Measuring range of active cervical rotation in a position of full head flexion using the 3D Fastrak measurement system: an intra-tester reliability study

Most external assessments of cervical range of motion assess the upper and lower cervical regions simultaneously. This study investigated the within and between days reliability of the clinical method used to bias this movement to the upper cervical region, namely measuring rotation of the head and neck in a position of full cervical flexion. Measurements were made using the Fastrak measurement system and were conducted by one operator. Results indicated high levels of within and between days repeatability (range of ICC2,1 values: 0.85-0.95). The ranges of axial rotation to right and left, measured with the neck positioned in full flexion, were approximately 56% and 50%, respectively of total cervical rotation, which relates well to the proportional division of rotation in the upper and lower cervical regions. These results suggest that this method of measuring rotation would be appropriate for use in subject studies where movement dysfunction is present in the upper cervical region, such as those with cervicogenic headache. (C) 2003 Elsevier Science Ltd. All rights reserved.

An electromyographic analysis of the deep cervical flexor muscles in performance of craniocervical flexion

Background and Purpose. This study evaluated an electromyographic technique for the measurement of muscle activity of the deep cervical flexor (DCF) muscles. Electromyographic signals were detected from the DCF, sternocleidomastoid (SCM), and anterior scalene (AS) muscles during performance of the craniocervical flexion (CCF) test, which involves performing 5 stages of increasing craniocervical flexion range of motion-the anatomical action of the DCF muscles. Subjects. Ten volunteers without known pathology or impairment participated in this study. Methods. Root-mean-square (RMS) values were calculated for the DCF, SCM, and AS muscles during performance of the CCF test. Myoelectric signals were recorded from the DCF muscles using bipolar electrodes placed over the posterior oropharyngeal wall. Reliability estimates of normalized RMS values were obtained by evaluating intraclass correlation coefficients and the normalized standard error of the mean (SEM). Results. A linear relationship was evident between the amplitude of DCF muscle activity and the incremental stages of the CCF test (F=239.04, df=36, P<.0001). Normalized SEMs in the range 6.7% to 10.3% were obtained for the normalized RMS values for the DCF muscles, providing evidence of reliability for these variables. Discussion and Conclusion. This approach for obtaining a direct measure of the DCF muscles, which differs from those previously used, may be useful for the examination of these muscles in future electromyographic applications.

Myoelectric manifestations of sternocleidomastoid and anterior scalene muscle fatigue in chronic neck pain patients

Objective: This study compares myoelectric manifestations of fatigue of the sternocleidomastoid (SCM) and anterior scalene (AS) muscles between 10 chronic neck pain subjects and 10 normal matched controls. Methods: Surface electromyography (sEMG) signals were recorded from the sternal bead of SCM and AS muscles bilaterally during submaximal isometric cervical flexion contractions at 25 and 50% of the maximum voluntary contraction (MVC). The mean frequency, average rectified value and conduction velocity of the sEMG signal were calculated to quantify myoelectric manifestations of muscle fatigue. Results: For both the SCM and AS muscles, the Mann-Whitney U test indicated that the initial value and slope of the mean frequency in neck pain patients were greater than in healthy subjects (P < 0.05). This was significant both at 25 and 50% of MVC. Conclusions: These results suggest: (a) a predominance of type-II fibres in the neck pain patients and/or (b) greater fatigability of the superficial cervical flexors in neck pain patients. These results are in agreement with previous muscle biopsy studies in subjects with neck pain, which identified transformation of slow-twitch type-I fibres to fast-twitch type-IIB fibres, as well as the clinical observation of reduced endurance in the cervical flexors in neck pain patients. (C) 2003 Elsevier Science Ireland Ltd. All rights reserved.

A molecular mechanism for mRNA trafficking in neuronal dendrites

Specific neuronal mRNAs are localized in dendrites, often concentrated in dendritic spines and spine synapses, where they are translated. The molecular mechanism of localization is mostly unknown. Here we have explored the roles of A2 response element (A2RE), a cis-acting signal for oligodendrocyte RNA trafficking, and its cognate trans-acting factor, heterogeneous nuclear ribonucleoprotein ( hnRNP) A2, in neurons. Fluorescently labeled chimeric RNAs containing A2RE were microinjected into hippocampal neurons, and RNA transport followed using confocal laser scanning microscopy. These RNA molecules, but not RNA lacking the A2RE sequence, were transported in granules to the distal neurites. hnRNP A2 protein was implicated as the cognate trans-acting factor: it was colocalized with RNA in cytoplasmic granules, and RNA trafficking in neurites was compromised by A2RE mutations that abrogate hnRNP A2 binding. Coinjection of antibodies to hnRNP A2 halved the number of trafficking cells, and treatment of neurons with antisense oligonucleotides also disrupted A2RE - RNA transport. Colchicine inhibited trafficking, whereas cells treated with cytochalasin were unaffected, implicating involvement of microtubules rather than microfilaments. A2RE-like sequences are found in a subset of dendritically localized mRNAs, which, together with these results, suggests that a molecular mechanism based on this cis-acting sequence may contribute to dendritic RNA localization.

