Prospective analysis of gait characteristics in chronic inflammatory demyelinating polyradiculoneuropathy.

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is a disorder that may lead to functional impairment, including gait abnormalities. Our aim was to analyze gait characteristics in patients with CIDP compared to healthy controls (HC). Moreover, we sought to determine changes of gait parameters after six-month follow-up period. Twenty-four patients with CIDP and 24 HCs performed basic walking task, dual-motor task, dual-mental task, and combined task using the same GAITRite system. Lower limb MRC-SS and lower limb INCAT disability score were assessed. Fourteen patients were retested after six months. Majority of gait parameters showed significant differences in all experimental conditions when compared between CIDP and HCs. The most consistent findings in CIDP were shorter stride length (SL), prolonged cycle time (CT) and double support time (DS), as well as increased variation of SL and of swing time (ST) (p < 0.05). During follow-up, INCAT improved in nine (64.3%) of 14 patients and MRC-SS improved in eight (57.1%) patients. Six-month changes of CT and its variation during combined task significantly differentiated patients with improved vs. non-improved INCAT (p < 0.05). In conclusion, patients with CIDP had slower gait with prolonged DS and with shorter SL compared to HCs. Increased variation of SL and of ST in CIDP may suggest a potential risk for instability and falls. Shorter CT duration and less CT variation during time correlated well with improvement in disability.

Menopause-specific Quality of Life Questionnaire: factor and Rasch analytic approach.

OBJECTIVE: The study aimed to assess the psychometric properties of the Menopause-specific Quality of Life Questionnaire (MENQOL) in Serbian climacteric women. METHODS: Two hundred mid-aged (40-65 years) women filled out a general sociodemographic and medical questionnaire, the MENQOL, the Short Form-36 questionnaire (SF-36), and Beck's Depression Inventory (BDI). The MENQOL was translated according to recommended methodology and its psychometric properties (internal consistency, discriminant, construct and criterion validity, factor and Rasch analyses) were assessed. RESULTS: Cronbach's alpha coefficient for the Serbian MENQOL was 0.957 (Vasomotor =0.917, Psychosocial =0.907, Physical =0.928, Sexual =0.913). Corrected item-total correlation coefficients were >0.50 for all items. Factor analysis extracted six domains with total variance of 72.02%. Beside the four original domains, two new domains were observed: Attractiveness and Pain. Factor loadings for all items were appropriate (>0.4). The MENQOL correlated with the SF-36 and BDI total scores, suggesting good criterion validity. Rasch analysis showed adequate reliability (item =0.91; person =0.79) and separation (item =1.95; person =3.21) indexes, proving good reproducibility and reliability of the Serbian MENQOL. All items had infit and outfit mean squares in the standard accepted range. CONCLUSION: Principal component analysis showed somewhat different constructs from the original scale. However, Rasch analysis confirmed that the MENQOL represents a good metric instrument for menopausal symptoms.

Novel Biomarkers of Heart Failure.

Although substantial improvements have been made in majority of cardiac disorders, heart failure (HF) remains a major health problem, with both increasing incidence and prevalence over the past decades. For that reason, the number of potential biomarkers that could contribute to diagnosis and treatment of HF patients is, almost exponentially, increasing over the recent years. The biomarkers that are, at the moment, more or less ready for use in everyday clinical practice, reflect different pathophysiological processes present in HF. In this review, seven groups of biomarkers associated to myocardial stretch (mid-regional proatrial natriuretic peptide, MR-proANP), myocyte injury (high-sensitive troponins, hs-cTn; heart-type fatty acid-binding protein, H-FABP; glutathione transferase P1, GSTP1), matrix remodeling (galectin-3; soluble isoform of suppression of tumorigenicity 2, sST2), inflammation (growth differentiation factor-15, GDF-15), renal dysfunction (neutrophil gelatinase-associated lipocalin, NGAL; kidney injury molecule-1, KIM-1), neurohumoral activation (adrenomedullin, MR-proADM; copeptin), and oxidative stress (ceruloplasmin; myeloperoxidase, MPO; 8-hydroxy-2'-deoxyguanosine, 8-OHdG; thioredoxin 1, Trx1) in HF will be overviewed. It is important to note that clinical value of individual biomarkers within the single time points in both diagnosis and outcome prediction in HF is limited. Hence, the future of biomarker application in HF lies in the multimarker panel strategy, which would include specific combination of biomarkers that reflect different pathophysiological processes underlying HF.

