Factors affecting postural stability of healthy young adults

The objective of this paper was to examine the relationship between body balancing functions and body characteristics, motor abilities and reaction time. Subjects were 33 university students and 11 professional basketball players sorted into four groups of athletic and non-athletic women and men. Each group consisted of eleven subjects. The body height, weight was measured and the body mass index (BMI) calculated. A bioelectrical device computed the body fat (%). Static and dynamic motor tests, as well as static and dynamic balance tests were used. The reaction time (RT) to sound and light stimuli was measured. The regression analysis of the data revealed significant linear relationship between the amplitude of body sways (BS) and BMI in all groups. Also high correlation was found between back muscle strength and BS in all groups except the non-athletic women. Negative correlation was found between endurance capacity and BS in basketball players, i.e. at higher endurance capacity smaller amplitude BS occurred (r = -0.620, p < 0.04). The RT values showed significant correlations with BS only in the basketball players (r = 0.620, p < 0.04). It is concluded that increase in BMI, back muscle strength and endurance capacity is associated with better postural stability. Some motor abilities (hip flexibility, vertical jumping) show no significant correlations with body balancing, while other motor performances (static hanging) and RT values correlate well with BS only in the well-trained elite basketball players.     

Postpartal ovarian activity of healthy cows and those affected by subclinical metabolic disorders

The postpartal ovarian activity was studied in healthy cows and in those affected by subclinical fatty liver disease and subclinical primary ketosis. Twenty-six dairy cows, 4–7 years old, with not less than 5000 l milk yield in the preceding lactation, were monitored for the following blood parameters: aspartate-amino-transferase (AST)/glutamicoxalacetic transaminase (GOT), albumin, total protein, total lipid, cholesterol, non-esterified fatty acid (NEFA) and triglyceride levels, glucose and ketones. The ratios albumin : total protein and NEFA : triglyceride were also calculated. Blood samples were collected once a week between days 255 and 260 of gestation and days 1–15 postpartum, and subsequently on the 30th, 45th and 60th days postpartum. Based on the biochemical parameters, the cows were assigned in retrospect to three groups: (1) healthy (n = 5), (2) subclinical fatty liver disease (n = 6), and (3) subclinical primary ketosis (n = 10). The postpartal ovarian activity was assessed by rectal palpation and by milk progesterone levels, determined by radioimmunoassay in samples collected 2–3 times weekly between days 5 and 70 postpartum.As early as 10–18 days postpartum, ovarian activity was evident in healthy cows. This was confirmed by the progesterone profiles indicating three regular ovarian cycles with normal hormone levels within 70 days postpartum. All five healthy cows were detected in estrus and only one failed to conceive after insemination.The six cows with subclinical fatty liver disease had no regular cycles and only a few small follicles were palpable on their ovaries. The milk progesterone fluctuated around the basal level (? 1.6 nmol/l). The first Graafian follicles appeared as late as days 30–35 postpartum and the luteal function commenced only between days 38 and 60, as indicated by palpation of corpora lutea and a concomitant rise in milk progesterone. The progesterone peaks were at the lower physiological limits characteristic of luteal function.The ovarian activity of the ten cows with subclinical primary ketosis was intermediate between that of healthy and fatty liver cows. The first follicles and corpora lutea were somewhat delayed, and the progesterone levels fluctuated considerably during the luteal phase. One cow in this group resumed ovarian inactivity during the 70-day postpartal observation period.     

Immunological parameters of 10- to 14-year-old healthy schoolchildren differing in the activity of the emotional motivational behavior systems

The relationship between typological personality features and immune parameters was studied for the first time in healthy schoolchildren. The behavioral diversity was structured on the basis of Gray’s personality theory to evaluate in each child the activity of neurophysiological systems responsible for behavior regulation. A correlation was found between the number and functional properties of peripheral blood mononuclear cells and the systems of behavioral inhibition and activation separately, which makes it possible to differentiate the roles of these two systems in neuroimmune interactions.     

