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Biomedical subjects

M Rodríguez

Publications and source records attributed to M Rodríguez.

At least 91 records · Page 5Linked to original sources
PubMed2001

[Clinical Characteristics and Evolution of Recurrent Infectious Endocarditis in non Drug Addicts].

INTRODUCTION AND OBJECTIVES: Recurrence of infection is observed in a high proportion of patients who have had infective endocarditis in the past. The aim of our study was to evaluate the possible differences between the first and the recurrent episodes of endocarditis, as well as to assess the outcome and prognosis of patients with recurrent endocarditis. PATIENTS AND METHOD: We reviewed a series of 13 episodes of recurrent endocarditis from among 196 cases of infective endocarditis involving non-drug-addict patients in two hospitals from 1987 to 2000. RESULTS: There were no differences between recurrent and first episodes of endocarditis according to age, sex, heart valve involved or causal microorganisms. Prosthetic valve endocarditis was more common in patients with recurrent endocarditis (86% versus 27%; p < 0.001). Although there were no differences in the rate of complications or early surgery, overall mortality was significantly higher in patients with recurrent endocarditis (53% versus 27%: p < 0.05). When early and late mortality were analysed separately, the differences did not achieve significance. CONCLUSIONS: Recurrent endocarditis was frequent in our series (7% of all cases). The features were similar to those of the first episode except for a higher rate of prosthetic valve endocarditis and a higher overall mortality.

Endocarditis, Bacterial↗
PubMed2001

Biological screening of plants of the Venezuelan Amazons.

A total of 21 extracts derived from 17 different plant species collected in Venezuelan Amazons have been tested for the following biological activities: cardiovascular activity, brine shrimp lethality, and inhibitory effects on the hydrolysis of glucose-6-phosphate in intact and disrupted microsomes. Eight extracts diminished rat blood pressure with or without changes in heart rate. The fruit extract of Swartzia leptopetala and the leaf and twig extract of Connarus lambertii resulted in death of experimental animals. The majority of extracts (17 extracts) showed significant toxicity against Artemia salina. Concerning the hydrolysis of glucose-6-phosphate, better inhibitory effects were observed in intact microsomes than in disrupted ones for all the extracts, suggesting that these extracts intervene with variable potency in glucose-6-phosphate transport through the microsomal membrane.

Animals↗
PubMed2001

Biological activity of Guatteria cardoniana fractions.

Methanolic extract of leaves and twigs of Guatteria cardoniana R.E. Fries (Annonaceae), a plant from the Venezuelan rain forest, was separated in alkaloid rich fractions and their biological effect on baby hamster kidney (BHK) cell line was studied. The initial plant extract (FA) induced cell proliferation, cytotoxicity as well as antiviral activity, depending on the concentration used. Further separation of this methanolic extract allowed us to separate these biological activities. The fraction with the highest antiviral activity (F7) was chromatographed and three of the nine alkaloid-rich fractions obtained, retained this activity. One of them (F(7)11) exhibited the highest inhibitory effect against a neurotropic Sindbis virus (NSV).

Animals↗
PubMed2001

Protein intake, control of serum phosphorus, and relatively low levels of parathyroid hormone in elderly hemodialysis patients.

