|Kazu Kobayakawa||Last modified date：2021.05.29|
Assistant Professor / Orthopedic Surgery / Kyushu University Hospital
|Kazu Kobayakawa||Last modified date：2021.05.29|
|1.||Osamu Kawano, Takeshi Maeda, Hiroaki Sakai, Muneaki Masuda, Yuichiro Morishita, Tetsuo Hayashi, Kensuke Kubota, Kazu Kobayakawa, Kazuya Yokota, Hironari Kaneyama, Significance of the neurological level of injury as a prognostic predictor for motor complete cervical spinal cord injury patients, The Journal of Spinal Cord Medicine, 10.1080/10790268.2021.1903139, 1-7, 2021.04.|
|2.||Osamu Kawano, Takeshi Maeda, Eiji Mori, Tsuneaki Takao, Hiroaki Sakai, Muneaki Masuda, Yuichiro Morishita, Tetsuo Hayashi, Kensuke Kubota, Kazu Kobayakawa, Hironari Kaneyama, How much time is necessary to confirm the diagnosis of permanent complete cervical spinal cord injury?, Spinal Cord, 10.1038/s41393-019-0366-1, 58, 3, 284-289, 2020.03.|
|3.||Kazu Kobayakawa, Yasuyuki Ohkawa, Shingo Yoshizaki, Tetsuya Tamaru, Takeyuki Saito, Ken Kijima, Kazuya Yokota, Masamitsu Hara, Kensuke Kubota, Yoshihiro Matsumoto, Katsumi Harimaya, Keiko Ozato, Takahiro Masuda, Makoto Tsuda, Tomohiko Tamura, Kazuhide Inoue, V Reggie Edgerton, Yukihide Iwamoto, Yasuharu Nakashima, Seiji Okada, Macrophage centripetal migration drives spontaneous healing process after spinal cord injury., Science advances, 10.1126/sciadv.aav5086, 5, 5, eaav5086, 2019.05, Traumatic spinal cord injury (SCI) brings numerous inflammatory cells, including macrophages, from the circulating blood to lesions, but pathophysiological impact resulting from spatiotemporal dynamics of macrophages is unknown. Here, we show that macrophages centripetally migrate toward the lesion epicenter after infiltrating into the wide range of spinal cord, depending on the gradient of chemoattractant C5a. However, macrophages lacking interferon regulatory factor 8 (IRF8) cannot migrate toward the epicenter and remain widely scattered in the injured cord with profound axonal loss and little remyelination, resulting in a poor functional outcome after SCI. Time-lapse imaging and P2X/YRs blockade revealed that macrophage migration via IRF8 was caused by purinergic receptors involved in the C5a-directed migration. Conversely, pharmacological promotion of IRF8 activation facilitated macrophage centripetal movement, thereby improving the SCI recovery. Our findings reveal the importance of macrophage centripetal migration via IRF8, providing a novel therapeutic target for central nervous system injury..|
|4.||Kazu Kobayakawa, Kyleigh Alexis DePetro, Hui Zhong, Bau Pham, Masamitsu Hara, Akihito Harada, Jumpei Nogami, Yasuyuki Ohkawa, V Reggie Edgerton, Locomotor Training Increases Synaptic Structure With High NGL-2 Expression After Spinal Cord Hemisection., Neurorehabilitation and neural repair, 10.1177/1545968319829456, 33, 3, 225-231, 2019.03, BACKGROUND: We previously demonstrated that step training leads to reorganization of neuronal networks in the lumbar spinal cord of rodents after a hemisection (HX) injury and step training, including increases excitability of spinally evoked potentials in hindlimb motor neurons. METHODS: In this study, we investigated changes in RNA expression and synapse number using RNA-Seq and immunohistochemistry of the lumbar spinal cord 23 days after a mid-thoracic HX in rats with and without post-HX step training. RESULTS: Gene Ontology (GO) term clustering demonstrated that expression levels of 36 synapse-related genes were increased in trained compared with nontrained rats. Many synaptic genes were upregulated in trained rats, but Lrrc4 (coding NGL-2) was the most highly expressed in the lumbar spinal cord caudal to the HX lesion. Trained rats also had a higher number of NGL-2/synaptophysin synaptic puncta in the lumbar ventral horn. CONCLUSIONS: Our findings demonstrate clear activity-dependent regulation of synapse-related gene expression post-HX. This effect is consistent with the concept that activity-dependent phenomena can provide a mechanistic drive for epigenetic neuronal group selection in the shaping of the reorganization of synaptic networks to learn the locomotion task being trained after spinal cord injury..|
|5.||The acute phase serum zinc concentration is a reliable biomarker for predicting the functional outcome after spinal cord injury
