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Biomedical subjects

R Dengler

Publications and source records attributed to R Dengler.

At least 127 records · Page 7Linked to original sources
PubMed1995

[Clinical aspects and conservative therapy of Parkinson disease].

Parkinson's disease is essentially motor. The core symptoms comprise akinesia, rigidity and tremor. Concomitantly, signs of autonomic, cognitive and affective disturbances may be found. The disease progresses slowly and, without treatment, ultimately results in disability and loss of independence. The symptoms can be controlled for a long time by pharmacotherapy. Dopaminergic drugs such as L-DOPA, dopaminreceptor agonists, and MAO-B- and COMT-blockers can essentially improve most of the symptoms. The tremor may be alleviated by central anticholinergic drugs. With time, however, unwanted side effects such as "end of dose akinesia", "on-off phenomena", hyperkinesis and exogenous psychosis come into play. Therefore, pharmacological treatment becomes very complex in the late stages of the disease and the unwanted side effects can no longer be sufficiently controlled. It is not clear whether conservative approaches will be ever able to cope with these problems. This explains the search for novel treatment strategies, e.g. neurotransplantation, stereotaxic lesion of the subthalamic nucleus or stimulation techniques.

Antiparkinson Agents↗
PubMed1995

Urinary excretion of proteolyzed alpha1-antitrypsin: specificity, quantitation, and relation to therapy response in patients with acute myeloid leukemia.

During remission induction chemotherapy, a 41-kDa cleavage product of alpha1-antitrypsin (alpha1-AT41) can be found in the urine of patients with acute myeloid leukemia. By using immunoblotting with antibodies against this protein, 27 patients with acute myeloid leukemia were screened for the excretion of this fragment and the amount of alpha1-AT41 compared with treatment response assessed by therapy-induced cytoreduction in the bone marrow and time to reach remission. Patients with acute lymphoblastic leukemia, malignant lymphomas, and solid tumors receiving chemotherapy, patients with nonmalignant diseases like sepsis and kidney dysfunction, and healthy subjects were probed to evaluate the specificity of this phenomenon. In 74% of the acute myeloid leukemia patients, the truncated inhibitor was detected. Mean concentration of peak excretion was found to be 6.7 microgram/mg creatinine (range, 1.1-41 microgram/mg). Among the patients treated with induction chemotherapy, those who responded completely (<5% residual marrow blast cells) exhibited significantly higher alpha1-AT41 concentrations than the nonresponders (P < 0.03). Patients who showed a partial response (6-25% residual blasts) excreted intermediate values of the protein. The probability of median time to reach remission was 40 days in patients excreting the truncated inhibitor in measurable amounts compared to 100 days in patients negative for alpha1-AT41 (P < 0.02). The 41-kDa fragment was also found in one of 10 patients with acute lymphoblastic leukemia and in 3 of 18 lymphoma patients but not in those with solid tumors, infections, or kidney disease or in healthy individuals.

Adult↗
PubMed1994

Central and peripheral nervous system conduction in mitochondrial myopathy with chronic progressive external ophthalmoplegia.

Involvement of the peripheral and central nervous systems in mitochondrial myopathy with chronic progressive external ophthalmoplegia (CPEO) has been demonstrated clinically and electrophysiologically. Systematic electrophysiological investigations of the peripheral and central nervous systems, particularly of cortico-spinal tract function, however, are not available. We studied peripheral and central nervous system involvement in 28 patients with histologically and biochemically proven mitochondrial CPEO by motor and sensory nerve conduction tests, by somatosensory, auditory and visual evoked potentials and, for the first time, by transcranial magnetic stimulation. Nervous system involvement could be demonstrated in 24 patients, affecting the peripheral and central nervous systems in 18 and 10 patients, respectively. Evidence of cortico-spinal tract involvement was found in 4 patients, which was clinically expected in only 2. Therefore, dysfunction of the cortico-spinal tract in mitochondrial CPEO may occur more frequently than so far assumed. Generally, electrophysiological tests serve as valuable supplements to clinical examination in patients with mitochondrial CPEO and may be especially helpful in therapeutic studies, i.e., coenzyme Q administration.

Adolescent↗
PubMed1994

Assessment of human motor unit twitches--a comparison of spike-triggered averaging and intramuscular microstimulation.

