Search for Boosted Dark Matter in COSINE-100.

We search for energetic electron recoil signals induced by boosted dark matter (BDM) from the galactic center using the COSINE-100 array of NaI(Tl) crystal detectors at the Yangyang Underground Laboratory. The signal would be an excess of events with energies above 4 MeV over the well-understood background. Because no excess of events are observed in a 97.7 kg·yr exposure, we set limits on BDM interactions under a variety of hypotheses. Notably, we explored the dark photon parameter space, leading to competitive limits compared to direct dark photon search experiments, particularly for dark photon masses below 4 MeV and considering the invisible decay mode. Furthermore, by comparing our results with a previous BDM search conducted by the Super-Kamionkande experiment, we found that the COSINE-100 detector has advantages in searching for low-mass dark matter. This analysis demonstrates the potential of the COSINE-100 detector to search for MeV electron recoil signals produced by the dark sector particle interactions.

Patterns of Regional Failure after Pancreaticoduodenectomy in Patients with Distal Extrahepatic Cholangiocarcinoma: Suggestion of the Clinical Target Volume for Elective Nodal Irradiation.

AIMS: To evaluate the pattern of locoregional recurrence (LRR) after pancreaticoduodenectomy in patients with distal extrahepatic cholangiocarcinoma (DEHC) and to identify an optimal target volume for elective nodal irradiation. MATERIALS AND METHODS: We analysed the medical records of DEHC patients who underwent pancreaticoduodenectomy and had LRR between 1991 and 2015. Among these patients, 30 received adjuvant chemotherapy alone, 14 underwent radiotherapy with or without chemotherapy and 28 received no treatment. After reviewing computed tomography or magnetic resonance imaging scans, the sites of LRR were identified and mapped to the corresponding locations on the representative computed tomography images. RESULTS: In total, 136 LRRs were identified in 72 patients from four institutions. Local recurrences were observed at 44 sites (32.4%): tumour bed in 15, choledochojejunostomy in 25 and pancreaticojejunostomy in four. Regional recurrences were observed at 92 sites (67.6%); the most common site was the portal vein area (n = 18), followed by the para-aortic area (n = 17). Based on the mapped plots of regional recurrence, a clinical target volume covering 90% of regional recurrences was generated using the appropriate margin for the vascular structures of the portal vein, celiac axis, superior mesenteric artery, left gastric artery and aorta. CONCLUSIONS: Given the pattern of LRR, we showed that the nodal clinical target volume based on vascular structures could appropriately cover high-risk regions of nodal involvement. These findings may help physicians construct a target volume in postoperative radiotherapy for DEHC patients undergoing pancreaticoduodenectomy.

Comparison of outcomes of treatment for ranula: a proportion meta-analysis.

Treatment for ranula is classified into three categories depending on how the leaking saliva is managed: removal of the leaking site by intraoral or transcervical resection of the sublingual gland; formation of a drainage tract through the wall of the pseudocyst by micromarsupialisation or marsupialisation; or sealing of the site of the leak by inducing fibrosis with a sclerosing agent. Resection of the sublingual gland is probably the option most likely to be curative for both oral and plunging ranula considering their pathophysiology. Although alternative treatments have been introduced to avoid the invasiveness of resection of the gland, their outcomes have been inconsistent. The objective of this study therefore was to help decision-making by providing more integrated rates of cure, consistency of treatment, and morbidity, depending on types of treatment used in previous series of cases. We used proportion meta-analysis of 39 such published series, and the most curative treatment for oral ranula was intraoral resection of the sublingual gland. Micromarsupialisation and its modification showed cure rates comparable with those of resection of the gland, but these were moderately inconsistent. In the treatment of plunging ranula, there was no significant difference in cure rate between the intraoral and transcervical approaches, although they both showed higher cure rates than injection of OK-432. Comparisons of morbidity were available for patients who had developed nerve dysfunction and haematoma after the intraoral and transcervical approaches and there was no significant difference between the two, though the morbidity was higher after the transcervical than that after the intraoral approach. In conclusion, intraoral resection of the sublingual gland is sufficient treatment with a tendency to have fewer complications than that in the transcervical approach.

Efficacy and safety of transarterial chemoembolisation with cone-beam CT in patients with hepatocellular carcinoma within the Milan criteria: a retrospective cohort study.

