Association between exposure to specific PM2.5 constituents and environment, lifestyle, and clinical parameters in patients with COPD.

This study investigated the correlation between the individual chemical constituents of particulate matter 2.5 µm (PM2.5) and respiratory parameters as well as the living environment and daily behaviors in patients with chronic obstructive pulmonary disease (COPD). Data were obtained from prospective COPD panel conducted in South Korea. Following collection via a microPEM, 18 metallic elements were determined using energy-dispersive X-ray fluorescence spectroscopy. All participants completed detailed questionnaires on living environments and lifestyle practices. Eighty-nine stable COPD patients (mean age 68.1 years; 94.4% male) were analyzed. Several constituents (titanium, aluminum, bromine, and silicone) were significantly associated with respiratory outcomes. Copper and manganese concentrations were significantly associated with the living environment. Increased ventilation time and air purifier operation were associated with lower concentrations of copper, silicone, barium, and titanium. These findings suggest varying relationships between PM2.5 constituents and clinical parameters in COPD patients, providing a basis for personalized interventions and future research.

Endobronchial valves for emphysema and persistent air-leak: 10-year experience in an Asian country.

BACKGROUND: Endobronchial valve (EBV) therapy, a validated method for bronchoscopic lung volume reduction (BLVR) in severe emphysema, has been explored for persistent air-leak (PAL) management. However, its effectiveness and safety in the Asian population require further real-world evaluation. In this study, we assessed the outcomes of treatment with EBV within this demographic. METHODS: We conducted a retrospective analysis of medical records from 11 Korean centers. For the emphysema cohort, inclusion criteria were patients diagnosed with emphysema who underwent bronchoscopy intended for BLVR. We assessed these patients for clinical outcomes of chronic obstructive pulmonary disease. All patients with PAL who underwent treatment with EBV were included. We identified the underlying causes of PAL and evaluated clinical outcomes after the procedure. RESULTS: The severe emphysema cohort comprised 192 patients with an average age of 70.3 years, and 95.8% of them were men. Ultimately, 137 underwent treatment with EBV. Three months after the procedure, the BLVR group demonstrated a significant improvement in forced expiratory volume in 1 s (+160 mL vs. +30 mL; P = 0.009). Radiographic evidence of lung volume reduction 6 months after BLVR was significantly associated with improved survival (adjusted hazard ratio 0.020; 95% confidence interval 0.038-0.650; P = 0.010). Although pneumothorax was more common in the BLVR group (18.9% vs. 3.8%; P = 0.018), death was higher in the no-BLVR group (38.5% vs. 54.5%, P = 0.001), whereas other adverse events were comparable between the groups. Within the subset of 18 patients with PAL, the predominant causes of air-leak included spontaneous secondary pneumothorax (44.0%), parapneumonic effusion/empyema (22.2%), and post-lung resection surgery (16.7%). Following the treatment, the majority (77.8%) successfully had their chest tubes removed. Post-procedural complications were minimal, with two incidences of hemoptysis and one of empyema, all of which were effectively managed. CONCLUSIONS: Treatment with EBV provides substantial clinical benefits in the management of emphysema and PAL in the Asian population, suggesting a favorable outcome for this therapeutic approach.

Fine particulate matter aggravates smoking induced lung injury via NLRP3/caspase-1 pathway in COPD.

BACKGROUND: Exposure to noxious particles, including cigarette smoke and fine particulate matter (PM2.5), is a risk factor for chronic obstructive pulmonary disease (COPD) and promotes inflammation and cell death in the lungs. We investigated the combined effects of cigarette smoking and PM2.5 exposure in patients with COPD, mice, and human bronchial epithelial cells. METHODS: The relationship between PM2.5 exposure and clinical parameters was investigated in patients with COPD based on smoking status. Alveolar destruction, inflammatory cell infiltration, and pro-inflammatory cytokines were monitored in the smoking-exposed emphysema mouse model. To investigate the mechanisms, cell viability and death and pyroptosis-related changes in BEAS-2B cells were assessed following the exposure to cigarette smoke extract (CSE) and PM2.5. RESULTS: High levels of ambient PM2.5 were more strongly associated with high Saint George's respiratory questionnaire specific for COPD (SGRQ-C) scores in currently smoking patients with COPD. Combined exposure to cigarette smoke and PM2.5 increased mean linear intercept and TUNEL-positive cells in lung tissue, which was associated with increased inflammatory cell infiltration and inflammatory cytokine release in mice. Exposure to a combination of CSE and PM2.5 reduced cell viability and upregulated NLRP3, caspase-1, IL-1ß, and IL-18 transcription in BEAS-2B cells. NLRP3 silencing with siRNA reduced pyroptosis and restored cell viability. CONCLUSIONS: PM2.5 aggravates smoking-induced airway inflammation and cell death via pyroptosis. Clinically, PM2.5 deteriorates quality of life and may worsen prognosis in currently smoking patients with COPD.

