Morphologic changes in the microcirculatory bed at stages of prolonged experimental fasting in animals

In 40 white male rats with body mass 180-200 g, by means of silver nitrate impregnation, morphological changes have been studied in the blood microcirculatory bed of the small intestine mesentery, spinal trapezoid muscle and eye ball conjunctiva at various stages of a prolonged fasting. With an increasing time of the experiment, a gradual undirected character of the changes in the microvessels is noted. After 3 days of fasting the changes in diameters of the microvessels, comparing to the control ones, have not any significant values in all the organs studied. After 6 days of fasting significant changes in diameters in all the links of the microcirculatory bed of the eye ball conjunctiva and in that of the spinal trapezoid muscle are observed. The microvascular changes are mostly pronounced on the 9th day of fasting. The maximal decrease of the microvessel diameters is noted in the eye ball conjunctiva, and the minimal--in the small intestine mesentery. The changes in the spinal trapezoid muscle are of intermediate character. The highest points of the structural lability gradient fall on the capillary and postcapillary-venular links of the blood microcirculatory bed.     

Changes in intervertebral disc morphology persist 5 mo after 21-day bed rest

As part of the nutrition-countermeasures (NUC) study in Cologne, Germany in 2010, seven healthy male subjects underwent 21 days of head-down tilt bed rest and returned 153 days later to undergo a second bout of 21-day bed rest. As part of this model, we aimed to examine the recovery of the lumbar intervertebral discs and muscle cross-sectional area (CSA) after bed rest using magnetic resonance imaging and conduct a pilot study on the effects of bed rest in lumbar muscle activation, as measured by signal intensity changes in T(2)-weighted images after a standardized isometric spinal extension loading task. The changes in intervertebral disc volume, anterior and posterior disc height, and intervertebral length seen after bed rest did not return to prebed-rest values 153 days later. While recovery of muscle CSA occurred after bed rest, increases (P ≤ 0.016) in multifidus, psoas, and quadratus lumborum muscle CSA were seen 153 days after bed rest. A trend was seen for greater activation of the erector spinae and multifidus muscles in the standardized loading task after bed rest. Greater reductions of multifidus and psoas CSA muscle and greater increases in multifidus signal intensity with loading were associated with incidence of low back pain in the first 28 days after bed rest (P ≤ 0.044). The current study contributes to our understanding of the recovery of the lumbar spine after 21-day bed rest, and the main finding was that a decrease in spinal extensor muscle CSA recovers within 5 mo after bed rest but that changes in the intervertebral discs persist.     

The Role of Histone Deacetylases I and IIa (HDAC1, HDAC4/5) and the MAPK38 Signaling Pathway in the Regulation of Atrophic Processes under Skeletal Muscle Unloading

Journal of Evolutionary Biochemistry and Physiology - Various forms of muscle unloading can be found in patients with prolonged bed rest, with strokes and spinal lesions, during muscle...     

Morphological changes in the spinal cord, its meninges and epidural structures in experimental disorders of blood flow in the venae cavae

The experiment has been carried out on 72 dogs. The dynamics of morphofunctional changes in the spinal cord, its meninges and in the epidural structures have been investigated when the epidural veins of the spinal canal are involved into the collateral blood stream after ligation of the anterior or posterior venae cavae. During the first 24 h after disturbance of the blood stream in the venae cavae, there appears venous stasis in the vessels of the epidural structures, of the spinal cord and its meninges, in neurons and glial elements hypoxia and acidosis appear. However, in connection with reconstruction of the collateralies, compensating the disturbed blood stream, by the end of the first week the phenomena of the venous stasis disappear. As the result of further reconstruction of the collateral bed, the epidural veins of the spinal canal become the main (short) bypass. During 3-5 months after occlusion of the venae cavae not only the ventral epidural veins of the spinal canal are gradually dilating, but the veins of the roots and meninges of the spinal cord, as well. The spinal cord edema develops, its volume increases by 10-18%, neural cells undergo severe morphological changes up to their death. The phenomena of a chronic venous congestion increase in their severity during 3 years, after that compensatory and restorative changes begin prevailing.     

