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Biomedical subjects

R Diaz

Publications and source records attributed to R Diaz.

At least 127 records · Page 7Linked to original sources
PubMed1984

Reference intervals for serum lipids, lipoproteins, and apoproteins in the elderly.

We measured total cholesterol, high-density-lipoprotein cholesterol, low-density-lipoprotein cholesterol, triglycerides, apoprotein A, and apoprotein B in serum. The subjects were a volunteer group of 145 white people (50 men and 95 women) ranging in age between 65 and 95 years, who were not receiving medical treatment and had no disease that could influence lipid metabolism. Before further categorization, we saw no significant sex-related difference in any of these lipid constituents. The mean age of the group was about 80 years, and we compared results for those older and younger. For the women, the only significant difference was a decrease in low-density-lipoprotein cholesterol for those older than 80 years. In men over 80 there was a significant decrease in triglycerides and in apoprotein B and an increase in high-density-lipoprotein cholesterol. The only sex-related difference for persons under and over 80 was in values for high-density-lipoprotein cholesterol, which were higher for men over 80, whereas triglycerides were higher for women over 80.

Aged↗
PubMed1983

Large V waves in the pulmonary capillary wedge pressure tracing without mitral regurgitation: the influence of the pressure/volume relationship on the V wave size.

We have previously demonstrated that a large V wave in the pulmonary capillary wedge tracing may occur in the absence of mitral regurgitation. This study evaluates the role of left atrial and pulmonary vein compliance on such a finding. We studied 11 patients with coronary disease, without clinical or angiographic mitral regurgitation. Heart rate, pulmonary capillary wedge mean, A and V waves, V-wave slope, left ventricular and aortic pressures, cardiac output, and left atrial echo and apical phonocardiogram were recorded simultaneously. Preload was modified acutely by volume overload and by the administration of i.v. nitroglycerine. Volume administration induced a marked increase in V-wave pressure (13.0 +/- 9.6 vs. 27.0 +/- 9.6 mmHg, p less than 0.05), without producing mitral regurgitation, and without appreciable change in left atrial dimension by echo (33.0 +/- 4.9 vs. 35.5 +/- 5.2 mm, NS), or stroke volume (101.7 +/- 26.2 vs. 97.8 +/- 34.3 ml, NS). An increase was also seen in the A wave (13.6 +/- 8.9 vs. 23.3 +/- 8.5 mmHg, p less than 0.05), pulmonary capillary wedge mean pressure (9.8 +/- 7.2 vs. 20.6 +/- 7.8 mmHg, p less than 0.05), and left ventricular diastolic pressure (7.4 +/- 5.5 vs. 14.6 +/- 6.3 mmHg, p less than 0.05). All values returned to baseline after nitroglycerine. The compliance of the left atrium/pulmonary veins decreased with increasing pulmonary capillary wedge pressures. With large filling volumes, a small stroke volume brings on a large pressure change, thus explaining the finding of large V waves in patients with elevated pulmonary capillary wedge pressure and without mitral regurgitation.

Angina Pectoris↗
PubMed1983

Rapid identification of Serratia marcescens by coagglutination.

All 20 O serotypes of Serratia marcescens produce a common, soluble antigen. Crude antigen was obtained by ammonium sulfate precipitation of spent growth medium, antiserum was produced in rabbits, and a coagglutination test for rapid identification of S. marcescens was developed. A total of 701 clinical isolates of gram-negative bacilli were examined, and a 100% correlation between biochemical identification of S. marcescens and identification by coagglutination was found.

Agglutination Tests↗
PubMed1982

Replication of the broad host range plasmid RSF1010 in cell-free extracts of Escherichia coli and Pseudomonas aeruginosa.

Replication of exogenous RSF1010 DNA can be carried out by soluble enzyme systems from Escherichia coli and Pseudomonas aeruginosa. It requires the function of RSF1010-encoded replication protein(s), which is not expressed in extracts from plasmid-free bacteria. In contrast to previously described in vitro systems for plasmid replication, initiation of RSF1010 DNA synthesis is independent of transcription catalyzed by host RNA polymerase. This is indicated by the insensitivity of RSF1010 replication to rifampicin as well as to RNA polymerase antibodies. It is proposed that a host RNA polymerase transcription-independent initiation mechanism might be a general property of broad host range plasmids.

Anti-Bacterial Agents↗
PubMed1982

Immunological identity of brucella native hapten, polysaccharide B, and yersinia enterocolitica serotype 9 native hapten.

Yersinia enterocolitica serotype 9 contained an antigenic component giving a reaction of total identity with Brucella native hapten and polysaccharide B. This component was present in a phenol-water extract (fraction 5; M. Redfearn, Ph.D. Thesis, University of Wisconsin, Madison, 1960) along with the smooth lipopolysaccharide. The native hapten could be purified free of lipopolysaccharide and proteins by gel filtration.

Antigens, Bacterial↗
PubMed1982

Origin and direction of mini-R1 plasmid DNA replication in cell extracts of Escherichia coli.

