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Biomedical subjects

A Haass

Publications and source records attributed to A Haass.

At least 73 records · Page 4Linked to original sources
PubMed1985

Antimyotonic therapy with tocainide under ECG control in the myotonic dystrophy of Curschmann-Steinert.

Ten patients suffering from advanced myotonic dystrophy with severe myotonic symptoms were treated with 800-1200 mg/day of the anti-arrhythmic drug tocainide (Xylotocan). All patients reported a marked subjective improvement of myotonia, which was confirmed by objective tests. Except for a slight QT-prolongation in one patient, the ECG was not significantly altered by the treatment. Twenty-four-hour ECG after treatment disclosed that pre-existing ventricular arrhythmia disappeared in three cases. The occurrence of complex ventricular arrhythmia in two patients under treatment was not necessarily due to specific effects of the drug but might be explained by the high spontaneous variability of rhythm disorders. In these patients suffering from myotonic dystrophy with typical cardiomyopathy no deleterious effects of the drug were observed, especially no cardiac arrhythmias which would have necessitated interruption of treatment. Therefore, the authors recommend symptomatic therapy with tocainide for myotonia and paramyotonia congenita, as well as in myotonic dystrophy patients suffering from marked myotonic stiffness. ECG and 24-h ECG should be carefully recorded as necessary in any treatment with anti-arrhythmic drugs.

Adult↗
PubMed1979

Influence of temperature on isometric contraction and passive muscular tension in paramyotonia congenita (Eulenburg).

Four patients without symptoms of episodic hyperkalemic weakness from two families with paramyotonia congenita (Eulenburg) are described. 1. Maximum voluntary muscle contraction of the upper and lower arm was studied under isometric conditions at different temperatures. If the temperature was lowered stepwise, distinct paresis occured at 32--31 degrees C which increased with the amount of muscular effort. The upper arm muscles, however, developed weakness gradually after cooling. 2. During cooling of the resting muscle, the EMG showed dense spontaneous activity of the fibrillary type, which decreased again at about 30 degrees C. It can be assumed that in paramyotonia congenita cooling produces muscle cell membrane depolarization which at a critical level causes the firing of action potentials and finally muscular paresis. 3. Increasing muscular stiffness can be interpreted as abnormally slow muscular relaxation after isometric contraction. In the forearm muscles the time to 3/4 relaxation after cooling was about six times normal, in the upper arm muscles only two times normal. As an additional parameter the mechanical resistance to passive stretching of a muscle has been studied. This passive muscular tension increased simultaneously with the onset of weakness. 4. The close relation between weakness and stiffness suggest that both symptoms are caused by the same basic defect which is probably located in the sarcolemma. It is suggested that a defect of the sodium channel causes a cooling-dependent increase in sodium conductance. Raised intracellular sodium causes in the first place membrane depolarization, and in the second place depression of calcium reuptake through competition by sodium for calcium binding sites. This would explain muscle stiffness and delayed relaxation as well.

Arm↗
PubMed1978

Fenoterol precipitating myotonia in a minimally affected case of recessive myotonia congenita.

Fenoterol is used in patients with premature labor to delay delivery. A young women treated with fenoterol developed severe generalized myotonia. Symptoms disappeared after medication had been stopped. In a later study myotonic discharges were found electromyographically in the muscles of the patient and her brother. Both suffered from subclinical recessive myotonia congenita (Becker). A heterozygous manifestation may be supposed.

Adult↗
PubMed1978

Transient muscular weakness in severe recessive myotonia congenita. Improvement of isometric muscle force by drugs relieving myotomic stiffness.

The maximum force of voluntary muscle contraction was registered under isometric conditions in nine patients with recessive myotonia congenita. The recordings were made on the upper arm. Five patients with severe myotonia had a transient weakness after muscle rest. Electromyographic registrations with wire electrodes showed that the myotonic muscle fiber discharges disappeared during the transient weakness. Medication improving myotonic stiffness also improved the weakness. The cause of transient weakness seems to be similar to that of myotonic stiffness. It is known that an increasing depolarization of the myotonic muscle fiber membrane leads to the myotonic discharges and myotonic stiffness. In severe myotonia the progressing depolarization could cause a loss of excitability of the muscle fiber membrane and thereby a transient paresis of a more or less large number of muscle fibers.

Adult↗
PubMed1975

Effects of lanthanum, calcium and barium on the resting membrane resistance of guinea-pig papillary muscles.

1. The influence of some cations upon the effective resting membranes resistance of guinea-pig isolated papillary muscles was investigated by means of the double sucrose-gap method. 2. Elevated Ca Concentrations and, to a higher degree La, increased the membrane resistance. The current-voltage relationship, however, revealed a marked difference. The action of Ca was restricted to cathodal pulses, whereas La decreased the permeability of both the hyper-and depolarized membrane. 3. With respect to the resting membrane properties La mimicked the action of Ba and of altered K concentrations, both of which are known to exert their effects mainly by changing the K permeability. 4. Taking into account the different actions of La and Ca on the current-voltage relationship and on the transmembrane potentials, it is suggested that in the resting state La, in contrast to Ca, mainly influences the K permeability. This difference should be considered when La is used as an agent for studying the cellular Ca exchange in heart muscle.

