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J Parra

Publications and source records attributed to J Parra.

At least 19 recordsLinked to original sources
PubMed2007

Acrylic bone cements with bismuth salicylate: Behavior in simulated physiological conditions.

In a previous work, we reported the development of acrylic bone cement formulations for application in percutaneous vertebroplasty, by using bismuth salicylate (BS) as the radiopaque agent. Our objective was to obtain high radiopacity along with a therapeutical effect produced by the release of salicylic acid in situ. To follow that study, the setting kinetics and static and dynamical mechanical properties of the BS cements were studied in simulated physiological conditions. Moreover, radiopacity after various times of immersion in saline and the wettability of the cements surfaces were determined. The study finished with the analysis of the biological response. From the results, it can be concluded that physiological conditions did not affect negatively to the cements performance, since all BS-loaded cements fulfilled the ISO standard requirements. Radiopacity of the formulations was maintained over time and cements with BS were found to be biocompatible.

Acrylates↗
PubMed2006

[Controversies and problems in the diagnosis of benign occipital epilepsies in infancy, childhood and adolescence].

AIM: To review the changes introduced by the new proposal of diagnostic scheme for people with epilepsy made by the International League Against Epilepsy in the categorization of the idiopathic occipital epilepsies of childhood and the diagnostic challenges of these disorders. DEVELOPMENT: The term occipital paroxysms has disappeared and two major forms are distinguished: one with early onset or Panayiotopoulos type, officially recognized as a syndrome, and one with late onset or Gastaut type. To these entities we have to add the recently described idiopathic photosensitive occipital lobe epilepsy, also included in the new list of syndromes. Detailed electroencephalogram investigations are crucial to reveal all the neurophysiological diagnostic aspects of these disorders. These investigations may suggest a close relationship with rolandic epilepsies. The characterization of the Panayiotopoulos' syndrome as a focal occipital epilepsy has been questioned. The limits of the idiopathic photosensitive epilepsy with other photosensitive epilepsies are not well defined yet. The variant of Gastaut might be sometimes difficult to distinguish from migraine with visual aura. Its long term prognosis is not clear yet, in part because this overlap with other entities. The persistence of seizures beyond adolescence in some patients and the development of learning disorders and mild cognitive dysfunction cast some doubts about its good prognosis. CONCLUSIONS: The characterization of the idiopathic occipital epilepsies and its relationships with other childhood epilepsies are a fascinating area of development in epileptology. Further research is necessary to define the limits of these disorders and their long-term prognosis.

Adolescent↗
PubMed2005

Removal of epileptogenic sequences from video material: the role of color.

BACKGROUND: After Pokémon viewing triggered an epidemic of seizures in Japan, many efforts have been made to design safety guidelines and systems to protect subjects with photosensitivity. The authors developed a new method based upon nonlinear diffusion techniques capable of filtering the epileptogenic content of a video sequence related to color without altering its spatial and luminance content. METHODS: The authors showed to 25 photosensitive patients (18 women, mean age: 22 years) the original Pokémon sequence and a modified one in an ABBA protocol using two television (TV) sets (100 and 50 Hz). RESULTS: Twenty-three patients had a photoparoxysmal response (PPR) according to Waltz classification with at least one of the scenes. The modified sequence triggered fewer and less severe PPRs than the original version in both TVs (p < 0.001). Original sequences elicited generalized PPRs in 56.5% of the trials for the 50 Hz TV and in 41.3% for the 100 Hz TV, whereas modified sequences elicited these responses in only 8.7% (50 Hz) and 4.3% (100 Hz TV) of the trials (p < 0.001). Sensitivity to the modified version on the 50 Hz TV correlated with pattern sensitivity (p < 0.05). CONCLUSION: Specific manipulations of the color modulation-depth could be enough to decrease dramatically the risk of triggering seizures in susceptible subjects exposed to provocative visual scenes. This new method can be implemented in protective devices able to filter out the epileptogenic video sequences in which color plays a fundamental role while leaving intact the spatial content, frequency, and average luminance.

Adolescent↗
PubMed2004

Electrical brain-stimulation paradigm for estimating the seizure onset site and the time to ictal transition in temporal lobe epilepsy.

OBJECTIVE: To explore and validate a novel stimulation and analysis paradigm proposed to monitor spatial distribution and temporal changes of the excitability state in patients with temporal lobe epilepsy (TLE). METHODS: We use intermittent pulse stimulation in the frequency range 10-20Hz. A quantitative measure of spectral phase de-modulation, the relative phase clustering index (rPCI) was applied to the evoked EEG signals, measured from electrodes implanted in the hippocampal formation. RESULTS: We found that in the interictal periods, high values of rPCI recorded from specific sites were correlated with the most probable seizure onset sites (SOS). Furthermore we found that high values of rPCI from certain locations correlated with shorter time intervals to the next seizure. CONCLUSIONS: Our clinical findings indicate that although the precise moment of ictal transitions is in general unpredictable, it may be possible to estimate the probability of occurrence of some epileptic seizures. SIGNIFICANCE: The use of the rPCI for probabilistic forecasting of upcoming epileptic seizures is warranted. rPCI measurements may be used to guide interventions with the aim of modifying local tissue excitability that ultimately might prevent ictal transitions.

