Non-linear dynamics of alpha and theta rhythm: correlation dimensions and Lyapunov exponents from healthy subject's spontaneous EEG.

The aim of the present paper was to analyze some non-linear dynamic properties of the resting EEG from healthy subjects under eyes closed conditions. For this purpose we digitally filtered the spontaneous EEG in the theta (3-8 Hz) and alpha frequency range (8-13 Hz) and considered these independent rhythms as signals from a deterministic system. Under certain conditions non-linear dynamic systems are able to generate deterministic chaos, which means that similar causes do not produce similar effects.

Measurement of albumin and low molecular weight proteins in the urine of newborn infants using a cotton wool ball collection method.

Objective: The aim of this study was to investigate the inter-relationship between urinary excretion of alpha-1-microglobulin (A1M), retinol-binding protein (RBP) and albumin in term and premature neonates, with urine collected into cotton wool balls and extracted by a novel method.

Subjects And Methods: Sixty-four infants were studied on the first day of life; 26 had been born at term (37-42 weeks gestation) and 38 prematurely (24-28 weeks n = 16, 29-36 weeks n = 22). Urine collected into cotton wool balls was analysed following a new detergent extraction method, which resulted in a recovery rate of 94-107% for albumin.

Spectral analysis of P300 generation in depression and schizophrenia.

In the past it was reported in several studies that both depressive and schizophrenic patients exhibit reduced P300 amplitudes compared to healthy controls. In order to elucidate the underlying mechanisms of spectral P300 generation, we analysed P300 responses in depression and schizophrenia by a frequency based approach. Herefore, the amplification (poststimulus/prestimulus) of spectral power in different frequency bands was evaluated for non-target and target epochs.

Neonatal and infantile upper gastrointestinal endoscopy using a new small diameter fibreoptic gastroscope.

Using a new prototype (Olympus XPGIF 5.2/ N30) gastroscope, upper gastrointestinal endoscopy was safely performed under sedation on 99 infants (weights 0.9 to 10.

Targeting of drugs and delivery systems to specific sites in the gastrointestinal tract.

Particle uptake and translocation occur at specific sites in the gastrointestinal tract. Several drugs are also absorbed from solution only through narrow "windows' in the small intestine. In these circumstances, optimum therapeutic benefit would be obtained if the active agent was targeted to the appropriate site in the gastrointestinal tract.

Single trial analysis of event related potentials: a comparison between schizophrenics and depressives.

The aim of the present paper was to perform a single trial analysis of event-related potentials in order to elucidate the mechanisms behind a reduced P300 amplitude occurring in unmedicated depressives (n = 11) and schizophrenics (n = 18). For this purpose, tools from linear system theory were applied to single trials in an oddball paradigm. This analysis provides estimates of the magnitude of the positive deflection occurring around the latency of P300 following target and nontarget simuli.

Progression of Organic Reactions on Resin Supports Monitored by Single Bead FTIR Microspectroscopy.

We report the time courses of five solid-phase reactions obtained using single bead FTIR microspectroscopy. This time-resolved information aided in the determination of the required reaction time, the nature of the solid-phase reaction, and resin property, effectively assisting in the initial phase of our combinatorial chemistry efforts. Our results showed that solid-phase organic reactions proceed faster than generally speculated.

MRI in children receiving total parenteral nutrition.

Cranial MRI was obtained in 13 of a group of 57 children receiving long-term parenteral nutrition, who were being investigated for hypermanganasaemia. Increased signal intensity on T1-weighted images has been reported in adult patients on long-term parenteral nutrition and with encephalopathy following chronic manganese exposure in are welding. It has been postulated that these changes are due to deposition of the paramagnetic trace element manganese.

A physiological profile of elite surf ironmen, full time lifeguards & patrolling surf life savers.

The physiological profiles and proficiency of 32 volunteer surf life savers (LS), 15 professional lifeguards (LG), and 8 elite surf ironmen (IM) aged from 18 to 44 were compared. Measurements included anthropometry, muscular power, muscular strength-endurance, flexibility, VO2max, maximum heart rate, peak blood lactate response and proficiency in 3 rescue simulations. Both LG and IM were significantly faster than LS in all rescue simulations.

