Search PubMed⌕ Search

Biomedical subjects

N Alvarez

Publications and source records attributed to N Alvarez.

At least 55 records · Page 3Linked to original sources
PubMed1985

Effect of different doses of valproic acid on the serum levels of total and free diphenylhydantoin.

In the course of a large prospective study aimed at evaluating the efficacy of Valproic Acid (VPA) in persons with intractable seizures, six patients that were on a steady dose of diphenylhydantoin (DPH) were exposed to different steady doses of VPA. The changes observed in the serum levels of total, free, and percentage of free DPH are reported here. There were no consistent changes in the serum levels of total DPH, but when serum levels of DPH, obtained before VPA was added to the therapeutic plan, were considered, it was found that the total DPH decreased in those patients with the higher baseline levels while it increased in those with the lower baseline levels. There also was an increase in the absolute total and the percentage of free DPH in most instances. The data suggested that the changes occurred soon after VPA was added and remained constant in the same patient as long as the total dose of VPA did not change. The data also suggested that VPA most probably interfered through a dual mechanism, displacement of albumin-fixed DPH, and decreased liver clearance of DPH. The interpersonal variability was such that only broad generalizations are possible. There is a need to measure free DPH in patients on VPA.

Adolescent↗
PubMed1984

Physiologic analysis of the myoclonus of Alzheimer's disease.

Ten patients with clinically diagnosed Alzheimer's disease, including three cases of trisomy 21 (Down's syndrome), developed a chronic myoclonic disorder. The technique of jerk-locked averaging of EEG activity was used to analyze the myoclonus. Seven subjects demonstrated a focal, contralateral central, negative cerebral potential antecedent to the myoclonic jerks. This EEG event differs from that previously reported to be associated with the myoclonus of subacute spongiform encephalopathy (Creutzfeldt-Jakob disease).

Aged↗
PubMed1983

Paroxysmal spike and wave activity in drowsiness in young children: its relationship to febrile convulsions.

Paroxysmal rhythmic theta waves appearing during early stages of sleep have long been recognized in the EEGs of normal children. A similar pattern with intermixed spikes appears to have a different correlation. We called this pattern 'hypnagogic paroxysmal spike wave activity' or 'hypnagogic PSW.' This investigation was designed to test whether there exists a relationship between hypnagogic PSW, febrile convulsions (FC) and age. We selected 3 cohorts of children: G-1 or normal control consisted of 94 children selected with the following criteria: complete normal neurodevelopmental examination and no personal or family history of FC, epilepsy, or other neurological disorder. They all had one EEG obtained without drug induction showing a clear sequence of awake-drowsy-sleep-arousal-awake states. G-2 or pathological control group consisted of 126 children selected at random, referred to the Division of Neurophysiology at the Children's Hospital Medical Center for any problem excluding FC. At least one EEG met the criteria mentioned above. G-3 or FC group consisted of 375 children in whom the very first seizure was associated with fever without evidence of other causes for the convulsion. All met the same EEG criteria of G-1 and G-2. The medical record of 169 children of this group (40 with hypnagogic PSW and 129 without hypnagogic PSW) were reviewed.(ABSTRACT TRUNCATED AT 250 WORDS)

Brain↗
PubMed1983

Vitamin K-dependent proteins and anticonvulsant medication.

Certain anticonvulsant drugs, especially phenytoin and phenobarbital, interfere with vitamin K metabolism as indicated by a raised serum osteocalcin level. This finding may be of importance in the pathogenesis of side effects of these medications.

Adolescent↗
PubMed1983

Attempted rapid elbow flexion movements in patients with athetosis.

Voluntary rapid elbow flexion movements were studied in 14 patients with athetosis on the basis of cerebral palsy. When the movement was attempted with one arm, other muscles inappropriate for the task, such as muscles in the opposite limb, were also activated. EMG activity of the biceps and triceps was analysed in detail, and the patterns seen in the different patients were divided into six groups: (1) The normal "ballistic" triphasic pattern, with bursts of normal duration, alternating in biceps and triceps, but the triceps might be activated first, causing the limb to extend rather than flex, (2) The triphasic pattern, with bursts of long duration, (3) Repetitive cycles of the triphasic pattern with particularly long antagonist bursts, apparently limiting the movement in each cycle, (4) Long bursts synchronous in agonist and antagonist muscles, (5) Continuous activity of the agonist, with reduction in activity of the antagonist, (6) Failure to be able to do the task. The pathophysiology of athetosis is that voluntary movement is characterised by excessive muscular activity, most prominently in inappropriate muscles, both extraneous to the task and directly antagonistic.

Adult↗
PubMed1982

Compliance for anticonvulsant medication in an institution for mentally retarded.

The compliance in a large institution for mentally retarded was evaluated using the results of the plasma levels of anticonvulsant medications that were routinely requested for the management of the patients living there. Because these tests are part of the routine work-up, the study could be done at no extra cost for the institution and no hazard for the patients involved in the study. In this particular case, the compliance for antiseizure medication was considered to be good. Once the compliance for a medication that is widely used throughout the institution is established, it is reasonable to extend the conclusions to other medications prescribed in the same place.

Adolescent↗
PubMed1978

[Intestinal amebiasis in children. I. Etiological study of colonic lesions of the rectosigmoid colon].

A total of 253 children from two months to 12 years old, who had diarrheic or dysenteric syndromes, were studied from the rectosigmoidoscopic and parasitologic points of view. In addition, 112 and 20 of these patients were also studied bacteriologically and virologically, respectively. Only in 28 patients torphozoites of Entamoeba histolytica were found by means of direct microscopic examination, staining techniques and amoebal cultures. Enteropathogenic bacteria were isolated in 41 of the 112 cases examined. No viral particles were detected in the 20 cases studied. From the discussion of these results, the conclusion is reached that the rectosigmoidal mucusal alterations which have been currently considered as suggesting amoebal lessions are not characteristic of invasive intestinal amebiasis in children.

Child↗
PubMedDate not supplied

Canadian consensus recommendations for the measurement and reporting of diastolic dysfunction by echocardiography: from the Investigators of Consensus on Diastolic Dysfunction by Echocardiography.

Abnormalities of diastolic filling are increasingly recognized as a cause of symptoms and predictors of outcome in patients with most forms of heart disease. Noninvasive assessment of diastolic filling is possible in almost all patients, but accurate evaluation must relate echocardiographic Doppler measurements to the complex physiologic and hemodynamic factors responsible for normal and abnormal filling. This evaluation has been facilitated by recent correlation of Doppler measurement of mitral and pulmonary venous inflow with hemodynamic studies. These studies have confirmed that when a careful, integrated approach is taken, Doppler flow patterns can document a progressive pattern of abnormality in many conditions. Impaired left ventricular (LV) relaxation is seen early and is recognized by a decrease in early transmitral LV filling and an increased proportion of filling during atrial contraction. As abnormalities progress, increasing LV chamber stiffness and elevated left atrial pressure lead to a "pseudonormal" filling pattern that previously has caused considerable confusion. This can be unmasked by careful evaluation of pulmonary venous inflow and the use of the Valsalva maneuver. When marked diastolic abnormalities are present, LV filling has restrictive features characterized by rapid early filling, a very stiff left ventricle with high filling pressures, and a poor prognosis. Routine measurement of indexes of diastolic filling have been hampered by uncertainty as to what should be measured, what techniques should be used, definition of normal values, and a clear method of reporting findings. This report represents the efforts of a Canadian consensus group to define a national standard for the performance and reporting of echocardiographic Doppler studies of diastolic filling.

Aged↗