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A Avila

Publications and source records attributed to A Avila.

At least 55 records · Page 3Linked to original sources
PubMed1996

Cholesterol sulphate-reactive autoantibodies are specifically increased in chronic chagasic human patients.

An antibody reactive with cholesterol sulphate (CS) was characterized in human sera by ELISA, erythrocyte and liposome absorption. This antibody was found evenly distributed between the IgA and IgM classes, and whilst this was present at low titres in the serum of 16% of healthy individuals studied, it was significantly elevated in 78% of Trypanosoma cruzi-infected subjects. No association was found between antibody levels and the degree of myocardial damage. No significant difference in immunoreactivity was found between healthy and chagasic subjects using dehydro-epiandrosterone sulphate and pregnenolone sulphate and cholesterol, ergosterol, lanosterol, stigmastanol, beta-stigmasterol, pregnenolone, prednisolone and dehydroepiandrosterone as antigens, suggesting that in chagasic sera the whole sterol molecule is important for optimal antibody binding. CS-reactive antibodies were easily purified by absorption either with CS-bearing liposomes or with dextran sulphate gel and further elution with 1.5 M NaCl. The optimal pH of CS-antibody interaction was 4.0 with 85% binding at pH 7.0. Polylysine strongly decreased the binding of these antibodies to the corresponding antigen. Furthermore, these antibodies were strongly absorbed by rabbit and guinea pig erythrocyte but not by rat or human erythrocyte. In contrast with anti-sulphatide antibodies, no significant increase in CS-reactive antibodies was found in dilated cardiomyopathies. Whilst CS itself was not detected in T. cruzi lipid extracts, there is an unidentified sulphated sterol, which migrates close to standard CS and which strongly binds chagasic but not control sera. This latter sterol might be acting in chagasic patients as a powerful antigen, triggering specific autoantibody production.

Animals↗
PubMed1996

Acute effects of levodopa on neuropsychological performance in stable and fluctuating Parkinson's disease patients at different levodopa plasma levels.

The contribution of dopaminergic systems to cognitive defects in Parkinson's disease and the cognitive effects of levodopa remain controversial. The levodopa plasma levels and the neuropsychological performance of 10 parkinsonian patients with a stable motor response to the drug and 10 matched parkinsonian patients with a 'wearing-off' phenomenon were studied 12 h after levodopa was withdrawn (time zero), and at 1 h and 4 h after an oral dose of levodopa (i.e. at '+1H' and '+4H'), to investigate whether discrete cognitive domains are more sensitive to levodopa in parkinsonian patients with the wearing-off phenomenon. Considering the 20 patients as a whole, levodopa significantly diminished the response time in verbal and visuospatial memory tests, the extradimensional matching test and the Wisconsin card sorting test (WCST), without significantly improving or worsening the patient's accuracy. A significant group-by-time effect was only evident in the WCST; while in stable patients levodopa produced no changes, wearing-off patients significantly reduced the number of categories achieved and had more perseverative errors at +1H, recovering at +4H. These results confirm previous findings of selective adverse effects of levodopa on highly demanding executive tasks in Parkinson's disease and additionally suggest that some previous discrepancies between studies may be accounted for by lack of differentiation between stable and wearing-off conditions. 'Frontal' disturbances on neuropsychological tests with levodopa may become evident only after massive degeneration of the dopamine systems has occurred.

Aged↗
PubMed1995

Longitudinal evolution of prefrontal leucotomy in Tourette's syndrome.

We report the case of a 69-year-old man with severe Tourette's syndrome (TS) who underwent a bilateral prefrontal leucotomy at the age of 29 years to alleviate coprolalia, copropraxia, and obsessive-compulsive disorder. No improvement was observed during the 5 years after the leucotomy. Tics and associated behavioral abnormalities disappeared thereafter, to recur at age 67. Long-term follow-up of single cases can help to estimate the role of neurosurgery in the treatment of TS.

Aged↗
PubMed1995

Abnormalities of the Bereitschaftspotential and MRI pallidal signal in non-encephalopathic cirrhotic patients.

In cirrhotic patients, even in the non-encephalopathic state, MRI may show an increased signal in globus pallidus in T1-weighted sequences, the clinical significance of which is still poorly characterized. A dysfunction of the motor circuit of the basal ganglia might be predicted if the increased MRI signal expressed alterations in the globus pallidus activity. We compared the Bereitschaftspotential (BP) in 15 non-encephalopathic cirrhotic patients and 15 age-matched controls and found that the amplitude of the early component and the peak negativity of the BP before the electromyogram onset were significantly reduced in the patient group. The intensity of the pallidal signal was related to the plasma ammonia level but the amplitudes of the BP were not related to the pallidal signal or to ammonia. These findings indicate that a defective activity of the cortical areas implicated in the preparation of movement, not specifically related to the pallidal signal, can be present in cirrhotic patients, even in the non-encephalopathic state.

Adult↗
PubMed1995

Levodopa does not aggravate postural tremor in Parkinson's disease.

