Experimental Validation of Comprehensive Calculation for High-Resolution Linear MALDI-TOF Mass Spectrometry.

This work discusses the effectiveness of the previously developed comprehensive calculation model to optimize linear MALDI-TOF mass spectrometers. The model couples space- and velocity-focusing to precisely analyze the flight-time distribution of ions and predict optimal experimental parameters for the highest mass resolving power. Experimental validation was conducted using a laboratory-made instrument to analyze CsI3 and angiotensin I ions in low to medium m/z range. The results indicate that the predicted optimal extraction voltage and delay were reasonably accurate and effective. In the low m/z range, the peak width obtained using optimal parameters reached the sub nanosecond range, corresponding to a mass resolving power of 10 000-17 000, or 20 000-34 000 if shot-to-shot random fluctuations were minimized by the dynamic data correction method. The observed optimal mass resolving power in the current experiment is 4.8-7.8 times that of commercial instruments. Practical limitations resulting in the gap between the observed and theoretical ultimate mass resolving power are discussed.

Risk of bullous pemphigoid and pemphigus in patients on chronic dialysis: A nationwide population-based cohort study.

Bullous pemphigoid has a high incidence among dialysis patients. However, whether or not chronic dialysis is an independent risk factor of bullous pemphigoid remains unclear. We aimed to investigate the effect of chronic dialysis on the development of bullous pemphigoid and pemphigus. We performed a retrospective cohort study using records from Taiwan's National Health Insurance Research Database between 2008 and 2019. We identified a dialysis cohort that included patients on chronic hemodialysis and peritoneal dialysis, and the hazard ratios (HRs) for bullous pemphigoid and pemphigus were compared with those of a sex-, age-, and index-matched cohort, then the results were adjusted for various confounding factors. Among 93 538 patients on chronic dialysis and 93 538 patients in the control group, 287 and 139 developed incident bullous pemphigoid, and 45 and 35 developed incident pemphigus after a median follow-up of 3.7 and 5.6 years, respectively. The incidence rates of bullous pemphigoid in the dialysis patients and the control group were 74.2 and 25.2 per 100 000 person-years, respectively (difference between groups, P < 0.0001). The incidence rates of pemphigus in the dialysis patients and the control group were 11.6 and 6.3 per 100 000 person-years, respectively (difference between groups, P < 0.01). Cox proportional hazard adjustment showed the HR for bullous pemphigoid in dialysis patients was 2.12 (95% confidence interval [CI] 1.64-2.74, P < 0.0001) compared with the control group. Dialysis patients aged <75 years had an even higher risk of bullous pemphigoid development (5- to 8-fold) than the control group. The adjusted HR for pemphigus was not elevated in dialysis patients (adjusted HR 1.52, 95% CI 0.87-2.67, P = 0.14). Chronic dialysis is an independent risk factor for developing bullous pemphigoid, but not a risk factor for pemphigus. Physicians should be aware of the predisposition of chronic dialysis patients to bullous pemphigoid.

Anti-Inflammatory Effects of Cycloheterophyllin on Dinitrochlorobenzene-Induced Atopic Dermatitis in HaCaT Cells and BALB/c Mice.

Atopic dermatitis (eczema) is a condition that makes skin red and itchy. Though common in children, the condition can occur at any age. Atopic dermatitis is persistent (chronic) and tends to recur periodically. It may be accompanied by asthma or hay fever. No cure has been found for eczema. Therefore, it is very important to develop ingredients that aid the prevention and treatment of atopic dermatitis. Cycloheterophyllin is derived from Artocarpus heterophyllus and has antioxidant and anti-inflammatory activities. However, it still is not understood whether cycloheterophyllin is an anti-atopic dermatitis agent. Keratinocytes (HaCaT cells) and BALB/c mice for inducing AD-like cutaneous lesions were used to evaluate the potential of cycloheterophyllin as an anti-atopic dermatitis agent. The release of pro-inflammatory cytokines induced by treatment of TNF-α/IFN-γ was reduced after pretreatment with cycloheterophyllin. The inhibitory effects could be a contribution from the effect of the MAP kinases pathway. Moreover, the symptoms of atopic dermatitis (such as red skin and itching) were attenuated by pretreatment with cycloheterophyllin. Epidermal hyperplasia and mast cell infiltration were decreased in the histological section. Finally, damage to the skin barrier was also found to recover through assessment of transepidermal water loss. Taken together, prenylflavone-cycloheterophyllin from Artocarpus heterophyllus is a potential anti-atopic dermatitis ingredient that can be used in preventing or treating the condition.

