Thoracic Outlet Syndrome Caused by a Primary Tumour in the Brachial Plexus

Thoracic outlet syndrome (TOS) caused by a primary brachial plexus tumour is very rare. A male politician in his 40s presented with numbness, left limb pain and positive Wright and Roos test results. Magnetic resonance imaging (MRI) revealed a tumour located just below the clavicle, compressing the subclavian artery during left arm elevation. Despite concerns regarding postoperative nerve deficits, surgery was performed because of worsening symptoms during the election campaigns. The pathology report revealed a schwannoma. Few reports have described TOS caused by primary tumours of the brachial plexus. While the decision to perform surgery for primary tumours of the brachial plexus requires careful consideration, surgery may be indicated in cases where the tumour location causes such symptoms. Level of Evidence: Level V (Therapeutic).

Evaluation of Restricted Motion Area of the Median Nerve in Patients with Carpal Tunnel Syndrome: A New Measurement Method Using an Ultrasonographic Video Image

Background: The precise etiology of carpal tunnel syndrome (CTS) remains unclear. One of the accepted factors for CTS is the restriction of the median nerve. Previous reports using ultrasound had only observed and measured the movement of parts of the median nerve. In this study, we aimed to elucidate the difference in the movement of the entire median nerve in patients with CTS (before and after surgery) and healthy volunteers using a new measurement method. Methods: We expressed the amount of movement of the entire nerve by a new method creating the motion area of the median nerve (MAMn) from an ultrasonographic video image on the computer. We compared the MAMn, the real MAMn (RMMn) (the value obtained by subtracting the nerve cross-sectional area from the MAMn), and mobile ratio (MR) (the value obtained from dividing the MAMn by the nerve cross-sectional area) between six wrists of six cases of CTS (before and at an average of 3.5 months after surgery) and six wrists of six healthy volunteers. Results: During passive wrist flexion, the average MAMn, RMMn, and MR of healthy cases were 23.1 mm², 16.4 mm², and 3.52, respectively. The average MAMn, RMMn, and MR of cases of CTS were respectively 11.8 mm², 5.4 mm², and 1.86 preoperatively; and 16.2 mm², 7.3 mm², and 1.87, postoperatively. The MAMn, RMMn, and MR decreased more significantly in patients with CTS than in healthy volunteers (p < 0.01). The MAMn and RMMn increased postoperatively (p < 0.05), but the MR remained low. Conclusions: The new measurement method revealed that the mobility of the entire median nerve was significantly restricted in cases of CTS compared to healthy participants. However, after surgery, nerve restriction was not restored despite improvements in symptoms, suggesting that decreases in nerve mobility contribute to CTS but are not a direct cause of symptoms.

The Tenosynovitis of Fingers Associated with Transthyretin Amyloidosis

Background: Amyloidosis treatment has advanced rapidly along with the discovery of drugs to prevent amyloid deposition. Therefore, it is vital to detect amyloidosis at an early stage. Wild-type transthyretin, which can cause carpal tunnel syndrome, may also cause finger tenosynovitis. However, the correlation between wild-type transthyretin amyloid and finger tenosynovitis is unclear. Here, we investigated pathological and clinical findings for 20 patients with finger tenosynovitis who underwent operation at our hospital to determine the frequency of transthyretin amyloid deposition in idiopathic finger tenosynovitis.

Methods: To check for the presence of amyloid deposition, all specimens (tendon synovium tissue or flexor tendon sheath) resected during the operation were stained by the direct fast scarlet method. Amyloid-positive specimens were evaluated by immunohistochemical staining using an anti-transthyretin antibody. Patient characteristics were evaluated with respect to amyloid presence.

Results: Thirteen (65%) of 20 finger tenosynovitis cases had amyloid deposition. Nine (69.2%) of the 13 amyloid-positive cases exhibited extensive transthyretin staining and were considered to have transthyretin amyloid. Amyloid deposition was more frequent in men. The mean number of fingers with tenosynovitis was significantly higher in amyloid-positive cases (3.8 fingers) than in amyloid-negative cases (2.0 fingers).