Lipid peroxidation as risk factor for endothelial dysfunction in antiphospholipid syndrome patients.

The aim of this study was to evaluate oxidative stress markers and it relations to endothelial damage as risk factor for thrombosis in patients with primary (PAPS) and secondary (SAPS) antiphospholipid syndrome (APS) in correlation to traditional risk factors. Flow-mediated (FMD) and nitroglycerine (NMD)-induced dilation of the brachial artery were studied in 140 APS patients (90 PAPS, 50 SAPS) and 40 controls matched by age, sex, and conventional risk factors for atherosclerosis. Markers of oxidative stress, lipid hydroperoxydes (LOOH), advanced oxidation protein products (AOPP), total sulfhydryl groups (tSHG), and paraoxonase 1 activity (PON1) were determined by spectrophotometric method. Oxidative stress dominates in APS patients. LOOH and AOPP correlate to lipid fractions (p < 0.05), unlike PON1, tSHG that correlated to antiphospholipid antibody positivity (p < 0.05). FMD was lower in APS patients comparing to controls (p < 0.001). Cholesterol is independent variable for FMD impairment in control group (p = 0.011); LOOH in PAPS (p = 0.004); LOOH, aCL, and triglycerides in SAPS patients (p = 0.009, p = 0.049, and p = 0.012, respectively). Combined predictive of aCL and LOOH is better for FMD impairment than LOOH alone in both PAPS and SAPS patients (AUC 0.727, p = 0.001, 95 % CI 0.616-0.837 and AUC 0.824, p˂0.001, 95 % CI 0.690-0.957, respectively). Lipid peroxidation is independent predictor for endothelial dysfunction in APS patients. We demonstrated synergistic effect of aCL and LOOH as risk for endothelial impairment in both PAPS and SAPS patients.

Comparison of temporal and stride characteristics in myotonic dystrophies type 1 and 2 during dual-task walking.

OBJECTIVE: We analyzed temporal and stride characteristics in patients with myotonic dystrophy type 1 (DM1) and type 2 (DM2) while performing dual mental and motor tasks, and investigated correlations between gait parameters and cognitive impairments. METHOD: Dual-task walking was performed by 37 patients (20 DM1 and 17 DM2) and 48 healthy subjects divided into two groups, age- and gender-matched control group for DM1 (HC1) and age- and gender-matched control group for DM2 (HC2). The subjects performed a basic walking task, dual-motor task, dual-mental task, and combined motor and mental task. RESULTS: DM1 and DM2 patients differed significantly in temporal and stride characteristics compared to HC. Main differences in DM1 were slower gait and shorter stride length, while both DM1 and DM2 patients had a higher degree of variation of the swing time during dual-task gait, a parameter that reflects posture and balance. Impact of the cognitive dual task on gait pattern changes was also observed. Visuospatial ability correlated with gait changes in DM1, while executive functions had stronger influence in DM2 (p<0.01). Both patient groups had leg muscle weakness. CONCLUSION: Gait pattern was impaired in both patient groups concerning temporal and stride characteristics. Dual-task walking paradigm may discover mild initial gait changes and could provide early identification of fall risks and predict possible falls in DM patients.

Serbian version of the Women's Health Questionnaire: psychometric properties.

