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Biomedical subjects

J Parra

Publications and source records attributed to J Parra.

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

[Relationship between primary care and neurological care].

The problems posed by health care are related to health service structure and development. The transformation of a three level care structure into one of just two levels, primary care and specialized care, plays its part. With the aim of analyzing the importance these factors might have in present-day health care, we carried out an aleatoric study of all those patients who attended our neurological service in the years 1992 and 1993. We obtained two sample groups consisting of 921 and 849 patients respectively through interconsultatory requests from practitioners within a limited health care area. We studied the patient's background, the requesting practitioner, diagnosis obtained and complementary tests used. Patients from individual practitioners varied in number from 4 to 38, with some 20% of all patients having been referred by just six practitioners. 20% of the patients we studied showed no neurological pathology. Complementary tests used in all diagnoses sent to us amounted to less than half the number of patients studied. We analyzed the importance these factors have in the present delay in health care services.

Brain Diseases↗
PubMed1995

Effects of low-frequency stimulation on soluble and structure-bound activities of hexokinase and phosphofructokinase in rat fast-twitch muscle.

Several glycolytic enzymes exist in muscle as free and structure-bound forms. A fraction of hexokinase (HK) is associated with the outer mitochondrial membrane. Phosphofructokinase (PFK) and aldolase (ALD) bind to F-actin, and AMP deaminase (AMPase) interacts with myosin. Using low-frequency stimulation (10 Hz, 24 h/d), we studied in rat fast-twitch muscle effects of contractile activity on soluble and structure-bound forms of these enzymes. Phosphoglucose isomerase (PGI), a soluble enzyme, was also examined. Fractional extraction was applied to study the intracellular distribution of soluble and bound enzyme activities 5 min, 1 h, 3 h, 1 d, and 7 d after the onset of stimulation. Confirming previous findings, total HK activity increased 7-fold in 7-d-stimulated muscles, whereas PFK, ALD, and PGI were reduced, ranging between 55% and 80% of their normal activities. AMPase activity was unaltered. At the time points studied, no changes were found in the extraction behavior of PGI and AMPase. The fraction of bound ALD increased slightly (12%). However, the distribution of HK and PFK was markedly altered. Bound PFK increased from 50% in the control to 85% in 7-d-stimulated muscles. Bound HK rose from 52% to 83% during the same time period. The increase in PFK binding was steep and occurred mainly within the first minutes and hours. The increase in HK binding occurred with some delay, but was significant in muscles stimulated for more than 1 h. In view of the altered kinetic properties of F-actin-bound PFK (alleviated allosteric inhibition by ATP) and bound HK (elevated catalytic activity), these changes are interpreted as early responses to match the metabolic demands during maximal contractile activity imposed on a muscle not programmed for sustained activity: Enhanced binding of PFK serves to accelerate glycolytic flux immediately after the onset of stimulation, whereas mitochondrial binding of HK facilitates the phosphorylation of exogenous glucose when glycogen stores have been depleted.

Animals↗
PubMed1995

Association between the oxidative polymorphism and early onset of Parkinson's disease.

The frequency of five cytochrome P450IID6 allelic variants was studied in deoxyribonucleic acid from 123 patients with Parkinson's disease and 150 healthy volunteers. This was achieved by the use of mutation-specific polymerase chain reaction and restriction fragment length polymorphism. The analyses of the CYP2D6 genotype revealed no evidence for a higher prevalence of poor metabolizers among patients with Parkinson's disease. However, increased frequency of patients with Parkinson's disease with the genotype CYP2D6wt/CYP2D6B was observed. This is attributable exclusively to subjects with early onset of the disease (28 to 49 years), with a relative risk ratio of 4.16 (95% confidence limits, 2.0 to 8.3; p < 0.0005). The subjects who had late-onset Parkinson's disease (> or = 50 years) had genotypes and CYP2D6 allele frequencies similar to the healthy subjects. This indicates that the oxidative polymorphism is related to early-onset but not to late-onset Parkinson's disease. A different influence of CYP2D6 genotype on the risk of development of Parkinson's disease is observed in Spaniards, compared with previous findings in British subjects. These results suggest the combined effect of environmental toxins and CYP2D6 in the cause of Parkinson's disease.

Adult↗
PubMed1993

Responses of fatigable and fatigue-resistant fibres of rabbit muscle to low-frequency stimulation.