AIM: To compare the therapeutic efficacy and safety of transarterial chemoembolisation (TACE) for hepatocellular carcinoma (HCC) within the Milan criteria with or without the use of cone-beam computed tomography (CBCT). MATERIALS AND METHODS: Patients with HCC within the Milan criteria who underwent conventional angiography-guided TACE (Angio-TACE group: 58 patients from January 2010 to December 2011) were compared with those who underwent CBCT-guided TACE (CBCT-TACE group: 55 patients from January 2013 to December 2014). Local progression-free survival (LPFS), progression-free survival (PFS), and overall survival (OS) were compared. Adverse events after TACE were also investigated. RESULTS: Baseline characteristics were balanced between the two groups. LPFS was significantly longer in the CBCT-TACE group than in the Angio-TACE group (median: not reached for 36 versus 19.2 months, respectively; Log-rank p=0.029). In multivariable Cox regression analysis, CBCT guidance had a significantly lower risk of local progression or death (adjusted hazard ratio: 0.585; 95% confidence interval, 0.344-0.995; p=0.048); however, there was no significant difference in PFS (3-year PFS: 15.9% versus 26.8%, respectively; p=0.122) or OS (3-year OS: 85% versus 88.2%, respectively; p=0.761) between the Angio-TACE and CBCT-TACE groups. Post-embolisation syndrome occurred significantly less frequently in the CBCT-TACE group (p=0.002). CONCLUSION: CBCT-guided TACE could improve local tumour control for HCC within Milan criteria and showed fewer cases of post-embolisation syndrome.

Background model for the NaI(Tl) crystals in COSINE-100.

The COSINE-100 dark matter search experiment is an array of NaI(Tl) crystal detectors located in the Yangyang Underground Laboratory (Y2L). To understand measured backgrounds in the NaI(Tl) crystals we have performed Monte Carlo simulations using the Geant4 toolkit and developed background models for each crystal that consider contributions from both internal and external sources, including cosmogenic nuclides. The background models are based on comparisons of measurement data with Monte Carlo simulations that are guided by a campaign of material assays and are used to evaluate backgrounds and identify their sources. The average background level for the six crystals (70 kg total mass) that are studied is 3.5 counts/day/keV/kg in the (2-6) keV energy interval. The dominant contributors in this energy region are found to be 210 Pb and 3 H.

Risk of diabetes in viral hepatitis B or C patients compared to that in noninfected individuals in Korea, 2002-2013: A population-based cohort study.

While the association between hepatitis C virus (HCV) infection and diabetes has been established, the relationship between hepatitis B virus (HBV) infection and diabetes remains unclear. Therefore, we compared the association between diabetes development in HBV, HCV and co-infected (HBV/HCV) patients to that in noninfected participants using population-based cohort data. We used the National Health Insurance Service-National Sample Cohort, which consists of 514 791 randomly selected persons among those who underwent health check-ups from 2002 to 2003 aged 40-79 years. Adults found to have HBV or HCV infection from 2002 to 2003, without a prior history of diabetes, were selected as subjects. Competing risk regression models were used to estimate cumulative incidence and hazards ratios (HRs) of diabetes development. The cumulative incidences, incidence densities and HRs of diabetes were highest in the co-infected group, followed by those in the HCV-, HBV- and noninfected groups. The 12-year cumulative incidences were as follows: 42.0% in HBV/HCV-, 32.9% in HCV-, 23.9% in HBV- and 18.3% in the noninfected groups. The incidence density per 1000 person-years was 55.0, 51.5, 38.2 and 28.2 for the HBV/HCV-, HCV-, HBV- and noninfected groups, respectively. The adjusted HRs for diabetes were 1.90, 1.68 and 1.41 for the HBV/HCV-, HCV- and HBV-infected groups, respectively. Our findings suggest that both HCV and HBV infections are associated with the development of diabetes; therefore, prevention of, screening for, and treatment of both may reduce the risk of diabetes in these patients.

Prognostic relevance of lymph node status for patients with ampullary adenocarcinoma after radical resection followed by adjuvant treatment.

