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R Díaz

Publications and source records attributed to R Díaz.

At least 73 records · Page 4Linked to original sources
PubMed1993

Factors affecting detection of Brucella melitensis by BACTEC NR730, a nonradiometric system for hemocultures.

The detection of Brucella bacteremia by subculture does not always correlate with a positive signal in the BACTEC NR730 nonradiometric system (Becton Dickinson Diagnostic Instrument Systems, Sparks, Md.). The effect of the inoculum size, pH, sodium polyanetholesulfonate, carbon sources (i-erythritol, sodium pyruvate, monosodium glutamate, D-glucose, and L-alanine), and urea in the release of CO2 was evaluated by using the reference strain Brucella melitensis 16M. In standard NR6 vials with or without blood, inocula 5 to 10 times larger (at least 265 CFU per vial) than those usually found in the blood of patients with brucellosis were necessary to produce a positive growth value (GV) in 4 days or less, and similar results were obtained with vials supplemented with the substrates listed above. GVs were consistently lower in vials with sodium polyanetholesulfonate than in vials without this agent. Vials with no blood inoculated with 265 CFU per vial showed turbidity 1 day before GVs became positive, proving that the major limiting detection factor was the low level of release of CO2 and not an inadequate growth medium. In NR6 vials buffered to pH 6.2, GVs became positive faster and were higher than those in standard vials. NR6 vials at pH 6.2 with 0.3% sodium pyruvate yielded a positive GV in the first day of bacterial turbidity.

Alanine↗
PubMed1992

Differential binding of wild-type and a mutant RepA protein to oriR sequence suggests a model for the initiation of plasmid R1 replication.

DNA replication of the enterobacterial plasmid R1 is initiated by RepA protein. We have developed a new procedure for the purification of RepA from inclusion bodies, which involves CHAPS-mediated solubilization. This method has been also used for the thermosensitive mutant protein RepA2623. The nucleoprotein complexes obtained with both proteins and oriR, the origin of replication, are studied in this paper. DNaseI and hydroxyl-radical footprinting suggest the presence in oriR of two sites with different affinity for RepA separated by eight helical turns. The pattern of hypersensitive sites in the footprints indicates that the oriR sequence, when complexed with RepA, is curved. The binding of RepA molecules to oriR is co-operative and this co-operativity is defective in the thermosensitive protein. Band-shift analysis of RepA-oriR complexes revealed the existence of a species with an anomalously high electrophoretic mobility that appears after formation of the first RepA-oriR complex and requires the sequential interaction of RepA with its two distal binding sites. These features lead us to propose that protein-protein interactions between RepA bound to both distal sites could be responsible for oriR looping. This model represents a novel mechanism that results in activation of an origin in a replicon that does not contain iterons.

Bacterial Proteins↗
PubMed1992

Genetic and functional analysis of the basic replicon of pPS10, a plasmid specific for Pseudomonas isolated from Pseudomonas syringae patovar savastanoi.

The sequence of a 1823 base-pair region containing the replication functions of pPS10, a narrow host-range plasmid isolated from a strain of Pseudomonas savastanoi, is reported. The origin of replication, oriV, or pPS10 is contained in a 535 base-pair fragment of this sequence that can replicate in the presence of trans-acting function(s) of the plasmid. oriV contains four iterons of 22 base-pairs that are preceded by G+C-rich and A+T-rich regions. A dnaA box located adjacent to the repeats of the origin is dispensable but required for efficient replication of pPS10; A and T are equivalent bases at the 5' end of the box. repA, the gene of a trans-acting replication protein of 26,700 Mr has been identified by genetic and functional analysis. repA is adjacent to the origin of replication and is preceded by the consensus sequences of a typical sigma 70 promoter of Escherichia coli. The RepA protein has been identified, using the minicell system of E. coli, as a polypeptide with an apparent molecular mass of 26,000. A minimal pPS10 replicon has been defined to a continuous 1267 base-pair region of pPS10 that includes the oriV and repA sequences.

Amino Acid Sequence↗
PubMed1992

Platelet alpha 2-adrenoceptor density in pregnancy-induced hypertensive patients: effect of epidural analgesia.

