[The electroencephalogram: a complementary test that should not be forgotten to perform before a first seizure]. / El electroencefalograma: una prueba complementaria que no debe olvidarse realizar ante una primera crisis epiléptica.

TITLE: El electroencefalograma: una prueba complementaria que no debe olvidarse realizar ante una primera crisis epiléptica.

[Electroencephalographic alterations in children with attention deficit hyperactivity disorder]. / Alteraciones electroencefalograficas en ni os con trastorno por deficit de atencion con hiperactividad.

INTRODUCTION: Attention deficit hyperactivity disorder (ADHD) is a syndrome that affects between 3 5% of the population of school aged children, and may be accompanied by learning, language, behavioural or motor disorders. Although various electroencephalographic alterations have been described in these patients, their pathological significance has not been determined. There have also been reports of children with neuropsychological and language disorders having epileptiform anomalies in the EEG recording. PATIENTS AND METHODS: We conducted a study of 15 children, with no history of seizures, who had been referred to Child Neurology for treatment and who satisfied the criteria for ADHD according to the DSM IV and the ADHRS (attention deficit/hyperactivity rating scale). RESULTS: The EEG recording in the waking state showed significant anomalies in two of our patients (acute spike and wave paroxysmal activity in the left temporoparietal region and spike wave discharges during hyperventilation). The polysomnographic study revealed specific alterations in four children. There was a continuous spike wave trace during slow sleep (CSWS) in one case, paroxysmal activity (slow acute waves, spikes) in the temporoparietal region with secondary generalization or transmission (two cases), and frequent generalized paroxysmal discharges of slow acute waves in all phases of sleep (one case). CONCLUSIONS: The neurophysiological disorders observed in some of our patients could make it necessary to consider performing a night time polysomnographic study in certain cases of ADHD.

Alteraciones electroencefalográficas en niños con trastorno por déficit de atención con hiperactividad / Electroencephalographic alterations in children with attention deficit hyperactivity disorder

Introducción. El trastorno por déficit de atención con hiperactividad (TDAH) es una entidad nosológica que afecta al 3-5 por ciento de la población infantil en edad escolar, y puede ir acompañada de trastornos de aprendizaje, de lenguaje, conductuales o motores. Aunque se han descrito diversas alteraciones electroencefalográficas en estos pacientes, no se ha determinado su significación patológica. Por otro lado, se ha referido que los niños con trastornos neuropsicológicos y del lenguaje pueden tener anomalías epileptiformes en el EEG. Pacientes y métodos. Se han estudiado 15 pacientes remitidos a la consulta de Neurología infantil, sin antecedentes de crisis convulsivas, que cumplían los criterios del TDAH según el DSM-IV y la EDAH (escala de déficit de atención con hiperactividad). Resultados. El EEG en vigilia mostró anomalías significativas en dos de nuestros pacientes (actividad paroxística de puntas y ondas agudas en la región temporoparietal izquierda y descargas de punta-onda durante la hiperventilación). En el registro polisomnográfico observamos alteraciones específicas en cuatro niños: un trazado de punta-onda continua durante el sueño lento (POCS) en un caso; actividad paroxística (puntasondas agudas y lentas) en la zona parietotemporal con transmisión o generalización secundaria (dos casos), y frecuentes descargas paroxísticas generalizadas de ondas lentas y agudas en todas las fases del sueño (un caso). Conclusión. Las alteraciones neurofisiológicas observadas en algunos de nuestros pacientes podrían plantear la necesidad de realizar una polisomnografía nocturna en determinados casos de TDAH (AU)

Introduction. Attention deficit hyperactivity disorder (ADHD) is a syndrome that affects between 3-5% of the population of school-aged children, and may be accompanied by learning, language, behavioural or motor disorders. Although various electroencephalographic alterations have been described in these patients, their pathological significance has not been determined. There have also been reports of children with neuropsychological and language disorders having epileptiform anomalies in the EEG recording. Patients and methods. We conducted a study of 15 children, with no history of seizures, who had been referred to Child Neurology for treatment and who satisfied the criteria for ADHD according to the DSM-IV and the ADHRS (attention deficit/ hyperactivity rating scale). Results. The EEG recording in the waking state showed significant anomalies in two of our patients (acute spike and wave paroxysmal activity in the left temporoparietal region and spike-wave discharges during hyperventilation). The polysomnographic study revealed specific alterations in four children. There was a continuous spike-wave trace during slow sleep (CSWS) in one case, paroxysmal activity (slow acute waves, spikes) in the temporoparietal region with secondary generalization or transmission (two cases), and frequent generalized paroxysmal discharges of slow acute waves in all phases of sleep (one case). Conclusions. The neurophysiological disorders observed in some of our patients could make it necessary to consider performing a night-time polysomnographic study in certain cases of ADHD (AU)