Conclusions: Men with multiple finger tenosynovitis tended to have transthyretin amyloid deposition. Our results support that multiple finger tenosynovitis may serve as an initial indication of evaluation for transthyretin amyloidosis.

Isolated Axillary Nerve Rupture due to Closed Nondislocating Injury of the Shoulder in Contact Sports: A Report of 2 Cases

CASE

Axillary nerve rupture without shoulder joint fracture or dislocation in contact sports is very rare. To date, there has been no detailed report on such cases. We present 2 rare cases of axillary nerve rupture in contact sports who were successfully treated with free nerve grafting.

CONCLUSION

In contact sports, the deltoid muscle is sometimes paralyzed temporarily after a collision. However, similar to our cases, the axillary nerve can be lacerated without fracture or dislocation. It is necessary to watch the course of paralysis carefully and consider nerve reconstruction if it does not recover.

Impact of phrenic nerve paralysis on the surgical outcome of intercostal nerve transfer

Brachial plexus injuries (BPI) can be complicated by diaphragmatic paralysis (DP). This study determined the influence of DP on biceps brachii (BB) recovery after intercostal nerve transfer (ICNT) for BPI and investigated the respiratory complications of ICNT. The study included 100 patients, 84 showing no DP in preoperative and early postoperative chest radiographic images (non-DP group) and 16 with DP that persisted for over one year after surgery (DP group). The postoperative reinnervation time did not differ between groups. BB strength one year after surgery was lower in the DP group than non-DP group (p = 0.0007). No differences were observed 2-3 years after surgery. In the DP group, four patients had respiratory symptoms that affected daily activities and their outcomes deteriorated (p = 0.04). Phrenic nerve transfer should not be combined with ICNT in patients with poor respiratory function because of the high incidence of respiratory complications.

SOX10 transactivates S100B to suppress Schwann cell proliferation and to promote myelination

Schwann cells are an important cell source for regenerative therapy for neural disorders. We investigated the role of the transcription factor sex determining region Y (SRY)-box 10 (SOX10) in the proliferation and myelination of Schwann cells. SOX10 is predominantly expressed in rat sciatic nerve-derived Schwann cells and is induced shortly after birth. Among transcription factors known to be important for the differentiation of Schwann cells, SOX10 potently transactivates the S100B promoter. In cultures of Schwann cells, overexpressing SOX10 dramatically induces S100B expression, while knocking down SOX10 with shRNA suppresses S100B expression. Here, we identify three core response elements of SOX10 in the S100B promoter and intron 1 with a putative SOX motif. Knockdown of either SOX10 or S100B enhances the proliferation of Schwann cells. In addition, using dissociated cultures of dorsal root ganglia, we demonstrate that suppressing S100B with shRNA impairs myelination of Schwann cells. These results suggest that the SOX10-S100B signaling axis critically regulates Schwann cell proliferation and myelination, and therefore is a putative therapeutic target for neuronal disorders.

The identification of transcriptional targets of Ascl1 in oligodendrocyte development

The basic helix-loop-helix (bHLH) transcription factor Ascl1 plays crucial roles in both oligodendrocyte development and neuronal development; however, the molecular target of Ascl1 in oligodendrocyte progenitor cells (OPCs) remains elusive. To identify the downstream targets of Ascl1 in OPCs, we performed gene expression microarray analysis and identified Hes5 as a putative downstream target of Ascl1. In vivo analysis revealed that Ascl1 and Hes5 were coexpressed in early developmental oligodendrocytes in both the telencephalon and the ventral spinal cord. We also found that Hes5 expression was reduced in the OPCs of Ascl1 mutant mice. Furthermore, we demonstrated that Ascl1 directly binds to an E-box region within the Hes5 promoter and regulates Hes5 expression at the transcriptional level. Taken together, these in vivo and in vitro data suggest that Ascl1 induces Hes5 expression in a cell-autonomous manner. Considering the previously known function of Hes5 as a repressor of Ascl1, our data indicate that Hes5 is involved in the negative feedback regulation of Ascl1.

