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Biomedical subjects

M Velasco

Publications and source records attributed to M Velasco.

At least 109 records · Page 6Linked to original sources
PubMed1996

[Colonic tuberculosis as a cause of rectal bleeding in 2 patients with HIV infection].

BACKGROUND: Extrapulmonary tuberculosis is a relatively frequent disease in patients with HIV infection. This may be observed coinciding with pulmonary involvement or without diagnostic data of the same. Within extrapulmonary involvement, gastrointestinal involvement is one of the least frequently observed and its diagnosis is very difficult due to the scarce clinical suspicion because of the unspecific symptomatology. METHODS: Segmentary colonic tuberculosis was diagnosed in two patients presenting rectal bleeding. The diagnosis was neither clinically nor endoscopically suspected and only histologic and microbiologic study of the biopsies led to establishment of the diagnosis. Pulmonary involvement was also seen in one of the 2 patients. RESULTS: Medical treatment was initiated following the diagnosis. The evolution was good in one patient, while the other developed a picture of massive rectal bleeding requiring surgical resection following which the patient died due to complications. CONCLUSIONS: Colonic tuberculosis is an infrequent disease in patients with HIV infection. Only a high index of clinical suspicion along with adequate histopathologic and microbiologic study of all the colonic lesion biopsies can establish the real frequency of this disease in this group of patients.

Adult↗
PubMed1996

Aberrant crypts as a biomarker for colon cancer: evaluation of potential chemopreventive agents in the rat.

We assessed the effects of 41 potential chemopreventive agents in the F344 rat using the inhibition of carcinogen-induced aberrant crypt foci (ACF) in the colon as the measure of efficacy. ACF were induced by the carcinogen azoxymethane in F344 rats by two sequential weekly injections at a dose of 15 mg/kg. Two weeks after the last azoxymethane injection, animals were evaluated for the number of aberrant crypts detected in methylene blue-stained whole mounts of rat colon. The 41 agents were derived from a priority listing that was based on reports of chemopreventive activity in the literature and/or efficacy data from in vitro models of carcinogenesis. The list of agents included representative examples of phytochemicals, vitamins, minerals, inhibitors of proliferation, inducers of Phase 1 and Phase 2 metabolism systems, nonsteroidal anti-inflammatory agents, and differentiation agents. Eighteen agents were positive in the assay, significantly reducing the incidence of ACF at least in one of two doses tested. As a chemical class, the nonsteroidal anti-inflammatory drugs, which included ibuprofen, ketoprofen, piroxicam, and indomethacin, were most active; other less potent agents were arginine, butylated hydroxyanisole, curcumin, diallyl sulfide, difluoromethylornithine, 18 beta-glycyrrhetinic acid, indole-3-carbinol, oltipraz, purpurin, rutin, and the sodium salts of butyrate, selenite, and thiosulfate. Twenty-three agents did not inhibit ACF; included among these were several agents that promoted the development of ACF at one or both doses tested: benzyl isothiocyanate,calcium glucarate, catechin, dihydroepiandosterone, fluocinolone acetonide,folic acid, levamisole, 2-mercaptoethanesulfonic acid, nordihydroguiaretic acid, potassium glucarate, propyl gallate, beta-sitosterol, sodium cromolyn, sodium molybdate, and sulfasalazine. The aberrant crypt assay demonstrates reasonable specificity and sensitivity in predicting which agents are likely to prevent colon cancer.

Animals↗
PubMed1996

[Hepatitis E virus infection in Chile: preliminary report].

BACKGROUND: Hepatitis E virus is an enterally transmitted virus that produces an acute self limited infection. AIM: To study serum antibodies against hepatitis E virus in different patients. PATIENTS AND METHODS: Using and ELISA technique, IgG antibodies against hepatitis E virus were measured in 40 alcoholics, 40 hemophiliacs, 174 blood donors, 36 subjects with acute non A-non B-non C hepatitis and 66 subjects with acute hepatitis A. RESULTS: Antibodies were detected in one alcoholic (2.5%), 3 hemophiliacs (7.5%), 7 blood donors (4%), 3 patients with non A-non B-non C hepatitis (8.3%) and 3 patients with acute hepatitis A (4.5%). CONCLUSIONS: A low frequency of hepatitis E infection was detected in the studied subjects.