OBJECTIVE: The aim of this study was to translate the Women's Health Questionnaire (WHQ) into the Serbian language and assess its validity and reliability in a population of Serbian menopausal women. METHODS: The study included peri- and postmenopausal women from two Community Health Centers in Belgrade. Women filled out the WHQ, the Short Form-36 questionnaire (SF-36) and Beck's Depression Inventory (BDI). The WHQ was translated according to recommended methodology for cultural adaptation of questionnaires and its psychometric characteristics (internal consistency, inter-rater reliability, factor analysis, sensitivity, discriminant, construct and criterion validity) were tested. RESULTS: In the Serbian population, the mean values of the WHQ domains were mostly comparable with reference Mediterranean countries. Whole-scale Cronbach's α was 0.838. Moreover, five WHQ domains had a value of Cronbach's α above the acceptable limit. There were no significant differences in WHQ scores between our two investigators. On exploratory factor analysis, we obtained ten factors (two items formed a new factor - 'Menstrual pathology'). Almost all SF-36 domains were significantly associated with WHQ domains, while the BDI was associated with domains: depressive mood, anxiety and sleep problems. Based on ROC analysis, WHQ is slightly more reliable for perimenopausal than postmenopausal Serbian women. CONCLUSION: The Serbian version of the WHQ showed very good reliability and validity in assessment of quality of life among menopausal women. The WHQ is applicable for both peri- and postmenopausal women.

Does the presence of secondary antiphospholipid syndrome in patients with systemic lupus erythematodes accelerate carotid arteries intima-media thickness changes?

Patients with systemic lupus erythematosus (SLE) have an increased risk of atherosclerosis. The aim of our study was to evaluate the importance of secondary antiphospholipid presence (SAPS) in light of carotid artery intima-media thickness (CIMT) changes in SLE patients. Our study included 120 patients with SLE (46.02 ± 13.16 years), 108 women and 12 men divided into two groups: 58 patients with SAPS and 62 SLE patients without SAPS taken as a control group. All patients underwent assessment of CIMT of right and left common carotid artery (CCA) and left and right internal carotid artery (ICA) by Doppler ultrasonography. In SAPS group, 48.3 % patients had significant changes of carotid arteries comparing to 16.1 % patients in control group (p = 0.008). Average CIMT values in left and right CCA and right ICA were significantly higher in SAPS group. No significant relationship between antiphospholipid antibody type and CIMT changes was established. Multivariate regression analysis revealed SAPS as a significant predictor of CIMT changes in SLE patients (p = 0.025). Presence of SAPS in SLE patients is associated with significant CIMT changes. Additional autoimmune burden leads to a need for a more aggressive education and prevention considering standard risk factors in this group of patients.

A simple method to assess freezing of gait in Parkinson's disease patients

Freezing of gait (FOG) can be assessed by clinical and instrumental methods. Clinical examination has the advantage of being available to most clinicians; however, it requires experience and may not reveal FOG even for cases confirmed by the medical history. Instrumental methods have an advantage in that they may be used for ambulatory monitoring. The aim of the present study was to describe and evaluate a new instrumental method based on a force sensitive resistor and Pearson's correlation coefficient (Pcc) for the assessment of FOG. Nine patients with Parkinson's disease in the "on" state walked through a corridor, passed through a doorway and made a U-turn. We analyzed 24 FOG episodes by computing the Pcc between one "regular/normal" step and the rest of the steps. The Pcc reached ±1 for "normal" locomotion, while correlation diminished due to the lack of periodicity during FOG episodes. Gait was assessed in parallel with video. FOG episodes determined from the video were all detected with the proposed method. The computed duration of the FOG episodes was compared with those estimated from the video. The method was sensitive to various types of freezing; although no differences due to different types of freezing were detected. The study showed that Pcc analysis permitted the computerized detection of FOG in a simple manner analogous to human visual judgment, and its automation may be useful in clinical practice to provide a record of the history of FOG.

A simple method to assess freezing of gait in Parkinson's disease patients.

Freezing of gait (FOG) can be assessed by clinical and instrumental methods. Clinical examination has the advantage of being available to most clinicians; however, it requires experience and may not reveal FOG even for cases confirmed by the medical history. Instrumental methods have an advantage in that they may be used for ambulatory monitoring. The aim of the present study was to describe and evaluate a new instrumental method based on a force sensitive resistor and Pearson's correlation coefficient (Pcc) for the assessment of FOG. Nine patients with Parkinson's disease in the "on" state walked through a corridor, passed through a doorway and made a U-turn. We analyzed 24 FOG episodes by computing the Pcc between one "regular/normal" step and the rest of the steps. The Pcc reached ±1 for "normal" locomotion, while correlation diminished due to the lack of periodicity during FOG episodes. Gait was assessed in parallel with video. FOG episodes determined from the video were all detected with the proposed method. The computed duration of the FOG episodes was compared with those estimated from the video. The method was sensitive to various types of freezing; although no differences due to different types of freezing were detected. The study showed that Pcc analysis permitted the computerized detection of FOG in a simple manner analogous to human visual judgment, and its automation may be useful in clinical practice to provide a record of the history of FOG.

