Preoperative Radiographic Simulation for Partial Uncinate Process Resection during Anterior Cervical Discectomy and Fusion to Achieve Adequate Foraminal Decompression and Prevention of Vertebral Artery Injury.

STUDY DESIGN: Retrospective radiographic study. PURPOSE: This study aims to demonstrate the proper resection trajectory of a partial posterior uncinate process resection combined with anterior cervical discectomy and fusion (ACDF) and evaluate whether foraminal stenosis or uncinate process degeneration increases the risk of vertebral artery (VA) injury. OVERVIEW OF LITERATURE: Appropriate resection trajectory that could result in sufficient decompression and avoid vertebral artery injury is yet unknown. METHODS: We retrospectively reviewed patients who underwent cervical magnetic resonance imaging and computed tomography angiography for preoperative ACDF evaluation. The segments were classified according to the presence of foraminal stenosis. The height, thickness, anteroposterior length, horizontal distance from the uncinate process to the VA, and vertical distance from the uncinate process baseline to the VA of the uncinate process were measured. The distance between the uncinate anterior margin and the resection trajectory (UAM-to-RT) was measured. RESULTS: There were no VA injuries or root injuries among the 101 patients who underwent ACDF (163 segments, mean age of 56.3±12.2). Uncinate anteroposterior length was considerably longer in foramens with foraminal stenosis, whereas uncinate process height, thickness, and distance between the uncinate process and VA were not significantly associated with foraminal stenosis. There were no significant differences in radiographic parameters based on uncinate degeneration. The UAM-to-RT distances for adequate decompression were 1.6±1.4 mm (range, 0-4.8 mm), 3.4±1.7 mm (range, 0-7.1 mm), 4.0±1.7 mm (range, 0-9.0 mm), and 4.5±1.2 mm (range, 2.5-7.5 mm) for C3-C4, C4-C5, C5-C6, and C6-C7, respectively. CONCLUSIONS: More than half of the uncinate process in the anteroposterior plane should be removed for adequate neural foramen decompression. Foraminal stenosis or uncinate degeneration did not alter the relative anatomy of the uncinate process and the VA and did not impact VA injury risk.

Evaluation and Monitoring of the Natural Toxin Ptaquiloside in Bracken Fern, Meat, and Dairy Products.

Ptaquiloside, a naturally occurring cancer-causing substance in bracken fern, has been detected in the meat and milk of cows fed a diet containing bracken fern. A rapid and sensitive method for the quantitative analysis of ptaquiloside in bracken fern, meat, and dairy products was developed using the QuEChERS method and liquid chromatography-tandem mass spectrometry. The method was validated according to the Association of Official Analytical Chemists guidelines and met the criteria. A single matrix-matched calibration method with bracken fern has been proposed, which is a novel strategy that uses one calibration for multiple matrices. The calibration curve ranged from 0.1 to 50 µg/kg and showed good linearity (r2 > 0.99). The limits of detection and quantification were 0.03 and 0.09 µg/kg, respectively. The intraday and interday accuracies were 83.5-98.5%, and the precision was <9.0%. This method was used for the monitoring and exposure assessment of ptaquiloside in all routes of exposure. A total of 0.1 µg/kg of ptaquiloside was detected in free-range beef, and the daily dietary exposure of South Koreans to ptaquiloside was estimated at up to 3.0 × 10-5 µg/kg b.w./day. The significance of this study is to evaluate commercially available products in which ptaquiloside may be present, to monitor consumer safety.

Factors related to the success of smoking cessation: A retrospective cohort study in Korea.