A review of the collaborative exercises on DNA typing of the Spanish and Portuguese ISFH Working Group. International Society for Forensic Haemogenetics.

Since 1992 the Spanish and Portuguese Working Group (GEP) of the International Society for Forensic Haemogenetics (ISFH) has been organizing collaborative exercises on DNA profiling with the aim of making progress on standardization and discussing technical and statistical problems in DNA analysis. A total of four exercises (GEP-92 to GEP-95) have been carried out until now. A consequence of these exercises was the creation of a quality control programme in Spain and Portugal in 1995 which was carried out simultaneously with the GEP-95 exercise. The number of participating laboratories increased from 10 in the first exercise (GEP-92) to 19 in the last exercise (GEP-95). Despite this increasing number of participating laboratories, results remained satisfactory. In the last exercises, all the laboratories used PCR-based DNA polymorphisms with an increasing number of markers obtaining good results. SLPs were used by only 30% of laboratories in the last two exercises but the results indicated a good level of expertise in most of these laboratories. The reasons for these successful results are the common use of the EDNAP protocol for SLP analysis and commercially available kits or common sequenced allelic ladders for PCR-based DNA polymorphisms.

Semiparametric approach to match probability calculations using single locus probes.

A semiparametric approach to match probability calculations using single locus probes has been developed and compared graphically with other standard methods by a one-sample simulation. The density functions obtained using this method are closer to the real distributions than those obtained by conventional approaches. Our method does not need to establish an arbitrary match threshold, which has been a source of problems in practical applications of standard methods. Moreover, it can be adjusted to any particular conditions by setting the experimental error and correlation of each laboratory. To assess the practical performance of this method we carried out a comparison experiment using a sample of 229 individuals analysed in duplicate.

Allele frequency distribution of four PCR-amplified loci in the Spanish population.

The allele frequency distributions of four VNTR loci amplified by PCR have been studied in a population of 205 individuals from Spain. The loci analysed are D1S80 and three STRs: HUMTH01, HUMFES/FPS and HUMACTBF2 (SE33). The former was visualized in Metaphor agarose gels, and the STRs in sequencing polyacrylamide gels under denaturing conditions which could separate alleles with differences of a single base. This is of particular importance in the HUMTH01 locus, a tetrameric STR in which two alleles (9.3 and 10) were detected differing in a single base. Furthermore, HUMACTBP2 has at least 30 alleles, some of which may vary by as little as one base. At this locus a variation in the allele mobility was observed, depending on the electrophoretic conditions. For this reason, there should be careful consideration before this marker is accepted and validated as a common interlaboratory system. This paper does not include any comparison of the frequencies obtained for this locus with other recent studies. For the rest of the loci, the frequencies found have been compared with other published population studies; they show a degree of difference, particularly in the D1S80 locus. Finally, the systems were tested for Hardy-Weinberg equilibrium, and some statistical parameters of forensic interest were calculated.

Population genetics of three VNTR polymorphisms in two different Spanish populations.

Two different Spanish populations, one from Galicia (NW Spain) and the other from the rest of Spain, have been analyzed at three different hypervariable loci (YNH24, MS43a and MS31) using the EDNAP electrophoretic protocol and HinfI as restriction enzyme. Although the "rest of Spain" population is a clearly stratified population using classical blood groups, no evidence of stratification for these loci has been found and the differences to the Galician population were not significant, which suggests that a common Spanish population data-base could be possible. A semiparametric model is proposed for estimating frequencies, using the smoothed cross-validation of Hall et al. (1992) to calculate the size of the window utilized.

Inactivation and dissociation of S-adenosylmethionine synthetase by modification of sulfhydryl groups and its possible occurrence in cirrhosis.

