A numerical study of dehydration induced fracture toughness degradation in human cortical bone

A 2D plane strain extended finite element method (XFEM) model was developed to simulate three-point bending fracture toughness tests for human bone conducted in hydrated and dehydrated conditions. Bone microstructures and crack paths observed by micro-CT imaging were simulated using an XFEM damage model. Critical damage strains for the osteons, matrix, and cement lines were deduced for both hydrated and dehydrated conditions and it was found that dehydration decreases the critical damage strains by about 50%. Subsequent parametric studies using the various microstructural models were performed to understand the impact of individual critical damage strain variations on the fracture behavior. The study revealed the significant impact of the cement line critical damage strains on the crack paths and fracture toughness during the early stages of crack growth. Furthermore, a significant sensitivity of crack growth resistance and crack paths on critical strain values of the cement lines was found to exist for the hydrated environments where a small change in critical strain values of the cement lines can alter the crack path to give a significant reduction in fracture resistance. In contrast, in the dehydrated state where toughness is low, the sensitivity to changes in critical strain values of the cement lines is low. Overall, our XFEM model was able to provide new insights into how dehydration affects the micromechanisms of fracture in bone and this approach could be further extended to study the effects of aging, disease, and medical therapies on bone fracture.

Cell-free supernatant of Lactococcus lactis IDCC 2301 exerts anti-inflammatory effects in LPS-induced macrophages via NF-κB and MAPK signaling pathways

This study investigated the anti-inflammatory effects of cell-free supernatant of Lactococcus lactis IDCC 2301 on lipopolysaccharide (LPS)-induced RAW 264.7 macrophages. Expression of inflammatory mediators and cytokines, and the production of nitric oxide (NO) and prostaglandin E2 (PGE2) were qualitatively analysed. The expression of signal transductors in inflammatory cascades was quantified by western blot. Treatment with cell-free supernatant of L. lactis IDCC 2301 significantly decreased the mRNA expression levels of tumour necrosis factor (TNF-α) and interleukins including IL-1β and IL-6. The levels of inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX-2) were also remarkably reduced in LPS-induced macrophages after the treatment. Furthermore, L. lactis IDCC 2301 reduced the levels of both dephosphorylated and phosphorylated forms of nuclear factor-kappa B (NF-κB), IκB-α, extracellular signal-regulated kinases (ERK), c-Jun amino-terminal kinases (JNK), and p38 in LPS-induced RAW 264.7 cells. Therefore, L. lactis IDCC 2301 shows anti-inflammatory activity by suppressing the NF-κB and mitogen-activated protein kinase (MAPK) signaling pathways.

Profiles of central nervous system surgical site infections in endoscopic transnasal surgery exposing the intradural space

OBJECTIVE

Despite its efficacy and minimal invasiveness, the clean-contaminated nature of endoscopic transnasal surgery (ETS) may be susceptible to central nervous system surgical site infections (CNS-SSIs), especially when involving intradural exposure. However, the profiles of ETS-associated CNS-SSIs are not fully elucidated.

METHODS

The institutional ETS cases performed between May 2017 and March 2023 were retrospectively analysed. The incidences of CNS-SSIs were calculated, and their risk factors examined.

RESULTS

The incidence of CNS-SSIs was 2.3% (7/305) in the entire cohort and 5.0% (7/140) in ETSs with intradural exposure. All the CNS-SSIs were meningitis and developed following ETS with intradural exposure. The incidences were 0%, 5.6% and 5.8% in ETSs with Esposito grade 1, 2 and 3 intraoperative cerebrospinal fluid leakage, respectively. Among the pre- and intra-operative factors, body mass index (unit odds ratio (OR), 0.62; 95% confidence interval (CI), 0.44-0.89; P<0.01), serum albumin (unit OR, 0.03; 95% CI, 0.0007-0.92; P=0.02), and American Society of Anesthesiologists physical status score (unit OR, 20.7; 95% CI, 1.65-259; P<0.01) were significantly associated with CNS-SSIs. Moreover, postoperative cerebrospinal fluid leakage was also significantly associated with CNS-SSIs (OR, 18.4; 95% CI, 3.55-95.0; P<0.01).