Action Potentials↗
PubMedDate not supplied

Clinical study of paramyotonia congenita with and without myotonia in a warm environment.

Fourteen patients with paramyotonia congenita were examined clinically. Patients of 3 families had no myotonia in a warm environment while in a cold environment they developed paradoxical myotonia (myotonia aggravated by repeated muscle contraction). Patients of a 4th family had myotonia associated with after-activity in a warm environment which was not paradoxical. This myotonia was aggravated by cooling. In a warm environment the resting muscles of all patients showed no spontaneous electromyographic activity except for occasional myotonic runs. On cooling, spontaneous fibrillations developed. This was most intense at 32 degrees C-28 degrees C (muscle temperature). On deeper cooling it ceased. In contrast, 5 patients with myotonia congenita did not show such activity during cooling. In all paramyotonic patients cooling (30 degrees C-25 degrees C) produced muscle paralysis, which outlasted rewarming by several hours. At 32 degrees C-30 degrees C muscle relaxation was slowed. Recording of electromyographic activity and isometric contractions of the long finger flexors during cooling revealed that the slowing of muscle relaxation in paramyotonia is not as closely linked to after-activity as is the slowing of muscle relaxation in myotonia congenita.

Adolescent↗
PubMedDate not supplied

Membrane defects in paramyotonia congenita with and without myotonia in a warm environment.

Three patients with paramyotonia congenita and 3 control persons were biopsied for an in vitro investigation of the sarcolemmal membrane parameters and of the contractile properties of paramyotonic muscle. At 37 degrees C, paramyotonic muscle fibers had normal resting potentials, but on cooling to 27 degrees C they depolarized. Depolarization to -60 mV caused spontaneous activity, and further depolarization to -40 mV caused inexcitability. Depolarization could be prevented by the application of tetrodotoxin, a finding suggesting a defect in the Na channels. Analysis of the membrane current densities using voltage clamps with 3 microelectrodes revealed that in paramyotonic patients at 37 degrees C all component conductances were normal, except for a decreased Cl conductance in the patient who had myotonia in a warm environment. At 27 degrees C, the Na and Cl conductances were abnormally high. The K conductance was always normal. The results explain the clinical symptoms of weakness and paralysis. Potassium- and caffeine-contracture experiments gave normal results. The clinical symptom of paramyotonic stiffness, therefore, has not been explained by these studies.

Action Potentials↗
PubMedDate not supplied

Neurologic manifestation and classification of borreliosis.

The neurologic symptoms of borreliosis can be classified to give distinct clinical pictures. The exact clinical characterisation allows an unambiguous and applicable classification of the different neurologic manifestations to be made. Due to high background seroprevalence of anti-Borrelia antibodies this classification is crucial for diagnosis. The most frequent neurologic manifestation is meningopolyradiculitis. It shows a typical pattern of symptoms, yet for differential diagnosis the crucial symptoms are the severe pains and the paresis of cranial nerves. In up to 10% of these patients no specific intrathecal antibody production was identified due to the time factor. Intrathecal antibody production cannot therefore be considered as the exclusive criterium for neuroborreliosis.

Antibodies, Bacterial↗
PubMedDate not supplied

Tick-borne encephalitis diagnosis in patients with inflammatory changes in the cerebrospinal fluid in a region with very low prevalence.

Tick-borne encephalitis (TBE)-IgG antibodies are used for the serologic detection of antigen contact caused by TBE infection or immunization. In the present study, enzyme-linked immune sorbent assay (ELISA) results from a group of patients with inflammatory changes in the cerebrospinal fluid (CSF) were re-examined using Western blot technology. The result of the TBE-IgG-ELISA was positive in 47 of the 904 sera samples tested. Retesting the sera with a Western blot confirmed this result in only 31.8% of the positive cases. In 134 of the 904 sera, the ELISA result was borderline. In 5.5% of these sera, the Western blot reacted specifically. The remaining 723 sera samples tested negative with the ELISA. Of these sera, 15 were selected randomly and retested with the Western blot; none of them tested positive. The high number of false positive ELISA results can be explained by the highly selected group of patients and the low prevalence of TBE in the region studied. In patients with meningitis or encephalitis with positive ELISA results and uncharacteristic clinical symptoms, the treating physician should consider the possibility of nonspecific reactions involving inflammatory mediators or cross-reactivity with other flaviviruses. The ELISA-mediated diagnosis of TBE should therefore be verified by means of the patient's history and clinical symptoms, as well as further serologic tests including the Western blot, the hemagglutination test and the neutralization test.

Blood↗