Distribution of FMRFamide-like immunoreactivity in the central nervous system of the Formosan monkey (Macaca cyclopsis)

The distribution of FMRFamide-like immunoreactivity in the central nervous system of the Formosan monkey (Macaca cyclopsis) was investigated employing immunohistochemical techniques. FMRFamide-containing cells were found to be widely distributed throughout the forebrain. Principal densities of FMRFamide neuronal perikarya were observed in the following areas: the amygdaloid complex, the olfactory tubercle, the cerebral cortex, the basal ganglia, the septum, the caudate-putamen and the arcuate nucleus. A large number of immunoreactive fibers were observed in areas ranging from the cerebral cortex to the spinal cord, and were noted in the following locations: the preoptic area, the tuberal and posterior hypothalamic areas, the bed nucleus of the stria terminalis, the nuclei of the spinal trigeminal nerve, the hypoglossal nucleus, the nucleus of the solitary tract, and the dorsal horn of the spinal cord. The results generally parallel those described in the rat and guinea pig.     

Effect of gravitational loads of a training nature on the blood vessels of the rabbit spinal cord]

Three series of experiments were performed in 47 rabbits. The cerebral vessels were studied by methods of injection and clearing. In the first series under study were vessels after exposure to stresses of a training type. The picture of the circulatory bed under these conditions was close to normal in morphological parameters (diameter of vessels, amount of visible vessels, distinctness, evenness of the contours pronouncement of networks etc). In the 2nd and 3d series the results of training were checked by a single exposure to a series of stresses or a solitary stress. The data obtained suggest increased resistance in majority of trained animals to the following hypergravitation and better morphological parameters of the spinal cord circulatory bed as compared with not trained animals. Hence, certain adaptation to the following hypergravitation can be obtained in rabbits by means of repeated rotations in a centrifuge according to a special schedule of training.     

Exercise within lower body negative pressure partially counteracts lumbar spine deconditioning associated with 28-day bed rest.

Astronauts experience spine deconditioning during exposure to microgravity due to the lack of axial loads on the spine. Treadmill exercise in a lower body negative pressure (LBNP) chamber provides axial loads on the lumbar spine. We hypothesize that daily supine LBNP exercise helps counteract lumbar spine deconditioning during 28 days of microgravity simulated by bed rest. Twelve sets of healthy, identical twins underwent 6 degrees head-down-tilt bed rest for 28 days. One subject from each set of twins was randomly assigned to the exercise (Ex) group, whereas their sibling served as a nonexercise control (Con). The Ex group exercised in supine posture within a LBNP chamber for 45 min/day, 6 days/wk. All subjects underwent magnetic resonance imaging of their lumbar spine before and at the end of bed rest. Lumbar spinal length increased 3.7 +/- 0.5 mm in the Con group over 28-day bed rest, whereas, in the Ex group, lumbar spinal length increased significantly less (2.3 +/- 0.4 mm, P = 0.01). All lumbar intervertebral disk heights (L5-S1, L4-5, L3-4, L2-3, and L1-2) in the Con group increased significantly over the 28-day bed rest (P < 0.05). In the Ex group, there were no significant increases in L5-S1 and L4-5 disk heights. Lumbar lordosis decreased significantly by 3.3 +/- 1.2 degrees during bed rest in the Con group (P = 0.02), but it did not decrease significantly in the Ex group. Our results suggest that supine LBNP treadmill exercise partially counteracts lumbar spine lengthening and deconditioning associated with simulated microgravity.     

Vasopressinergic and oxytocinergic pathways in the central nervous system

Recent data obtained by immunohistochemical and other anatomical tracing methods indicate that oxytocin and vasopressin pathways are much more complex and extensive than previously recognized. In addition to the classic magnocellular neurons that project from the supraoptic and paraventricular (PVN) nuclei to the posterior pituitary gland, generally smaller neurons in various parts of the PVN send vasopressin fibers to the portal capillary bed in the median eminence, or send oxytocin or vasopressin projections to other brain and spinal cord sites. In addition, vasopressin neurons are also found in the suprachiasmatic nucleus and may contribute to extrahypothalamic projection areas. Many of these axonal projections appear to form synapses with other neurons in forebrain, hindbrain, and spinal cord regions, which suggests roles for these peptides in neuronal communication. In brain stem and spinal cord, terminal fields include both parasympathetic and sympathetic regulatory centers. Oxytocin terminals are also found on large intracerebral arteries where the peptide may regulate cerebral blood flow.     