INTRODUCTION: Every year, at least half of the smokers in South Korea attempt to quit smoking. However, the Korean smoking rate remains still high among OECD countries. This study aimed to identify the factors that influence the success of smoking cessation efforts. METHODS: The study included 1395 smokers, who participated in a 12-week program comprising doctor counseling and pharmacological treatment (i.e. varenicline), conducted at smoking cessation clinics in two general hospitals from 2015 to 2019. The participants responded to a survey questionnaire inquiring about their smoking behaviors at the first visit to the clinic. After completing the program, they were asked whether they succeeded in smoking cessation. Based on participants' reported success or failure, multivariable logistic regression analyses were conducted to obtain adjusted odds ratios (AORs) and 95% confidence intervals (CIs) for factors related to smoking cessation success. RESULTS: Following the 12-week program, 39.6% of the participants (n=553) succeeded in smoking cessation. Lower rates of nicotine dependence (AOR=0.73; 95% Cl: 0.54-0.98) and lower total amounts of smoking (AOR=0.67; 95% Cl: 0.47-0.95) were significantly associated with higher success rates in smoking cessation. In addition, smokers who participated in the program for at least 8 weeks (AOR=7.16; 95% Cl: 5.57-9.20) and smokers who had hypertension (AOR=1.40; 95% Cl: 1.07-1.85) or a cardiovascular disease (AOR=1.68; 95% Cl: 1.03-2.75) achieved higher success rates. CONCLUSIONS: Smokers' success in smoking cessation was influenced by the period of visits to the smoking cessation clinic, the severity of nicotine dependence, and the presence of a cardiovascular disease including hypertension. Using these factors, smoking cessation strategy may be improved and personalized for individuals.

The relationship between smoking cigarettes and metabolic syndrome: A cross-sectional study with non-single residents of Seoul under 40 years old.

INTRODUCTION: Young adults receive health screenings at lower rates than other age groups, and it may be difficult to detect diseases in the early stages for this group. We examined differences in health status relative to smoking in a young age group using the results of health screenings conducted in engaged and newly married couples in a cross-sectional database. METHODS: The participants in this study were 808 young adults who visited a municipal hospital health screening center from July 2017 to March 2019. They completed a self-administered questionnaire, and physical measurements and a blood test were taken. They were classified into non-cigarette smokers, past cigarette smokers, and current cigarette smokers according to smoking behavior. In this study, we compared metabolic syndrome, the main components of which include obesity, high blood pressure, high blood triglycerides, low levels of HDL cholesterol and insulin resistance, with smoking behavior. RESULTS: The mean age of the participants was 30.9±3.3 years (males 32.0±3.2, females 29.8±3.1), and 13.9% were current cigarette smokers (males 22.8%, females 5.1%). The proportion of men in their 30s was 76.6% for male group and 50.0% for female group, indicating that the male group had a relatively higher proportion of older and current smokers. Significant differences were found in age, sex, blood pressure, metabolic abnormalities, and drinking status according to smoking status. Cigarette smokers had a 2.4-fold greater risk of metabolic syndrome (95% confidence interval [CI], 1.43-3.96) than non-cigarette smokers; in particular, they had a 2.6-fold (95% CI, 1.44-4.55) greater risk of hypertriglyceridemia and a three-fold (95% CI, 1.45-6.35) greater risk of low HDL cholesterol. CONCLUSIONS: In comparison with non-single, young and generally healthy city dwellers, the risk of metabolic syndrome was significantly higher in smokers than in non-smokers, and in particular, it was confirmed that the risk of hypertriglyceridemia and low HDL cholesterolemia was higher. Smoking cessation is necessary, even for the young, because smoking may cause changes in blood lipids even if the smoking duration is short.

Fluoride-assisted liquid chromatography-tandem mass spectrometry method for simultaneous analysis of propofol and its metabolites without derivatization in urine.

The misuse of propofol for recreational purposes has become a serious social issue. Accordingly, practical and sensitive analytical methods to investigate the chronic abuse and toxicity of propofol are required. However, current propofol determination methods using liquid chromatography-mass spectrometry (LC-MS/MS) suffer from problems associated with loss in sample preparation due to its volatility and its poor ionization efficiency and collision-induced dissociation in mass spectrometry. Herein, we have developed a sensitive and accurate fluoride-assisted LC-MS/MS method combined with direct-injection for propofol determination. Ionization via fluoride-ion attachment/induced deprotonation, effected by ammonium fluoride in the mobile phase, was found to dramatically improve the sensitivity of propofol without derivatization. Furthermore, direct injection without derivatization enables the simultaneous analysis of propofol and its phase II metabolites without analyte loss. The optimal concentration of ammonium fluoride in the mobile phase was found to be 1 mM under methanol conditions. The linearity is good (R2 ≥ 0.999) and the intra- and inter-day precisions for propofol determination are between 1.9 and 8.7%. The accuracies range from 87.5% to 105.4% and the limits of detection and quantitation for propofol in urine are 0.15 and 0.44 ng mL-1, respectively. The present method was successfully applied to human urine and showed a sufficient sensitivity to determine propofol and five phase II metabolites over 48 h in human urine after administration. Consequently, the fluoride-assisted LC-MS/MS method was demonstrated to be sensitive, accurate, and practical for the determination of propofol and its metabolites.

