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Biomedical subjects

J Vásquez

Publications and source records attributed to J Vásquez.

14 recordsLinked to original sources
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↗
PubMed2000

Endothelial dysfunction in arterial hypertension.

Systemic arterial pressure is a dynamic and reactive physiological parameter depending on a great many factors. The endothelial cells of the vascular system are responsible for many biochemical reactions maintaining vascular homeostasis and therefore arterial pressure. Arterial hypertension, atherosclerosis and endothelial dysfunction constitute risk factors increasing morbidity and mortality of cardiovascular origin. These three elements are closely related and frequently act simultaneously damaging different organs. In this paper we review the physiology of the endothelium and the probable consequences of endothelial dysfunction on the pathophysiology of arterial pressure.

Arteries↗
PubMed1997

Antibody levels against alpha-galactosyl epitopes in sera of patients with squamous intraepithelial lesions and early invasive cervical carcinoma.

We measured serum levels of anti-Gal(alpha 1-->3)Gal and anti-Gal(alpha 1-->2)Gal antibodies in 89 and 91 women, respectively, by using ELISA. These patients had cervical intraepithelial neoplasia (CIN) grades 1 to 3 and early invasive cervical carcinoma (ICC). Our objective was to compare anti-alpha-galactosyl antibody levels among them and with those of normal controls. High levels of anti-Gal(alpha 1-->2)Gal antibodies were detected in 22% of patients (P = 0.006). The mean level was 1.6 times greater than that of controls, without difference among subgroups. Thirty percent of patients had abnormally high anti-Gal levels (P = 0.001). Mean levels were twofold greater than the mean control value. Subsets with human papillomavirus/CIN 1 and CIN 2-3 had high immunoreactivity (P = 0.004). Both antibodies showed a significant correlation (r = 0.53, P < 0.00001). We conclude that 22 to 30% of patients with CIN 1-3 showed significantly high levels of anti-alpha-galactosyl antibodies. This seroreactivity might be related to the abnormal expression of alpha-galactosyl residues at some point of the natural history of human papillomavirus infection of the uterine cervix, suggesting an active immune response by natural antibodies against this virus. Further studies are needed to determine whether anti-alpha-galactosyl antibodies confer protection in human papillomavirus infection.

Adult↗
PubMed1997

Pharmacological modulation of the cardiovascular response to hypertonic NaCl injection in the anteroventral area of the rat brain third ventricle.

The anteroventral area of the rat brain third ventricle (AV3V) was stimulated by stereotaxically placed microinjections (1 microliter) of hypertonic 1.5 mol/l NaCl and the responses of mean arterial pressure (MAP) and heart rate (HR) were recorded. Previous injection of terazosin or propranolol (5.0 micrograms) into AV3V, 15 min before 1.5 mol/l NaCl microinjection, did not alter the cardiovascular response pattern induced by 1.5 mol/l NaCl. Prior AV3V treatment with ketanserin (1.0 microgram) significantly reduced (p < 0.01) the MAP and HR increase induced by 1.0 microliter of 1.5 mol/l NaCl without changing basal cardiovascular parameters. Prior AV3V treatment with losartan (10.0 micrograms) significantly reduced (p < 0.01) the hypertension and tachycardia induced by hypertonic NaCl administration. Thus, AV3V serotonin and angiotensin II-sensitive neurons may exert an excitatory role on blood pressure and HR involved with the sympathetic discharge produced by hypertonic NaCl stimulation.

Angiotensin I↗
PubMed1997

Validity of colposcopy to identify and grade squamous intraepithelial lesions among Venezuelan women.