PURPOSE: Attempts have been made to revise the nodal stage due to simplicity of current N staging system in ampullary adenocarcinoma. However, because of the disease rarity, there have only been a few studies assessing the prognostic impact of lymph node (LN) parameters. METHODS: We retrospectively analyzed 120 patients who underwent radical resection followed by adjuvant chemoradiotherapy for ampullary adenocarcinoma. The effect of LN parameters (number of total harvest LNs, number of metastatic LN (MLN), lymph node ratio (LNR), and log odds of positive LNs (LODDS)) on overall survival (OS), locoregional relapse-free survival (LRFS) and distant metastasis-free survival were evaluated. Cutoff points of MLN, LNR and LODDs were determined using maximal χ2 method. RESULTS: Fifty-seven patients (48%) were staged as pN1 and their survival was not significantly decreased compared with pN0 patients. There was also no significant difference between patients with MLN 0 vs. 1. In univariate analyses, MLN (0-1 vs. ≥2), LNR (≤17% vs. >17%) and perineural invasion were common prognosticators for OS and LRFS. Distant metastasis-free survival was not influenced by LN status. In addition, multivariate analysis revealed that among the LN parameters, LNR was able to independently predict both OS and LRFS. CONCLUSIONS: LNR performs better than other LN related parameters for predicting survival. After radical resection followed by adjuvant treatment, survival of patients with one positive LN does not seem to differ from patients without LN metastasis.

The impact of obesity on febrile urinary tract infection and renal scarring in children with vesicoureteral reflux.

INTRODUCTION: It has become clear that obesity is associated with a variety of infectious diseases, including urinary tract infection (UTI) and renal scarring. OBJECTIVE: The aim of this study was to evaluate the association between obesity and the degree of febrile UTI (fUTI) and renal scarring in children with vesicoureteral reflux (VUR), and to stratify the results into obesity subcategories. STUDY DESIGN: A total of 186 patients were diagnosed with VUR between January 2002 and December 2008. This study retrospectively reviewed the medical records of 72 children with primary VUR who had recurrent fUTI (more than twice). Overweight or obese status of the patients aged <2 years was defined using weight-for-length (WFL) measurements. For 2-5 year old children, body mass index (BMI) percentile-for-age was used. They were divided into three groups as follows; standard (<85%), overweight (85-95%), and obese (≥95%). The following clinical variables were compared: age at diagnosis of primary VUR (months), sex, VUR grade, hydronephrosis grade, presence of renal scarring, surgical treatment, and degree of inflammation during fUTI. RESULTS: In the overweight and obese groups, VUR was diagnosed at a young age (P = 0.05), the degree of renal scarring was more severe (P = 0.006), and serum white blood cell count, C-reactive protein, and erythrocyte sedimentation rate (ESR) levels were significantly higher (P < 0.001, P < 0.001, and P < 0.001, respectively). Abnormal focal dimercaptosuccinic acid (DMSA) defects were present in 25 of the 72 children (35%). Cortical defects occurred more frequently in children with obesity, and they were associated with a higher grade of reflux and serum ESR levels (P = 0.007, P = 0.042, and P = 0.021, respectively). Among these risk factors, high-grade VUR (OR = 9.93, 95% CI = 1.13-86.71), and being overweight and obese (OR = 5.26, 95% CI = 1.75-15.82) were associated with increased renal scarring. However, ESR was not associated with renal scarring (OR = 1.01, 95% CI = 0.95-1.07). DISCUSSION: The relationships between obesity and UTI are controversial. Some studies have shown positive results; however, other studies have shown opposite results. The main limitations of this study were the retrospective data collection via electronic medical records, and the small number of subjects. CONCLUSIONS: This study showed that obesity in patients with VUR has an effect on fUTI and renal scar formation. If the patients with VUR have obesity, close follow-up should be performed, and VUR patients should be started on a weight-loss program, which could reduce the number of patients with chronic kidney disease in the future.

Spin-orbit coupled molecular quantum magnetism realized in inorganic solid.

Molecular quantum magnetism involving an isolated spin state is of particular interest due to the characteristic quantum phenomena underlying spin qubits or molecular spintronics for quantum information devices, as demonstrated in magnetic metal-organic molecular systems, the so-called molecular magnets. Here we report the molecular quantum magnetism realized in an inorganic solid Ba3Yb2Zn5O11 with spin-orbit coupled pseudospin-½ Yb(3+) ions. The magnetization represents the magnetic quantum values of an isolated Yb4 tetrahedron with a total (pseudo)spin 0, 1 and 2. Inelastic neutron scattering results reveal that a large Dzyaloshinsky-Moriya interaction originating from strong spin-orbit coupling of Yb 4f is a key ingredient to explain magnetic excitations of the molecular magnet states. The Dzyaloshinsky-Moriya interaction allows a non-adiabatic quantum transition between avoided crossing energy levels, and also results in unexpected magnetic behaviours in conventional molecular magnets.

