Development of a molecular-beacon assay to detect the G1896A precore mutation in hepatitis B virus-infected individuals

The 1896 precore (PC) mutation is the most frequent cause of hepatitis B virus e-antigen (HBeAg)-negative chronic hepatitis B virus (HBV) infection. Detection of the 1896 PC mutation has application in studies monitoring antiviral therapy and the natural history of the disease. Identification of this mutation is usually performed by direct sequencing, which is both costly and laborious. The aim of this study was to develop a rapid, high-throughput assay to detect the 1896 PC mutation using real-time PCR and molecular-beacon technology. The assay was initially standardized on oligonucleotide targets and plasmids containing the wild-type (WT) and PC mutation and then tested on plasma samples from children with HBV DNA of >10(6) copies/ml. Nine individuals were HBeAg negative and suspected to harbor HBeAg mutations, while 12 children were HBeAg positive and selected as controls. Ninety percent (19 of 21) of plasma samples tested with molecular beacons were in complete agreement with sequencing results. The remaining 10% (2 of 21) of samples were identified as heterogeneous mixtures of WT and mutant virus by molecular beacons, though sequencing found only a homogeneous mutant in both cases. Overall, the 1896 PC mutation was detected by this assay in 55.5% of the children with HBeAg-negative infection. In summary, this assay is a rapid, sensitive, and specific technique that effectively discriminates WT from 1896 PC mutant HBV and may be useful in clinical and epidemiological studies.     

Immunogenicity and protective efficacy of the alpha C protein of group B streptococci are inversely related to the number of repeats.

Infection by group B streptococci (GBS) is an important cause of bacterial disease in neonates. Alpha C protein is a protective cell surface-associated protein of GBS. This protein contains a repeat region flanked by N and C termini. Variable expression of tandem repeating units of alpha C proteins had been found among clinical isolates of GBS. We examined the effect of the number of repeats on the immunogenicity of the alpha C protein and its ability to elicit protection from GBS infection in a neonatal mouse model. Mice were immunized with purified alpha C proteins of constructs containing various numbers of repeats (n = 1, 2, 9, and 16) and the N- and C-terminal regions. Both the N-terminal and the repeat regions contain protective and opsonic epitopes. Antibody responses to the alpha C protein constructs with various numbers of repeats were tested with enzyme-linked immunosorbent assay plates coated with either native, nine-repeat alpha C protein or "repeatless" N-terminal antigen. An inverse relationship was found between the number of repeats and the immunogenicity of the alpha C protein; this effect was most pronounced on titers of antibody to the N-terminal region. An inverse relationship was also observed between the number of repeats and protective efficacy, i.e., mouse dams immunized with 5 microg of one- or nine-repeat alpha C protein transferred protective immunity to 65 or 11% of their pups, respectively (P < 0.0001). Thus, the presence of multiple repeats appears to lessen the antibody response to the complete alpha C protein, and especially the antibody response to its N-terminal region, and suggests a mechanism whereby repeat elements contribute to the evasion of host immunity.     

Effects of anonymity,gender, and erotophilia on the quality of data obtained from self-reports of socially sensitive behaviors

This study examined the effects of anonymity, gender, and erotophilia on the quality of self-reports of socially sensitive health-related behaviors. A sample of 155 male and 203 female undergraduate students was randomly assigned to an anonymous and a confidential (i.e., nonanonymous) assessment condition. Gender, erotophilia, self-reports (of substance use, sexual behaviors, illegal activity), and perceived item threat were assessed by questionnaire. Data quality was strongly affected by experimental condition and gender. Thus, terminations were more frequent in the confidential condition and among women. In the confidential condition, women were significantly more likely to prefer not to respond to sensitive items compared to men. Both female gender and confidential condition were associated with lower frequency reports of sensitive health behaviors, and greater perceived threat of the assessment questions. Self-reported engagement in sensitive behaviors was positively related to both perceived question threat and erotophilia. Path analyses suggest that question threat mediates the effects of anonymity manipulations and gender on data quality (item refusal, termination), and that erotophilia mediates the effects of gender on incidence and frequency self-reports. The results indicate that anonymous assessments as well as male gender are associated with better data quality.     

The haemotoxicity of mitomycin in a repeat dose study in the female CD-1 mouse

Mitomycin (MMC), like many antineoplastic drugs, induces a predictable, dose-related, bone marrow depression in man and laboratory animals; this change is generally reversible. However, there is evidence that MMC may also cause a late-stage or residual bone marrow injury. The present study in female CD-1 mice investigated the haematological and bone marrow changes induced by MMC in a repeat dose study lasting 50 days. Control and MMC-treated mice were dosed intraperitoneally on eight occasions over 18 days with vehicle, or MMC at 2.5 mg/kg, autopsied (n = 6-12) at 1, 7, 14, 28, 42 and 50 days after the final dose and haematological changes investigated. Femoral nucleated bone marrow cell counts and levels of apoptosis were also evaluated and clonogenic assays carried out; serum levels of FLT3 ligand (FL) were assessed. At day 1 post-dosing, MMC induced significant reductions in RBC, Hb and haematocrit (HCT) values, and there were decreases in reticulocyte, platelet, and femoral nucleated cell counts (FNCC); neutrophil, lymphocyte and monocyte values were also significantly reduced. On days 7 and 14 post-dosing, all haematological parameters showed evidence of a return towards normal values, but at these times, and at day 28, values for RBC and FNCC remained significantly reduced in comparison with controls. At days 42 and 50 post-dosing, many haematological parameters in MMC-treated mice had returned to control levels; however, there remained evidence of late-stage effects on RBC, Hb and HCT values, and FNCC also continued to be significantly decreased. Results for granulocyte-macrophage colony-forming units and erythroid colonies showed a profound decrease immediately post-dosing, but a return to normal values was evident at day 50. Serum FL concentrations demonstrated very significant increases in the immediate post-dosing period, but a return to normal was seen at day 50 post-dosing; a relatively similar pattern was seen in the number of apoptotic femoral marrow nucleated cells. The histopathological examination of kidney tissues from MMC animals at day 42 and 50 post-dosing showed evidence of hydronephrosis with cortical glomerular/tubular atrophy and degeneration. It is therefore concluded that MMC administered on eight occasions over 18 days to female CD-1 mice at 2.5 mg/kg induced profound changes in haematological and bone marrow parameters in the immediate post-dosing period with a return to normal levels at day 50 post-dosing; however, there was evidence of mild but significant late-stage/residual effects on RBC and FNCC, and on cells of the erythroid lineage in the bone marrow.     