Adaptation of the tendon to mechanical usage

Tendons primarily function as contractile force transmitters, but their mechanical properties may change dependent upon their level of mechanical usage. Using an ultrasound-based technique we have assessed tendon mechanical properties in vivo in a number of conditions representing different levels of mechanical usage. Ageing alters tendon mechanical properties; stiffness and modulus were lower in older adults by 10 and 14%, respectively, compared to young adults. Increased levels of exercise loading in old age can however partly reverse this process, as tendon stiffness and modulus were found to increase by 65 and 69%, respectively. Complete unloading due to bed rest or spinal cord injury both reduce tendon stiffness and modulus, however, only chronic unloading due to spinal cord injury seems to cause tendon atrophy. Alterations in tendon mechanical properties due to changes in the levels loading have implications for the speed of force transmission, the muscle's operating range and the likelihood of tendon strain injury.     

Quantitative distribution of calcitonin gene-related peptide in the rat central nervous system

Using an antiserum directed against human calcitonin gene-related peptide (hCGRP), which fully cross reacts with rat CGRP, a sensitive radioimmunoassay was developed. The antiserum was characterized by displacement curve characteristics and high performance liquid chromatography. The assay was applied to rat brain tissue and the concentration of CGRP for 48 microdissected brain areas is presented. Highest levels (1000–4500 fmol/mg protein) were found in the central amygdaloid, caudate putamen, and spinal trigeminal nerve nucleus and tract, substantia gelatinosa, and the dorsal horn of the spinal cord. Moderate levels (200–600 fmol/mg protein) were found in the bed nucleus of the stria terminalis, the subfornical organ, the paraventricular, arcuate, dorsomedial, dorsal parabrachial, ambiguus and tractus solitarii nuclei and in the median eminence. These results coincide with those previously obtained by immunohistochemistry. The widespread distribution in the brain suggests involvement of CGRP in a variety of behavioral functions.     

LBNP treadmill exercise maintains spine function and muscle strength in identical twins during 28-day simulated microgravity.

The purpose of this study was to determine whether lower body negative pressure (LBNP) treadmill exercise maintains lumbar spinal compressive properties, curvature, and back muscle strength after 28 days of 6 degrees head-down tilt (HDT) bed rest (BR). We hypothesize that LBNP treadmill exercise will maintain lumbar spine compressibility, lumbar lordosis and back muscle strength after 28 days of 6 degrees HDT bed rest. Fifteen healthy identical twin pairs (14 women and 16 men) participated in this study. One identical twin was randomly assigned to the nonexercise control (Con) group, and their sibling was assigned to the exercise (Ex) group. The lumbar spine was significantly more compressible Post-BR compared with Pre-BR in the Con (P=0.01). Lumbar spine compressibility Post-BR was not significantly different compared with Pre-BR in the Ex group (P=0.89). In both the Con and Ex groups, there were no significant changes Post-BR in lumbar lordosis compared with Pre-BR. Back muscle strength significantly decreased in the Con group Post-BR (P=0.002), whereas in the Ex group back muscle strength was not significantly different from Pre-BR values. A significant increase in lumbar spine compressibility in the Con group suggests that spinal deconditioning to gravity occurs during 28-day bed rest. Changes in the mechanical properties of the lumbar spine may be an early indicator of lumbar intervertebral disk degeneration. Supine LBNP treadmill exercise provides axial loads to the lumbar spine and may prevent lumbar spine deconditioning associated with HDT bed rest.     

