Characteristics of hand tremor time series.

Tremor is classified into physiological, essential, and parkinsonian tremor by means of clinical criteria. The aim of our work was to extract quantitative features from the measurements of the acceleration of human postural hand tremor. Different mathematical methods were adopted and modified in order to separate these three types of tremor. Best discrimination between physiological and pathological tremors has been achieved by methods distinguishing nonlinear from linear behavior. On the other hand, methods separating different forms of nonlinear behavior have been found to be superior in discriminating parkinsonian and essential tremor. By these methods physiological and pathological tremors can be separated with an error rate below 20% and essential and parkinsonian tremor with an error rate below 10%. This may help to classify tremor time series by objective mathematical criteria and may increase the understanding of the pathophysiological differences underlying these kinds of tremor.

Analyzing the dynamics of hand tremor time series.

We investigate physiological, essential and parkinsonian hand tremor measured by the acceleration of the stretched hand. Methods from the theory of dynamical systems and from stochastics are used. It turns out that the physiological tremor can be described as a linear stochastic process, and that the parkinsonian tremor is nonlinear and deterministic, even chaotic. The essential tremor adopts a middle position, it is nonlinear and stochastic.

In vitro inhibition of protein catabolism by alpha 2-macroglobulin in plasma from a patient with posttraumatic acute renal failure.

Rapid proteolytic digestion of three subunits of phosphorylase kinase was shown in plasma ultrafiltrates from a patient who was admitted with multiple traumatic injuries, respiratory insufficiency, hemorrhagic shock and acute renal failure. The observed cleavage of phosphorylase kinase may be a consequence of protease-antiprotease imbalance. After an initial determination of 80 mg/dl the alpha 2-macroglobulin values were too low to be detected. Addition of purified alpha 2-macroglobulin to the ultrafiltrates resulted in complete inhibition of phosphorylase kinase digestion in vitro. Aprotinin did not inhibit proteolytic digestion. Daily dialysis did not ameliorate the observed protein catabolism of this patient. These findings may have clinical application in hypercatabolic states, if alpha 2-macroglobulin becomes available in a form suitable for human use.

Evidence for the participation of proteases on protein catabolism during hypercatabolic renal failure.

In ultrafiltrated plasma (molecular weight less than 50,000) obtained from four patients with multiple muscular trauma and acute post-traumatic renal failure, it was possible to verify a subcomponential specific digestion of the subunits alpha and gamma of phosphorylase kinase isolated from rabbit skeletal muscle. The activity of free proteolytic enzymes in ultrafiltrated plasma as well as an increase of plasma alpha 1-antitrypsin values were correlated with the severity and unfavourable course of the illness. In contrast, the plasma levels of alpha 2-macroglobulin were drastically lowered. The mean total protein concentration in the sera of patients with post-traumatic ARF was lowered, whereas the mean ultrafiltrate protein concentration was significantly enhanced. In ultrafiltrated plasma of two patients with hyperuricaemic ARF, three patients with ARF after drug over-dosage, one patient with acute pancreatic necrosis combined with acute renal failure and one patient with chronic pancreatitis, no proteolytic activity could be detected using phosphorylase kinase as substrate. Studies on the trypsin binding capacity of the plasma protease inhibitors revealed a significantly lowered level in patients with post-traumatic acute renal failure as compared to healthy controls, patients with chronic renal insufficiency and patients on regular dialysis treatment Proteolytic activity was found in ca. 100-fold concentrated diafiltrates (molecular weight greater than 10,000) of patients on regular dialysis treatment. Our data suggest a participation of proteases on protein catabolism in hypercatabolic states. Whilst the blood coagulation system can largely be excluded as a source of proteases, it is possible that proteolytic enzymes may be released from muscle lysosomes and/or macrophages after multiple muscular trauma.