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Biomedical subjects

O González

Publications and source records attributed to O González.

At least 19 recordsLinked to original sources
PubMed1997

Chronic intraventricular infusion with NGF improves LTP in old cognitively-impaired rats.

Aged (21 months) cognitively-impaired male Sprague-Dawley rats received intraventricular infusion of nerve growth factor (NGF) or cytochrome C (Cit C) for 14 or 28 days using miniosmotic pumps and were evaluated either 1 week or 3 months after treatment. Groups of untreated young, aged-impaired and aged non-impaired rats were also evaluated. Under narcose recording and stimulating electrodes were stereotactically implanted in the dentate gyrus and the perforant path. The stimulation intensity was individually adjusted to obtain a half-maximal population spike (P) for test stimuli and a quarter-maximal for tetanization. The amplitude and latency of P and the slope (S) of the field EPSP were determined before and at 2, 5, 15, 30 and 60 min after tetanization at 400 Hz. Paired stimuli at 30 ms interval were also applied before and after tetanization. Aged, cognitively impaired rats showed an absent S potentiation and a delayed P potentiation, both in amplitude and latency, while non-impaired rats behaved like the young controls. Paired pulse inhibition showed no difference among groups before or after tetanization suggesting that the impaired potentiation is not due to an increased retroactive inhibition. NGF treatment ameliorates LTP deficits to levels equivalent to non-impaired rats, while Cit C controls showed no improvement. No differences appear among NGF treated groups, but evidence suggest that the animals evaluated 3 months after treatment developed a stronger potentiation.

Aging↗
PubMed1997

Comparative effects of beta2-adrenergic agonists on muscle waste associated with tumour growth.

The implantation of the Yoshida AH-130 ascites hepatoma (a fast growing tumour) to rats resulted in a dramatic loss of both white adipose tissue and muscle (skeletal and cardiac) mass. Administration of beta2-adrenergic agonists to tumour-bearing rats resulted in a partial recovery of skeletal muscle and heart mass. Treatment of the tumour-bearing animals with the different drugs (salbutamol, salmeterol and clenbuterol) did not influence tumour growth or food intake so it can be suggested that the effects were solely due to metabolic changes. In addition, while the three drugs had clear effects on gastrocnemius muscles, clenbuterol and salbutamol had also an effect on soleus, and salbutamol had a clear effect on cardiac muscle. It is suggested that any of the studied beta2-adrenergic agonists (but perhaps, particularly salmeterol) could be used clinically in the treatment of cancer cachexia.

Adipose Tissue↗
PubMed1996

Effect of size, concentration, surface area, and volume of polymethylmethacrylate particles on human macrophages in vitro.

This study investigated effects of different sizes, concentrations, volumes, and surface areas of polymethylmethacrylate (PMMA) particles on human macrophages. Adherent peripheral blood monocytes isolated from five healthy individuals were exposed for 48 h to phagocytosable (0.325 micron and 5.5 microns) and nonphagocytosable (200 microns) spherical particles. Each particle size was tested over a range of concentrations (10(4)-10(11) particles per milliliter [0.325 micron], 10(2)-10(7) particles per milliliter [5.5 microns], 10(1)-10(4) particles per milliliter [200 microns]) to provide overlap in number, volume, and surface area. Primary human monocyte/macrophages were cultured in macrophage serum-free medium and 5% fetal calf serum. Macrophage viability was assessed by 3H-thymidine uptake and activation was quantified by release of interleukin-1 beta, interleukin-6, tumor necrosis factor-alpha, prostaglandin E2 (PGE2), and the lysosomal enzyme hexosaminidase. Medium alone served as a negative control; lipopolysaccharide (10 micrograms/mL) was also tested. PMMA particles were not toxic to human macrophages at any concentration tested. The smallest phagocytosable particles (0.325 micron) stimulated the release of interleukin-1 beta, interleukin-6, prostaglandin E2, and hexosaminidase at concentrations of 10(10)-10(11) particles/mL. The release of cytokines, PGE2, and hexosaminidase depended on the size, concentration, surface area, and volume of the phagocytosable particles. This study demonstrates that PMMA particle load Mi.e., the concentration of phagocytosable particles per tissue volume, characterized by size, surface area, and volume, rather than simply particle number-determines the degree of macrophage activation.

Cell Survival↗
PubMed1996

Papillary thyroid carcinoma in Mexican patients: clinical aspects and prognostic factors.