OBJECTIVES: Although pregnancy induced hypertension (PIH) is an important and relatively common medical problem, its pathophysiology remains unresolved and the search for a biochemical marker that precedes the hemodynamic abnormalities of PIH continues. Since human platelets contain alpha 2-adrenoceptors, these receptors were measured in women with PIH to determine whether patients with PIH have alpha 2-adrenoceptor abnormalities that might cause or exacerbate the hypertensive process. The effect of epidural analgesia upon blood pressure and its relation to changes in platelet alpha 2-adrenoceptor density were also investigated. DESIGN: Biochemical measurements and radioligand binding assays in platelets were performed on 33 patients with the criteria for PIH and on 26 healthy pregnant women. RESULTS: Blood pressure was significantly elevated in hypertensive women when compared with normotensive pregnant women although, in this group, blood pressure returned to normal levels in response to epidural analgesia. In drug-free hypertensive patients, the specific binding of 3H-yohimbine to platelet membranes increased significantly compared with that in control pregnant subjects. In contrast, the dissociation constant was not significantly different in the two groups. Furthermore, alpha 2-adrenoceptor density in the group with PIH returned to normal levels in response to epidural analgesia. CONCLUSION: Our findings indicate that PIH is characterized by an exaggerated response of platelet alpha 2-adrenoceptor density to a rise in blood pressure and that this alteration could be significant in the pathogenesis of hypertension. Furthermore, human alpha 2-adrenoceptors undergo regulatory mechanisms similar to those recently described for adrenergic receptors in a variety of animal models.

Adult↗
PubMed1992

[Isolation of Yersinia enterocolitica 0:8 in Spain].

BACKGROUND: We presented three cases of enterocolitis due to Yersinia enterocolitica 0:8. METHODS: We use common isolation media, pathogenicity markers and plasmid analysis. RESULTS: The study of genetic and biochemical characteristics of the strains showed that they belonged to 1B biotype, 0:8 serotype, and that they not carry the virulence plasmid. However, they have pathogenicity markers that were considered typical of highly virulent strains. SUMMARY: This are the first isolations of this particular serotype in Spain and they showed, as it happens in other European countries, the spread of serotype 0:8 around the world.

Acute Disease↗
PubMed1992

[Creutzfeldt-Jakob disease. The first case with histopathological study in Panama].

We studied the clinical and histopathology findings of the first proved case of Creutzfeldt-Jakob disease in Panama. A sixty-five-years-old female patient referred from Santiago de Veraguas was admitted to Santo Tomás Hospital with a progressive clinical picture of dementia, incoordination and generalized myoclonia. The electroencephalogram showed periodic paroxysmal activity. The patient died eight months after initiated the disease. The cerebral histopathologic study was characteristic of Creutzfeldt-Jakob disease: status spongiform, neuronal loss and non-inflammatory gliosis was found.

Aged↗
PubMed1991

Protection against the lethal effect and arthritogenic capacity of Yersinia enterocolitica serovar O:3 for mice.

Protection against the intravenous lethal effect of Yersinia enterocolitica serovar O:3 for mice can be achieved by oral immunization with bacteria expressing the O:3 lipopolysaccharide (LPS). Under similar experimental conditions, Ca(2+)-dependent cells are more protective than their Ca(2+)-independent counterparts, live vaccines are more efficacious than killed ones, and parenteral immunization is more efficient than the oral route. Antibodies induced by enzyme-treated LPS from an O:3 strain are able to mediate protection against challenge with one homologous strain, but they do not prevent induction of arthritis.

Administration, Oral↗
PubMed1991

[Obtainment of pineapple juice powder by foam-mat drying].

The foam-mat production and stability using pineapple juice concentrate (25, 30 and 40 degrees Brix), adding a surfactants mixture and maltodextrin (DE 10) as co-adjuvant, stirred in a commercial mixer, was studied. Adequate foam formation conditions were as follows: concentrate of 25 degrees Brix using surface active agents (Sorbac 60-Polisorbac 80) 0.285% surface active agent/total solids, HLB = 6, and stirring time, 7 min. The foam was dehydrated in an oven dried with a horizontal air flow circulation set at 60, 70 and 80 degrees C using 3, 5 and 10 mm bed depths. The best conditions were obtained at 60 degrees C and 5 mm bed depth. The product had a particle size of sieve 40-80, and a moisture content of 3%. It was then packaged in multilayer plastic film and stored at environmental conditions. No brown color formation or mold growth was detected during storage. Pineapple juice and a refreshing drink were prepared. The general acceptability in a community indicated that 95% of the population involved accepted the product.

Beverages↗
PubMed1991

[Oral infection by Y. enterocolitica 0:8. Studies of immunization in a murine model].