© 2019 The Authors Background: Spinal cord injury (SCI) is a devastating disorder for which the accurate prediction of the functional prognosis is urgently needed. Due to the lack of reliable prediction methods, the acute evaluation of SCI severity and therapeutic intervention efficacy is extremely difficult, presenting major obstacles to the development of acute SCI treatment. We herein report a novel method for accurately predicting the functional prognosis using the acute-phase serum zinc concentration after SCI. Methods: We produced experimental animal SCI models with different prognoses and examined the relationship among the SCI severity, functional outcome, and acute-phase serum zinc concentration. We also examined whether we could predict the functional prognosis by evaluating the serum zinc concentration within 72 h after SCI in a human prospective study. Findings: In a mouse model, the acute serum zinc concentrations decreased in proportion to SCI severity and the serum zinc concentrations at 12 h after SCI accurately predicted the functional prognosis. We clarified the mechanism underlying this serum zinc proportional decrease, showing that activated monocytes took up zinc from blood-serum and then infiltrated the lesion area in a severity-dependent manner. A non-linear regression analysis of 38 SCI patients showed that the serum zinc concentrations in the acute-phase accurately predicted the long-term functional outcome (R 2 = 0·84) more accurately than any other previously reported acute-phase biomarkers. Interpretation: The acute-phase serum zinc concentration could be a useful biomarker for predicting the functional prognosis. This simple method will allow for more objective clinical trials and the development of patient-tailored treatment for SCI..
|6.||Pathological changes of distal motor neurons after complete spinal cord injury
© 2019 The Author(s). Traumatic spinal cord injury (SCI) causes serious disruption of neuronal circuits that leads to motor functional deficits. Regeneration of disrupted circuits back to their original target is necessary for the restoration of function after SCI, but the pathophysiological condition of the caudal spinal cord has not been sufficiently studied. Here we investigated the histological and biological changes in the distal part of the injured spinal cord, using a mice model of complete thoracic SCI in the chronic stage (3 months after injury). Atrophic changes were widely observed in the injured spinal cord both rostral and caudal to the lesion, but the decrease in area was mainly in the white matter in the rostral spinal cord while both the white and gray matter decreased in the caudal spinal cord. The number of the motor neurons was maintained in the chronic phase of injury, but the number of presynaptic boutons decreased in the lumbar motor neurons caudal to the lesion. Using laser microdissection, to investigate gene expressions in motor neurons caudal to the lesion, we observed a decrease in the expressions of neuronal activity markers. However, we found that the synaptogenic potential of postsynapse molecules was maintained in the motor neurons after SCI with the expression of acetylcholine-related molecules actually higher after SCI. Collectively, our results show that the potential of synaptogenesis is maintained in the motor neurons caudal to the lesion, even though presynaptic input is decreased. Although researches into SCI concentrate their effort on the lesion epicenter, our findings suggest that the area caudal to the lesion could be an original therapeutic target for the chronically injured spinal cord..
|7.||Astrocyte reactivity and astrogliosis after spinal cord injury
© 2017 Elsevier Ireland Ltd and Japan Neuroscience Society After traumatic injuries of the central nervous system (CNS), including spinal cord injury (SCI), astrocytes surrounding the lesion become reactive and typically undergo hypertrophy and process extension. These reactive astrocytes migrate centripetally to the lesion epicenter and aid in the tissue repair process, however, they eventually become scar-forming astrocytes and form a glial scar which produces axonal growth inhibitors and prevents axonal regeneration. This sequential phenotypic change has long been considered to be unidirectional and irreversible; thus glial scarring is one of the main causes of the limited regenerative capability of the CNS. We recently demonstrated that the process of glial scar formation is regulated by environmental cues, such as fibrotic extracellular matrix material. In this review, we discuss the role and mechanism underlying glial scar formation after SCI as well as plasticity of astrogliosis, which helps to foster axonal regeneration and functional recovery after CNS injury..