To assess the validity of colposcopy to correctly detect and grade squamous intraepithelial lesions (SIL) in Venezuelan women, we did a prospective, nonrandomized and cross sectional study on patients referred with low-grade and high-grade SIL. After a second cervical smear, they were colposcopically evaluated and biopsied. The outcome measures were interobserver variation, sensitivity, specificity, and predictive values. Ninety-nine patients were evaluable. Colposcopy had poor agreement with repeat cervical smears, and moderate to good agreement with conization biopsy (kappa = 0.55; 95% C.I.: 0.45 to 0.65), with a sensitivity of 0.87, a specificity of 0.69, a positive predictive value of 0.85 and a negative predictive value of 0.71 for high-grade SIL. The criterion of colposcopic vascular atypias was accurate enough to detect and grade SIL, showing good agreement with histopathology. Because of the disparity of results in previous reports, only a carefully designed, randomized study will settle this question.

Adult↗
PubMed1995

Low urinary dopamine excretion associated to low sodium excretion in normotensive Piaroa Amazonian ethnia compared to urban subjects.

The objective of this work was to compare urinary dopamine, noradrenaline, adrenaline, sodium and potassium excretion in a group of normotensive Piaroa Amazonic ethnia who do not use salt in their regular food intake, against a group of urban normotensive citizens known to have a high salt intake in their regular meals. Twenty adult normotensive Piaroa subjects living in the Amazonas forest, 11 men and 9 women, 23-72 years old, and 33 normotensive urban citizens, 25-70 years old, 17 men and 17 women, were included in the study. After a 10 min. rest, an average of three supine systolic (SBP) and diastolic (DBP) blood pressure recordings was obtained. Piaroas subjects SBP and DBP were 111.3 +/- 2.9 mmHg and 62.7 +/- 1.9 mmHg respectively; urban subjects SBP and DBP were 111.8 +/- 2.2 mmHg and 70.3 +/- 1.6 mmHg respectively. Supine heart rate was lower in Piaroas (58.0 +/- 1.8 beats/min) than in urban subjects (76.5 +/- 1.9 beats/min), p < 0.05. Sodium urinary excretion was much lower in Piaroas (12.6 +/- 5.2 mmol/24 h) when compared to urban subjects (210.7 +/- 24.5 mmol/24 h), p < 0.01. No difference was found in daily urinary potassium excretion between Piaroas and urban subjects (50.4 +/- 7.2 mmol/24 h vs 45.1 +/- 7.4 mmol/24 h). Urinary dopamine excretion was lower in Piaroas (314.7 +/- 40.1 micrograms/24 h) in comparison to urban subjects (800.4 +/- 59.2 micrograms/24 h), p < 0.05. Daily urinary noradrenaline and adrenaline excretion were 67.9% and 85.4% respectively lower in Piaroas than in urban subjects. In conclusion, lower amounts of sodium daily intake are associated to lower kidney dopamine production in Piaroas as compared to urban subjects. Apparently indigenous tribes might require less kidney dopamine synthesis to excrete the very small amounts of salt they consume in their regular food intake. The opposite was found in urban subjects; more kidney dopamine synthesis would be required for larger amounts of urinary sodium excretion. In this population, essential hypertension has been associated to a failure of the natriuretic mechanism triggered by dopamine onkidney tubules.

Adult↗
PubMed1995

[Abnormal autonomic cardiovascular responses in patients with sickle cell anemia].

PURPOSE: To evaluate the presence of anomalies of the autonomic reflex cardiovascular response in patients with chronic sickle-cell anaemia. PATIENTS AND METHODS: The study was extended to 30 patients with sickle-cell anaemia, 10 patients with iron-lack anaemia and 30 healthy subjects. Age and sex distribution was similar in each group. To be included in the study, patients should have had no painful crisis or blood transfusion in the 6 months previous to the assay. Clinico-laboratory survey, chest x-ray and EKG were performed in every case. Blood cell count and abnormal haemoglobin study on cellulose acetate were carried out as well. The evaluation of reflex autonomic responses was performed by means of active orthostatism, cold pressor test, Valsalva maneuver and urine catecholamine output. The statistical analysis was performed with the variance analysis (ANOVA) for multiple groups. RESULTS: The following abnormalities were found: 12 patients had haemoglobin SS, 8 had haemoglobin SS and F, 3 had haemoglobin SC, 2 had haemoglobin S and beta-thalassaemia, and 5 had combined haemoglobin SS,F and A2. Systolic pressure and heart frequency in the supine position were similar in all groups. Diastolic pressure was lower in the sickle-cell anaemia group with respect to the normals. Patients with sickle-cell disease had lower heart frequency in the active orthostatism test with regard to the other groups, along with paradoxal changes in systolic pressure and lesser increase of the diastolic pressure. Significantly lower response to the cold pressor test was seen in the sickle-cell patients as compared with the iron-lack cases and the normal controls. Reduced sympathetic tachycardia was seen with the Valsalva maneuver, whereas the bradycardia was similar to the other groups. The urine noradrenaline in output was significantly lower in the sickle-cell patients, it was normal in the other groups (p < 0.01). CONCLUSION: These results suggest a defective sympathetic activity of heart and arteries in patients with sickle-cell anaemia.