Morphofunctional characteristics of the microcirculatory bed of the human spinal dura mater]

Some morphofunctional peculiarities in microcirculatory pathways of the dura mater of the human spinal cord are described. They are concerned with the structure of arteriolo-venular anastomoses through which a rather large amount of arterial blood is transported into the venous bed. Around the vessels of arterial type running at an angle to the longitudinal axis of the vessel connective tissue fibres of the dura mater, there is a tissue layer intensively impregnated with silver salts and stained PAS-positively. The venous part of the dura mater microcirculatory pathways has a large number of accessory reservoirs in the form of venous "lakes". Functional importance of the peculiarities mentioned above for the dura mater and the perimedullar apparatus is clarified.     

Autoradiographic distribution of I-galanin binding sites in the rat central nervous system

Galanin (GAL) binding sites in coronal sections of the rat brain were demonstrated using autoradiographic methods. Scatchard analysis of ¹²⁵I-GAL binding to slide-mounted tissue sections revealed saturable binding to a single class of receptors with a Kd of approximately 0.2 nM. ¹²⁵I-GAL binding sites were demonstrated throughout the rat central nervous system. Dense binding was observed in the following areas: prefrontal cortex, the anterior nuclei of the olfactory bulb, several nuclei of the amygdaloid complex, the dorsal septal area, dorsal bed nucleus of the stria terminalis, the ventral pallidum, the internal medullary laminae of the thalamus, medial pretectal nucleus, nucleus of the medial optic tract, borderline area of the caudal spinal trigeminal nucleus adjacent to the spinal trigeminal tract, the substantia gelatinosa and the superficial layers of the dorsal spinal cord. Moderate binding was observed in the piriform, periamygdaloid, entorhinal, insular cortex and the subiculum, the nucleus accumbens, medial forebrain bundle, anterior hypothalamic, ventromedial, dorsal premamillary, lateral and periventricular thalamic nuclei, the subzona incerta, Forel's field H₁ and H₂, periventricular gray matter, medial and superficial gray strata of the superior colliculus, dorsal parts of the central gray, peripeduncular area, the interpeduncular nucleus, substantia nigra zona compacta, ventral tegmental area, the dorsal and ventral parabrachial and parvocellular reticular nuclei. The preponderance of GAL-binding in somatosensory as well as in limbic areas suggests a possible involvement of GAL in a variety of brain functions.     

Ozone inhalation activates stress-responsive regions of the CNS

Ozone (O(3)), a major component of air pollution, has considerable impact on public health. Besides the well-described respiratory tract inflammation and dysfunctions, there is accumulating evidence indicating that O(3) exposure affects brain functions. However, the mechanisms through which O(3) exerts toxic effects on the brain remain poorly understood. This work aimed at precisely characterizing CNS neuronal activation after O(3) inhalation using Fos staining in adult rat. We showed that, together with lung inflammation, O(3) exposure caused a sustained time- and dose-dependent neuronal activation in the dorsolateral regions of the nucleus tractus solitarius overlapping terminal fields of lung afferents running in vagus nerves. Furthermore, we highlighted neuronal activation in interconnected central structures such as the caudal ventrolateral medulla, the parabrachial nucleus, the central nucleus of the amygdala, the bed nucleus of the stria terminalis and the paraventricular hypothalamic nucleus. In contrast, we did not detect any neuronal activation in the thoracic spinal cord where lung afferents running in spinal nerves terminate. Overall, our results demonstrate that O(3) challenge evokes a lung inflammation that induces the activation of nucleus tractus solitarius neurons through the vagus nerves and promotes neuronal activation in stress-responsive regions of the CNS.     