|8.||Takeyuki Saito, Masamitsu Hara, Hiromi Kumamaru, Kazu Kobayakawa, Kazuya Yokota, Ken Kijima, Shingo Yoshizaki, Katsumi Harimaya, Yoshihiro Matsumoto, Kenichi Kawaguchi, Mitsumasa Hayashida, Yutaka Inagaki, Keiichiro Shiba, Yasuharu Nakashima, Seiji Okada, Macrophage Infiltration Is a Causative Factor for Ligamentum Flavum Hypertrophy through the Activation of Collagen Production in Fibroblasts, AMERICAN JOURNAL OF PATHOLOGY, 10.1016/j.ajpath.2017.08.020, 187, 12, 2831-2840, 2017.12, Ligamentum flavum (LF) hypertrophy causes lumbar spinal canal stenosis, leading to leg pain and disability in activities of daily living in elderly individuals. Although previous studies have been performed on LF hypertrophy, its pathomechanisms have not been fully elucidated. In this study, we demonstrated that infiltrating macrophages were a causative factor for LF hypertrophy. Induction of macrophages into the mouse LF by applying a microinjury resulted in LF hypertrophy along with collagen accumulation and fibroblasts proliferation at the injured site, which were very similar to the characteristics observed in the severely hypertrophied LF of human. However, we found that macrophage depletion by injecting clodronate-containing liposomes counteracted LF hypertrophy even with microinjury. For identification of fibroblasts in the LF, we used collagen type I alpha(2) Linked to green fluorescent protein transgenic mice and selectively isolated green fluorescent protein-positive fibroblasts from the microinjured LF using laser microdissection. A quantitative RT-PCR on laser microdissection samples revealed that the gene expression of collagen markedly increased in the fibroblasts at the injured site with infiltrating macrophages compared with the uninjured location. These results suggested that macrophage infiltration was crucial for LF hypertrophy by stimulating collagen production in fibroblasts, providing better understanding of the pathophysiology of LF hypertrophy..|
|9.||Interaction of reactive astrocytes with type I collagen induces astrocytic scar formation through the integrin–N-cadherin pathway after spinal cord injury.|
|10.||Kazuya Yokota, Kazu Kobayakawa, Takeyuki Saito, Masamitsu Hara, Ken Kijima, Yasuyuki Ohkawa, Akihito Harada, Ken Okazaki, Kohei Ishihara, Shigeo Yoshida, Akira Kudo, Yukihide Iwamoto, Seiji Okada, Periostin Promotes Scar Formation through the Interaction between Pericytes and Infiltrating Monocytes/Macrophages after Spinal Cord Injury, AMERICAN JOURNAL OF PATHOLOGY, 10.1016/j.ajpath.2016.11.010, 187, 3, 639-653, 2017.03, Scar formation is a prominent pathological feature of traumatic central nervous system (CNS) injury, which has long been implicated as a major impediment to the CNS regeneration. However, the factors affecting such scar formation remain to be elucidated. We herein demonstrate that the extracellular matrix protein periostin (POSTN) is a key player in scar formation after traumatic spinal cord injury (SCI). Using high-throughput RNA sequencing data sets, we found that the genes involved in the extracellular region, such as POSTN, were significantly expressed in the injured spinal cord. The expression of POSTN peaked at 7 days after SCI, predominantly in the scar-forming pericytes. Notably, we found that genetic deletion of POSTN in mice reduced scar formation at the lesion site by suppressing the proliferation of the pericytes. Conversely, we found that recombinant POSTN promoted the migration capacity of the monocytes/macrophages and increased the expression of tumor necrosis factor-a from the monocytes/macrophages in vitro, which facilitated the proliferation of pericytes. Furthermore, we revealed that the pharmacological blockade of POSTN suppressed scar formation and improved the long-term functional outcome after SCI. Our findings suggest a potential mechanism whereby POSTN regulates the scar formation after SCI and provide significant evidence that POSTN is a promising therapeutic target for CNS injury..|