The present study characterizes papillary thyroid carcinoma (PTC) in a Mexican patient sample and evaluates potential prognostic factors for recurrence. Clinical records of 229 patients with PTC were analyzed. Surgical specimens were rereviewed and DNA ploidy determined. Cox logistic regression was used to explore prognostic factors. Mean age +/- SD of the patients was 42 +/- 16 years, with a male/female ratio of 24:205. A thyroid mass was the initial manifestation in 99%. Extrathyroid invasion occurred in 45% and nodal metastases in 38%. Mean size +/- SD of the tumors was 3 +/- 2 cm. By flow cytometry 88% of the tumors were DNA euploid and 12% aneuploid. Complete tumor resection was achieved in 83% with an operative mortality of 0.4%. Postoperative hormone suppression was administered in 65% and remnant 131I thyroid ablation in 84%. The 10-year recurrence-free survival was 85%. In the group of patients with tumors totally removed and without distant metastases, none of the 14 evaluated variables demonstrated statistical significance as an independent prognostic factor for recurrence. However, the group of patients in whom a combination of the following factors was present--age > or = 40 years, tumor size > or = 3 cm, local invasion, and lymph node metastases--showed a higher incidence of tumor recurrence.

Adult↗
PubMed1996

Leg stiffness and stride frequency in human running.

When humans and other mammals run, the body's complex system of muscle, tendon and ligament springs behaves like a single linear spring ('leg spring'). A simple spring-mass model, consisting of a single linear leg spring and a mass equivalent to the animal's mass, has been shown to describe the mechanics of running remarkably well. Force platform measurements from running animals, including humans, have shown that the stiffness of the leg spring remains nearly the same at all speeds and that the spring-mass system is adjusted for higher speeds by increasing the angle swept by the leg spring. The goal of the present study is to determine the relative importance of changes to the leg spring stiffness and the angle swept by the leg spring when humans alter their stride frequency at a given running speed. Human subjects ran on treadmill-mounted force platform at 2.5ms-1 while using a range of stride frequencies from 26% below to 36% above the preferred stride frequency. Force platform measurements revealed that the stiffness of the leg spring increased by 2.3-fold from 7.0 to 16.3 kNm-1 between the lowest and highest stride frequencies. The angle swept by the leg spring decreased at higher stride frequencies, partially offsetting the effect of the increased leg spring stiffness on the mechanical behavior of the spring-mass system. We conclude that the most important adjustment to the body's spring system to accommodate higher stride frequencies is that leg spring becomes stiffer.

Adaptation, Physiological↗
PubMed1996

Changes in renal function in primary hypothyroidism.

Renal function impairment and electrolyte disorders in hypothyroidism are frequently subtle and rarely observed in clinical practice. To assess the extent of these defects, serum concentration of electrolytes and glomerular filtration rate were estimated before and after thyroid replacement therapy in 41 patients with primary hypothyroidism. All patients had decreased glomerular filtration rates and 22 patients had increased serum creatinine levels. Although a relationship between creatinine clearance and serum thyrothropin-stimulating hormone was not found, a weak correlation between age and serum creatinine concentration was observed. Hyponatremia was documented in 45% of 22 patients with elevated serum creatinine but in only 21% of 19 patients with normal creatinine. All these defects were corrected by treatment with thyroid hormone. We conclude that creatinine clearance was slightly decreased in all patients with hypothyroidism, this decrease being more noticeable in elderly patients. The greater the impairment in renal function, the more common was the occurrence of hyponatremia.

Creatinine↗
PubMed1996

Narrow-mouthed water storage vessels and in situ chlorination in a Bolivian community: a simple method to improve drinking water quality.

Epidemiologic investigations of the Latin America cholera epidemic have repeatedly implicated untreated drinking water and water touched by hands during storage as important vehicles for disease transmission. To prevent such transmission, we provided a new narrow-mouthed, plastic, water storage vessel and 5% calcium hypochlorite solution for home disinfection of stored water to a Bolivian Aymara Indian community at risk for cholera. We evaluated acceptance of this intervention and its effect on water quality. Each of 42 families in the study obtained water from a household well; fecal coliform bacteria were found in water from 39 (93%) of 42 wells and 33 (79%) of 42 usual water storage vessels. One group of families received the special vessels and chlorine (group A), a second received only the special vessels (group B), and a third served as a control group (group C). Water samples collected every three weeks from group A special vessels had lower geometric mean fecal coliform colony counts (P < 0.0001) and lower geometric mean Escherichia coli colony counts (P < 0.0001) than water from group B or C vessels. Adequate levels of free chlorine persisted in these vessels for at least 5 hr. The special vessels and chlorine solution were well accepted and continued to be used for at least six months. Use of the vessel and chlorine solution produced drinking water from nonpotable sources that met World Health Organization standards for microbiologic quality.