In maintenance hemodialysis (MHD) patients, advanced age is a factor associated with relative hypoparathyroidism and an adynamic bone. However, the underlying mechanism remains elusive. The aim of the present study was to analyze whether the observed spontaneous decrease in protein intake in the elderly favors a better control of serum phosphorus (P) and parathyroid hormone (PTH) levels. A cross-sectional study including 207 MHD patients (mean age, 60 +/- 14; 59% males; time on dialysis, 61 +/- 55 months) dialyzed 3.5 to 4.5 hours 3 times a week using bicarbonate hemodialysis from 6 Spanish hemodialysis centers was performed. In 95 patients, the nutrient intake was recorded over a 5-day period, and average daily ingestion of nutrients was calculated using a computerized diet analysis system. One-way analysis of variance showed that serum phosphorus and intact PTH decreased with age. In addition, patients with serum phosphorus lower than 4 mg/dL as compared with those with serum phosphorus greater than 4 mg/dL were older (68 +/- 9 v 58 +/- 15 years, P < 0.001), had a lower protein (0.86 +/- 0.3 v 1.05 +/- 0.4 g/kg body weight, P < 0.01) and caloric intake (21.9 +/- 7.4 v 25.7 +/- 8.3 kcal/Kg body weight, P < 0.01), and had lower PTH levels (102 +/- 155 v 290 +/- 345 pg/mL, P < 0.001). An inverse and significant correlation was observed between age and protein intake (r = -0.48; P < 0.01), caloric intake (r = -0.37, P < 0.01), serum phosphorus concentration (r = -0.40; P < 0.01), and PTH levels (r = -0.26; P < 0.01). Additionally, a significant positive correlation was found between serum phosphorus and PTH levels (r = 0.40; P < 0.01). The results obtained in the present study suggest that a lower serum phosphorus level due to spontaneous reduction of protein intake might contribute to the relative low PTH levels observed in elderly hemodialysis patients.

Age Factors↗
PubMed2001

Adsorption of methabenzthiazuron on six allophanic and nonallophanic soils: effect of organic matter amendment.

This article reports on methabenzthiazuron [1-(1,3-benzothiazol-2-yl)-1,3-dimethylurea] (MBT) adsorption process on six agricultural allophanic and nonallophanic soils. The effect of amendment with exogenous organic matter was also studied. Adsorption kinetic fits an hyperbolic model. MBT adsorption reached an apparent equilibrium within 2 h and followed a second-order reaction. The maximum adsorbed amounts for natural soils ranged from 32 to 145 microg g(-1). Rate constants were considered relatively low (0.27-1.5 x 10(-4) [microg g(-1)](1-n) s-1); the slow process was attributed to a combined effect of difussion and adsorption. MBT adsorption fits the Freundlich model with r values > or =0.998 at P < or = 0.001 significance levels. Kf and Freundlich exponents (l/n) ranged from 5.3 to 82.1 cm3 g(-1) and from 0.66 to 0.73, respectively. Kf values for soils with a low organic matter content were lower than that obtained from the only typical allophanic soil derived from volcanic ash under study. Lineal regression analysis between Kf and organic matter content of nonallophanic soils gave a correlation coefficient of 0.980 (P = 0.02). Dispersion of Kd values together with close values of K(OM) indicate that organic matter (OM) was the principal component responsible for MBT adsorption in unamended soils. Addition of peat decreased soil pH and increased adsorption capacity for allophanic and nonallophanic soils. Kinetic experiments showed enhancements of Xmax values and lower rate constants.

Adsorption↗
PubMed2001

Contribution of dietary and newly formed arachidonic acid to human milk lipids in women eating a low-fat diet.

BACKGROUND: Polyunsaturated fatty acids in milk are derived from direct intestinal absorption, endogenous synthesis, or maternal body stores. Arachidonic acid (AA) intake is frequently low in undernourished women, but milk secretion of this fatty acid is similar to that in well-nourished women. OBJECTIVE: The objective was to evaluate the contribution of dietary and endogenously synthesized AA to its total secretion in the milk of women eating a low-fat diet. DESIGN: Ten lactating women who habitually ate a low-fat diet (17% of energy) received 2.5 mg [(13)C]linoleic acid (LA)/kg body wt orally 5 mo postpartum. LA and AA concentrations and (13)C enrichment were measured in milk samples collected before and after the tracer application. Total lipid, LA, and AA contents were determined in diet composites. Fatty acids were assessed by gas chromatography and (13)C enrichment by isotope ratio mass spectrometry. RESULTS: The cumulative 72-h recovery of [(13)C]LA in milk was 16.3 +/- 6.4% of the dose; only 0.01% of the label was found as [(13)C]AA. The calculated transfer of dietary LA and AA into milk was 32.8 +/- 18.0% and 11.8 +/- 6.6%, respectively. AA originating from conversion of dietary LA contributed only 1.1% to the total milk AA secreted. CONCLUSIONS: Little milk AA originates from conversion of LA; 70% of LA and 90% of AA secreted in milk were not derived from direct intestinal absorption. Our results suggest that maternal body stores are the major source of milk LA and AA in these women.

