Simple and new surgical procedure for laryngotracheal separation in pediatrics.

OBJECTIVES: In children with severe physical and mental disabilities who repeatedly develop aspiration pneumonia due to intractable aspiration, laryngotracheal separation/tracheoesophageal anastomosis or laryngotracheal separation has been performed in many institutions for the prevention of aspiration, and good results have been reported. However, families sometimes show a marked reluctance to give consent to these surgical techniques because of tracheal transection. A purpose of this study is to evaluate a new surgical procedure for laryngotracheal separation without tracheal transection. STUDY DESIGN: Case-series study. METHODS: As a new, simple, less invasive surgical technique for the prevention of aspiration without tracheal transection, we performed tracheal closure (tracheal flap method) in six children. A U-shaped flap of the tracheal anterior wall from the 2nd to the 4th/5th tracheal ring was produced, bent toward the tracheal lumen, and sutured to the tracheal posterior/lateral walls by mattress stitches for tracheal closure. In addition, the closure was covered with a cutaneous U-shaped flap for reinforcement and a permanent tracheal stoma was constructed. RESULTS: In all six patients, aspiration pneumonia could be prevented without severe complications. CONCLUSIONS: Tracheal closure (tracheal flap method) has effects comparable to those of other surgical techniques for the prevention of aspiration, and may be useful for aspiration prevention in children with severe physical and mental disabilities.

A case of squamous cell carcinoma of the head and neck producing granulocyte-colony stimulating factor with marked leukocytosis.

In squamous cell carcinoma of the head and neck (SCCHN), tumor cells have been shown to secrete detectable amounts of various cytokines, such as interleukin (IL)-6, IL-10, and transforming growth factor (TGF)-beta. These tumor-derived factors might be responsible for promoting malignancy. Here, we describe a SCCHN patient with tumor produced G-CSF and characterized by marked leukocytosis. In this 45-year-old man, severe leukocytosis developed in parallel with aggressive tumor growth. G-CSF production by the tumor was confirmed by immunohistochemistry (IHC). Serum G-CSF levels were elevated. The leukocyte counts and the blood G-CSF level decreased following a course of radiotherapy. Tumor cells were also positive for G-CSF receptor, suggesting autocrine growth regulation by G-CSF. Moreover, the tumor cells were also investigated by IHC with anti-p53, anti-P-glycoprotein (P-gp), anti-thymidylate synthase (TS), and anti-dihydropyrimidine dehydrogenase (DPD), which molecules are thought to contribute the acquisition of therapeutic resistance. The tumor cells were positively stained for TS and DPD, but neither p53 nor P-gp. These results suggest that a variety of molecules may be responsible for acquisition of high malignancy.

Expression of thymidylate synthase and dihydropyrimidine dehydrogenase in adenoid cystic carcinoma of the head and neck: correlation with clinical outcome.

The purpose of this study was to estimate the possibility of using thymidylate synthase (TS), dihydropyrimidine dehydrogenase (DPD), and p53 as predictive values of clinical outcome in adenoid cystic carcinoma (ACC). The expressions of TS, DPD, and p53 were examined with immunohistochemistry in 27 ACC patients, and the association with clinicopathological factors was determined. Cases with high DPD expression had significantly higher distant metastasis rates compared to those with low DPD expression (p=0.001), whereas neither TS nor p53 expression showed any significant correlation to clinicopathological factors. Interestingly, six of 14 early-stage patients had distant metastases and all of their tumors showed high DPD expression. Kaplan-Meier analysis revealed that a solid histological pattern and distant metastasis correlated with a poor prognosis. In early-stage patients, whose tumor was completely resected, those with high TS or DPD expression had a worse prognosis compared to those with low expression, but the difference did not reach statistical significance (TS, p=0.178; DPD, p=0.251). Our results suggest that assessment of DPD expression in ACC may be a useful tool in determining the mode of treatment as well as evaluating clinical outcome.

CD47 promotes neuronal development through Src- and FRG/Vav2-mediated activation of Rac and Cdc42.

The development of axons and dendrites is controlled by small GTP-binding proteins of the Rho family, but the upstream signaling mechanisms responsible for such regulation remain unclear. We have now investigated the role of the transmembrane protein cluster of differentiation 47 (CD47) in this process with hippocampal neurons. CD47-deficient neurons manifested markedly impaired development of dendrites and axons, whereas overexpression of CD47 promoted such development. Interaction of SH2 domain-containing protein tyrosine phosphatase substrate-1 (SHPS-1) with CD47 also induced the formation of dendritic filopodia and spines. These effects of CD47 were prevented by inhibition of either cell division cycle 42 (Cdc42) or Rac. In CD47-deficient neurons, autophosphorylation of Src was markedly reduced. In addition, overexpression of CD47 promoted the autophosphorylation of Src. Inhibition of Src family kinases indeed prevented CD47-promoted dendritic development. Inhibition of either FGD1-related Cdc42-guanine nucleotide exchange factor (GEF) (FRG) or Vav2, which is a GEF for Cdc42 and Rac and is activated by Src, also prevented the effects of CD47 on dendritic development. These results indicate that CD47 promotes development of dendrites and axons in hippocampal neurons in a manner dependent, at least in part, on activation of Cdc42 and Rac mediated by Src as well as by FRG and Vav2.