|11.||Takeyuki Saito, Kazuya Yokota, Kazu Kobayakawa, Masamitsu Hara, Kensuke Kubota, Katsumi Harimaya, Kenichi Kawaguchi, Mitsumasa Hayashida, Yoshihiro Matsumoto, Toshio Doi, Keiichiro Shiba, Yasuharu Nakashima, Seiji Okada, Experimental Mouse Model of Lumbar Ligamentum Flavum Hypertrophy, PLOS ONE, 10.1371/journal.pone.0169717, 12, 1, 2017.01, Lumbar spinal canal stenosis (LSCS) is one of the most common spinal disorders in elderly people, with the number of LSCS patients increasing due to the aging of the population. The ligamentum flavum (LF) is a spinal ligament located in the interior of the vertebral canal, and hypertrophy of the LF, which causes the direct compression of the nerve roots and/or cauda equine, is a major cause of LSCS. Although there have been previous studies on LF hypertrophy, its pathomechanism remains unclear. The purpose of this study is to establish a relevant mouse model of LF hypertrophy and to examine disease-related factors. First, we focused on mechanical stress and developed a loading device for applying consecutive mechanical flexion-extension stress to the mouse LF. After 12 weeks of mechanical stress loading, we found that the LF thickness in the stress group was significantly increased in comparison to the control group. In addition, there were significant increases in the area of collagen fibers, the number of LF cells, and the gene expression of several fibrosis-related factors. However, in this mecnanical stress model, there was no macrophage infiltration, angiogenesis, or increase in the expression of transforming growth factor-beta 1 (TGF-beta 1), which are characteristic features of LF hypertrophy in LSCS patients. We therefore examined the influence of infiltrating macrophages on LF hypertrophy. After inducing macrophage infiltration by micro-injury to the mouse LF, we found excessive collagen synthesis in the injured site with the increased TGF-beta 1 expression at 2 weeks after injury, and further confirmed LF hypertrophy at 6 weeks after injury. Our findings demonstrate that mechanical stress is a causative factor for LF hypertrophy and strongly suggest the importance of macrophage infiltration in the progression of LF hypertrophy via the stimulation of collagen production..|
|12.||The feasibility of in vivo imaging of infiltrating blood cells for predicting the functional prognosis after spinal cord injury
After a spinal cord injury (SCI), a reliable prediction of the potential functional outcome is essential for determining the optimal treatment strategy. Despite recent advances in the field of neurological assessment, there is still no satisfactory methodology for predicting the functional outcome after SCI. We herein describe a novel method to predict the functional outcome at 12 hours after SCI using in vivo bioluminescence imaging. We produced three groups of SCI mice with different functional prognoses: 50 kdyn (mild), 70 kdyn (moderate) and 90 kdyn (severe). Only the locomotor function within 24 hours after SCI was unable to predict subsequent functional recovery. However, both the number of infiltrating neutrophils and the bioluminescence signal intensity from infiltrating blood cells were found to correlate with the severity of the injury at 12 hours after SCI. Furthermore, a strong linear relationship was observed among the number of infiltrating neutrophils, the bioluminescence signal intensity, and the severity of the injury. Our findings thus indicate that in vivo bioluminescence imaging is able to accurately predict the long-term functional outcome in the hyperacute phase of SCI, thereby providing evidence that this imaging modality could positively contribute to the future development of tailored therapeutic approaches for SCI..
