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The method parameters of an almost one century old method for analyzing nickel as dimethylglyoximate were critically examined for the analysis of nickel raw materials and many of the method parameters were observed to have a significant effect on the Ni recovery. Thus, because the Ni precipitation method parameters vary a lot in analytical literature and also in practice, the obtained Ni results by different methods are not comparable. During this study it was found that the double precipitation worked out perfectly in eliminating the effects of impurity elements. The residual Ni content in the filtrates should also be measured to obtain accurate and precise Ni results. In complexing the impurity elements, tartaric acid, stabilized by acetic acid, turned out to be effective, and when added to the sample solution before ammonium addition, the best pH conditions for homogenous Ni precipitation with dimethylglyoxime were obtained. The optimized Ni determination method described was found to be accurate and highly reproducible when tested with Ni concentrates and standard reference materials containing high Ni concentrations. [ABSTRACT FROM AUTHOR]

A simple and rapid method for the determination of SiO2 in lime mud used in current sulfate pulping practice is reported. The lime mud samples are treated three times with 2.5 mL of 6 mol/L hydrochloric acid. The samples are nearly evaporated to dryness two times and the third time to complete dryness. To determine the exact SiO2 content of the residue, it is treated with an excess of concentrated hydrofluoric acid and a little hydrochloric acid, and the silica is expelled as volatile silicon tetrafluoride. The sample treatments take about 1.5 h and the heating periods take a total of about 3.5 h. The SiO2 results were evaluated by analyzing National Institute of Standards and Technology Standard Reference Materials, SRM, (1c, 694 and 88b). The method was found to be accurate and precise in a 95% confidence interval, rapid, and highly repeatable. The repeatability standard deviation for SRMs was calculated to be 0.49%. [ABSTRACT FROM AUTHOR]

We studied the levels of excitatory and inhibitory amino acids in the cerebrospinal fluid (CSF) of 28 epileptic patients (24 with partial type seizures, 4 with primary generalized seizures) and 12 controls. The levels of aspartate were 63% (p<0.01), glutamine 129% (p<0.001), and homocarnosine 127% (p< 0.005) that of controls. The concentrations of glutamate, asparagine, total GABA, free GABA, taurine, and glycine did not differ between epileptic patients and controls. Patients with partial epilepsy had a pattern of amino acids in CSF similar to that in patients with primary generalized seizures. In the present study we did not observe increased excitation or decreased inhibition in the seizure-active brains of epileptics, as far as the CSF levels of amino acids reflect their levels in the brain. [ABSTRACT FROM AUTHOR]

1. The anticonvulsant potency of vigabatrin (gamma-vinyl GABA, GVG) was studied in an open trial in a group of 21 mentally handicapped patients with drug-resistant epilepsy. 2. With this treatment one third of these patients had more than 50% reduction in seizure frequency. The anticonvulsant effect appeared during the first month of therapy and was maintained during a 7-month study. The side effects were mild: mainly tiredness, aggressiveness, and ataxia. Other anticonvulsant drugs remained at baseline levels during GVG therapy. GVG was not found to modulate EEG recordings. 3. According to our results, GVG is effective for treating intractable epilepsy in mentally handicapped patients. [ABSTRACT FROM AUTHOR]

As part of a prospective follow-up study of two premature cohorts (gestational age less than or equal to 36 weeks) born between 1976 and 1977, designed to evaluate the effects of IUGR on morbidity, mortality and neurological development in prematurely born children, 71 prematurely born children (48 AGA, 23 IUGR) without major neurological handicaps were subjected to detailed assessment of their neurological and psychological status at the age of 4 years. Thirty-six healthy full-term children formed a control group. The socioeconomic status of the families of the premature groups was similar to that of the families of the control group. The assessment consisted of a neurodevelopmental screening test and four psychological tests. Validation of the NDS test in relation to proven cognitive problems (sensitivity 96%, specificity 64%, relative risk 16.74) and determination of normal ranges were based on findings in the control group. There were significantly more children with moderate to high risk scores (greater than or equal to 10) among the IUGR group than among the AGA group. The neurodevelopmental profile of the preterm IUGR group was characterized by complex deviations of motor, visual and perceptual functions from normal. Preterm AGA children had only slightly higher risk scores in relation to fine motor, upper motor and perceptive functions than control children. Of the various perinatal factors studied, IUGR (especially in relation to boys who needed respirator therapy) was the most likely to be associated with abnormal NDS scores before school age. [ABSTRACT FROM AUTHOR]

Vigabatrin (gamma-vinyl GABA) is a new anticonvulsive drug that irreversibly inhibits the activity of GABA transaminase. The effect of vigabatrin on neurotransmission-related amino acids in CSF of 28 epileptic patients was studied and the relationship between the amino acid pattern and clinical response during 7 months of administration of vigabatrin. Of this study population, 46% had more than 50% decrease in seizure frequency (responders). In 54% the seizures decreased less than 50% (nonresponders). In the whole study group, the levels of total GABA during vigabatrin treatment were 283%, free GABA 197%, homocarnosine 310% and glycine 128% that of the levels at baseline in the same patients. Glutamate, glutamine, aspartate, asparagine, and taurine concentrations did not change. The amino acid pattern in CSF during administration of vigabatrin did not differ significantly in responders and nonresponders. The study suggests that both GABAergic and glycinergic neurotransmission are affected by vigabatrin. The changes in CSF levels of neurotransmitter amino acids are, however, not necessarily related to the clinical response. [ABSTRACT FROM AUTHOR]

The frequencies of folate-sensitive autosomal rare fragile sites (ARFS) were compared in populations of mentally retarded, mentally subnormal, and mentally normal children and of patients referred for diagnostic chromosome study. The frequencies did not differ significantly. Altogether, an autosomal rare fragile site was found in 16 of 1445 individuals (1 in 90). Of six different folate-sensitive ARFS detected, the most common one was FRA9A, with a frequency of 1 in 241 individuals. In addition, FRA17A, classified as a distamycin A-inducible fragile site, was found with a frequency of 1 in 206. It was regarded as a spontaneously expressive fragile site. In 19 families in which transmission of an autosomal rare fragile site was studied, the mother was the carrier in 16 families and the father, in one family. The mean percentage (±SD) of cells expressing ARFS in 55 individuals was 19% (±11.4). The age did not affect the rate of expression. When the rate of expression was calculated separately in a group of mentally retarded (mean=23.4%) and in a group of mentally normal individuals (mean=16.0%), the difference was statistically significant. [ABSTRACT FROM AUTHOR]

The prevalence of the fragile X syndrome among 12,882 children (6594 boys and 6288 girls) born during the years 1969-1972 in Kuopio province in eastern central Finland has been studied retrospectively. Mentally retarded children were selected from normal schools by using school achievement tests and from registers of mentally retarded individuals. In the present study fragile X syndrome was found in 6/111 mentally retarded children (5.4%), in 4/61 boys and in 2/50 girls, respectively. It was not detected in the control group of 85 healthy children. The corrected prevalence of fragile X syndrome among boys in four successive birth cohorts was estimated to the 1 in 1210 or 0.8/1000, and that among girls, 1 in 2418 or 0.4/1000. The overall prevalence was calculated to be 1 in 1612 or 0.6/1000 children. [ABSTRACT FROM AUTHOR]