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Biomedical subjects

R Dengler

Publications and source records attributed to R Dengler.

At least 109 records · Page 6Linked to original sources
PubMed1997

[Gilles de la Tourette syndrome. Effect of nicotine, alcohol and marihuana on clinical symptoms].

Gilles de la Tourette syndrome (TS) is a neuropsychiatric spectrum disorder of unknown etiology. While several studies have provided evidence that nicotine causes an improvement, only anecdotal reports suggest that alcohol and marijuana influence the symptomatology. Using a structured interview, we questioned a larger group of patients with Tourette syndrome (n = 47) about the use of nicotine, alcohol, and marijuana and their subjective experiences. Of 28 smoking patients only 2 (7%) reported a tic reduction when smoking. Of 35 patients drinking alcohol 24 (69%) noted an improvement. Thirteen patients reported the use of marijuana, of whom 11 (85%) noted a marked improvement. Our results provided strong evidence that the use of both alcohol and marijuana causes much more improvement in TS than nicotine smoking. We suggest that marijuana influences an assumed interaction between cannabinoid and dopamine receptors and, by this, influences the dopaminergic processes in basal ganglia and motor activity.

Adolescent↗
PubMed1997

Lifestyle surveys--the complete answer?

STUDY OBJECTIVES: These were as follows: to study incompleteness of data, herein called item non-response, generated by a self completion questionnaire; to identify the characteristics of item non-responders and the types of questions liable to high item non-response rates; and to discuss possible reasons for item non-response. DESIGN: Item non-response patterns in 12,307 responders (62%) to a representative postal survey based on a stratified sample drawn from family health services authorities' (FHSA) registers were investigated. MAIN OUTCOME MEASURES: Data were analysed for item non-response in three groups depending on when the questionnaire was returned (wave analysis). The overall completion rate of the questionnaire was examined and the natural logarithm of the proportion of completed questions was used as an outcome variable in multiple regression analysis. Item nonresponse to key questions and questions of different types was examined. RESULTS: Wave analysis: the overall completion rate of the questionnaire was 86% in questionnaires returned before the first reminder and 83%-84% in those sent back after subsequent reminders. Overall pattern of item non-response; respondents failed to complete a mean of 15% and a median of 10% of the questionnaire. All questions in the questionnaire had some item non-response, ranging from 1% to 85%. Completion rates were associated with gender, age, indicators of lower socioeconomic status, and general health status. Individual questions: particular types of questions were liable to have higher item non-response, for example, linked binary questions. CONCLUSIONS: Item non-response in population postal surveys is likely to present problems in the interpretation of data by introducing bias additional to that of total non-response. Item non-response does not increase greatly with later returns, suggesting that the quality of data across responses generated by two reminders is similar. There are obstacles to reducing item non-response, such as respondent error or socioeconomic and health characteristics of the general population, that cannot be totally overcome. However, the evidence that individuals tend to complete only options within questions that apply to them and their positive behaviour is useful information for those designing questionnaires and interpreting survey data.

Adolescent↗
PubMed1996

Human evoked potentials to long duration vibratory stimuli: role of muscle afferents.

Tonic vibratory stimuli of 1000 ms duration and different frequencies were delivered to muscles of the forearms of young human subjects. Evoked potentials (EPs) were recorded from 29 scalp channels and revealed phasic highly lateralised and focally distributed EPs during the first 100 ms of the recording epoch that could be adequately modelled with a single point dipole source located in the vicinity of the central sulcus contralateral to the stimulated arm. A later negativity with an onset of about 400 ms and a duration of about 800 ms was found to be symmetrically distributed over fronto-central regions. This negativity is interpreted in terms of cortical activation beyond the primary sensory fields and could be related to the kinaesthetic phenomena experienced during muscle vibration.

Adult↗
PubMed1996

Muscle fatigue, lactate, and pyruvate in mitochondrial myopathy with progressive external ophthalmoplegia.