Lifestyle practices that reduce seasonal PM2.5 exposure and their impact on COPD.

Particulate matter (PM) is a major air pollutant that has led to global health concerns and can cause and exacerbate chronic obstructive pulmonary disease (COPD). We asked patients with COPD to complete a detailed questionnaire about their lifestyle practices to reduce PM2.5 exposure and analyzed the relationship between ambient PM2.5 concentrations and lifestyle practices. We prospectively enrolled 104 COPD patients from four hospitals in different areas of Korea. They completed detailed questionnaires twice (at enrollment and the end of the study) and Internet of Things-based sensors were installed in their homes to continuously measure PM2.5 for 1 year. The relationship between PM2.5 concentrations, lifestyle practices, and COPD exacerbations were analyzed in each season. The PM2.5 concentration was higher outdoors than indoors in all seasons except summer, and the difference was largest in winter. The six lifestyle practices that significantly lowered the annual indoor PM2.5 concentration compared with the outdoors. The higher the economic status and educational level of patients, the lower the indoor PM2.5 concentration. Some lifestyle practices were associated with reduced small airway resistance, presented as R5-R20 determined by impulse oscillometry, and scores of the St. George's Respiratory Questionnaire. Some lifestyle practices are associated with reduced indoor PM2.5 concentrations and can even affect clinical outcomes, including small airway resistance and quality of life of COPD patients.

Clinical Characteristics of Post-COVID-19 Persistent Cough in the Omicron Era.

Cough is one of the most common symptoms of acute coronavirus disease 2019, but cough may persist for weeks or months. This study aimed to examine the clinical characteristics of patients with post-coronavirus disease (COVID) persistent cough in the Omicron era. We conducted a pooled analysis comparing 3 different groups: 1) a prospective cohort of post-COVID cough (> 3 weeks; n = 55), 2) a retrospective cohort of post-COVID cough (> 3 weeks; n = 66), and 3) a prospective cohort of non-COVID chronic cough (CC) (> 8 weeks; n = 100). Cough and health status was assessed using patient-reported outcomes (PROs). Outcomes, including PROs and systemic symptoms, were longitudinally evaluated in the prospective post-COVID cough registry participants receiving usual care. A total of 121 patients with post-COVID cough and 100 with non-COVID CC were studied. Baseline cough-specific PRO scores did not significantly differ between post-COVID cough and non-COVID CC groups. There were no significant differences in chest imaging abnormality or lung function between groups. However, the proportions of patients with fractional exhaled nitric oxide (FeNO) ≥ 25 ppb were 44.7% in those with post-COVID cough and 22.7% in those with non-COVID CC, which were significantly different. In longitudinal assessment of the post-COVID registry (n = 43), cough-specific PROs, such as cough severity or Leicester Cough Questionnaire (LCQ) scores, significantly improved between visits 1 and 2 (visit interval: median 35 [interquartile range, IQR: 23-58] days). In the LCQ score, 83.3% of the patients showed improvement (change ≥ +1.3), but 7.1% had worsened (≤ -1.3). The number of systemic symptoms was median 4 (IQR: 2-7) at visit 1 but decreased to median 2 (IQR: 0-4) at visit 2. In summary, post-COVID persistent cough was similar in overall clinical characteristics to CC. Current cough guideline-based approaches may be effective in most patients with post-COVID cough. Measurement of FeNO levels may also be useful for cough management.