Brain Mapping↗
PubMed2003

A new successful therapy for fetal chylothorax by intrapleural injection of maternal blood.

We present two cases of fetal chylothorax and hydrops diagnosed at 20 weeks' gestation, both of which underwent successful intrauterine treatment. In Case 1, a transient, near total resolution began 2 weeks after an iatrogenic hemothorax following a second thoracocentesis performed at 24 + 6 weeks. Because of pleural fluid reaccumulation, a Cesarean section was performed at 36 weeks. The 3805-g female neonate was admitted to neonatal intensive care but was discharged 50 days later in a healthy condition. In Case 2, resolution occurred after a third thoracocentesis and a second pleural injection of maternal blood, performed at 26 weeks. A 2660-g female neonate was delivered vaginally at 38 weeks. The infant remained asymptomatic and was discharged aged 4 days. Our experience suggests a possible useful role of intrapleural blood injection for the treatment of fetal chylothorax.

Adult↗
PubMed2003

Gamma-band phase clustering and photosensitivity: is there an underlying mechanism common to photosensitive epilepsy and visual perception?

Photosensitive epilepsy (PSE) is the most common form of human reflex epilepsy, appearing in up to 10% of epileptic children. It also offers a highly reproducible model to investigate whether changes in neuronal activity preceding the transition to an epileptic photoparoxysmal response (PPR) may be detected. We studied 10 patients with idiopathic PSE (eight female, mean age 26 years, range 9-51 years) using magnetoencephalography. In addition, we also studied the responses of five normal controls (mean age 24 years, age range 9-35 years) and three non-photosensitive epileptic patients (mean age 10 years, range 8-11 years). Spectral analysis of the MEG signals recorded during intermittent photic stimulation revealed relevant information in the phase spectrum. To quantify this effect, we introduced a second order response feature of the stimulus-triggered visual response preceding the PPR: the phase clustering index, which measures how close the phases of successive periods are grouped for each frequency component for all periods of the stimuli applied. We recorded a total of 86 PPRs, including several absence seizures, in nine of the 10 patients. We found that an enhancement of phase synchrony in the gamma-band (30-120 Hz), harmonically related to the frequency of stimulation, preceded the stimulation trials that evolved into PPRs, and differed significantly from that encountered in trials not followed by PPR or in control subjects. This novel finding leads us to postulate that a pathological deviation of normally occurring synchronization of gamma oscillations, underlying perceptional processes, mediates the epileptic transition in PSE.

Adolescent↗
PubMed2002

Efficacy of stratum corneum lipid supplementation on human skin.

Recent studies suggest that supplementing intercellular lipids of the stratum corneum in ageing populations or in people with dry skin can stimulate the functioning of the skin. This work lends support to the reinforcement capacity of two different stratum corneum lipid mixtures (synthetic stratum corneum lipid mixtures, SSCL, and internal wool lipid extracts, IWL) formulated as liposomes on healthy skin of two differently aged groups of individuals. Protection of healthy skin against detergent-induced dermatitis was evaluated. Transepidermal water loss and capacitance were used to evaluate the effect of these formulations in in vivo long-term studies. Increase in water-holding capacity is obtained only when the formulations applied are structured as liposomes. This is slightly more pronounced for aged skin. Subsequent SLS exposure reflected the protection of healthy human skin against detergent-induced dermatitis. Slightly better results were obtained with IWL containing a mixture of natural ceramides than with SSCL with only one ceramide present in the formulation. All these results support the beneficial effects of skin lipid supplementation given their resemblance to the lipids in the stratum corneum both in composition and in the structuring of the formulation.

Adult↗
PubMed2002

Prenatal diagnosis for risk of spinal muscular atrophy.