CONCLUSIONS

The incidence of ETS-associated CNS-SSIs is acceptably low. Intradural exposure was a prerequisite for CNS-SSIs. Malnutrition and poor comorbidity status should be recognized as important risks for CNS-SSIs in ETS.

Impact of heavy alcohol consumption on cortical bone mechanical properties in male rhesus macaques

Chronic heavy alcohol consumption may influence the skeleton by suppressing intracortical bone remodeling which may impact the quality of bone and its mechanical properties. However, this aspect has not been thoroughly assessed in either humans or animal models whose cortical bone microstructure resembles the microstructure of human cortical bone. The current study is the first to investigate the effects of chronic heavy alcohol consumption on various mechanical properties of bone in a non-human primate model with intracortical remodeling. Male rhesus macaques (5.3 years old at the initiation of treatment) were induced to drink alcohol and then given the choice to voluntarily self-administer water or ethanol (4 % w/v) for approximately 14 months, followed by three abstinence phases (lasting 34, 41, and 39-46 days) with approximately 3 months of ethanol access in between. During the initial 14 months of open-access, monkeys in the alcohol group consumed an average of 2.9 ± 0.8 g/kg/d ethanol (mean ± SD) resulting in a blood ethanol concentration of 89 ± 47 mg/dl in longitudinal samples taken at 7 h after the daily sessions began. To understand the impact of alcohol consumption on material properties, various mechanical tests were conducted on the distal tibia diaphysis of 2-5 monkeys per test group, including dynamic mechanical analysis (DMA) testing, nano-indentation, microhardness testing, compression testing, and fracture resistance curve (R-curve) testing. Additionally, compositional analyses were performed using Fourier-transform infrared (FTIR) spectroscopy. Significant differences in microhardness, compressive stress-strain response, and composition were not observed with alcohol consumption, and only minor differences were detected in hardness and elastic modulus of the matrix and osteons from nanoindentation. Furthermore, the R-curves of both groups overlapped, with similar crack initiation toughness, despite a significant decrease in crack growth toughness (p = 0.032) with alcohol consumption. However, storage modulus (p = 0.029) and loss factor (p = 0.015) from DMA testing were significantly increased in the alcohol group compared to the control group, while loss modulus remained unchanged. These results indicate that heavy alcohol consumption may have only a minor influence on the material properties and the composition of cortical bone in young adult male rhesus macaques.

Effect of gamma irradiation and supercritical carbon dioxide sterilization with Novakill™ or ethanol on the fracture toughness of cortical bone

Sterilization of structural bone allografts is a critical process prior to their clinical use in large cortical bone defects. Gamma irradiation protocols are known to affect tissue integrity in a dose dependent manner. Alternative sterilization treatments, such as supercritical carbon dioxide (SCCO2 ), are gaining popularity due to advantages such as minimal exposure to denaturants, the lack of toxic residues, superior tissue penetration, and minor impacts on mechanical properties including strength and stiffness. The impact of SCCO2 on the fracture toughness of bone tissue, however, remains unknown. Here, we evaluate crack initiation and growth toughness after 2, 6, and 24 h SCCO2 -treatment using Novakill™ and ethanol as additives on ~11 samples per group obtained from a pair of femur diaphyses of a canine. All mechanical testing was performed at ambient air after 24 h soaking in Hanks' balanced salt solution (HBSS). Results show no statistically significant difference in the failure characteristics of the Novakill™-treated groups whereas crack growth toughness after 6 and 24 h of treatment with ethanol significantly increases by 37% (p = .010) and 34% (p = .038), respectively, compared to an untreated control group. In contrast, standard 25 kGy gamma irradiation causes significantly reduced crack growth resistance by 40% (p = .007) compared to untreated bone. FTIR vibrational spectroscopy, conducted after testing, reveals a consistent trend of statistically significant differences (p < .001) with fracture toughness. These trends align with variations in the ratios of enzymatic mature to immature crosslinks in the collagen structure, suggesting a potential association with fracture toughness. Additional Raman spectroscopy after testing shows a similar trend with statistically significant differences (p < .005), which further supports that collagen structural changes occur in the SCF-treated groups with ethanol after 6 and 24 h. Our work reveals the benefits of SCCO2 sterilization compared to gamma irradiation.