This study investigates early adaptive responses of fast-twitch muscle to increased contractile activity by low-frequency stimulation. Changes in metabolite levels and activities of regulatory enzymes of carbohydrate metabolism were investigated in rabbit tibialis anterior muscle after 24 h of stimulation. In addition, changes elicited during a 5-min lasting acute stimulation experiment were compared between 24-h-prestimulated and contralateral control muscles. Stimulation for 5 min reduced energy-rich phosphates and glycogen, and increased lactate in the control muscle. A transient elevation of fructose 2,6-bisphosphate demonstrated that activation of phosphofructokinase 2 was an immediate response to contractile activity. Prestimulated muscles displayed nearly normal values for ATP, phosphocreatine and glycogen, and did not augment lactate. Increased activities of hexokinase and phosphofructokinase 2 and permanently elevated levels of fructose 2,6-bisphosphate pointed to enhanced glycolysis with glucose as the main fuel in the prestimulated muscle. Isometric tension of the control muscle decreased rapidly a few minutes after the onset of stimulation. In the prestimulated muscles, tension was almost stable, but amounted to only 30%-40% of the initial tension of the control muscle. In view of the fibre type distribution of rabbit tibialis anterior, these findings suggested that a large fibre fraction of the prestimulated muscle, possibly the glycolytic type IID fibres, did not contract. Therefore, the possibility must be considered that the metabolite pattern of the 24-h-stimulated muscle primarily reflected metabolic activities of the contracting, less fatigable fibres, most likely type IIA and type I fibres.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗
PubMed1990

[Prenatal diagnosis of myotonic dystrophy: the first experience in Spain].

We report the first prenatal diagnosis of myotonic dystrophy (MD) in Spain by DNA techniques. The previous familiar study allowed us to determine the DM haplotype in this family with the following probe/enzyme combinations: p4.1/Msp I, LDR 152/Bgl II, Apo CII/Ban I, Taq I, Bam HI, pSCII/Bgl I. In the tenth week of amenorrhea, a transabdominal biopsy was done to obtain chorionic villi. One part of the sample was processed for the cytogenetic analysis that revealed a 46 XY karyotype. The other part was used to perform the molecular analysis with two probes, p4.1 and LDR 152, determining that the fetus was a DM gene carrier with a 96% probability.

Family Health↗
PubMed1979

Renin, cortisol, and aldosterone during transcendental meditation.

The effects of transcendental meditation (TM) on plasma renin activity (PRA) and plasma concentrations of aldosterone, cortisol, and lactate were studied by measuring these variables before, during, and after 20--30 min of meditation. Subjects, who rested quietly rather than meditating, served as controls. There were no differences in the basal values for these variables between meditators and controls, but controls, in contrast to meditators, showed a significant increase in cortisol between the first (A) and second (B) samples of the control period. PRA increased slightly (14%) but significantly (p less than 0.03) during TM, but not during quiet rest in controls. Cortisol decreased progressively (after sample B) throughout the experiment to the same degree in both groups. Aldosterone and lactate did not change. The data do not support the hypothesis that TM induces a unique state characterized by decreased sympathetic activity or release from stress, but do suggest that meditators may be less responsive to an acute stress.

Adult↗
PubMed1979

Diurnal variations in unconjugated and total plasma estriol levels in late normal pregnancy.

Diurnal variations in plasma unconjugated and total estriol were assessed in 11 third-trimester subjects with uncomplicated pregnancies. Commercially available 125I-labeled radioimmunoassay kits were used. Total plasma estriols reach a nadir during the hours of sleep (400 and 700 hours) which exceeds the episodic fluctuations seen from day to day or during a given 90-minute period. Plasma unconjugated estriol fluctuations over 24 hours did not significantly exceed our previously reported episodic fluctuation of 15.6 +/- 8.2%. The data are interpreted as showing no circadian rhythm, but reflecting, in the case of total plasma estriols, an effect of improved renal clearance during hours of rest. Plasma unconjugated estriol emerges as the test of choice in the monitoring of high-risk pregnancies.

Adult↗
PubMedDate not supplied

Enhanced tumor metastases upon drug delivery in cross-linked albumin beads.

