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Biomedical subjects

M Ruiz

Publications and source records attributed to M Ruiz.

At least 163 records · Page 9Linked to original sources
PubMed1995

Myocardial technetium-99m-teboroxime uptake during adenosine-induced hyperemia in dogs with either a critical or mild coronary stenosis: comparison to thallium-201 and regional blood flow.

UNLABELLED: Experimental studies have shown 99mTc-teboroxime to have a higher first-pass myocardial extraction, exceeding that of 201Tl with nearly linear initial myocardial uptake over a wide range of coronary flows. The goal of this study was to quantitatively compare teboroxime with 201Tl for the assessment of a regional coronary flow imbalance when administered during adenosine vasodilation in dogs with either critical or mild LAD stenoses. METHODS: Twenty-four anesthetized dogs with either critical (n = 10) or mild (n = 14) LAD stenoses were given an i.v. infusion of adenosine (300 micrograms/kg/min). When LCx flow was maximal, 201Tl, teboroxime and microspheres were simultaneously injected and the dogs were killed either 2 or 4 min later. Regional 201Tl, teboroxime activities and myocardial blood flow were determined by gamma well counting and ex vivo imaging of 99mTc-teboroxime activity in myocardial heart slices was performed. RESULTS: In both the critical and mild stenosis groups, the LAD/LCx zone ratios in dogs killed 2 min after tracer injection for both 201Tl (0.31 +/- 0.07, 0.63 +/- 0.05) and teboroxime (0.38 +/- 0.09, 0.72 +/- 0.04) significantly underestimated the microsphere flow ratio (0.18 +/- 0.05, 0.43 +/- 0.05) (p < or = 0.01), but the degree of underestimation was greater for teboroxime compared with Tl (p < or = 0.05). CONCLUSION: In dogs with either critical or mild LAD stenoses, as early as 2 min after tracer injection, the 201Tl activity ratio more accurately assessed the adenosine-induced regional flow heterogeneity than did teboroxime. These results highlight the importance of an ultra-fast imaging protocol when using teboroxime with pharmacologic stress.

Adenosine↗
PubMed1995

Characterization of the lung cancer epidemic in the European Union (1970-1990).

To characterize the situation of the lung cancer epidemic in the former European Community countries, we analyzed mortality time trends between 1970 and 1990, and by using Poisson log-linear models, we compared patterns of evolution between Mediterranean and non-Mediterranean countries. To ascertain the course traced by the cohort effect and the inflection points marking shifts in trend in the epidemic, we made use of invariant parameters from age-period-cohort models (net drift, curvature) and restricted slope range for cohort effect. Regarding men, whereas non-Mediterranean countries had already initiated the downward phase of the process, the Mediterranean countries, with the single exception of Italy, proved to be entirely in the development stage. Women evinced a different pattern of evolution in regard to both rate magnitudes and trend behavior. Apart from Spain and Greece, a sharp rise in adjusted and specific rates was observed for all countries.

Adult↗
PubMed1995

[Low density lipoprotein rich in triglycerides and hepatic lipase activity in insulin-dependent diabetic patients].

