Application of R-charts to detection of random errors: a computer simulation study.

The application of R-charts to quality control in clinical chemistry was investigated. These charts are widely used in statistical process control and plot the range (ie the difference between the highest and the lowest values) of a set of controls. A set of five control serums was considered. A computer simulation program was developed for this investigation. It showed a power function that is remarkably insensitive to systematic errors. Consequently these charts may be a useful tool in discriminating between systematic and random errors, helping the trouble-shooting significantly, if used concurrently with Levey-Jennings' charts. Nevertheless, as several control samples are necessary, this technique is not cost-effective for short analytical runs.

ERP study of the development of the holistic and analytic modes of processing between 6 and 8 years.

Event-related potentials (ERPs) were recorded (01, 02, Fcz, Cpz leads) from 32 normal children aged from 6 to 8 years during a categorisation task performed with 4 types of stimuli that allowed for a holistic and/or an analytic development to modify information processing according to the child's age. Whatever age, derivation or stimulus, the individual ERPs showed a large negative N2 wave (mean latency: 230 ms) made up of two widely overlapping components. In order to separate these components, an initial principal component analysis (PCA) was performed on the waveforms; this PCA provided a principal component that accounted for the amplitude difference between the first negative peak of the N2 wave (180 ms after stimulus onset) and the subsequent slope change. A second PCA was then carried out on the corresponding individual component scores; this second PCA provided two factors according to whether the stimuli were holistically or analytically processed. Regarding the pre- and post-vertex data (Fcz and Cpz), these two factors accounted for the same ERP effect for the 6-year-old children but opposite effects after the age of seven. We interpreted this change as reflecting the differentiation of specific - holistic and analytic - modes of processing from a non-specific mode after the establishment of the concrete operation period.

Alterations of the functional properties of the parallel fibers in the cerebellum of the "scrapie mouse".

Alterations of the functional properties of the cerebellar parallel fibers have been investigated in scrapie mice by recording the compound action potential elicited by the superficial stimulation of the cerebellum. As soon as the 12th week following intracerebral inoculation, i.e. during the silent incubation period, there is a clear decrease of the response amplitude and of the recruiting properties. Depth profiles of the response indicate the progressive disappearance of the most superficial fibers. With respect to the remaining parallel fibers, the conduction velocity becomes progressively reduced, the duration of the refractory periods increases and the hyperexcitability and increased velocity characterizing the supernormal period are greatly reduced. Most of these electrophysiological alterations can be related to changes of the membrane properties and/or modifications of the metabolic processes ensuring the active ionic transport across the membrane.

[Pigmentary retinopathy of neonates and infants. Their examination using electroretinography and visual evoked potentials]. / Rétinopathies pigmentaires du nourrisson et de l'enfant. Leur exploration par l'électrorétinogramme et les potentiels évoqués visuels.

A method of neurophysiological investigation (electroretinography and visual evoked potentials) is described as a non invasive exploration used in awake children. E.R.G. and V.E.P. normal patterns are described in relation to age. The data obtained in pigmentary retinopathies are referred to the physiopathology of these diseases. Usefulness of both neurophysiological tests is showed in the early diagnosis. Significative abnormalities are seen even before any detectable ophthalmoscopic symptom. In pigmentary retinopathies, V.E.P. are normal while E.R.G. is slightly then severely altered. E.R.G. and V.E.P. are also helpful in the differential diagnosis: in macular diseases, E.R.G. is usually normal while V.E.P. are altered. Repeated examinations have a prognostical value: when a disease is progressing, E.R.G. becomes more and more altered and V.E.P.'s abnormalities appear.

[Maturation of late visual potentials linked to cognitive processes in the normal child]. / Maturation des potentiels visuels tardifs liés aux processus cognitifs chez l'enfant normal.

In 21 normal children in age ranging from 6 to 9 years, endogenous P300 components were recorded on vertex and occipital areas. The ERPs were provoked by error detections in various tasks of visual discrimination involving cognitive abilities of the subjects. The data reveal an obvious influence of the age according to the number of the detected P300 and the correlations between presence and/or absence of the vertex and occipital responses. The limit of 7 years of age seemed important for the maturation of the P300 system.

Fluorocarbons: a potential treatment of cerebral air embolism in open-heart surgery.

