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Biomedical subjects

M A Ruiz

Publications and source records attributed to M A Ruiz.

At least 37 records · Page 2Linked to original sources
PubMed2000

Adsorption of omeprazole on latex particles and characterization of the complex.

Omeprazole is an antisecretory drug used against gastric ulcers. It quickly decomposes in an acid medium, however, therefore making it a matter of great interest to protect it in these conditions and determine the ideal adsorption conditions for this drug on latex particles for formulation designs--oral suspensions--containing polymers with the aim of delivering different drugs in a sustained and controlled action. Time, pH, and concentration of the active ingredient for which maximum adsorption occurs, were determined. The findings suggest that adsorption is evidently greatest at an acid pH 4-5, that the adsorption of Omeprazole rises concomitantly with the increase in latex particles, and the time is the least influential factor.

Adsorption↗
PubMed2000

Adenosine A(1) receptor in cultured neurons from rat cerebral cortex: colocalization with adenosine deaminase.

Adenosine A(1) receptors (A(1)Rs) have been characterized in primary cultures of neurons from cerebral cortex. The specific adenosine A(1) antagonist 8-cyclopentyl-1,3-[(3)H]dipropylxanthine bound to both membranes and intact cells. When saturation experiments were performed in membranes, a K(D) value of 0.76 nM and a B(max) of 57 fmol/mg of protein were obtained. Competition assays revealed a pharmacological profile characteristic of A(1)Rs. The presence of this receptor was further confirmed by RT-PCR analysis. The expression of the receptor showed no significant changes during the period of culture studied, up to 12 days in vitro. A(1)R agonist inhibited forskolin-stimulated adenylyl cyclase, showing the functional coupling of these receptors with the effector. alphaG(i1, 2) protein level, detected by immunoblot, presented an increase during the period of culture. This increase correlated with an increase in the mRNA level of alphaG(i1) but not alphaG(i2). By immunochemical assays, it is shown that these receptors are expressed in both the neuronal cell body and the proximal dendrites. Colocalization of A(1)Rs with microtubule-associated protein 2 and cell surface adenosine deaminase was shown by confocal microscopy. The high degree of colocalization observed between A(1)Rs and ectoadenosine deaminase in neurons could suggest an important role of the enzyme in adenosine-mediated neuromodulation.

Adenosine Deaminase↗
PubMed2000

Adsorption-desorption of ondansetron on latex particles.

Ondansetron is a carbazol with antiemetic properties. It is used primarily to control nausea and vomiting caused by cytotoxic chemotherapy and radiotherapy, as well as for treatment of postoperative vomiting in gynecological surgery. Ondansetron has a shelf life of about 3 hr; hence, it is a matter of great interest to determine the ideal adsorption-desorption conditions for this drug on latex particles for designs of formulations (oral suspensions) containing polymers with the aim of delivering different drugs in a prolonged and controlled fashion. Time, pH, electrolytes, and concentration of the active principal at which maximal adsorption occurred were determined. Desorption of the drug from latex polymer particles was studied in different media. The results obtained suggest that this polymer is suitable as carrier of drug for obtained formulations of controlled release. The findings suggest that pH is the principal factor influencing the release of the ondansetron from Aquateric. The greatest release of drug occurs at acid pH, approximately 70% in the first hour; for the basic medium, the release is about 6%.

Adsorption↗
PubMed2000

Prenatal molecular diagnosis of glutaric aciduria type I by direct mutation analysis.

Various biochemical strategies are followed for the prenatal diagnosis of glutaric aciduria type I (GA I). However, since the description of patients with normal excretion of glutarate and significant residual activity, the difficulties of prenatal biochemical diagnosis are obvious. The characterization of the glutaryl-CoA dehydrogenase (GCDH) gene has allowed us to develop a single strand conformation polymorphism (SSCP) screening method, followed by direct sequencing, to identify the disease causing mutations in patients with GA I. Here we report the first prenatal diagnoses based on DNA analysis in chorionic villi biopsy or cultured amniotic fluid cells in three families at risk for GA I. Our results show that this strategy provides a fast and reliable method for prenatal diagnosis. In addition we report two new mutations (1209-1210ins G and R161W) in the GCDH gene that occurred at hypermutable loci.

Child, Preschool↗
PubMed1999

Formation of ondansetron polymorphs.

We used differential scanning calorimetry, infrared spectrophotometry and 1H nuclear magnetic resonance imaging to search for polymorphs of ondansetron. Samples were tested under different conditions of temperature, pulverization and pH, and in different solvents. The factors identified as able to cause the formation of polymorphs were heating to different temperatures for different times, and the use of ethanol and methanol as solvents.