Adult↗
PubMed2001

[13C]linoleic acid oxidation and transfer into milk in stunted lactating women with contrasting body mass indexes.

BACKGROUND: The fat concentration of human milk is associated with maternal adiposity, but there is no clear understanding of the mechanisms controlling milk fat concentration. OBJECTIVE: We evaluated the effect of postpartum body mass index (BMI; in kg/m(2)) on the metabolic distribution of an oral dose of [13C]linoleic acid in lactating women. DESIGN: Ten lactating women stratified by BMI (either <22.5 or >23.5) at 5 mo postpartum received orally 2.5 mg [13C]linoleic acid/kg body wt. Exhaled air, milk, and plasma samples were collected in relation to tracer administration. Linoleic acid was determined by gas chromatography. Dietary intake, serum, milk composition, [13C]linoleic acid enrichment in milk and plasma, and exhaled 13CO2 (by isotope ratio mass spectrometry) were assessed. RESULTS: Women with a higher BMI exhaled more 13CO2 than did women with a lower BMI (22.8 +/- 9.4% compared with 8.6 +/- 3.5% of dose, P < 0.03). Cumulated 72-h transfer of [13C]linoleic acid to milk was not significantly different between groups (14.8 +/- 6.5% compared with 17.7 +/- 6.7% of dose). Within the first 9 h after dose administration, 51.6 +/- 4.9% of the total isotope transfer into milk had passed in women with a higher BMI, but only 24.0 +/- 15.3% had passed in those with a lower BMI (P = 0.02). CONCLUSIONS: Women with a lower BMI, who were reputed as having less body fat, oxidized and secreted into milk less dietary linoleic acid within 12 h after tracer administration than did women with a higher BMI. In both groups, a large proportion of [13C]linoleic was retained in the maternal compartment, most likely fat tissue, in a slow turnover pool, and released slowly in later hours.

Adipose Tissue↗
PubMed2001

Frequency and determinants of microalbuminuria in mild hypertension: a primary-care-based study.

OBJECTIVE: To evaluate the frequency of microalbuminuria and its relationship with several risk factors and left ventricular mass in a population of mildly hypertensive subjects attended in a primary-care setting. DESIGN: Cross-sectional study. SETTING: Eight primary-care centres. PATIENTS: Two hundred and twenty-three non-diabetic patients recently diagnosed with mild hypertension were included in the study. None of them had clinical evidence of target-organ damage or had received prior antihypertensive treatment. INTERVENTIONS: Subjects included in the study underwent clinical interview, measurement of blood pressure (BP) on three visits, blood analysis, measurement of albumin by immunonephelometry in three overnight urine collections, 24 h BP monitoring and M-mode and Doppler echocardiography. MAIN OUTCOME MEASURES: Tobacco habit, clinic BP, body mass index, serum lipids and uric acid, glycaemia, urinary albumin excretion (UAE), ambulatory BP and left ventricular mass index. RESULTS: The frequency of microalbuminuria was 7.2%. Microalbuminuric patients were more likely to be men and to be characterized by higher ambulatory BP, body mass index and uric acid levels. Regression analysis demonstrated that male sex and 24 h systolic BP were determinants of UAE. Patients with white-coat hypertension showed lower UAE than did subjects with sustained hypertension. Although a certain relationship between UAE and left ventricular mass index was found, these variables were not significantly correlated. CONCLUSIONS: A low proportion of mildly hypertensive patients attended in a primary care setting are microalbuminuric. In this population, UAE is an expression of BP values over 24 h and correlates with several risk factors.