Mucocele in an Onodi cell with simultaneous bilateral visual disturbance.

The Onodi cell is a large pneumatized posterior ethmoid cell and closely related to optic nerve. We present an extremely rare case of retrobulbar optic neuropathy caused by mucocele in an Onodi cell. A 79-year-old man complained of headaches and simultaneous bilateral visual disturbance. A computed tomography (CT) scan demonstrated a mucocele in an Onodi cell, which involved bilateral optic nerves. The surgical treatment with a transnasal endoscopic approach was performed, resulting in the improving of visual acuity. The bilateral optic nerves were identified along each lateral wall into an Onodi cell accompanied with bone defect. In an Onodi cell, even if the lesion is isolated and/or small, it may be closely related to ocular symptoms. Imaging studies should be considered for the differential diagnosis because early diagnosis and prompt surgical treatment for mucocele are needed for recovery of visual impairment.

Differential localization of Src homology 2 domain-containing protein tyrosine phosphatase substrate-1 and CD47 and its molecular mechanisms in cultured hippocampal neurons.

Polarized localization of membrane proteins to axons or dendrites is important for a variety of neuronal functions, including neurite outgrowth and synaptogenesis during neural development. Src homology 2 domain-containing protein tyrosine phosphatase (SHP) substrate-1 (SHPS-1) and its ligand cluster of differentiation 47 (CD47), both of which are members of the Ig superfamily of proteins, are thought to constitute an intercellular communication system in the CNS, although the physiological functions of this CD47-SHPS-1 system remain unknown. To provide insight into these functions, we have now examined the localization of SHPS-1 and CD47 in cultured hippocampal neurons. Endogenous SHPS-1 was detected at the surface of both axons and dendrites, whereas endogenous CD47 was localized predominantly to the surface of dendrites. Forced expression of these two proteins confirmed their distinct localizations. The extracellular regions of SHPS-1 and CD47 were responsible, at least in part, for their axonal and dendritic localizations, respectively; however, the axonal localization of SHPS-1 was not mediated by any one of the three Ig domains in its extracellular region. Overexpression of SHPS-1 and CD47 in distinct neurons resulted in marked accumulation of these proteins at sites of contact between SHPS-1-expressing axons and CD47-expressing dendrites. Such contact sites exhibited an enlarged structure but did not contain the synaptic marker protein vesicle-associated membrane protein-2. These results suggest that differential localization of SHPS-1 and CD47 at axons and dendrites generates a directional intercellular communication system that potentially contributes to regulation of synaptogenesis and the formation of neural networks.

Promotion of neurite and filopodium formation by CD47: roles of integrins, Rac, and Cdc42.

Axon extension during development is guided by many factors, but the signaling mechanisms responsible for its regulation remain largely unknown. We have now investigated the role of the transmembrane protein CD47 in this process in N1E-115 neuroblastoma cells. Forced expression of CD47 induced the formation of neurites and filopodia. Furthermore, an Fc fusion protein containing the extracellular region of the CD47 ligand SHPS-1 induced filopodium formation, and this effect was enhanced by CD47 overexpression. SHPS-1-Fc also promoted neurite and filopodium formation triggered by serum deprivation. Inhibition of Rac or Cdc42 preferentially blocked CD47-induced formation of neurites and filopodia, respectively. Overexpression of CD47 resulted in the activation of both Rac and Cdc42. The extracellular region of CD47 was sufficient for the induction of neurite formation by forced expression, but the entire structure of CD47 was required for enhancement of filopodium formation by SHPS-1-Fc. Neurite formation induced by CD47 was also inhibited by a mAb to the integrin beta3 subunit. These results indicate that the interaction of SHPS-1 with CD47 promotes neurite and filopodium formation through the activation of Rac and Cdc42, and that integrins containing the beta3 subunit participate in the effect of CD47 on neurite formation.

Tone burst-evoked myogenic potentials in rat neck extensor and flexor muscles.

Vestibular evoked myogenic potential (VEMP) has been used to test the vestibulocollic reflex. This study establishes a stable recording of VEMPs of animals, and presents useful parameters for vestibular ability. In an acute experiment, rats were decerebrated, and myogenic potential from neck extensor muscles was recorded. The myogenic potentials elicited by a tone-burst stimulus showed a biphasic response in the ipsilateral muscle, and the mean latency of the response was 3.56 ms, the positive peak appearing at 4.63 ms. The onset latencies of the response lengthen as the stimulus becomes weaker; this is the most suitable parameter of vestibular ability. The latencies of the monophasic response from the spinal cord were shorter than those of muscle. After injection of a muscle relaxant, myogenic potentials disappeared immediately, but the spinal cord response remained. We succeeded in recording responses not only from acute experimental animals but also from free-moving animals for the first time. These myogenic potentials were similar to VEMPs in humans; because the threshold of the response was higher than the auditory brainstem response threshold by 40-45 dB, the response could only be recorded with very high spontaneous muscle activity and the latency was shorter than the startle reflex.