Regional and annual patterns in respiratory virus co-infection etiologies and antibiotic prescriptions for pediatric mycoplasma pneumoniae pneumonia

OBJECTIVE

Mycoplasma pneumoniae (M. pneumoniae) pneumonia is the second-most common cause of community-acquired pneumonia (CAP). This study aimed at investigating into the prevalence of macrolide-resistant M. pneumoniae (MRMP) with respiratory virus co-infection and the antibiotic prescriptions in children with CAP in four provinces in Korea, and to assess the variations in the findings across regions and throughout the year.

PATIENTS AND METHODS

This prospective study was conducted in 29 hospitals in Korea between July 2018 and June 2020. Among the enrolled 1,063 children with CAP, all 451 patients with M. pneumoniae underwent PCR assays of M. pneumoniae and respiratory viruses, and the presence of point mutations of residues 2063 and 2064 was evaluated.

RESULTS

Gwangju-Honam (88.6%) showed the highest prevalence of MRMP pneumonia, while Daejeon-Chungcheong (71.3%) showed the lowest, although the differences in prevalence were not significant (p=0.074). Co-infection of M. pneumoniae pneumonia and respiratory virus was observed in 206 patients (45.4%), and rhinovirus co-infection (101 children; 22.2%) was the most frequent. The prevalence of MRMP pneumonia with respiratory virus co-infection and the antibiotic prescriptions differed significantly among the four provinces (p < 0.05). The monthly rate of MRMP pneumonia cases among all cases of M. pneumoniae pneumonia and tetracycline or quinolone prescriptions did not differ significantly among the four regions (trend p > 0.05) during the study period.

CONCLUSIONS

The prevalence of M. pneumoniae pneumonia with virus co-infection and antibiotic prescriptions could differ according to region, although the MRMP pneumonia rate showed no difference within Korea.

ABHD6 Inhibition Rescues a Sex-Dependent Deficit in Motor Coordination in The HdhQ200/200 Mouse Model of Huntington's Disease

Huntington's Disease is associated with motor behavior deficits that are lessened by few therapeutic options. This preliminary study tested if pharmacological inhibition of α/β-hydrolase domain containing 6 (ABHD6), a multifunctional enzyme expressed in the striatum, rescues behavioral deficits in HdhQ200/200 mice. Previous work has shown that this model exhibits a reduction in spontaneous locomotion and motor coordination at 8 and 10 months of age, with a more severe phenotype in female mice. Semi-quantitative immunohistochemistry analysis indicated no change in striatal ABHD6 expression at 8 months of age, but a 40% reduction by 10 months in female HdhQ200/200 mice compared to female wild-type (WT) littermates. At 8 months of age, acute ABHD6 inhibition rescued motor coordination deficits in female HdhQ200/200 mice without affecting WT performance. ABHD6 inhibition did not impact spontaneous locomotion, grip strength, or overall weight in either group, showing that effects were specific to motor coordination. At 10 months of age, semi-chronic ABHD6 inhibition by osmotic pump delivery also rescued motor coordination deficits in female HdhQ200/200 mice without affecting female WT littermates. Our preliminary study suggests that ABHD6 inhibition improves motor performance in female HdhQ200/200 mice.

Genomic characterization and probiotic potential of Lactobacillus casei IDCC 3451 isolated from infant faeces

Probiotics play an important role in health benefits on the host. However, they also possess potentials for infectivity or in situ toxin production; thus, requiring a comprehensive assessment of their safety. In this study, we report genomic characteristics of a newly isolated Lactobacillus casei IDCC 3451 from infant faeces. Phenotypic assays based on enzyme activities and carbohydrate fermentation profiles represented metabolic features of the strain. Safety evaluation for antimicrobial resistance, biogenic amines production and cytotoxicity to a murine mouse model suggested its safe use as a probiotic strain. Our findings on the genetic background of L. casei IDCC 3451 and its potential features provide a promising functional and safe probiotic strain for the human consumption.

Ambient air pollution and in vitro fertilization treatment outcomes

STUDY QUESTION

Is air pollution associated with IVF treatment outcomes in the USA?

SUMMARY ANSWER

We did not find clear evidence of a meaningful association between reproductive outcomes and average daily concentrations of particulate matter with an aerodynamic diameter ≤2.5 μm (PM2.5) and ozone (O3).