Genetic hepatic lipase (HL) deficiency is associated with low density lipoprotein (LDL) rich in triglycerides (TG), whose affinity for B:E receptors is decreased. In rats, experimental hypoinsulinemia produces HL deficiency. However, the relation between human insulin-dependent Diabetes Mellitus (IDDM), HL activity and the characteristics of LDL have not been studied. The objective of our study is to evaluate the relation between HL activity and the chemical composition of LDL in treated IDDM patients. Subjects were 15 IDDM patients and 15 controls (C), matched for sex and body mass index (BMI). The IDDM patients were classified by the WHO criteria, were free of nephropathy and hypothyroidism, and received no medication except insulin. Controls were clinically healthy and normolipidemic with no family history of diabetes. The IDDM group was divided into two subgroups: subgroup IDDM-A (n = 9) with HL values > or = 4.3 and IDDM-B (n = 6) with HL < or = than 4.2 mumoles glycerol/ml h. the HL in IDDM was lower than in C (p < 0.001). Table 1 shows clinical data. Blood samples were drawn after 12 h fasting. Percentage of HbA1c and plasma concentrations of glucose, total cholesterol, LDL-cholesterol, HDL-cholesterol and TG were assayed. LDL was separated by sequential ultracentrifugation at densities of 1.019-1.063 g/ml and its chemical composition was analyzed. The most relevant results were: plasma TG concentration was higher in IDDM than in C (p < 0.05) (Table 2), although average values DMID not exceed the reference values of 200 mg/dl. The TG-LDL were higher in IDDM than in C: 24.8 +/- 2.7 vs 17.5 +/- 1.1 mg/dl plasma, media +/- SE, (p < 0.02). This difference reflected the values of IDDM-B, whose plasma concentrations of TG-LDL were higher than in C: 32.3 +/- 3.6 vs 17.5 +/- 1.1 mg/dl (p < 0.001), and also higher than in IDDM-A (p < 0.02). (Table 3). The chemical composition of LDL in IDDM-B contained a higher percentage of TG than C: 8.5 +/- 0.7 vs 6.8 +/- 0.3% (p < 0.05), a lower percentage of cholesterol than IDDM-A: 39.0 +/- 1.7 vs 45.2 +/- 2.2% (p < 0.05) and also a larger percentage of proteins than IDDM-A: 28.9 +/- 1.9 vs 20.8 +/- 1.0% (p < 0.01). The correlations between TG/cholesterol and HL activity in IDDM were r = -0.53 (p < 0.05) and in IDDM-B, r = -0.81 (p = 0.05). The noteworthy result of this study is the modification of the LDL particle in IDDM, rich in TG in patients with low HL activity. Anomalies in the chemical composition of LDL like those described decrease the uptake of this particle by its physiological B:E receptors. It has recently been demonstrated that LDL is an indisoluble association of lipids and apoproteins, and that both act simultaneously to hold the apoB in a spatial position that expresses normal epitopes. It has been described that particles of LDL rich in TG and poor in cholesterol, shows low affinity for LDL receptors in human fibroblasts. Also in IDDM the interaction of LDL rich in TG with B:E receptors is decreased. This might be one more mechanism contributing to the accelerated atherosclerosis of these patients. Our results suggest that there may be a threshold of HL activity for the complete hydrolysis of the TG of LDL, for the normalization of the TG/cholesterol relation and for the conformation of typical LDL particles.

Adult↗
PubMed1994

Action of sodium fluoride on phagocytosis by systemic polymorphonuclear leucocytes.

Alterations in phagocytosis appear to be important in the onset and development of periodontitis. We investigated new substances that may be of use in the treatment of periodontitis. In a preliminary study, we tested the effect of sodium fluoride on phagocytosis by circulating polymorphonuclear leucocytes (PMNs) in 10 replicate assays using blood from six healthy subjects. Sodium fluoride was tested at concentrations of 1.0 micron to 4.0 microns against Streptococcus oralis, Streptococcus mutans, Streptococcus sobrinus and Streptococcus sanguis. The phagocytic index against all microorganisms increased significantly at all concentrations of sodium fluoride assayed; this effect was dose dependent. Sodium fluoride appeared to stimulate phagocytosis via two mechanisms: an apparent increase in bacterial susceptibility to phagocytosis, and direct stimulation of phagocytosis by PMNs.

Adult↗
PubMed1994

Splanchnic and systemic hemodynamics in early abstinence and after ethanol administration in non-cirrhotic alcoholic patients.

Thirteen asymptomatic chronic alcoholic patients were studied to investigate the early stages of portal hypertension in alcoholic liver disease and the effects of withdrawal and ethanol on hepatic function and hemodynamic variables. None of the patients presented clinical signs of decompensated liver disease, and their liver biopsies showed normal liver or moderate alterations only. In basal conditions and after an intravenous ethanol infusion (1 g/kg body weight), hepatic venous pressure gradient and hepatic blood flow using indocyanine green were measured through hepatic vein catheterization. Hepatic sinusoidal vascular resistance and indocyanine green intrinsic clearance were also calculated. Portal blood flow measurements were obtained by Doppler ultrasound. No correlation was observed between hepatic venous pressure gradient and histologic features, (steatosis, necrosis, fibrosis, inflammation and hepatocyte surface area). In basal conditions, portal hypertension was not found in any case. After ethanol, portal pressure increased significantly (p < 0.001); in four cases it rose to or above 5 mmHg. Portal blood flow, hepatic blood flow and hepatic vascular resistance also increased significantly. Intrinsic indocyanine green clearance decreased slightly but significantly. No significant correlations were found between portal pressure, hepatic resistance and the histologic parameters. It was concluded that alcoholic patients, without clinical or laboratory evidence of liver failure and with minimal or moderate histologic alterations, have normal portal pressures. After an intravenous ethanol load, however, four out of 13 patients (31%) reached levels of 5 mmHg or more, irrespective of their liver histology.