Safety and outcomes of "at-home self-provocation tests" in patients with mild nonsteroidal anti-inflammatory drug-induced urticaria/angioedema.

BACKGROUND: Nonsteroidal anti-inflammatory drug (NSAID) hypersensitivity is common; however, many patients do not receive an accurate diagnosis and are using unnecessary alternative drugs or have medication restrictions. OBJECTIVE: To establish a protocol for provocation tests that can be performed safely and effectively at home to give patients an accurate diagnosis, whereas also delabeling NSAID hypersensitivity. METHODS: We retrospectively analyzed the medical records of 147 patients with NSAID hypersensitivity. All patients had NSAID-induced urticaria/angioedema with less than 10% body surface area skin involvement. One specialist developed the protocol through history taking and chart review. If NSAID hypersensitivity was confirmed, an oral provocation test was performed to confirm the safe alternative medications (group A). If it was undetermined, an oral provocation test was performed to confirm the diagnosis and alternative medications (group B). All oral provocation tests were performed by patients in their homes according to the protocol. RESULTS: Approximately 26% of group A patients had urticaria or angioedema symptoms with alternative drugs, whereas the remaining 74% was safe. In group B, 34% of the patients were diagnosed with having NSAID hypersensitivity. However, 61% did not respond to the culprit drug; therefore, NSAID hypersensitivity had been misdiagnosed. During this at-home self-provocation test, no severe hypersensitivity reactions occurred. CONCLUSION: Many patients originally suspected of having NSAID hypersensitivity were confirmed to have been misdiagnosed. We successfully conducted an effective and safe at-home self-provocation test.

Efficacy and safety of combination therapy with pirfenidone and nintedanib in patients with idiopathic pulmonary fibrosis.

Background: Recent studies have suggested that combination therapy with pirfenidone and nintedanib is safe and tolerable in patients with idiopathic pulmonary fibrosis (IPF). However, data from real-world practice are limited. Thus, we aimed to investigate the safety and efficacy of this combination therapy in patients with IPF in a real-world setting. Methods: A multicenter retrospective cohort study was conducted to investigate the safety and efficacy of combination therapy with pirfenidone and nintedanib in 45 patients with IPF. Incidences of adverse events and rates of lung function decline were compared before and after the combination therapy. Propensity score matching was performed to compare the outcomes between the combination and monotherapy groups. Results: The mean age of the patients was 68.8 years, and 82.2% of them were male. The median follow-up duration after combination therapy was 12.1 months. The majority of the patients (97.8%) received nintedanib as an add-on to pirfenidone. The most common adverse events after the combination therapy were diarrhea and anorexia. Pirfenidone or nintedanib was stopped in 12 patients owing to gastrointestinal AEs, lung transplantation, or financial problems. In patients with serial lung function data, the rate of decline in the forced vital capacity was significantly reduced after the combination therapy. In the matched analysis, the combination group had a higher incidence of diarrhea than the monotherapy group without an increase in serious adverse events; however, the two groups had similar changes in forced vital capacity (FVC). Conclusion: The combination of pirfenidone and nintedanib in patients with IPF has the potential to reduce the rate of FVC decline. However, in the matched analysis, FVC decline was comparable between the patients on combination therapy and those on monotherapy. The incidence of certain adverse events, particularly diarrhea, was higher with combination therapy, but serious adverse events were similar between the groups.

Incidence and risk factors associated with progression to severe pneumonia among adults with non-severe Legionella pneumonia.

BACKGROUND: Legionella species are important causative organisms of severe pneumonia. However, data are limited on predictors of progression to severe Legionella pneumonia (LP). Therefore, the risk factors for LP progression from non-severe to the severe form were investigated in the present study. METHODS: This was a retrospective cohort study that included adult LP patients admitted to a 2,700-bed referral center between January 2005 and December 2019. RESULTS: A total of 155 patients were identified during the study period; 58 patients (37.4%) initially presented with severe pneumonia and 97 (62.6%) patients with non-severe pneumonia. Among the 97 patients, 28 (28.9%) developed severe pneumonia during hospitalization and 69 patients (71.1%) recovered without progression to severe pneumonia. Multivariate logistic regression analysis showed platelet count ≤150,000/mm3 (odds ratio [OR], 2.923; 95% confidence interval [CI], 1.100-8.105; P=0.034) and delayed antibiotic treatment >1 day (OR, 3.092; 95% CI, 1.167-8.727; P=0.026) were significant independent factors associated with progression to severe pneumonia. CONCLUSIONS: A low platelet count and delayed antibiotic treatment were significantly associated with the progression of non-severe LP to severe LP.