WHAT IS KNOWN ALREADY

Maternal exposure to air pollution such as PM2.5, nitrogen oxides, carbon monoxide or O3 may increase risks for adverse perinatal outcomes. Findings from the few studies using data from IVF populations to investigate associations between specific pollutants and treatment outcomes are inconclusive.

STUDY DESIGN, SIZE AND DURATION

Retrospective cohort study of 253 528 non-cancelled fresh, autologous IVF cycles including 230 243 fresh, autologous IVF cycles with a transfer of ≥1 embryo was performed between 2010 and 2012.

PARTICIPANTS/MATERIALS, SETTING, METHODS

We linked 2010-2012 National ART Surveillance System data for fresh, autologous IVF cycles with the ambient air pollution data generated using a Bayesian fusion model available through the Centers for Disease Control and Prevention's Environmental Public Health Tracking Network. We calculated county-level average daily PM2.5 and O3 concentrations for three time periods: cycle start to oocyte retrieval (T1), oocyte retrieval to embryo transfer (T2) and embryo transfer +14 days (T3). Multivariable predicted marginal proportions from logistic and log-linear regression models were used to estimate adjusted risk ratios (aRR) and 95% CI for the association between reproductive outcomes (implantation rate, pregnancy and live birth) and interquartile increases in PM2.5 and O3. The multipollutant models were also adjusted for patients and treatment characteristics and accounted for clustering by clinic and county of residence.

MAIN RESULTS AND THE ROLE OF CHANCE

For all exposure periods, O3 was weakly positively associated with implantation (aRR 1.01, 95% CI 1.001-1.02 for T1; aRR 1.01, 95% CI 1.001-1.02 for T2 and aRR 1.01, 95% CI 1.001-1.02 for T3) and live birth (aRR 1.01, 95% CI 1.002-1.02 for T1; aRR 1.01, 95% CI 1.004-1.02 for T2 and aRR 1.02, 95% CI 1.004-1.03 for T3). PM2.5 was not associated with any of the reproductive outcomes assessed.

LIMITATIONS, REASONS FOR CAUTION

The main limitation of this study is the use of aggregated air pollution data as proxies for individual exposure. The weak positive associations found in this study might be related to confounding by factors that we were unable to assess and may not reflect clinically meaningful differences.

WIDER IMPLICATIONS OF THE FINDINGS

More research is needed to assess the impact of air pollution on reproductive function.

STUDY FUNDING/COMPETING INTEREST(S)

None.

P02.01 Analysis of Multimodal Intraoperative Monitoring During Intramedullary Spinal Ependymoma Surgery

BACKGROUND

To evaluate the validity of intraoperative somatosensory-evoked potential (SSEP) and motor-evoked potential (MEP) monitoring according to two different warning criteria for 6 months after intramedullary spinal ependymoma (IMSE) surgery.

MATERIAL AND METHODS

To evaluate the validity of intraoperative somatosensory-evoked potential (SSEP) and motor-evoked potential (MEP) monitoring according to two different warning criteria for 6 months after intramedullary spinal ependymoma (IMSE) surgery.

RESULTS

The success rates of SSEP and MEP monitoring were 84.9% and 83.7%, respectively. There was one indeterminate case in SSEP and six in MEP. All-or-none criterion in SSEP and MEP monitoring showed higher specificity, PPV, and DOR than 50% decline criterion during 6 months. During the follow up, 37 of 38 extremities (97.4%) and 21 of 29 extremities (72.4%) were observed the improvement of sensory and motor deficit, respectively. Seven indeterminate cases also showed good clinical outcomes. However, most patients remained some degree of neurologic deficit.

CONCLUSION

Many false positive and false negative results of SSEP and MEP monitoring occurred immediately postoperative period. All-or-none criterion was more beneficial for IMSE surgery than 50% decline criterion. This trend was maintained until 6 months after surgery.

