Histological and histochemical effects after occlusion alteration in suprahyoid muscles

This study verified the effect of unilateral teeth extraction on the suprahyoid muscles in gerbils (Meriones unguiculatus). Ten adult male gerbils weighing about 50g had induced occlusal alterations by upper molar teeth extraction on the left side while the other ten animals were only subjected to surgical stress, control group. After 60 days, animals of both groups, experimental and control had the suprahyoid muscles removed and processed for histological and histochemical (adenosine triphosphatase (ATPase), nicotine adenine dinucleotide tetrazolium reductase (NADH-TR) and succinate dehydrogenase (SDH)) purposes. The fiber type area was estimated in % according to Weibel method (point-counting method) using a test-system. The myosinic ATPase pH 4.7 activity in the control group of the digastric, milohyoid and geniohyoid muscles presented a small area of type I fiber and a larger area of type IIa fibers; in the experimental group, significant contractile capacity alteration was not observed. Samples of the digastric, milohyoid and geniohyoid muscles, after SDH activity, showed a small area with high metabolic activity fibers, and a large area with intermediary and low metabolic activity fibers in the control group. The milohyoid muscle of the experimental group presented low metabolic fibers in a reduced area, in both sides, however without significant difference. In the experimental group, high metabolic fibers were observed on the left side in a reduced area in the geniohyoid muscle, but without statistical significance. Thus, the geniohyoid muscle did not change the metabolic activity after occlusal alteration. In conclusion, 60 days of unilateral malocclusion induced was able to alter the fibers oxidative activity of the suprahyoid muscles, however, it does not affect the contractile property of the fibers. The digastric muscle has adequate fibers to produce fast contraction and able to resist to fatigue in intermediate degrees, but became more fatigable after unilateral exodontia.     

Differential distribution of some extracellular matrix fibers in an experimentally denervated rat megaileum

Absence of enteric neurons is associated with thickening of the intestinal muscularis externa in Chagas' disease. The thickening is due to hyperplasia and hypertrophy of the smooth muscle cells and increased extracellular matrix components. The influence of the nervous system on the structure of the smooth muscle cells and its associated matrix has been poorly investigated. An experimental model of denervation of the ileum in rats was performed by application of the surfactant agent benzalkonium chloride that selectively destroys the myenteric plexus. Three months later, ileal tissue samples were obtained and studied by histochemistry and transmission electron microsocopy. Sham operated rats were used as controls. The diameter of collagen fibrils was evaluated in electron micrographs. The histopathological analysis showed thickening of the muscular layer. The thin and weakly arranged collagen and reticulin fibers surrounding the smooth muscle cells, observed in control cases by Picrosirius polarization (PSP) stain method, corresponded to a population of loosely packed thin collagen fibrils of uniform diameters (mean=29.16 nm) at the ultrastructural level. In contrast, the thick and strongly birefringent fibers around the muscle cells, observed in the treated group, stained by PSP, corresponded to densely packed thicker fibrils with large variation in diameter (mean=39.41 nm). Comparison of the data demonstrated statistically significant difference between the groups suggesting that the replacement of loosely arranged reticulin fibers by fibrous tissue (with typical collagen fiber), may alter the biomechanical function resulting in impairment of muscular contraction.     

Ultrastructure of the myotendinous junction of the medial pterygoid muscle of adult and aged Wistar rats

The myotendon junction (MTJ) is a specialised area into the muscle fibers where the sarcoplasmic membranes connect to the collagen fibers bundles. There are few data about plasticity of the MTJ in aging processes. The aim of this study is to analyse the ultrastructure characteristics of MTJ of medial pterygoid muscle of adult and aged rats. Employing the transmission electron microscopy method, twenty male rats Wistar (Rattus norvegicus) were divided into two groups: A (n = 10) with 12 months of age; B (n = 10) 24 months of age. The animals were anaesthetised with overdose the urethane (3 g/kg, i.p.) and sacrified during the perfusion with modified Karnovsky solution. The specimens were post-fixed in a 1% osmium tetroxide solution, dehydrated in ascending concentration of ethanol and embedded in Spurr resin. The thin sections, of 90 nm thick, were counterstained with uranyl acetate and lead citrate solution, and examined in a Jeol 1010 transmission electron microscope. The fine structure of the MTJ of group A revealed the defined interdigitations and disposed in several levels of deep formations containing the collagen fibers. In the group B, such structures did not observed, detecting the projections irregular in shape, and large of extra matrix with in aspect of remodelling. In conclusion it was possible to identify the plasticity of MTJ in the group B which presented several morphological alterations comparing to the adult animals. These data of group B suggested the occurrence of aging processes in the MTJ in rats.     

