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Biomedical subjects

M Velasco

Publications and source records attributed to M Velasco.

At least 127 records · Page 7Linked to original sources
PubMed1994

Neurotransmitter levels in cerebrospinal fluid in relation to severity of symptoms and response to medical therapy in Parkinson's disease.

Determinations of biopterin (BP), homovanilic acid (HVA), glutamic acid (GTA), and glutamine (GT) levels in cerebrospinal fluid (CSF) obtained through a lumbar tap were performed in 20 parkinsonian patients in different stages of evolution and without medication. In patients with motor symptoms not related to Parkinson's disease (dystonia, dyskinesia and essential tremor) (n = 4). In 7 other neurological patients subjected to spinal tap for diagnostic procedures neurotransmitters were also determined and taken as control groups. In 14 of the patients with Parkinson's disease, the symptoms were evaluated using conventional scales (UPDS, NYPDS, NWPDS, Schwab and England, and Hoehn and Yahr scale). The amplitude and the frequency of tremor were quantitatively evaluated through a single plane accelerometer Grass SP-1, akinesia was measured through reaction time to auditory stimuli, and rigidity through the speed of lineal movement. Evaluations were performed with the patient not on any medication for 1 week and repeated 1 h after the intake of 250 mg of 200/50 L-dopa/carbidopa preparation (Sinemet) and on a different day after the intake of biperiden (Akineton) 6 mg/day. Differences in neurotransmitter or metabolites levels between Parkinson's disease and control groups were determined through an independent Student's t test. Correlation between severity of symptoms in the scales and for each individual symptom measured through the quantitative tests and the levels of neurotransmitters in CSF were evaluated through the Pearson correlation analysis test. Modifications in the motor performance after administration of Sinemet and Akineton, and the levels of neurotransmitters were indirectly determined. RESULTS. (1) There were significant differences between the levels of BP and GT in patients with Parkinson's disease and control groups, (2) lower GTA levels correlated with more severe rigidity and akinesia, and with the best response to the administration of L-dopa and may be an important marker for prognosis, and (3) lower levels of GT correlated with least akinesia, but not with tremor, which may indicate that the akinesia depends on other biochemical abnormalities besides dopamine depletion.

Adult↗
PubMed1994

[Long term follow-up of patients with chronic hepatitis due to hepatitis C virus].

Thirty two patients (18 males whose ages ranged from 32 to 68 years old) with hepatitis C virus chronic hepatitis (positive anti-HCV by ELISA, confirmed by RIBA II) that were followed by the authors during 2 to 25 years, were retrospectively analyzed. Thirteen subjects had a history of blood transfusions, one had an accidental pinprick and other a sexual contact with a HCV positive individual; the transmission source was not identified in the resting 19 subjects. Only five individuals had an acute onset. The rest of the patients had few symptoms with moderate and fluctuating transaminase elevations. Liver biopsy at the onset showed a chronic hepatitis with moderate activity, even in 15 individuals with cirrhosis (47%). During follow up, six subjects deteriorated clinically, appearing liver failure and three of these died 4, 5 and 14 years after the disease appearance. No subject developed a hepatocarcinoma.

Adult↗
PubMed1993

Unusual breast edema and erythema during radiotherapy in the conservative approach of breast cancer. A case report.

The appearance of breast edema in the conservative approach of breast cancer is correlated with axillary dissection, and it is worsened by radiotherapy. In rare cases there are serious edema and erythema of the breast at the beginning of radiotherapy. We present a patient with edema and erythema of the breast with an unusual evolution after conservative surgical treatment of the breast cancer. Possible etiologies and published data are reviewed.

Aged↗
PubMed1993

Role of the centromedian thalamic nucleus in the genesis, propagation and arrest of epileptic activity. An electrophysiological study in man.

