Daisuke Oyake

Penetrating neck injuries involving wooden foreign bodies: the role of MRI and the misinterpretation of CT images

A 12-year-old, boy fell in the bush and suffered a penetrating neck wound. Computed tomography(CT-scan) was performed, but no foreign body was detected inside the wound. The patient returned home after ordinary wound care. About 6 months after the accident, the patient visited hospital, because of inflammatory neck pain. A CT-scan was performed and the foreign body appeared as a high density. Magnetic resonance imaging (MRI) revealed the presence of a large foreign body. Under general anesthesia the wooden (bamboo) foreign body was removed. This case highlights the needs to be aware of the potential for misinterpretation of CT images, especially in acute wooden penetration injury. Its also demonstrates that MRI is a useful adjust to CT in the detection of non-metallic foreign bodies.

Inhibition of caspase-9 activity and Apaf-1 expression in cisplatin-resistant head and neck squamous cell carcinoma cells.

We have previously reported that cisplatin induces caspase-9 (Casp9) activation in head and neck squamous cell carcinoma cells in vitro (HNSCCs). Our purpose here was to examine whether HNSCCs selected for resistance to cisplatin fail to exhibit Casp9 activation in response to cisplatin. The cisplatin-resistant HNSCCs (HSC-2CR) were selected from cisplatin-sensitive HNSCCs (HSC-2) for growth in the presence of cisplatin. Following cisplatin treatment, protelyzed Casp9 subunits were detected in HSC-2, but not detected in HSC-2CR. Using a direct enzymatic assay measuring cleavage of the synthetic peptide substrate (LEHD-AFC), Casp9 activity in cisplatin-treated HSC-2CR was less than that in cisplatin-treated HSC-2. Apoptotic protease-activating factor 1 (Apaf-1) has been shown to participate as an adaptor molecule in Casp9 activation. In the presence of cytochrome c (Cyt c) released from mitochondria, Apaf-1 binds to Casp9 and causes its activation. HSC-2 expressed 2-fold higher levels of Apaf-1 compared with HSC-2CR. On the other hand, following cisplatin treatment, the same degree of increase in cytoplasmic Cyt c was detected in both HSC-2 and HSC-2CR. These results suggest that in a certain type of HNSCCs, the inhibition of Casp9 activity and Apaf-1 expression may represent a mechanism of acquired cisplatin resistance.

Targeted substrate degradation by an engineered double RING ubiquitin ligase.

Recognition of the substrates by ubiquitin ligases is crucial for substrate specificity in the ubiquitin-proteasome proteolytic pathway. In the present study, we designed a double RING finger ubiquitin ligase to direct the ubiquitin machinery to a specific substrate. The engineered ligase contains the RING finger domains of both BRCA1 and BARD1 linked to a substrate recognition site PCNA, which is known to interact with cyclin-dependent kinase inhibitor p57. The double RING finger ubiquitin ligase formed a homo-oligomer complex and exhibited significant ligase activity. Co-transfection of the ligase reduced the expression of transfected p57 to the background level in a proteasome-dependent manner and restored the colony formation ability of U2OS cells that is otherwise inhibited by overexpressed p57. The results indicate the ability of the engineered double RING ubiquitin ligase to target the intended substrate. By redesigning the substrate recognition site, expression of engineered double RING ubiquitin ligases may provide a useful tool for removing many different gene products at the protein level.

Rare localization of paraganglioma in head and neck

In this paper, we describe the clinical course of a 61-year-old female patient with paraganglioma in the head and neck region. Computed tomographic scan (CT), magnetic resonance imaging (MRI), ultrasound scan (US) and arteriogram findings initially led us to suspect that this tumor originated in the vagal nerve. In particular, a color Doppler US enabled an easy diagnosis of hypervascular tumor. We removed this surgically, but the tumor was easy to peel from the vagal nerve and carotid bifurcation. The distal side of the tumor was under the digastric muscle and running into the hypoglossal nerve. The intraoperative findings were highly suggestive of localization at the hypoglossal nerve, although Xth and XIIth cranial nerve palsies have remained.

Sensitization of head and neck squamous cell carcinoma cells to Fas-mediated apoptosis by the inhibition of Bcl-XL expression

BACKGROUND Various types of malignant tumor cells are known to acquire resistance to Fas receptor (Fas)-mediated apoptosis. In Fas-sensitive cells, Fas-mediated apoptosis is observed when anti-Fas antibody is bound to Fas. Bcl-2 and Bcl-X(L) are representative anti-apoptosis proteins reported to be capable of suppressing Fas-mediated apoptosis. OBJECTIVE To investigate the mechanism of resistance acquisition to Fas-mediated apoptosis in cultured human head and neck squamous cell carcinoma cells (HNSCCs). METHODS AND RESULTS We applied an anti-Fas antibody (CH11) to Fas-expressing HNSCCs (HSC-2) and the CH11 did not induce cell death in HSC-2. Treatment with actinomycin D (ActD) converted the phenotypes of HSC-2 from CH11-resistant to CH11-sensitive. Western blot analysis showed no differences between ActD-treated and ActD-untreated HSC-2 in the expression of Bcl-2. On the other hand, the expression of Bcl-X(L) was greatly reduced in ActD-treated HSC-2. Moreover, the reduction of Bcl-X(L) by specific antisense oligonucleotide treatment enhanced the CH11-induced cell death of HSC-2. CONCLUSION Our data suggest that Fas-signaling might be regulated by a Bcl-X(L)-inhibitable step in CH11-resistant HSC-2.

The Effect of the Power Setting of a Bipolar Radiofrequency System on Coagulation Range and Duration

The effect of the power setting of a bipolar radiofrequency system (CelonLab ENT) on coagulation range and duration was evaluated using chickens at power settings of 4, 8, 12, 16, 20, and 24W. Regression analysis revealed a significant correlation between coagulation range and power (P<0.0001, R2=0.71), with a larger area being coagulated at a lower power setting. There was also a significant correlation between coagulation time and power (P<0.0001, R2=0.75), with a shorter duration being required at a higher power setting. Although human and chicken tissue may exhibit different characteristics, our current results suggest that the power level should be altered by surgeons in accordance with coagulation requirements during a procedure.