Sarcoid-like reaction in patients with malignant tumors: Long-term clinical course and outcomes.

Background: The development of non-caseating epithelioid cell granulomas in cancer patients who do not fulfill the systemic sarcoidosis criteria is termed sarcoid-like reaction (SLR). Little is known about this condition's natural course and impact on the prognosis of malignancy. We aimed to investigate the natural course and prognostic value of cancer-associated SLR. Methods: Clinical data were retrospectively analyzed in 32 patients with biopsy-proven cancer-associated SLR. Among patients with non-small cell lung cancer (NSCLC), SLR cases (n = 8) were matched with non-SLR cases (n = 78) for survival analysis. Results: Among the included patients, the mean age was 59.7 years, and 68.8% were female. The median follow-up period was 35.6 months [interquartile range (IQR): 14.0-61.4 months]. Of all the included malignancies (n = 32), breast cancer (25.0%) and NSCLC (25.0%) were the most common, with stage I being the most frequent tumor stage (59.4%). During follow-up, SLR progression to overt sarcoidosis was not observed. In the 28 patients with available follow-up computed tomography images (median interval: 24.9 months; IQR: 14.4-41.7), 4 patients received corticosteroids (n = 4), resulting to a decrease of SLR lesions. Meanwhile, among those who did not receive treatment (n = 24), the extent of SLR decreased or did not change in 85.7% of them, whereas 3.6% had increased SLR extent. Furthermore, among patients with NSCLC, SLR was not associated with overall survival [hazard ratio (HR) = 1.28, 95% confidence interval (CI): 0.02-67.71, P = 0.882] and recurrence of malignancy (HR = 1.27, 95% CI 0.21-7.51, P = 0.793) in the Cox proportional hazard regression model. Conclusions: During the follow-up of cancer-related SLR, we found no further evidence for systemic sarcoidosis, and most of the lesions decreased or did not change. Development of SLR was also not associated with overall survival or disease-free survival in patients with NSCLC.

Foreign body aspirations in dental clinics: a narrative review.

Foreign body aspiration can produce a medical emergency. Obstruction of the airways can be life-threatening, and complications may develop in less-severe cases if it is left untreated. Although it is more prevalent in children by approximately three times, adults can still experience it, and it is more frequently related to healthcare in adults. Objects used in dental treatment are usually placed in the oral cavity and can be ingested or inhaled by accident. Dental treatment has been identified as an important cause of the misplacement of foreign bodies in the airway. However, few reports have been published on dentistry-related foreign body aspiration. This paper discusses the disease course, management, and clinical outcomes of foreign body aspiration, especially those associated with dentistry. The patient must be examined for respiratory distress. If the patient is unstable, urgent airway management and the maneuvers for removal should be performed. Radiographs and computed tomography can help identify and locate the object. The treatment of choice is often bronchoscopy, and both flexible and rigid endoscopes can be used depending on the situation. Preventive measures need to be implemented to avoid inhalation accidents given the potential consequences. Though the incidence is rare, healthcare levels need to be enhanced to avert morbidity and mortality. Radiological evaluation and bronchoscopy are vital for management.

Comparative efficacy of inhalers in mild-to-moderate asthma: systematic review and network meta-analysis.