Adult↗
PubMed1994

Epicutaneous test in carbamazepine cutaneous reactions.

Carbamazepine is a widely used drug associated with numerous side effects including skin eruptions that appear in about 4% of patients. Epicutaneous tests have been used with variable success in skin drug reactions. The purpose of this study was to work out the efficacy of this type of test in carbamazepine reactions. Five patients with carbamazepine cutaneous reaction were studied. Clinical, laboratory and histopathological data were recorded. The 5 patients and 20 controls were tested with carbamazepine 1% in petrolatum. In 4 patients the carbamazepine epicutaneous test was positive. The 20 healthy controls were negative. Epicutaneous testing is a simple and helpful method in detecting carbamazepine hypersensitivity.

Adult↗
PubMed1994

Redistribution of 99mTc-sestamibi and 201Tl in the presence of a severe coronary artery stenosis.

BACKGROUND: 99mTc-labeled methoxyisobutyl isonitrile (99mTc-sestamibi) is a myocardial perfusion agent that clears slowly from the myocardium. This study evaluates the early and late myocardial distributions of 99mTc-sestamibi and 201Tl in the presence of low-flow ischemia to determine whether 99mTc-sestamibi demonstrates rest "redistribution." METHODS AND RESULTS: Low-flow ischemia was produced in 18 anesthetized, open-chest dogs by partial occlusion of the left anterior descending coronary artery. Dogs were injected intravenously with 99mTc-sestamibi, 301Tl, and radiolabeled microspheres during sustained low-flow ischemia. The hearts were excised either 20 minutes (group 1, 10 dogs) or 2.5 hours (group 2, 8 dogs) after injection for gamma well counting to evaluate the early and late myocardial distributions of these radiotracers, relative to microsphere flow. The early myocardial distributions of 99mTc-sestamibi and 201Tl were comparable and correlated with the flow deficit (group 1). We observed a significant difference in myocardial 201Tl (P = .005) and 99mTc-sestamibi (P < .0001) activities between groups 1 and 2 dogs relative to flow, suggesting some redistribution of both tracers. Myocardial slices were imaged postmortem with a gamma camera, and 99mTc-sestamibi defect intensity was quantified. There was excellent correlation (r = .97) between the early relative 99mTc-sestamibi defect intensity on postmortem images and the flow deficit (group 1). Among group 2 dogs, the correlation was good (r = .87), but the 99mTc-sestamibi defect was less severe than the flow deficit, again suggesting redistribution. CONCLUSIONS: The myocardial distributions of 99mTc-sestamibi and 201Tl early after injection are comparable and proportional to flow. Under conditions of sustained low flow, there was detectable rest "redistribution" of 99mTc-sestamibi verified by both gamma well counting and high-resolution postmortem imaging of myocardial slices. Whether this degree of 99mTc-sestamibi rest redistribution will be detectable by serial clinical imaging remains uncertain. Nevertheless, these data suggest that imaging should be delayed after the resting injection of 99mTc-sestamibi when assessing myocardial viability in the presence of a critical stenosis.

Animals↗
PubMed1994

[Cystic hygroma. Antenatal diagnosis and clinical management].

Nine cases of cystic hygroma in pregnancy diagnostic by ultrasound are presented. Chromosomal abnormalities accompany in 7 cases occurred, with, great frequency of "Turner Syndrome". The prognostic of this congenital malformation, has relation with the chromosomopaty and the difference between septal and nonseptated cystic hygroma.

Adolescent↗
PubMed1994

Cloning, expression, and localization of a mouse retinal gamma-aminobutyric acid transporter.