Adolescent↗
PubMed1995

Inhibition of aberrant crypt growth by non-steroidal anti-inflammatory agents and differentiation agents in the rat colon.

Aberrant crypts are aggregates of single to multiple colonic crypts evidencing hallmarks of dysplasia and may be the earliest detectable pathological lesions for colon cancer. The aberrant crypt assay has been developed in 2 protocols. In one, putative chemoprevention agents are tested for inhibitory effects when administered concomitantly with a carcinogen. In the other, the objective of this study, aberrant crypts were induced in F344 rats by parenteral injection of the colon carcinogen azoxymethane (AOM) and allowed to develop for 4 weeks, when an average of 90-100 aberrant crypt foci per colon were found in the methylene blue-stained colon. Then, during the second 4 weeks of the experiment, aberrant crypts were allowed to further develop to a frequency of > 150 foci per colon, a time when multi-crypt foci were observed. During this time we tested the inhibitory effects of 4 analgesic drugs and 2 differentiation agents for effects of aberrant crypt growth and development. We found the non-steroidal anti-inflammatory drugs piroxicam, aspirin and ibuprofen, but not acetaminophen, to be effective in suppressing aberrant crypt formation or the progression to foci of multiple aberrant crypts. Treatment with chemosuppressing agents 13-cis-retinoic acid (13-cRA) and 4-hydroxyphenretinamide (4-HPR), known differentiating agents, however, did suppress expansion of aberrant crypt foci, with 13-cRA being the much more potent agent.

Acetaminophen↗
PubMed1995

Use of serial carcinoembryonic antigen and CA 15.3 assays in detecting relapses in breast cancer patients.

UNLABELLED: To evaluate the utility of CEA and CA 15.3 for early diagnosis of recurrence, serial serum determinations of both antigens were performed in 1023 patients (follow-up: 1-10 years, mean 6.2 years) with primary breast cancer (CA 15.3 in 533 cases) and no evidence of residual disease (NED) after radical treatment (radical mastectomy or simple mastectomy and radiotherapy). 246 patients developed metastases during follow-up. RESULTS: CEA and CA 15.3 were elevated ( > 10 ng/ml or > 60 U/ml, respectively) prior to diagnosis in 40% (98/246) and 41% (37/91) of the patients with recurrence, with a lead time of 4.9 +/- 2.2 and 4.2 +/- 2.3 months, respectively. When patients with locoregional recurrences were excluded, sensitivity improved to 46% (CEA) and 54% (CA 15.3), and to 64% with both tumor markers (CEA and/or CA 15.3). Higher levels of both CEA and CA 15.3 at diagnosis of recurrence, higher sensitivity in early diagnosis of relapse, and a higher lead time were found in ER+ (CEA) or PgR+ patients (CA 15.3) than in those that were negative for these receptors in the primary tumor (p < 0.001). Specificity of the tumor markers was 99% for both CEA (777 NED patients) and for CA 15.3 (444 NED patients), respectively. In conclusion, CEA and CA 15.3 are useful tools for early diagnosis of metastases, mainly in those patients with ER+ or PR+ tumors.

Antigens, Tumor-Associated, Carbohydrate↗
PubMed1995

Electrical stimulation of the centromedian thalamic nucleus in control of seizures: long-term studies.

Five patients with chronic incapacitating seizures averaging 15-5,000/month were selected for study. All patients had more than one seizure type and had received maximal doses of antiepileptic drugs (AEDs). The centromedian thalamic nucleus (CM) was stimulated electrically through bilateral multicontact platinum electrodes stereotaxically placed in CM and connected to internalized pulse generators. Electrophysiologic confirmation of electrode position included thalamically elicited recruiting responses and EEG desynchronization recorded at the scalp. Stimulation parameters were adjusted individually in the range of 450-800-microA intensity, 65 pps, 0.09 ms, in 1-min trains, alternating right and left side stimulation and with 4-min intervals delivered for 2 h/day. Quantitative evaluation included frequency of seizures/month, number of maximal interictal paroxysmal discharges, and frequency of background activities counted in selected scalp EEG samples, taken throughout the observation period (7-33 months). Significance of changes was evaluated by parametric Student's t test. Generalized tonic-clonic seizures (GTC) decreased dramatically, almost disappearing in all cases (p < 0.001), with a significant reduction in interictal paroxysmal discharges (p < 0.01) and a tendency toward an increase in EEG background frequency. Other generalized seizures (atypical absences) decreased significantly, but there was no change in the number of complex partial seizures (CPS). CM stimulation is useful in control of GTC, but its beneficial effect on other seizure types has not been established.