This study was designed to assess whether an oxygenated fluorocarbon solution could reduce ischemic brain damage related to arterial air embolism. Air embolism was produced by injecting air bubbles into the carotid artery of barbiturate-anesthetized rats breathing 100% oxygen. Results were assessed on electrocorticogram. In an additional set of experiments, mass spectrometry was used to provide continuous monitoring of intracerebral tissue oxygen (PO2) and carbon dioxide (PCO2) tensions and intermittent measurement of cerebral blood flow (CBF). Fluorocarbon or saline solution (containing the emulsifying agent of fluorocarbons) was given intravenously after the initial air embolism (0.2 ml), and injections of air (0.1 ml) were repeated thereafter every five minutes. The maximal amount of air required to achieve complete and irreversible flattening of the electrocorticogram was 1.60 +/- 0.06 ml (mean +/- standard error of the mean) in the saline-treated rats and 5.20 +/- 0.44 ml in the fluorocarbon-treated group (p less than 10(-7)). In the second experiment, air embolism caused CBF to rise in both groups, the average percent of increase being higher in treated (41.6%) than in control animals (38.3%) (p less than 0.02). However, in the control group, the increase in CBF did not prevent intracerebral tissue PO2 from decreasing by 7.4 +/- 7.0% over the same period; conversely, in the fluorocarbon group, PO2 levels fell by only 2.5 +/- 3.7% (p less than 0.001 versus controls), but this time-averaged percentage was calculated over a longer period of cumulative ischemia because of the greater number of air emboli tolerated by treated animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Drug-induced activation of the inferior olivary nucleus in young rabbits. Differential effects of harmaline and quipazine.

Ontogenic evolution of behavioural and electrophysiological responses to the serotonergic agents, quipazine and harmaline, was studied in the maturing rabbit in normal and pretreated conditions. As regards behavioural effects, tremor induced by quipazine was present from the first postnatal day and was antagonized by methysergide, but not by p-chlorophenylalanine (PCPA) or pretreatment with 5,7-dihydroxytryptamine (5,7-DHT). In contrast, tremor induced by harmaline could not be elicited before the second postnatal week and was partially antagonized by methysergide and 5,7-DHT, but not by PCPA. Electrophysiological studies of cell activity in the inferior olivary nucleus revealed a similar dependency on age since rhythmic activation of the inferior olivary nucleus could be registered from the first postnatal day with quipazine and only from the 8th postnatal day with harmaline; drug interactions with methysergide, PCPA and 5,7-DHT were the same as for the behavioural observations. It is suggested that quipazine directly activates serotonin receptors which are already present at birth, whereas harmaline requires the presence of serotonergic fibres for such activation.

Locked in syndrome with a favourable outcome.

The locked in syndrome seldom occurs in children, is rarely due to trauma and only in exceptional cases has a favourable outcome. The case reported below is unusual in all these respects, and its evolution might be an example of successful axonal regeneration in the central nervous system.

[Place of VEP's and ERG in neonatal encephalopathies and impaired visual maturation in the infant and young child]. / La place des PEV et des ERG dans les encéphalopathies néonatales et les troubles de la maturation visuelle du nourrisson et du jeune enfant.

Visual evoked potentials (VEPs) induced by brief flashes and electroretinograms (ERGs) were recorded in 15 infants (9 prematures and 6 babies with perinatal cerebral injuries) suffering from important disturbances in their visual behavior (abnormal fixation, cortical blindness). The parallel evolution of the visual symptoms and the electrophysiological signs were studied and a good correlation was observed between these clinical and electrical signs. The authors insist on the clinical and prognostic value of the VEP in this category of infants.

Purification and properties of carboxylesterase B of Escherichia coli.

Carboxylesterase B produced by Escherichia coli was purified 1,350-fold with a recovery of 12% by successive gel filtrations, DEAE-trisacryl, phenyl-Sepharose chromatography and preparative electrophoresis. The purified enzyme was found to be homogeneous, as judged by a single precipitation line in Ouchterlony double diffusion in an experiment with homologous antiserum. The apparent molecular weight determined by gel filtration and the isoelectric point determined by electrofocusing were 57,000 and 4.6, respectively. Using acetate, propionate and butyrate esters of 1-naphtol, it was observed that elongation of the acyl carbon chain resulted in a progressive increase in velocity of ester hydrolysis. The apparent Km for 1-naphtyl acetate was found to be 0.25 mM. The enzyme was maximally active at pH 7.4 and was found to be unstable below pH 5. Hydrolytic activity was preserved after heat treatment for 30 min at 60 degrees C, but was abolished by heating for 10 min at 70 degrees C. The enzyme was strongly inhibited by low concentrations of di-isopropyl fluorophosphate. This suggested that a serine residue is required for catalytic activity. Esterase was unaffected by tosyl-L-lysin chloromethylketone, iodoacetamide, 4-hydroxy-mercuribenzoate and EDTA. Using antiserum against purified carboxylesterase B of E. coli, significant immunological cross-reactions were observed between this antigen and carboxylesterase B produced by Shigella flexneri, S. boydii and S. sonnei.

