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Biomedical subjects

R Ibarra

Publications and source records attributed to R Ibarra.

At least 19 recordsLinked to original sources
PubMed1990

Evaluation of the high density lipoprotein cholesterol protective effect against atherogenesis in rabbits fed cholesterol supplemented diets.

Plasma high density lipoprotein cholesterol (HDL-C) was evaluated in 15 rabbits fed cholesterol supplemented diets to assess its protective effect on the atherogenic process. From a baseline level of 29 +/- 11 mg/dl (mean +/- SD) the maximum attained for HDL-C was twofold in only three rabbits, whereas total cholesterol (TC) increased 20 fold. Plasma TC/HDL-C ratio rose 80 fold from the baseline (2.4 +/- 0.9) and it was the best parameter that correlated with aortic cholesterol accumulation and pathological scores. Aortic TC content increased 10 fold and free cholesterol/cholesterol esters ratio decreased 20 fold. Pathological studies showed that aortic lesion scores rose from 0 to 4. It can be concluded that the high correlations obtained when TC/HDL-C ratio was plotted against both aortic cholesterol deposition and lesion scores, support the theory of the reverse cholesterol transport and the effectiveness of this index to predict the degree of the atherogenic process. On the other hand, the poor response of HDL-C in this model encourages future research using drugs to increase this parameter in order to normalize TC/HDL-C ratio and avoid lesions.

Animals↗
PubMed1987

Disposition kinetics of dibekacin in normal subjects and in patients with renal failure.

Dibekacin pharmacokinetics was studied in ten healthy volunteers and six patients with renal failure presenting Clcr less than 10 ml X min-1 per 1.73 m2 of body surface, given as a slow intravenous bolus to the volunteers and as a 30-minute intravenous infusion to the patients. The antibiotic was assayed in plasma and urine by means of a microbiological method using Bacillus subtilis. A two-compartment kinetic model was used to describe the bi-phasic decline of the plasma concentration thus establishing the different pharmacokinetic parameters. Elimination parameters beta, k10 and total body clearance were markedly diminished in renal patients (p less than 0.001): t1/2 beta was 2.0 h, k10 = 0.016 min-1 and Cl = 0.87 ml X min-1 kg body weight in normal subjects and t1/2 beta = 21.4 h, k10 = 0.0011 min-1 and Cl = 0.131 ml X min-1 per kg in the patients. Other kinetic parameters, as distribution (alpha) and transfer (k12, k21) constants were lower in patients than in volunteers. Also the different terms of volume of distribution of the two-compartment model (V1, Vdss, Vdarea) were significantly higher in patients than in normal subjects (p less than 0.05). A good correlation (r = 0.987) between patients' beta constant and creatinine clearance was found. A similar relationship between serum creatinine levels and disposition half-life was found (r = 0.955). Urinary recovery at 24 h was 89.0% of the dose given to normals and 15.8% of the dose given to patients.

Adult↗
PubMed1986

Dream content after using visual inverting prisms.

All night sleep electroencephalograms were recorded in 10 healthy adults for 2 nights. On the second night all subjects were requested to be at the laboratory 5 hr. before their usual bedtime and were submitted to the same routine for performance on several visuomotor tasks; experimental subjects were required to use visual inverting prisms upon their arrival and during the performance of the tasks. Subjects were awakened 10 min. after each paradoxical sleep episode for dream collection. Dream content was significantly affected by the use of the inverting prisms: the presleep tasks and day-time activities were more frequently incorporated into the dreams of the experimental subjects. The dreams of the experimental group were more active and vividness was evaluated as lower by them than by the control subjects.

Adaptation, Psychological↗
PubMed1981

Isolation of liver cells with Ca2+ and K+ chelating agents. Biochemistry and cell morphology.

Cell morphology, glutamic pyruvic (GTP) and glutamic oxalacetic transaminases (GOT) concentrations, and the ability to produce glucose or urea from different substrates (pyruvate, alanine, fructose, lactate and glutamine) were studied in isolated mouse and rat liver cells in the presence of Ca2+ and K+ chelating agents (0.1 M sodium perchlorate and 0.027 M sodium citrate with 1 mg/ml bovine albumin; ionic strength: 0.198, pH: 7.4). The chelating agent is perfused through the portal vein of an in situ liver, at low pressure (8 ml/min) at 20 C for 15 min. Cell dispersion is obtained by cutting liver lobes and "massaging" the tissue with a plastic spatula. Wash and cell concentration may be obtained by sedimentation or centrifugation in Krebs III, glucose 150 mg %, improved with 0.16 M pyruvate, 0.1 M fumarate and 0.16 M glutamate. This procedure furnished 53.06 +/- 3.33 X 10(6) cells, which was highly significant (p less than 0.001) with respect to saline controls: 6.11 +/- 1.91 X 10(6). After staining with Papanicolaou, hematoxylin-eosin, and PAS, the cellular material obtained was classified optically into: normal isolated parenchymal liver cells, hepatocyte clumps, "burst" cells, normal blood or reticuloendothelial cells, cellular debris and non-cellular material. Cell morphology showed that a constant perfusion (8 ml/min) with a minimal mechanical treatment, 82.5% of the liver cells appears normal. Biochemical study showed that transaminases are indeed lost, but this loss is below the amount capable of effecting metabolic blockade (3/4 of transaminases remain in liver cells; GOT in cells: 692 +/- 218; GPT in cells. 264 +/- 94; GOT in supernatant: 152 +/- 29; GPT in supernatant: 79 +/- 12 mUI/10(6) cells, after recovering 60 min at 37 C) (means +/- SEM). Conversion of substrates (sodium pyruvate 10 mM, 20 mM D-L alanine, 10 mM fructose and 20 mM D-L sodium lactate) into glucose was statistically significant with respect to the baseline when the liver cells were isolated and recovered (rat liver cells, basal: 25.37 +/- 3.73; pyruvate: 54.04 +/- 7.98; DL-alanine: 62 +/- 10.07; fructose: 264.67 +/- 20.51; DL-lactate: 78.05 +/- 17.99 mmoles/10(6) cels, means +/- SEM). Urea production from 5 mM DL-glutamine was statistically highly significant to the basal with rat liver cell isolated and recovered (basal: 160.60 +/- 3.76; DL-glutamine: 608.47 +/- 16.15 mmoles/10(6) cells; means +/- SEM). The results obtained suggest that liver cells isolated with Ca2+ and K+ chelating agents used as described above are of value for biochemical studies.

Alanine Transaminase↗