Hes1 functions downstream of growth factors to maintain oligodendrocyte lineage cells in the early progenitor stage

Expansion of the progenitor pool of oligodendrocytes (OLs) is a critical process for obtaining appropriate amounts of mature myelin-forming OLs in the developing and regenerating central nervous system. In vitro, fibroblast growth factor-2 (FGF2), together with platelet-derived growth factor (PDGF), is required to expand oligodendrocyte progenitor cells (OLPs) in an unlimited manner, maintaining them in the early progenitor stage. However, the intracellular mechanisms that prevent OLP maturation remain elusive. In order to investigate these mechanisms, we established a mouse OLP primary culture, which enabled us to undertake biochemical analyses. We found that the suppressive effects on maturation of early OLP to the late O4(+) progenitor by PDGF+FGF2 treatment was abrogated by Mek inhibitor, while transfecting cells with a constitutively active Mek1 construct prevented OLP maturation, suggesting that the Mek-Erk pathway is implicated in the effects of the growth factor treatment. The activation of Mek-Erk pathway promoted proliferation of OLP suggesting that cell cycle progression has suppressive effects to the maturation of OLP. Furthermore, molecular screening using DNA microarrays revealed that Hes1, a negative regulator of bHLH transcription factors, is one of the downstream molecules induced by PDGF+FGF2 treatment. We confirmed that forced activation of Mek-Erk pathway is sufficient to induce Hes1 expression and that Hes1, in turn, exerts suppressive effects on the maturation of OL lineage by itself. Our observations thus indicate that Mek-Erk pathway plays pivotal role in preventing early OLP maturation to late OLPs and the effect is mediated by cell cycle progression as well as Hes1 induction.

Hypoventilation during passive leg movement in spinal cord-injured humans

We examined ventilatory response during passive walking-like exercise in the standing posture in complete spinal cord-injured humans and found that ventilatory equivalent for O(2) uptake, which would be related to the sensation of breathlessness, was lower during passive exercise than during quiet standing.

Unusual blood pressure response during standing therapy in tetraplegic man

We report a case of an individual with cervical spinal cord injury who showed a unique blood pressure response during passive standing and passive walking-like leg movement, i.e., hypertension with standing and hypotension with leg movement.

A novel function of RING finger protein 10 in transcriptional regulation of the myelin-associated glycoprotein gene and myelin formation in Schwann cells

Myelin-associated glycoprotein (MAG) has been detected in Schwann cells prior to the onset of myelination, suggesting its functions in the initiation of myelination. However, transcriptional regulatory mechanisms of MAG remain to be elucidated. Here, we analyzed the promoter of the MAG gene by using luciferase reporter systems in the primary rat Schwann cells. We identified a novel cis-acting element located 160 bp upstream from the MAG transcription initiation site. Using the identified cis-element as a bait, we performed yeast one-hybrid screening and isolated a cDNA encoding a RNF10 as a putative trans-acting protein. When overexpressed in Schwann cells, RNF10 enhanced the activity of the MAG promoter. When RNF10 expression in Schwann cells was knocked down by siRNA, endogenous MAG mRNA and protein expression decreased. Furthermore, we evaluated myelin synthesis using Schwann cell-DRG neuron cocultures. When Schwann cells were infected with retrovirus expressing RNF10 siRNA, myelin formation was inhibited. These data suggest that RNF10 regulates MAG expression and is required for myelin formation.

Molecular mechanism of the life and death of the osteoclast

The life span of osteoclasts is critically regulated by various cytokines, and therapeutics such as bisphosphonates act directly on osteoclasts and induce apoptosis of the cells. This article will focus on the molecular mechanism of osteoclast apoptosis and summarize the recent advances in this field with an emphasis on the role of intracellular signaling pathways.