We studied muscle fatigue and serum lactate and pyruvate levels in 20 patients with mitochondrial myopathy with progressive external ophthalmoplegia (PEO). Fatigue was assessed in the adductor pollicis muscle (AP) using a low-intensity exercise protocol (20 min). Forces (TFs) and relaxation times of ulnar nerve evoked twitches, compound muscle action potentials (CMAPs), and maximal voluntary contractions (MVCs) were monitored. Serum lactate and pyruvate levels were independently measured at rest and after exercise on a bicycle (15 min, 30 W). Most patients showed abnormal fatigue of the AP with a reduction of TFs and MVCs and normal CMAPs. The reduced TFs were significantly correlated with lactate levels at rest (r= - 0.60, P<0.05) and less so with those after exercise (r=- 0.47,P<0.05). Pyruvate levels revealed a similar correlation although they were widely scattered. We conclude that abnormal fatigue in PEO is metabolic, is localized beyond the muscle fiber membrane, and involves the electrome-chanical coupling and the contractile apparatus. Serum lactate levels at rest are good predictors of fatigue in PEO.

Action Potentials↗
PubMed1996

An autosomal-recessive congenital myasthenic syndrome with tubular aggregates in a Libyan family.

We studied a Libyan family in which five out of seven siblings have had slowly progressive limb-girdle weakness accentuated by exercise since childhood. Ptosis or ophthalmoplegia were not observed. Pronounced decremental electromyographic responses on 3 Hz stimulation indicated the presence of a defect of neuromuscular transmission. Repeated testing for acetylcholine receptor antibodies was negative. Muscle biopsy revealed tubular aggregates in 34% of the type 2 muscle fibers. Our observation illustrates the wide clinical spectrum of congenital myasthenic syndromes.

Adult↗
PubMed1996

Adolescents' use of prescribed drugs and over-the-counter preparations.

BACKGROUND: The objectives of this paper are to present data on the self-reported use of prescribed and over-the-counter drugs among young people aged 11-12 and 14-15 years and to examine factors associated with the use of prescribed drugs, over-the-counter painkillers and cough and cold treatments. METHOD: Data were collected from a representative sample of pupils aged 11-12 years old and 14-15 years old attending 85 schools in Trent Region. Results are based on replies from approximately 8500 pupils in each year group. Pupils were asked to self-report usage by ticking a list of prescribed and non-prescribed drugs or medicines. RESULTS: Girls aged 14-15 years are more likely than others to have used at least one of the drugs in the previous week, with 40 per cent of girls in this age group having used a non-prescribed painkiller. Young people with a long-term illness or previous injuries are more likely to report having used prescribed drugs and/or over-the-counter painkillers. Family car-ownership, a proxy for socio-economic status, is not associated with the use of those drugs examined in more detail. CONCLUSIONS: The levels of use of over-the-counter drugs, particularly those with potential side effects, indicate that further studies are needed to examine patterns of use in more detail and that health education about self-medication is appropriate among young people aged 11-12 years and above.

Adolescent↗
PubMed1996

Methods for onset detection of voluntary motor responses in tremor patients.

Accurate onset detection of the voluntary response is a prerequisite in reaction time studies when used in investigations on human motor control. The detection algorithm required performs a transformation of the continuous physical signal (e.g., force, movement) containing the response into a discrete event from which the reaction time (RT) is derived. Therefore, RT always comprises both the cognitive and/or motor delay component imaging the duration of the initiation process conducted by the sensorimotor system and, in addition, some spurious delay caused by the detection algorithm. As a standard method, onset detection is realized by the measurement device itself (e.g., the release of a micro switch) by defining the response onset as the point where the observed signal passes a certain threshold. Thus, weak and abnormal response profiles which are typical for a variety of central motor disorders (e.g., Parkinson's disease) may introduce high RT variability as well as systematic errors. The aim of this study was to improve accuracy of onset detection by application of an appropriate filter to the measured signal before entering the final decision stage. Three algorithms (lowpass differentiator, inverse filter, linear autoregressive (AR) predictor) were implemented and tested on simulated and real data under both on-line and off-line conditions with special interest to the influence of quasi-periodic background activity like tremor. It is shown that a significant improvement in onset detection accuracy, compared with the simple switch, can be achieved by using appropriate low order adaptive filters with the AR-predictor being the most efficient solution.

Algorithms↗
PubMed1995

Tremor as a factor in prolonged reaction times of parkinsonian patients.