Spinal stiffness changes throughout the respiratory cycle

Posteroanterior stiffness of the lumbar spine is influenced by factors, including trunk muscle activity and intra-abdominal pressure (IAP). Because these factors vary with breathing, this study investigated whether stiffness is modulated in a cyclical manner with respiration. A further aim was to investigate the relationship between stiffness and IAP or abdominal and paraspinal muscle activity. Stiffness was measured from force-displacement responses of a posteroanterior force applied over the spinous process of L-2 and L-4. Recordings were made of IAP and electromyographic activity from L-4/L-2 erector spinae, abdominal muscles, and chest wall. Stiffness was measured with the lung volume held at the extremes of tidal volume and at greater and lesser volumes. Stiffness at L-4 and L-2 increased above base-level values at functional residual capacity (L-2 14.9 N/mm and L-4 15.3 N/mm) with both inspiratory and expiratory efforts. The increase was related to the respiratory effort and was greatest during maximum expiration (L-2 24.9 N/mm and L-4 23.9 N/mm). The results indicate that changes in trunk muscle activity and IAP with respiratory efforts modulate spinal stiffness. In addition, the diaphragm may augment spinal stiffness via attachment of its crural fibers to the lumbar vertebrae.

Impaired postural compensation for respiration in people with recurrent low back pain

This study evaluated the degree to which the disturbance to posture from respiration is compensated for in healthy normals and whether this is different in people with recurrent low back pain (LBP), and to compare the changes when respiratory demand is increased. Angular displacement of the lumbar spine and hips, and motion of the centre of pressure (COP), were recorded with high resolution and respiratory phase was recorded from ribcage motion. With subjects standing in a relaxed posture, recordings were made during quiet breathing, while breathing with increased dead-space to induce hypercapnoea, and while subjects voluntarily increased their respiration to match ribcage expansion that was induced in the hypercapnoea condition. The relationship between respiration and the movement parameters was measured from the coherence between breathing and COP and angular motion at the frequency of respiration, and from averages triggered from the respiratory data. Small angular changes in the lumbopelvic and hip angles were evident at the frequency of respiration in both groups. However, in quiet standing, the LBP subjects had a greater displacement of their COP that was associated with respiration than the control subjects. The LBP group had a trend for less hip motion. There were no changes in the movement parameters when respiratory demand increased involuntarily via hypercapnoea, but when respiration increased voluntarily, the amplitude of motion and the displacement of the COP increased in both groups. The present data suggest that the postural compensation to respiration counteracts at least part of the disturbance to posture caused by respiration and that this compensation may be less effective in people with LBP.

The ultrastructure and function of the silk-producing basitarsus in the Hilarini (Diptera : Ernpididae)

The tribe Hilarini (Diptera: Empididae), commonly known as dance flies, can be recognised by their swollen silk-producing prothoracic basitarsus, a male secondary sexual characteristic. The ultrastructure and function of the silk-producing basitarsus from one undescribed morphospecies of Hilarini, 'Hilarempis 20', is presented. Male H. 20 collect small parcels of diatomaceous algae from the surface of freshwater creeks that they bind with silk produced by the gland in the basitarsus. The gift is then presented to females in a nearby swarm, composed predominately of females. The basitarsus houses approximately 12 pairs of class III dermal glandular units that congregate on the ventral side of the cavity. Each gland cell has a large extracellular lumen where secretion accumulates. The lumen drains to the outside via a conducting canal encompassed by a canal cell and a duct extending through the shaft of a specialised secretory spine. The secretory spines lie in pairs in a ventral groove that runs the length of the basitarsus. A comparison of the basitarsal secretory spines with sensilla on the basitarsi of non gland-bearing legs of males, and with non gland-bearing prothoracic. basitarsi of females, suggests that the glandular units are derived from contact chemosensory sensilla. (C) 2003 Elsevier Ltd. All rights reserved.

