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Biomedical subjects

R Gonzales

Publications and source records attributed to R Gonzales.

At least 73 records · Page 4Linked to original sources
PubMed1988

Alpha 1-adrenergic receptor stimulated responses.

alpha 1 Receptors have been investigated using a variety of experimental approaches. alpha 1-Receptor stimulation of phosphoinositide (PI) hydrolysis shows differences in agonist efficacy. The potency series and antagonists clearly suggest that alpha 1 receptors are coupled to phosphoinositide hydrolysis. This coupling appears to be mediated by a guanine nucleotide protein coupling the agonist-receptor complex to the phosphoinositide phosphodiesterase. However, certain alpha 1-agonists stimulate phosphoinositide hydrolysis only at very high concentrations that are not sensitive to prazosin antagonism. Other studies on alpha 1-receptor desensitization note discrepancies in coupling to phosphoinositide hydrolysis that are also found when comparing hypertensive (SHR) and normotensive (WKY) rats. Furthermore, molecular studies indicate that the apparent molecular weight of the alpha 1 receptors varies among tissues. These studies suggest heterogeneity in alpha 1 receptors and alpha 1-receptor-mediated responses. This heterogeneity is supported by studies on alpha 1-adrenergic-receptor-mediated decreases in angiotensin II receptors. The response to alpha 1 stimulation is opposite to that found with phorbol esters, which mimic the second messenger response to PI hydrolysis. Thus, these studies suggest that alpha 1-adrenergic receptors are coupled to multiple second messenger responses, one of which is phosphoinositide hydrolysis.

Animals↗
PubMed1987

[Does the antireflux operation promote growth of the kidneys? Apropos of 65 surgically treated children with a minimal follow-up of 4 years].

A study in 65 children followed up over at least 4 years after Cohen's operation evaluated renal growth rate using Eklof and Ringertz method. Analysis showed that: small kidneys with corticopapillary lesions were all atrophied; hypertrophic kidneys remained hypertrophic or were within a normal growth rate range; normal size kidneys never hypertrophied but atrophied in 13.5% of cases; the presence of corticopapillary lesions multiplied the risk of degradation of a normal size kidney by a factor of 5.5. These findings are in concordance with documented data, only Willscher et al finding accelerated renal growth rate after surgical relief of reflux.

Atrophy↗
PubMed1986

5-(2-Cyclohexylideneethyl)-5-ethyl barbituric acid (CHEB): correlation of hypnotic and convulsant properties with alterations of synaptosomal 45Ca2+ influx.

Male ICR mice (20-35 g) were given either 5-(2-cyclohexylideneethyl)-5-ethyl barbituric acid (CHEB) alone (10-15 mg/kg i.p.) or CHEB (25-75 mg/kg i.p.) after a 1 h pretreatment with phenobarbital (75 mg/kg i.p.). CHEB alone (10 mg/kg) produced excitatory behavior but not convulsive seizures. Higher doses (11-15 mg/kg) produced convulsive seizures resulting in death. Pretreatment with phenobarbital prevented seizure activity. Following phenobarbital pretreatment, CHEB in doses of 50 and 75, but not 25 mg/kg, resulted in hypnosis of 53 +/- 16 and 64 +/- 9 min duration, respectively. In vitro, CHEB (10-200 microM) significantly inhibited 'fast-phase' (3 s) K+-stimulated 45Ca2+ uptake into cerebrocortical synaptosomes. CHEB (10 and 100 microM) also significantly increased basal 45Ca2+ uptake. The addition of CHEB (50 and 100 microM) or pentobarbital (100 microM) to striatal synaptosomes inhibited 'fast-phase' K+-stimulated 45Ca2+ uptake and endogenous dopamine release. CHEB (10-200 microM), but not pentobarbital (100 microM), produced a time- and dose-dependent increase in the resting release of endogenous dopamine from striatal synaptosomes. The results of this study show that CHEB possesses hypnotic activity if its lethal convulsant actions are blocked. The hypnotic actions of CHEB appear to correlate with inhibition of voltage-dependent calcium channels in brain synaptosomes.

Animals↗
PubMed1984

Distribution of carnitine and acylcarnitine in the hamster epididymis and in epididymal spermatozoa during maturation.

The highest levels of carnitine and acylcarnitine were found in the cauda epididymidis, and spermatozoa from the cauda contained greater amounts of total carnitine (free carnitine plus acylcarnitine) than those removed from the corpus or caput epididymidis. Spermatozoa from the distal cauda contained significantly greater amounts of both free and total carnitine than those removed from the proximal cauda epididymidis. The acylcarnitine:carnitine ratio was 1.7 and 0.37 in caput and cauda spermatozoa, respectively and 1.7 and 1.3 in caput and cauda fluid, respectively. It is suggested that the accumulation of carnitine is involved in sperm maturation and that acylcarnitine serves as an energy substrate for epididymal spermatozoa.

Acetylcarnitine↗
PubMed1984

Superoxide dismutase, catalase, and glutathione peroxidase in red blood cells from patients with malignant diseases.

