Association between lead exposure and increased risk of bronchial asthma in Korean adolescents

PURPOSE: Several studies have reported an association between lead exposure and increased risk of allergic sensitization and asthma. According to the Centers for Disease Control and Prevention guidelines, An elevated blood lead level (BLL) is defined as a BLL of ≥5 µg/dL. However, no safe BLL has been identified, and it is controversial whether a BLL of <5 µg/dL affects the risk of asthma. METHODS: We examined asthma prevalences and BLLs using data from the 2010–2013 Korea National Health and Nutrition Examination Survey (KNHANES), which was a cross-sectional survey of 1,478 adolescence (aged 10–19 years) throughout the country. The adjusted odds ratios (ORs) (with 95% confidence intervals [CIs]) for the prevalence of asthma in adolescence with elevated BLLs were calculated by complex samples multivariate logistic regression analysis. The presence of asthma was based on self-reported, physician-diagnosed asthma in the Health Interview Surveys. RESULTS: The mean of total BLLs was 1.33 µg/dL. Overall, 5.1% (n=71) of the subjects were physician diagnosed asthma. In the model controlling for population characteristics, the adjusted odds ratio for asthma per 1 µg/dL increase in blood lead was 1.94, 95% CI (1.06, 3.57), and stronger associations were observed among boys (adjusted OR, 2.31; 95% CI, [1.18, 4.51]). The group of BLL≥2 µg/dL was associated with an OR of 2.84 (95% CI, 1.06, 7.63) for asthma, after adjusting for potential confounding factors in boys. CONCLUSION: Our results suggest an association between total BLLs and asthma in Korean adolescent boys, although confirmation is warranted in further prospective studies.

Biomarkers for Recurrent Wheezing and Asthma in Preschool Children

Wheezing is one of the characteristic symptoms of asthma, but all preschool children with wheezing are not diagnosed with asthma. Preschool children are not cooperative enough to participate in spirometry and invasive tests. Thus, there is no conventional method to diagnose asthma in preschool children. We reviewed studies on non-invasive biomarkers for assessing asthma in preschool children. Specimens that can be easily obtained by non-invasive methods are blood, exhaled breath and urine. Eosinophils, eosinophil cationic protein and eosinophil-derived neurotoxin (EDN) in blood are helpful in evaluating eosinophilic inflammation of the airways. Exhaled breath contains nitric oxide, volatile organic compounds, various cytokines and mediators as analytical components. Fraction of exhaled nitric oxide has been used to assess the degree of eosinophil inflammation and has been standardized in school-age children and adults, but not yet in preschool children. Exhaled breath condensate (EBC) pH and various cytokines/mediators that are detected in EBC seem to be promising biomarkers for assessing asthma, but need more standardization and validation. There are several biomarkers useful for assessing asthma, but none are ideal. Some biomarkers need standardized methods of obtaining samples from uncooperative preschool children for clinical use and require sufficient validation. Recently, another activated eosinophil marker, serum EDN, has shown promising results as a biomarker for recurrent wheezing and asthma in preschool children.

Seasonal patterns and etiologies of croup in children during the period 2010–2015: A multicenter retrospective study

PURPOSE: Croup is known to have epidemics in seasonal and biennial trends, and to be strongly associated with epidemics of parainfluenza virus. However, seasonal and annual epidemics of croup have not been clearly reported in Korea. This study aimed to examine the seasonal/annual patterns and etiologies of childhood croup in Korea during a consecutive 6-year period. METHODS: Pediatric croup data were collected from 23 centers in Korea from 1 January 2010 to 31 December 2015. Electronic medical records, including multiplex reverse transcription polymerase chain reaction (RT-PCR) results, demographics and clinical information were cross-sectionally reviewed and analyzed. RESULTS: Overall, 2,598 childhood croup patients requiring hospitalization were identified during the study period. Among them, a total of 927 who underwent RT-PCR were included in the analysis. Males (61.5%) predominated, and most (63.0%) of them were younger than 2 years of age (median, 19 months; interquartile range, 11–31 months). Peak hospitalization occurred in 2010 and 2012 in even-numbered years, and parainfluenza virus (PIV, 39.7%) was the most common cause of childhood croup requiring hospitalization, followed by respiratory syncytial virus (14.9%), human rhinovirus (12.5%), Mycoplasma pneumonaie (10.6%), and human coronavirus (7.3%). CONCLUSION: It is concluded that croup hospitalization has a biennial pattern in even-numbered years. PIV may be the most common cause of childhood croup; however, croup epidemics could be attributed to other viruses.