Antiemetics↗
PubMed1999

Development, formulation, and effectiveness testing of a silicone-based barrier-type hand cream.

We report the development, design, and results of effectiveness and acceptability testing of a hydrating, nutritive, barrier-type hand cream designed for severely damaged skin (including skin damaged by dermatological problems). We tested different silicone derivatives and a water-in-oil (W/O) silicone emulsifier to produce organoleptic qualities that would increase consumer acceptance of this type of W/O emulsion. Pharmacotechnical and effectiveness tests were done to check the stability and preservation of the formulas, their usefulness in improving dry skin, and acceptance by users. The results of pharmacotechnical testing were optimal. Although no active principle aimed specifically at dermatological problems was present in the final formulas, users reported notable subjective improvements in cracking and scaling.

Chemistry, Pharmaceutical↗
PubMed1999

Using the structural analysis of social behavior (SASB) to differentiate young adults with borderline personality disorder features.

The present experiment investigated the ability of the Structural Analysis of Social Behavior (SASB) Intrex questionnaires to differentiate nonclinical samples of young adults with features of either borderline personality disorder (BPD), schizotypal personality disorder (SPD), or no personality disorder (no PD). A number of significant differences were demonstrated on the SASB Intrex questionnaires when comparisons were made between the BPD and no PD samples. These results are consistent with those reported in an earlier investigation of BPD using SASB in a clinical sample. Few differences were found between the SPD features sample and the other two samples. These results are not consistent with previous findings that have differentiated BPD and SPD in clinical samples. The results are discussed in terms of the possible implications for SASB to differentiate BPD, the use of nonclinical samples in personality disorder research, and dimensional models for conceptualizing personality disorders.

Adult↗
PubMed1998

Intravenous calcitriol improves anaemia and reduces the need for erythropoietin in haemodialysis patients.

In cases with severe hyperparathyroidism, anaemia improves after parathyroidectomy. The objective of this study was to investigate the influence of treatment with intravenous calcitriol on anaemia in 28 haemodialysis patients. The patients showed moderate to severe hyperparathyroidism (mean parathyroid hormone level 811.6 +/- 327 pg/ml) and were treated with calcitriol (2 microg i.v.) after haemodialysis. The follow-up period was 12 months. 21 out of the 28 patients had been receiving erythropoietin (EPO) prior to calcitriol administration; the remaining 7 did not receive EPO. 24 patients received oral or intravenous iron. The doses of EPO and iron were modified throughout the study period to maintain a haematocrit equal to or higher than 30% and ferritin levels above 150 ng/ml, respectively. EPO needs were evaluated according to the relation EPO dose/haematocrit. We found a significant rise in haematocrit and haemoglobin at 3 and 12 months on calcitriol therapy, with no modification of the EPO dose nor ferritin levels. This improvement in anaemia was observed both in those patients who received EPO initially (p < 0.01) and in those who did not (p < 0.05). Upon dividing the patients according to the response of hyperparathyroidism to the intravenous calcitriol treatment, we observed in the responding patients (n = 19) significant increases in haematocrit (from 31.7 +/- 4.2 to 36.3 +/- 4.9%) and haemoglobin(from 10.6 +/- 1.5 to 12.2 +/- 1.5 g/dl; p < 0.001) at 12 months on intravenous calcitriol therapy, while this was not true of the non-responding patients. The EPO needs diminished in the group of responding patients and increased in the non-responders, although these changes were not statistically significant. We found no direct correlation between the decrease of parathyroid hormone and EPO needs in the group of responding patients. However, an inverse correlation between parathyroid hormone levels and EPO needs (r = -0.799, p < 0.05) was seen in the group of non-responding patients. Treatment with intravenous calcitriol in patients on haemodialysis controls secondary hyperparathyroidism, improves anaemia, and decreases the need for EPO. Studies including a larger number of patients are necessary to clarify the mechanisms underlying the improvement of anaemia upon control of secondary hyperparathyroidism with intravenous calcitriol treatment and to confirm our findings.

Alkaline Phosphatase↗
PubMed1998

A comparison of three indexes to assess the dimensions of structural analysis of social behavior.

Structural Analysis of Social Behavior (SASB) is an increasingly popular model of interpersonal and intrapsychic interactions that provides a flexible assessment methodology ranging from an observer-based coding system to a modifiable objective self-report questionnaire: the Intrex. Published research using the Intrex has varied in the methods employed to assess the fundamental dimensions of affiliation and autonomy of SASB. In this article, we review the conceptual and computational differences among 3 indexes to assess the SASB dimensions. Empirical comparisons revealed good support for convergent validity but significant differences in distribution characteristics and orthogonality. These results have direct implications for assessment strategies, statistical analyses, and interpretation of both clinical assessments and clinical research. Results are discussed with reference to developing guidelines for assessment and research use of SASB via self-report.