Characterization of postural tremor in Parkinson's disease (PD) is incomplete. It was suggested to be an exaggerated physiological tremor and to be enhanced by the action of levodopa. We compared the magnitude of postural tremor to the magnitude of rest tremor and to plasma levodopa levels in 20 PD patients, 10 with stable motor response to oral levodopa, and 10 with the wearing-off phenomenon. Tremor assessment included motor scores of the Unified Parkinson's Disease Rating Scale and accelerometric measurements. Accelerometric data showed that the absolute power of both rest and postural basal dominant tremor frequencies significantly diminished with the increase in plasma levodopa levels and increased with their decrease. Tremor frequencies were also significantly changed by levodopa, which slowed rest tremor and increased postural tremor dominant frequency. This latter, however, did not reach the 8- to 12-Hz frequency band said to be typical of exaggerated physiological tremor. No significant differences between groups were found in their tremor response to levodopa. This study shows that the net postural tremor exhibited by PD patients is improved by levodopa, that levodopa does not augment tremor in the 8- to 12-Hz range, and that this effect is independent of the patient's motor response pattern of oral levodopa.

Aged↗
PubMed1995

Hemostatic disturbances in acute ischemic stroke: a study of 86 patients.

The relevance of coagulation abnormalities in ischemic stroke remains uncertain. The purpose of this study was to identify abnormal patterns of coagulation in established ischemic stroke. We measured coagulation parameters in 86 patients with acute ischemic stroke: 10 lacunar, 55 atherothrombotic and 21 cardioembolic. Statistical comparisons were made between different stroke groups and between all stroke patients and 60 healthy controls. A decrease in functional antithrombin III and plasminogen and an increase in thrombin-antithrombin III complexes, total protein S, tissue plasminogen activator, plasminogen activator inhibitor and D-dimer were observed in the stroke group (p < 0.05). A positive correlation was found between tissue plasminogen activator and thrombin-antithrombin III levels in cardioembolic stroke (p < 0.05). Protein C levels showed significant differences between the three groups, and in the cardioembolic group they were lower than in controls (p < 0.05). Antiphospholipid antibodies were positive in two cases. We conclude that activation of coagulation and fibrinolytic pathways was observed during the acute phase of ischemic stroke. Protein C activity is different in the three types of strokes analyzed, and higher levels seem to be associated with lacunar lesions. Antiphospholipid antibodies do not seem to play an important role in the pathogenesis of stroke in a nonselected population.

Aged↗
PubMed1995

The effects of beta 1-adrenergic blockade on the growth response to growth hormone (GH)-releasing hormone therapy in GH-deficient children.

Acute suppression of SRIH secretion with a beta-adrenergic antagonist can increase the GH response to GHRH. To determine whether chronic beta-blockade could enhance the growth-promoting effects of GHRH therapy, we conducted a double blind, placebo-controlled, randomized, cross-over trial of coadministration of the selective beta 1-antagonist atenolol together with GHRH in 11 GH-deficient children. In randomly chosen order, each patient received two 12-month treatment periods with a single daily injection of GHRH (20 micrograms/kg, sc, at bedtime), plus daily oral administration of either atenolol (1 mg/kg) or placebo. The growth velocity increased, rising from a mean +/- SD of 2.6 +/- 0.4 cm/yr before treatment to 5.4 +/- 1.0 cm/yr during the first year of treatment with GHRH plus placebo and to 6.8 +/- 1.2 cm/yr during the first year of treatment with GHRH plus atenolol. The mean growth velocity during treatment with GHRH plus atenolol was significantly greater than that observed during GHRH plus placebo (P < 0.05). After cross-over, however, during the second year of therapy, we did not observe any significant differences in growth velocity between the two groups (4.2 +/- 1.4 vs. 3.9 +/- 0.8 cm/yr during treatment with GHRH plus placebo and GHRH plus atenolol, respectively). The mean 24-h serum GH levels were 1.4 +/- 0.9 micrograms/L during the baseline period, 1.3 +/- 0.2 and 2.0 +/- 1.4 micrograms/L during the first year of GHRH plus placebo and GHRH plus atenolol, respectively (P = NS), and 2.7 +/- 1.4 and 1.4 +/- 0.4 micrograms/L during the second year of GHRH plus placebo and GHRH plus atenolol, respectively (P < 0.05). This is the first demonstration that alteration of neurotransmitter action can enhance the therapeutic response to a hypothalamic releasing factor.

Adrenergic beta-1 Receptor Antagonists↗
PubMed1995

Growth hormone (GH) responses to GH-releasing peptide and to GH-releasing hormone in GH-deficient children.

