Ferrate(VI) oxidation of cyanide in water.

Experiments were conducted to test removal of cyanide (free cyanide and several cyanide complexes) in water, under alkaline medium (pH > or = 11), by a new potassium ferrate salt. The removal rate of free cyanide by oxidation with Fe(VI) was greater at pH 11.0 than at pH 12.0. A complete oxidation was obtained with a 2.67 Fe(VI)/CN ratio at pH 11.0. In these conditions, the rate of cyanide oxidation by Fe(VI) was slow, with a reaction rate constant estimated at 0.95 +/- 0.10 s(-1) l mol(-1) at pH 11.0 and 19.6 degrees C in this study. This study revealed that Fe(VI) did not decompose all cyanide complexes. Copper, cadmium and zinc complexes were removed efficiently by Fe(VI). Moreover, these metals were also removed from the solution by coagulation effect of Fe(OH)3, the Fe(VI) product of reaction. A particular behaviour was reported with copper, as a rapid oxidation of cyanide was observed in the presence of this metal. On the contrary, oxidation of nickel and silver complexes was incomplete.

State-of-the-art potential clamp device for myelinated nerve fibres using a new versatile input probe.

A potential clamp device for myelinated axons is presented which, for the first time, systematically optimizes all the methodological parameters that limit the reliability of ionic current measurements. A crucial step toward this end consisted in the development of a new input probe with broad-band, extremely low-capacitance characteristics. In combination with a simple-to-use compensation criterion for optimum positive feedback, based on plausible assumptions, and with additional technological improvements, it enables the measurement of ionic currents with a reliability never previously achieved. The consequences with respect to evaluation of several earlier findings are discussed.

Mode of action of psoralens, benzofurans, acridinons, and coumarins on the ionic currents in intact myelinated nerve fibres and its significance in demyelinating diseases.

The actions of psoralens, benzofurans, acridinons and coumarins on the ionic currents in intact myelinated nerve fibres were investigated. All 6 substances blocked the potassium currents in a time-dependent manner, producing so-called K+ transients. Only 5-methoxypsoralen is a largely selective blocker of predominantly the axolemmal potassium channels, which is the characteristic required by our previously proposed working hypothesis for the mechanism of potassium-channel blockers in demyelinating diseases, in particular multiple sclerosis. If the observed K+ transients were to arise by blocking of the potassium channels of the Schwann cell, that is, by the periaxonal accumulation of K+ and a resulting collapse of the electromotive driving force for potassium-ions, according to a modified version of our previous hypothesis the other substances tested could also have a beneficial effect on the impaired impulse conduction in demyelinated axons. In this case a large number of new potential drugs would be available for the symptomatic therapy of MS.

Development and outcome of indices of obesity in normal children.

Based on the Zürich longitudinal growth study, differences are analyzed between those children who later became light adults (later light) and those who later became heavy (later heavy) adults. This is of interest to discover how and when overweight develops, and which variables are most affected (weight, body mass index, circumferences and skinfolds are studied). A further question is whether maturation proceeds differently in these children. The principal idea is to split the sample with respect to adult body mass index into three parts, and to analyse the two extreme groups. It is shown that structural average curves for these subgroups lead to a substantial insight into the processes going on in different variables. Whereas maturation is not much different, subjects later heavy gain substantially more in fat and body mass index from about 4 to 5 years onwards. The natural pattern of ups and downs becomes exaggerated in subjects who are to become heavy at adult age. In those phases where it is natural to build up body mass index there is not much of a difference. In phases where later lean subjects hardly increase their body mass index, later heavy subjects continue to build it up substantially.

The dynamics of growth of weight, circumferences and skinfolds in distance, velocity and acceleration.

Based on structural average curves of distance, velocity and acceleration, an analysis of the longitudinally assessed growth of weight, arm and calf circumferences and skinfolds (biceps, triceps, suprailiac, subscapular) was undertaken. The data come from the first Zürich longitudinal growth study and represent a normal sample. In addition to a graphic analysis, timing, intensity and duration of the mid-growth spurt (MS) and of the pubertal spurt (PS) are quantified via descriptive parameters of growth. Mechanisms are different and more complex for these variables, in particular for skinfolds, compared to previously studied somatic variables, such as height. Skinfolds showed a rapid decline to a negative velocity minimum in the first year, recovering to a pre-PS fat spurt, earlier and more pronounced for central (suprailiac, subscapular) than for peripheral skinfolds (biceps, triceps). At age of peak height velocity a drop occurred, stronger for boys, followed by a post-PS spurt. A further analysis demonstrates that these ups and downs in skinfold velocity are mainly due to subjects with thick skinfolds. Weight and circumferences show a distinct MS, with sex-independent characteristics and a strong, sex-dependent PS. Weight and even more arm circumference are delayed compared to height in puberty.