Muscle stretch-induced modulation of noxiously activated dorsal horn neurons of feline spinal cord.

The present work was designed to check for the possibility of interactions between mechanical innocuous and chemically induced noxious muscle afferent inputs on discharge behavior of nociceptive superficial dorsal horn neurons (SDHNs) of the spinal cord in decerebrated cats. The innocuous and noxious stimuli were applied separately and in combination, so that the effects of the innocuous stimulus on nociceptive processing could be evaluated. The innocuous stimulus consisted of ramp-and-hold stretches of the gastrocnemius muscles, whereas the noxious stimulus consisted of i.a. injections of bradykinin (BK; 0.5-1 ml, 50 microg/ml) into the arterial circulation of same muscles. Only neurons up to approximately 1mm depth and those that responded to noxious pinch of the gastrocnemius muscles were selected for further analysis. The activity of 16 dorsal horn neurons was recorded extracellularly with high-impedance glass microelectrodes, out of which seven responded to stretch, while 12 neurons responded to bradykinin injections. The bradykinin injections induced three types of responses: excitatory, inhibitory and mixed. The majority of the neurons that showed excitatory and mixed responses to bradykinin were also influenced by stretches applied directly after the bradykinin injection. In these neurons, the stretch usually counteracted the bradykinin-induced response, i.e. shortening and reducing bradykinin-induced excitation and re-exciting the cells after bradykinin-induced inhibition. The mechanism of the stretch modulation is proposed to reside in a segmental spinal control of the nociceptive transmission.

Fatigue effects in the cat gastrocnemius during frequency-modulated efferent stimulation.

Effects of low- and high-frequency fatigue were studied on muscle dynamics in isometric conditions of the cat gastrocnemius. Fatiguing sessions consisted of 25-28 repetitions of the standard tests that included an 18-s interval of continuous frequency-modulated stimulation preceded and followed by single stimuli evoking twitch contractions. The rate of the continuous part was changed in accordance with a symmetrical double-trapezoidal signal, including three successive phases of constant rate at 10, 40 and 10s(-1); between these phases, each lasting for 4s, the rate changed linearly within a 2-s interval. The following modes of muscle activation were applied: (i) stimulation of single filaments constituting approximately one-fifth to one-seventh of the total cross-section of the L(7) and S(1) ventral roots; (ii) the distributed stimulation of five similar filaments; and (iii) direct stimulation of muscle through bipolar wire electrodes. A relative drop in tension, the fatigue index, expressed as the ratio at the end of a fatigue session over its value at the beginning of the test, was used to quantify fatigue effects. The fatigue indices during low-rate stimulation were 0.56+/-0.03 (mean+/-S.D.) at the first phase and 0. 64+/-0.02 at the third phase, while during high-rate stimulation this parameter was only 0.32+/-0.02. The high-rate stimulation noticeably increased the mean tension during low-rate stimulation; the ratio between the reactions at the third and the first phases could be as much as two to three times greater than that at the beginning of the fatigue session. It was demonstrated that the potentiation was connected with after-effects of the rate-tension hysteresis. The hysteresis decreased with fatigue, the fatigue index for the rate-tension loop areas ranging from 0.39 to 0.52 (0.45+/-0. 05, mean+/-S.D.). The fatigue processes developed more quickly and intensively in the previously fatigued muscles: the obtained fatigue indices were 0.73+/-0.05 and 0.70+/-0.10 at the first and third phases, and 0.62+/-0.06 (mean+/-S.D.) at the second phase of stimulation, respectively. In the cases of distributed and direct stimulation applied to muscles in a fresh state, fatigue dynamics did not differ significantly from those observed during single-filament stimulation. In experiments with distributed stimulation applied to previously fatigued muscles, a powerful depression of the high-rate components was registered in several cases, which seemed to be connected with depressive effects at the level of nerve-muscle synaptic transmission. The effects of low- and high-frequency fatigue were studied in isometric conditions of muscle contraction. In addition to the well-known differentiation between low- and high-frequency fatigue effects, the complex pattern of efferent stimulation used allowed us to identify additional fatigue-related changes in the rate-tension hysteresis. This hysteresis seems to be one of the possible mechanisms directed to compensate for low-frequency fatigue in the muscle contraction.

