Rapid assay for von Willebrand factor activity using formalin-fixed platelets and microtitration technic.

An inexpensive assay for von Willebrand factor using microtitration plates, formalin-fixed platelets, and ristocetin is described. With this technic, the assay for von Willebrand factor is simple enough to be considered for use in any diagnostic laboratory for patients with prolonged bleeding times.     

Human papillomavirus type 6 detected by the polymerase chain reaction in invasive sinonasal papillary squamous cell carcinoma.

Eight sinonasal carcinomas (one adenocarcinoma, two undifferentiated nasopharyngeal carcinomas, and five squamous cell carcinomas) were investigated for evidence of human papillomavirus (HPV) infection using in situ hybridization and the polymerase chain reaction for HPV types 6, 11, 16, 18, and 33. All eight cases were negative for HPV infection by in situ hybridization, while a single HPV-6-positive case was identified by the polymerase chain reaction. The HPV-positive case was an invasive papillary squamous cell carcinoma of the maxillary sinus. Although HPV-6 is usually associated with benign anogenital condylomata, it has been identified in malignant lesions of the upper respiratory tract. This may reflect exposure of the upper aerodigestive tract to additional carcinogens, such as smoke and alcohol, superimposed on the background proliferative stimulus of the HPV infection.     

Predictors and Sequelae of Smoking Topography Over the Course of a Single Cigarette in Adolescent Light Smokers

PurposeThe objective of this study was to determine whether adolescent smokers, who varied in their smoking histories and symptoms of nicotine dependence, exhibit any decrease in puff volume and duration similar to that typically seen in dependent adolescent and adult smokers. Moreover, we examined whether puffing trajectories were moderated by individual difference factors, as well as whether puffing topography over the course of smoking a single cigarette was predictive of an escalation in dependence symptoms.MethodsWe assessed smoking topography (puff number, duration, volume, maximum flow rate [velocity], and inter-puff interval) over the course of smoking a single cigarette in a sample of 78 adolescent light smokers, using hierarchical linear modeling. We examined moderators (anxiety, depression, nicotine dependence) of the topographic trajectories, as well as whether smoking topography predicted any change in dependence over a 2-year period.ResultsPuff volume and puff duration decreased over the course of smoking the cigarette, whereas puff velocity and inter-puff interval increased. Slopes for puff volume and duration were moderated by anxiety and depressive symptoms. Moreover, individuals with a less “typical” topography pattern (exhibited stable or increasing volume and duration over the course of smoking the cigarette) demonstrated a heightened dependence escalation in the subsequent 2 years.ConclusionOur findings suggest that adolescent light smokers self-regulate nicotine during the course of smoking a single cigarette, similar to that reported in dependent adolescent and adult smokers. However, single cigarette self-regulation was influenced by certain affective factors. Implications of these findings and future directions for adolescent smoking research are discussed.     

Factor V Leiden and factor V R2 allele: high-throughput analysis and association with venous thromboembolism

Thrombophilia is a multigenic disease in which the combination of genetic polymorphisms increases the risk of deep vein thrombosis (DVT). The rapid identification of these genetic combinations requires high-throughput analysis of single nucleotide polymorphisms (SNPs). The TaqMan fluorogenic 5'-->*3' nuclease assay (PE/Applied Biosystems, Foster City, CA) with custom-designed primers, probes and controls has provided a highly efficient platform for high throughput. This assay was used to rapidly detect two SNPs, FV Leiden (G1691A) and FV A4070G (R2 allele), in a study of 6295 subjects. With one thermal cycler, we completed sample set-up, PCR and analysis on 84 samples in 3 h with an additional 12 wells containing 4 "no template controls" (NTC), 4 "allele-1 controls", and 4 "allele-2 controls" in a 96-well plate. When additional thermal cyclers were used and more assays were set up while the initial sets of reactions were in the PCR machines, the output could correspondingly be increased. The TaqMan assay was extremely accurate, avoided contamination by using uracil-N-glycolase (UNG) in a single, closed tube, and offered the possibility for additional automation with robotic equipment to implement the PCR. This TaqMan assay facilitates high throughput to screen large populations quickly and economically while utilizing a simple protocol that requires minimal expenditure of personnel time. Our results demonstrated a prevalence of the R2 allele of 11.9% in U.S. Caucasians, 5.6% in African-Americans, 13.4% in Asian or Pacific Islanders and 11.3% in Hispanics. No association between venous thromboembolism and the R2 allele was noted, and furthermore no interaction with FV Leiden was observed.     

Age and human immunodeficiency virus infection in persons with hemophilia in California.

Thirteen hemophilia centers provide comprehensive care to approximately 90 percent of persons with hemophilia in California. For 1987, these centers reported patient human immunodeficiency virus (HIV) antibody status, age group, level of clotting factor deficiency, and hemophilia type on 1,438 persons with hemophilia A and B; HIV serologic status was known for 860 persons (59.8 percent) of whom 537 (62.4 percent) were HIV-antibody-positive. The HIV positivity rate increased with age after taking into account hemophilia type, clotting factor level and treatment center type. The three-year cumulative incidence of reported AIDS (acquired immunodeficiency syndrome) cases based on the number of HIV positive patients, was 11.6 percent. The cumulative incidence rate was 14.6 percent (54 of 370) for those patients over 20 years of age and 4.8 percent (8 of 167) for those under 21 years of age. Although a comparable distribution of the date of diagnoses of AIDS was seen by age group, there appeared to be a bimodal distribution in the rate of AIDS among the age groups, with the 6-12-year-olds and the 21 and older age groups showing higher incidence rates.     

Response to measles, mumps, and rubella revaccination among HIV-positive and HIV-negative children and adolescents with hemophilia. Hemophilia Growth and Development Study.

The effect of human immunodeficiency virus (HIV) infection on response to measles, mumps, and rubella revaccination in children and adolescents with hemophilia was evaluated. Antibody levels of measles, mumps, and rubella were assayed at baseline and two annual examinations in 207 HIV-positive and 126 HIV-negative hemophiliacs participating in the Hemophilia Growth and Development Study (HGDS). Response to revaccination was analyzed for participants whose antibody levels were below the cut-off at the start of a year-long observation period. Among HIV-positive participants, antibody levels were below cut-off in 52 subjects for measles, in 71 for mumps, and in 96 for rubella. Among HIV-negative participants, antibody levels were low in 23 subjects for measles, in 23 for mumps, and in 31 for rubella. For measles and mumps antigens, revaccination was associated with a significant increase in redraw antibody levels for HIV-negative participants. Although there was an increase in the mean measles titers for revaccinated HIV-positive participants, it was not significant. Revaccination was associated with an increase in rubella antibodies in HIV-positive and HIV-negative participants. Revaccination with measles and mumps was associated with an increase in antibody levels in HIV-negative participants but not in HIV-positive participants. Both HIV-positive and HIV-negative participants responded to rubella revaccination with an increase in antibody levels.