Spontaneous lymphocyt ic thyroiditis in interferon regulatory factor-1 deficient non-obese diabetic mice

Interferon regulatory factor-1 (IRF-1) is a transcription factor involved in interferon-mediated immune reaction, CD8+ T cell differentiation and development of T helper 1 immune reaction. We have recently demonstrated that IRF-1 is pivotal in iodine-induced lymphocytic thyroiditis (LT) in non-obese diabetic (NOD) mice. However, it remains unclear whether the mechanism involved in spontaneous LT is identical with iodine-induced LT in NOD mice. To determine the role of IRF-1 in spontaneous LT, we used IRF-1 deficient NOD mice as well as IRF-1 +/+ and +/- mice which were free from treatments for LT induction, and LT was evaluated at 24 weeks of age. IRF-1 +/+, +/- and -/- mice developed LT spontaneously, and there were no differences among the 3 IRF-1 genotypes in the incidence and severity of LT. Whereas both CD4+ and CD8+ T cells were present in the diseased thyroid of IRF-1 +/+ mice, CD8+ T cells were absent in the thyroid of IRF-1 -/- mice. MHC class II antigen expression was induced in the inflamed thyroid of IRF-1 -/- mice comparable to IRF-1 +/+ mice. There was a selective reduction in the number of CD8+ T cells in the spleen of IRF-1 -/- mice. IFNgamma production, but not IL-10, by concanavalin A-stimulated splenocytes was significantly reduced in IRF-1 deficient mice. These results suggest that IRF-1 plays only a minor role in spontaneous LT in NOD mice and, furthermore, the mechanism involved in spontaneous LT is different from that of iodine-induced LT in NOD mice.

Opposing extracellular signal-regulated kinase and Akt pathways control Schwann cell myelination

Schwann cells are the myelinating glia of the peripheral nervous system, and their development is regulated by various growth factors, such as neuregulin, platelet-derived growth factor (PDGF), and insulin-like growth factor-I (IGF-I). However, the mechanism of intracellular signaling pathways following these ligand stimuli in Schwann cell differentiation remains elusive. Here, we demonstrate that in cultured Schwann cells, neuregulin and PDGF suppressed the expression of myelin-associated protein markers, whereas IGF-I promoted it. Although these ligands activated common downstream signaling pathways [i.e., extracellular signal-regulated kinase (Erk) and phosphatidylinositol-3-kinase (PI3K)-Akt pathways], the profiles of activation varied among ligands. To elucidate the function of these pathways and the mechanisms underlying Schwann cell differentiation, we used adenoviral vectors to selectively activate or inactivate these pathways. We found that the selective activation of Erk pathways suppressed Schwann cell differentiation, whereas that of PI3K pathways promoted it. Furthermore, lithium chloride, a modulator of glycogen synthase kinase-3beta (GSK-3beta) promoted Schwann cell differentiation, suggesting the involvement of GSK-3beta as a downstream molecule of PI3K-Akt pathways. Selective activation of PI3K pathways in Schwann cells by gene transfer also demonstrated increased myelination in in vitro Schwann cell-DRG neuron cocultures and in vivo allogenic nerve graft experiments. We conclude that signals mediated by PI3K-Akt are crucial for initiation of myelination and that the effects of growth factors are primarily dependent on the balance between Erk and PI3K-Akt activation. Our results also propose the possibility of augmenting Schwann cell functions by modulating intracellular signals in light of future cell therapies.

Double-stranded RNA-induced interferon regulatory factor-1 gene expression in FRTL-5 rat thyroid cells

Double-stranded RNA (dsRNA) plays a role in the regulation of cell growth and apoptosis as well as in the cellular antiviral responses. However, it remains unknown if dsRNA-activated signaling systems are functional in the thyroid. Here we report the presence of the dsRNA-dependent protein kinase (PKR) in FRTL-5 rat thyroid cells. In poly(I)-poly(C) (pIC)-stimulated cells, activation of nuclear factor-kappa B (NF kappa B) binding was clearly induced. Incubation of FRTL-5 cells with pIC resulted in a marked increase in interferon regulatory factor-1 (IRF-1) mRNA and phosphorylated signal transducer and activator of transcription-1 (STAT1) levels. Addition of pIC to cells led to type I interferon (IFN) gene expression, especially IFN beta, which can induce STAT1 phosphorylation, suggesting that dsRNA indirectly induced STAT1 phosphorylation through expression of type I IFN. Thus, our results suggest that the dsRNA-activated signaling pathway may be involved in the regulation of IFN-inducible genes in the thyroid.