ABSTRACT
Co-circulating variants of influenza A/H3N2 viruses in children were studied in Houston, Texas between October 1997 and March 1998 to assess the effects of a new variant strain on the severity of clinical illness. Influenza A virus was isolated from the nasal wash or nasal aspirate specimens collected from children at two tertiary care hospitals, and 271 isolates were available for variant-specific subtyping using RT-PCR and restriction fragment length polymorphism (RFLP) analysis. We classified 124 (46%) influenza viruses as A/H3N2/Wuhan/359/95-like and 137 (50%) as A/H3N2/Sydney/05/97-like. Ten (4%) virus isolates could not be classified. Ill contacts in the household were reported more frequently in patients infected with A/Sydney-like viruses than in those infected with A/Wuhan-like viruses (85% vs. 71%, respectively, P=0.02). There were no differences in other demographic variables among children infected with these strains. This study found no increase in illness severity in children infected with a newly emerging strain.
Subject(s)
Communicable Diseases, Emerging/epidemiology , Influenza A Virus, H3N2 Subtype , Influenza A virus/classification , Influenza A virus/genetics , Influenza, Human/epidemiology , Child , Child, Preschool , Communicable Diseases, Emerging/prevention & control , Communicable Diseases, Emerging/virology , Comorbidity , Female , Humans , Infant , Infant, Newborn , Influenza, Human/prevention & control , Influenza, Human/virology , Male , Molecular Epidemiology , Multivariate Analysis , Odds Ratio , Polymorphism, Restriction Fragment Length , Prevalence , Proportional Hazards Models , Reverse Transcriptase Polymerase Chain Reaction , Risk Factors , Texas/epidemiologyABSTRACT
Mutations in N-acetyltransferase 2 (NAT2), a highly polymorphic enzyme involved in the metabolism of xenobiotics and carcinogens, may affect risk for colorectal cancer (CRC), especially among individuals with germ-line mutations in DNA mismatch repair genes. We determined the NAT2 genotypes and allele frequencies for 86 individuals with CRC who had mutations in hMLH1, hMSH2, or hPMS1. No significant difference in time to onset was observed between rapid (NAT2*4) and slow (NAT2*5, NAT2*6, and NAT2*7) acetylators. However, when individuals were stratified separately by NAT2 polymorphism (NAT2*5, NAT2*6, and NAT2*7), those who were heterozygous at the mutant locus NAT2*7 after adjustment for the NAT2 mutant loci NAT2*5 and NAT2*6 had a significantly higher risk of CRC (hazard ratio, 2.96; P = 0.012) and all of the cancers (hazard ratio, 3.37; P = 0.00004) than individuals homozygous for wild type at the NAT2*7 allele. These findings suggest that NAT2 genotype may be an important factor in tumorigenesis of CRC and cancers related to hereditary nonpolyposis CRC among individuals with mismatch repair defects.
Subject(s)
Arylamine N-Acetyltransferase/genetics , Colorectal Neoplasms, Hereditary Nonpolyposis/genetics , Colorectal Neoplasms/genetics , DNA Repair/genetics , DNA-Binding Proteins , Acetylation , Adaptor Proteins, Signal Transducing , Age Factors , Alleles , Arylamine N-Acetyltransferase/metabolism , Base Pair Mismatch/genetics , Carrier Proteins , Female , Genetic Predisposition to Disease/genetics , Germ-Line Mutation , Heterozygote , Humans , Male , Middle Aged , MutL Protein Homolog 1 , MutL Proteins , MutS Homolog 2 Protein , Neoplasm Proteins/genetics , Nuclear Proteins , Phenotype , Polymorphism, Single-Stranded Conformational , Proto-Oncogene Proteins/genetics , Risk FactorsABSTRACT
The performance of a new, rapid, easy-to-perform assay based on neuraminidase enzyme activity for detection of influenza virus types A and B was compared to detection by culture, indirect immunofluorescence, and enzyme immunoassay in 479 nasal wash specimens from children with respiratory infections. Compared to isolation of influenza virus by culture, the neuraminidase assay had a sensitivity of 70.1%, specificity of 92.4%, positive predictive value of 76.3%, and negative predictive value of 89.9%. There was a higher sensitivity for the detection of influenza A virus (76.4%) than for influenza B virus (40.9%). Indirect immunofluorescence showed a sensitivity of 59.8% and specificity of 97% compared to culture isolation for detection of influenza A and B viruses. Enzyme immunoassay showed a sensitivity of 89.7% and specificity of 98.1% for the detection of influenza A alone. The quality of the nasal wash specimen had a significant effect on the detection of influenza virus by all of the assays. A strong response of the neuraminidase assay was more likely to represent a culture-confirmed influenza infection. This new rapid neuraminidase assay was useful for the detection of influenza A and B viruses in nasal wash specimens.