A longitudinal analysis of sex differences in bone mineral accrual in healthy 8-19-year-old boys and girls

Background: Although early in life there is little discernible difference in bone mass between boys and girls, at puberty sex differences are observed. It is uncertain if these differences represent differences in bone mass or just differences in anthropometric dimensions. Aim: The study aimed to identify whether sex independently affects bone mineral content (BMC) accrual in growing boys and girls. Three sites are investigated: total body (TB), femoral neck (FN) and lumbar spine (LS). Subjects and methods: 85 boys and 67 girls were assessed annually for seven consecutive years. BMC was assessed by dual energy X-ray absorptiometry (DXA). Biological age was defined as years from age at peak height velocity (PHV). Data were analysed using a hierarchical (random effects) modelling approach. Results: When biological age, body size and body composition were controlled, boys had statistically significantly higher TB and FN BMC at all maturity levels (p < 0.05). No independent sex differences were found at the LS (p > 0.05). Conclusion: Although a statistical significant sex effect is observed, it is less than the error of the measurement, and thus sex difference are debatable. In general, sex difference are explained by anthropometric difference

Effect of fatigue on torque output and electromyographic measures of trunk muscles during isometric axial rotation

Objectives: To examine the changes in torque output resulting from fatigue, as well as changes in electromyographic measures of trunk muscles during isometric axial rotation and to compare these changes between directions of axial rotation. Design: Subjects performed fatiguing right and left isometric axial rotation of the trunk at 80% of maximum voluntary contraction while standing upright. Setting: A rehabilitation center. Participants: Twenty-three men with no history of back pain. Interventions: Not applicable. Main Outcome Measures: Surface electromyographic Signals were recorded from 6 trunk muscles bilaterally. The primary torque in the transverse plane and the coupling torques in sagittal and coronal planes were also measured. Results: During the fatiguing axial rotation contraction, coupling torques of both sagittal and coronal planes were slightly decreased and no difference was found between directions of axial rotation. Decreasing median frequency and an increase in electromyographic amplitude were also found in trunk muscles with different degrees of changes in individual muscles. There were significant differences (P

Reliability of electromyographic and torque measures during isometric axial rotation exertions of the trunk

Objective: The aim of the present study was to investigate the between-days reliability of electromyographic (EMG) measurement of 6 bilateral trunk muscles and also the torque output in 3 planes during isometric right and left axial rotation at different exertion levels. Methods: Ten healthy subjects performed isometric right and left axial rotation at 100, 70, 50 and 30% maximum voluntary contractions in two testing sessions at least 7 days apart. EMG amplitude and frequency analyses of the recorded surface EMG signals were performed for rectus abdominis, external oblique, internal oblique, latissimus dorsi, iliocostalis lumborum and multifidus bilaterally. The primary torque in the transverse plane and the coupling torques in sagittal and coronal planes were measured. Results: For both EMG amplitude and frequency values, good (intraclass correlation coefficient, ICC = 0.75-0.89) to excellent (ICC greater than or equal to 0.90) reliability was found in the 6 trunk muscles at different exertion levels during axial rotation. The reliability of both maximal isometric axial rotation torque and coupling torques in sagittal and coronal planes were found to be excellent (ICC greater than or equal to 0.93). Conclusions: Good to excellent reliability of EMG measures of trunk muscles and torque measurements during isometric axial rotation was demonstrated. This provides further confidence of using EMG and triaxial torque assessment as outcome measures in rehabilitation and in the evaluation of the human performance in the work place. (C) 2003 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Abnormalities of the PTH-vitamin D axis and bone turnover markers in children, adolescents and adults with cystic fibrosis: comparison with healthy controls

Abnormalities of calcium and vitamin D metabolism in cystic fibrosis (CF) are well documented. We tested the hypothesis that alterations in calcium metabolism are related to vitamin D deficiency, and that bone resorption is increased relative to accretion in patients with CF. Calcitropic hormones, electrolytes, osteocalcin (OC) and bone alkaline phosphatase (BAP), (markers of bone mineralisation), urinary deoxypyridinoline [total (t) Dpd, a marker of bone resorption] and lumbar spine bone mineral density (LS BMD), expressed as a z-score, were measured in 149 (81 M) CF and 141 (61 M) control children aged 5.3-10.99 years, adolescents aged 11-17.99 years and adults aged 18-55.9 years. Data were analysed by multiple regression to adjust for age. In patients, FEV1% predicted and CRP (as disease severity markers), genotype and pancreatic status (PS) were recorded. The distribution of PTH differed between groups (P