Adolescent↗
PubMed1993

[Changes produced by age in cardiovascular reflex responses].

The influence of age on reflex cardiovascular responses, elicited by orthostatic change and Valsalva's maneuver was studied in 105 healthy volunteers, and the response to cold pressor test in 87 healthy adults. The age range of the subjects was 12 to 79 years old; they were stratified by decades for statistical analysis. Included in this study were only subjects without diseases, as evidenced by anamnesis, physical examination, blood pressure recording, ECG tracings, chest X-Ray and routine laboratory tests. None of subjects showed obesity, the body mass index was between 19.6 +/- 0.9 Kg/m2 in the 10-19 year old group and 25.2 +/- 1.2 Kg/m2 in the 50-59 year old group (mean +/- SE). Systolic and diastolic blood pressure (SBP, DBP) were between 113.6 +/- 4.2 and 64.2 +/- 2.9 mmHg respectively in the 10-19 years old group and 139.8 +/- 5.0 mmHg and 79.5 +/- 3.2 mmHg respectively in the 70-79 years old group (mean +/- SE). Heart rate in supine position varied between 71.2 +/- 3.2 beats/min in the 10-19 years group and 75.8 +/- 3.0 beats/min in the 70-79 years old group (mean +/- SE). Orthostatic response. Change from supine to standing position increased mean arterial pressure (MAP) by 10.0 +/- 1.25 mmHg in the 10-19 years old group; a similar increase occurred up to 40-49 years old group; from that age on, the response became bimodal, the percentage of subjects showing a MAP decrease upon standing, increased from 20% in the 50-59 years old group to 48% in the 70-79 years old group; MAP descents ranged between -5.3 +/- 0.63 and -12.6 +/- 1.37 mmHg (mean +/- SE) and were non symptomatic. The same bimodal pattern of responses was observed in the heart rate. Cold pressor test. In the 10-19 years old group the cold pressor test induced an increase of SBP and DBP of 17.6 +/- 5.0 mmHg and 11.5 +/- 3.5 mmHg (mean +/- SE) respectively, this response remained unchanged up to 40-49 years old age. After 50-59 years old this SBP and DBP increase was reduced by 50% and 63% in the 60-69 and 70-79 years old groups respectively. Return of SBP and DBP to cold prestimulation levels was normal in all studied groups.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMedDate not supplied

[Takayasu arteritis: usefulness of radiologic and angiographic studies].