Characteristics of EEG reactivity changes during the performance of dual tasks in healthy subjects (voluntary postural control and calculation)

Comprehensive EEG and stabilography investigation with separate and simultaneous performance of motor (voluntary postural control) and cognitive (calculation) tasks has been performed in 20 healthy subjects (22 ± 0.7 years). Specific spatial and frequency reactive changes have been found during motor task performance. These included an increase in coherence in the EEG α band for distant derivation pairs in the right hemisphere, as well as in symmetric parietal-occipital areas in both hemispheres. Cognitive task performance was accompanied by an increase in coherence for the slow bands (δ and θ) with a higher activation in the left hemisphere and frontal cortex areas. In performing the dual task, one could observe activation of spatial and frequency changes including both motor and cognitive tasks. In the dual tasks where both components were performed worse as compared to the control, reactive reorganization of EEG coherence was less pronounced than during the performance of separate tasks. A decrease in the coherence of the α₁ band in the frontal areas appeared as a zone of “conflict of interest” or interference. In dual tasks with better performance of each component as compared to the control, EEG coherence increased in each specific area, as well as in the areas of “conflict of interests.”     

Pineal gland hormone and idiopathic scoliosis: possible effect of melatonin on sleep-related postural mechanisms

Experimental and clinical evidences indicate that endocrine mechanisms, particularly involving the pineal gland, exert a role in the development of postural deficits leading to the occurrence of idiopatic scoliosis (IS). In particular, experiments performed in bipedal animals have shown that removal of the pineal gland, which secretes melatonin (M), induced a scoliosis, and that in such preparations, administration of this hormone prevented the development of this deformity (cf. 131). It appears also that adolescents with IS showed a reduced level of serum M with respect to age-related control subjects. The possible mechanisms involved in the M regulation of the tonic contraction of the axial musculature have been discussed. It is known that the pineal gland is implicated in the control of circadian rhythms, including the sleep-waking cycle, and that during this cycle there are prominent changes in postural activity, which affect not only the limbs, but also the axial musculature. These changes are characterized by a decrease followed by a suppression of postural activity, which occur particularly during transition from wakefulness to synchronized sleep and, more prominently, to rapid eye movement (REM) sleep. Episodes of postural atonia may also occur during the cataplectic episodes, which are typical of narcolepsy. Cholinergic and/or cholinoceptive neurons located in the dorsal pontine reticular formation (pRF) and the related medullary inhibitory reticulospinal (RS) system, intervene in the suppression of posture during REM sleep, as well as during the cataplectic episodes which occur in narcolepsy. These structures are under the modulatory (inhibitory) influence of the dorsomedial and the dorsolateral pontine tegmentum, where serotoninergic raphe nuclei (RN) neurons and noradrenergic locus coeruleus (LC) neurons are located. We postulated that M may act not only on the circadian pacemaker, but also directly on the pontine tegmental structures involved in the regulation of posture during the animal states indicated above. This hypothesis is supported by the facts that: 1) the dorsal pRF may contain specific binding sites for M; 2) this structure is particularly sensitive to M in adolescents, as well as in adult subjects affected by narcoleptic disturbances leading to cataplexy; 3) M increases the release of serotonin (5-HT), a neurotransmitter which enhances the postural tone by acting on the dorsal pRF: on the other hand, deficits in M levels may lower the activity of the serotoninergic raphe system, thus leading to a decrease or suppression of postural activity similar to that occurring either during REM sleep or during the cataplectic episodes typical of narcoleptic patients; 4) IS patients may show episodes of sleep apnea, a phenomenon which has been attibuted to a reduced tonic contraction of primary and accessory respiratory muscles during REM, resulting from a reduced release of 5-HT at dorsal pontine level. It has been postulated that, if the reduced M and 5-HT levels are subliminal to produce a complete suppression of posture under the conditions reported above, the reduced postural tone, which results from this condition may lead to the development of IS, due to hypotonia which affects the axial musculature. M secretion could be regulated not only by the activity of the serotoninergic raphe neurons projecting to the pineal gland, but probably also by the activity of noradrenergic LC neurons. It is likely that the development of IS, which results from a reduced level of M and 5-HT, may occur provided that the noradrenergic LC inhibition of the pontine structures is impaired. Such impairment could depend upon genetic factors, similar to those postulated to play a role in narcolepsy. In conclusion, the possibility exists that an impaired activity of brain monoaminergic systems may lead to disfunction in the production of M, which is apparently an important factor in the etiopathogenesis of IS.     