Comparison of clinical severity between single- and coinfections of respiratory syncytial virus and influenza virus with common respiratory viruses

PURPOSE: Multiple virus infections may affect clinical severity. We investigated the effect of coinfection of respiratory syncytial virus (RSV) and influenza virus with other respiratory viruses on clinical severity. METHODS: Data from 634 samples of a single tertiary hospital between September 2014 and April 2015 were analyzed for clinical characteristics (fever duration and O2 need, steroid use, and ICU care) between single infection and coinfection of RSV (n=290) and influenza virus (n=74) with 16 common respiratory viruses from hospitalized children. RESULTS: The RSV coinfection group (n=109) (3.1±2.7 days) showed significantly longer fever duration than the RSV single infection group (n=181) (2.6±2.6 days) (P=0.04), while there was no difference in O2 need, steroid use or ICU care in the 2 groups. The influenza coinfection group (n=38) showed significantly higher O2 need than the influenza single infection group (n=36) (21.1% vs. 5.6%, P=0.05), while there was no difference in fever duration between the 2 groups. CONCLUSION: The results indicate that RSV and Influenza coinfections can increase clinical severity and that the severity may be influenced by the nature of coinfecting viruses.

Serum Levels of Eosinophil-Derived Neurotoxin: A Biomarker for Asthma Severity in Adult Asthmatics

PURPOSE: Eosinophilic inflammation is a key component of severe asthma (SA). However, there has been no reliable serum biomarker for the eosinophilic inflammation of SA. We hypothesized that serum eosinophil-derived neurotoxin (EDN) could predict the eosinophilic inflammation of SA in adult asthmatics. METHODS: Severe asthmatics (n = 235), nonsevere asthmatics (n = 898), and healthy controls (n = 125) were enrolled from Ajou University Hospital, South Korea. The serum levels of EDN and periostin were measured by enzyme-linked immunosorbent assay and compared between severe and nonsevere asthmatics. Their associations with total eosinophil count (TEC) and clinical parameters were evaluated; clinical validation of the K-EDN kit for the measurement of serum EDN was evaluated. RESULTS: Severe asthmatics were older and had longer disease duration with significantly lower levels of forced expiratory volume in 1 second and methacholine PC20 than nonsevere asthmatics. Significant differences were found in TEC or sputum eosinophil count (%) between the groups. The serum levels of EDN and periostin were significantly higher in severe asthmatics than in nonsevere asthmatics and in healthy controls (all P < 0.05). Although significant correlations were found between serum EDN levels measured by the 2 kits (ρ = 0.545, P < 0.0001), higher correlation coefficients between serum EDN levels measured by the K-EDN kit and TEC were higher (ρ = 0.358, P < 0.0001) than those between serum EDN levels measured by the MBL kit and TEC (ρ = 0.319, P < 0.0001) or serum periostin level (ρ = 0.222, P < 0.0001). Multivariate regression analysis demonstrated that serum EDN levels measured by the K-EDN kit predicted the phenotype of SA (P = 0.003), while 2 other biomarkers did not. CONCLUSIONS: The serum EDN level may be a useful biomarker for assessing asthma severity in adult asthmatics.