Infantile chronic idiopathic intestinal pseudo-obstruction: the role of small intestinal manometry as a diagnostic tool and prognostic indicator.

Background: Chronic idiopathic intestinal pseudo-obstruction (CIIP) presenting in infancy is a rare but serious condition of heterogeneous aetiology often with an uncertain outcome.

Aim: To assess whether intestinal manometry in the first two years of life can help define a neuropathic or myopathic aetiology or clinical outcome, or both, in cases of infantile CIIP.

Subjects And Methods: 14 consecutive children who presented in the first year of life with CIIP were studied histologically and by small intestinal manometry.

Pectin/ethylcellulose film coating formulations for colonic drug delivery.

Purpose: The purpose of the study was to investigate the potential of pectin, ethylcellulose combinations as a practical film coating for colonic delivery.

Methods: Combinations of pectin and ethylcellulose, in the form of an aqueous dispersion, were used as coating formulations. Paracetamol cores were used as the substrate.

Surrogate data analysis of sleep electroencephalograms reveals evidence for nonlinearity.

We tested the hypothesis of whether sleep electroencephalographic (EEG) signals of different time windows (164 s, 82 s, 41 s and 20.5 s) are in accordance with linear stochastic models. For this purpose we analyzed the all-night sleep electroencephalogram of a healthy subject and corresponding Gaussian-rescaled phase randomized surrogates with a battery of five non-linear measures.

An approach to single trial analysis of event-related potentials based on signal detection theory.

The aim of the present paper was to introduce a single trial analysis to event-related potential measurement in order to illuminate the mechanisms behind an impaired P300 amplitude occurring under certain experimental conditions. For this purpose we applied tools from linear system theory and signal detection theory to single trials in an oddball paradigm in order to estimate the amplitude of the positive deflection around the P300 latency following target and nontarget stimuli. According to the density functions of these amplitude distributions we operationally defined 'P300 absent in target' (P300 amplitude smaller than an individual threshold under target conditions) as well as 'P300 present in nontarget' (amplitude greater than the threshold under nontarget conditions).

Manganese toxicity in children receiving long-term parenteral nutrition.

Background: In patients receiving long-term parenteral nutrition (PN), cholestatic disease and nervous system disorders have been associated with high blood concentrations of manganese. In such patients, the normal homoeostatic mechanisms of the liver and gut are bypassed and the requirement for this trace element is not known; nor has it been certain whether hypermanganesaemia causes the cholestasis or vice versa. We explored the direction of effect by serial tests of liver function after withdrawal of manganese supplements from children receiving long-term PN.

Discrimination of sleep stages: a comparison between spectral and nonlinear EEG measures.

During recent years, methods from nonlinear dynamics were introduced into the analysis of EEG signals. Although from a theoretical point of view nonlinear measures quantify properties being independent from conventional spectral measures, it is a crucial question whether in practice nonlinear EEG measures yield additional information, which is not redundant to the information gained by spectral analysis. Therefore, we compared the ability of several spectral and nonlinear measures to discriminate different sleep stages.

The distribution of dividing T cells throughout the intestinal wall in inflammatory bowel disease (IBD).

T cell hypersensitivity has been implicated in the tissue damage in Crohn's disease (CD). All studies to date have examined mucosal T cells, although much of the tissue damage occurs in the submucosa and muscle layers. The aim of this work was to study T cell proliferation throughout the intestinal wall in children with IBD.

[Sequential analysis of transmission properties of the CNS during consecutive REM periods].

Auditory and visual evoked potentials during sleep were recorded in healthy subjects. After averaging of the evoked potentials separately for the different REM episodes, the corresponding so-called amplitude-frequency-characteristic was calculated. This function describes the transfer properties of the system in the frequency domain.