Facile Synthesis of Iron Oxide/Graphene Nanocomposites Using Liquid Phase Plasma Method.

Liquid phase plasma (LPP) method was applied, for the first time, to the impregnation of iron oxide nanoparticles onto graphene sheet. Iron oxide nanoparticles with the size of 50 nm were precipitated with uniform dispersion on the surface of graphene sheet. The amount of iron oxide nanoparticles precipitated on graphene sheets increased with increasing LPP process times. The XPS, Raman and EDX analyses showed that the iron oxide/graphene composites synthesized by the LPP process.

Application of Silver and Silver Oxide Nanoparticles Impregnated on Activated Carbon to the Degradation of Bromate.

Silver and silver oxide nanoparticles were impregnated on the surface of powdered activated carbon (PAC) using a single-step liquid phase plasma (LPP) method. Spherical silver and silver oxide nanoparticles of 20 to 100 nm size were dipersed evenly on the surface of PAC. The impregnated PAC exhibited a higher activity for the decomposition of bromate than bare PAC. The XPS, Raman and EDX analyses showed that the Ag/PAC composites synthesized by the LPP process.

First Observation of the Doubly Cabibbo-Suppressed Decay of a Charmed Baryon: Λ_{c}

We report the first observation of the decay Λ_{c}^{+}→pK^{+}π^{-} using a 980 fb^{-1} data sample collected by the Belle detector at the KEKB asymmetric-energy e^{+}e^{-} collider. This is the first observation of a doubly Cabibbo-suppressed decay of a charmed baryon. We measure the branching ratio of this decay with respect to its Cabibbo-favored counterpart to be B(Λ_{c}^{+}→pK^{+}π^{-})/B(Λ_{c}^{+}→pK^{-}π^{+})=(2.35±0.27±0.21)×10^{-3}, where the uncertainties are statistical and systematic, respectively.

Cardiorespiratory Fitness and Metabolic Syndrome in Postmenopausal African-American Women.

We examined the association of cardiorespiratory fitness with metabolic syndrome in overweight/obese postmenopausal African-American women. Pooled baseline data on 170 African-American women from 2 exercise trials were examined. Metabolic syndrome was defined as at least 3 of the following: abdominal obesity, glucose intolerance, hypertension, low high-density lipoprotein cholesterol (HDL-C), and high triglycerides. Cardiorespiratory fitness (VO2peak) was determined using the Bruce treadmill protocol and categorized as: Very Low (VLCRF<18 mL·kg(-1) min(-1)), Low (LCRF=18.0-220-22-22.0 mL·kg(-1) min(-1)), and Moderate (MCRF>22.0 mL·kg(-1) min(-1)). Associations of metabolic syndrome with cardiorespiratory fitness were analyzed using one-way ANOVA and linear regression. VO2peak was significantly lower in the VLCRF compared to the MCRF group. Lower cardiorespiratory fitness was associated with higher prevalence of metabolic syndrome, abdominal obesity, hypertriglyceridemia, and low HDL among overweight/obese postmenopausal African-American women. In fully adjusted models, higher waist circumference and triglycerides were associated with lower VO2peak levels (P<0.01) and higher HDL-C was associated with higher VO2peak levels (P=0.03). Overweight/obese postmenopausal African-American women with very low cardiorespiratory fitness are more likely to have metabolic syndrome, higher body mass index, and unhealthier levels of certain metabolic syndrome components than women with moderate cardiorespiratory fitness.

Accidental displacement of a dental implant into the submandibular space during explantation.

Dental implants are reliable and widely used, but complications such as peri-implantitis occasionally necessitate their removal. Accidents during removal are similar to those that may occur during extraction, including displacement into another structure in the maxillofacial region. We present a rare case of accidental displacement into the submandibular space, which happened during an attempt to remove an implant.

DNA methylation analysis for the diagnosis of thyroid nodules - a pilot study with reference to BRAF(V) (600E) mutation and cytopathology results.