|13.||Disturbance of rib cage development causes progressive thoracic scoliosis the creation of a nonsurgical structural scoliosis model in mice
Background: The pathomechanism underlying idiopathic scoliosis remains unclear, and, to our knowledge, a consistent and relevant animal model has not been established previously. The goal of this study was to examine whether a disturbance of rib cage development is a causative factor for scoliosis and to establish a nonsurgical mouse model of progressive scoliosis. Methods: To examine the relationship between rib cage development and the pathogenesis of progressive scoliosis, a plastic restraint limiting anteroposterior rib cage development was placed on the chest of four-week-old mice. All mice were evaluated with whole-spine radiographs, and the severity of scoliosis was consecutively measured. The rib cage rotation angle and the anteroposterior chest dimension were measured with use of micro-computed tomography scanning. To examine whether the imbalanced load transmission through the ribs to the vertebral body was involved in our model, we performed a rib-neck osteotomy in a subgroup of the mice. Results: The thoracic restraint did not provoke spinal curvature immediately after it was applied, but nine of ten mice that wore the restraint but did not have rib osteotomy gradually developed progressive scoliosis. Radiographs and computed tomography images showed a right thoracic curvature, vertebral rotation, and narrow chest in the mice that had worn the restraint for eleven weeks but did not have rib osteotomy even after the restraint was removed. The anteroposterior chest dimension was significantly correlated with both the curve magnitude and the rib cage rotation angle. The progression of spinal deformity was observed only during the adolescent growth spurt, and it plateaued thereafter. The left-side rib osteotomy led to the development of progressive left-thoracic curvature, whereas the bilateral rib osteotomy did not cause scoliosis, even with restraint wear. Conclusions: We established a nonsurgical experimental model of progressive scoliosis and also demonstrated that a rib cage deformity with an imbalanced load to the vertebral body resulted in progressive structural scoliosis. Copyright © 2013 by the journal of bone and joint surgery, incorporated..
|14.||Therapeutic activities of engrafted neural stem/precursor cells are not dormant in the chronically injured spinal cord
The transplantation of neural stem/precursor cells (NSPCs) is a promising therapeutic strategy for many neurodegenerative disorders including spinal cord injury (SCI) because it provides for neural replacement or trophic support. This strategy is now being extended to the treatment of chronic SCI patients. However, understanding of biological properties of chronically transplanted NSPCs and their surrounding environments is limited. Here, we performed temporal analysis of injured spinal cords and demonstrated their multiphasic cellular and molecular responses. In particular, chronically injured spinal cords were growth factorenriched environments, whereas acutely injured spinal cords were enriched by neurotrophic and inflammatory factors. To determine how these environmental differences affect engrafted cells, NSPCs transplanted into acutely, subacutely, and chronically injured spinal cords were selectively isolated by flow cytometry, and their whole transcriptomes were compared by RNA sequencing. This analysis revealed that NSPCs produced many regenerative/ neurotrophic molecules irrespective of transplantation timing, and these activities were prominent in chronically transplanted NSPCs. Furthermore, chronically injured spinal cords permitted engrafted NSPCs to differentiate into neurons/oligodendrocytes and provided more neurogenic environment for NSPCs than other environments. Despite these results demonstrate that transplanted NSPCs have adequate capacity in generating neurons/oligodendrocytes and producing therapeutic molecules in chronic SCI microenvironments, they did not improve locomotor function. Our results indicate that failure in chronic transplantation is not due to the lack of therapeutic activities of engrafted NSPCs but the refractory state of chronically injured spinal cords. Environmental modulation, rather modification of transplanting cells, will be significant for successful translation of stem cell-based therapies into chronic SCI patients. © AlphaMed Press..
|15.||Ly6C+Ly6G-Myeloid-derived suppressor cells play a critical role in the resolution of acute inflammation and the subsequent tissue repair process after spinal cord injury
Acute inflammation is a prominent feature of central nervous system (CNS) insult and is detrimental to the CNS tissue. Although this reaction spontaneously diminishes within a short period of time, the mechanism underlying this inflammatory resolution remains largely unknown. In this study, we demonstrated that an initial infiltration of Ly6C+Ly6G-immature monocyte fraction exhibited the same characteristics as myeloid-derived suppressor cells (MDSCs), and played a critical role in the resolution of acute inflammation and in the subsequent tissue repair by using mice spinal cord injury (SCI) model. Complete depletion of Ly6C+Ly6G-fraction prior to injury by anti-Gr-1 antibody (clone: RB6-8C5) treatment significantly exacerbated tissue edema, vessel permeability, and hemorrhage, causing impaired neurological outcomes. Functional recovery was barely impaired when infiltration was allowed for the initial 24 h after injury, suggesting that MDSC infiltration at an early phase is critical to improve the neurological outcome. Moreover, intraspinal transplantation of ex vivo-generated MDSCs at sites of SCI significantly reduced inflammation and promoted tissue regeneration, resulting in better functional recovery. Our findings reveal the crucial role of an Ly6C+Ly6G-fraction as MDSCs in regulating inflammation and tissue repair after SCI, and also suggests an MDSC-based strategy that can be applied to acute inflammatory diseases. Myeloid-derived suppressor cells (MDSCs) exert immunosuppressive effects in several inflammatory diseases, including cancer and autoimmune disease. We demonstrated that Ly6C+Ly6G-myeloid cells which infiltrated into injured spinal cord had a typical feature of MDSCs and played a critical role in the attenuation of acute inflammation and the subsequent tissue repair process after spinal cord injury (SCI). Our findings clarified the role of MDSCs after traumatic SCI, and suggested a potential MDSC-based therapeutic strategy for the acute phase of central nervous system injury. © 2012 International Society for Neurochemistry..