Evaluation of diffusional anisotropy and microscopic structure in skeletal muscles using magnetic resonance

The pulsed-gradient spin-echo (PGSE) nuclear magnetic resonance (NMR) method is used for detecting the diffusion of water molecules in biological tissues. Because tissues generally have diffusional anisotropy, their diffusion properties are denoted by a tensor. In this study, we evaluated the diffusional anisotropy and microscopic structure in atrophied skeletal muscles using the PGSE NMR method. The left sciatic nerve was severed in twelve 9-week-old rats. Neurotomy caused neurogenic muscular atrophy at the left gastrocnemius. At 2, 4 and 8 weeks after neurotomy, magnetic resonance signals were selectively acquired from a 2 x 2 x 2 mm(3) voxel, which was located on the left gastrocnemius. The diffusion tensor, the mean diffusivity (MD) and the fractional anisotropy (FA) were calculated from the signals. A theoretical model of the diffusion in muscles was derived from Tanner's equation. The muscle fiber diameter was estimated by fitting the model to the measured signals. The measurements were also performed for normal rats as controls. No significant difference was found in the MD and the estimated intracellular diffusion coefficient between the control group and the denervated group. The denervated group had significantly higher FA compared with the control group (P<.05). The estimated muscle fiber diameter of the denervated group was significantly smaller than the estimated value of the control group (P<.05). These differences were found at 8 weeks after neurotomy. The proposed method is effective for evaluating changes in the microscopic structure of skeletal muscles.     

Radiation response behaviour of Al codoped germano-silicate SM fiber at high radiation dose

Radiation response behaviour of Ge + Al doped SM fiber fabricated by the solution doping process has been studied at room temperature with respect to 1310 nm transmission wavelength under three different dose rates of 200, 400 and 600 Rad/min to compare with that of standard Er doped as well as Ge doped SM fibers. Their radiation sensitivity has been observed with variation of dose rates, transmission wavelength along with their recovery nature. Radiation response behaviour of Al doped SM fiber is found to be slightly non-linear in nature with very low dose rate dependency. No saturation level was found upto 13 Krad cumulative dose. Thermobleaching as well as photobleaching phenomena have also been studied. Gamma irradiated Al doped preform shows an absorption peak at around 300 nm due to generation of Al (E′) defect center and gets annihilated after thermobleaching process. Gamma irradiated Al doped SM fiber shows prominent photobleaching effect on their optical attenuation with respect to the 850 nm transmission wavelength. From ESR study resonance signals for Al³⁺ related radiation-induced defect centers are not clearly observed in this study. A very weak hyperfine pattern has been observed for gamma irradiated Al doped preform sample. The high radiation sensitivity along with linear response behaviour, low recovery and almost dose rate independence behaviour of the material system of Ge + Al codoped SM core optical fiber under gamma radiation shows their potential for application as fiber optic radiation sensor in comparison to the universal standard erbium doped SM fiber.     