How Cancer Patients Reported Their Quality of Life? Findings From a Nationwide Cross-Sectional Survey in Korea

Background: Cancer treatments have negative physical and socio-emotional consequences. Understanding which problems cancer patients are suffering and their quality of life (QOL) status is therefore important. Aim: This study aimed to describe how cancer patients reported their QOL and factors associated therewith. Methods: A total of 689 cancer patients aged ≥ 19 were selected from the Korea National and Nutrition Examination Survey (KNHANES), 2007-2015. HRQOL was measured using the five dimensions and summary index (ranges from 0 to 1) of the EuroQOL-5 (EQ-5D). Higher index score and less problems reported in dimensions indicates better QOL status. Logistic regression was performed to analyze the probability of cancer patient reporting problem in QOL dimensions. Statistical analyses were adjusted for sample weights. Result: Of 689 participants, mean age was 57.7 ± 0.67, 47.9% were male, 80.4% lived in urban area. 29.3% had hypertension and 15.3% had arthritis as comorbidity. Mean EQ-5D index score was 0.898 ± 0.007; higher score was noted in 19-65 age group (0.932 ± 0.007), living in urban area (0.906 ± 0.008), living in apartment (0.926 ± 0.008), male gender (0.912 ± 0.011), higher income, higher education level and more comorbidities ( P < 0.05). Participants reported more problems in pain or discomfort (34.09%), followed by mobility (24.91%) and usual activities (19.72%). Less problems were recorded in depression (17.37%) and self-care (8.04%). Patients with two or more comorbidities experienced higher chance of reporting problems in mobility, usual activity and self-care (aOR 4.01, 3.11 and 2.82 respectively, P < 0.05). Older age group was associated with higher chance of reporting problems in all QOL dimensions. Female cancer patients experienced higher chance of reporting problems in pain/discomfort and depression/anxiety (aOR 2.11 and 2.18 respectively, P < 0.05). Conclusion: More than one third of Korean adult cancer patients reported moderate or severe level of pain and discomfort. Older age, female gender and having two or more comorbidities were factors associated with lower QOL.

Integrating 3D Rotational Angiography into Gamma Knife Planning

3D rotational angiography provides remarkable spatial resolution for cerebrovascular disorders; however, it cannot be integrated directly into gamma knife planning due to the discrepancy of DICOM "tag" information, and most physicians still cannot benefit from 3D rotational angiography. Here, we describe a simple and easy technique to enable the integration of 3D rotational angiography.

Early Vs Late Liver Retransplantation: Different Characteristics and Prognostic Factors

BACKGROUND

East Asia is a known endemic area for hepatitis B, and living donor liver transplantation is mainly performed. Liver retransplantation (ReLT) is expected to become an increasing problem because of a shortage of organs. This study aimed to compare early and late ReLT with consideration of specific circumstances and disease background of East Asians.

METHODS

Between October 1996 and January 2015, 51 patients underwent ReLT; we performed a retrospective analysis of data obtained from medical records of the patients. Clinical characteristics, indication, causes of death, survival rate, and prognostic factors were investigated.

RESULT

The survival rate for early ReLT (n = 18) was 51.5% and that for late ReLT (n = 33) was 50.1% at 1 year postoperatively. Continuous venovenous hemodialysis and the use of mechanical ventilators were more frequent, and pre-retransplant intensive care unit stay and prothrombin time was longer in early ReLT than in late ReLT. Operation time was longer and the amount of intraoperative blood loss was greater in late ReLT than in early ReLT. Multivariate analysis showed that a higher C-reactive protein level increased mortality in early ReLT (P = .045), whereas a higher total bilirubin level increased the risk of death in late ReLT (P = .03).

CONCLUSION

Patients with early ReLT are likely to be sicker pre-retransplantation and require adequate treatment of the pretransplant infectious disease. On the other hand, late ReLT is likely to be technically more difficult and should be decided before the total bilirubin level increases substantially.