Adult↗
PubMed1995

Persistence of the typical spike-wave EEG pattern after surgical excision of a temporal lobe astrocytoma and apical lobectomy.

This is a report on a patient with intractable 'primary' generalized seizures and typical spike-wave EEG patterns, in whom an unexpected temporal lobe astrocytoma was detected by MRI studies. Clinical and electrophysiological studies were performed before and after surgical excision of the tumor and apical temporal lobectomy in an attempt to determine whether 'primary' generalized seizures and EEG patterns and the temporal lobe tumor were only coincident neurological disorders or were indeed related. Before resection, the patient consistently showed a typical spike-wave EEG pattern with no background and paroxysmal activities suggestive of 'secondary' bilateral synchrony in 10 consecutive conventional EEG recordings; neither spontaneous interictal nor ictal ECoG activities suggested focal temporal lobe epileptogenesis. After resection, the patient showed increased pentylenetetrazol (PTZ) convulsive threshold, and reduction in the number of 'primary' generalized seizures, although typical spike-wave EEG discharges persisted. These observations suggest that 'primary' generalized seizures, EEG patterns and the temporal tumor were physiopathologically interrelated, and that both reticulocortical and corticoreticular mechanisms may participate together in the genesis of 'primary' generalized clinical and EEG activities.

Adult↗
PubMed1995

Dopaminergic influence on the cardiovascular response to exercise in normotensive and hypertensive subjects.

Fourteen subjects (normotensive, hypertensive) were studied at the Vargas Hospital of Caracas. They were treated with placebo (2 periods), domperidone, a peripheral dopaminergic blocker, at the daily oral dose of 40 mg, and metoclopramide, a central and peripheral dopaminergic blocker, at the daily oral dose of 40 mg. All placebo and active drug periods lasted 1 week. Cardiovascular hemodynamic parameters (blood pressure, heart rate) were measured before, during and after submitting subjects to treadmill exercise according to the Bruce's protocol. Metoclopramide decreased significantly heart rate before and during exercise stress and systolic blood pressure during stage 1 exercise in normotensive subjects. Domperidone decreased significantly heart rate before and during exercise stress, and systolic blood pressure during stage 3 exercise in hypertensive subjects. Neither heart rate nor blood pressure were changed significantly after 8 minutes resting period post exercise. Our results suggest the existence of an excitatory modulatory influence of dopaminergic influence during exercise over the sympathetic activity.

Adult↗
PubMed1995

Metoclopramide blocks bromocriptine induced antihypertensive effect in hypertensive patients.

Two groups of patients with essential hypertension were studied at the Vargas Hospital of Caracas. The first group of 9 patients under placebo treatment for 1 week received a single 2.5 mg oral dose of bromocriptine. Cardiovascular and biochemical parameters including arterial pressure, heart rate, plasma renin activity, and plasma aldosterone levels were evaluated during the 6-hour period before and after the administration of drugs. The second experimental design was as follows: 9 patients received 30 mg metoclopramide daily (divided in 3 doses) for 1 week. At the end of the period a single oral dose of 2.5 mg of bromocriptine was given to each patient. The cardiovascular and biochemical parameters were also determined. Bromocriptine reduced both systolic and diastolic arterial pressure. The peak antihypertensive effect was shown 3 hours after administration of the drug, but the reduction of arterial pressure lasted approximately 6 hours. At the same time bromocriptine reduced plasma aldosterone levels and plasma renin activity. This reduction persisted 6 hours after its administration. Metoclopramide reversed the antihypertensive effect of bromocriptine and its effect on aldosterone secretion and plasma renin activity. We conclude from these findings that bromocriptine acts as an antihypertensive agent by stimulating DA2 dopaminergic receptor, the dopaminergic receptor involved in aldosterone and renin secretion is possibly DA2.

Aldosterone↗
PubMed1995

Sleep-epilepsy interactions in patients with intractable generalized tonic seizures and depth electrodes in the centro median thalamic nucleus.