|16.||Direct isolation and RNA-seq reveal environment-dependent properties of engrafted neural stem/progenitor cells
Neural stem/progenitor cell (NSPC) transplantation is a promising treatment for various neurodegenerative disorders including spinal cord injury, however, no direct analysis has ever been performed on their in vivo profile after transplantation. Here we combined bioimaging, flow-cytometric isolation and ultra-high-throughput RNA sequencing to evaluate the cellular properties of engrafted NSPCs. The acutely transplanted NSPCs had beneficial effects on spinal cord injury, particularly neuroprotection and neurohumoral secretion, whereas their in situ secretory activity differed significantly from that predicted in vitro. The RNA-sequencing of engrafted NSPCs revealed dynamic expression/splicing changes in various genes involved in cellular functions and tumour development depending on graft environments. Notably, in the pathological environment, overall transcriptional activity, external signal transduction and neural differentiation of engrafted NSPCs were significantly suppressed. These results highlight the vulnerability of engrafted NSPCs to environmental force, while emphasizing the importance of in situ analysis in advancing the efficacy and safety of stem cell-based therapies. © 2012 Macmillan Publishers Limited. All rights reserved..
|17.||Neurological recovery is impaired by concurrent but not by asymptomatic pre-existing spinal cord compression after traumatic spinal cord injury
STUDY DESIGN. An in vivo animal study to examine the influence of pre-existing or concurrent spinal canal stenosis (SCS) on the functional recovery after spinal cord injury (SCI). OBJECTIVES. To clarify whether spinal cord compression before or after SCI results in less favorable neurological recovery. SUMMARY OF BACKGROUND DATA. The influence of spinal cord compression on the neurological recovery after SCI remains unclear. METHODS. We created mice with SCS using an extradural spacer before or after producing SCI and statistically analyzed the correlation between the extent of SCS and neurological outcomes. The extent of SCS was calculated by micro-computed tomography, and the spinal cord blood flow (SCBF) was measured serially with laser Doppler flowmetry. Molecular and immunohistochemical examinations were performed to evaluate the neovascularization at the site of cord compression. RESULTS. Spacer placement (<300 μm) alone in the control mouse resulted in no neurological deficits. Even with spacer placement that caused asymptomatic SCS, the functional recovery after SCI was progressively impaired as spacer sizes increased in the mice with SCS co-occurring with SCI, whereas no significant impact was observed in the mice with pre-existing SCS, irrespective of the spacer sizes. The SCBF progressively decreased immediately after SCS was produced, but it fully recovered at the later time points. Angiogenesis-related genes were upregulated, and neovascular vessels were observed after producing the SCS. We found that concurrent SCS resulted in a significant reduction and impaired the subsequent recovery of the SCBF, whereas pre-existing SCS did not affect the hemodynamics of the spinal cord after SCI. CONCLUSION. The dynamic reduction of the SCBF occurring immediately after spinal cord compression is a significant factor that impairs the neurological recovery after SCI, whereas pre-existing SCS is not always an impediment due to the potentially restructured SCBF. © 2012, Lippincott Williams &Wilkins..