Adolescent↗
PubMed1995

Tolerance of intravitreous interleukin-1 beta in the treatment of experimental vitreous hemorrhage.

We investigated the tolerance of human recombinant interleukin-1 beta (IL-1 beta) injected intravitreously and its putative role in the clearance of experimental vitreous hemorrhages. Three groups of 10 pigmented rabbits each were injected intravitreously with 0.1 ml autologous whole blood. Mean fundus revisualization times after blood clouding were as follows: group 1 (controls, blood injection only), 5.3 weeks; group 2 (100 units of IL-1 beta injected intravitreously 7 days after blood injection), 3.3 weeks; group 3 (1,000 units of IL-1 beta injected intravitreously 7 days after blood injection), 3.2 weeks. Group 4 (10 rabbits) was injected only with 1,000 units of IL-1 beta. Clinical examinations showed a transient mild inflammatory reaction in group 2 and a transient severe reaction in groups 3 and 4. Vitreous opacities, a whitish retinal reaction and vascular changes were seen in group 4. Electroretinography did not show a b-wave decrease in any group. These results suggest that low concentrations of IL-1 beta may be useful for nonsurgical treatment of human vitreous hemorrhage.

Animals↗
PubMed1995

Fluconazole treatment of candida peritonitis with delayed removal of the peritoneal dialysis catheter.

Candida peritonitis was treated with fluconazole in ten continuous ambulatory peritoneal dialysis (CAPD) patients without immediate removal of the peritoneal catheter. Shortly prior to diagnosis, six patients (60%) had received broad-spectrum antibiotics. Gram stain of peritoneal fluid detected yeast in 70% of cases. In eight patients the peritoneal dialysis catheter was removed within one week of diagnosis because of clinical deterioration. In the majority of cases (90%), candida peritonitis resolved only after catheter removal in spite of ongoing fluconazole therapy. Fluconazole was well tolerated by all patients.

Antifungal Agents↗
PubMed1995

[Medical evaluation of the climacteric patient].

A pilot program with primary care physicians was established in Clinica Cuauhtémoc y Famosa, focused to evaluate women older than 35 years with climateric symptoms. This program included a survey, a complete gynecological examination with Pap smears, ultrasound pelvic examination and mamography. Also, blood samples were collected for cholesterol, tryglycerides, calcium, phosphorus and alkaline phosphatase. An ECG, bone densitometry of the radius and X-rays of the vertebral column were obtained. This group was formed by 69 women with an age media of 50 years (SD 7.6 years, median 49 years). The survey disclosed that 34/65 women had been hysterectomized, and only 34/64 had received antitetanic immunization in the last 10 years. A preexistent chronic disease occurred in 36/59 women, these were diabetes mellitus, arterial hypertension or degenerative osteoarthritis. Alcohol consumption was recorded in 5/66 women and tabac consumption in 9/66 women, and 32/68 women accepted to be sedentary. Laboratory examinations disclosed hypercholesterolemia in 19/66 women and hypertryglyceridemia in 8/64 women. Osteopenia was detected in 33/60 women. This findings support a systematic plan to provide medical assistance for women in this age, specially if previous epidemiologycal studies have disclosed that coronary disease is the main cause of death for women older than 50 years in this region, that also belongs to the area of highest incidence of diabetes.

Alcohol Drinking↗
PubMed1994

High flow peritoneal dialysis.