Multicenter Adherence Study of Asthma Medication for Children in Korea

PURPOSE: Adherence is a major component of successful medical treatment. However, non-adherence remains a barrier to effective delivery of healthcare worldwide. METHODS: Twenty healthcare facilities (secondary or tertiary hospitals) belonging to the Korean Academy of Pediatric Allergy and Respiratory Diseases (KAPARD) participated. Questionnaires were given to patients currently receiving treatment in the form of inhalant useor oral intake or transdermal patch for mild to moderate asthma. RESULTS: A total of 1,838 patients responded to the questionnaire. Mean age was 5.98 ± 3.79 years (range: 0-18 years). With help from their caregivers, the percentage of patients that answered “taking as prescribed” was 38.04% for inhalant users, 50.09% for oral medication users and 67.42% for transdermal users. Transdermal patch users had significantly greater adherence compared to the other 2 groups (P < 0.001). The 34.15% of inhalant users, 70.33% of oral medication users and 93.00% of transdermal patch users felt that their medication delivery system was “Easy” or “Very easy” to use (P < 0.001). “Method of administration” was deemed to be the most difficult part of the treatment regimen to follow, and 76.7% of patients preferred once-daily administration (i.e., “Frequency of administration”). CONCLUSIONS: Asthma medication adherence in young children was found to be better in the transdermal patch group. This may be due to requiring fewer doses and easy to follow instructions. From an adherence point of view, the transdermal patch seems more useful for long-term asthma control in children compared to oral or inhaled medicine.

Montelukast Reduces Serum Levels of Eosinophil-Derived Neurotoxin in Preschool Asthma

PURPOSE: Several markers for eosinophilic inflammation have been proposed to predict response to asthma treatment. However, definitive criteria for treatment decisions have not yet been established. We investigate a potentially useful relatively non-invasive biomarker, eosinophil-derived neurotoxin (EDN), to predict favorable responses to budesonide or montelukast, common treatment for children with asthma. METHODS: Young children (1 to 6 years old) were enrolled in this randomized, parallel, 2-group, open-label trial. Criteria for eligibility included: 1) being symptomatic during the run-in period; and 2) having a serum EDN (sEDN) level ≥ 53 ng/mL, with positive specific immunoglobulin E to house dust mite. Eligible patients were randomly placed into 2 groups: the BIS group received budesonide inhalation suspension (BIS) 0.5 mg once daily; the MONT group received montelukast 4 mg once daily. Ineligible patients were invited to receive montelukast 4 mg once daily (OBS group). Treatment period was 12 weeks. RESULTS: Asthma control days increased significantly in the BIS and MONT groups (P < 0.000) over the 12-week study period. There was no significant change in sEDN in the BIS group but there was a significant decrease in the MONT group (P < 0.000). Patients in the OBS group with high EDN levels (< 53 ng/mL) showed a significant decrease due to MONT treatment (P = 0.023). Rescue medication usage significantly decreased in the BIS and MONT groups (P < 0.000). CONCLUSIONS: EDN is a useful relatively non-invasive biomarker for predicting responses to montelukast and budesonide treatment of preschool children with beta2-agonist responsive recurrent wheeze and multiple-trigger wheeze (Trial registry at UMIN Clinical Trials Registry, UMIN000008335).

Proper allergen selection for serum specific IgE test in children

Identifying allergic sensitization is important for the proper diagnosis and management of allergic diseases. Skin prick testing and measuring serum specific IgE antibodies are standard tests to confirm allergic sensitization. Skin prick testing has many advantages, but it is difficult to perform on young children. Serum specific IgE can be easily performed on young children, but it can be performed only up to 12 antigens in patients younger than 6 years due to insurance coverage. Therefore, it is important to select appropriate antigens for the patients. Appropriate allergens may vary depending on the patient's age, accompanying disease, and residential area, so that detailed history taking is essential for proper allergen selection. In this review, we will discuss considerations for selecting appropriate allergens for clinicians when performing an allergy test on difficult-to-test children under 6 years of age.