Segmental Height Decrease Adversely Affects Foraminal Height and Cervical Lordosis, But Not Clinical Outcome After Anterior Cervical Discectomy and Fusion Using Allografts.

OBJECTIVE: This study was conducted to elucidate the clinical significance of postoperative segmental height decrease (SHD) in anterior cervical discectomy and fusion (ACDF) using allografts. METHODS: We reviewed 88 patients who underwent ACDF using allografts as interbody spacers. Cervical lordosis, segmental lordosis, segmental height, foraminal height, fusion, allograft fracture, and resorption were assessed. Significant SHD was defined as that ≥2 mm. Neck pain visual analog scale (VAS) score, arm pain VAS score, and Neck Disability Index (NDI) score were also recorded. Significant segmental height decreased (SH-D) segments were compared with segmental height maintained (SH-M) segments. RESULTS: Thirty-two patients (36.4%) and 34 segments (23.1%) demonstrated significant SHD. SH-D segments demonstrated significantly lower segmental lordosis (3.7 ± 4.1 vs. 0.9 ± 4.8°; P < 0.01), foraminal height (9.6 ± 1.1 vs. 8.7 ± 0.9 mm; P < 0.01), and fusion rate (88 [77.9%] vs. 20 [58.9%]; P = 0.04) than SH-M segments at the final follow-up, respectively. Furthermore, global lordosis was significantly lower in the SH-D group (18.3 ± 8.5 vs. 13.9 ± 8.9°, respectively; P = 0.02). However, neck and arm pain VAS scores and NDI score did not demonstrate a significant difference between patients with and without significant SHD. Logistic regression analysis demonstrated that higher allograft height (P = 0.03), greater allograft anteroposterior length (P = 0.04), and allograft resorption or fracture (P < 0.01) were associated with increased risk of significant SHD. Logistic regression analysis also demonstrated that allograft resorption or fracture (P < 0.01) was associated with risk of nonunion. CONCLUSIONS: Significant SHD was associated with decreased segmental lordosis, global cervical lordosis, and foraminal height. However, significant SHD did not result in worsening of clinical symptoms. Larger allograft size was associated with risk of significant SHD. This study demonstrates provisional results that suggest allograft resorption or fracture may be a factor that adversely affects fusion or SHD.

The influence of hydrogen concentration in amorphous carbon films on mechanical properties and fluorine penetration: a density functional theory and ab initio molecular dynamics study.

Amorphous carbon (a-C) films have attracted significant attention due to their reliable structures and superior mechanical, chemical and electronic properties, making them a strong candidate as an etch hard mask material for the fabrication of future integrated semiconductor devices. Density functional theory (DFT) calculations and ab initio molecular dynamics (AIMD) simulations were performed to investigate the energetics, structure, and mechanical properties of the a-C films with an increasing sp3 content by adjusting the atomic density or hydrogen content. A drastic increase in the bulk modulus is observed by increasing the atomic density of the a-C films, which suggests that it would be difficult for the films hardened by high atomic density to relieve the stress of the individual layers within the overall stack in integrated semiconductor devices. However, the addition of hydrogen into the a-C films has little effect on increasing the bulk modulus even though the sp3 content increases. For the F blocking nature, the change in the sp3 content by both atomic density and H concentration makes the diffusion barrier against the F atom even higher and suppresses the F diffusion, indicating that the F atom would follow the diffusion path passing through the sp2 carbon and not the sp3 carbon due to the significantly high barrier. For the material design of a-C films with adequate doped characteristics, our results can provide a new straightforward strategy to tailor the a-C films with excellent mechanical and other novel physical and chemical properties.