Gender differences in CF phenotype associated with low bone mineral density

Adolescents and adults with CF have lower bone mineral density (BMD) than normal, but its relationship with phenotype is not well understood. Point FEV1% predicted (FEV) and rate of change of FEV are biased estimates of disease severity, because progressively older subjects represent a selected survivor population, with females at greater risk of death than males. To investigate the relationship between BMD and phenotype we used an index (predicted age at death) derived from Bayesian estimates of slope and intercept of FEV, age at last measurement and survival status. Predictive equations for the index were derived from 97 subjects (78 survivors) from the RCH CF clinic, and applied to a group of 102 comparable subjects who had BMD measured, classified as having‘mild’ ()75th), ‘moderate’ (25– 75th), or ‘severe’ (-25th centile) phenotype. Total body (TB) and lumbar spine (LS) BMD z-scores (Z) were compared, adjustingfor gender effects, using 2-way ANOVA. Annual mean change in FEV segregated, as expected, according to phenotype, ‘severe’ (ns25), ‘moderate’ (ns51) and ‘mild’ (ns25) y3.01(y3.73 to y2.30)%, y0.85(y1.36 to y0.35)%, 2.70(1.92 to 3.46)%, respectively, with no gender difference. LS and TB BMDZ were different in each phenotype (P-s 0.002), LS BMDZ for ‘severe’, ‘moderate’ and ‘mild’ y1.63(CI: y2.07 to y 1.19), y0.86(CI: y1.17 to y0.55), y0.06(CI: y0.54 to 0.41). Males had lower LS BMDZ than females overall (y1.22 (CI: y1.54 to y0.91) vs. y0.48(CI: y 0.84 to y0.12) Ps0.002). In the ‘severe’ group, males had lower TB BMDZ and LS BMDZ (PF0.002). Low BMD is associated with ‘moderate’ and ‘severe’ phenotypes, with relative preservation in females in the ‘severe’ group. Female biology (reproductive fitness) might promote resistance to bone resorption at a critical level of BMD loss.

Alterations of neocortical pyramidal cell phenotype in the Ts65Dn mouse model of Down syndrome: Effects of environmental enrichment

Mental retardation in individuals with Down syndrome (DS) is thought to result from anomalous development and function of the brain; however, the underlying neuropathological processes have yet to be determined. Early implementation of special care programs result in limited, and temporary, cognitive improvements in DS individuals. In the present study, we investigated the possible neural correlates of these limited improvements. More specifically, we studied cortical pyramidal cells in the frontal cortex of Ts65Dn mice, a partial trisomy of murine chromosome 16 (MMU16) model characterized by cognitive deficits, hyperactivity, behavioral disruption and reduced attention levels similar to those observed in DS, and their control littermates. Animals were raised either in a standard or in an enriched environment. Environmental enrichment had a marked effect on pyramidal cell structure in control animals. Pyramidal cells in environmentally enriched control animals were significantly more branched and more spinous than non-enriched controls. However, environmental enrichment had little effect on pyramidal cell structure in Ts65Dn mice. As each dendritic spine receives at least one excitatory input, differences in the number of spines found in the dendritic arbors of pyramidal cells in the two groups reflect differences in the number of excitatory inputs they receive and, consequently, complexity in cortical circuitry. The present results suggest that behavioral deficits demonstrated in the Ts65Dn model could be attributed to abnormal circuit development.

The pyramidal neuron in occipital, temporal and prefrontal cortex of the owl monkey (Aotus trivirgatus): regional specialization in cell structure

Recent studies have revealed marked regional variation in pyramidal cell morphology in primate cortex. In particular, pyramidal cells in human and macaque prefrontal cortex (PFC) are considerably more spinous than those in other cortical regions. PFC pyramidal cells in the New World marmoset monkey, however, are less spinous than those in man and macaques. Taken together, these data suggest that the pyramidal cell has become more branched and more spinous during the evolution of PFC in only some primate lineages. This specialization may be of fundamental importance in determining the cognitive styles of the different species. However, these data are preliminary, with only one New World and two Old World species having been studied. Moreover, the marmoset data were obtained from different cases. In the present study we investigated PFC pyramidal cells in another New World monkey, the owl monkey, to extend the basis for comparison. As in the New World marmoset monkey, prefrontal pyramidal cells in owl monkeys have relatively few spines. These species differences appear to reflect variation in the extent to which PFC circuitry has become specialized during evolution. Highly complex pyramidal cells in PFC appear not to have been a feature of a common prosimian ancestor, but have evolved with the dramatic expansion of PFC in some anthropoid lineages.