Viral Infections and Associated Factors That Promote Acute Exacerbations of Asthma

Despite asthma being the most common chronic childhood ailment, there is still much to learn about the disease. Early childhood infections with well-known or emerging viruses can lay the pathophysiologic framework for asthma development and exacerbation later in life, which may be due partly to alteration of the airway microbiome. Once asthma is established, acute exacerbations are usually associated with infections with respiratory viruses, such as rhinoviruses (RVs). Once again, there are bidirectional interactions between viruses and airway bacteria that appear to influence the severity of illness and the likelihood of exacerbation. Studies employing recent advances in viral and bacterial identification analytic techniques will clarify these new concepts and may provide the basis for new treatments or prevention or respiratory infection-associated exacerbation. This paper is a review of the associations among respiratory viruses, bacteria, inflammatory mechanisms, and asthma exacerbation.

Comparison of nasal cytokine profiles of human metapneumovirus and respiratory syncytial virus

BACKGROUND: Human metapneumovirus (hMPV) and respiratory syncytial virus (RSV) share some epidemiological and clinical characteristics; however, few studies have examined the mechanisms by which these viruses induce airway inflammation. OBJECTIVE: This study was undertaken to compare cytokine profiles in hMPV and RSV patients to investigate possible differences in inflammatory pathways. METHODS: Nasopharyngeal aspirate specimens were collected from 1,008 pediatric patients hospitalized for acute lower respiratory tract infection with wheezing and 20 normal healthy controls. Patients were tested for 7 common respiratory viruses then divided into hMPV (n = 35) and RSV groups (n = 67). T helper (Th) 1 (interferon [IFN]-γ), Th2 (interleukin [IL]-4, eotaxin) and Th17 (IL-1β, IL-6) cytokine profiles were analyzed in the 3 groups. RESULTS: IFN-γ and IL-2 levels were significantly increased in the hMPV and RSV groups compared to the control group (p < 0.0001 and p < 0.0001, respectively). IL-4 levels were significantly higher in the RSV group compared to the hMPV and control groups (p = 0.0003 and p < 0.0001, respectively). Eotaxin levels showed a tendency to be higher in the RSV group compared to the hMPV group (p = 0.0580), and significantly higher compared to the control group (p < 0.0001). IL-1β levels were significantly higher in the hMPV compared to the RSV group (p < 0.0001), and IL-6 levels were significantly higher in the hMPV group compared to the control group (p < 0.0001). CONCLUSION: Our results suggest that hMPV and RSV have different inflammatory mechanisms. hMPV induces airway inflammation by the Th17 pathway through release of IL-1β and IL-6, whereas RSV acts through the Th2 pathway.

Eosinophil-derived neurotoxin: a novel biomarker for diagnosis and monitoring of asthma / 소아과

Asthma is associated with increased levels of eosinophils in tissues, body fluids, and bone marrow. Elevated levels of eosinophil-derived neurotoxin (EDN) and eosinophil cationic protein (ECP) have been noted in asthma patients. Higher levels of EDN and ECP are also associated with exacerbated asthmatic conditions. Thus, EDN, along with ECP, may aid the diagnosis and monitoring of asthma. Several groups have suggested that EDN is more useful than ECP in evaluating disease severity. This may partially be because of the recoverability of EDN (not sticky, 100% recovery rate), as ECP is a sticky and more highly charged protein. In terms of clinical utility, EDN level is a more accurate biomarker than ECP when analyzing the underlying pathophysiology of asthma. As a monitoring tool, EDN has shown good results in children with asthma as well as other allergic diseases. In children too young to fully participate in lung function tests, EDN levels may be useful as an alter native measurement of eosinophilic inflammation. EDN can also be used in adult patients and in multiple specimen types (e.g., serum, sputum, bronchoalveolar lavage fluid, and nasal lavage fluid). These results are repeatable and reproducible. In conclusion, EDN may be a novel biomarker for the diagnosis, treatment, and monitoring of asthma/allergic disease.