Comparison of picosecond versus nanosecond Nd:YAG lasers for the removal of cosmetic tattoos in an animal model.

Cosmetic tattoos are difficult to remove, and their response to picosecond laser treatment has seldom been investigated. We compared the efficacy and adverse effects of picosecond versus Q-switched lasers for the removal of cosmetic tattoos. White, flesh-colored, and brown inks were irradiated using 532/1064 nm picosecond and Q-switched Nd:YAG lasers, and their absorption spectra before and after laser irradiation were analyzed. Nine rats were tattooed with all three inks. Each tattoo was divided into three sections and treated at 1064 nm with a picosecond laser or Q-switched laser, or left untreated, in four sessions at 1-month intervals. Skin biopsies were taken from treated and untreated sites. In vitro study showed the 1064 nm picosecond laser caused the least paradoxical color shift. In vivo study showed that all white tattoos achieved poor response scores, six flesh-colored tattoos achieved fair to good response scores, and seven brown tattoos achieved good to excellent response scores with the picosecond laser. The picosecond laser was superior to the Q-switched laser for removing flesh-colored tattoos (P < 0.05), but the effectiveness for white and brown tattoos was similar for both lasers. The degree of paradoxical darkening when removing the white and flesh-colored tattoos was significantly lower with the picosecond than that with the Q-switched laser (P < 0.01). Transmission electron microscopy showed that many tattoo ink particles had decreased in size after irradiations with both pulse durations. The 1064 nm picosecond Nd:YAG laser causes mild paradoxical darkening and might be more appropriate for removal of flesh-colored and brown cosmetic tattoos.

Digitizing Scoring Systems With Extended Online Feedback: A Novel Approach to Interactive Teaching and Learning in Formative OSCE.

OBJECTIVES: Objective structured clinical examinations (OSCEs) are common for formative assessment. We developed an Online Smart Communicative Education System and aimed to explore the factors that affect the perceptions of both teachers and students for teaching and learning. METHODS AND ANALYSIS: A two-year cross-sectional cohort study was undertaken. The program includes three parts. Part I Pre-OSCE: an online flipped class in preparation for task-related knowledge and skills. Part II OSCE-day: 10 tasks in one track formative OSCE. Part III Post-OSCE: extended online feedback for participants with further questions after the exam and raters with more feedback after reviewing their performance online. Principal component analysis with varimax rotation was performed to analyze the perceptions of students and teachers to the Online System by means of questionnaires. RESULTS: Seventy-six pharmacy students (male 32.9%) took the exam and 24 raters (male, 25%) participated in the scoring during the OSCEs. The mean G coefficient was 0.88. Seventy-six questionnaires from the students were obtained for the analysis. Results explained the cumulative variance of 73.9% for component (1) "Effects of extended online feedback": 40% and (2) "Facilitation of learning": 33.9%. Thirty-nine questionnaires from the raters who experienced the Online System were obtained for the analysis (male 23.1%). Results explained a cumulative variance of 77.3% for component (1) "Effects of extended online feedback": 36.6%, (2) "Facilitation of scoring and feedback": 24.5%, and (3) "Feasibility of online platform": 16.2%, respectively. CONCLUSION: We demonstrated good reliability for digitizing the scoring system with educational support to facilitate teaching. "Effects of extended online feedback" was the major aspect in explaining the variance from the perceptions of students and raters by factor analysis. In comparison with traditional formative OSCEs, extended online feedback is a novel approach, which extends the process of learning and teaching among the learners and raters and overcomes the barriers of time limitation and distance.

Increased Risk of Cutaneous Squamous Cell Carcinoma in Organ Transplant Recipients and Patients on Chronic Dialysis: A Cancer Registry-based Study in Taiwan.