The comparative effectiveness of different inhaler therapies in mild-to-moderate asthma remains unclear. To assess this, we performed a systematic review and network meta-analysis of randomized controlled trials on the use of inhalers for mild-to-moderate asthma by searching PubMed, Cochrane, and Embase. A total of 29 trials including 43,515 patients and 12 types of inhaler therapies were included. For the prevention of severe and moderate-to-severe exacerbations, inhaled corticosteroid (ICS)/long-acting ß2-agonist (LABA) as maintenance and reliever (SMART) showed the highest rank for effectiveness. As-needed ICS/LABA or short-acting ß2-agonist (SABA) was similar to low-dose ICS and superior to as-needed SABA or LABA for the prevention of severe and moderate-severe exacerbations. As for lung function (FEV1), low-dose ICS/LABA had the highest rank; as-needed ICS/LABA was inferior to regular low-dose ICS but superior to placebo. Higher-dose ICS had a superior effect on the Asthma Control Questionnaire (ACQ) scores, and as-needed ICS/LABA and as-needed SABA or LABA had lower ranks in p-rankogram than did the regular use of low-dose ICS. As-needed ICS with LABA or SABA was more effective than a similar dose of regular ICS for preventing exacerbation in mild-to-moderate asthma. As-needed ICS showed some weakness in improving lung function and controlling asthma symptoms.

The Impact of Air Pollutants and Meteorological Factors on Chronic Obstructive Pulmonary Disease Exacerbations: A Nationwide Study.

Rationale: Chronic obstructive lung disease (COPD) is a chronic progressive disease. Although smoking is the most important risk factor, 30% of patients with COPD are never-smokers, and environmental agents are also influential. The effects of air pollutants and meteorological factors on COPD exacerbations have not been studied extensively. Objectives: We aimed to investigate the air pollutants and meteorological factors that impact the incidence of COPD exacerbations. Methods: We obtained clinical data of COPD exacerbation cases from The National Health Insurance Service and merged it with 24-hour average values of air pollutants and meteorological factors from national databases. Patients who reside in eight metropolitan cities, where observatory stations are densely located, were selected for analysis. Results: In 1,404,505 patients with COPD between 2013 and 2018, 15,282 COPD exacerbations leading to hospitalization or emergency room visits were identified. Among the various air pollutants and meteorological factors, particulate matter ⩽2.5 µm in aerodynamic diameter (PM2.5), particulate matter ⩽10 µm in aerodynamic diameter (PM10), NO2, SO2, CO, O3, average temperature, and diurnal temperature range (DTR) were associated with COPD exacerbations. Generalized additive mode model analysis with cubic splines showed an inverted U-shaped relationship with PM2.5, PM10, CO, NO2, SO2, O3, DTR, and humidity, whereas it displayed a U-shaped pattern with the average temperature. Distinct patterns were found from 2015-2016 to 2017-2018. Conclusions: PM2.5, PM10, CO, NO2, O3, SO2, average temperature, humidity, and DTR affected the incidence of COPD exacerbations in various patterns, up to 10 lag days.

Behavioral interventions to reduce particulate matter exposure in patients with COPD.

INTRODUCTION: Chronic obstructive pulmonary disease (COPD) is commonly affected by particulate matter (PM) exposure. In this study, we aimed to evaluate whether behavioral interventions to reduce PM exposure improve clinical outcomes in patients with COPD. METHODS: A multicenter randomized controlled trial will be conducted involving 120 participants recruited from 3 hospitals in the capital region of the Republic of Korea. Patients aged 40 to 80 years with a diagnosis of COPD and a forced expiratory volume at 1 s <80% of the predicted value are eligible for inclusion. The participants will be randomized to either the intervention group or the usual care group (2:1). The behavioral interventions will comprise the following activities: checking air quality forecast; operating indoor air cleaners and regular check-ups of filters; ventilating the home regularly by opening windows; adhering to inhaler treatment; and refraining from going out on high air pollution days. "Internet-of-things"-based, gravimetric, and light-scattering methods will be used to measure indoor and outdoor PM concentrations. To estimate the degree of individual PM exposure, a time-activity diary and land use regression modeling will be used. The efficacy of the behavioral interventions on the following outcomes will be analyzed: amount of PM exposure, changes in forced expiratory volume at 1 s from the baseline, changes in respiratory symptoms and quality of life, risks of exacerbation, hospitalization, and death. DISCUSSION: Given the harmful effect of air pollutants, individual-level interventions to reduce exposure may be significant. However, there is a lack of evidence on how effective such interventions are to date. This study will be able to provide physicians and patients with evidence-based strategies to reduce PM exposure in daily life. TRIAL REGISTRATION NUMBER: NCT04878367.