MMP20 Overexpression Disrupts Molar Ameloblast Polarity and Migration

Ameloblasts responsible for enamel formation express matrix metalloproteinase 20 (MMP20), an enzyme that cleaves enamel matrix proteins, including amelogenin (AMELX) and ameloblastin (AMBN). Previously, we showed that continuously erupting incisors from transgenic mice overexpressing active MMP20 had a massive cell infiltrate present within their enamel space, leading to enamel mineralization defects. However, effects of MMP20 overexpression on mouse molars were not analyzed, although these teeth more accurately represent human odontogenesis. Therefore, MMP20-overexpressing mice ( Mmp20^+/+Tg⁺) were assessed by multiscale analyses, combining several approaches from high-resolution micro-computed tomography to enamel organ immunoblots. During the secretory stage at postnatal day 6 (P6), Mmp20^+/+Tg⁺ mice had a discontinuous ameloblast layer and, unlike incisors, molar P12 maturation stage ameloblasts abnormally migrated away from the enamel layer into the stratum intermedium/stellate reticulum. TOPflash assays performed in vitro demonstrated that MMP20 expression promoted β-catenin nuclear localization and that MMP20 expression promoted invasion through Matrigel-coated filters. However, for both assays, significant differences were eliminated in the presence of the β-catenin inhibitor ICG-001. This suggests that MMP20 activity promotes cell migration via the Wnt pathway. In vivo, the unique molar migration of amelogenin-expressing ameloblasts was associated with abnormal deposition of ectopic calcified nodules surrounding the adherent enamel layer. Enamel content was assessed just prior to eruption at P15. Compared to wild-type, Mmp20^+/+Tg⁺ molars exhibited significant reductions in enamel thickness (70%), volume (60%), and mineral density (40%), and MMP20 overexpression resulted in premature cleavage of AMBN, which likely contributed to the severe defects in enamel mineralization. In addition, Mmp20^+/+Tg⁺ mouse molar enamel organs had increased levels of inactive p-cofilin, a protein that regulates cell polarity. These data demonstrate that increased MMP20 activity in molars causes premature degradation of ameloblastin and inactivation of cofilin, which may contribute to pathological Wnt-mediated cell migration away from the enamel layer.

Fluoride affects enamel protein content via TGF-β1-mediated KLK4 inhibition

Dental fluorosis is caused by chronic high-level fluoride (F(-)) exposure during enamel development, and fluorosed enamel has a higher than normal protein content. Matrix metalloproteinase 20 cleaves enamel matrix proteins during the secretory stage, and KLK4 further cleaves these proteins during the maturation stage so that the proteins can be reabsorbed from the hardening enamel. We show that transforming growth factor β1 (TGF-β1) can induce Klk4 expression, and we examine the effect of F(-) on TGF-β1 and KLK4 expression. We found that in vivo F(-) inhibits Klk4 but not Mmp20 transcript levels. LacZ-C57BL/6-Klk4 (+/LacZ) mice have LacZ inserted in frame at the Klk4 translation initiation site so that the endogenous Klk4 promoter drives LacZ expression in the same temporal/spatial way as it does for Klk4. KLK4 protein levels in rat enamel and β-galactosidase staining in LacZ-C57BL/6-Klk4 (+/LacZ) mouse enamel were both significantly reduced by F(-) treatment. Since TGF-β1 induces KLK4 expression, we tested and found that F(-) significantly reduced Tgf-β1 transcript levels in rat enamel organ. These data suggest that F(-)-mediated downregulation of TGF-β1 expression contributes to reduced KLK4 protein levels in fluorosed enamel and provides an explanation for why fluorosed enamel has a higher than normal protein content.

Surface Reconstruction during Molecular Beam Epitaxial Growth of GaN (0001)

Surface reconstructions during homoepitaxial growth of GaN (0001) are studied using reflection high-energy electron diffraction and scanning tunneling microscopy. In agreement with previous workers, a distinct transition from rough to smooth morphology is seen as a function of Ga to N ratio during growth. However, in contrast to some prior reports, no evidence for a 2×2 reconstruction during GaN growth is observed. Observations have been made using four different nitrogen plasma sources, with similar results in each case. A 2×2 structure of the surface can be obtained, but only during nitridation of the surface in the absence of a Ga flux.