This study investigated the predominant skin cancer subtype among organ transplant recipients, patients on chronic dialysis, and patients with chronic kidney disease in Asian subjects. Among 23,644 patients with skin cancer, identified from Taiwan Cancer Registry Database, 53 were organ transplant recipients, 255 were on chronic dialysis, 1,792 had chronic kidney disease, and 21,544 were in the control group. The proportions of squamous cell carcinoma were 52.8%, 47.8%, 40.1%, and 33.5%, respectively. Compared with the control group, organ transplant recipients (1.99-fold) and patients on chronic dialysis (1.25-fold) were at higher risk of developing squamous cell carcinoma than other skin cancers after adjustment for potential confounders. Subgroups or covariates associated with increased squamous cell carcinoma compared with other skin cancer risk included patients with chronic kidney disease aged < 70 years (vs. control group; 1.3-fold), old age (vs. young age; 2.8-fold), male sex (vs. female sex; 1.1-fold), and south Taiwan residency (vs. north Taiwan residency; 1.1-fold). Organ transplant recipients and patients on chronic dialysis had immune dysregulation, resulting in a higher risk of squamous cell carcinomas.

Effective analysis of degree of polymerization of polysialic acids in mass spectrometry by combining novel sample preparation and dynamic instrument optimization methods.

This work demonstrates a mass spectrometry technique to improve data reliability when analyzing degree of polymerization (DP) of high-mass polysialic acids (PSAs). Matrix-assisted laser-desorption/ionization (MALDI) time-of-flight mass spectrometry is the technique of choice for analyzing large molecules due to its wide mass working range; however, the observed DP of PSAs using such an instrument is unreliable owing to sensitivity bias towards low-mass ions. A multi-layer MALDI sample preparation protocol is demonstrated in the current study to improve PSA sensitivity, and a dynamic instrument optimization method (DIOM) is employed to minimize detector saturation over a wide mass range. The DP information obtained in the DIOM combines a series of mass spectral data obtained with individually optimized instrument parameters to minimize the problem of sensitivity bias in respective mass ranges. The resultant mass spectra facilitate unambiguous determination of DP in the high-mass range due to significantly improved spectral quality. The main instrument parameters involved in the optimization process include extraction delay in MALDI ion source as well as the cutoff mass of the ion detector. In comparison to conventional methods, the DIOM doubles the maximum DP that can be unambiguously identified by mass spectrometry.

Cross-section and feasibility study on the non-invasive evaluation of muscle hemodynamic responses in Duchenne muscular dystrophy by using a near-infrared diffuse optical technique.

Duchenne muscular dystrophy (DMD) is an X-linked debilitating muscular disease that may decrease nitric oxide (NO) production and lead to functional muscular ischemia. Currently, the 6-minute walk test (6-MWT) and the North Star Ambulatory Assessment (NSAA) are the primary outcome measures in clinical trials, but they are severely limited by the subjective consciousness and mood of patients, and can only be used in older and ambulatory boys. This study proposed using functional near-infrared spectroscopy (fNIRS) to evaluate the dynamic changes in muscle hemodynamic responses (gastrocnemius and forearm muscle) during a 6-MWT and a venous occlusion test (VOT), respectively. Muscle oxygenation of the forearm was evaluated non-invasively before, during and after VOT in all participants (included 30 DMD patients and 30 age-matched healthy controls), while dynamic muscle oxygenation of gastrocnemius muscle during 6-MWT was determined in ambulatory participants (n = 18) and healthy controls (n = 30). The results reveal that impaired muscle oxygenation was observed during 6-MWT in DMD patients that may explain why the DMD patients walked shorter distances than healthy controls. Moreover, the results of VOT implied that worsening muscle function was associated with a lower supply of muscle oxygenation and may provide useful information on the relationship between muscular oxygen consumption and supply for the clinical diagnosis of DMD. Therefore, the method of fNIRS with VOT possesses great potential in future evaluations of DMD patients that implies a good feasibility for clinical application such as for monitoring disease severity of DMD.

Increased risk of incident psoriasis in end-stage renal disease patients on chronic hemodialysis: A nationwide population-based cohort study.