Does the Risk of Metabolic Syndrome Increase in Thyroid Cancer Survivors?

BACKGROUND: The steep rise in thyroid cancer observed in recent decades has caused an increase in the population of long-term thyroid cancer survivors. Other than recurrences of cancer, the long-term health consequences of surviving thyroid cancer, particularly metabolic syndrome, have not yet been determined. The aim of this study was to estimate the risk of metabolic syndrome in thyroid cancer survivors. MATERIALS AND METHODS: Population-based data from the Korean National Health and Nutrition Examination Survey (KNHANES) were used for the analysis. The data of KNHANES IV-VI from 2007-2014 were obtained. After excluding subjects who were under 19 years old, whose fasting interval was less than 8 hours, and whose data for predefined variables including metabolic syndrome components were incomplete, 34,347 subjects were analyzed. The incidence of metabolic syndrome and its components were evaluated in three groups: subjects with no history of thyroid cancer, subjects diagnosed with thyroid cancer within 3 years of the survey date, and subjects diagnosed more than 3 years before the survey date. RESULTS: Thyroid cancer diagnoses were made within 3 years of the survey date for 95 subjects (group 1, short-term survivors) and more than 3 years earlier than the survey date for 60 subjects (group 2, long-term survivors). Metabolic syndrome was frequently observed with clinical significance (odds ratio [OR] 1.986 [95% confidence interval [CI] 1.0-3.70], p = 0.030) in short-term survivors compared with subjects with no thyroid cancer history. Risks for having high blood pressure and high fasting glucose were estimated to be higher in the short-term survivor group (OR 2.115 [CI 1.23-3.64], p = 0.006 and OR 1.792 [CI 1.03-3.11], p = 0.038, respectively). No significant associations were noticed in the long-term survivor group when compared with the group with no thyroid cancer history. CONCLUSION: Risks for metabolic syndrome, especially high blood pressure and high fasting glucose, were increased in short-term survivors of thyroid cancer but not in long-term survivors when compared with subjects with no history of thyroid cancer.

Role of co-vapors in vapor deposition polymerization.

Polypyrrole (PPy)/cellulose (PPCL) composite papers were fabricated by vapor phase polymerization. Importantly, the vapor-phase deposition of PPy onto cellulose was assisted by employing different co-vapors namely methanol, ethanol, benzene, water, toluene and hexane, in addition to pyrrole. The resulting PPCL papers possessed high mechanical flexibility, large surface-to-volume ratio, and good redox properties. Their main properties were highly influenced by the nature of the co-vaporized solvent. The morphology and oxidation level of deposited PPy were tuned by employing co-vapors during the polymerization, which in turn led to change in the electrochemical properties of the PPCL papers. When methanol and ethanol were used as co-vapors, the conductivities of PPCL papers were found to have improved five times, which was likely due to the enhanced orientation of PPy chain by the polar co-vapors with high dipole moment. The specific capacitance of PPCL papers obtained using benzene, toluene, water and hexane co-vapors was higher than those of the others, which is attributed to the enlarged effective surface area of the electrode material. The results indicate that the judicious choice and combination of co-vapors in vapor-deposition polymerization (VDP) offers the possibility of tuning the morphological, electrical, and electrochemical properties of deposited conducting polymers.

Synergistic effect of xylitol and ursolic acid combination on oral biofilms.