TLIF与PLIF对退行性腰椎滑脱合并腰椎管狭窄患者临床疗效及安全性比较

目的:比较经椎间孔椎体间融合术(transforaminal lumbar interbody fusion,TLIF)与经后路椎体间融合术(posterior lumbar interbody fusion,PLIF)对退行性腰椎滑脱合并腰椎管狭窄患者临床疗效及安全性。方法:选择2013年6月到2015年6月我院收治的90例退行性腰椎滑脱合并腰椎管狭窄患者,随机分为TLIF组和PLIF组,各45例。TLIF组患者给予TLIF治疗,PLIF组患者给予PLIF治疗。记录并比较两组患者手术时间、术中失血量、术后引流量及术后卧床时间。评价并比较两组患者治疗前后视觉疼痛评分(visual analogue scale,VAS)和Oswestry功能不良指数(oswestry disability index,ODI)。记录并比较两组患者治疗后神经根损伤、感染、硬膜囊破裂等并发症发生情况。结果:TLIF组患者的手术时间、术中失血量、术后引流量及术后卧床时间均明显小于PLIF组,均具有显著性差异(P0.05)。治疗前,两组患者VAS、ODI评分,相比均无显著性差异(P0.05);治疗后,两组患者VAS、ODI评分均明显小于治疗前,且TLIF组患者的VAS、ODI评分均明显小于PLIF组,均具有显著性差异(P0.05)。TLIF组患者的并发症发生率明显低于PLIF组,均具有显著性差异(X~2=3.873,P=0.049)。结论:相比于PLIF,TLIF治疗退行性腰椎滑脱合并腰椎管狭窄患者的临床疗效显著,有助于腰椎功能的恢复,并发症发生率较低,值得在临床上推广应用。     

改良后路腰椎体间融合术治疗腰椎管狭窄症的临床观察

目的:研究改良后路腰椎体间融合术(PLIF)治疗腰椎管狭窄症的临床疗效。方法:选取2010年7月到2014年7月我院收治的腰椎管狭窄症患者140例,按照随机数字表法将患者分为研究组和对照组,每组70例。研究组给予改良PLIF治疗,对照组给予传统PLIF治疗,比较两组手术时间、术中出血量、住院时间、术后下地时间,应用视觉模拟评分(VAS)评价术前、术后3个月、术后1年腰痛程度,应用Oswestry生活功能障碍指数(ODI)评分评价患者术前和术后1年的生活功能情况,并比较两组并发症的发生率。结果:两组手术时间、术中出血量比较无统计学意义(P0.05),研究组住院时间、术后下地时间显著短于对照组,差异具有统计学意义(P0.05);研究组术后3个月和术后1年VAS评分均显著低于对照组,差异具有统计学意义(P0.05);研究组术后1年ODI评分显著低于对照组,差异具有统计学意义(P0.05);研究组术后并发症发生率显著低于对照组,差异具有统计学意义(P0.05)。结论:改良PLIF治疗腰椎管狭窄症效果较PLIF好,能有效改善疼痛情况和日常生活,降低并发症的发生率。     

Autoradiographic distribution of 125I calcitonin gene-related peptide binding sites in the rat central nervous system

Using autoradiographic method and 125I-Tyro rat CGRP as a ligand, receptor binding sites were demonstrated in the rat central nervous system. Saturation studies and Scatchard analysis of CGRP-binding to slide mounted tissue sections containing primarily cerebellum showed a single class of receptors with a dissociation constant of 0.96 nM and a Bmax of 76.4 fmol/mg protein. 125I-Tyro rat CGRP binding sites were demonstrated throughout the rat central nervous system. Dense binding was observed in the telencephalon (medial prefrontal, insular and outer layers of the temporal cortex, nucleus accumbens, fundus striatum, central and inferior lateral amygdaloid nuclei, most caudal caudate putamen, organum vasculosum laminae terminalis, subfornical organ), the diencephalon (anterior hypothalamic, suprachiasmatic, arcuate, paraventricular, dorsomedial, periventricular, reuniens, rhomboid, lateral thalamic pretectalis and habenula nuclei, zona incerta), in the mesencephalon (superficial layers of the superior colliculus, central nucleus of the geniculate body, inferior colliculus, nucleus of the fifth nerve, locus coeruleus, nucleus of the mesencephalic tract, the dorsal tegmental nucleus, superior olive), in the molecular layer of the cerebellum, in the medulla oblongata (inferior olive, nucleus tractus solitarii, nucleus commissuralis, nuclei of the tenth and twelfth nerves, the prepositus hypoglossal and the gracilis nuclei, dorsomedial part of the spinal trigeminal tract), in the dorsal gray matter of the spinal cord (laminae I-VI) and the confines of the central canal. Moderate receptor densities were found in the septal area, the "head" of the anterior caudate nucleus, medial amygdaloid and bed nucleus of the stria terminalis, the pyramidal layers of the hippocampus and dentate gyri, medial preoptic area, ventromedial nucleus, lateral hypothalamic and ventrolateral thalamic area, central gray, reticular part of the substantia nigra, parvocellular reticular nucleus. Purkinje cell layer of the cerebellum, nucleus of the spinal trigeminal tract and gracile fasciculus of the spinal cord. The discrete distribution of CGRP-like binding sites in a variety of sensory systems of the brain and spinal cord as well as in thalamic and hypothalamic areas suggests a widespread involvement of CGRP in a variety of brain functions.     