We have developed a catheter extension/continuous ambulatory peritoneal dialysis (CAPD) set (ANDY high flow set) of larger lumen (minimum internal diameter 3.25 mm), and compared peritoneal dialysate flow rates in two groups of 6 stable CAPD patients of comparable age, sex distribution, and time on dialysis according to type of catheter. Both groups were studied with two different extension/sets, standard ANDY and ANDY high flow set. The shortest infusion time was observed with the combination Cruz catheter/ANDY high flow set. The switch to a high flow set decreased significantly the inflow time of both types of catheter, and the infusion time of the Tenckhoff catheter/ANDY high flow combination approximated that of the Cruz/ANDY combination. Likewise, the dialysate outflow rates were highest with the Cruz catheter/ANDY high flow set than with any other catheter/set combination (p = 0.005). This was apparent, not only in the total outflow time, but also in the vol/min during the first 4 min (p = 0.005). None of the patients experienced discomfort during the dialysis exchanges with the high flow system. This combination of Cruz catheter/high flow set effectively reduces the dialysis exchange time and is very much appreciated by the patients.

Catheters, Indwelling↗
PubMed1993

The pig as an animal model for experimentation on the temporomandibular articular complex.

A macroscopic study of the so-called temporomandibular joint of omnivorous mammals (pigs), carnivores (dogs and cats), rodents (rabbits and rats), and herbivores (cows, sheep, and goats) revealed the existence of two left and right temporomandibular articular complexes, each made up of a condylomeniscal and a meniscotemporal joint on either side, as in human beings. In all cases there is a combination of a condylar joint and a reciprocally fitting one. We conclude that the pig is the experimental animal model that most closely resembles human beings for the study of the cited articular structures.

Animals↗
PubMed1993

[Importance of prolactin isoforms on ovary function in hyperprolactinemic women].

Gel filtration chromatography in Sephadex G-100, was used to analyse the molecular heterogeneity of prolactin (PRL) in serum from seven hyperprolactinemic women. Chromatographic patterns from samples obtained from four women with hyperprolactinemia and normal menstrual cycles showed a predominance of big-big PRL (79%). In contrast, three women with hyperprolactinemia and amenorrhea presented a chromatographic pattern with predominance of little PRL (69%). The results suggest that the molecular heterogeneity of PRL found is associated with menstrual cycles disorders and hence with ovarian function. Normal ovarian function in hyperprolactinemic patients seems to be associated to increased levels of big-big PRL and altered ovarian function to high level of little PRL.

Amenorrhea↗
PubMed1989

Effect of bean intake on biliary lipid secretion and on hepatic cholesterol metabolism in the rat.

We studied the effect of a bean diet on biliary lipid secretion, serum cholesterol concentration, and hepatic cholesterol metabolism in the rat. Rats fed a bean diet for 10-12 days had increased biliary cholesterol output and molar percentage by 300% and 200%, respectively, compared to rats fed an isocaloric and isoprotein casein diet. Biliary phospholipid output increased 180%. Bile flow and biliary bile salt output remained in the normal range. Total serum and VLDL cholesterol concentration significantly decreased 27% and 50%, respectively, in the rats fed the bean diet. Hepatic cholesterogenesis was increased 170% in the bean-fed animals. The relative contribution of newly synthesized hepatic cholesterol to total biliary cholesterol increased 200%, and that of endogenous origin only 50%. These results suggested that newly synthesized hepatic cholesterol was preferentially channelled to the biliary cholesterol secretory pathway in bean-fed rats. Although hepatic cholesteryl ester concentration increased 240%, the incorporation of [14C]oleate into hepatic cholesteryl esters was significantly decreased by 30% in isolated hepatocytes of bean-fed animals. These results were consistent with the possibility that the availability of hepatic free cholesterol for biliary secretion was increased in the bean-fed animals. This study demonstrates that bean intake has a profound effect on the metabolic channelling and compartmentalization of hepatic cholesterol, resulting in a significant decrease in total serum and very low density lipoprotein cholesterol concentrations and a high biliary cholesterol output.

Animals↗
PubMed1988

Ten years of selective shunts for hemorrhagic portal hypertension.

Selective portosystemic shunts have been performed in our hospital since 1973 for the treatment of variceal bleeding secondary to portal hypertension. We report our experience in 139 selective operations performed in a 10-year period (1973 to 1983). One hundred thirty patients underwent elective nine underwent emergency surgery. Eighty-five patients were classified in the A functional group of Child, 42 in group B, and 12 in group C. The overall mortality rate in the emergency group was 44% and in the elective group, 13%. Ascitis and transitory hepatic failure were the most common postoperative complications. The long-term follow-up clinical encephalopathy rate was 16%. The survival rate according to the Kaplan-Meier survival analysis was 80% at 2 years, 68% at 5 years, and 67% at 10 years.

Adolescent↗