Patients with end-stage renal disease (ESRD) on chronic hemodialysis (HD) experience chronic inflammation and immune dysregulation; whether these affect the development of chronic inflammatory disease such as psoriasis is unknown. We aimed to investigate the impact of ESRD on the development of psoriasis. We performed a retrospective cohort study using records between 1999 and 2013 from Taiwan's National Health Insurance Research Database. Among 74 916 patients with ESRD on chronic HD and the control group comprising 74 916 sex and age group-matched patients, 165 and 81 incident psoriasis developed after a mean follow up of 2.4 and 2.9 years, respectively. The incidence rates of psoriasis in HD patients and the control group were 91.7 and 37.1 per 100 000 person-years, respectively (difference between groups, P < 0.001). HD patients had a shorter time to psoriasis diagnosis than the control group (P < 0.05). Cox proportional hazard adjustment showed the hazard ratio (HR) for psoriasis in HD patients as 2.09 (95% confidence interval [CI], 1.49-2.94; P < 0.001) than that of the control group. Younger HD patients had relatively higher risk of psoriatic development (age <60 years; adjusted HR, 3.68; 95% CI, 1.93-7.02; P < 0.001). The relative risk of psoriatic arthritis was not increased in HD patients compared with the control group. In conclusion, patients with ESRD on chronic HD had a greater risk of developing psoriasis. Physicians should be aware of the predisposition to psoriasis in patients with ESRD on chronic HD.

Risk of Non-melanoma Skin Cancer in Patients with Chronic Kidney Disease and its Relationship to Uraemic Pruritus.

This study investigated the risk of non-melanoma skin cancer (NMSC) in pre-dialysis patients with chronic kidney disease (CKD) and explored associated risk factors. A population-based cohort of 1,515,858 Taiwanese CKD patients was included. The standardized incidence ratio (SIR) for incident NMSC was determined. Compared with the general population, a 1.14-fold risk of NMSC was found in the CKD cohort. NMSC risk was significant in patients with pre-dialysis stage 5 CKD and anaemia (1.48-fold), and in those with uraemic pruritus after long-term antihistamine treatment (1.38-fold). A higher SIR for NMSC was found in younger patients with CKD (age < 70 years, 1.34-fold; age 20-39 years, 1.63-fold), stage 5 CKD with anaemia (age < 70 years, 2.09-fold), and uraemic pruritus (age <70 years, 2.22-fold). Pre-dialysis patients with CKD are at higher risk of NMSC, especially those with advanced-stage CKD, and those with uraemic pruritus.

Critical factors determining the quantification capability of matrix-assisted laser desorption/ionization- time-of-flight mass spectrometry.

Quantitative analysis with mass spectrometry (MS) is important but challenging. Matrix-assisted laser desorption/ionization (MALDI) coupled with time-of-flight (TOF) MS offers superior sensitivity, resolution and speed, but such techniques have numerous disadvantages that hinder quantitative analyses. This review summarizes essential obstacles to analyte quantification with MALDI-TOF MS, including the complex ionization mechanism of MALDI, sensitive characteristics of the applied electric fields and the mass-dependent detection efficiency of ion detectors. General quantitative ionization and desorption interpretations of ion production are described. Important instrument parameters and available methods of MALDI-TOF MS used for quantitative analysis are also reviewed.This article is part of the themed issue 'Quantitative mass spectrometry'.

Do Automated Peritoneal Dialysis and Continuous Ambulatory Peritoneal Dialysis Have the Same Clinical Outcomes? A Ten-year Cohort Study in Taiwan.

This paper reports a comprehensive comparison for mortality and technique failure rates between automated peritoneal dialysis (APD) and continuous ambulatory peritoneal dialysis (CAPD) in Taiwan. A propensity-score matched cohort study was conducted by retrieving APD and CAPD patients identified from the Taiwan National Health Insurance Research Database between 2001 and 2010. The main outcomes were the 5-year mortality and technique failure rates. Further analyses were then carried out based upon the first (2001-2004), second (2005-2007), and third (2008-2010) sub-periods. Similar baseline characteristics were identified for APD (n = 2,287) and CAPD (n = 2,287) patients. The proportion on APD therapy increased rapidly in the second sub-period. As compared to CAPD patients of this sub-period, APD patients had a significantly higher risk of mortality (HR, 1.37; 95% CI 1.09-1.72; p < 0.01) and technique failure (HR, 1.43; 95% CI, 1.10-1.86; p < 0.01), particularly in the first year after peritoneal dialysis commencement. However, APD patients had similar mortality and technique failure rates to those of CAPD patients throughout the full sample period and the first and third sub-periods. These findings do not suggest the presence of a clear advantage of CAPD over APD. Differences observed between these two modalities might be attributed to specials circumstances of sub-periods.