Transplantation of bone-marrow-derived cells into a nerve guide resulted in transdifferentiation into Schwann cells and effective regeneration of transected mouse sciatic nerve

Peripheral nerves possess the capacity of self-regeneration after traumatic injury. Nevertheless, the functional outcome after peripheral-nerve regeneration is often poor, especially if the nerve injuries occur far from their targets. Aiming to optimize axon regeneration, we grafted bone-marrow-derived cells (BMDCs) into a collagen-tube nerve guide after transection of the mouse sciatic nerve. The control group received only the culture medium. Motor function was tested at 2, 4, and 6 weeks after surgery, using the sciatic functional index (SFI), and showed that functional recovery was significantly improved in animals that received the cell grafts. After 6 weeks, the mice were anesthetized, perfused transcardially, and the sciatic nerves were dissected and processed for transmission electron microscopy and light microscopy. The proximal and distal segments of the nerves were compared, to address the question of improvement in growth rate; the results revealed a maintenance and increase of nerve regeneration for both myelinated and non-myelinated fibers in distal segments of the experimental group. Also, quantitative analysis of the distal region of the regenerating nerves showed that the numbers of myelinated fibers, Schwann cells (SCs) and g-ratio were significantly increased in the experimental group compared to the control group. The transdifferentiation of BMDCs into Schwann cells was confirmed by double labeling with S100/and Hoechst staining. Our data suggest that BMDCs transplanted into a nerve guide can differentiate into SCs, and improve the growth rate of nerve fibers and motor function in a transected sciatic-nerve model.     

Effects of aging and maternal protein restriction on the muscle fibers morphology and neuromuscular junctions of rats after nutritional recovery

Changes in the nutritional status of mothers may predispose their offspring to neuromuscular disorders in the long term. This study evaluated the effects of maternal protein restriction during pregnancy and lactation on the muscle fibers and neuromuscular junctions (NMJs) of the soleus muscle in the offspring of rats at 365 days of age that had undergone nutritional recovery. Wistar rats were divided into two groups: control (CG) – the offspring of mothers fed a normal protein diet (17%) and restricted (RG) – offspring of mothers fed a low protein diet (6%). After lactation, the male pups received standard chow ad libitum. At 365 days, samples of soleus muscle were collected for muscle fiber analysis (HE staining, NADH-TR reaction and ultrastructure), intramuscular collagen quantification (picrosirius red staining) and NMJs analysis (non-specific esterase technique). The cross-sectional area of type I fibers was reduced by 20% and type IIa fibers by 5% while type IIb fibers increased by 5% in the RG compared to the CG. The percentage of intramuscular collagen was 19% lower in the RG. Disorganization of the myofibrils and Z line was observed, with the presence of clusters of mitochondria in both groups. Regarding the NMJs, in the RG there was a reduction of 10% in the area and 17% in the small diameter and an increase of 7% in the large diameter. The results indicate that the effects of maternal protein restriction on muscle fibers and NMJs seem to be long-lasting and irreversible.     

Effects of Combined Stretching and Clenbuterol on Disuse Atrophy in Rat Soleus Muscle

Background and Purpose: Clinically, disuse muscle atrophy is often seen among patients who are severely debilited and are on prolonged bed rest. Common physical therapy interventions are not successful in preventing disuse muscle atrophy early in the medical treatment of critically ill patients. In situations such as this, the use of a β₂-adrenergic agonist such as clenbuterol (Cb) may be of benefit in preventing atrophy. Also, recent studies have suggested that stretching is possible in preventing disuse muscle atrophy and the decline in muscle strength. The objective of this study was to evaluate the effects of Cb medication combined with stretching (ST) on rat soleus muscle (SOL) during the progression of disuse muscle atrophy. Subjects: Thirty-five male Wistar rats were used in this study. Methods: The rats were divided into five groups: control (CON), hindlimb-unweighting (HU) only, HU+ST, HU+Cb medication, and HU+ST+Cb groups. The right SOL in stretching groups was maintained a stretched position for one hour daily by passively dorsiflexing the ankle joint under non-anesthesia. The experimental period was 2 weeks. Results: In the ST group, peak twitch tension per cross-sectional area in soleus muscle was significantly larger than in the Cb group, while there was no significant difference between the CON and ST groups. The conversion of type I to type II fibers that was observed in the Cb group was not recognized in the combined ST and Cb group. Discussion and Conclusion: Distinct effect of combined stretching and Cb medication was not recognized statistically. The results indicate that Cb affects muscle morphological characteristics while stretching affects contractile properties. These data suggest that a combined ST and Cb intervention considered the type-specificity of muscle fiber may be need more consideration for preventing disuse muscle atrophy and the decline in muscle strength.     