OBJECTIVE: Promoter hypermethylation and the BRAF(V) (600E) mutation are both involved in thyroid tumorigenesis. We conducted a pilot study on the diagnosis of thyroid nodules by analysis of promoter hypermethylation status with reference to BRAF(V) (600E) mutation and cytopathology results using formalin-fixed, paraffin-embedded (FFPE) tissues and liquid-based preparation (LBP) thyroid fine needle aspiration (FNA) samples to predict more reliably the possibility of papillary carcinoma. METHODS: We initially performed MethyLight analysis for 30 genes that are known to be hypermethylated in malignancies using 164 papillary carcinomas and 77 benign tissue samples. Five genes selected from the tissue analysis were subsequently analysed in 75 surgically proven benign and 66 surgically proven papillary carcinoma LBP FNA samples. Samples that showed two or more positive results among the five genes were classified as methylation positive. We also analysed the BRAF(V) (600E) mutation status of the FNA samples. RESULTS: We identified five genes that were significantly hypermethylated in malignant tissues: PTGS2, HOXA1, TMEFF2, p16 and PTEN. With respect to diagnostic potential, results obtained using the BRAF(V) (600E) mutation test combined with cytological examination were not significantly different from those obtained with cytological examination only. Combining methylation analyses with cytological examination or performing all three tests for diagnoses did not improve significantly the negative predictive values and sensitivity, but a significant decrease in positive predictive value and specificity was observed. CONCLUSION: Further studies are needed on larger samples to assess the potential value of methylation analysis of thyroid FNA.

Altered serotonin transporter binding potential in patients with obsessive-compulsive disorder under escitalopram treatment: [11C]DASB PET study.

BACKGROUND: Obsessive-compulsive disorder (OCD) is a chronic, relapsing mental illness. Selective serotonin reuptake inhibitors block serotonin transporters (SERTs) and are the mainstay of treatment for OCD. SERT abnormalities are reported in drug-free patients with OCD, but it is not known what happens to SERT levels during treatment. This is important as alterations in SERT levels in patients under treatment could underlie poor response, or relapse during or after treatment. The aim of the present study was first to validate a novel approach to measuring SERT levels in people taking treatment and then to investigate SERT binding potential (BP) using [11C]DASB PET in patients with OCD currently treated with escitalopram in comparison with healthy controls. METHOD: Twelve patients and age- and sex-matched healthy controls were enrolled. The patients and healthy controls underwent serial PET scans after administration of escitalopram and blood samples for drug concentrations were collected simultaneously with the scans. Drug-free BPs were obtained by using an inhibitory E max model we developed previously. RESULTS: The inhibitory E max model was able to accurately predict drug-free SERT BP in people taking drug treatment. The drug-free BP in patients with OCD currently treated with escitalopram was significantly different from those in healthy volunteers [Cohen's d = 0.03 (caudate), 1.16 (putamen), 1.46 (thalamus), -5.67 (dorsal raphe nucleus)]. CONCLUSIONS: This result extends previous findings showing SERT abnormalities in drug-free patients with OCD by indicating that altered SERT availability is seen in OCD despite treatment. This could account for poor response and the high risk of relapse in OCD.

Population-based epidemiology of primary biliary cirrhosis in South Korea.

BACKGROUND: As a rare disease, only a few population-based epidemiology studies of primary biliary cirrhosis (PBC) have been reported. AIMS: To elucidate the nationwide prevalence, incidence, complications, fatality and direct medical costs of PBC in South Korea. METHODS: The nationwide Health Insurance Review and Assessment Service claims data and Rare Intractable Disease registration data on PBC, identified with the International Classification of Diseases (ICD) 10 code of K74.3, were obtained from 2009 to 2013. Age- and gender-specific prevalence and incidence rates of PBC were calculated, and data on complications, comorbidities, prescribed drugs, therapeutic procedures and direct medical costs were analysed. RESULTS: A total of 2824 patients over 20 years old with PBC were identified in 2009-2013 (female-to-male ratio 6.2, median age 57 years old). The average age- and sex-adjusted incidence from 2011 to 2013 was 8.57 per million per year, and the average age- and sex-adjusted prevalence from 2009 to 2013 was 47.50 per million population. About 10% of patients presented with complications such as ascites (10.3%), variceal bleeding (5.8%) and/or hepatocellular carcinoma (HCC) (1.3%). Liver transplantation was undertaken in 71 patients (2.5%) for 5 years. Case fatality was 2.2% and the transplantation-free survival was 95.4% for 5 years. CONCLUSIONS: This is the first report on the nationwide epidemiology of primary biliary cirrhosis in South Korea, demonstrating lower incidence and prevalence rates than those of Western countries, but a considerable disease burden, representing at least 10% were complicated with decompensated cirrhosis or hepatocellular carcinoma requiring liver transplantation.

Microporous carbon nanosheets with redox-active heteroatoms for pseudocapacitive charge storage.