OBJECTIVES: Prenatal diagnosis of spinal muscular atrophy is usually performed in high risk couples by detection of a homozygous deletion in the survival motor neurone gene (SMN1). However, other relatives at risk of being carriers very often request genetic counselling and the possibility of prenatal diagnosis. The aim of this study was to validate a SMN1 gene quantitative test to help the couples formed by one spinal muscular atrophy carrier and a partner of the general population (1/200 potential risk) to achieve a less ambiguous risk result for the pregnancy. DESIGN: Spinal muscular atrophy carrier studies in at-risk individuals. SETTING: Department of Genetics and Gynaecology and Obstetrics in a large university hospital. POPULATION: Seventy-nine obligate carriers (more than one affected child with deletion in the offspring) and 58 non-carriers (relatives of spinal muscular atrophy families defined by marker studies) were tested to set up a quantitative analysis. The method was applied in different situations in 126 members from 34 families with spinal muscular atrophy patients. METHODS: DNA studies of the SMNI gene by marker analysis and quantitative assay. MAIN OUTCOME MEASURES: To determine double (non-carrier) or single dose (carrier) of exon 7 of the SMN1 gene in relatives of spinal muscular atrophy patients. Bayesian calculation of risk. RESULTS: The sensitivity and specificity of the method were 96% and 100%, respectively. Studies on different couples with an a priori risk of 1/200 allowed us to reduce the final risk to 1/5000 or to increase it to 1/4. CONCLUSIONS: The quantitative method can be used to achieve a less ambiguous risk in pregnancies with a 1/200 risk and in families where no sample is available to study the index case. Screening of gamete donors when the recipient is a known carrier should also be considered.

Cyclic AMP Response Element-Binding Protein↗
PubMed2001

Ring chromosome 20 epilepsy syndrome in children: electroclinical features.

Ring chromosome 20 mosaicism is associated with dysmorphic features, mental retardation, and intractable seizures, including recurrent episodes of nonconvulsive status epilepticus. The authors' findings in four children, all without dysmorphic features, indicate that mental deterioration and frequent subtle nocturnal frontal lobe seizures, associated with a characteristic EEG pattern, represent prominent additional clinical features not previously described in this syndrome. This emphasizes the importance of full-night video-EEG in children with frontal lobe seizures and cognitive deterioration.

Adolescent↗
PubMed2001

Prevalence of epilepsy in northeast Madrid.

During a period of 42 months, we studied the prevalence of epilepsy in a specific health district, composing by four towns with 98,405 inhabitants older than 10 years. This has been accomplished by a two-phase cross-sectional study. The prevalence rate observed was 4.12/1000 inhabitants for all types of epilepsy. No significant differences were found between the sexes. Sixty-three per cent of affected individuals had partial seizures, with a confirmed cause in 45%. Fifty-five patients with single unprovoked seizures, were also identified but not included in the prevalence rate.

Adolescent↗
PubMed2001

Changes of skeletal muscle proteases activities during a chronic low-frequency stimulation period.

Modifications of muscular contractile patterns by chronic low-frequency stimulation induce structural, physiological, and biochemical transformations in fast-twitch fibers that cause them to act like slow-twitch muscle. During this transformation many changes in protein pattern appear and the proteolytic system may be involved in those changes. The activities of cathepsin L, B, H, D, the level of cystatin, as well as the calpain activity in rabbit fast-twitch muscle have been compared with those of slow-twitch muscle. The results show that fast-twitch muscle has lower cathepsin activities and higher calpain activities than slow-twitch muscle. Chronic low-frequency stimulation was applied for 24 days to fast-twitch muscles and changes in proteases and protease inhibitors (cystatin and calpastatin) were studied. After 7-14 days of stimulation, lysosomal cathepsin L, B, and D and cytoplasm calpain and proteosome activities increased several-fold. Involvement of the phagocyte cells in the protein fiber turnover was minimal. Although the turnover of contractile proteins during muscle electrostimulation takes place in synchrony with changes in the muscle proteolytic system, the stimulation period used did not attain the total transformation from fast- to slow-twitch muscle proteolytic pattern.

Acid Phosphatase↗
PubMed2001

Classification of epileptic seizures: a comparison of two systems.

PURPOSE: Extensive experience with video-EEG seizure monitoring, notably in the setting of epilepsy surgery programs, has exposed the limited value of the current International Classification of Epileptic Seizures (ICES) for providing relevant localizing information. To overcome this limitation, a Semiologic Seizure Classification (SSC) has recently been proposed. This study aimed to assess and to compare the usefulness and reliability of both systems in the setting of a tertiary epilepsy center. METHODS: Three epileptologists independently reviewed video-taped seizures, randomly selected from the archive of the Epilepsy Monitoring Unit. They were blinded to the EEG findings and final diagnosis and classified all seizures according to both classifications. RESULTS: One hundred thirty-eight seizures from 60 patients (age range, 2-59 years) were reviewed (maximum, three seizures per patient). Fifty-five seizures from 20 patients were recorded in the setting of presurgical evaluations, and the remainder as part of regular diagnostic evaluations. The average interobserver agreement was higher for SSC (63.3%, kappa = 0. 56) than for ICES (38.6%, kappa = 0.41). Some categories of SSC, such as hypermotor or automotor, had the best interobserver agreement, and were strongly correlated with the anatomic localization of the seizures (frontal and temporal lobe, respectively). All reviewers agreed that SSC provided a better description of the seizures than did ICES, in 60% of the patients. CONCLUSIONS: SSC provides a more comprehensive picture of epileptic seizures than does ICES, notably in patients with localized epilepsy syndromes, and appears to be very useful and reliable, particularly in the setting of specialized epilepsy centers.