集成光学条波导阵列与单模光纤阵列的联接

本文报告了一种新的集成光学条波导阵列与镶嵌在硅V槽中的单模光纤阵列耦合联接方法的设计考虑,导出了确定光纤正确位置及V型槽的几何尺寸的若干计算公式.并讨论了光纤与波导几何尺寸与耦合效率的关系.指出了这是实现单模光纤阵列与条波导阵列的固定联接的有效方法,它简化了波导与光纤的对准程序,即由五维调整简化为平面的一维调整.可实现多个波导和多个光纤的同时对准与固定.最大限度地利用了有效重叠面积,从而提高了光纤与条波导的耦合效率.一组典型的数据是单模光纤(芯径10μm)对单模波导(10μm×5μm)的耦合效率可达55%,而同样尺寸的波导对光纤的最大耦会效率可达86%.     

Short-term stromal alterations in the rat ventral prostate following alloxan-induced diabetes and the influence of insulin replacement

The stromal microenvironment is pivotal to prostate physiology and malign transformation. Diabetes leads to testosterone withdrawal and affects the prostate stromal compartment and smooth muscle cells in a similar way to that observed after castration. However the response of these cells and their involvement in extracellular matrix remodeling is not satisfactorily understood. We investigated the changes caused in the short term (one week) by alloxan-induced diabetes in the stromal components of the rat ventral prostate (VP) with an emphasis on morphological alterations of stromal cells, their conversion to a myofibroblast phenotype and the remodeling of extracellular matrix and the influence of insulin therapy. Adult male Wistar rats were assigned into untreated diabetic (n=12), insulin-treated (n=8) diabetic and control (n=10) groups. Diabetes was induced by means of the injection of alloxan (40 mg/kg b.w.), while the control animals received saline solution only. Insulin (5 UI) was administered daily for one week after diabetes diagnosis. Testosterone and estrogen plasma levels were determined. VP was analyzed using transmission electron microscopy. The main stromal cells were identified by means of light microscopy, using immunocytochemistry for specific markers - vimentin for fibroblasts, α-actin for smooth muscle cells (smc) and vimentin/calponin for myofibroblasts, following the estimation of their relative frequency and absolute volume by means of stereology. After one week diabetes led to a marked decrease in testosterone levels and an atrophy of about 35% in the VP. The relative frequency of smc and collagen fibers increased in the VP of diabetic rats but their absolute weight remained unchanged. Experimental diabetes promptly altered smc morphology which assumed at the ultrastructural level a shrunken appearance with the approximation of cytoplasmic dense bodies and also exhibited a decreased immunoreactivity to calponin. The conversion of stromal cells to a myofibroblast phenotype did not occur in alloxan-induced diabetes, as evaluated by double immunoreaction to calponin and vimentin. Insulin treatment maintained testosterone levels and preserved at least partly the cell morphology and collagen fiber organization of the prostate stroma in short-term diabetes. The apparent collagen increase observed by means of microscopic analysis in the stromal prostate compartment in the short term after diabetes is mainly associated with gland atrophy and does not involve the formation of new collagen fibers, the generation of myofibroblast-like cells or the acquisition of a secretory phenotype by stromal cells.     

Optical fibers and fiber dispersion compensators for high-speed optical communication

In order to meet the requirements necessary for advanced optical fiber transmission schemes that enable larger transmission capacity, higher efficiency and/or lower transmission costs per bit, optical fiber technologies are still evolving toward ultimate performance. Recent developmental activities have realized a number of improved performance optical fibers, such as ultra-low loss or ultra-low nonlinearity fibers and various types of dispersion-modified fibers. Fiber-based dispersion compensators or dispersion compensating fibers have also become one of the most essential optical components that support high-speed large capacity optical transmission. Very recently, the dispersion compensating fibers have further evolved into dispersion-managed optical transmission lines, which are now being actually deployed in transoceanic submarine optical cable networks.     