Schottky Diodes on MOCVD Grown AlGaN Films

Au Schottky diodes were prepared by vacuum evaporation or by plasma sputtering on n-AlGaN(Si) films with Al mole fractions of 0, 0.11 or 0.23. The barrier heights were deduced from C-V and I-T measurements. The difference between the C-V and I-T results was less than 0.1 eV for the barriers deposited at 300 °C on HF etched samles with prior in situ heating at 450 °C. For low deposition temperatures (about 150°C) C-V and I-T methods give results differing by some tenths of an eV. For deposition temperatures exceeding 450°C the diodes were very leaky. The barrier heights were 0.8 eV, 0. 9 eV and 1.1 eV for AlGaN with compositions of 0, 0.11 and 0.23. For plasma sputtered diodes on GaN and AlGaN (x=0.11) samples, the difference in C-V and I-T results was quite considerable and admittance spectroscopy indicated the presence of deep electron traps at 0.12-0.14 eV that were absent in vacuum evaporated diodes. For similar diodes on AlGaN(x=0.23) samples the results of C-V and I-T measurements were very close and no traps at 0.12-0.14 eV could be detected. This difference is most likely due to damage caused by low energy ions. More Al-rich films are less susceptible to such damage. Persistent photocapacitance was observed in n-AlGaN Schottky diodes after illumination at 85K.

Importance of donor-recipient age gradient to the prediction of graft outcome after living donor liver transplantation

PURPOSE

Advanced donor age is a well-known risk factor for poor graft function after living donor liver transplantation (LDLT). In addition, advanced recipient age has a significant impact because of the high prevalence of comorbidities. We investigated the relationship between donor-recipient age gradient (DRAG) and the posttransplant outcomes in LDLT.

METHODS

We included 821 consecutive adult recipients who underwent LDLT from June 1997 to May 2011. According to the value of DRAG, they were divided into 2 groups: Negative years (the donor was younger than the recipient) and positive years (the donor was older than the recipient). These groups were further divided into subgroups (≤-21, -20 to -1, 0 to 20, and ≥21 years). We collected retrospectively patient characteristics, laboratory results, medical and surgical complications, and graft loss.

RESULTS

The positive DRAG group had higher level of posttransplant alkaline phosphatase, but a lower incidence of biliary complications. The negative DRAG group, particularly DRAG ≤ -21 years was associated with the superior 1-, 3-, 5-, and 10-year graft survivals. Recipients with DRAG ≥ 21 showed persistently inferior graft survival during the observation period. In cases of young donors, transplants utilizing lower DRAG seen between young donors and older recipients showed more favorable graft survival than that of young-to-young transplants.

CONCLUSION

This study demonstrated that DRAG and a fixed donor age limit could be significant factors to predict graft survival after LDLT. Patients should carefully consider the worse graft survival if the donor is older than the recipient by ≥20.

Comparison between resection and transplantation in combined hepatocellular and cholangiocarcinoma

OBJECTIVE

The treatment of choice for combined hepatocellular and cholangiocarcinoma (cHCC-CC) is surgical resection. However, the efficacy of liver transplantation is not clear. We compared the surgical outcome of hepatic resection and liver transplantation for cHCC-CC.

PATIENTS AND METHODS

From 1995 to 2012, 89 patients were diagnosed with cHCC-CC after hepatic resection and 8 patients diagnosed with cHCC-CC after liver transplantation. We excluded 21 patients who were American Joint Committee on Cancer Staging Stage III or IV and lost to follow-up. The outcomes were reviewed retrospectively.

RESULTS

The poor prognostic factors in cHCC-CC patients who underwent hepatectomy were large tumor size (>5 cm), small safety margin (<2 cm), and low preoperative albumin level. The disease-free survival (DFS) and overall survival (OS) between the hepatectomy group (n = 68) and the liver transplant group (n = 8) was not statistically different (5-year DFS: 26.2% vs 37.5%, P = .333; 5-year OS: 42.1% vs 50%, P = .591). In the small tumor subgroup (tumor size <5 cm), the DFS and OS between the 2 surgical procedures was not different, and in the adequate resection margin subgroup (safety margin >2 cm), survival was comparable.

CONCLUSIONS

In well-selected cases with small tumor size and with preserved liver function, liver resection should be considered when complete resection is possible.

Effects of Rashba and Dresselhaus spin-orbit interactions on the ground state of two-dimensional localized spins

Starting with the indirect exchange model influenced by the Rashba and the Dresselhaus spin-orbit interactions, we derive the Dzyaloshinskii-Moriya interaction of localized spins. The strength of the Dzyaloshinskii-Moriya interaction is compared with that of the Heisenberg exchange term as a function of atomic distance. Using the calculated interaction strengths, we discuss the formation of various atomic ground states as a function of temperature and external magnetic field. By plotting the magnetic field-temperature phase diagram, we present approximate phase boundaries between the spiral, Skyrmion and ferromagnetic states of the two-dimensional weak ferromagnetic system.