Sleep-epilepsy interactions were studied in ten patients with Lennox-Gastaut Syndrome (LGS) suffering intractable generalized tonic seizures associated with generalized ictal fast spikes and interictal slow spike-wave complexes, where electrodes were implanted in the centromedian thalamic nucleus (CM) as part of a neuroaugmentive procedure for seizure control. In these patients, continuous all night recordings according to International Guidelines were performed to quantitatively determine changes in sleep patterns produced by the epileptic condition and changes in ictal and interictal surface and CM EEG activities produced by sleep stages. LGS patients showed significantly longer wakefulness (W) and shorter slow wave sleep (SWS) II than normals. Patients with seizures during the night showed shorter latency and larger number of paradoxical sleep (PS) periods than those patients without seizures. Ictal and interictal spike-wave EEG activities appeared together in surface and CM regions during all sleep stages with a ratio SURFACE/CM almost equal to one and PS did not focalize ictal and interictal activities in thalamic or cortical regions. Occurrence and duration of "myoclonic" ictal EEG component and number of interictal spike-wave complexes were higher during SWSII while they were smaller during PS than during W.

Adult↗
PubMed1994

Micronuclei, a biomarker for chemoprevention trials: results of a randomized study in oral pre-malignancy.

Biomarkers are being sought that could serve as surrogate end points for chemoprevention trials. Micronuclei, cytoplasmic fragments of DNA, have been proposed as a biomarker and studied in oral pre-malignancy. This study evaluated micronuclei frequency in a randomized chemoprevention trial of oral pre-malignancy. A recent clinical trial evaluated the responses of pre-malignant oral lesions to 3 months of therapy with isotretinoin followed by 9 months of either low-dose isotretinoin or beta-carotene. For 57 study participants, micronuclei were counted in mucosal scrapings of the lesion and in normal-appearing mucosa at baseline and following 3 months and 12 months of therapy. Micronuclei counts were higher in scrapings from the lesion than in the normal-appearing mucosa. Following 3 months of isotretinoin, the micronuclei counts in scrapings of the lesion were significantly reduced. With treatment, the mean micronuclei count declined at 3 months. In a randomized comparison, both isotretinoin and beta-carotene maintained the suppression of micronuclei. The change in micronuclei count was not associated with the clinical or histological response to treatment. Chemoprevention treatment with isotretinoin led to a reduction in frequency of micronuclei, a marker of recent DNA injury, which was then maintained by both isotretinoin and beta-carotene.

Biomarkers, Tumor↗
PubMed1994

Dopamine-induced antihypertensive effects and plasma insulin rise are blocked by metoclopramide in labetalol-treated patients.

Eleven patients with moderate to severe hypertension were studied at the Vargas Hospital of Caracas. The patients were pretreated with labetalol, 800 to 1200 mg/day, orally, over a period of 1 week, after which an intravenous infusion of dopamine, .5 to 3 micrograms/kg/minute, was given. Two intravenous dopamine infusions (30 minutes each) were performed before and after the injection of metoclopramide (30 mg, intravenous bolus). Two washout periods were also included before and after metoclopramide administration. 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 mm Hg (P < .001) without altering heart rate, and it increased plasma insulin levels from 8.29 +/- .70 microU/mL to 12.09 +/- 1.83 microU/mL (P < .01). Metoclopramide caused no changes of blood pressure or plasma insulin levels. Hypotensive responses and plasma insulin increases due to dopamine were blocked by metoclopramide, however. The authors conclude that a dopaminergic receptor may be involved in some cardiovascular responses and in modulating insulin secretion in humans.

Blood Glucose↗
PubMed1994

Long-term effects of medical and surgical treatments on Parkinson's disease.

Three groups of patients with Parkinson's disease (PD) were studied: (1) PD patients treated medically with L-Dopa and anticholinergics, (2) PD patients treated with thalamo-subthalamotomies plus medical treatment, and (3) PD patients treated with autologous adrenal medullary transplantation to right caudate nucleus plus medical treatment. Evaluations prior and 1, 6 and 12 months after treatment were accomplished with PD scales (NYPDS, UPDS, Schwab and England and Hoehn and Yahr scales). No attempt was made to compare one PD after treatment in each group. Statistical analysis was performed with the Friedman-Anova test. Group 1 did not show significant improvement at any time but deterioration at 12 months. Group 2 showed significant improvement at 1 month but at 12 months deterioration occurred mainly in the mental condition and akinesia. Group 3 did not show significant improvement at any time but at 12 months there was a tendency of improvement in self-sufficiency.

Adrenal Medulla↗