Catalytically active human and rat liver S-adenosylmethionine synthetase exists mainly in tetramer and dimer form. In liver biopsy samples from cirrhotic patients a marked reduction in total S-adenosylmethionine synthetase activity and a specific loss of the tetrameric form of the enzyme exist. We have investigated the possible role of sulfhydryl groups in maintaining the structure and activity of S-adenosylmethionine synthetase. Both forms of S-adenosylmethionine synthetase are rapidly inactivated by N-ethylmaleimide, and the loss of enzyme activity correlates with the incorporation of approximately 2 moles N-ethylmaleimide per mole of subunit. In addition, reaction with N-ethylmaleimide resulted in displacement of the tetramer-dimer equilibrium of the enzyme toward the dimer, but no monomer was detected under these conditions. A catalytically active monomeric S-adenosylmethionine synthetase was detected in the cytosolic extract from a liver biopsy sample from a cirrhotic patient, supporting our model for the structure of S-adenosylmethionine synthetase. Because treatment of S-adenosylmethionine synthetase with N-ethylmaleimide resembles the situation of this enzyme in cirrhotic patients, it is proposed that impaired protection of the enzyme from oxidizing agents caused by a decreased synthesis of glutathione can explain the diminished synthesis of S-adenosylmethionine in liver cirrhosis.

Mechanisms and consequences of the impaired trans-sulphuration pathway in liver disease: Part I. Biochemical implications.

The energy-dependent conversion of methionine to S-adenosyl-L-methionine (SAMe) is catalysed by S-adenosyl-L-methionine synthetase (SAMe-synthetase) in the liver. In the hepatocyte, an equilibrium exists between the high and low molecular weight forms of SAMe-synthetase, which consist of a tetramer and a dimer, respectively, of a 48.5 kilodalton subunit. The 2 enzymic forms differ in their affinity for methionine and sensitivity to inhibition by pyrophosphate; 2 of the sulfhydryl groups of SAMe-synthetase have been identified as essential for the normal functioning of the enzyme. In patients with liver cirrhosis, a marked reduction in the utilisation of the high molecular weight SAMe-synthetase and displacement of the equilibrium occur, the molecular mechanism of which has yet to be established. This loss of activity is associated with a delay in methionine clearance and impairment of the trans-sulphuration pathway, which normally eliminates excess methionine by oxidising homocysteine to sulphate anion. It is hypothesised that in normal liver function the essential sulfhydryl groups of SAMe-synthetase are protected from oxidation by glutathione, a by-product of the trans-sulphuration pathway. However, glutathione levels are reduced in liver cirrhosis, and this may result in increased oxidation of the essential sulfhydryl groups, and consequent inactivation of the enzyme. Thus, the trans-sulphuration pathway may play an important role in the maintenance of normal SAMe-synthetase activity.

Specific loss of the high-molecular-weight form of S-adenosyl-L-methionine synthetase in human liver cirrhosis.

We have measured the activity of S-adenosyl-L-methionine synthetase, the ratio between the high- and low-molecular-weight forms of this enzyme and the concentration of S-adenosyl-L-methionine in liver biopsies from a group of controls (n = 6) and in six cirrhotics (five posthepatitic and one alcoholic). The total activity of S-adenosyl-L-methionine synthetase was markedly reduced in cirrhosis (37.5% of that found in the control group). This was due to a specific reduction in the high-molecular-weight S-adenosyl-L-methionine synthetase in the group of cirrhotics (73.9 pmoles per min per mg protein) when compared with that observed in controls (460.3 pmoles per min per mg protein). Despite this reduction in the rate of synthesis of S-adenosyl-L-methionine (the high-molecular-weight form of the enzyme is 15 times more active than the low-molecular-weight form at physiological concentration of substrates), the concentration of this metabolite was the same in the control group (17.3 +/- 2.6 microM) and in the group of cirrhotics (17.8 +/- 3.1 microM). To explain these findings, it is postulated that in human liver, where the concentration of S-adenosyl-L-methionine is lower than the Km values of a variety of enzymes that use this metabolite (around 50 to 100 microM), a reduction in the synthesis of S-adenosyl-L-methionine is compensated by a reduction in the rate of utilization of this molecule without affecting the intrahepatic concentration of S-adenosyl-L-methionine.(ABSTRACT TRUNCATED AT 250 WORDS)

Conversion of rat liver S-adenosyl-L-methionine synthetase from high-Mr form to low-Mr form by LiBr.