Association between misalignment of circadian rhythm and obesity in Korean men: Sixth Korea National Health and Nutrition Examination Survey.

Background: The disruption of circadian rhythm has been found to associate with obesity in vivo and in vitro. Sleep duration, eating habits, total feeding time, and nightshift work can also affect circadian rhythms. This study investigated the association between misalignment of circadian rhythm and obesity in Korean men, using a cross-sectional database.Methods: This study used data from the Korean National Health and Nutrition Examination Survey (KNHANES), whose study population was 3,658 men aged 18 to 60 years. General and abdominal obesity was defined as a body mass index (BMI) ≥ 25 kg/m2 and waist circumference ≥ 90 cm, respectively. Circadian rhythm factors were determined with a self-report questionnaire and included breakfast frequency, sleep duration, and work time. Frequency of breakfast was divided into regular breakfast (five to seven times a week) and irregular breakfast (less than five times a week). Sleep duration was divided into less than 7 hours, 7-9 hours, and over 9 hours. Working time was defined as day/evening, night shift, and other type. The adjusted odds ratios (aORs) and 95% confidence intervals (CIs) for general and abdominal obesity were calculated using multivariable logistic regression according to the number of factors that disturb the circadian rhythm.Results: Participants with 1 (aOR 1.34, 95% Cl 1.10-1.61) and ≥2 (aOR 1.62, 95% Cl 1.29-2.05) factors disturbing circadian rhythms were associated with elevated risk for general obesity. Similarly, those with 1 (aOR 1.33, 95% Cl 1.09-1.63) and ≥2 (aOR 1.70, 95% Cl 1.32-2.20) factors had elevated risk for abdominal obesity.Conclusions: Factors disturbing the circadian rhythm were associated with general and abdominal obesity. Additional studies are needed, and associations with metabolic diseases should be investigated.

First principles investigation on energetics, structure, and mechanical properties of amorphous carbon films doped with B, N, and Cl.

Amorphous carbon (a-C) films have received significant attention due to their reliable structures and superior mechanical, chemical and electronic properties, making them a strong candidate as a hard mask material. We investigated the energetics, structure, and electronic and mechanical properties of the B, N, and Cl doped a-C films based on density functional theory (DFT) calculation. Our DFT calculated results clearly show that introducing B and N atoms into a-C films makes the bulk modulus slightly reduced as a function of the concentration increases. Interestingly, it is noted that introducing Cl atom into a-C films makes the bulk modulus is drastically reduced, which suggests that the films softened by Cl doping would relieve residual stress of the individual layers within the overall stacks in integrated semiconductor devices. These requirements become more important and increasingly more challenging to meet as the device integrity grows. In the perspective of F blocking nature, B doping into a-C films pulls in and captures the F atom due to the strong bonding nature of B‒F bond than C-F bond. Unlike the B doping, for the N doped a-C film, F atom has extremely large diffusion barrier of 4.92 eV. This large diffusion barrier is attributed to the electrostatically repulsive force between both atoms. The Cl doped a-C film shows consistently the similar results with the N doped a-C film because both N and Cl atoms have large electro-negativity, which causes F atom to push out. If one notes the optimized designing with the suitable doped characteristics, our results could provide a new straightforward strategy to tailor the a-C films with excellent mechanical and other novel physical and chemical properties.

Effects of H2 and N2 treatment for B2H6 dosing process on TiN surfaces during atomic layer deposition: an ab initio study.