Adolescent↗
PubMed2001

Carotid endarterectomy in women: challenging the results from ACAS and NASCET.

OBJECTIVE: To evaluate and compare the short- and long-term outcomes in female and male patients after carotid endarterectomy (CEA). SUMMARY BACKGROUND DATA: Randomized carotid trials have clearly shown the benefits of CEA in specific symptomatic and asymptomatic patients. However, the short- and long-term benefits in women appear to be less clear, and the role of CEA among women with carotid disease remains uncertain. METHODS: During a 21-year period, 1,204 CEAs were performed, 464 (39%) in women and 739 (61%) in men. Complete follow-up was available in 70% of patients. RESULTS: Women were less likely to have evidence of coronary artery disease, were more likely to be hypertensive, and had a significantly greater incidence of diabetes. The mean age at CEA was 68.5 +/- 9.5 years for women and 68.0 +/- 8.5 years for men. There were no significant differences in the use of shunts, patching, tacking sutures, or severity of carotid stenoses between men and women. Surgical death rates were nearly identical for asymptomatic and symptomatic patients. Perioperative stroke rates were similar for asymptomatic and symptomatic patients. Life-table stroke-free rates at 1, 5, and 8 years were similar for asymptomatic women and men and symptomatic women and men. Long-term survival rates at 1, 5, and 8 years were higher for asymptomatic women compared with men and for symptomatic women compared with men. As a result, stroke-free survival rates at these follow-up intervals were greater for asymptomatic women compared with men, and for symptomatic women compared to men. CONCLUSIONS: The results from this study challenge the conclusions from the Asymptomatic Carotid Endarterectomy Study and the North American Symptomatic Carotid Endarterectomy Trial regarding the benefits of CEA in women. Female gender did not adversely affect early or late survival, stroke-free, or stroke-free death rates after CEA. The authors conclude that CEA can be performed safely in women with asymptomatic and symptomatic carotid artery disease, and physicians should expect comparable benefits and outcomes in women and men undergoing CEA.

Age Distribution↗
PubMed2000

Mechanism of mifepristone-induced spasmolytic effect on isolated rat uterus.

Mifepristone, a synthetic 19-norsteroid, relaxed the KCl-induced tonic contraction in isolated rat uterus in a concentration-dependent way and CaCl2 (0.1 to 10 mM) counteracted it. This effect was similar to other steroids although the mechanisms involved are unclear. Before adding the contracturant, tissue was incubated with actinomycin D (10 microM), cycloheximide (300 microM), TPCK (3 and 10 microM), Rp-cAMPS (30 microM), DDA (100 microM) and H-7 (1 microM). None of these modified the relaxing effect of mifepristone. Incubation with drugs that interfere with cGMP such as a nucleotide analogue DDG (100 microM), a soluble guanylyl cyclase inhibitor ODQ (1 microM) and an inhibitor of protein kinase G 8pCPTcGMPS (1 microM) significantly modified the effect of mifepristone, increasing its IC50.

Animals↗
PubMed2000

A short training programme for the rapid improvement of both aerobic and anaerobic metabolism.

The aim of this study was to evaluate the changes in aerobic and anaerobic metabolism produced by a newly devised short training programme. Five young male volunteers trained daily for 2 weeks on a cycle ergometer. Sessions consisted of 15-s all-out repetitions with 45-s rest periods, plus 30-s all-out repetitions with 12-min rest periods. The number of repetitions was gradually increased up to a maximum of seven. Biopsy samples of the vastus lateralis muscle were taken before and after training. Performance changes were evaluated by two tests, a 30-s all-out test and a maximal progressive test. Significant increases in phosphocreatine (31%) and glycogen (32%) were found at the end of training. In addition, a significant increase was observed in the muscle activity of creatine kinase (44%), phosphofructokinase (106%), lactate dehydrogenase (45%), 3-hydroxy-acyl-CoA dehydrogenase (60%) and citrate synthase (38%). After training, performance of the 30-s all-out test did not increase significantly, while in the maximal progressive test, the maximum oxygen consumption increased from mean (SD) 57.3 (2.6) ml x min(-1) x kg(-1) to 63.8 (3.0) ml min(-1) x kg(-1), and the maximum load from 300 (11) W to 330 (21) W; all changes were significant. In conclusion, this new protocol, which utilises short durations, high loads and long recovery periods, seems to be an effective programme for improving the enzymatic activities of the energetic pathways in a short period of time.

Adult↗