Adult↗
PubMed2001

Variation at the Angiotensin-converting enzyme and endothelial nitric oxide synthase genes is associated with the risk of esophageal varices among patients with alcoholic cirrhosis.

Esophageal varices are a frequent complication among patients with liver cirrhosis. Nitric oxide and other vasoactive molecules regulate the vascular tone in both the liver microcirculation and the systemic and splanchnic circulation. Several genes that encode proteins involved in the maintenance of vascular tone, such as the endothelial-constitutive nitric oxide synthase (ecNOS), the angiotensinogen (AGT), the angiotensin-converting enzyme (ACE), and the angiotensin II receptor type 1 (AT1R) are polymorphic, and these polymorphisms have been associated with several cardiovascular diseases. Our aim was to define a possible role for DNA polymorphisms at these genes in the risk of developing esophageal varices among patients with alcoholic cirrhosis. We analyzed 145 male patients with liver cirrhosis. Patients and 200 healthy controls were genotyped by polymerase chain reaction for the ACE-I/D, the AGT-M235T, the AT1R-A1166C, and the ecNOS-4/5 (intron 4) polymorphisms. Ninety-five patients had varices and 50 did not show this complication. Carriers of the ACE-I allele (ID + II genotypes) were at a significantly higher frequency among patients with varices (p = 0.013). Patients without varices had a higher frequency of the ecNOS-4 allele compared with patients with varices (p = 0.026). ACE-I carriers + ecNOS-55 were at a significantly higher frequency (p = 0.0012; odds ratio = 3.19; 95% CI = 1.55-6.55) among patients with varices (51 of 95, 54%) compared with patients without (18 of 50, 36%). Allele and genotype frequencies for the AGT and AT1R polymorphisms did not differ between the two groups. The genotypes associated with an increased risk for varices have been linked to higher plasma levels of nitric oxide and reduced levels of ACE. These genotypes could have a vasodilatory effect in the systemic and splanchnic circulation, thus favoring the development of portocollaterals.

Adult↗
PubMed2001

Hepatocellular carcinoma in HIV-infected patients with chronic hepatitis C.

OBJECTIVES: Chronic hepatitis C is frequently seen in HIV-positive subjects infected through needle sharing or transfusion of contaminated blood products. Progression to end-stage liver disease seems to occur faster in these patients. As the life expectancy of HIV-infected persons has dramatically improved since the introduction of highly active antiretroviral therapies, cirrhosis and eventually hepatocellular carcinoma (HCC) may be recognized at an increasing rate in patients coinfected with HIV and hepatitis C virus (HCV). METHODS: We identified the main features of HIV-infected individuals with end-stage liver disease due to HCV infection and diagnosed with HCC in three HIV/AIDS referral centers, and compared these features to those of a control group of patients with HCV-related HCC but without HIV infection. RESULTS: Seven HIV-infected patients were identified. Of these, six were <45 yr of age and had been intravenous drug users. The mean time between exposure to HCV and the development of HCC was estimated to be 17.8 yr. Two subjects were coinfected with hepatitis B and delta viruses, respectively. Only one individual had been diagnosed of an AIDS-defining condition before the diagnosis of HCC was made. However, all subjects had < 500 CD4+ T cells at the time of HCC diagnosis. Five died within the first 4 months of follow-up. Patients in the control group (n = 31) were significantly older (68.9 +/- 8.9 vs 42.2 +/- 10.4; p < 0.001) and the duration of HCV infection was significantly longer (28.1 +/- 10.9 vs 17.8 +/- 2.7; p < 0.05) than in those with HIV-HCV coinfection. CONCLUSIONS: HCC seems to occur at a younger age and after a shorter period of HCV infection in subjects coinfected with HIV. Thus, treatment of CHC should be encouraged in HIV-positive patients, and in those with HCV-related cirrhosis the periodic monitoring of alpha-fetoprotein and abdominal ultrasonography should be recommended.

AIDS-Related Opportunistic Infections↗
PubMed2001

Role of adhesion molecules in mononuclear cell apoptosis induced by cuprophan hemodialysis membranes.