For the development of the future ultrahigh-scale integrated memory devices, a uniform tungsten (W) gate deposition process with good conformal film is essential for improving the conductivity of the W gate, resulting in the enhancement of device performance. As the memory devices are further scaled down, uniform W deposition becomes more difficult because of the experimental limitations of the sub-nanometer scale deposition even with atomic layer deposition (ALD) W processes. Even though it is known that the B2H6 dosing process plays a key role in the deposition of the ALD W layer with low resistivity and in the removal of residual fluorine (F) atoms, the roles of H2 and N2 treatments used in the ALD W process have not yet been reported. To understand the detailed ALD W process, we have investigated the effects of H2 and N2 treatment on TiN surfaces for the B2H6 dosing process using first-principles density functional theory (DFT) calculations. In our DFT calculated results, H2 treatment on the TiN surfaces causes the surfaces to become H-covered TiN surfaces, which results in lowering the reactivity of the B2H6 precursor since the overall reactions of the B2H6 on the H-covered TiN surfaces are energetically less favorable than the TiN surfaces. As a result, an effect of the H2 treatment is to decrease the reactivity of the B2H6 molecule on the TiN surface. However, N2 treatment on the Ti-terminated TiN (111) surface is more likely to make the TiN surface become an N-terminated TiN (111) surface, which results in making a lot of N-terminated TiN (111) surfaces, having a very reactive nature for B2H6 bond dissociation. As a result, the effect of N2 treatment serves as a catalyst to decompose B2H6. From the deep understanding of the effect of H2 and N2 during the B2H6 dosing process, the use of proper gas treatment is required for the improvement of the W nucleation layers.

Overall reaction mechanism for a full atomic layer deposition cycle of W films on TiN surfaces: first-principles study.

We investigated the overall ALD reaction mechanism for W deposition on TiN surfaces based on DFT calculation as well as the detailed dissociative reactions of WF6. Our calculated results suggest that the overall reactions of the WF6 on the B-covered TiN surfaces are energetically much more favorable than the one on the TiN surfaces, which means that the high reactivity of WF6 with the B-covered TiN surface is attributed to the presence of B-covered surface made by B2H6 molecules. As a result, an effect of the B2H6 flow serves as a catalyst to decompose WF6 molecules. Two additional reaction processes right after WF6 bond dissociation, such as W substitution and BF3 desorption, were also explored to clearly understand the detailed reactions that can occur by WF6 flow. At the first additional reaction process, W atoms can be substituted into B site and covered on the TiN surfaces due to the stronger bonding nature of W with the TiN surface than B atoms. At the second additional reaction process, remaining atoms, such as B and F, can be easily desorbed as by-product, that is, BF3 because BF3 desorption is an energetically favorable reaction with a low activation energy. Furthermore, we also investigated the effect of H2 post-treatment on W-covered TiN surface in order to remove residual F adatoms, which are known to cause severe problems that extremely degrade the characteristics of memory devices. It was found that both H2 dissociative reaction and HF desorption can occur sufficiently well under somewhat high temperature and H2 ambience, which is confirmed by our DFT results and previously reported experimental results. These results imply that the understanding of the role of gas molecules used for W deposition gives us insight into improving the W ALD process for future memory devices.

Gender-specific relationship between alcohol consumption and injury in the South Korean adults: A nationwide cross-sectional study.

Alcohol-related injuries have been concerned worldwide. However, there have been no large cross-sectional epidemiologic studies. The aim of this study was to investigate the association between alcohol and the prevalence of injury according to gender in a representative sample of the South Korean population. This cross-sectional study was based on data obtained in the Korea National Health and Nutrition Examination Survey from 2010 to 2012. In total, 15,249 Korean adults (7128 men and 8112 women) aged 19 years or older were enrolled. Injury was defined as the incidence of an injury or intoxication within the year before completing the survey questionnaire. Univariate and multiple logistic regression analyses were conducted to analyze the relationship between alcohol consumption and the prevalence of injury. Heavy alcohol consumption and high-risk drinking were associated with a higher prevalence of injury in women (adjusted odds ratio [aOR] and corresponding 95% confidence interval [CI]: 2.48 [1.321, 4.656], 1.816 [1.136, 2.929], respectively), and Alcohol Use Disorders Identification Test (AUDIT) scores ≥20 were associated with a higher prevalence of injury in both men and women (aOR and 95% CI: 1.425 [1.004, 2.024] and 3.71 [2.067, 6.66], respectively). According to the AUDIT scores results, women who were injured reported significantly more high-risk drinking behaviors per month compared with those who were not injured. Gender disparities in the relationship between alcohol and the prevalence of injury were found. Indeed, future research using a prospective design should examine the causal relationship between alcohol consumption and the prevalence injury according to gender to confirm that alcohol is a risk factor for injury and to identify the possible mechanisms underlying this phenomenon.