|18.||Liposomal clodronate selectively eliminates microglia from primary astrocyte cultures
Background: There is increasing interest in astrocyte biology because astrocytes have been demonstrated to play prominent roles in physiological and pathological conditions of the central nervous system, including neuroinflammation. To understand astrocyte biology, primary astrocyte cultures are most commonly used because of the direct accessibility of astrocytes in this system. However, this advantage can be hindered by microglial contamination. Although several authors have warned regarding microglial contamination in this system, complete microglial elimination has never been achieved.Methods: The number and proliferative potential of contaminating microglia in primary astrocyte cultures were quantitatively assessed by immunocytologic and flow cytometric analyses. To examine the utility of clodronate for microglial elimination, primary astrocyte cultures or MG-5 cells were exposed to liposomal or free clodronate, and then immunocytologic, flow cytometric, and gene expression analyses were performed. The gene expression profiles of microglia-eliminated and microglia-contaminated cultures were compared after interleukin-6 (IL-6) stimulation.Results: The percentage of contaminating microglia exceeded 15% and continued to increase because of their high proliferative activity in conventional primary astrocyte cultures. These contaminating microglia were selectively eliminated low concentration of liposomal clodronate. Although primary microglia and MG-5 cells were killed by both liposomal and free clodronate, free clodronate significantly affected the viability of astrocytes. In contrast, liposomal clodronate selectively eliminated microglia without affecting the viability, proliferation or activation of astrocytes. The efficacy of liposomal clodronate was much higher than that of previously reported methods used for decreasing microglial contamination. Furthermore, we observed rapid tumor necrosis factor-α and IL-1b gene induction in conventional primary astrocyte cultures after IL-6 stimulation, which was due to the activation of the Janus kinase/signal transducer and activator of the transcription pathway in contaminating microglia.Conclusions: Because contaminating microglia could result in erroneous data regarding the pro-inflammatory properties of astrocytes, astrocyte biology should be studied in the absence of microglial contamination. Our simple method will be widely applicable to experimental studies of astrocyte biology and provide clues for understanding the role of astrocytes in neural development, function and disease. © 2012 Kumamaru et al.; licensee BioMed Central Ltd..
|19.||Toshio Doi, Katsumi Harimaya, Hiromichi Mitsuyasu, Yoshihiro Matsumoto, Keigo Masuda, Kazu Kobayakawa, Yukihide Iwamoto, Right thoracic curvature in the normal spine, JOURNAL OF ORTHOPAEDIC SURGERY AND RESEARCH, 10.1186/1749-799X-6-4, 6, 2011.01, Background: Trunk asymmetry and vertebral rotation, at times observed in the normal spine, resemble the characteristics of adolescent idiopathic scoliosis (AIS). Right thoracic curvature has also been reported in the normal spine. If it is determined that the features of right thoracic side curvature in the normal spine are the same as those observed in AIS, these findings might provide a basis for elucidating the etiology of this condition. For this reason, we investigated right thoracic curvature in the normal spine.
Methods: For normal spinal measurements, 1,200 patients who underwent a posteroanterior chest radiographs were evaluated. These consisted of 400 children (ages 4-9), 400 adolescents (ages 10-19) and 400 adults (ages 20-29), with each group comprised of both genders. The exclusion criteria were obvious chest and spinal diseases. As side curvature is minimal in normal spines and the range at which curvature is measured is difficult to ascertain, first the typical curvature range in scoliosis patients was determined and then the Cobb angle in normal spines was measured using the same range as the scoliosis curve, from T5 to T12. Right thoracic curvature was given a positive value. The curve pattern was organized in each collective three groups: neutral (from -1 degree to 1 degree), right (> +1 degree), and left (< -1 degree).
Results: In child group, Cobb angle in left was 120, in neutral was 125 and in right was 155. In adolescent group, Cobb angle in left was 70, in neutral was 114 and in right was 216. In adult group, Cobb angle in left was 46, in neutral was 102 and in right was 252. The curvature pattern shifts to the right side in the adolescent group (p < 0.01) and in adult group (p < 0.001) compared to the child group. There was no significant difference in curvature pattern between adolescent and adult group.
Conclusions: Based on standing chest radiographic measurements, a right thoracic curvature was observed in normal spines after adolescence..