We recorded twitches of single motor units (MUs) in the human first dorsal interosseus muscle using either spike-triggered averaging (STA; 236 MUs in 12 normal subjects) or low-rate intramuscular microstimulation of motor axons (IMS; 200 MUs in 20 normal subjects). We analysed twitch force (TF), maximal rate of rise of force (MRRF), contraction time (CT) and half-relaxation time (HRT). MRRF, CT and HRT were significantly smaller with STA than with IMS whereas TFs were fairly similar. Higher stimulus rates (up to 14 Hz) in IMS resembling the voluntary MU firing rates in STA were associated with a decrease of all twitch parameters because of partial fusion of the twitches (20 MUs). Concerning MRRF, CT and HRT, the reduced values matched those obtained by STA, suggesting that the underestimation of these parameters in STA can be mainly attributed to partial fusion. The reduction of TF with high rate IMS but not with STA reveals that other factors such as MU synchronization and non-linear force summation of MU contractions must counteract the effects of partial fusion in STA. We conclude that both STA and IMS are appropriate for assessing TFs in man while the time-dependent parameters MRRF, CT and HRT will be underestimated with STA.

Adult↗
PubMed1994

Results from a lifestyle survey: Trent health.

The objective of this work was to examine the efficiency of a postal survey in generating data relevant to Trent Regional Health Authority's need for baseline measures as indicators for health promotion, as specified in its strategy for health promotion. A representative sample, by District, was identified using Family Health Service Authority registers as the sampling frame, stratified by age (16-70 years) and gender. Data were collected from the resulting sample of 21,603 using a self-completion illustrated questionnaire. Delivery was postal with two reminders. Prepaid envelopes were supplied for returns. Questions about lifestyle, e.g. behaviour, attitudes and beliefs about smoking. The survey took place in each of the 12 Districts of Trent Region, the total population of which is over 4.5 million. The main outcome measures were behaviour, attitudes and beliefs about health by age and gender and by social class. The response was 61% after exclusions. Young males were under-represented in response. Sixty four per cent of respondents were non-smokers, 14% took optimal exercise on a monthly basis and 15% never drank alcohol. In the week prior to the study males were more likely to have drunk more than the recommended units of alcohol (24%) than women (9%). Over two-thirds of respondents (72%) had three key elements of social support. The postal survey generated data directly relevant to indicators embedded within Trent Health's health promotion strategy. Across the Region it was possible to examine patterns of response by age, gender and by social class. Data were adequate as baseline measures and repeat studies will monitor change. However, data are biased with sub-groups under-represented. In addition, non-responders are known to be different from responders. Data are therefore limited, but can be used to describe general patterns amongst responders. Other methods of data collection are required for the collection of more sensitive and/or qualitative data.

Adolescent↗
PubMed1994

123I-IBZM SPECT: reconstruction methodology and results in parkinsonism and dystonia.

In 58 patients with Parkinsonism or dystonia striatal dopamine D2 receptors were investigated using 123I-iodobenzamide (123I-IBZM) single-photon emission computed tomography (SPECT). The influence of SPECT reconstruction methodology on semiquantification and the clinical value of 123I-IBZM SPECT were evaluated. Delineation of the striatal uptake and striatum/frontal cortex (ST/FC) ratios were improved by the use of compensation procedures for scatter and attenuation as well as the choice of an adequate filter. Satisfactory results were achieved using a Metz prefilter with a comparatively high order number (i.e. high cut-off and low suppression of higher frequencies via roll-off). Regarding clinical diagnoses it was not possible to differentiate between advanced idiopathic Parkinson's disease (IP) and Parkinsonism of other aetiology (OP) on the basis of 123I-IBZM SPECT. But patients with IP and favourable response to L-Dopa showed significantly higher ST/FC ratios than those with fluctuating response. In patients with dystonia ST/FC ratios were significantly higher compared to patients with IP or OP.

Adult↗
PubMed1993

Activation of high-threshold motor units in man by transcranial magnetic stimulation.