The Role of Resorbable Plate and Artificial Bone Substitute in Reconstruction of Large Orbital Floor Defect.

It is essential to reduce and reconstruct bony defects adequately in large orbital floor fracture and defect. Among many reconstructive methods, alloplastic materials have attracted attention because of their safety and ease of use. We have used resorbable plates combined with artificial bone substitutes in large orbital floor defect reconstructions and have evaluated their long-term reliability compared with porous polyethylene plate. A total of 147 patients with traumatic orbital floor fracture were included in the study. Surgical results were evaluated by clinical evaluations, exophthalmometry, and computed tomography at least 12 months postoperatively. Both orbital floor height discrepancy and orbital volume change were calculated and compared with preoperative CT findings. The average volume discrepancy and vertical height discrepancies were not different between two groups. Also, exophthalmometric measurements were not significantly different between the two groups. No significant postoperative complication including permanent diplopia, proptosis, and enophthalmos was noted. Use of a resorbable plate with an artificial bone substitute to repair orbital floor defects larger than 2.5 cm(2) in size yielded long-lasting, effective reconstruction without significant complications. We therefore propose our approach as an effective alternative method for large orbital floor reconstructions.

The Use of Topical Lidocaine Gel During Intermaxillary Fixation Procedure.

This study aimed to validate the usefulness of lidocaine gel during intermaxillary fixation using arch bars in patients with mandible fracture by comparing 2 patient groups: one group using lidocaine gel in intermaxillary fixation and the other group undergoing traditional local infiltration.Subjects were patients with mandible fracture undergoing intermaxillary fixation using arch bars from March 2003 to February 2007. Twenty-three patients were anesthetized in the upper and lower gingiva by 2% local lidocaine solution injection; another 23 underwent topical anesthesia with 2% lidocaine hydrochloride gel applied to the upper and lower gingiva. The convenience of fixation was measured in terms of operation time and degree of pain according to the visual analog scale; arch bar loosening rate was assessed postoperatively.The mean operation times were 63 and 47 minutes in the groups undergoing local infiltration and using topical lidocaine gel, respectively. For pain degree according to the visual analog scale, the mean scores were 6.4 and 3.2 in the groups using local infiltration and topical lidocaine gel, respectively. When the arch bar loosening rate was measured postoperatively, the 2 groups differed significantly, with a rate of 26% in the group using local infiltration and 13% in the group using topical lidocaine gel.Application of topical lidocaine gel during intermaxillary fixation using arch bars in patients with mandible fracture relieves pain and offers convenience in performing the procedure. It can be a useful alternative method for patients who are sensitive to pain or have needle phobia.

Leiomyoma originating from axilla: A rare case report and differential diagnosis.

INTRODUCTION: Leiomyoma is a form of benign tumor originated in hypertrophy of the smooth muscles, which is most prevalent in the uterus and gastrointestinal tract. However, Leiomyoma originating from smooth muscle at the vessels lying on deep soft tissue is very rare. CASE REPORT: Our case was a rare case of leiomyoma originating from the axillary region, which was initially diagnosed as a fibroadenoma on radiological examination. The mass was separated from surrounding tissues and totally resected. Pathologically, hematoxylin-eosin-stained biopsy tissue showed the typical findings of leiomyoma. Postoperative follow-up observation was done for 1 year, without any complications or recurrence. CONCLUSION: Notably, a leiomyoma in the axillary region is difficult to differentiate from other benign or malignant tumors on preoperative radiological examinations such as ultrasonography or computed tomgraphy. Therefore, when an indefinite asymptomatic mass that is not lymphadenopathy or common benign tumor is identified in the axillary region, leiomyoma can be considered as one of the differential diagnoses.

Relationship between chromatographic resolution and amide structure of chiral 2-hydroxy acids as O-(-)-menthoxycarbonylated diastereomeric derivatives for enantiomeric separation on achiral gas chromatography.