Outbreak among healthy newborns due to a new variant of USA300-related meticillin-resistant Staphylococcus aureus

BACKGROUND

The prevalence of community-associated meticillin-resistant Staphylococcus aureus (CA-MRSA) is increasing throughout the world and is an important cause of skin and soft tissue infection (SSTI) in children and neonates.

AIM

To describe the successful control of an outbreak caused by a new strain of CA-MRSA in a newborn nursery.

METHODS

The investigation of the outbreak in July 2012 is reported with the control measures taken. Molecular typing of the MRSA isolates was performed.

FINDINGS

An outbreak of SSTI caused by CA-MRSA occurred in a newborn nursery. Six neonates were infected in a one-month period [infection rate: 8.5% (6/71)]. A new variant of CA-MRSA was responsible, which was characterized as USA300-related, Panton-Valentine Leucocidin (PVL) positive, arginine catabolic mobile element (ACME) negative, sequence type 8 (ST8), staphylococcal cassette chromosome mec (SCCmec) type IVa, agr type I and spa type t008. The outbreak among term neonates followed a rapid transmission pattern and was successfully controlled by implementing various outbreak control measures, including universal chlorhexidine bathing.

CONCLUSION

This is the first report of a hospital outbreak caused by a USA300-related CA-MRSA clone in Korea. Early recognition and reinforcement of infection control measures are important in decreasing transmission of CA-MRSA in a hospital setting.

Regulation of the mitogen-activated protein kinase kinase (MEK)-1 by NAD(+)-dependent deacetylases

Sirtuins are class III deacetylases that regulate many essential processes, including cellular stress, genome stability, and metabolism. Although these NAD⁺-dependent deacetylases control adaptive cellular responses, identification of sirtuin-regulated signaling targets remain under-studied. Here, we demonstrate that acetylation of the mitogen-activated protein kinase kinase-1 (MEK1) stimulates its kinase activity, and that acetylated MEK1 is under the regulatory control of the sirtuin family members SIRT1 and SIRT2. Treatment of cells with sirtuin inhibitors, or siRNA knockdown of SIRT1 or SIRT2 proteins, increases MEK1 acetylation and subsequent phosphorylation of the extracellular signal-regulated kinase (ERK). Generation of an acetyl-specific MEK1 antibody demonstrates that endogenous acetylated MEK1 is extensively enriched in the nucleus following epidermal growth factor (EGF) stimulation. An acetyl-mimic of MEK1 increases inappropriate growth properties, suggesting that acetylation of MEK1 has oncogenic potential.

Optimal device and method for transportation of isolated porcine islet

INTRODUCTION

We investigated the optimal method for transportation of isolated porcine islets from an isolation facility to a transplant hospital or research center in terms of temperature, oxygen supply, and shaking effect.

METHODS

Commercially available insulator boxes with thermoregulators exposed for 5 hours under two external temperatures (4°C and 37°C) were monitored using HOBO temperature loggers. To find the optimal transport device, we compared islet counts, viability, quality, and function in conical tubes, gas-permeable bags (GPB) and gas-permeable flasks (GPF) after 1, 3 and 5 hours. To evaluate the effects of shaking on islets, we also analyzed the difference between a control and a shaking group in each device with time.

RESULTS

Commercially available Styrofoam insulators with thermoregulators maintained the internal temperature near the target. Islet recovery rate for GPF, which was higher than other devices, was maintained, while those decreased with time for conical tube and GPB containers adenosine diphosphate/adenosine triphosphate (ADP/ATP) ratio for GPF was lower than other devices, albeit not significantly fluoroscein acrimide/propidium iodide (AO/PI) ratio for GPF was higher than other devices after 5 hours. Glucose stimulated index was not different among the devices. In comparison with the control group, shaking yielded comparable islet survival, viability and function.

CONCLUSION

Our study demonstrated that the use of commercially available insulator boxes with thermoregulators maintained internal temperature close to the target value and that GPF was more favorable for islet oxygenation during transportation. This study also suggested negligible impact of shaking on isolated porcine islets during transportation.