Surface morphology smoothing of a 2 inch-diameter GaN homoepitaxial layer observed by X-ray diffraction topography

We investigated the surface morphology changes in a 2 inch-diameter, c-plane, free-standing GaN wafer using X-ray diffraction topography in a grazing-incidence geometry. We observed a decrease in the peak intensity and increase in the full width at half maximum of the GaN 11$\bar{2}$4 Bragg peak after the deposition of a homoepitaxial layer on the same GaN wafer. However, the lattice plane bending angles did not change after homoepitaxial layer deposition. Distorted-wave Born approximation calculations near the total external reflection condition revealed a decrease in the X-ray incidence angle of the 11$\bar{2}$4 Bragg peak after the homoepitaxial layer deposition. The decrease in both X-ray penetration and incidence angle induced broader and weaker diffraction peaks from the surface instead of the bulk GaN.

We investigated the surface morphology changes in a 2 inch-diameter, c-plane, free-standing GaN wafer using X-ray diffraction topography in a grazing-incidence geometry.     

Immunohistochemical analysis of hepatic interferon alpha-beta receptor level: relationship between receptor expression and response to interferon therapy in patients with chronic hepatitis C

Background/Aims: This study aimed to determine the expression level of interferon alpha/beta (IFN-α/β) receptor in the liver immunohistochemically and evaluate its usefulness in predicting the outcome to IFN therapy in patients with chronic hepatitis C.Methods: The level of IFN-α/β receptor expression was determined in immunoperoxidase-stained pretreatment sections of 55 chronic hepatitis C patients later treated with IFN. We used liver biopsy specimens and mouse monoclonal anti-human IFN-α/β receptor antibody. Quantitative analysis of immunostaining was performed by image analysis software. The level of IFN-α/β receptor was expressed as Unit (U). Sustained responders were patients who showed persistent disappearance of serum HCV-RNA during the 6-month period after treatment, while non-responders showed persistence of viremia after therapy.Results: Positive immunostaining was observed in the cytoplasm of hepatocytes. The mean expression level of hepatic IFN-α/β receptor in sustained responders (2.65±1.11 U, n=15) was significantly (p<0.001) higher than in non-responders (1.61±1.05 U, n=40). A significant decrease in IFN-α/β receptor expression level was observed in patients with advanced liver fibrosis. In patients with low level viremia (pretreatment serum HCV-RNA <1 Meq/ml, n=18), the level of IFN-α/β receptor in sustained responders (2.89±1.12 U, n=11) was significantly (p<0.01) higher than in non-responders (0.93±0.33 U, n=7).Conclusions: Our results suggest that measurement of the level of hepatic IFN-α/β receptor in patients with chronic hepatitis C might be useful for predicting the response to IFN therapy. Resistance to IFN therapy in patients with chronic hepatitis C might be due to low levels of hepatic IFN-α/β receptor.     

Clinicopathological study of nonalcoholic fatty liver disease in Japan: the risk factors for fibrosis

Background/Aims: We evaluated patients with nonalcoholic fatty liver disease (NAFLD) and compared the clinical and pathological features to identify the risk factors for NAFLD with severe fibrosis. Methods: One hundred and eighty‐two patients with biopsy‐confirmed NAFLD from various medical centres were recruited into this study. Results: The variables that were significantly associated with severe steatosis were male gender (mild:severe=36%:53%, P=0.02), younger age (mild:severe=57%:82%, P>0.001) and absence of type 2 diabetes (mild:severe=43%:71%, P>0.001). There was no significant difference in the degree of inflammation among the clinical groups. The variables that were significantly associated with severe fibrosis were female gender (mild:severe=54%:84%, P=0.002), older age (≥60 years old) (mild:severe=29%:53%, P=0.020), type 2 diabetes (mild:severe=42%:71%, P=0.020) and hypertension (mild:severe=24%:53%, P=0.002). Although there were more obese patients in the group with severe fibrosis, the association was not statistically significant (mild:severe=67%:78%, P=0.229). The prevalence of high serum triglyceride levels was similar between the two groups. The N (Nippon) score (total number of risk factor) could significantly predict severe fibrosis in NAFLD patients (1.48 ± 1.14 vs. 2.66 ± 0.94, P<0.001). Conclusions: The N score can be used to predict severe fibrosis in cases of NAFLD.     