The relationship between chromatographic resolution and amide structure of chiral 2-hydroxy acids as O-(-)-menthoxycarbonylated diastereomeric derivatives on achiral gas chromatography was investigated to elucidate the best diastereomeric conformation for enantiomeric separation of chiral 2-hydroxy acids. Thirteen chiral 2-hydroxy acids were converted into nine different diastereomeric O-(-)-menthoxycarbonylated amide derivatives using the primary, secondary and cyclic amines to achieve complete enantiomeric separation through an achiral column. Each enantiomeric pair of 2-hydroxy acids as O-(-)-menthoxycarbonylated tert-butylamide derivatives was resolved on both the DB-5 and DB-17 columns with resolution factors ranging from 1.7 to 4.8 and 1.7 to 3.4, respectively. The results revealed that the structure of the amide moiety is shown to significantly affect chromatographic resolution. In addition, O-(-)-menthoxycarbonylated tert-butylamide derivatives were shown to be the best diastereomeric conformations for enantiomeric separation of 2-hydroxy acids. When comparing with our previous O-trifluoroacetylated(-)-menthyl ester derivatization method, the present results suggested that size differences between groups attached to the chiral center and conformational rigidity can have stronger effects on resolution than the distance between chiral centers. The elution of R- and S-stereoisomers was affected by the class of amine; i.e., primary, secondary, or cyclic, regardless of the substituents on the amine group, the structure of the 2-hydroxy acid, and the polarity of the column.

Relationships between structure, ionization profile and sensitivity of exogenous anabolic steroids under electrospray ionization and analysis in human urine using liquid chromatography-tandem mass spectrometry.

The relationships between the ionization profile, sensitivity, and structures of 64 exogenous anabolic steroids (groups I-IV) was investigated under electrospray ionization (ESI) conditions. The target analytes were ionized as [M + H](+) or [M + H-nH2 O](+) in the positive mode, and these ions were used as precursor ions for selected reaction monitoring analysis. The collision energy and Q3 ions were optimized based on the sensitivity and selectivity. The limits of detection (LODs) were 0.05-20 ng/mL for the 64 steroids. The LODs for 38 compounds, 14 compounds and 12 compounds were in the range of 0.05-1, 2-5 and 10-20 ng/mL, respectively. Steroids including the conjugated keto-functional group at C3 showed good proton affinity and stability, and generated the [M + H](+) ion as the most abundant precursor ion. In addition, the LODs of steroids using the [M + H](+) ion as the precursor ion were mostly distributed at low concentrations. In contrast, steroids containing conjugated/unconjugated hydroxyl functional groups at C3 generated [M + H - H2 O](+) or [M + H - 2H2 O](+) ions, and these steroids showed relatively high LODs owing to poor stability and multiple ion formation. An LC-MS/MS method based on the present ionization profile was developed and validated for the determination of 78 steroids (groups I-V) in human urine.

Dependency of Experimental Autoimmune Encephalomyelitis Induction on MOG35-55 Properties Modulating Matrix Metalloproteinase-9 and Interleukin-6.

Experimental autoimmune encephalomyelitis (EAE) is commonly induced with myelin oligodendrocyte glycoprotein (MOG)35-55; occasionally, EAE is not well induced despite MOG35-55 immunization. To confirm that EAE induction varies with difference in MOG35-55 properties, we compared three MOG35-55 from different commercial sources, which are MOG-A, MOG-B, and MOG-C. The peptides induced EAE disease with 100, 40, and 20 % incidence, respectively. Compared with others, MOG-A showed higher peptide purity (99.2 %) and content (92.2 %) and presented a sheet shape with additional sodium and chloride chemical elements. In MOG-A-treated group, MMP-9 activity and IL-6 levels were considerably higher than the other groups in CNS tissues, and significantly increased VCAM-1, IFN-γ, and decreased IL-4 were also shown compared to MOG-B- and/or MOG-C-treated group. In conclusion, the immunological and toxicological changes by the difference in MOG35-55 properties modulate EAE induction, and MOG35-55 which affects MMP-9 activity and IL-6 levels may be the most effective EAE-inducing antigen. This study can be potentially applied by researchers using MOG35-55 peptide and manufacturers for MOG35-55 synthesis.