Fatigue-related changes in electomyogram activity of the cat gastrocnemius during frequency-modulated efferent stimulation.

Changes in the compound muscle action potentials of cat gastrocnemius muscle were studied during low- and high-frequency fatigue. Fatiguing session consisted of 25-28 repetitions of the standard single fatigue tests (1.5min interval between the tests) that included the part of continuous frequency-modulated stimulation preceded and followed by single stimuli evoking twitch contractions in the muscle. The rate of the continuous part was changed in accordance with symmetrical double-trapezoidal signal, including three successive phases of constant rate at 10, 40 and 10s(-1); between these phases of 4s duration the rate changed linearly within a 2s interval. During fatigue relative changes in compound muscle action potential waves were usually smaller than changes in tension. Within the same fatigue procedure applied to a fresh muscle, the drop in tension was as much as 35% for high-rate stimulation and 59-71% for low-rate stimulation, whereas the decrease of the peak-to-peak compound muscle action potential waves amplitudes did not exceed 10-20%. Compound muscle action potential waves underwent the most pronounced depression during high-rate stimulation, the decrease proceeding during the following phase of low-rate stimulation. The tension changes during long-lasting activation were different for low- and high-frequency fatigue, with more pronounced depression during low-rate stimulation. As a rule, compound muscle action potential waves changes followed opposite patterns. Compound muscle action potential waves progressively split up, which was probably associated with a continuous slowing of the action potentials in the most fatigable motor units and the subsequent disappearance of the reactions at least in part of the motor units. Hysteresis effects in muscle contraction seem to be able, at least in part, to compensate for some of the depressive effects appearing during conduction of action potentials in muscle fibres. Changes in the compound muscle action potentials were studied during development of the muscle fatigue. These changes showed pronounced dependency on stimulation rate allowing differentiating effects of low- and high-frequency stimulation of the efferents supplying muscle under study. At the same time the fatigue-related changes in the action potentials were noticeably smaller than changes in tension, thus supporting existing concepts in the field arguing that fatigue effects are mainly connected with corresponding activity-dependent changes in muscle contraction machinery.

Changes in movement final position associated with agonist and antagonist muscle fatigue.

We have tested the hypothesis that agonist and antagonist muscle fatigue could affect the final position of rapid, discrete movements. Six subjects performed consecutive elbow flexion and extension movements between two targets, with their eyes closed prior to, and after fatiguing the elbow extensor muscles. The results demonstrate that elbow extension movements performed in the post-test period systematically undershot the final position as compared to pre-test movements. However, attainment of the aimed final position in elbow flexion movements was unaffected by fatiguing of the extensor muscles. Undershoot of the final position obtained in extension movements was associated with agonist muscle fatigue, a result that was expected from the point of view of current motor control theories, and that could be explained by a reduced ability of the shortening muscle to exert force. On the other hand, the absence of the expected overshoot of the final position when the antagonist is fatigued, indicates the involvement of various reflex and/or central mechanisms operating around the stretched muscle that could contribute to returning the limb to the standard final position after a brief prominent overshoot.

Changes in fusimotor activity during repetitive lengthening muscle contractions in decerebrate cats.