Twenty-eight patients underwent electrical stimulation of the centromedian (CM) thalamic nucleus as a neuro-augmentative procedure to control intractable seizures of various types. To assess the correct placement of electrodes, electrical stimulation at 3 and 6 Hz, 1.0 msec and 600-2000 uA pulses in trains of 30-60 sec were used while the EEG was recorded by scalp electrodes. Spontaneous seizure activities of various types were simultaneously recorded. In cases of focal epilepsy depth electrodes were used in order to study the sequence of activation of different structures. Three Hz electrical stimulation induced spike-and-wave complexes accompanied by a typical absence. Eight Hz induced recruiting-like responses with ipsilateral predominance and no clinical manifestations. Interictal spike activity was recorded in the CM in cases of generalized tonic-clonic convulsions (GTCC) and ictal spike pattern in the CM preceded discharges in other areas. In atypical absences cortical and CM discharges occurred simultaneously. It is concluded that the CM participates in the onset of GTCC and typical absences, in the propagation of secondary GTCC but not in myoclonic convulsions.

Electric Stimulation↗
PubMed1993

Effect of intravenous dopamine on blood pressure and plasma insulin in hypertensive patients.

Eleven patients with moderate to severe hypertension were pre-treated with oral labetalol 800-1200 mg/day for one week, prior to receiving two i.v. infusions of dopamine 1-3 micrograms/kg/min each of 30 min each, before and after the i.v. bolus injection of metoclopramide 30 mg. There were washout periods before and after the metoclopramide administration. Dopamine induced a significant decrease of blood pressure from 172/104 to 153/94 mm Hg without altering heart rate, and it increased the plasma insulin level from 8.3 to 12.1 microU.ml-1. Metoclopramide did not itself affect blood pressure or plasma insulin, but it did block the hypotensive response and rise in plasma insulin due to dopamine. We conclude that the pharmacological actions of intravenous dopamine on the cardiovascular system and on insulin secretion may be mediated by dopaminergic receptor stimulation.

Blood Glucose↗
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↗
PubMed1993

[Acquired resistance of M tuberculosis to the antitubercular drugs in Chile from 1988 to 1991].

Acquired drug resistance appears in patients that are or have been in treatment for tuberculosis (relapses, abandons and failures). The aim of this study was to maintain an epidemiologic surveillance on the incidence of acquired drug resistance among previously treated patients and treatment failures. In 896 strains (518 in 1988 and 378 in 1991) coming from these type of patients, the pattern of sensitivity towards agents used in the treatment of tuberculosis was studied. There was an increase in the frequency of acquired resistance from 24.5% in 1988 to 32.3% in 1991. This increment was observed in the group of treatment failures, where the resistance to the combination streptomycin-isoniazid-rifampin had special relevance. This situation is epidemiologically and clinically negative since it generates primary resistance and chronicity. The increment in acquired resistance forces a revision of tuberculosis treatment, specially in its operational features.

Animals↗
PubMed1993

Effects of dopaminergic antagonists on dopamine-induced cardiovascular and insulin secretion actions in hypertensive patients.

A comparative study between two dopaminergic antagonists: metoclopramide and domperidone, was undertaken in nineteen (19) hypertensive patients at the Vargas Hospital, Caracas. The patients were pretreated with labetalol, 800-1,200 mg/day, orally, over a period of one week, after which they were divided into two groups: group A, a total of eleven patients were intravenously infused with dopamine hydrochloride 0.5-3 micrograms/kg/min, before and after treatment with metoclopramide (10 mg, i.v. as a bolus); group B (n = 8), was pretreated with domperidone, 20 mg b.i.d., p.o. over a period of one week and intravenously infused with dopamine hydrochloride, 0.5-3 micrograms/kg/min. In group A, dopamine induced a decrease of blood pressure from 171.9 +/- 6.35/103.6 +/- 3.12 to 152.7 +/- 7.55/93.8 +/- 2.97 mmHg (p < 0.001) without altering heart rate, and it increased plasma insulin levels from 8.29 +/- 0.70 microunits/ml to 12.09 +/- 1.83 microunits/ml (p < 0.01). Metoclopramide caused no changes of blood pressure or plasma insulin levels. However, hypotensive responses and plasma insulin rises due to dopamine were blocked by metoclopramide. In group B, domperidone also blocked dopamine-induced antihypertensive effect (from 170.0 +/- 9.23/102.8 +/- 3.80 to 160.2 +/- 9.84/95.5 +/- 2.50 mmHg) although it was less effective than metoclopramide. Domperidone also blocked dopamine-induced increase of plasma insulin levels from 9.65 +/- 4.50 microunits/ml to 11.78 microunits/ml. We conclude that a dopaminergic receptor may be involved in some cardiovascular responses and in modulating insulin secretion in man.

