubMedDate not supplied

Low cycle fatigue behavior of Ti6Al4V thermochemically nitrided for its use in hip prostheses.

Titanium and its alloys have many attractive properties including high specific strength, low density, and excellent corrosion resistance. Besides, titanium and the Ti6Al4V alloy have long been recognized as materials with high biocompatibility. These properties have led to the use of these materials in biomedical applications. Despite these advantages, the lack of good wear resistance makes difficult the use of titanium and Ti6Al4V in some biomedical applications, like articulating components of prostheses. Some surface treatments are available in order to correct these problems, like thermal surface treatment by means of nitrogen gaseous diffusion at high temperature. Nitrogen enters into the material by diffusion, creating a surface layer of increased hardness. Low cycle fatigue behavior in air of Ti6Al4V alloy has been studied. Results show a reduction of low cycle fatigue life up to 10% compared to the not-treated material. Studies suggest it is not related to the titanium nitride surface layer, but to microstructural changes caused by the high temperature treatment.

Journal Article↗