BACKGROUND/AIM: Hemodialysis with Cuprophan (CU) membranes induces mononuclear cell activation, leading to increased expression of adhesion molecules, formation of cell aggregates, and apoptosis. It is likely that structure(s) of the CU membrane interact with mononuclear cell surface molecules which transduce biochemical signals to the cell. Interactions between adhesion molecules and extracellular matrix have been implicated in cell activation, proliferation, and/or apoptosis. In the present work, we study whether adhesion molecules may be involved in CU-induced mononuclear cell aggregation and/or apoptosis. METHODS: The present study was performed using THP-1 cells, a human monocytic cell line, cultured in the presence of the CU membrane. CD11b and CD54 expression was studied with fluorescent monoclonal antibodies. Cell aggregation was quantified using a phase-contrast microscope. Apoptosis was evaluated by either light microscopy or annexin V labeling. RESULTS: The results show that incubation of CU membranes with the proteins CD11b, CD18, and CD54 or the blockade of these cell surface molecules with specific monoclonal antibodies inhibited the CU-induced aggregation and apoptosis in a dose-dependent manner. CONCLUSION: These results suggest that CU membranes interact selectively with these specific proteins to induce cell activation which ultimately results in apoptosis.

Apoptosis↗
PubMed2001

Potential role of a new anti-beta3 integrin antibody in the development of intimal hyperplasia after vascular surgery: an in vitro smooth muscle cell model.

The occurrence of intimal hyperplasia after vascular surgery is an ongoing concern in current clinical practice. Among the many factors involved in the development of this pathology, platelet adhesion and myointimal proliferation play a major role. Both these processes are mediated by integrins (mainly alphavbeta3 integrins). Over the past years, several substances have been designed to delay or inhibit the cell proliferation that leads to hyperplasia and mainly include monoclonal antibodies directed against integrins. The aim of the present study was to evaluate the effects of an antibody denoted P37 (anti beta3 integrin) on human smooth muscle cells (SMC) and its role in blocking the B3 subunit. To this end, SMC from human umbilical artery were cultured in the presence or absence of the cell substrate vitronectin (VN) and incubated with P37. After 4 days of treatment, determination was made of cell proliferation and migration. Smooth muscle cells grown on VN showed increased proliferation and migration compared to control VN-free cultures. However, the presence of P37 in the culture medium inhibited proliferation and reduced migration. Combined treatment with VN and P37 led to improved proliferation but VN was unable to reverse the effects on migration observed in the former cultures. Results suggest that in vitro, P37 is capable of blocking human SMC beta3 integrins and thus impedes cell proliferation and migration These findings may have clinical implications related to modulation of the development of hyperplasia.

Antibodies↗
PubMed2001

Broad band spectral measurements of EEG during emotional tasks.

Broad band spectral measurements were calculated on EEG recordings of 40 healthy male university students during emotional tasks using the emotion induction technique. Emotional stimuli were sentences with positive valence (joy of love), with negative valence (frustration) and neutral situation. Broad band measurements showed that delta and beta bands reflected better the differences by emotional state. Hemispheric differences associated to emotional states were obtained only for mean frequency data. Higher delta frequencies at left frontopolar, right frontal, parietal and temporal and higher beta frequencies at left frontotemporal and temporal were related to love. Meanwhile higher delta frequencies especially at left frontopolar and temporal regions and lower beta frequencies at midline frontal (Fz) and central (Cz) leads were associated to frustration. These findings suggest that narrow band measurements may reflect more efficiently EEG changes during emotional tasks.

Adult↗
PubMed2001

Analysis time and lactation stage influence on lactoperoxidase system components in dairy ewe milk.