The GH-releasing peptides (GHRPs) are a family of hexa- and heptapeptides that specifically stimulate GH secretion in normal adults and children. They would be an attractive potential form of therapy for GH deficiency (GHD) if they are also active in these patients. Their action, however, appears to result at least in part through hypothalamic responses, which may be impaired in GHD, and their ability to evoke a GH response in these patients must therefore be directly examined. We studied GH responses to the heptapeptide GHRP-1 in 22 prepubertal children with previously documented GHD and growth failure and compared them to responses to GHRH and the two peptides administered together. Patients received 1 microgram/kg GHRH-(1-44)NH2, 1 microgram/kg GHRP-1, or both, in random order. Tests were separated by at least 1 week. GHRP-1 evoked a significant GH response in 60% of the patients, comparable to the 68% who responded to GHRH. The magnitudes of the peak responses were similar (7.5 +/- 8.0 micrograms/L to GHRP-1 and 11.2 +/- 12.1 to GHRH), although the duration of the GH rise was briefer after GHRP-1. Both responses were lower than those previously observed in normal subjects. There was a marked synergy in responses when the two were given together; the GH peak (34.2 +/- 44.8 micrograms/L) significantly exceeded the sum of the individual responses, and the proportion of patients who responded (86%) was also higher. Thus, despite the absence of endogenous GHRH reflexes in most patients with GHD, these children can respond to GHRP-1 similarly to GHRH, and GHRP-1 can markedly enhance the response to GHRH. These results suggest that GHRPs or their analogs could form the basis for therapy of GHD.

Adolescent↗
PubMed1995

Persistence of MRI hyperintensity of the globus pallidus in cirrhotic patients: a 2-year follow-up study.

We investigated the long-term persistence and short-term stability of globus pallidus (GP) hyperintensity on T1-weighted MRI in 19 cirrhotic patients. After a mean interval of 25.8 months, the hyperintensity of the GP persisted in 17 patients. Hyperintensity disappeared in two patients with hepatocarcinoma, indicating that hyperintensity can revert to normal in circumstances other than liver transplants. Ten patients participated in a 6-month study with repeated evaluations of GP signal intensity, plasma ammonia levels, and selected neuropsychological tests. The GP signal was fairly stable during the follow-up, and the variables considered maintained significant relationships. GP hyperintensity appears as a stable indicator of the functional status of cirrhotic patients.

Adult↗
PubMed1994

Neuroradiological features of intracranial and intraorbital meningeal haemangiopericytomas.

The neuroradiological features of six intracranial and one intraorbital haemangiopericytomas (HP) are reviewed. CT was performed before and after IV contrast medium in 5 patients. In 2 patients MRI was performed before and after contrast medium; in another, only unenhanced images were obtained. Five patients were studied by selective external and internal carotid artery angiography. Women constituted 5 of the 7 patients, and the mean age was 50.5 years, thus the sex and age distribution did not differ from that of typical meningiomas. Contrary to previous reports, calcification was present in two of the intracranial HP, and bone erosion was clearly seen in one intracranial HP and the orbital lesion. On MRI the tumours showed no differences from angioblastic meningiomas. All 6 intracranial HP were aggressive: all recurred following treatment and extracerebral metastasis occurred in one case.

Adult↗
PubMed1994

Double-blind trial of flumazenil in hemiballismus.

Three patients with hemiballismus received intravenous flumazenil and placebo in a double-blind cross-over study aimed to investigate whether an antagonistic action at the level of the GABA-benzodiazepine receptors may improve choreoballistic movements. No clinical benefit was seen.

Aged↗
PubMed1993

Inhibitory effects of sinefungin and its cyclic analog on the multiplication of Trypanosoma cruzi isolates.

Sinefungin and its cyclic analog were evaluated in vitro for activity against the multiplication of Trypanosoma cruzi. When either drug was tested for eight days on twelve T. cruzi epimastigote isolates, an 800-fold difference in drug sensitivity was found. Both drugs were trypanostatics at a concentration range from 0.1 micrograms/ml to 300 micrograms/ml. The 50% effective concentration (EC50) of sinefungin and its cyclic analog at which the growth of a given isolate was inhibited was 0.38 micrograms/ml for sinefungin and 0.31 micrograms/ml for the cyclic analog against the Ma, Marin, OPS-86, Y, and Ya isolates, and > 300 micrograms/ml for sinefungin and 217 micrograms/ml for the cyclic analog against the A-35, Bertoldo, DS, EP, ES, OPS-58, and FL isolates. Incubation of drug-sensitive isolates for more than 10 days in glucose-saline (GS) medium, but not in minimal essential medium, in the presence of a 30-fold EC50 concentration of the drug induced an increase in the drug-resistant population, which maintained this phenotype for several passages in drug-free culture medium. Growth curves were analyzed as a function of parasite inoculum; it was observed that with sinefungin-sensitive T. cruzi epimastigote isolates grown in GS medium in the presence of 10 micrograms/ml of the drug, the inhibitory effects of the drug were dependent on the initial inoculum: 1 x 10(3)-1 x 10(4) parasites/ml were strongly inhibited even after 16 days. Significant impairment of thymidine incorporation into the DNA of parasites by both drugs was observed only in drug-sensitive epimastigote isolates.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine↗