Superoxide dismutase (SOD), catalase, and glutathione peroxidase activities have been determined in red blood cells isolated from patients with acute myelogenous leukemia, chronic lymphocytic leukemia, Hodgkin's disease, lymphosarcoma, and various visceral cancers. In all investigated cases, both catalase and glutathione peroxidase were found to be in normal ranges of activity. In the group of patients with visceral cancers, SOD activity was found to be normal as well. In contrast, SOD activity was found to be significantly increased in red blood cells from patients with acute myelogenous leukemia and lymphoproliferative syndromes. This increase in superoxide level was not related to either reticulocytosis or hypochromic anemia. No relationship was found between the SOD level and the stage, the extension of the disease, or the presence of an inflammatory syndrome. The highest SOD levels were observed in untreated patients or during the early time period of the treatment. SOD levels further decrease as a function of the increase in the duration of the treatment. These results suggest an abnormality in the regulation of the expression of the SOD gene in the pluripotent stem cells.

Catalase↗
PubMed1983

Electrophysiologic testing in the management of patients with the Wolff-Parkinson-White syndrome and atrial fibrillation.

Twenty patients with the Wolff-Parkinson-White (WPW) syndrome and 1 or more episodes of symptomatic atrial fibrillation (AF) due to rapid anterograde bypass tract conduction underwent electrophysiologic testing. The mean ventricular rate during spontaneous AF was 242 +/- 56 beats/min (+/- standard deviation) and the shortest preexcited R-R interval was 194 +/- 40 ms. Six patients underwent surgical bypass tract ablation and 14 were treated medically, based on the results of electropharmacologic testing. Over a mean follow-up period of 35 +/- 19 months (+/- standard deviation), only 1 patient treated medically had a recurrence of minimally symptomatic AF. The successful chemoprophylaxis of symptomatic AF was associated with the inability to induce AF and atrioventricular reciprocating tachycardia during drug testing (7 patients) or with the induction of AF with a ventricular rate less than 200 beats/min and a shortest preexcited R-R interval of greater than 250 ms (7 patients). Electrophysiologic testing can identify a subgroup of patients with WPW and AF in whom medical therapy is a suitable alternative to bypass tract ablation.

Adolescent↗
PubMed1982

Wilms' tumor: an approach to vena caval intrusion.

Wilms' tumor invades the renal vein in 12% of patients and extends into the inferior vena cava in another 6%. In a few cases, the tumor propagates into the right side of the heart. Since patients with Wilms' tumor seldom require renal arteriography, and because vena cava involvement may be silent, venous invasion may go undetected until the time of radical nephrectomy. A preoperative vena cavogram is recommended, and if a thrombus is found, a right heart angiogram is needed to determine the superior extent of thrombus. An understanding of the collateral venous circulation of the kidneys and of the physiological effects of malignant or iatrogenic obstruction of the inferior vena cava are essential to formulating the operative approach. Various operative maneuvers, intraoperative studies, and surgical aids (including cardiopulmonary bypass and hypothermia) have made forms of intracaval Wilms' tumor amenable to excision.

Child↗
PubMedDate not supplied

Fast inversion recovery for myelin suppression (FIRMS). A new MRI pulse sequence for highlighting cerebral gray matter.

The purpose of this study is to test a new pulse sequence, fast inversion recovery for myelin suppression (FIRMS) for its ability to improve the conspicuity of gray matter. Twenty-six seizure patients were scanned with FIRMS as well as standard sequences. Gray matter conspicuity was evaluated objectively using region-of-interest calculations, including image contrast, contrast ratios, and contrast:noise (C/N). In evaluation of the hippocampus and cortex, all objective measurements of conspicuity were highest for FIRMS. In five clinical cases of suspected cortical dysplasia, FIRMS improved delineation of pathology in positive cases and ruled out the diagnosis in negative cases. In a case of hippocampal sclerosis, FIRMS was able to demonstrate atrophy of the alveus. Fast inversion recovery for myelin suppression holds promise for its ability to highlight the cerebral cortex and hippocampus.

Cerebral Cortex↗
PubMedDate not supplied

Effective models for medical and health response coordination: summary and action plan.

INTRODUCTION: To effectively respond to this relatively new, complex mandate, it is essential to find effective models of coordination to ensure that medical and health services can meet the standards now expected in a disaster situation. This theme explored various models, noting both the strengths that can be built on and the weaknesses that still need to be overcome. METHODS: Details of the methods used are provided in the preceding paper. The chairs moderated all presentations and produced a summary that was presented to an assembly of all of the delegates. Since the findings from the Theme 1 and Theme 4 groups were similar, the chairs of both groups presided over one workshop that resulted in the generation of a set of Action Plans that then were reported to the collective group of all delegates. RESULTS: The main points developed during the presentations and discussion included: (1) preplanning (predisaster goals), (2) information collection (assessment), (3) communication (materials and methods); and (4) response centres and personnel. There exists a need for institutionalization of processes for learning from experiences obtained from disasters. DISCUSSION: Action plans presented include: (1) creation of an information and data clearinghouse on disaster management, (2) identification of incentives and disincentives for readiness and develop strategies and interventions, and (3) action on lessons learned from evidence-based research and practical experience. CONCLUSIONS: There is an urgent need to proactively establish coordination and management procedures in advance of any crisis. A number of important insights for improvement in coordination and management during disasters emerged.

Data Collection↗
PubMedDate not supplied

Conflicting demands between functional and legal family units.

This article describes a case in which the health-care team initiated treatments assuming that the information provided by the patient was true. Following the onset of complications requiring additional consents and leading to a long-term relationship with family members, there was serious conflict between what was discovered to be a functional family unit and a legal family unit. The patient's wishes were uncertain and not legally supported. After being declared competent for consent, the patient still failed to clearly communicate his wishes to those affected. The case is followed by an ethical analysis.

Aged↗