Immobilization and bone structure in humans

Long-term immobilization is known to result in substantial bone loss. The present review examined the existing evidence for deterioration of bone structure during long-term disuse in humans. Paralysis due to spinal cord injury, long-term exposure to microgravity in space or tightly restricted mobility during bed rest provide reasonable models to assess the influence of immobilization on bone structure. Expectedly, the duration of immobilisation was the major determinant of bone loss, but irrespective of whether the skeletal unloading was due to irrecoverable paralysis, long-term spaceflight or bed rest, the mean pattern of structural deterioration of bone, mainly manifest as substantial cortical thinning and trabecular bone loss, was quite similar. However, skeletal responses to disuse can be highly variable between individuals. Apparently the relative decline in individual’s bone loading in relation to loading prior to immobilization accounts for inter-individual variation.     

The Regional Distribution and Chromatographic Characterisation of Neurotensin-Like Immunoreactivity in the Rat Central Nervous System

Abstract: Carboxy- and amino-terminal specific neurotensin antisera have been characterized and used to determine the nature of neurotensin-like immunoreactivity in the rat central nervous system. Using these antisera, together with the separation of neurotensin-like immunoreactivity on reversephase HPLC columns, it is clear that the majority of rat central nervous system neurotensin-like immunoreactivity is indistinguishable from the synthetic tridecapeptide. However, smaller amounts of carboxy- and amino-terminal neurotensin-like immunoreactivity were detected, which may correspond to carboxy- and amino-terminal fragments of neurotensin. In addition, using the amino-terminal directed neurotensin antiserum, a detailed distribution of neurotensin-like immunoreactivity in the rat central nervous system is described. Highest amounts were found in the hypothalamus, central amygdaloid nucleus, bed nucleus of the stria terminalis and the substantia gelatinosa of the spinal cord and of the trigeminal region.     

Do changes in spinal reflex excitability elicited by transcranial magnetic stimulation differ based on the site of cerebellar stimulation?

Abstract

Purpose: The present study aimed to investigate whether spinal reflex excitability is influenced by the site of cerebellar transcranial magnetic stimulation (C-TMS).

Materials and methods: Fourteen healthy volunteers (mean age: 24.6?±?6.6?years [11 men]) participated. Participants lay on a bed in the prone position, with both ankle joints fixed to prevent unwanted movement. Right tibial nerve stimulation was provided to elicit the H-reflex in the right soleus muscle. Conditioning transcranial magnetic stimulation (TMS) was delivered at one of the following sites 110?ms prior to tibial stimulation: right, central, or left cerebellum; midline parietal (Pz) region; or sham stimulation. A total of 10 test trials were included for each condition, in random order. The unconditioned and conditioned H-reflexes were measured during random inter-test trials, and the cerebellar spinal facilitation (CSpF) ratios for each site were calculated (the ratio of conditioned to unconditioned H-reflexes). CSpF ratios were compared among TMS sites.

Results: CSpF ratios were significantly higher at cerebellar sites than at the Pz site or during sham stimulation. However, there was no significant difference in CSpF ratio among cerebellar sites.

Conclusions: TMS conditioning over any part of the cerebellum facilitated the excitability of the spinal motoneuron pool. Facilitation of the H-reflex due to C-TMS may involve the effects of the bilateral descending tract of the spinal cord on the spinal motoneuron pool. Alternatively, direct brainstem stimulation may have activated portions of the bilateral descending tract of the spinal cord.