Force distributions and force chains in random stiff fiber networks

We study the elasticity of random stiff fiber networks. The elastic response of the fibers is characterized by a central force stretching stiffness as well as a bending stiffness that acts transverse to the fiber contour. Previous studies have shown that this model displays an anomalous elastic regime where the stretching mode is fully frozen out and the elastic energy is completely dominated by the bending mode. We demonstrate by simulations and scaling arguments that, in contrast to the bending dominated elastic energy, the equally important elastic forces are to a large extent stretching dominated. By characterizing these forces on microscopic, mesoscopic and macroscopic scales we find two mechanisms of how forces are transmitted in the network. While forces smaller than a threshold F_c are effectively balanced by a homogeneous background medium, forces larger than F_c are found to be heterogeneously distributed throughout the sample, giving rise to highly localized force chains known from granular media.     

Effect of unilateral extraction of molar teeth on suprahyoid muscles: macroscopic and ultrastructural aspects

Anatomical and physiologic components are parts of the stomatognathic system and their interaction results in integrated functional activities. Important alterations in the masticatory system originated by dental loss affect the bone, oral mucosa and muscular function. Dental arch structures specifically designed to receive and expose teeth allow performance of their functions. But the distinction between bony and soft tissues is lost when teeth are removed since there is not a specific function to be completed. The aim of this study was to evaluate the macroscopic and ultrastructural effects of the unilateral extraction of molar teeth on the suprahyoid muscles function, using twenty young male gerbils (Meriones unguiculatus) as the experimental animal model. They were divided in experimental malocclusion (n=10) and control (n=10) groups. The experimental malocclusion group was submitted to exodontia of the left upper molars and the control group was not submitted to this procedure and served as sham-operated. For macroscopic analysis of the suprahyoid muscle, the skin was uplifted and the muscles dissected individually and removed for weight analysis according to Scherle method. The electron microscopy analysis was made in ultra thin sections of small suprahyoid muscle fragments from the experimental and control groups, examined in a Jeol 1010, 880Kv transmission electron microscope. Several micrographs at magnifications of 3000x, 6000x, 30,000x were randomly selected for the qualitative analysis of the muscle fiber ultrastructures. Sixty days after the induced unilateral occlusal alteration no macroscopic morphologic changes was detected in the suprahyoid muscles and the muscle volume differences between the right and left sides and between groups were not significant. However, in the ultrastructural analysis suprahyoid muscles showed characteristics of specific adaptation to the unilateral occlusal alteration, by the reduced density of subsarcolemmal mitochondria and the shorter and less numerous ramifications in intermyofibrilar mitochondria localized between electronlucid myofibrils. It is concluded that unilateral exodontia of all the upper left molars affect the ultrastructural morphology of suprahyoid muscle fibers.     

Nineteen-port photonic lantern with multimode delivery fiber

We demonstrate efficient multimode (MM) to single-mode (SM) conversion in a 19-port photonic lantern with a 50 μm core MM delivery fiber. The photonic lantern can be used within the field of astrophotonics for coupling MM starlight to an ensemble of SM fibers in order to perform fiber-Bragg-grating-based spectral filtering. An MM delivery fiber spliced to the photonic lantern offers the advantage that the delivery fiber guides the light from the focal plane of the telescope to the splitter. Therefore, it is no longer necessary to have the splitter mounted directly in the focal plane of the telescope. The coupling loss from a 50 μm core MM fiber to an ensemble of 19 SM fibers and back to a 50 μm core MM fiber is below 1.1 dB.     