OBJECTIVES: This study was designed to evaluate the synergistic antibacterial effect of xylitol and ursolic acid (UA) against oral biofilms in vitro. MATERIALS AND METHODS: S. mutans UA 159 (wild type), S. mutans KCOM 1207, KCOM 1128 and S. sobrinus ATCC 33478 were used. The susceptibility of S. mutans to UA and xylitol was evaluated using a broth microdilution method. Based on the results, combined susceptibility was evaluated using optimal inhibitory combinations (OIC), optimal bactericidal combinations (OBC), and fractional inhibitory concentrations (FIC). The anti-biofilm activity of xylitol and UA on Streptococcus spp. was evaluated by growing cells in 24-well polystyrene microtiter plates for the biofilm assay. Significant mean differences among experimental groups were determined by Fisher's Least Significant Difference (p < 0.05). RESULTS: The synergistic interactions between xylitol and UA were observed against all tested strains, showing the FICs < 1. The combined treatment of xylitol and UA inhibited the biofilm formation significantly and also prevented pH decline to critical value of 5.5 effectively. The biofilm disassembly was substantially influenced by different age of biofilm when exposed to the combined treatment of xylitol and UA. Comparing to the single strain, relatively higher concentration of xylitol and UA was needed for inhibiting and disassembling biofilm formed by a mixed culture of S. mutans 159 and S. sobrinus 33478. CONCLUSIONS: This study demonstrated that xylitol and UA, synergistic inhibitors, can be a potential agent for enhancing the antimicrobial and anti-biofilm efficacy against S. mutans and S. sobrinus in the oral environment.

Anisotropic growth control of polyaniline nanostructures and their morphology-dependent electrochemical characteristics.

Polyaniline (PANI) is one of the most widely investigated conducting polymers and is considered to be of practical use for many future applications. Here, we first demonstrate that the anisotropic growth of PANI at the nanometer scale can be kinetically controlled by employing a polymeric stabilizer, poly(N-vinylpyrrolidone). The polymerization rate became slower in the presence of the stabilizer (the rate constants calculated at the initial stage decreased with increasing concentration of the stabilizer), yielding PANI nanostructures with lower aspect ratios. Therefore, it is believed that the stabilizer sterically restricts the directional fiber growth mechanism governing PANI chain growth in aqueous solution. Three PANI nanostructures, specifically nanospheres, nanorods, and nanofibers, were fabricated and their oxidation/protonation levels were investigated systematically. It was found that the nanofibers had the most outstanding oxidation/protonation level accompanied by structural ordering (note that the only difference between the polymerization conditions in each case was the concentration of the stabilizer). We also examine the electrochemical properties of PANI nanostructure electrodes in three-electrode and two-electrode (actual capacitor cell) configurations. The intrinsic charge-transport ability of individual nanostructures strongly affected the electrochemical properties of the electrodes. Briefly, the nanofiber electrode had faster electrode kinetics and better capacitance than the nanorods and nanospheres. Lastly, an extrinsic factor, the interparticle contact resistance, also turned out to noticeably influence the capacitances of the electrodes.

Vertical alveolar ridge augmentation using autogenous bone grafts and platelet-enriched fibrin glue with simultaneous implant placement.

OBJECTIVE: The aim of this study was to evaluate the combined use of autogenous bone and platelet-enriched fibrin glue as grafting material for vertical alveolar ridge augmentation with simultaneous implant placement in a canine alveolar ridge defect model. STUDY DESIGN: In 6 mongrel dogs, bilateral vertical alveolar ridge defects were created in the mandible. After 3 months of healing, 2 dental implants were placed in each defect of the mandible, creating 6-mm supra-alveolar peri-implant defects. The 2 implants per defect were subjected to surgical treatments involving either a combination of autogenous bone grafts and platelet-enriched fibrin glue, or a conventional flap procedure only (control). After a healing period of 6 months, the dogs were humanely killed for histological and histometric analyses. RESULTS: Implant placement alone produced limited vertical alveolar height (0.6 +/- 0.4 mm). However, alveolar augmentation including a combination of autogenous bone grafts and platelet-enriched fibrin glue with simultaneous implant placement resulted in alveolar ridge augmentation amounting to 4.2 +/- 1.0 mm, comprising 63% of the defect height. New bone-implant contact was 40.5% in the defects treated with combined autogenous bone grafts and platelet-enriched fibrin glue, and was 48.4% in the resident bone; this difference was not statistically significant. CONCLUSION: The present study demonstrates that vertical alveolar ridge augmentation using autogenous bone grafts and platelet-enriched fibrin glue with simultaneous implant placement might effectively increase vertical alveolar ridge height and allow for an acceptable level of osseointegration.