Objective To investigate the relationship between the nanohardness and mierostructure of the dentin and enamel of human teeth. Methods Nano indentation was used to determine the nanohardness of enamel and dentin; TEM and IR were utilized to observe the microstrueture and crystalline characteristic. Results The mean nanohardness of the enamel [( 4. 92 ± 0. 40 ) Gpa]was significantly higher than that of dentin [(1.17 ± 0. 14) Gpa]. A large quantity of hydroxyapatite (HA) crystals and uniform lattice stripe were found in enamel hut not in dentin. Conclusions The difference of nanohardness between enamel and dentin is related to their density, the inorganic morphology and phase structure.

OBJECTIVEWU polyomavirus (WUPyV), a new member of the genus Polyomavirus in the family Polyomaviridae, has been found to be associated with respiratory tract infections recently. But the role of the WUPyV as agents of human disease remains uncertain. We sought to describe the detection and clinical characterization of WUPyV in acute respiratory tract infection in children.

METHODFrom July 2008 through June 2009, nasopharyngeal aspirates were collected from 771 children who were hospitalized with acute respiratory tract infection in Second Affiliated Hospital of Shantou University Medical College, and from 82 asymptomatic children who visited the health checkup clinic. WUPyV was detected by using PCR technology and was identified by using DNA sequencing. All WUPyV-positive specimens were screened for 9 common viruses [influenza A and B, respiratory syncytial virus (RSV), parainfluenza virus (PIV) 1 and 3, human metapneumovirus, human bocavirus, adenovirus and rhinovirus] by using PCR or RT-PCR. The clinical data of WUPyV infection were collected and analyzed.

RESULTIn this study, fifteen of the 771 tested specimens with acute respiratory tract infection were positive for WUPyV, the positive rate was 1.95% and all of the asymptomatic children who visited the health checkup clinic were negative. Of the 15 cases who were positive for the virus, the age range was 2 to 48 (mean 18.8) months, 9 (60%) were male and 6 (40%) were female. WUPyV was the sole virus detected in 9 specimens (60%) from patients with acute respiratory tract infection. WUPyV was associated with the co-infection with another respiratory virus in 6 of 15 (40%) cases, most frequently with RSV (n = 4), followed by adenovirus (n = 1) and rhinovirus (n = 1). The most common clinical findings in the patients with WUPyV were cough, fever and wheezing. The most frequent diagnoses were pneumonia (n = 8), bronchiolitis (n = 4), upper respiratory tract infections (n = 2) and bronchitis (n = 1). A severe case was complicated with viral encephalitis.

CONCLUSIONWUPyV may be a respiratory pathogen because it was the sole virus detected in 9 specimens from patients with respiratory illness and all of the asymptomatic controls were negative. The most common clinical findings are cough and wheezing. Young children may be susceptible to infection with this virus and occasionally the infection with this virus may cause severe disease. More comprehensive and in-depth studies are required to prove the pathogenicity of these viruses.

Child ; Child, Preschool ; Female ; Genes, Viral ; Humans ; Infant ; Infant, Newborn ; Male ; Polymerase Chain Reaction ; Polyomavirus ; genetics ; isolation & purification ; Polyomavirus Infections ; physiopathology ; virology ; Respiratory Tract Infections ; virology

OBJECTIVETo study the characteristics of viral spectrum and clinical features of children in pediatric intensive care unit (PICU).

METHODNasopharyngeal aspirate specimens (NPA) from 349 patients(1 from each) and 130 cerebrospinal fluids (CSF) specimens were collected from children who were admitted to the PICU of Second Affiliated Hospital of Shantou University Medical College. Additional 87 NPA specimens were collected from healthy children for routine examination on the physical examination center, and the clinical data were collected. Multiplex PCR was applied to detect 16 kinds of viruses from NPA and CSF. Fluorescence quantitative PCR was applied to detect 13 viruses from CSF and to analyze the clinical data of positive cases.