Motor units (MUs) with low voluntary recruitment thresholds are the first to be activated by transcranial magnetic stimulation. It is not clear, however, if high-threshold MUs can also be activated and if they contribute to motor evoked potentials (MEPs). We therefore studied 11 high-threshold motor units in the first dorsal interosseous muscle of 11 healthy subjects. Voluntary recruitment thresholds ranged from 22 to 41% (29.5 +/- 5.6%; mean +/- S.D.) of maximal muscle force. When MUs were driven at their recruitment thresholds, transcranial magnetic stimuli were applied to the vertex. Peri-stimulus time histograms of MU discharges were constructed. All MUs studied revealed a period of increased firing probability at 19-27 ms after the stimulus (primary peak). Stimulus intensities were lower by 10-57% of the maximal stimulator output than required to produce near maximal MEPs in conventional surface EMG recordings in the same subjects. We conclude that high-threshold MUs can be activated by transcranial magnetic stimulation and that they contribute to conventionally recorded MEPs.

Adult↗
PubMed1993

Impact of a postcard versus a questionnaire as a first reminder in a postal lifestyle survey.

STUDY OBJECTIVE: The study aimed to consider the impact of two different types of reminder on response rates and costs in a postal survey. DESIGN: The study was a cross sectional survey. A self-completion lifestyle questionnaire was used. Those who did not respond after the initial mailing were randomly allocated to receive either a postcard or questionnaire as a first reminder. All outstanding non-responders received a questionnaire as a second reminder. SUBJECTS: A representative sample of 698 adults aged 16-70 was used, drawn from a family health services authority register. MAIN RESULTS: Postcard reminders were as effective as questionnaire reminders in increasing response whether one or two reminders are sent. The costs per response were calculated. Two questionnaires as reminders were found to be 1.7 times more expensive than a postcard plus questionnaire. Including the initial mailing, the cost per response using all questionnaires was 1.3 times the cost when a postcard was used for the first reminder. CONCLUSIONS: To increase the response to a postal survey effectively and economically, two reminders should be sent--first a postcard and then a questionnaire.

Attitude to Health↗
PubMed1993

Relationship between tremor and the onset of rapid voluntary contraction in Parkinson's disease.

It has been suggested that initiation of voluntary movement in Parkinson's disease (PD) is synchronous with tremor beats. This hypothesis was tested by examining quantitatively the onset of voluntary contraction in relation to the tremor cycle. Five PD patients with tremor at rest produced fast isometric abduction of the index finger in reaction time and self-paced trials. For each trial, the time interval from last tremor peak to contraction onset was evaluated and its frequency distribution was compared with proposed statistical models. It was found that patients most often initiated contractions during the descending phase of the tremor oscillation and that the phasic EMG burst most commonly occurred after the mid-point of the EMG tremor cycle in both self-paced and reaction time conditions. These results indicate that voluntary contraction is not initiated arbitrarily with respect to the tremor oscillation. Rather, there is a systematic phase relationship between the onset of the voluntary response and tremor. Thus attraction of voluntary movement to the tremor oscillator in PD results from abnormally synchronised motor units and failure to activate the motor neuron pool voluntarily soon after the tremor discharge.

Aged↗
PubMed1992

F waves and motor unit size.

M responses and twitch contractions were evoked in single motor units (MUs) of the first dorsal interosseus muscle by intramuscular microstimulation of motor axons. Two-hundred nine MUs were studied in 21 subjects. Thirty-five MUs (17%) showed F waves in addition to M responses. Twitch force was used to provide an indirect measure of MU size; additionally, twitch contraction time was measured. There was no select group of MUs generating F waves with regard to the above contraction parameters. However, four of five MUs with very high twitch forces, above 70 mN, generated F waves. We conclude that MUs of all sizes produce F waves with similar probability. Only few MUs with very strong twitch forces, i.e., very large MUs, may be more subject to F-wave production and may be involved in the generation of the so-called repeater F waves.

Action Potentials↗
PubMed1992

Local botulinum toxin in the treatment of spastic drop foot.

Ten patients with spastic drop foot were treated by local injections of botulinum toxin A (botulinum toxin A haemagglutinin complex). The purpose was to improve stance and gait and/or to facilitate physiotherapy and patient care. Various calf muscles were injected using EMG guidance. The average dose used was 23 ng. Prior to and 4 weeks after treatment, positions of the upper and lower ankle joint at rest and the corresponding end positions of passive and active movement were determined. In addition, changes of spasticity and pain, the transmission phenomenon and stance and gait were evaluated. Most patients showed improvement of some aspects of the spastic drop foot. Positions of the upper and lower ankle joint were improved in most of the patients, as were the other parameters examined. Except for weakness of the injected muscles no side-effects were observed. The results appear promising and may be optimized in further trials by using higher doses of the toxin.