We report microporous carbon nanosheets containing numerous redox active heteroatoms fabricated from exfoliated waste coffee grounds by simple heating with KOH for pseudocapacitive charge storage. We found that various heteroatom combinations in carbonaceous materials can be a redox host for lithium ion storage. The bio-inspired nanomaterials had unique characteristics, showing superior electrochemical performances as cathode for asymmetric pseudocapacitors.

Low pulmonary function is related with a high risk of sarcopenia in community-dwelling older adults: the Korea National Health and Nutrition Examination Survey (KNHANES) 2008-2011.

UNLABELLED: Sarcopenia is the age-related reduction of skeletal muscle mass in older individuals. Respiratory muscle strength may be related to skeletal muscle mass and, thus, the present study attempted to estimate the risk of sarcopenia relative to decreased pulmonary function. The present findings demonstrated that low pulmonary function was associated with low muscle mass in community-dwelling older adults. INTRODUCTION: Lean body mass is related to pulmonary function in patients with chronic obstructive pulmonary disease (COPD). However, the relationship between muscle mass and pulmonary function in healthy older adults has yet to be clarified. Thus, the present study investigated the association of pulmonary function with muscle mass in an older community-dwelling Korean population. METHODS: This study included 463 disease-free subjects over 65 years of age who underwent anthropometric measurements, laboratory tests, spirometry, and the estimation of appendicular skeletal muscle (ASM) mass in the 2008-2011 Korea National Health and Nutrition Examination Survey (KNHANES). Low muscle mass was defined as the value of ASM divided by height squared (ASM/height(2)) that was less than two standard deviations (SD) below the sex-specific mean of the young reference group. RESULTS: Forced expiratory volume in 1 s (FEV1[L]) and forced vital capacity (FVC[L]) were positively correlated with ASM/height(2) in males (p < 0.001 and p = 0.001, respectively) but not in females (p = 0.360 and p = 0.779, respectively). A univariate logistic regression analysis revealed that males with low FEV1 or FVC were more likely to have low muscle mass (odds ratio [OR] = 3.11, 95% confidence interval [CI] 1.62-5.99 for FEV1; OR = 1.99, 95% CI 1.13-3.53 for FVC); similar results were found for females, but the significance was lower (OR = 11.37, 95% CI 0.97-132.91 for FEV1; OR = 7.31, 95% CI 1.25-42.74 for FVC). After adjusting for age, smoking, and moderate physical activity, a low FEV1 value was associated with low muscle mass in both males (OR = 2.90, 95% CI 1.50-5.63) and females (OR = 9.15, 95% CI 1.53-54.77). CONCLUSIONS: Using nationally representative data from the 2008-2011 KNHANES, low pulmonary function was found to be associated with low muscle mass in community-dwelling older Korean adults.

Simultaneous determination of arbutin and its decomposed product hydroquinone in whitening creams using high-performance liquid chromatography with photodiode array detection: Effect of temperature and pH on decomposition.

OBJECTIVE: Arbutin is an effective agent for the treatment of melanin disorders. Arbutin may be converted to hydroquinone under conditions of high temperature, ultraviolet (UV) radiation and dilute acid. The aim of the current study was to develop an analytical method to determine the levels of arbutin and hydroquinone in whitening cosmetic products using high-performance liquid chromatography with photodiode array detection (HPLC-DAD). In addition, we investigated the effects of high temperature and pH on the decomposition of arbutin. METHODS: Samples extracted using two-step sonications were separated on a C18 column using a gradient mobile phase consisting of water and methanol. A 60-mm (40 µL) DAD cell was used to enhance the sensitivity of hydroquinone determination. Thermal decomposition of arbutin was evaluated at temperatures ranging from 60 to 120°C for 1-36 h. RESULTS: The method showed good linearity (R(2) ≥ 0.9997), precision (relative standard deviation, RSD < 5%) and acceptable extraction recovery (90-102.6%). The limits of quantitation for arbutin and hydroquinone were 0.0085 and 0.0119 µg mL(-1) , respectively. One sample of 21 cosmetic products tested contained arbutin at a concentration 1.61 g 100 g(-1) cream and 0.12 g 100 g(-1) cream of hydroquinone. Arbutin (327.18 ppm) decomposed after 6 h at 120°C and produced 10.73 ppm of hydroquinone. CONCLUSION: The developed method is simple to detect both arbutin and hydroquinone simultaneously in cosmetic products, at an adequate level of sensitivity. Notably, temperature and pH did not influence the decomposition of arbutin to hydroquinone in a 2% arbutin cream.