Blood Glucose↗
PubMed1993

[Post sinusoidal obstruction of the hepatic venous flow associated with antiphospholipid syndrome in 3 cases].

Three cases of post-sinusoidal hepatic blood flow obstruction as the main feature of antiphospholipid syndrome are reported. Clinically, these patients developed jaundice, malaise, ascites and hepatomegaly. Ultrasonography-Doppler and hepatic venography showed small hepatic vein disease in two and partial occlusion in the suprahepatic segment of inferior vena cava in the remaining patient. In all, anticardiolipin antibodies were positive and activated partial thromboplastin time was prolonged. This experience emphasizes that in patients with post sinusoidal portal hypertension, a systematic search for antiphospholipid syndrome must be carried out.

Adult↗
PubMed1993

[Hepatitis B virus vaccine: early and late response in Chileans with high risk of infection].

BACKGROUND: Hepatitis B vaccine has demonstrated to be very effective and safe preventing hepatitis B virus infection. Long term protection induced by hepatitis B vaccination depends on the initial immune response and the declining rate of anti-HBs titers. AIM. To investigate early and late response to hepatitis B vaccine in a sample of high risk Chilean population. MATERIAL AND METHODS: Thirty one subjects (20 relatives of hepatitis B chronic carriers, 10 health service workers and one HIV seropositive) were vaccinated with a plasma derivated hepatitis B vaccine. Early and late response were estimated by anti-HBs titers. RESULTS: Twenty eight subjects (90%) produced protective titers of anti-HBs after 2 months from the third dose of vaccine (early response), and they remained at these levels in 75% of vaccinated individuals after three years (late response). All the subjects without protective titers after the three year follow up had produced anti-HBs levels lower than 300 UI at the early response. Hepatitis B vaccination was not associated with significant side effects. CONCLUSIONS: This experience confirms that hepatitis B vaccine is safe and effective inducing immunity in high risk subjects. Our data suggest that the early response to hepatitis B vaccine is able to identify those subjects requiring closer surveillance for boosters.

Adolescent↗
PubMed1993

[Correlation between serum globulin levels and hepatitis C virus antibody].

BACKGROUND: some studies have suggested that the elevation of serum globulins in patients with chronic autoimmune hepatitis, paraproteinemias and rheumatoid arthritis could affect the determination of false positive hepatitis C virus antibodies (anti-HCV). AIM: to study the relationship between positive anti-HCV and serum levels of globulins in patients with liver disease. PATIENTS AND METHODS: one hundred thirty one patients with liver disease, 49 alcoholic, 38 cryptogenetic, 17 autoimmune and 27 with other causes, were studies prospectively measuring simultaneously anti-HCV and serum levels of total, gamma and immuno-globulins (IgA, IgG and IgM). These levels were compared between anti-HCV positive and negative groups and correlated with the ratio between serum optical density/cutoff optical density of the anti HCV assay. RESULTS: Twenty eight patients (21.3%) were anti-HCV positive, no differences in serum globulins between these patients and anti-HCV negative patients and no correlations between serum globulins and anti-HCV optical densities were observed. CONCLUSIONS: the hypergamma-globulinemia observed in these patients with liver diseases would not be responsible for positive hepatitis C virus antibodies.

Enzyme-Linked Immunosorbent Assay↗
PubMed1992

Micronuclei in bronchial biopsy specimens from heavy smokers: characterization of an intermediate marker of lung carcinogenesis.