Characteristics of dynamic postural reactions in the locust hindleg

Summary The use of the locust (Schistocerca americana) hindleg in postural control was examined in animals that stood on a repeatedly swayed vertical substrate. Myograms were recorded from leg muscles and the angle of the femoro-tibial joint was monitored photographically. Two discrete strategies were observed,; in compensatory reactions the hindleg was held in place, while in flexion reactions, the leg was moved, most often to complete flexion of the femoro-tibial joint. Tightly coupled, rhythmic bursting occurred in the flexor and levator muscles of the leg during compensatory reactions. Bursting was initiated repeatedly when the substrate was being pulled away from the animal. Bursting was correlated with subsequent decreases in the rate of change of the femorotibial joint angle. Compensatory and flexion reactions occurred preferentially in different ranges of joint angles: most often, compensatory reactions occurred in the midrange, while flexion reactions were elicited in the extremes of joint angle. These differences may be due to the mechanical advantages of the tibial muscles and the leg may be moved to full flexion because of a locking mechanism of the flexor muscle tendon. These reactions are compared with known reflexes of hindleg proprioceptors and contrasted with similar responses of vertebrates.     

A Dutch guideline for the treatment of scoliosis in neuromuscular disorders

Background

Children with neuromuscular disorders with a progressive muscle weakness such as Duchenne Muscular Dystrophy and Spinal Muscular Atrophy frequently develop a progressive scoliosis. A severe scoliosis compromises respiratory function and makes sitting more difficult. Spinal surgery is considered the primary treatment option for correcting severe scoliosis in neuromuscular disorders. Surgery in this population requires a multidisciplinary approach, careful planning, dedicated surgical procedures, and specialized after care.

Methods

The guideline is based on scientific evidence and expert opinions. A multidisciplinary working group representing experts from all relevant specialties performed the research. A literature search was conducted to collect scientific evidence in answer to specific questions posed by the working group. Literature was classified according to the level of evidence.

Results

For most aspects of the treatment scientific evidence is scarce and only low level cohort studies were found. Nevertheless, a high degree of consensus was reached about the management of patients with scoliosis in neuromuscular disorders. This was translated into a set of recommendations, which are now officially accepted as a general guideline in the Netherlands.

Conclusion

In order to optimize the treatment for scoliosis in neuromuscular disorders a Dutch guideline has been composed. This evidence-based, multidisciplinary guideline addresses conservative treatment, the preoperative, perioperative, and postoperative care of scoliosis in neuromuscular disorders.     

Inspiratory muscular activation during threshold therapy in elderly healthy and patients with COPD

Inspiratory muscles training in COPD is controversial not only in relation to the load level required to produce muscular conditioning effects but also in relation to the group of patients benefiting from the training. Consequently, inspiratory muscular response assessment during Threshold^® therapy may help optimizing training strategy. The objective of this study was to evaluate the participation of the diaphragm and the sternocleidomastoid (SMM) muscle to overcome with a 30% Threshold^® load using surface electromyography (sEMG) and to analyze the correlation between SMM activation, maximum strength level of inspiratory muscles (MIP) and obstruction degree in COPD patients (FEV₁). We studied seven healthy elderly subjects, mean age of 68 ± 4 years and seven COPD patients, FEV₁ 45 ± 17% of the predicted value, with mean age 66 ± 8 years. sEMG analysis of SMM muscles and diaphragm were obtained through RMS (root-mean-square) during three stages: pre-loading, loading and post-loading.