Infection, eosinophilia and childhood asthma

There is a growing list of viruses and bacteria associated with wheezing illness and asthma. It is well known that a few of these pathogens are strongly associated with wheezing illness and asthma exacerbations. What is not known is if early childhood infections with these pathogens cause asthma, and, if so, exactly what are the pathophysiologic mechanisms behind its development. The current consensus is respiratory infection works together with allergy to produce the immune and physiologic conditions necessary for asthma diasthesis. One link between respiratory infection and asthma may be the eosinophil, a cell that plays prominently in asthma and allergy, but can also be found in the body in response to infection. In turn, the eosinophil and its associated products may be novel therapeutic targets, or at the very least used to elucidate the complex pathophysiologic pathways of asthma and other respiratory illnesses. Together or separately, they can also be used for diagnosis, treatment and monitoring. The optimal care of a patient must take into consideration not only symptoms, but also the underlying disease mechanisms.

Predisposing Factors Associated With Chronic and Recurrent Rhinosinusitis in Childhood

PURPOSE: There is currently no information regarding predisposing factors for chronic and recurrent rhinosinusitis (RS), although these are considered to be multifactorial in origin, and allergic diseases contribute to their pathogenesis. We evaluated the predisposing factors that may be associated with chronic and recurrent RS. METHODS: In this prospective study, we examined patients with RS younger than 13 years of age, diagnosed with RS at six tertiary referral hospitals in Korea between October and December, 2006. Demographic and clinical data related to RS were recorded and analyzed. RESULTS: In total, 296 patients were recruited. Acute RS was the most frequent type: 56.4% of the patients had acute RS. The prevalences of other types of RS, in descending order, were chronic RS (18.9%), subacute RS (13.2%), and recurrent RS (11.5%). Factors associated with recurrent RS were similar to those of chronic RS. Patients with chronic and recurrent RS were significantly older than those with acute and subacute RS. The prevalences of allergic rhinitis, atopy, and asthma were significantly higher in patients with chronic and recurrent RS than those with acute and subacute RS. CONCLUSIONS: An association between atopy and chronic/recurrent RS, compared to acute and subacute RS, suggests a possible causal link.

Comparison of Clinical Manifestation and Laboratory Findings between H1N1 and Influenza B Infection / 소아알레르기및호흡기학회지

PURPOSE: Influenza virus is one of the most important viruses that cause the respiratory infection seasonally. In April 2009, H1N1 was detected in America and Mexico and then there was pandemic in Korea. We investigated the difference of clinical and laboratory findings between the infections of H1N1 and Influenza B. METHODS: We have retrospectively studied the patients under age of 15 years who visited Inje University Sanggye Paik Hospital from August 2009 to April 2010. Evaluation for influenza infection was performed by rapid antigen test or multiplex reverse transcriptase polymerase chain reaction. Complete blood count with differential counts, C-reactive protein and chest X-ray were checked. RESULTS: Enrolled patients were 2,226 in H1N1-infected group and 288 in influenza B-infected group. Seasonal variation was that H1N1 in autumn and winter but influenza B in spring. The male-to-female sex ratio was same as 1.23 in each group. The mean age of H1N1-infected group was higher than influenza B-infected group (P<0.001). Fever was developed similarly in both groups (P=0.114). However, cough, sputum, rhinorrhea, vomiting, diarrhea, and headache were more prevalent in influenza B infection compared to H1N1 infection (P<0.001). Pneumonia development and admission rate were higher in influenza B infection compared to H1N1 infection (P<0.001, respectively). CONCLUSION: Although H1N1 infection spread rapidly, H1N1 caused not so severe symptoms than influenza B. Because of the possibility that influenza epidemic will develop repeatedly in the future, we need to evaluate more about different characteristics depending on the virus subtype and prepare for them.