Prognostic Benefits of Carvedilol, Bisoprolol, and Metoprolol Controlled Release/Extended Release in Hemodialysis Patients with Heart Failure: A 10-Year Cohort.

BACKGROUND: Heart failure is a highly prevalent cardiovascular complication among patients receiving long-term hemodialysis, but the benefits of carvedilol, bisoprolol, and metoprolol controlled release/extended release on the outcomes of these patients remain unclear. In this study, we address the use of these 3 ß-blockers and their associations with mortality. METHODS AND RESULTS: Long-term hemodialysis patients, aged ≥35 years, with new-onset heart failure and receiving various medications were identified through the use of 1999-2010 data from the Taiwan National Health Insurance Research Database. From the total of 4435 heart failure patients, we selected 1700 new users of the 3 ß-blockers (study group) and 1700 nonusers (control group), by using matched cohorts according to their propensity scores, and then compared the 5-year all-cause mortality rates by using Cox proportional hazard regressions and time-dependent covariate adjustment. During 3944 person-years of follow-up, 666 (39.2%) deaths occurred within the study group, compared with 918 (54%) deaths during 2893 person-years of follow-up in the control group. The 5-year mortality rate for the study (control) group was 54.5% (70.3%); P<0.001. Adjusted hazard regression analyses revealed that the therapeutic effects of ß-blockers remained significant for all-cause mortality (hazard ratio 0.80, 95% CI 0.72 to 0.90). Subgroup analyses revealed that patients in the study group receiving ß-blockers plus renin-angiotensin system antagonists exhibited the lowest mortality rate, while the highest mortality rate was found among patients in the control group receiving neither ß-blockers nor renin-angiotensin system antagonists. CONCLUSIONS: This study demonstrates that the 3 ß-blockers were associated with improved survival in long-term hemodialysis patients with heart failure.

Effects of tattoo ink's absorption spectra and particle size on cosmetic tattoo treatment efficacy using Q-switched Nd:YAG laser.

The mechanisms responsible for variable responses of cosmetic tattoos to Q-switched laser removal treatment remain unclear. We sought to investigate the properties of tattoo inks that may affect the efficacy of laser-assisted tattoo removal. The absorption of white, brown, and black inks before and after Q-switched neodymium-doped yttrium aluminum garnet laser irradiation were analyzed by a reflectance measurement system. Rats were tattooed using the three inks and treated with the same laser for two sessions. Skin biopsies were taken from the treated and untreated sites. Black ink showed strong absorption, reduced after laser irradiation, over the entire spectrum. White ink had low absorption over the visible light spectrum, and brown ink had strong absorption at 400-550 nm wavelengths. White and brown inks turned dark after laser exposure, and the absorption of laser-darkened inks were intermediate between their original color and black ink. White, brown, and black tattoos in rat skin achieved poor, fair to good, and excellent responses to laser treatment, respectively. Transmission electron microscopy showed that white tattoo particles were the largest, brown were intermediate, and black were the smallest before laser. After laser treatment, white and brown tattoo particles were mixtures of large and small particles, while black particles showed overall reduction in number and size. Black tattoo ink's excellent response to Q-switched lasers was associated with its strong absorption and small particle size. White tattoo ink's poor response was associated with its poor absorption, even after laser darkening, and large particle size.

Renin-angiotensin system blockade in heart failure patients on long-term haemodialysis in Taiwan.