Bronchial micronuclei, small fragments of extra-nuclear DNA formed during cell division, provide a non-specific but quantifiable marker of DNA damage. Micronuclei have been used to assess carcinogen exposure and as an intermediate endpoint in chemoprevention trials. As part of an ongoing chemoprevention trial, heavy smokers underwent screening bronchoscopy, with biopsies taken at 6 standardized sites. Micronuclei counts were obtained for each site in each of the 40 volunteers found to have squamous metaplasia. Unlike squamous metaplasia, the average micronuclei counts among these heavy smokers were not associated with smoking history. Micronuclei counts were also not associated with the presence or extent of metaplasia. A striking degree of intra-individual variability was observed by comparing the micronuclei counts from different biopsy sites within individuals. The findings suggest that use of micronuclei from single sites may be misleading as a marker of carcinogen exposure or as an estimate of cancer risk. Serial measurements in individuals may provide the most useful information concerning carcinogenic exposure and the impact of chemopreventive agents.

Adult↗
PubMed1992

Comparative effects of dopaminergic agonists on cardiovascular, renal, and renin-angiotensin systems in hypertensive patients.

The role of dopaminergic receptors on renal function has been extensively studied. Recently dopaminergic receptor has been classified in two subtypes D1 and D2, which seem to have different modulatory function. However, the role of dopaminergic receptors on cardiovascular function and more specifically the potential role of dopaminergic agonists as antihypertensive agents has not yet been clarified. Nine outpatients with mild and moderate hypertension were studied in the Cardiology Service of Vargas Hospital with a D1 agonist, piribedil, at 50-100 mg/day, orally, for 8 weeks, and with a D2 agonist, bromocriptine, at 2.5 - 5 mg/day, orally, for an another 8 weeks by using a placebo comparative crossover design. Piribedil reduced blood pressure with a modest increase in heart rate, plasma renin activity, and of plasma aldosterone, and an important increment of renal function. Bromocriptine reduced blood pressure with a decrease in heart rate and plasma aldosterone without altering renal function. There was no orthostatic hypotension with either agent. The authors conclude that activation of dopaminergic D1 receptor induces a vasodilatory and antihypertensive effect with a reflex increase in sympathetic tone, whereas activation of dopaminergic D2 receptor induces a decrease in sympathetic tone, probably due to a decrease in norepinephrine release at adrenergic endings. The potential effect of these compounds as antihypertensive agents is of great interest because blood pressure reduction can be induced by a new mechanism, i.e. activation of dopaminergic receptors which results in a decrease of the renin angiotensin system or a vasodilatory action.(ABSTRACT TRUNCATED AT 250 WORDS)

Aldosterone↗
PubMed1992

Double-blind placebo-controlled trial of terazosin effect on blood pressure and urinary output of dopamine in hypertensive patients.

In a parallel, double-blind study, 12 untreated hypertensive patients received terazosin (2-4 mg/day for 4 weeks), and 12 received placebo during the same period. Systolic and diastolic blood pressure decreased significantly in the terazosin group, from 150 +/- 5.0 mmHg systolic and 99.6 +/- 2.0 diastolic before treatment, to 134.0 +/- 7.0 systolic and 85.6 +/- 3.0 mmHg diastolic at week 4 of treatment. No significant blood pressure changes occurred in the placebo group. Blood pressure decrease showed a positive correlation (r = .62 and r = .52 for systolic and diastolic blood pressure, respectively) with the patient's age (P less than .05). Total plasma cholesterol decreased 18% in the terazosin group (P less than .05) and 9% in the placebo group (P greater than .05). Urinary dopamine excretion decreased significantly from 692.8 +/- 180.0 to 330.5 +/- 52.0 micrograms/24 hours in the terazosin group (P less than .05) and showed a nonsignificant increase in the placebo group. Compared with 22 age- and sex-matched healthy volunteers, urinary dopamine excretion in the hypertensive group before treatment was not statistically different (779.3 +/- 83.1 micrograms/24 hours). Dopamine excretion was higher in untreated hypertensive men and in male healthy volunteers compared with women. The decrease of urinary dopamine excretion observed under terazosin treatment could be due to a decrease of kidney dopamine synthesis or release induced by blood pressure reduction, or secondarily to the blockade of kidney alpha 1-receptors, modulating dopamine excretion. No significant changes were observed in urinary excretion of noradrenaline and adrenaline.

Adrenergic alpha-Antagonists↗