Replication of the mini-R1 plasmids pKN177 and pKN182 can be carried out efficiently in cell extracts of Escherichia coli and depends on both transcription and translation. Heteroduplex and restriction analyses indicate that both plasmids are derived from the R1 copy mutant pKN104 by Is1-mediated recombination events without involving structural alterations in the replication region. To ascertain whether the in vitro replication of these miniplasmids corresponds to R1 replication in vivo, the origin and direction of replication were analyzed by electron microscopy of replicative intermediates. It was found that replication starts at a unique origin located within the RepA region at R1 coordinate at 82.4 kilobases and proceeds unidirectionally toward the IS/b sequence. The specification of the origin and the direction of in vitro replication are therefore in full agreement with the pattern observed previously for the in vivo replication of the closely related plasmids R100 and R6-5. This agreement provides additional evidence that R1 DNA synthesis in vitro employs the same replication mechanism as it does in vivo.

Base Sequence↗
PubMed1981

Plasmid R1 DNA replication dependent on protein synthesis in cell-free extracts of E. coli.

Bacterial plasmids serve as model systems for studying the regulation of DNA replication. Elucidation of the molecular mechanisms involved in plasmid DNA synthesis requires the development of efficient cell-free plasmid replication systems. Such in vitro systems have previously only been described for Col E1-type plasmids and for the R6K plasmid. Here we report that extracts of Escherichia coli can carry out the complete replication of miniplasmids derived from the antibiotic-resistance plasmid R1. This R1 replication system differs from the previously described ColE1 and R6K systems in its strict dependence on DNA-directed protein synthesis. We believe this to be the first report of the functional coupling of the three fundamental reactions of genetic information transfer (transcription, translation and replication) in a cell-free system.

Bacterial Proteins↗
PubMed1981

Rac-E. coli K12 strains carry a preferential attachment site for lambda rev.

Lambda rev is a hybrid lambdoid phage formed by recombination between lambda and a defective lambdoid prophage (Rac) present in most E. coli K12 derivatives. We show here that three independently derived Rac-E. coli K12 strains are specifically deleted for the entire Rac prophage consistent with loss of Rac by excisive recombination between hybrid attachment sites that flank the prophage (c.f. excision of a lambda prophage). lambda rev, in which int and PP' of lambda have been replaced by integrative recombination genes and an attachment site derived from Rac (Gottesman et al. 1974), integrates site-specifically and in the correct orientation at the preferential attachment site generated by Rac excision.

Attachment Sites, Microbiological↗
PubMed1981

A simple method for the extraction of polysaccharide B from Brucella cells for use in the radial immunodiffusion test diagnosis of bovine brucellosis.

In order to extract the polysaccharide B of brucella used in Radial Immunodiffusion test (RID) for detection of infected cattle, a quick, simple and safe method is proposed. It consists of using phenol killed cells of B. melitensis 16 M known to produce polysaccharide B. After autoclaving brucella cells resuspended in saline, the cells are separated by centrifugation and the polysaccharide B is obtained by two successive ethanol precipitations of the supernatant. Comparison of the results of RID tests carried out with the polysaccharide extract of B. melitensis 16 M (rapid method) and 231 sera of infected cattle shows the validity of this method of preparation. Differences in yield (1.5% for the second precipitate against 0.5% for the polysaccharide-reference and in optimum dose used the reaction (10 microgram against 200 microgram) show that as many as 60 times more RID tests can be made with the polysaccharide obtained by rapid method.

Animals↗
PubMed1980

Runaway replication of plasmid R1 is not caused by loss of replication inhibitor activity of gene cop.

The replication control functions of a mutant of plasmid R1 that replicates without control at temperatures above 35 degrees C have been analyzed. Although the mutations have not been mapped precisely, the data indicate that the gene (cop) previously identified on the wild-type plasmid (S. Molin and K. Nordström, J. Bacteriol. 141:111-120, 1980) as being responsible for expressing a trans-acting replication inhibitor, as well as for incompatibility of plasmid R1, is not affected in this mutant. Thus, the conditional lack of replication control observed in this plasmid mutant presumably is not caused by the loss of inhibitor activity of the cop gene.

DNA Replication↗
PubMed1980

Nitrates, chlorates and trihalomethanes in swimming pool water.

Water from swimming pools in the Miami area was analyzed for nitrates, chlorates and trihalomethanes. The average concentrations of nitrate and chlorate found in freshwater pools were 8.6 mg/liter and 16 mg/liter respectively, with the highest concentrations being 54.9 mg/liter and 124 mg/liter, respectively. The average concentration of total trihalomethanes found in freshwater pools was 125 micrograms/liter (mainly chloroform) and in saline pools was 657 micrograms/liter (mainly bromoform); the highest concentration was 430 micrograms/liter (freshwater) and 1287 micrograms/liter (saltwater). The possible public health significance of these results is briefly discussed.

Chlorates↗
PubMed1979

Location and characterisation of a new replication origin in the E. coli K12 chromosome.

A segment of DNA located in the region of the E. coli K12 chromosome previously identified by the Rac phenotype can function as a self-replicating plasmid. Evidence is presented that this plasmid, the oriJ plasmid, contains the origin of replication of a defective prophage postulated to be located in this chromosomal region by Low (1973). The plasmid can only be maintained in strains in which this postulated prophage has been deleted. In strains which possess the prophage selection for plasmid maintenance permits the isolation of clones containing new deletions which we postulate are the result of prophage excision.

Chromosome Mapping↗