PubMed Health⌕ Search

Biomedical subjects

R Rivas

Publications and source records attributed to R Rivas.

13 recordsLinked to original sources
PubMed2001

A two primers random amplified polymorphic DNA procedure to obtain polymerase chain reaction fingerprints of bacterial species.

Polymerase chain reation (PCR) fingerprints are used to characterize and recognize bacteria and are generally obtained using universal primers that generate an array of DNA amplicons, which can be separated by electrophoresis. Universal primers 8F and 1491 R have been used to amplify specifically 16S rDNA. We have used these primers at an annealing temperature of 50 degrees C. Agarose gel electrophoresis of PCR products revealed several bands. The band pattern of each bacterial species was different and the strains belonging to the same species shared an identical pattern. The patterns obtained did not show variations with plasmid DNA content or the growth stage of the bacteria. The peculiarity of the randomly amplified polymorphic DNA (RAPD) described in this work lies in the use of two large primers (proximately 20 nt) to obtain the pattern, since normally a only smaller primer is used, and in the new application for the primers used to amplify 16S rDNA. This new procedure, called two primers (TP)-RAPD fingerprinting, is thus rapid, sensitive, reliable, highly reproducible and suitable for experiments with a large number of microorganisms, and can be applied to bacterial taxonomy, ecological studies and for the detection of new bacterial species.

Bacteria↗
PubMed2001

An effective, rapid and simple method for total RNA extraction from bacteria and yeast.

In this work, we describe a rapid and simple method for total RNA extraction from bacteria and yeast. The method allows for the acquirement of high RNA yields while avoiding the use of phenol or other toxic reagents and is less expensive than other methods previously described. The extracted RNA is suitable for applications such as RT-PCR, Northern blot hybridization and low molecular weight RNA (LMW RNA) electrophoresis.

Bacteria↗
PubMed2000

Flow cytometric detection of intracellular myeloperoxidase, CD3 and CD79a. Interaction between monoclonal antibody clones, fluorochromes and sample preparation protocols.

Detection of intracellular myeloperoxidase (MPO), CD79a and CD3 has become the most specific tool for the assignment of myeloid, B- and T-lymphoid lineages in acute leukemias. In order to establish the best combination of monoclonal antibody reagent and sample preparation technique for the intracellular detection of these three markers, we compared six different cell fixation-permeabilization kits (Cytofix/Cytoperm, Fix and Perm, Intraprep, Intrastain, Permeacyte and Permeafix) using 12 fluorochrome conjugates derived from seven monoclonal antibody (mAb) clones. A total of 21 samples corresponding to normal peripheral blood (n=4), normal bone marrow (n=3), acute myeloblastic leukemia (AML, n=6), precursor B-acute lymphoblastic leukemia (ALL, n=6) and T-ALL (n=2) cases, were analysed in two centers. All fixation/permeabilization methods resulted in decreased side scatter and mostly increased forward scatter as compared to erythrocyte-lyse-washed and 1% paraformaldehyde fixed samples. The autofluorescence levels of the leukocyte populations was only significantly increased with use of the Cytofix/Cytoperm kit and mildly with the other techniques. In addition, non-specific staining increased significantly for combinations of any anti-MPO mAb with the Cytofix/Cytoperm kit and for the CD3 clone S4.1 combined with any intracellular method. Anti-MPO antibodies gave a stronger fluorescence signal when conjugated to PE than when coupled to FITC. In conclusion, MPO-7-PE, UCHT-1-PE (CD3) and any HM57-PE conjugate (CD79a) in combination with Fix and Perm, Intraprep, Intrastain or Permeafix, provided specific staining of the respective markers in sufficient intensities. Thus, combined selection of fixation/permeabilization kits and monoclonal antibody reagents against CD3, CD79a and MPO is required for obtaining optimal cytoplasmic detection of these antigens.

Antibodies, Monoclonal↗
PubMed1995

Optical microscopy. 3. Tracking fluorescently labeled neurons in developing brain.

For decades, time-lapse microscopy has been used to track dynamic events associated with biological phenomena. Time-lapse studies of the developing nervous system have been restricted to analysis of dissociated cell cultures or of a series of static images from living organisms. The advent of new fluorescent dyes and video imaging technology has produced novel views of the behavior of neurons in the context of the developing nervous tissue, such as migrations within and away from proliferative zones and navigation of axonal processes to synaptic targets. After fixation of the tissue preparation, time-lapse monitoring can be followed by other analytical techniques and forms of microscopy, e.g., immunocytochemistry or electron microscopy, producing information on the interactions of individual cells whose behavioral histories are known. The power of video time-lapse microscopy of living brain tissue lies in the firsthand documentation of developmental patterning, which in turn can serve as an experimental assay.

Animals↗
PubMed1989

Scleromyxedema and severe myositis.

A case of scleromyxedema with associated rhabdomyolysis is reported. This appears to be a well-documented, although rare complication of scleromyxedema. This case is unique in that mucin was demonstrated in the muscle as well as the skin, and spontaneous resolution of the rhabdomyolysis occurred with the implementation of IV fluids and bed rest.

Adult↗
PubMedDate not supplied

[Arteriosclerosis obliterans. Treatment with angiotensin-converting enzyme inhibitors].

We compare the effects of two of the main angiotensin convertase enzyme inhibitors, captopril and enalapril, aiming to evaluate their effects in the arterial circulation performance, micro-circulation, and changes in regional blood flow, assuming their property of lowering the angiotensin II blood levels, a very strong peripheral vasoconstrictor. We studied 22 patients: all of them with hypertension and/or skin ulcerations, dropping out those who had venous. They were evaluated periodically, clinically and with photoelectric plethysmography of lower extremities. To interpret the traces we designed an ideogram which gathered the plethysmographic behavior before and after the treatment. Nearly 80% showed considerable improvement in pain, functional capacity and plethysmographic traces patterns. healing of the ulcerations was achieved in all case. We propose some hypothesis to explain the good effect that we have observed.

Adult↗