With the purpose of learning the usefulness of radiologic and angiographic procedures for the evaluation of Takayasu's arteritis (TA), we studied 64 patients (ratio women: 8.1, average age: 23.5 years, range: 13-52 years) in which we performed arteriographic studies in the clinically affected area. All cases had chest films: 53 had thoracic aortogram, 60 abdominal aortogram, 16 pulmonary arteriography. According to the topography of the lesions we found 8% of the cases with damage exclusive to the supra-aortic trunk, 6% with isolated alteration of the intermediate thoraco-abdominal aorta, 62% with mixed pathology of the two categories above, and 21% with lesions in the pulmonary artery besides systemic arteriopathy. The results were as follows: 1) radiology of the chest: cardiomegaly (48%), irregularities in the ascending aorta (31%), calcification in the aortic wall (29%), calcified granulomas (25%) and signs of pulmonary venous hypertension (21%); 2) thoracic aortogram: irregularities in the descending aorta (56.6%), thickening of the wall of descending aorta (39.6%), dilatation of the ascending aorta (26.4%), of the descending aorta (26.4%); occlusions: of the left subclavian (24 cases), left mammary (16 cases), left carotid (8 cases) and left vertebral (8 cases); 3) abdominal aortogram: irregularities of the outline, stenosis, prominent "supplementary" arteries and aneurysms in 53%, 43.3%, 38% and 13.3 of the studies performed. The arteries most commonly affected were: renal (74.7%), both (31.6%), right (28.2%) and left (14.9%), superior mesenteric (26.6%) and hepatic (21.6%); 4) pulmonary arteriography: arterial occlusions: right superior lobar branch (37.5%), right medial (6.2%), right inferior (12.5%), without predilection by any lobe; 5) coronary arteriography: one case with occlusion of anterior descending artery and circumflex coronary artery (the other 8 cases without significant lesions). We concluded that TA affects independently the arteries of different areas, hence it is necessary to perform multiple angiographic studies for adequate evaluation of the extension of vascular damage.

Adolescent↗
PubMedDate not supplied

[Congenital intrathoracic right kidney].

Ectopic intrathoracic kidney is an extremely rare congenital disorder. It is generally asymptomatic, being discovered as incidental finding on a routine chest radiograph. Diagnosis is established by an intravenous pyelogram demonstrating an abnormally shaped excretory system with longer than usual ureters, which also helps to differentiate it from other posterior mediastinal tumors, such as neurogenic masses, including neuroblastoma, ganglioneuroma, neurofibroma, neuroenteric cysts, meningoceles and hernia of the foramen of Bochdalek.

Abnormalities, Multiple↗
PubMedDate not supplied

[Increase of renal dopamine production induced by nifedipine in hypertensive patients. Double blind vs placebo study].

Dopamine is synthetized and excreted by kidneys, this amine exerts its natriuretic and diuretic effects by inhibition of sodium reabsorption on kidney convoluted tubules. The objective of this study was to verify the changes of dopamine urinary excretion induced by nifedipine-LP treatment in hypertensive patients. Twenty four patients with essential hypertension (stages 1, 2) were included in this double-blind, placebo controlled study. Twelve patients received nifedipine (average daily dose, 21.5 mg/day) for 4 weeks, and 12 patients received placebo for the same time period. No significant changes were detected upon nifedipine treatment neither in plasma biochemical nor hematological parameters. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) was significantly reduced from pretreatment values 168.0 +/- 8.7 mmHg and 102.0 +/- 5.2 mmHg respectively, to end-treatment values 140.0 +/- 6.6 mmHg and 88.0 +/- 5.6 mmHg (p < 0.05). Placebo treatment did not modify SBP and DBP. Urinary dopamine excretion increased by 53% from 679.5 +/- 80.1 micrograms/24 h prior to treatment to 1040.0 +/- 110.1 micrograms/24 h after treatment (p < 0.009. 95% Confidence Interval of the Difference: -538.9 to -183.6). Urinary volume of nifedipine treated patients increased from 1613 +/- 85 mL/24 h to 1920 +/- 160 mL/24 h post-treatment (p < 0.05). No significant changes were observed in urinary noradrenaline and adrenaline excretion in nifedipine or placebo treated patients. Analysis of fluorescent light excitation and emission spectra (200 nm to 800 nm) of dopamine extracted from patient's urine submitted to nifedipine treatment did not reveal any interference when compared to chemically pure dopamine. If is concluded that nifedipine treatment of hypertensive patients increases kidney dopamine production which in turn can exert a natriuretic and diuretic effect besides its well known vasodilator properties.

Adult↗