Influence of oral appliances on craniocervical posture in obstructive sleep apnea–hypopnea syndrome patients

PurposeThe existence of a relationship between head posture and mandibular function has been discussed by several authors. However, the relationship between head posture and the cervical spine in patients with obstructive sleep apnea–hypopnea syndrome (OSAHS) who are using oral appliances (OAs) remains unknown. The aim of this study was to evaluate the changes in the cervical spine associated with the use of OAs in patients with OSAHS.MethodsFifteen patients (4 females and 11 males; mean age, 48 years) diagnosed with OSAHS were randomly selected. An OA was fabricated individually for each patient. Two lateral cephalometric radiographs were taken while the patient was sitting awake in an upright position. The first radiograph was taken in the intercuspal position and the second was taken while the subject was wearing the OA. Analyses based on the sella–nasion (SN) line were performed in the lateral cephalogram. Comparison of craniocervical angles in patients with and without the OA was performed using Wilcoxon's signed-rank test.ResultsCephalometric analysis showed that the craniocervical angles (CVT-C2V and SN-C4) with OA were higher than those without OA (P < 0.05). It seems that the OA caused a significant flexion of the cranium on the upper cervical spine. A significant increase in the craniocervical angle occurred in the fourth cervical segment.ConclusionThe changes in forward flexion of the upper cervical spine found in this study imply that changes in the craniocervical relationship should be evaluated periodically after an OA has been inserted.     

Investigating the use of tie‐over dressing after skin grafting

Tie‐over bolster dressing after skin grafting can prolong operative time, and cause hematoma and seroma formation because of uneven pressure application. To describe the possibility of discontinuing the use of tie‐over dressing, we carried out a retrospective comparative study of patients who underwent skin grafting at an institution between January 2009 and December 2014. We investigated and compared the take rate, healing period, wound infection rate and hematoma formation rate for the tie‐over dressing group and the non‐tie‐over dressing group. Among 266 patients, 148 and 118 patients were included in the tie‐over dressing group and non‐tie‐over dressing group, respectively. There were no significant differences between the take rate, healing period, wound infection rate and hematoma formation rate for the two groups. Multivariate analysis showed that the complete graft take rate was not significantly influenced by tie‐over dressing, age, sex, graft site, graft procedure and skin graft diameter. Although the use of tie‐over dressing might remain necessary on sites with a free margin, including the eyelids, lips or nostrils, because of the difficulty in using tape fixation, the present study showed that alternative dressing with polyurethane foam is also useful in most cases of skin grafting.     

Optic nerve arteriovenous malformation causing optic apoplexy: case report

OBJECTIVE AND IMPORTANCE: Vascular malformations in the optic pathway are rare. Only one case of pathologically confirmed arteriovenous malformation (AVM) of the optic nerve has been reported previously. We document the case of a patient with an optic nerve AVM who presented with optic apoplexy that was diagnosed with the use of magnetic resonance imaging. CLINICAL PRESENTATION: A 15-year-old girl developed left visual disturbance of sudden onset while playing badminton. A magnetic resonance imaging scan disclosed left optic nerve swelling and intraoptical hemorrhage, although an angiogram did not reveal abnormal vessels. INTERVENTION: The patient underwent total removal of the hematoma and tangles of the abnormal vessels in the left optic nerve, which was diagnosed pathologically as an AVM. The patient recovered visual acuity, but the left visual field defect remained unchanged. CONCLUSION: Along with cavernous malformations and optic gliomas, AVMs can be a rare cause of optic nerve apoplexy. T2-weighted magnetic resonance imaging is useful in rendering the diagnosis of an optic nerve AVM, observed as a mass lesion consisting of serpiginous, tangled, low-intensity bands. Early surgical treatment is recommended to obtain a rapid recovery.