Adult↗
PubMed1997

Micronucleus monitoring to assess human occupational exposure to organochlorides.

Health surveillance for hazardous situations due to chemical exposure, in particular those which are carcinogenic, requires sensitive monitoring tests. Although experimental studies have shown the genotoxic and carcinogenic effect of several organochlorides, the lack of epidemiologic studies prevents their classification as carcinogenic to human beings. In this context, genotoxicity tests of short duration in human cells gain importance. The relation between the clastogenic effects (chromosome breaks) and cancer induction is already known to the scientific literature. The micronucleus test has been proposed as a good indicator of clastogenesis. In the present study, we evaluated, by means of the micronucleus test, 41 workers of a chemical industry in the state of São Paulo, southeast region of Brazil, who had been exposed to a mixture of chlorinated solvents (carbon tetrachloride, perchloroethylene, and hexachlorobenzene) and 28 workers who had not been exposed. Peripheral lymphocytes stimulated by phytohemagglutinin and with cytokinesis blocked by cytochalasin B were used. The results showed that the exposed workers presented a statistically significant higher frequency of micronuclei than the group which had not been exposed.

Adult↗
PubMed1997

Effect of magnesium sulfate administration on subendocardial and subepicardial perfusion.

The objective of this study was to determine the effect of systemic MgSO4 infusion on subendocardial and subepicardial perfusion. Seventeen spontaneously breathing piglets were examined. Myocardial perfusion was measured using radiolabeled microspheres at baseline, 30 and 60 min after either MgSO4 (80 mg/kg) or saline infusion. Blood pressure, heart rate, and cardiac output were also measured at these time intervals. Comparison of the magnesium-induced changes in systemic blood pressure and on subendocardial and subepicardial perfusion at 30 and 60 min with values obtained with saline solution at 30 and 60 min, yielded no statistically significant difference (Tables 1-3). The ratio of subendocardial/subepicardial blood flow and subendocardial and subepicardial coronary vascular resistance at 30 and 60 min revealed no statistically significant differences between the magnesium and the control group (Table 3). There were no statistically significant difference in cardiac output and heart rate during any of the measured periods (Table 2). Our results suggest that the administration of MgSO4 does not alter the ratio of subendocardial/subepicardial blood flow and the ratio of subendocardial/subepicardial coronary vascular resistance.

Animals↗
PubMed1997

Parental representations and dimensions of personality: empirical relations and assessment implications.

Research on the relations between parental representations, personality traits, and psychopathology was discussed with reference to their integration for clinical personality assessment. Empirical results linking parental representations assessed by the Structural Analysis of Social Behavior and the Five-Factor Model of personality traits in a young adult population supported the position that parental representations significantly relate to adult personality. Individuals whose parental representations were generally affiliative described themselves as less prone to emotional distress (lower neuroticism); more interpersonally oriented and experiencing of positive emotions (higher extraversion); more peaceable and trustworthy (higher agreeableness); and more dutiful, resourceful, and dependable (higher conscientiousness). Parental representations colored by autonomy granting and autonomy taking were related to higher levels of openness to experience but lower levels of conscientiousness and extraversion in self-descriptions. Assessment implications and an integrative assessment strategy were presented along with a clinical case example.

Adult↗
PubMed1997

The clinical detection of scleral icterus: observations of multiple examiners.

Sixty-two medical observers at various levels of medical training examined six patients for the presence or absence of scleral icterus in a double-blind survey. At a total serum bilirubin of 42.8 mmol/l (2.5 mg/dl) and 53.0 mmol/l (3.1 mg/dl), 58% (95% confidence interval [CI] 33-80%) and 68% (95% CI 46-85%) of examiners detected the presence of scleral icterus, respectively. Level of training appeared to influence specificity, as 6 of 8 apparent false-positives (total serum bilirubin = 12.0 mmol/l [0.7 mg/dl] and the presence of scleral icterus) were attributable to medical students. Level of training did not appear to influence sensitivity, as 3 of 11 apparent false-negatives (total serum bilirubin = 66.7 mmol/l [3.9 mg/dl] and the absence of detection of scleral icterus) were not attributable to medical students (p = 0.278). Even at the often-quoted estimate of 42.8 mmol/l (2.5 mg/dl) at which at scleral icterus is detected, approximately one-third of medical examiners in our study did not detect scleral icterus.

Adult↗