Prolonged reaction times and tremor are symptoms of Parkinson's disease (PD). Recently, we showed the existence of a systematic phase relationship between tremor-at-rest and the onset of voluntary motor responses in PD patients. In the present study we investigated whether this phase relationship contributes to the prolongation of reaction time in PD. Eight PD patients with prominent tremor-at-rest and five age-matched controls performed rapid stimulus-evoked index finger abductions under isometric conditions. Force and surface electromyogram (EMG) signals from first dorsal interosseus muscle were recorded and analyzed off-line by means of automatic routines. Reaction times of PD patients exhibited a significant dependence of mean values and variability on the current tremor phase at the onset of the voluntary motor response. Responses with an onset of contraction during the beginning of an EMG tremor burst were substantially delayed (on average 50 ms) and showed more variability in comparison to responses initiated at later times in the tremor cycle. This effect can be modeled by a simple gating process splitting the tremor cycle into two different system states that supports and inhibits the initiation of voluntary motor responses, respectively. We conclude that attraction of voluntary motor initiation to the tremor oscillator clearly contributes to prolongation of reaction time in PD.

Aged↗
PubMed1995

Human motor units studied by intramuscular microstimulation.

We recorded twitch parameters of motor units of the human first dorsal interosseus muscle applying low-rate intramuscular microstimulation of motor axons (IMS) or spike-triggered averaging (STA). The values of contraction time, half-relaxation time and maximal rate of rise of force were significantly smaller in the STA studies. The reduction corresponded to the effect expected from partial twitch fusion. Twitch amplitudes, however, were not smaller than those in the IMS studies, indicating that other factors, such as motor unit synchronization, compensate for the effects of partial fusion.

Adult↗
PubMed1995

Immunocytochemical and flow cytometric detection of proteinase 3 (myeloblastin) in normal and leukaemic myeloid cells.

Proteinase 3 (P3) is a serine proteinase present in the primary granules of neutrophils. We have investigated the expression of this protein in samples of bone marrow from healthy individuals and patients with different types of leukaemias by using immunocytochemical staining and flow cytometric quantitation. In normal bone marrow the enzyme was found in promyelocytes, myelocytes, metamyelocytes, band forms and polymorphonuclear neutrophils, correlating with the synthesis of neutrophil serine proteinases during myeloid maturation. No staining was found within the lymphoid, erythroid and megakaryocytic lineage. In the leukaemic samples, only those of acute myeloid and chronic myeloid leukaemia patients were labelled with the antiproteinase 3 antibody. Cases of acute lymphoblastic and chronic lymphocytic leukaemia, as well as other malignant lymphomas, were consistently negative, indicating that P3 may be used as a specific marker for the discrimination between myeloid and lymphoid leukaemias. In addition, immunoreactivity of myeloperoxidase (MPO) was investigated and the expression of P3 and MPO correlated with the French-American-British (FAB) classification. P3 was not detected in minimally differentiated M0 and M1 cases but was in predominantly labelled cells of M2 and M3 subtypes plus half of the M4 and one out of six M5 cases but not those of M6. These findings correspond to the differentiation stage in which P3 is expressed and stored in the primary granules. Therefore the enzyme may also be used as an adjunct to the classic morphological and cytochemical methods to elucidate further the stage at which the differentiation arrest of the leukaemic clone has occurred.

Acute Disease↗
PubMed1995

Limited proteolysis of alpha 1-proteinase inhibitor (alpha 1-PI) in acute leukemia: studies on the resulting fragments and implication for the structure of the inactivated inhibitor.

In patients with acute myeloid leukemia, a 41 kDa glycoprotein appears in the urine during remission induction chemotherapy. We have recently reported on the isolation and preliminary characterization of this protein and the generation of specific monoclonal antibodies which showed that it is a proteolytically modified form of alpha 1-proteinase inhibitor (Dengler et al., 1992, Biol. Chem. Hoppe-Seyler 373, 581-588). In the paper presented here, results from further characterization experiments as well as from studies on the effects of proteolysis on the conformation and the resulting functional properties of the truncated inhibitor are reported. N-terminal amino acid sequence analysis showed that proteolysis has occurred in the N-terminal part as well as in the reactive site loop of alpha 1-PI. The resulting core protein of 41 kDa is composed of approximately 324 amino acid residues with the C-terminus located close to Lys343 of alpha 1-PI.A 4 kDa peptide remaining bound to this fragment throughout the entire purification procedure could be separated by SDS treatment. N- and C-terminal sequence analysis of this peptide after isolation by gel filtration showed that it is comprised of residues Ile359 up to Lys394, thus representing the peptide located C-terminal to the reactive site loop of alpha 1-PI. Transverse urea gradient gel electrophoresis indicates that the proteolyzed inhibitor is in the thermodynamically stable, relaxed (R)-conformation known for proteinase-complexed and cleaved serpins. The truncated inhibitor exhibits no chemotactic activity towards neutrophils when tested in a standard assay.

Amino Acid Sequence↗