Responses of fusimotor neurons to lengthening vs isometric contractions have been studied in decerebrate cats. Spike discharges of fusimotor neurons to the medial gastrocnemius muscle were recorded from this muscle nerve filament during sequences of contractions and/or stretches of the lateral gastrocnemius and soleus muscles. The sequences lasted for 250-450s (duty cycle 4:2 s). Isometric contractions were elicited by electrical stimulation (40 Hz, 1.3 times motor threshold) of the muscle nerves. Lengthening contractions were elicited in the same way while the muscles were stretched by 4 mm at a velocity of 1 mm/s. Of 25 fusimotor neurons studied, 23 responded to muscle contractions with an increase in firing rate, subsiding towards the end of the sequence. The increase was either modulated with each subsequent contraction or smooth throughout the sequence. Approximately 64% of fusimotor neurons, responding to muscle contractions, responded in a similar way to the sequences of muscle stretches, applied alone. Responses to sequences of the lengthening contractions were significantly larger, on average, than those to the isometric ones, but smaller than the sum of the responses to the contractions and stretches applied separately. On the other hand, they were also larger in fusimotor units, showing no overt responses to muscle stretches alone.

The effects of prior antagonist muscle vibration on performance of rapid movements.

The effects of prior vibration of the antagonist triceps muscle on the performance of rapid discrete elbow flexion movements were studied in healthy volunteers. The subjects performed 520 movements over five experimental sessions. The application of prior vibration resulted in a shift of the initial position, an undershoot of the final position in untrained subjects, and also in trained subjects if not applied during practice. On the contrary, no undershoot occurred in trained subjects when prior vibration was applied during practice. Improvement in movement performance, as judged by a decrease in variability of the final position, was less successful when vibration was applied during practice. It is supposed that the undershoots were due to prior vibration-induced alterations in proprioceptive messages and a consequent erroneous sense of the arm position. These effects seem to be overcome by practice, but also seem to interfere with learning-based movement improvement.

Effects of cutaneous afferent input on fatigue-induced changes in fusimotor activity of decerebrate cats.

Interaction of cutaneous and small-diameter, primarily fatigue-induced, muscle afferent inputs on fusimotor neurons has been studied in decerebrate cats. Spike discharges of fusimotor neurons to medial gastrocnemius were recorded from filaments dissected free from this muscle nerve. Non-noxious mechanical stimuli (10 Hz, 2 mm vibration) were applied to the skin area on the lateral side of the heel, innervated by sural nerve, during long-lasting (250 s) fatiguing contraction of lateral gastrocnemius and soleus muscles, elicited by electrical stimulation (40 Hz, 1.3 x motor threshold) of the muscle nerves. In 15 units (58%) the pattern of responses to muscle contraction and/or fatigue (initial transient, and late long-lasting increase in firing rate, respectively) was preserved in the presence of skin vibration which, by itself, provoked either a slight increase or no changes in fusimotor discharge rate. Pattern of the response to skin vibration prevailed in the presence of muscle contraction and fatigue only if the vibration by itself induced marked increase in fusimotor discharge rate (three units). In the remaining eight units the responses to both stimuli applied simultaneously were dissimilar in pattern to the response to either stimulus applied alone: the initial, tension-related, increase in firing rate was prolonged, while the late, fatigue-induced one was attenuated and its post-contraction part almost abolished. Possible mechanisms and functional role of interaction between cutaneous and muscle afferent inflows are discussed.

A comparison of the effects of agonist and antagonist muscle fatigue on performance of rapid movements.

The aim of this study was to investigate the effects of agonist and antagonist muscle fatigue on the performance of rapid, self-terminating movements. Six subjects performed rapid, consecutive elbow flexion and extension movements between two targets prior to and after fatiguing either the elbow flexor or elbow extensor muscles. The experiments demonstrated consistent results. Agonist muscle fatigue was associated with a decrease in peak velocity and peak deceleration, while a decrease in peak acceleration was particularly prominent. Antagonist muscle fatigue, however, was associated with a decrease in peak deceleration, while a decrease in both the peak velocity and peak acceleration was modest and, in some tests, non-significant. The relative acceleration time (i.e. acceleration time as a proportion of the total movement time) increased when agonists were fatigued, but decreased when antagonists were fatigued. Taken together, these results emphasize the mechanical roles of the agonist and antagonist muscles; namely, the fatigue of each muscle group particularly affected the movement phase in which that group accelerated a limb, while changes of the movement kinematics pattern provided more time for action of the fatigued muscles. In addition, the results presented suggest that agonist muscle fatigue affects movement velocity more than antagonist muscle fatigue, even in movements that demonstrate prominently both mechanical and myoelectric activity of the antagonist muscles, such as rapid, self-terminating movements.