Growth of the murine hepatoma H6 was significantly suppressed by amiloride, a sodium influx inhibitor. Primary tumor growth inhibition was augmented by loading the drug into cross-linked albumin carriers, but lung metastases were enhanced. These results emphasize the importance of using metastatic tumor models when testing new drugs and/or alternative modes of drug delivery.

Albumins↗
PubMedDate not supplied

[Value of the ictal video EEG recording in the presurgical evaluation of temporal lobe epilepsy. Semiology and EEG patterns].

INTRODUCTION: The surgical treatment of epilepsy has gained increased acceptance in the last decade, especially for temporal lobe seizures. Its success is based upon a strict selection of the candidates, which combines clinical, neurophysiological, neuropsychological and neuroimaging criteria. DEVELOPMENT: The video-EEG recording of the seizures still plays an important role in this selection process, as it provides enough amount of interictal activity, demonstrates the existence of different seizure types and enables to perform an adequate electroclinical correlation. It also helps recognizing patients with concomitant non-epileptic events. The widespread use of ictal video-EEG has allowed the validation of several clinical signs, such as the dystonic posturing of the limb or the postictal speech disturbance among others, as being quite useful in the process of localization and lateralization. In fact, with the proper analysis of the ictal behavior it is possible to achieve confident lateralizing information in the majority of patients with temporal lobe epilepsy. CONCLUSIONS: This knowledge, gathered through the analysis of the semiology is complementary to that obtained with the simultaneous recording of the EEG. When a meaningful electroclinical correlation is possible, and it is also concordant with the data provided by the MRI and neuropsychological testing, a surgical procedure can be warranted without the use of intracranial electrodes.

Electroencephalography↗
PubMedDate not supplied

[The validity of the classification criteria of the International Headache Society for migraine, episodic tension headache and chronic tension headache].

INTRODUCTION: We analysed the value of the diagnostic criteria of the International Headache Society (IHS) for the classification of the primary headaches in a headache clinic. PATIENTS AND METHODS: The IHS criteria were applied to classify 208 headaches in 194 patients. Forty-two had migraine, 18 tension type headache and 76 chronic daily headaches (CDH). RESULTS: The value of IHS criteria in order to distinguish migraine from tension type headache have a specificity of 94% and a predictive positive value of 99%. The predictive negative value is 63%. The more specific symptoms for migraine were severity, photophobia, phonofobia and vomits. IHS criteria for chronic tension type headache have a very low sensibility; only the 45% of these headaches meet criteria. If we applied the criteria of Silberstein et al we can see that, without the patient history, symptoms don't distinguish between chronic tension type headache, transformed migraine and new daily persistent headache. The most specific features for distinguishing the transformed migraine were worsening with activity, vomiting and pulsating. A 62% of the CDH have analgesic overuse. CONCLUSIONS: IHS criteria distinguish accurately between migraine and tension type headache. Symptoms do not differenciate the different kinds of CDH.

Chronic Disease↗
PubMedDate not supplied

[Vascular hemichorea: clinical-radiological correlation].

INTRODUCTION: Hemichorea is uncommon in acute cerebrovascular accidents. Its appearance is in relation to the contralateral involvement of the basal ganglia, particularly the striate ganglion. With current neuroimaging techniques it is possible to identify the lesions responsible for these abnormal movements. Magnetic resonance (MR) is the technique of choice for detection of small sized lesions. OBJECTIVE: We have analysed our series of patients to try to relate the site of the lesion to the appearance of chorea. PATIENTS AND METHODS: We made a retrospective study of the cases of hemichorea of vascular origin admitted between January 1993 and April 1999. In all cases, cerebral CAT and/or MR had been done to find the site of the lesion. RESULTS: A total of 10 patients with an average age of 72.5 years (range: 55-85) was found. In eight of them (80%) lesions were found in the basal ganglia, half of which were of ischemic type and the other half hemorrhagic. The sites were: caudate nucleus in one case (10%), thalamus in two cases (20%) and capsulo-lenticular lesions in five cases (50%). All lesions were contralateral to the side of the body affected except in one case with a left thalamic haematoma and homolateral hemichorea. CONCLUSIONS: The lesions found were very varied in site. In 20% of the cases they were not detected by conventional neuroimaging techniques. This fact supports the concept of a functional global network of the basal ganglia which may be interrupted at several points and lead to the same clinical findings.

Aged↗