Adolescent↗
PubMed1992

Parameters of human motor unit twitches obtained by intramuscular microstimulation.

Intramuscular microstimulation of motor axons was used to study twitch responses of 209 motor units (MUs) in the first dorsal interosseus muscle (FDI) of 20 normal subjects. Twitch peak force (TF), maximum rate of rise of force (MRRF), contraction time (CT) and one-half relaxation time (HRT) were determined. The distributions of TF (mean 16.0 mN, median 10.3 mN) and MRRF (mean 0.88 N s-1, median 0.66 N s-1) were skewed to the right with the majority of the values lying in the lower ranges, whereas CT (mean 63 ms, median 62 ms) and HRT (mean 61 ms, median 58 ms) were approximately normally distributed. TF was significantly correlated with MRRF, but not with CT in contrast with studies of cat gastrocnemius muscle. TF values were similar to those obtained by spike-triggered averaging in the same muscle. The method proved to be reliable and appropriate for use in patients. Examples of MU twitch parameters from three patients with chronic partial denervation of the FDI are described.

Adult↗
PubMed1992

Proteolytic inactivation of alpha 1-proteinase inhibitor in vivo: detection, characterization and quantitation of the main fragment excreted in the urine of leukemia patients.

During the search for a therapy response parameter in patients with acute myeloid leukemia, we observed the appearance of a 41 kDa glycoprotein band in the urines of these patients under therapy. To investigate the nature of this molecule and to develop a specific detection system, the protein was isolated and antibodies were raised. Urines and sera of patients and healthy subjects were screened for crossreacting proteins by immunoblotting. Only the leukemia patients showed the urinary 41 kDa protein plus a 53 kDa band. In all sera, including those from healthy donors, a 53 kDa protein was intensely stained. Isolation of the plasma protein and sequence analysis of the urinary protein revealed that alpha 1-proteinase inhibitor is the crossreacting plasma protein and that the 41 kDa molecule is proteolytically modified alpha 1-PI, which has lost its antitryptic activity. Cleavage occurred in the N-terminal part as well as in the reactive site loop of the inhibitor. The 41 kDa truncated inhibitor was also found in the leukemic blast cells. A densitometric method is described for the quantitation of the molecule in the nanomolar range.

Amino Acid Sequence↗
PubMed1992

[Non-neoplastic Lambert-Eaton syndrome. A frequently missed diagnosis?].

Three cases of non-paraneoplastic Lambert-Eaton syndrome are presented. There remains no indication of neoplasm after illnesses of nine years, 36 months and 20 months respectively. In one case, the syndrome became manifest during chloroquine medication. The cause of the proximal lower limb weakness had not been recognized during previous hospital stays, although in retrospect indications of a Lambert-Eaton syndrome were found in the electrophysiological tracings. The conclusive diagnosis was made electrophysiologically. The leading sign was an abnormally low compound muscle action potential evoked by supramaximal nerve stimulation. Furthermore, the characteristic increase of amplitude of the compound muscle potential after maximal voluntary contraction or at high frequency stimulation (20 Hz) could be demonstrated. It is concluded that the non-paraneoplastic Lambert-Eaton myasthenic syndrome may frequently remain unrecognized.

Adult↗
PubMed1992

[Is the origin of the F-wave dependent on the magnitude of the motor unit?].

It is still unknown why only few motor units (MUs) generate F-waves in response to supramaximal stimulation of a motor nerve. Therefore we investigated whether the F wave production might depend on MU-size. According to the size principle of Henneman we used the twitch force as indirect measure of MU-size. MU twitch force was determined applying the technique of intramuscular microstimulation of single motor axons. 127 MUs were analysed in 16 normal subjects. F-waves were observed in 35 MUs (27%). It was found that MUs of different sizes produced F-waves with approximately the same probability. Obviously size is not a relevant factor for the capability of a MU to produce F-waves. Only the few very large MUs of a pool may have an increased tendency to produce F-waves because four of five MUs with extremely large twitch forces (> 70 mN) generated F-waves.

Adult↗