RESULTThere were 209 samples (59.9%) of the 349 NPA specimens were positive for viruses, which included 117 cases positive for human rhinovirus (HRV), 60 for respiratory syncytial virus (RSV), 20 for influenza virus A (Inf A), 10 for adenovirus (ADV), 6 for parainfluenza virus type 3(PIV-3), 6 for human Boca virus (HBoV), 5 for influenza virus C(Inf C), 4 for parainfluenza virus type 4(PIV-4), 4 for human coronavirus-HKU1/OC43, 3 for influenza virus B (Inf B), 3 for WU Polyomavirus (WUPyV), 2 parainfluenza virus type 1(PIV-1), 2 human metapneumovirus (HMPV) and 1 human coronavirus-NL63/229E. But none from 87 healthy controls were positive for any respiratory virus. Among the 130 CSF specimens, in 58 cases the diagnosis was viral encephalitis. There were 22 samples (37.9%) among the 58 CSF specimens positive for viruses, which included 14 enterovirus (EV), 3 human cytomegalovirus (HCMV), 2 mumps virus, 1 coxsackie virus A16 (Cox-A16), 1 herpes simplex virus (HSV) and 1 human rhinovirus (HRV). The total positive rate was 63.3% (221/349) . Co-infection by at least 2 viral pathogens under study was observed in 45 of the 349 patients (12.9% of the total number of cases, 20.4% of the positives cases). The commonest pathogens in co-infected samples were WUPyV (100%) and HMPV(100%). The positive rate of virus peaked in the first 6 months of life, the rate in boys were higher than in girls and the peak season was summer. The numbers of none serious cases in the virus positive group were less than those in the virus negative group while the numbers of extremely serious cases in the virus positive group were higher than in the virus negative group.

CONCLUSIONViral pathogen is a major cause of infectious disease in pediatric critical illnesses and virus infection may lead to severe illness.

Acute Disease ; Age Distribution ; Child ; Child, Preschool ; Coinfection ; virology ; Encephalitis, Viral ; epidemiology ; virology ; Female ; Humans ; Infant ; Influenza A virus ; isolation & purification ; Intensive Care Units, Pediatric ; Male ; Polymerase Chain Reaction ; RNA Viruses ; isolation & purification ; Respiratory Syncytial Viruses ; isolation & purification ; Respiratory Tract Infections ; epidemiology ; virology ; Rhinovirus ; isolation & purification ; Virus Diseases ; epidemiology ; virology

Objective To investigate the prevalence and clinical features of human rhinovirus (HRV) infection in hospitalized children with acute respiratory (ARI) in eastern areas of Guangdong province from 2008 to 2010.Methods From Oct.2008 through Sep.2010,nasopharyngeal aspirates were collected prospectively,from hospitalized children with acute lower respiratory tract infection at the Second Hospital,affiliated to the Shantou University Medical College.Multiplex PCR was applied to detect ten kinds of viruses including HRV,RSV in the hospitalized children with respiratory tract infection.Clinical data on HRV-positive cases or RSV-positive cases were collected and analyzed.Results Among all the 1335 specimens,124 were confirmed as HRV-positive cases (9.3％),with IVA-positive rate as the highest (25.1％),followed by RSV-positive rate (15.1％).HRV infection occurred sporadically around the year,with the highest HRV-positive rate seen in spring 2009 and autumn in 2010.Symptoms,signs,chest X-ray,leukocyte count and CRP count did not differ between patients with co-infection or single HRV infection.Clinical symptoms or signs were similar between those with single HRV infection or single RSV infection in children,but the single RSV infected children were more frequently seen with wheeze and cough.28.4％ of the single RSV infected children had bronchiolitis while 10.7％ of single HRV infected children were seen (x2=0.281,P=0.596).Conclusion HRV was a relatively common cause for acute respiratory infections in the eastern areas of Guangdong province.The highest HRV-positive rate was slightly different in different years.Infants and young children were generally susceptible to rhinovirus infection.Bronchiolitis,wheeze and cough associated with HRV infection happened less than those caused by RSV.