AIMS: Heart failure is among the most frequent complications of patients on long-term haemodialysis. The benefits of renin-angiotensin system (RAS) blockade on the outcomes of these patients have yet to be determined. METHODS AND RESULTS: We conducted a nationwide observational study using data from the Taiwan National Health Insurance claims database, between 1999 and 2010. We enrolled patients aged ≥35 years with new-onset heart failure [diagnosed by International Classification of Diseases, 9th revision, clinical modification (ICD-9-CM) codes] under treatment with medications. New users of a RAS blocker (RASB; i.e., an ACE inhibitor or an ARB used as monotherapy or dual therapy) were selected to compare with non-RASB users. We used Cox proportional hazards regression with and without propensity score adjustment to compare the risk of 3-year all-cause and cardiovascular mortality. Stratified analyses and RASB therapy duration as a time-dependent covariate were also performed. In all, 4771 were treated with an RASB (n = 3024) or without an RASB (n = 1747). RASB users had a higher prevalence of hypertension and diabetes, and a higher number of hospitalization. Among RASB users, 1148 deaths (38.0%) occurred during 5272 person-years of follow-up compared with 734 deaths (42.0%) among non-RASB users during 2683 person-years of follow-up. Three-year mortality rates were 45.4% and 49.1% for patients receiving and those not receiving an RASB, respectively (log-rank test, P < 0.001). Adjusted hazard analysis revealed that RASB therapeutic effects remained significant on all-cause [hazard ratio (HR) 0.8; 95% confidence interval (CI) 0.72-0.89; P < 0.001] and cardiovascular mortality (HR 0.76; 95% CI 0.64-0.90; P < 0.01). CONCLUSIONS: RASB therapy reduced all-cause and cardiovascular mortality in heart failure patients on long-term haemodialysis.

Selective enhancement of carbohydrate ion abundances by diamond nanoparticles for mass spectrometric analysis.

Diamond nanoparticles (DNPs) were incorporated into matrix-assisted laser desorption/ionization (MALDI) samples to enhance the sensitivity of the mass spectrometer to carbohydrates. The DNPs optimize the MALDI sample morphology and thermalize the samples for thermally labile compounds because they have a high thermal conductivity, a low extinction coefficient in UV-vis spectral range, and stable chemical properties. The best enhancement effect was achieved when matrix, DNP, and carbohydrate solutions were deposited and vacuum-dried consecutively to form a trilayer sample morphology. It allows the direct identification of underivatized carbohydrates mixed with equal amount of proteins because no increase in the ion abundance of proteins was achieved. For dextran with an average molecular weight of 1500, the trilayer method typically improves the sensitivity by 79- and 7-fold in comparison to the conventional dried-droplet and thin-layer methods, respectively.

Treatment of cosmetic tattoos with nonablative fractional laser in an animal model: a novel method with histopathologic evidence.

BACKGROUND AND OBJECTIVE: Cosmetic tattoos are difficult to treat using Q-switched lasers. We introduce a novel method for the treatment of cosmetic tattoos using a nonablative fractional laser and investigate the underlying pathophysiological mechanisms in an animal model. STUDY DESIGN/MATERIALS AND METHODS: Ten rats were tattooed on their backs with white and flesh-colored pigments. One-half of each tattoo was treated with a 1,550-nm, erbium:glass fractional laser system with energy settings of 17 mJ and 169 MTZ/cm(2) × 2 passes for five sessions at 1-month intervals. The untreated half of each tattoo served as the control. An independent physician reviewed the photographs and scored the clinical response. Serial skin samples were obtained at baseline and at various times after laser treatment. These tissue sections were stained with hematoxylin and eosin, and immunostained for types I, III, and IV collagen; laminin; fibronectin; and α-smooth muscle actin. RESULTS: White tattoos showed excellent responses in two rats and good responses in eight rats, whereas flesh-colored tattoos showed excellent responses in four rats and good responses in six rats (P = 0.001 in both cases compared with baseline). Both tattoos exhibited a similar clearance rate (P > 0.05) and histological reactions. Microscopic epidermal necrotic debris (MEND) containing tattoo pigments and collagen fibrils appeared on day 1, increased on day 2, and was exfoliated after 5 days. The dermal-epidermal junction lost integrity 30 minutes after treatment, but recovered completely on day 3. The expression of fibronectin and collagen-III, which play key roles in wound healing, increased around the microscopic treatment zone on days 1-5 and 4-7, respectively. A few myofibroblasts appeared on days 4-7. CONCLUSION: Nonablative fractional lasers (NAFLs) successfully remove cosmetic tattoos by transepidermal elimination of tattoo pigments through the disrupted dermal-epidermal junction. This action is facilitated by the wound healing process.