Results

In the COPD group, the RMS of the SMM increased 28% during load (p < 0.05) while the RMS of the diaphragm remained constant. In the elderly there was a trend of a 11% increase in diaphragm activity and of 7% in SMM activity but, without reaching significance levels. SMM activity demonstrated good correlation with the obstruction level (r = −0.537).

Conclusion

To overcome the load required by Threshold^® therapy, COPD patients demonstrated an increase of accessory muscles activity, represented by SMM. For the same relative load this increase seems to be proportional to the degree of pulmonary obstruction.     

Cross-connections coordinate postural motoneuron activity in the crayfish abdomen

Intracellular recordings and dye injections were used to examine mutual coupling among slow abdominal postural motoneurons in the 4th abdominal ganglion in crayfish (Procambarus clarkii). Intracellular current injection into one motoneuron altered the spike firing rate of some of its synergists. Depending on the polarity of the injected current, the premotor effect on the synergists was excitatory or inhibitory. The magnitude of the effect was intensity dependent. No dye coupling was found among the motoneurons following injection of Lucifer yellow. The morphological basis of the coupling was examined by differential filling of motoneuron pairs, one with horseradish peroxidase and the other with Lucifer yellow. The stained motoneurons were simultaneously visualized under light microscopy to determine the proximity of their differently colored dendrites. It was thus possible to locate the site of the presumed monosynaptic contacts between them. Combined physiological and morphological evidence suggests that these neurons are mutually coupled, forming part of an integrative system for abdominal posture control in crayfish.     

The effect of leg preference on postural stability in healthy athletes

In research regarding postural stability, leg preference is often tested and controlled for. However, leg preference may vary between tasks. As athletes are a group of interest for postural stability testing, we evaluated the effect of five leg preference tasks categorization (step up, hop, ball kick, balance, pick up) on single-leg postural stability of 16 field hockey athletes. The ‘center of pressure speed’ was calculated as the primary outcome variable of single-leg postural stability. Secondary variables were ‘mean length of the GRF vector in the horizontal plane’, ‘mean length of the ankle angular velocity vector’, and ‘mean length of the hip angular velocity vector’, as well as the separate outcomes per degree of freedom. Results showed that leg preference was inconsistent between leg preference tasks. Moreover, the primary and secondary variables yielded no significant difference between the preferred and non-preferred legs, regardless of the applied leg preference task categorization (p>0.05). The present findings do not support the usability of leg preference tasks in controlling for bias of postural stability. In conclusion, none of the applied leg preference tasks revealed a significant effect on postural stability in healthy field hockey athletes.     

Lipid fluidity and composition of the erythrocyte membrane from healthy dogs and labrador retrievers with hereditary muscular dystrophy

Erythrocyte membranes and their liposomes were prepared from clinically normal dogs and Labrador retrievers with hereditary muscular dystrophy. The static and dynamic components of fluidity of each membrane were then assessed by steady-state fluorescence polarization techniques using limiting hindered fluorescence anisotropy and order parameter values of 1,6-diphenyl-1,3,5-hexatriene (DPH) and fluorescence anisotropy values ofdl-2-(9-anthroyl)-stearic acid anddl-12-(9-anthroyl)-stearic acid, respectively. Membrane lipids were extracted and analyzed by thin-layer chromatography and gas chromatography. The results of these studies demonstrated that the lipid fluidity of erythrocyte membranes, and their liposomes, prepared from dystrophic dogs were found to possess significantly lower static and dynamic components of fluidity than control counterparts. Analysis of the composition of membranes from dystrophic dogs revealed a higher ratio of saturated fatty acyl chain/unsaturated chains (w/w) and lower double-bond index. Alterations in the fatty acid composition such as decrease in levels of linoleic (18:2) and arachidonic (20:4) acids and increase in palmitic (16:0) and stearic (18:0) acids were also observed in the membranes of dystrophic animals. These associated fatty acyl alterations could explain, at least in part, the differences in membrane fluidity between dystrophic and control dogs.