Rapid detection and identification of pathogenic fungi by polymerase chain reaction amplification of large subunit ribosomal DNA.

We describe a polymerase chain reaction (PCR) based approach to the detection and identification of pathogenic fungi which has potential for the diagnosis of systemic mycoses. Primers to sequences of the large subunit ribosomal DNA genes, which are universally conserved within the fungal kingdom, were capable of amplifying DNA from 43 strains representing 20 species (12 genera) of medically important fungi. Sequence analysis of the products obtained from Aspergillus fumigatus, Candida albicans and Cryptococcus neoformans allowed us to design species-specific primers which only amplified homologous DNA.

Sequential analysis of the brain's transfer properties during consecutive REM episodes.

Classical analysis of the spontaneous sleep EEG has revealed alterations of REM sleep in psychiatric diseases and under the influence of drugs. In order to elucidate possible functional differences between different REM episodes even in healthy subjects we investigated in 10 volunteers the transfer properties of the brain by measuring auditory (AEP) and visual evoked potentials (VEP) from scalp positions Fz, Cz and Pz during the night. According to linear system theory we computed the so-called amplitude-frequency characteristics (AFC) from averaged AEPs and VEPs during the first and each of the following 3 REM episodes.

rDNA targeted oligonucleotide primers for the identification of pathogenic yeasts in a polymerase chain reaction.

Species-specific oligonucleotide primers were designed for PCR identification of the basidiomycetous yeasts Cryptococcus neoformans, Trichosporon cutaneum and Rhodotorula mucilaginosa. The procedure uses standard PCR components including DNA from the test species and three primers: two universal external (upstream and downstream) limiting primers and a species-specific internal primer. Species identification requires the formation of a species-specific rDNA nucleotide segment that is significantly smaller (approximately 200 bp) than a non-target segment (approximately 600 bp).

Nonlinear analysis of sleep EEG data in schizophrenia: calculation of the principal Lyapunov exponent.

The generating mechanism of the electroencephalogram (EEG) points to the hypothesis that EEG signals derive from a nonlinear dynamic system. Hence, the unpredictability of the EEG might be considered as a phenomenon exhibiting its chaotic character. The essential property of chaotic dynamics is the so-called sensitive dependence on initial conditions.

Nonlinear analysis of sleep EEG in depression: calculation of the largest lyapunov exponent.

Conventional sleep analysis according to Rechtschaffen and Kales (1968) has provided meaningful contributions to the understanding of disturbed sleep architecture in depression. However, there is no characteristic alteration of the sleep cycle, which could serve as a highly specific feature for depressive illness. Therefore, we started to investigate nonlinear properties of sleep electroencephalographic (EEG) data in order to elucidate functional alterations other than those obtained from classical sleep analysis.

Nonlinear dynamical aspects of the human sleep EEG.

This article deals with the application of methods from the theory of nonlinear dynamical systems to EEG signals. Theoretical background, mathematical concepts and algorithms for the calculation of "non-linear parameters" are reviewed and influences of the structure of reconstructed data sets on the calculations are pointed out. We present results for the estimation of the correlation dimension D2 and the principal Lyapunov-exponent lambda 1 for sleep EEG data respectively from 10 and 15 healthy subjects corresponding to different sleep stages.

Nonlinear EEG dynamics during sleep in depression and schizophrenia.

The article deals with the question, whether nonlinear analysis of the sleep EEG may give clues to understanding of disturbed information processing in psychiatric diseases. We point out how the nonlinear approach to EEG dynamics is motivated and review recent investigations concerning nonlinear dynamical properties of physiological systems. We present calculations of the correlation dimension D2 and the principal Lyapunov-exponent lambda 1 for sleep EEG data from 9 depressive and 11 schizophrenic inpatients compared to healthy controls.

Targeting drugs to the colon: delivery systems for oral administration.

The oral delivery of drugs to the colon has applications in a variety of therapeutic areas. This review is concerned with the approaches taken to achieve a universal system for delivery. The design of such a system requires the identification and exploitation of a unique feature of the colonic environment.