PURPOSE: To isolate a cDNA clone encoding a high-affinity gamma-aminobutyric acid (GABA) transporter from mouse retina, to examine its biochemical and pharmacologic properties, and to determine the sites of its mRNA expression in retinal cells. METHODS: A mouse retinal cDNA library was screened using a fragment of a rat brain GABA transporter (GAT-1) cDNA as a probe. One homologous clone, mouse retinal GAT-1, was chosen for further characterization. RNA transcribed from mouse retinal GAT-1 was microinjected into Xenopus oocytes, and pharmacologic properties of the expressed transporter were determined. Sites of mouse retinal GAT-1 mRNA expression were examined by in situ hybridization. RESULTS: The protein sequence deduced from the DNA sequence of mouse retinal GAT-1 cDNA was virtually identical to that of the rat and the mouse brain GAT-1. RNA transcribed from this clone induced a [3H]-GABA uptake activity in microinjected Xenopus oocytes that was both sodium and chloride dependent. The apparent Km and Vmax for the GABA uptake were 8.3 microM and 40.0 pmol/egg per hour, respectively. The mouse retinal GAT-1 induced GABA uptake was inhibited by L-diaminobutyric acid, guvacine, cis-4-hydroxynipecotic acid, nipecotic acid, and 4,5,6,7-tetrahydroisoxazolo [4,5c]-pyridin-3-ol with IC50 values of 320, 79, 71, 7.1, and 200 microM, respectively. However, beta-alanine was unable to inhibit the induced GABA uptake significantly (IC50 approximately 2,500 microM). In situ hybridization studies showed that mouse retinal GAT-1 mRNA was present in a subpopulation of amacrine, interplexiform, and displaced amacrine cells. Hybridization signal in the Müller cells was significantly lower, and GAT-1 transcripts were not detected in the bipolar, horizontal, or photoreceptor cells of mouse retina. CONCLUSIONS: The mouse retinal GAT-1 cDNA encodes a Na(+)-dependent, high-affinity GABA transporter that is mainly expressed in a subset of mouse retinal inter neurons.

Animals↗
PubMed1994

[Infectious endocarditis in non-addict patients without predisposing heart disease. Differential features].

INTRODUCTION AND AIMS: Although uncommonly, infective endocarditis in non-addict patients may involve people without predisponente heart disease. The aim of our study was to assess the clinical and prognostic features of this type of endocarditis and to compare them with those of the more common type of endocarditis with underlying lesion. METHODS: With this aim, we have reviewed 71 consecutive cases of non-addict infective endocarditis diagnosed in our hospital in the last 7 years; there was no preexisting cardiac lesion in 9 patients (13% of all endocarditis and 21% of native valve endocarditis), while underlying heart disease, including mitral valve prolapse, was present in the remaining 62 patients. RESULTS: Mean age was significantly lower in 9 patients without preexistent lesion (28 +/- 18 versus 46 +/- 17 years, p < 0.01), while there was no differences for gender. Infection involved the aortic valve in 56%, the tricuspid or pulmonary valve in 33% and the mitral valve in only 11% of the patients without underlying cardiopathy (for 44%, 4% and 49%, respectively, in patients with cardiopathy). Staphylococcus aureus caused 67% of cases in patients without cardiopathy and only 9% in those with cardiopathy. Surgery was required in a similar proportion by both groups of patients (55% and 56%), although mortality was more than twice higher in patients with prior cardiac lesions (25% versus 11%). CONCLUSIONS: A significant proportion of non-addict infective endocarditis involves patients without predisponente heart disease. These cases have some differential features (younger age, aortic and right heart valves involvement, S. aureus as the main causative agent and lower mortality) in comparison to those of endocarditis in patients with underlying cardiopathy.

Adolescent↗
PubMed1994

[The incidence, mechanisms and clinical factors predictive of sudden death in patients with severe heart failure evaluated in anticipation of heart transplantation].

INTRODUCTION AND OBJECTIVES: Sudden death is not uncommon in patients with severe congestive heart failure. The aim of our study was to assess the incidence, mechanisms and clinical predictors of sudden death in a large series of patients with severe congestive heart failure evaluated for heart transplantation. METHODS: With this aim we have reviewed our experience on 240 consecutive patients with severe heart failure studied in our hospital from May 1986 to June 1992. Heart failure was due to ischemic heart disease in 35% of patients and idiopathic dilated cardiomyopathy in 65%. Age was 47 +/- 12 years, left ventricular ejection fraction was 20 +/- 6%, and symptom class was IV in 88% of patients and III in 12%. RESULTS: Sixty-eight of the 240 patients (28%) died without transplantation. Death was sudden in 21 patients (31% of deaths, and 9% of all patients), due to heart failure in 41 (68%), and due to malignancy (ampuloma) in 1 (1%). Mechanism of sudden death could be identified in 12 cases: ventricular tachycardia/fibrillation in 8 and bradycardia/electromechanical dissociation in 4. On multivariate analysis (stepwise logistic regression), a lower tolerated captopril dosage (p = 0.004), a lower systolic blood pressure (p = 0.079) and a history of a ventricular tachycardia/fibrillation (p = 0.073) were independent predictors of sudden death. CONCLUSIONS: It seems possible to identify, between patients with severe heart failure, a subgroup of patients at higher risk for sudden death by means of such simple clinical parameters.