To study the effect of time elapsed from the moment of taking samples on lactoperoxidase system components, we analyzed the activity of the lactoperoxidase enzyme and the concentrations of thiocyanate and hydrogen peroxide in 46 individual samples of Manchega ewe milk. Samples were maintained at a temperature of 4 degrees C until analysis, which took place at 6, 12, 24, and 48 h after extraction. Decreases were observed in lactoperoxidase activity when the analyses were performed at 48 h and in the thiocyanate and hydrogen peroxide concentrations at 12 h compared with those carried out earlier. Consequently, when the components of the lactoperoxidase system or its antibacterial activity are studied, the time elapsed since the sampling commenced must be taken into account. Similarly, the time elapsed is important when carrying out bacterial counts or residue screening by microbiological methods, during which the lactoperoxidase system may interfere. To study the component changes in the lactoperoxidase system during lactation, samples obtained 15, 30, 45, 60, 75, 90, 105, 120, and 135 d postpartum from 48 Manchega ewes were used. Average lactoperoxidase activity, thiocyanate, and hydrogen peroxide concentrations were 3.46 U/ml, 6.89 mg/L, and 0.39 mg/L, respectively, with significant variations throughout lactation. The thiocyanate and hydrogen peroxide levels at different lactation stages seemed to be insufficient to activate the lactoperoxidase system. Nevertheless, this could be achieved by adding 5 mg/L of thiocyanate and 8 mg/L of hydrogen peroxide at any time during lactation.

Animals↗
PubMed2001

Colocalization of tyrosine hydroxylase and GAD65 mRNA in mesostriatal neurons.

Although dopamine has been considered as the only neurotransmitter in the nigrostriatal pathway, studies carried out in the last two decades have suggested the existence of a nondopaminergic nigrostriatal projection, and more recently, gamma-aminobutyric acid (GABA) has been identified as its neurotransmitter. In this study, we used the combination of immunocytochemistry for tyrosine hydroxylase (TH; a marker of dopaminergic neurons), in situ hybridization (ISH) for two different isoforms of glutamic acid decarboxylase (GAD65 and GAD67, the rate-limiting enzyme in GABA synthesis) and retrograde tracing techniques to investigate the possible existence of nigrostriatal neurons containing both neurotransmitters (dopamine and GABA) in the rat. Our results revealed that approximately 10% of mesostriatal dopaminergic neurons, most of them lying in the medial region of the substantia nigra pars compacta (SNC) and neighbouring A10 region, contain GAD65 mRNA. These findings reveal a third nigrostriatal pathway formed by dopaminergic/GABAergic neurons. Contrasting with the idea that in the basal ganglia, dopamine and GABA are released from different cell populations, the results suggest a more complex dopamine/GABA interaction than previously assumed, probably including cotransmission.

Animals↗
PubMed2001

[Disabling malformations in Chile. Latin American Cooperative Study of Congenital Malformations (ECLAMC), 1982-1997].

BACKGROUND: The ECLAMC (Estudio Colaborativo Latinoamericano de Malformaciones Congénitas) is an epidemiological surveillance program for congenital defects that operates in Chile since 1969. AIM: To communicate the frequency of disabling congenital defects in Chile in the period 1982-1997. MATERIAL AND METHODS: A review of the ECLAMC registry, choosing 12 congenital defects: amelia, limb amputations, limb reductions, arthrogryposis, hip luxation and subluxation, spina bifida, hydrocephaly, microcephaly, cephalocele, talipes equinovarus, Down syndrome and multiple abnormalities. RESULTS: In the study period, 283,403 births occurred and 7,917 newborns were malformed (7,654 born alive and 263 stillbirths). The congenital defects prevalence rates appeared higher in Chile than in other Latin American countries, specially among stillbirths. Among the studied maternity hospitals, the Clinical Hospital of the University of Chile, showed the higher prevalence of congenital defects. Rancagua and the Navy Hospital in Valparaiso have a high frequency of Down syndrome. Global rates in Chile and in the rest of ECLAMC for specific defects, do not have significant differences, except for hip subluxation, that has a lower incidence in Chile. CONCLUSIONS: The ECLAMC allows to have a good knowledge of the prevalence of congenital malformations in Latin America.

Chi-Square Distribution↗