空分复用光纤研究综述

在多媒体和数据应用程序快速扩展和驱动骨干网带宽需求量迅速增长的网络背景下,时分、波分、偏分复用技术与多级调制方式结合,使得大容量传输系统中单模光纤容量快速接近香农理论极限。空分复用(SDM)技术可以突破该限制,为未来光纤容量增长提供新的解决方案。通过讨论多芯光纤、少模/多模光纤和少模多芯光纤三种SDM技术方案,详细介绍了SDM光纤的研究进展及研究方法,同时对三种光纤方案进行对比,阐明了各种方案的优劣性。     

Transmission capacity of erbium-doped fiber amplifiers as a criterion for quality of erbium-doped optical fibers

A new criterion—transmission capacity in the unsaturated gain regime—is proposed for comparing the quality of glasses for erbium-doped fiber amplifiers, considered as an element of an optical communication system. It is shown that, according to the criterion for the highest transmission capacity, amplifiers based on alumino-phosphate-silicate and zinc-sodium-germanate-silicate fibers are preferred for systems with separate C and L bands, respectively. In broadband systems, the highest transmission capacity is observed in amplifiers based on tellurite fibers.     

Magnetic resonance imaging of the normal and pathologic muscular system

Evaluation of the muscular system with magnetic resonance (MR) was conducted: (1) to assess the capability of MR to depict muscular abnormalities; (2) to evaluate the ability of MR to discriminate between various types of muscular pathologies based on relaxation parameters; and (3) to determine the optimal spin echo (SE) sequence that produced optimal contrast. Retrospective analysis was performed on 59 consecutive patients with a variety of muscular abnormalities. MR muscle analysis included visual inspection of contour and size; muscle intensity changes in relation to various TR/TE combinations; measurement of T1 and T2 relaxation and spin density; and calculation of percent contrast variation with different SE imaging combinations. Contour and size abnormalities were not reliable for detection of muscular pathology. For each individual subject intensity and relaxation times of all muscles involved by pathology differed from normal muscle. Although all pathologies caused increase in signal intensity of muscle, the alterations in relaxation times were variable. Fatty atrophy caused a decrease in T1 and increase in T2; while post-surgical changes, infection, acute intramuscular hemorrhage, and tumor invasion caused an increase in both T1 and T2. Percent contrast indicated that the optimum sequence for evaluation of fatty atrophy was a short (0.5 sec) repetition time (TR) and echo delay time (TE) of 56 msec, while for demonstration of the remaining muscular abnormalities, including post-surgical changes, infection, acute intramuscular hemorrhage, and tumor invasion, a long TR (TR = 2.0 sec) and TE (56 msec) was optimal. Differentiation between various benign and malignant muscular abnormalities (excluding fatty atrophy) was not possible using either quantitative intensity values or relaxation times.     

Ultrastructural characteristics of the gerbil pterygoid medial muscle after experimental occlusal alteration

Ten male young adult gerbils Meriones unguiculatus weighing 55g were divided in two groups: experimental (n=5) animals submitted to exodontia of the left upper molars, and sham-operated were used as control (n=5) group. The aim of the present study was to investigate the ultrastructural effects of occlusal alteration induced by unilateral exodontia on medial pterygoid muscle. After 60 days, the animals were sacrificed by perfusion intracardially with a modified Karnovsky solution after anesthetized with overdose of urethane (3g/kg i.p.). The small samples of this muscle were fixed in 2.5% glutaraldehyde solution and post-fixed in 1% buffered osmium tetroxide solution, dehydrated in ascending concentration of ethanol, and embedded in Spurr resin. Several micrographs data showed that in this period of time, the unilateral teeth extraction was able to induce modifications on the medial pterygoid muscle fibers and capillaries at ultrastructural levels as compared to control muscles and to the ones in the contralateral side of the experimental animals. Ultrastructural changes suggest that injury was greater in the hypofunctional muscle, ipsilateral to teeth extraction.     

单模光纤耦合器的偏振温度特性研究

理论分析并研究了温度变化对单模光纤耦合器的偏振特性的影响.推导了单模光纤耦合器输出消光比与输入消光比、模式耦合率的关系表达式.利用多个偏振特性不同的光源,进行了在快速温度变化条件下单模耦合器输出消光比随温度变化的测试实验,证明了采用低偏振的光源有利于降低单模耦合器中因温度变化引起的模式耦合效应.最后仿真计算了在光源输出消光比不同的情况下模式耦合引起的光纤陀螺输出误差的大小,为不同环境应用的光纤陀螺选取合适的光源提供了参考.