The effect of the strength and wetting characteristics of Bis-GMA/TEGDMA-based adhesives on the bond strength to dentin / 대한치과보존학회지

OBJECTIVES: This study investigated the effect of the strength and wetting characteristics of adhesives on the bond strength to dentin. The experimental adhesives containing various ratios of hydrophobic, low-viscosity Bis-M-GMA, with Bis-GMA and TEGDMA, were made and evaluated on the mechanical properties and bond strength to dentin. MATERIALS AND METHODS: Five experimental adhesives formulated with various Bis-GMA/Bis-M-GMA/TEGDMA ratios were evaluated on their viscosity, degree of conversion (DC), flexural strength (FS), and microtensile bond strength (MTBS). The bonded interfaces were evaluated with SEM and the solubility parameter was calculated to understand the wetting characteristics of the adhesives. RESULTS: Although there were no significant differences in the DC between the experimental adhesives at 48 hr after curing (p > 0.05), the experimental adhesives that did not contain Bis-GMA exhibited a lower FS than did those containing Bis-GMA (p < 0.05). The experimental adhesives that had very little to no TEGDMA showed significantly lower MTBS than did those containing a higher content of TEGDMA (p < 0.05). The formers exhibited gaps at the interface between the adhesive layer and the hybrid layer. The solubility parameter of TEGDMA approximated those of the components of the primed dentin, rather than Bis-GMA and Bis-M-GMA. CONCLUSIONS: To achieve a good dentin bond, a strong base monomer, such as Bis-GMA, cannot be completely replaced by Bis-M-GMA for maintaining mechanical strength. For compatible copolymerization between the adhesive and the primed dentin as well as dense cross-linking of the adhesive layer, at least 30% fraction of TEGDMA is also needed.

Fatal and Near-fatal Cases of Lower Respiratory Tract Infection with Human Rhinovirus Group A / 소아알레르기및호흡기학회지

Human rhinoviruses (HRV) mostly cause mild and self-limiting upper respiratory tract infections. We report 2 infants with acute respiratory failure requiring mechanical ventilation, 1 of whom deteriorated to death. The causal pathogen was HRV group A confirmed by multiplex-PCR. In Korea, this is the first report of severe respiratory failure caused by HRV group A during the same season.

Outbreak of Swine-Origin Influenza A (H1N1); Experience of a Regional Center in Seoul during a Month, August-September 2009 / 대한임상미생물학회지

BACKGROUND: The aim of this study is to clarify the epidemiology of swine-origin influenza A (H1N1) virus 2009 (S-OIV) during the first month of outbreak at one of influenza clinic in Seoul, Korea. METHODS: We documented the epidemiologic and clinical features of S-OIV-confirmed cases who visited a university hospital in Northeastern Seoul between August 21 and September 20, 2009. Nasopharyngeal swab of patients with acute febrile respiratory illnesses were evaluated with rapid influenza antigen tests and multiplex RT-PCR for S-OIV and seasonal influenza A. RESULTS: A total of 5,322 patients with acute febrile respiratory illnesses were identified at our influenza clinic for the study period. S-OIV was confirmed in 309 patients by RT-PCR. The patients ranged from 2 months to 61 years of age and 189 patients (61.2%) were teenagers. Eighty-one patients had known contact with S-OIV-confirmed patients in schools (N=61), households (N=15), and healthcare facilities (N=3). Frequent symptoms were fever (94.5%), cough (73.1%), sore throat (52.1%), and rhinorrhea (50.5%). Gastrointestinal symptoms were also present in 10 patients (4.9%). Ten patients (4.9%) required hospitalizations. Seventy patients (22.7%) could not take oseltamivir at the first visits, however, all of them recovered without complication. Rapid antigen tests showed the sensitivity of 44.4% (130/294). Patients with positive antigen tests, compared with negative antigen tests, showed higher frequencies of rhinorrhea (60.8% vs 43.3%, P=0.004) and stuffy nose (33.8% vs 20.1%, P=0.012). CONCLUSION: S-OIV infections spread predominately in school-aged children during the early accelerating phase of the outbreak. Rapid influenza antigen tests were correlated with nasal discharge and obstruction.