The evaluation and mechanism of protection against Y. enterocolitica O:8 using different immunization schedules. We immunize 3 groups of 20 mice each against an oral lethal dose of Y. enterocolitica O:8 using: 1) whole cells, 2) hyperimmune sera, and 3) LPS and common antigen. Animals immunized using whole live cells that produce common antigen (O:3 +V and IP614) developed the highest degree of protection, with an overall survival rate of 70% and 60% respectively. Similar results were obtained using animals immunized with sera. Animals immunized using LPS and common antigen also were able to control the replication of the infecting strain. Common antigen and antibodies against it did not inhibit adherence not bacterial invasion. However, it seems to be an important protecting factor, that controls the bacterial replication in intestinal lymph tissue. The exact mechanism is currently unknown.

Animals↗
PubMed1990

Cloning vectors, derived from a naturally occurring plasmid of Pseudomonas savastanoi, specifically tailored for genetic manipulations in Pseudomonas.

A minimal replicon of 1.8 kb isolated from a 10-kb plasmid of Pseudomonas savastanoi, pPS10, has been used to obtain a collection of small vectors specific for Pseudomonas (P. savastanoi, P. aeruginosa and P.putida). In addition, shuttle vectors that can be established both in Pseudomonas and Escherichia coli have been constructed by adding a pMB9 replicon. The vectors permit cloning of DNA fragments generated by a variety of restriction enzymes using different antibiotic resistance markers for selection and offer the possibility to screen recombinants by insertional inactivation. This cloning system can be used to establish recombinant plasmids in Pseudomonas either at low or high copy number. pPS10 derivatives are compatible with other Pseudomonas vectors derived from broad-host-range replicons of the incompatibility groups P1, P4/Q and W. Introduction and expression of the iaaMH operon in a P. savastanoi mutant deficient in the production of indoleacetic acid has been achieved using one of these vectors.

Cloning, Molecular↗
PubMed1990

Antibody response to Brucella ovis outer membrane proteins in ovine brucellosis.

Hot saline extracts of Brucella ovis were composed of vesicles with outer membrane proteins (OMPs), lipopolysaccharide, and phospholipid as constituents. Extraction with petroleum ether-chloroform-phenol yielded a protein fraction free of detectable lipopolysaccharide, in which group 3 OMPs (28,500 apparent molecular weight [28.5K], 27.0K, and 25.5K) represented 81% of the total. Group 1 OMPs and 67.0K, 22.5K to 21.5K, and 19.5K to 18.0K proteins were also detected. Adsorption of immune sera with whole bacteria suggested that group 3 OMPs and 67.0K, 22.5K to 21.5K, and 19.5K to 18.0K proteins had antigenic determinants exposed on the surfaces of both B. ovis and rough B. melitensis cells but not on smooth B. melitensis cells. Antibodies to group 3 OMPs and the 67.0K protein in the sera of 93 and 87%, respectively, of B. ovis-infected rams were found by immunoblotting. Antibodies to other proteins were present in 67% of these animals. Compared with B. ovis-infected rams which had not developed lesions, rams with epididymo-orchitis had antibodies to a larger variety of proteins. Although ewes infected with B. melitensis also showed antibodies to OMPs, the immunoblot reactions were less intense.

Adsorption↗
PubMed1990

[Early angiographic study post successful angioplasty. Predictor of late restenosis].

Consecutive prospective coronary angiographies following 24 hours were studied to find early angiographic predictors of post-PTCA restenosis in the follow-up of 71 patients who had been dilated successfully. Conventional cine coronary and quantitative digital angiography was used to analyse the degree of obstruction previous to dilatation following 24 hours and 30 minutes after the procedure. Following 24 hours, angiographic findings showed: Group A: patients having the same lumen as at immediate post-PTCA time (65.9%); Group B: patients with 20% or more immediate post-PTCA time (21.5%). Group C: patients with total obstruction of vessel (12.6%). The basal clinical conditions were similar in the three groups. The degree of basal obstruction and the clinical findings were similar in the three groups; the dilated arteries in Groups A and B were similar and total occlusion before PTCA was more frequent in Group C than in B and A; 30 minutes post PTCA lesions in group A had less residual stenosis than group B (p less than .01) and C (p = NS), this difference increased significantly (p less than .0001) at 24 hours and in the late follow-up. In the follow-up (means 6.4 months) there was total restenosis per lesion in 32.9%. In Group A, there was 8.6%; in Group B, 68.4% (p less than .0001) and in Group B plus C, 80%. Patients with more than 10% obstruction had a greater degree of restenosis (43.9%) than when the initial lesion was less than 10% (23.4%).(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon, Coronary↗
PubMed1989

Comparison of three serological tests for Brucella ovis infection of rams using different antigenic extracts.

