W. Berg

Correlations between the autonomic modulation of heart rate, blood pressure and the pupillary light reflex in healthy subjects

Information on autonomic modulation can be derived from different organs that are innervated by the sympathetic and the parasympathetic nervous system, when assessing e.g. heart rate or blood pressure fluctuations or the pupils reaction to light. Correlations between parameters from different target organs might reveal information on hierarchically higher centres of autonomic integration. Here, we obtained parameters of heart rate variability, blood pressure variability, baroreflex function and light reaction pupillography from 50 individuals and tested the hypothesis that these are associated. Pupil diameter and constriction latency significantly correlated with parameters of heart rate variability, but not with those of blood pressure variability. In contrast, relative amplitude significantly correlated with blood pressure variability only. In conclusion, the different branches of the autonomic nervous system examined here are not associated unequivocally but show a distinct pattern of interrelations in healthy subjects. Examinations as described here might add to the diagnosis of autonomic dysfunction and reveal differential patterns in certain disease states.

Scanning electron microscopic investigations on the morphology and phase conversions of uroliths

The most frequent structures of the majority of possible urolith components are assessed by scanning electron microscopic investigations. Typical examples for the conversion of uric acid dihydrate into uric acid, weddellite into whewellite and MgHN4PO4·6H2O into MgNH4PO4·H2O are given.

A contribution to the formation mechanism of calcium oxalate urinary calculi

Summary25 to 30% of calcium oxalate urinary calculi consist of the metastable Weddellite crystal phase. By fractionation of urine it was found that mineral substances are stabilising factors. The stability was checked in dry condition at room temperature, at 38°C and at 110°C. These results could be confirmed by precipitation from synthetic solutions. Mg, Zn, Ni, Co, Mn and Cu individually, and above all in combination, promote the formation of Weddellite. The formation of mixed crystal phases must be considered one of the main factors for the stabilisation of Weddelite in the urinary calculus.

A Gel Model for Measuring Crystallization Inhibitor Activities

We devised a simple and economical technique for measuring crystallization inhibitory activities. Calcium ions and oxalate ions diffuse towards one another from two adjacent wells in a layer of gel on a microscope slide. Where they meet, a streak of calcium oxalate crystals forms. Substances which influence crystallization are caused to diffuse into this middle zone. Depending on the inhibitory potency of the substance, the calcium oxalate streak varies in density and extent. These differences are recorded photometrically by comparison with a sample containing no inhibitor, and the inhibition index is calculated. Some of the best known inhibitors were tested and showed a definite effect in this model. Magnesium and citrate in physiological concentrations are of special significance. The expected range of variation of inhibitory activities in human urine is covered by this method.

Stress und Harnsteinbildungsrisiko

In the present work the influence of stress situations on the concentrations and excretions of lithogenous urinary substances (calcium, oxalic acid, uric acid) has been studied in defined urine portions of 10 calcium oxalate stone patients and 10 normal subjects and the results compared to those of 20 stone patients and 10 normal subjects without stress. Stress may be objectified in the given task. The increase of concentrations and excretions of lithogenous urinary substances indicates an enhanced risk of stone formation. Uric acid is discussed as an agent promoting the calcium oxalate crystallization. New insights on the calcium oxalate stone genesis are gained from the results.

Assessment and maintenance of the quality of urolith analyses in a comparison of methods. 4th International Ring Test to check quality.

AbstractFor five test samples of the fourth International Ring Test to check the quality of methods for urinary calculus analysis, 45 findings obtained by 10 different methods were sent from 16 countries. The mean deviation of 0.11 molecular parts per component for all five samples is considerably low. The average standard

Comparison of Methods and Guaranteeing Quality of Analyses of Urinary Calculi – 5th International Ring Test

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Crystal-Optical Findings on Calcium Oxalate of Uric Concretions

for all participants is 2.44. It falls off from X-ray diffraction via IR down to other quantitativemethods. Advantages and disadvantages of X-ray diffraction and IR-spectroscopic analyses are discussed. Analysis of urinary calculi according to centralized, methodically uniform standards offers advantages in analytical quality.