The dynamics of growth of width in distance, velocity and acceleration.

In this paper the dynamics and intensity of the growth of bihumeral and biiliac width and of humerus and femur bicondylar diameter are studied and compared, and sex differences are established. The analysis is based on a newly introduced statistical tool, the structural average curve for distance, velocity and acceleration. It accounts for individual developmental tempo and allows pooling data for a sample of subjects. In all four variables studied, a sharp decline in velocity after birth is followed by a more gradual decline in infancy and childhood. A mid-growth spurt (MS) at about age 7 can be found in all variables, of about equal timing and intensity for the two sexes. The pubertal spurt (PS) is earlier for girls, and less intense except for biiliac width. The study shows a characteristic pattern across variables of width regarding the intensity of growth in different periods. The accentuated MS and PS for bihumeral width, contrasting with relatively early and small PS for the bicondylar width of femur, are remarkable.

Effects of some potassium channel blockers on the ionic currents in myelinated nerve.

The effects of some potassium channel blockers on the ionic currents and on the so-called K(+)-depolarization in intact myelinated nerve fibres were studied. 4-AP, and in particular, Flaxedil, proved to be selective K(+)-current blockers. However, TEA, a crown ether (DCH18C6), a longchained triethylammonium compound (C10-TriEA), capsaicin, and the extract from the medicinal herb Ruta graveolens proved not to be selective K(+)-current blockers; they all block Na(+)-currents as well, although to a lesser extent. The sodium inactivation curve did not change under TEA and Flaxedil but was shifted on the potential axis in negative direction by DCH18C6, 4-AP, capsaicin and the Ruta extract whereas C10-TriEA caused a shift of both sodium inactivation and activation parameters in positive direction. Regarding to the kinetics of the persisting K(+)-current fraction, two different kinds of blockade were found: 1. Unchanged K(+)-kinetic which is typical for the effects of TEA, 4-AP, Flaxedil, and C10-TriEA. 2. Clearly changed K(+)-kinetic, characterized by K(+)-transients; which is typical for the effects of capsaicin and in particular, for those of DCH18C6 and of the Ruta extract. The possibly different modes of action of both groups of blockers are discussed in terms of current models for the action of potassium channel blockers.

The dynamics of linear growth in distance, velocity and acceleration.

Growth of body, leg, trunk and arm length from birth to adulthood is studied in the subjects of the First Zürich Longitudinal Growth Study, using a recently developed technique, the 'structural average curve'. In this way truly longitudinal average curves are obtained for velocity, acceleration and distances, and various phases of growth are analysed not only graphically, but also by descriptive parameters in terms of timing, intensity and duration. These phases consist of the pubertal spurt (PS), the mid-growth spurt (MS) and growth in infancy. The overall pattern is the same in all variables studied: velocity drops sharply after birth, followed by a kink between 7 and 12 months, and a more gradual decrease until the MS, which peaks around 7 years. In girls the PS immediately follows the MS, while in boys a 'latency period' of approximately constant growth velocity precedes the PS, which occurs almost 2 years later, and is more intense than in girls. There are no appreciable sex differences in the MS, but the PS is later and more intense for boys, even when accounting for the smaller adult size of girls. When comparing linear variables the PS turns out to be earlier for the legs than for the trunk, whereas the trunk has an earlier MS. The trunk starts high in relative distance and in velocity after birth, whereas the legs have a high velocity throughout childhood. In adolescence the trunk again shows more intense growth. Surprisingly, the growth of the arms in many ways resembles more that of the trunk and not that of the legs.

A method for determining the dynamics and intensity of average growth.

A new statistical method is presented for determining an average growth curve which is valid in the sense of representing both the average dynamic, or tempo, and the average intensity of the growth process studied. In this context, growth curve means either distance, velocity or acceleration curve. The principal idea is to shift individual curves continuously (and non-linearly) in age to an average developmental age scale. Since the resulting curves represent the typical shape rather than individual variations of it, they are of interest for comparisons of different variables of boys and girls and of subgroups. The method is illustrated with longitudinal growth data from the first Zurich longitudinal study.

Velocity and acceleration of height growth using kernel estimation.

A method is introduced for estimating acceleration, velocity and distance of longitudinal growth curves and it is illustrated by analysing human height growth. This approach, called kernel estimation, belongs to the class of smoothing methods and does not assume an a priori fixed functional model, and not even that one and the same model is applicable for all children. The examples presented show that acceleration curves might allow a better quantification of the mid-growth spurt (MS) and a more differentiated analysis of the pubertal spurt (PS). Accelerations are prone to follow random variations present in the data, and parameters defined in terms of acceleration are, therefore, validated by a comparison with parameters defined in terms of velocity. Our non-parametric-curve-fitting approach is also compared with parametric fitting via a model suggested by Preece and Baines (1978).