The sensitivity and specificity of the complement fixation, gel diffusion and ELISA tests for the diagnosis of Brucella ovis infection of rams have been compared using three different antigenic preparations. The antigens obtained by petroleum ether - chloroform - phenol, or cold saline extractions gave poorer diagnostic results than those obtained by hot saline extraction in all the tests. The best sensitivity was obtained with the ELISA (97.6 per cent) followed by the gel diffusion (96.4 per cent) and complement fixation tests (92.7 per cent). The gel diffusion test detected as positive the two rams negative in the ELISA, while the complement fixation test did not improve the sensitivity of the other tests. Under these conditions all the tests were 100 per cent specific when testing sera from rams free of B ovis.

Animals↗
PubMed1989

Isolation and characterization of a conditional replication mutant of the antibiotic resistance factor R1 affected in the gene of the replication protein repA.

In vitro mutagenesis with hydroxylamine of a ParD- miniderivative of R1, pAB174, yielded mutants that were less stable in the cell than pAB174. Some of these mutants had a thermosensitive phenotype. The replication of pAB2623, one of the thermosensitive mutants, was inhibited in the cell at the restrictive temperature of 42 degrees C. The efficiency of the RepA protein of pAB2623 to promote replication of R1 in an in vitro assay was greatly reduced. Sequence analysis indicated that the repA gene of pAB2623 contains, close to its 3' end, two GC-AT transitions, separated by a single base, that change two consecutive codons of the gene. These results indicate that the phenotype of the mutant is the consequence of a mutated RepA protein and is consistent with the requirement of RepA for the in vivo replication of this plasmid.

Bacterial Proteins↗
PubMed1989

Comparative analyses of proteins extracted by hot saline or released spontaneously into outer membrane blebs from field strains of Brucella ovis and Brucella melitensis.

Sheep infected with Brucella ovis produce antibody responses to the rough lipopolysaccharide and to proteins present in hot saline (HS) extracts of B. ovis (J. I. Riezu-Boj, I. Moriyón, J. M. Blasco, C. M. Marín, and R. Díaz, J. Clin. Microbiol. 23:938-942, 1986). The distribution and antigenic relatedness of proteins in HS extracts and in outer membrane blebs were established by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blotting for 41 strains of B. ovis and 26 strains of Brucella melitensis of diverse geographic origin. Five major groups of proteins were identified in HS extracts of B. ovis that had been freed of rough lipopolysaccharide: proteins of 43 kilodaltons (kDa), group A (25.5 to 32.0 kDa), group B (21.5 to 22.5 kDa); group C (18.0 to 19.5 kDa), and group D (13.0 to 15.5 kDa). Group A, B, C, and D proteins were also present in blebs. The profiles of proteins in HS extracts or blebs from strains of both Brucella species were very similar. Cross-reactions were demonstrated among HS extracts and blebs of all strains tested in immunoblots performed with an antiserum against the HS extract of a reference strain of B. ovis. Evidence was also provided of an antigenic relationship between group 3 proteins of the outer membrane and some of the proteins in groups A, B, and C. The conservation of these antigens and their immunogenicity in infected animals provide promise that they may serve as components of an effective subcellular vaccine for ovine brucellosis.

Animals↗
PubMed1989

[Tobacco consumption in a group of physicians of the V Valparaiso Region (Chile)].

We surveyed 174 physicians from the Valparaiso area regarding smoking habits. 25% were smokers and 75% were not, among them 103 exsmokers (70%). A slightly higher, but not significant percentage of women smokers was observed. Compared to the general population in that area the percentage of physician smokers is significantly lower. The latter show a greater tolerance to smoking habit among their family and patients. Most doctors surveyed were not impressed by the anti-smoking campaigns of health authorities.

Adult↗
PubMed1989

[Paroxysmal nocturnal hemoglobinuria: physiopathology and therapeutic management].

The authors study the pathophysiology and the therapy of patients with paroxysmal nocturnal hemoglobinuria according with the literature reviewed. They also refer to have studied seven cases with HPN, two of which were women and five men, between the ages of 26 and 76 years of age, with symptomatology that varied from moderate, chronic hemolytic anemia and acholuria, to severe pancytopenia with bleeding, infections, and requiring transfusions, antibiotics, corticosteroids, androgens and other supportive measures. Most of them had enlargement of the spleen and liver, especially during hemolytic crises.

Adult↗