Rat liver S-adenosyl-L-methionine synthetase exists in two forms which are, respectively, a dimer and a tetramer of an Mr 48,500 subunit. The high-molecular-mass form is converted into the low-molecular-mass form by incubation with 1.4 M LiBr. The kinetic properties of the low-molecular-mass form obtained by LiBr treatment are the same as those obtained with the low-molecular-mass S-adenosyl-L-methionine synthetase form purified from rat liver cytosol. These results demonstrate that the differences in specific activity and regulatory properties of the high-molecular-mass and the low-molecular-mass S-adenosyl-L-methionine synthetase forms are due to their different polymeric states.

S-adenosyl-L-methionine synthetase and phospholipid methyltransferase are inhibited in human cirrhosis.

We have measured the activity S-adenosyl-L-methionine synthetase in liver biopsies from a group of controls (n = 17) and in 26 cirrhotics (12 alcoholic and 14 posthepatic). The activity of this enzyme was markedly reduced in the group of cirrhotics (285 +/- 32 pmoles per min per mg protein) when compared with that observed in controls (505 +/- 37 pmoles per min per mg protein). No differences in S-adenosyl-L-methionine synthetase was observed between both groups of cirrhotics. Similarly, a marked reduction in the activity phospholipid methyltransferase was also observed in liver biopsies from the same group of cirrhotics (105 +/- 12 pmoles per min per mg protein) when compared with the control subjects (241 +/- 13 pmoles per min per mg protein). Again, no difference in the activity of this enzyme was observed between both groups of cirrhotics. These results indicated a marked deficiency in the metabolism of S-adenosyl-L-methionine in cirrhosis.

Purification and comparison of two forms of S-adenosyl-L-methionine synthetase from rat liver.

Only two S-adenosyl-L-methionine synthetase forms exist in rat liver: high-Mr S-adenosyl-L-methionine synthetase and low-Mr S-adenosyl-L-methionine synthetase, which have been purified to apparent homogeneity as judged by sodium dodecyl sulfate/polyacrylamide gel electrophoresis. High-Mr S-adenosyl-L-methionine synthetase had an apparent molecular mass, determined by gel filtration, of 210 kDa and was a tetramer constituted by 48.5-kDa subunits, estimated by sodium dodecyl sulfate/polyacrylamide gel electrophoresis. The apparent molecular mass of low-Mr S-adenosyl-L-methionine synthetase, as estimated by gel filtration, was 110 kDa and was constituted by two subunits of 47 kDa. An antiserum against low-Mr S-adenosyl-L-methionine synthetase cross-reacted with the two forms. Reverse-phase HPLC runs of tryptic digestions of high-Mr and low-Mr S-adenosyl-L-methionine synthetase showed that the peptide maps of the two forms were very similar, if not identical. High-Mr S-adenosyl-L-methionine synthetase activity was inhibited by S-adenosyl-L-methionine and pyrophosphate. Depending on the dose used, S-adenosyl-L-methionine activated or inhibited low-Mr S-adenosyl-L-methionine synthetase and pyrophosphate had no effect on this form. The two synthetases showed a different specific activity at the physiological concentration of methionine. This report shows that even though the two forms are constructed of the same polypeptide chains, they are regulated in a different manner by methionine and by the products of the reaction.

Vasopressin-stimulated phosphorylation of rat liver phospholipid methyltransferase in isolated hepatocytes.

Addition of vasopressin (1 microM) to isolated rat hepatocytes prelabeled with [32P]phosphate was accompanied by a 250% increase in the phosphorylation of phospholipid methyltransferase. Vasopressin-stimulated phospholipid methyltransferase phosphorylation was time- and dose-dependent. 32P-labeled phospholipid methyltransferase was recovered by immunoprecipitation and SDS-polyacrylamide gel electrophoresis. After electrophoresis, phospholipid methyltransferase was electroeluted from the polyacrylamide gel and subjected to tryptic digestion or HCl hydrolysis. Analysis of 32P-labeled peptides reveals only one site of phosphorylation and the analysis of [32P]phosphoamino acids indicates that phosphoserine is the only labeled amino acid.