Acute Disease↗
PubMed1994

[Infectious endocarditis due to Q fever: a recurrent disease. Apropos a new case].

We report a case of a patient with an aortic prosthetic valve who had Q fever endocarditis, glomerulonephritis and rapidly progressive renal failure. He was seen in 1987 and successfully treated by heart valve surgery and a one-year course of doxycycline. Five years later, the patient had another episode of Q fever endocarditis, involving the native mitral valve, complicated with acute renal failure and severe mitral regurgitation that required hemodialysis and mitral valve replacement. The outcome was again successful. This case report raises the question of whether Q fever endocarditis can be eradicated, and also the required duration of antibiotic therapy for this disease.

Acute Kidney Injury↗
PubMed1993

99mTc-sestamibi uptake and retention during myocardial ischemia and reperfusion.

BACKGROUND: 99mTc-methoxyisobutyl isonitrile (Sestamibi) is a new perfusion agent that has shown promise for the noninvasive detection of myocardial salvage after coronary reperfusion in acute myocardial infarction. The objective of this study was to further validate that myocardial uptake and retention of Sestamibi after reperfusion in a canine myocardial infarction model are markers of tissue viability. The hypotheses tested were that if Sestamibi is given early after reperfusion and myocardial uptake is quantitated soon afterward, the degree of ultimate myocardial salvage will be overestimated, and that there will be continued loss of myocardial Sestamibi from ischemic tissue during 3 hours of reperfusion due to accelerated release of Sestamibi from cells already irreversibly injured during the phase of coronary occlusion, reperfusion injury to myocytes still viable early after reflow, or a combination of both mechanisms. METHODS AND RESULTS: In protocol 1, 8.0 mCi Sestamibi was injected intravenously in anesthetized dogs 2-5 minutes after reperfusion preceded by 3 hours of left anterior descending coronary artery (LAD) occlusion. Animals were killed either 5 minutes (n = 7) or 3 hours (n = 9) after Sestamibi administration. Mean endocardial Sestamibi activity was 74 +/- 3% of nonischemic activity in dogs killed early and 31 +/- 2% of nonischemic activity in dogs killed late after Sestamibi administration, indicating myocardial loss of Sestamibi during 3 hours of reflow. Regional flow (percent nonischemic) at the time of Sestamibi administration (2-5 minutes after reperfusion) was comparable in dogs killed early (144 +/- 23%) and dogs killed late (118 +/- 4%, p = NS). In protocol 2, Sestamibi was given intravenously at baseline under normal conditions followed by 3 hours of LAD occlusion and either 4 (n = 6), 30 (n = 9), or 180 minutes (n = 10) of reperfusion. At postmortem, myocardial slices were imaged for quantification of defect magnitude and regional flow (radiolabeled microspheres), and tissue Sestamibi activities were determined by gamma well counting. Coronary sinus Sestamibi activity was serially measured. In these dogs, which were preloaded with Sestamibi at baseline, 3 hours of LAD occlusion followed by 3 hours of reperfusion resulted in a loss of Sestamibi in the endocardial zone of the ischemic region to 40 +/- 6% of nonischemic levels (p < 0.0001). This loss corresponded to a sustained elevation of coronary sinus activity throughout the reflow period. The loss of myocardial Sestamibi was significantly greater than that observed in dogs killed 4 or 30 minutes after reflow. Defect magnitude also worsened over 3 hours of reperfusion as assessed by gamma camera imaging of slices of the excised hearts. CONCLUSIONS: These experimental data suggest that Sestamibi uptake and retention are dependent on myocardial viability as well as regional flow. If Sestamibi is administered early after reperfusion and imaging is performed soon afterward, the degree of myocardial salvage could be significantly overestimated.

Animals↗