[Electromyographic study of 50 cases of Werdnig-Hoffmann disease]. / Etude électromyographique de 50 cas de maladie de Werdnig-Hoffmann.

An electromyographic study was performed in 50 cases of severe infantile spinal muscular atrophy (type I). 164 muscles and 93 nerves (ulnar and posterior tibialis) were tested. The thresholds of stimulation of the motor nerves were increased. Motor action potential was absent in 30% of the investigated nerves, motor nerve conduction velocity was slow in 44%, H reflex was absent in 86%. Proprioceptive nerve conduction velocity was slow in some cases. Using the long-time (50-100 msec) direct longitudinal technique of muscle stimulation (provoked fibrillation), denervation could be proved in 98% of cases. The authors emphasize diagnostical difficulties in the first days of life.

[Technic and results of electromyographic exploration of the diaphragm in the infant and young child]. / Technique et résultats de l'exploration électromyographique du diaphragme chez le nourrisson et le jeune enfant.

Electromyographic study of the diaphragma cannot be separated from the exploration of the nervi phrenici. The left nervus phrenicus is longer than the right. Both divide into 3 terminal branches that innervate the 3 main muscular areas. A different recording technique is used for each muscular area: thoracic surface electrodes for the cupulae, oesophageal probe electrodes for the crura diaphragmatis, and needle electrodes for the pars sternalis. Voluntary activity, recorded only during inspiration, is of limited use in pediatrics. The various parameters of the response to stimulation of the nervi phrenici, which are described here, are more interesting. In particular the latency period for each muscular area as a function of age is examined in detail to give an impression of the nerve conductivity.

[Use of SDS and saponin detergents for the demonstration and purification of (Na+K+)ATPase in sheep kidney]. / A propos de l'utilisation des détergents SDS et saponine pour le démasquage et la purification de la (Na+K+)ATPase de rein de mouton.

Incubation of membrane fragments from sheep kidney outer medulla in detergents such as SDS or saponin revealed increased specific (NA+) ATPase activity. Measurement of enzyme phosphorylation from [gamma 32P] ATP showed irreversible alteration of EP to (Na+) ATPase activity ratio when SDS is used as unmasking agent. These results were found with unmasked and purified enzyme.

Nervous and ocular disorders in children with cholestasis and vitamin A and E deficiencies.

Thirteen children, aged 10 months to 20 years, presenting with chronic cholestasis from the first month of life and with low serum levels of vitamins A and/or E, have been investigated for neurological and ophthalmological symptoms. Clinical findings consisted of 4 types: peripheral neuropathy; cerebellar dysfunction; abnormalities of eye movement, and retinal degenerative changes. The results of electrophysiological and morphological studies of muscle and nerves were consistent with neurono-axonal degeneration. Electrical abnormalities of the retina, especially a decrease of the b wave of electroretinogram, appear to be the first sign of the syndrome, allowing early detection. Evidence for vitamin deficiency (E or E+A) suggests substitutive parenteral treatment in such patients.

Detergent effects of kinetic properties of (Na+ +K+)-ATPase from kidney membranes.

Studies on (Na+ +K+)-ATPase generally employ detergents such as SDS and deoxycholate. Under such conditions, the purified enzyme possesses high specific activity. The (Na+ +K+)-ATPase from kidney membranes was unmasked by deoxycholate and SDS as described by Jlrgensen and its kinetic properties were studied. The results suggest that these detergents induce some irreversible alterations in the kinetic properties of the native enzyme. Another detergent, saponin, unmasked the (Na+ +K+)-ATPase as effectively as did SDS, but it seems to affect the kinetic properties of the native enzyme to a lesser extent.