Delineation of the male phenotype in carniofrontonasal syndrome

We are reporting on a 4-generation family in which 6 individuals had frontonasal dysplasia with variable extracranial abnormalities. All affected persons had hypertelorism, bifid or broad nose, and highly arched palate. Associated abnormalities included cleft lip and palate (1/6), webbed neck (2/6), Sprengel anomaly (2/6), pseudoarthrosis of the clavicle (2/6), pectus excavatum (3/6), narrow, sloping shoulders (3/6), diaphragmatic hernia (2/6), broad first toe (4/6), brachydactyly (3/6), fifth finger clinodactyly (5/6), longitudinal grooves of nails (5/6), shawl scrotum (2/3 males), first degree hypospadias (1/3), and mild mental retardation (1/6). Only one affected female had brachycephaly and right coronal synostosis. Four other affected relatives had varying degrees of facial asymmetry, but normal skull contour. No male to male transmission is observed, and both daughters of an affected male were affected. Based on the phenotype of the 3 affected females, craniofrontonasal syndrome (CFNS) is the likely diagnosis. However, there are 3 affected males in this kindred, and 2 of the 3 had significant anomalies. Affected males also had genital abnormalities and pectus deformity of the chest, not previously reported in this condition. Two of the 3 males have posterolateral diaphragmatic hernia. This family expands the phenotype of affected males.     

Clinical comparison of the Isolator 1.5 microbial tube and the BACTEC radiometric system for detection of bacteremia in children.

The Isolator 1.5 microbial tube (E. I. du Pont de Nemours & Co., Inc., Wilmington , Del.) was compared with the BACTEC radiometric detection system (Johnston Laboratories, Inc., Cockeysville, Md.) for the detection of bacteremia in children. The Isolator 1.5 is a blood culture system designed for small volumes of blood (0.5 to 1.5 ml). The method involves lysis of the cells of the patient and the direct plating of the entire blood lysate on agar media appropriate for the growth of fastidious microorganisms. Of 1,500 paired samples inoculated into the two systems, 68 were positive for 73 clinically significant organisms. The Isolator 1.5 recovered 81% of the positive cultures compared with 84% recovered by the BACTEC system. When paired blood samples with disproportionate volumes were excluded, the Isolator 1.5 detected 3% more positive cultures. More isolates of Streptococcus pneumoniae and Neisseria meningitidis were recovered by the Isolator 1.5, whereas Haemophilus influenzae was recovered most often in the BACTEC bottles (P greater than 0.1). The contamination rates were 8.7 and 3.1% for the Isolator 1.5 and the BACTEC system, respectively. In cultures positive by both systems, the mean time to detection was 4.1 h faster with the Isolator 1.5. The mean time to obtain isolated colonies was 26.6 h faster with the Isolator 1.5. These data indicate the potential value of the Isolator 1.5 microbial tube as a simple, rapid, and sensitive method for the detection of bacteremia in children.     

Nutritionally variant Streptococcus pyogenes from a periorbital abscess.

A nutritionally variant Streptococcus pyogenes strain was isolated from a periorbital abscess. The organism was identified with the use of three rapid biochemical test kits, and the group A antigen was detected by conventional serology as well as direct antigen detection tests.     

Reliability of CD4 quantitation in human immunodeficiency virus-positive children: implications for definition of immunologic response to highly active antiretroviral therapy

Our objective was to develop data-based algorithms for definition of immunologic response to AIDS therapies in pediatric patients, taking account of T-cell subset measurement errors. The study design involved cross-protocol analysis of 2,148 enrollees in six completed Pediatric AIDS Clinical Trials Group trials. We used standard quantitation of T-cell subsets; linear modeling with mean-dependent measurement error variance was used to develop 95% tolerance limits for change in CD4%. For individuals with a CD4% of approximately 25%, the measurement error-based 95% tolerance interval ranges from 15% to 35%, whereas for individuals with a CD4% of approximately 5%, the tolerance interval ranges from 3% to 7%. When pairs of CD4% measures taken within a time interval of less than 30 days are averaged to estimate steady-state CD4%, tolerance interval width decreases by approximately 30%. A simple graphical tool that provides a data-based criterion for immunologic response over and above variation ascribable to T-cell measurement error is provided. Variability in CD4% due to measurement error is substantial, increases with level of CD4%, and complicates assessment of immunologic response to therapy. Replicates of CD4% measures could be used to improve precision of interpretation of CD4% measures.