Central changes in muscle fatigue during sustained submaximal isometric voluntary contraction as revealed by transcranial magnetic stimulation.

Changes in responses to transcranial magnetic stimulation (TMS) during submaximal isometric voluntary contraction (60% of maximal voluntary contraction (MVC) of the adductor pollicis muscle and the subsequent recovery period have been studied in healthy volunteers. TMS at twice the motor threshold was applied during the sustained contraction, as well as at rest and during short-lasting (2 s) 60% MVCs before and immediately after the sustained contraction, and at 5 min intervals during the recovery period. Both motor evoked potential (MEP) magnitude (peak and area) and silent period (SP) duration in electromyographic activity (EMG) of the adductor pollicis muscle showed a gradual decrease up to the endurance point and an increase thereafter. MEPs elicited at rest immediately after the fatiguing contraction were larger, whereas those elicited later on during the recovery period did not differ significantly from the controls. It is suggested that the changes in responses to TMS, divergent from those in ongoing voluntary EMG during the sustained 60% MVC, indicate complex processes at levels preceding the motor cortex output cells in an attempt to maintain a submaximal contraction of the fatigued muscle. The increase in MEP magnitude after the sustained 60% MVC may indicate residual changes in cortical activity after fatiguing contraction.

Fusimotor outflow to pretibial flexors during fatiguing contractions of the triceps surae in decerebrate cats.

Changes in discharge rate of fusimotor neurones to pretibial flexor muscles were recorded during and after long-lasting fatiguing isometric and/or isotonic contractions of triceps surae in decerebrate cats. The contractions were elicited by electrical stimulation of the nerves to triceps. Fusimotor spikes were recorded from nerve filaments dissected free from the peroneal nerve. Responses of the fusimotor neurones were diverse. In isometric regime, 22 out of 40 units recorded exhibited an initial increase at the onset of muscle contraction, different in amplitude and duration among the units. In seven of these units an additional brisk burst of spike discharges, of different duration, occurred at the end of the contraction. In 15 fusimotor neurones (14 units with the initial response and an additional unit without it) a slow increase in discharge rate developed, starting during the contraction and outlasting it. In another eleven units the initial response was a decrease in discharge rate, lasting in six of them throughout the contraction. Another six units exhibited a sustained increase in discharge rate throughout the contraction, as well as, at a lower level, but still above the spontaneous one, thereafter. Similar patterns of changes in discharge rate, recorded in 31 of the units, were encountered during isotonic triceps contractions. It should be mentioned that many (about 20) additional silent neurones, responding to manipulating the skin and paw and/or stroking the fur, but not to triceps contractions were encountered. The majority of changes in discharge rate of fusimotor neurones to pretibial flexors differed markedly from those found previously in fusimotor neurones to triceps and hamstring muscles.(ABSTRACT TRUNCATED AT 250 WORDS)

[Smoking and doctors]. / Pusenje duvana i lekari.

The smoking control greatly depends on the general public opinion against smoking. It depends on many factors including the important role of health workers, especially of physicians. The authors interviewed 229 doctors working in the Belgrade University Clinical Centre. They had to answer a WHO questionnaire. The results were as follows: 34% of smokers, 18% of ex-smokers (no significant difference between sexes), and 48% of non-smokers. In the group of smokers 46% tried to strop smoking, but unsuccessfully. In a 5-year period 9% will continue to smoke; 24% will stop smoking, and 66% intend to stop smoking. The reason for those who will stop smoking are their children to whom they wish to give a good example (77%). In the group of non-smokers the reason was their own health. However, the experience of physicians is a good example for their patients (79% of non-smokers and 59% of smokers). For prohibition of tobacco advertising are 78% of non-smokers and 64% of smokers. About 40% of smokers and 25% of non-smokers plead for the permanent raising of tobacco price as a decreasing factor in tobacco consumption. However, all agree with the need of placing a ban on tobacco sales to children. In conclusion, doctors should be at the head of the smoking control and fight against smoking.