The L441P Mutation of Cystic Fibrosis Transmembrane conductance Regulator and its Molecular Pathogenic Mechanisms in a Korean Patient with Cystic Fibrosis

Cystic fibrosis (CF) is an autosomal recessive disorder usually found in populations of white Caucasian descent. CF is caused by mutations in the Cystic Fibrosis Transmembrane conductance Regulator (CFTR) gene. A 5-yr-old Korean girl was admitted complaining of coughing and greenish sputum. Chest radiographs and computed tomographic (CT) scan revealed diffuse bronchiectasis in both lungs. The patient had chronic diarrhea and poor weight gain, and the abdominal pancreaticobiliary CT scan revealed atrophy of the pancreas. Finally, CF was confirmed by the repeated analysis of the quantitative pilocarpine iontophoresis test. The chloride concentration of sweat samples taken from both forearms of the pateint was an average of 88.7 mM/L (normal value <40 mM/L). After a comprehensive search for mutations in the CFTR gene, the patient was found to carry the non-synonymous L441P mutation in one allele. Molecular physiologic analysis of the L441P mutation of CFTR revealed that the L441P mutation completely abolished the CFTR Cl- channel activity by disrupting proper protein folding and membrane trafficking of CFTR protein. These results confirmed the pathogenicity of the L441P mutation of CFTR circulating in the Korean population. The possibility of CF should be suspected in patients with chronic bronchiectasis, although the frequency of CF is relatively rare in East Asia.

Clinical and Epidemiological Comparison of Human Metapneumovirus and Respiratory Syncytial Virus in Seoul, Korea, 2003-2008

Human metapneumovirus (HMPV) shares clinical and epidemiological characteristics with well-known respiratory syncytial virus (RSV). The aim of this study was to investigate the clinical and epidemiological differences between HMPV- and RSV-induced wheezing illnesses. A total of 1,008 nasopharyngeal aspirate specimens was collected from 1,008 pediatric patients hospitalized with acute respiratory tract infection at Inje University Sanggye Paik Hospital from December 2003 to April 2008, and tested for seven common respiratory viruses. Conditions classified as wheezing illness were bronchiolitis, reactive airways disease, and bronchial asthma. HMPV caused a significantly lower proportion of wheezing illness when compared to RSV (48.1% vs. 82.2%, P<0.05). HMPV-induced wheezing illness occurred predominantly in older patients when compared to RSV patients (P<0.001). RSV infections peaked in the fall and winter followed by peaks of HMPV infection in winter and spring. Eosinophil counts were significantly higher (P<0.01) in RSV patients when compared to HMPV patients. These results show that human metapneumovirus patients exhibit several different clinical and epidemiological characteristics, such as higher proportion of wheezing illness, age and seasonal incidence, and eosinophil counts, when compared to RSV patients.

The effect of priming etched dentin with solvent on the microtensile bond strength of hydrophobic dentin adhesive / 대한치과보존학회지

Deterioration of long-term dentin adhesion durability is thought to occur by hydrolytic degradation within hydrophilic domains of the adhesive and hybrid layers. This study investigated the hypothesis that priming the collagen network with an organic solvent displace water without collapse and thereby obtain good bond strength with an adhesive made of hydrophobic monomers and organic solvents. Three experimental adhesives were prepared by dissolving two hydrophobic monomers, bisphenol-A-glycidylmethacrylate (Bis-GMA) and triethyleneglycol dimethacrylate (TEGDMA), into acetone, ethanol or methanol. After an etching and rinsing procedure, the adhesives were applied onto either wet dentin surfaces (wet bonding) or dentin surfaces primed with the same solvent (solvent-primed bonding). Microtensile bond strength (MTBS) was measured at 48 hrs, 1 month and after 10,000 times of thermocycles. The bonded interfaces were evaluated using a scanning electron microscope (SEM). Regardless of bonding protocols, well-developed hybrid layers were observed at the bonded interface in most specimens. The highest mean MTBS was observed in the adhesive containing ethanol at 48 hrs. With solvent-primed bonding, increased MTBS tendencies were seen with thermocycling in the adhesives containing ethanol or methanol. However, in the case of wet bonding, no increase in MTBS was observed with aging.