Enhancement of murine IgE antibody detection by IgG removal.

RATIONALE: Although animal models for the study of allergic reactions are desirable, the use of mice has been hindered by the lack of sufficiently sensitive in vitro immunoglobulin epsilon (IgE) antibody assays. The aim of this study was to enhance IgE antibody measurements by immunoglobulin gamma (IgG) depletion. METHODS: Seven- to eight-week-old female mice of four strains (C3H/HeJ, CBA/J, C57Bl/6J, and Balb/c) were immunized (20 mice/group) with shrimp or peanut extracts using Al(OH)(3) as adjuvant. Following immunization, animals were sacrificed by exsanguination and the sera of each group pooled. Initial measurements of IgE antibody levels by enzyme-linked immunosorbent assay (ELISA) were relatively low; IgG and IgE reactivity patterns by immunoblot were similar. Thus, sera from shrimp or peanut immunized mice were depleted of IgG (absorbed 3-6 times with immobilized protein G) and then tested for IgE antibody to shrimp or peanut allergen. RESULTS: A 3- to 5-fold increase in IgE antibody reactivity as measured by ELISA was demonstrated when >80-90% of the IgG was removed. This increase in detection of allergen-specific IgE occurred in sera from all mouse strains and to all allergens tested. In addition, reactivity of IgE antibodies to peanut or shrimp allergens by immunoblot increased visually approximately 4- to 10-fold. CONCLUSIONS: These studies indicate that allergen-specific IgG antibodies, which may be in more than 100-fold excess to IgE antibodies, interferes with detection of allergen-specific IgE, probably by competitive binding to allergenic epitopes. Substantial depletion of IgG antibodies (>80%) result in a significant increase in the sensitivity of the antibody measurements.

Evaluating the acquisition of colposcopy skills in an obstetric-gynecologic residency program.

Instruction in colposcopic technique is now an integral component of residency training in obstetrics and gynecology. No statistical method for assessing colposcopy skills has been reported on before. The statistical calculations of sensitivity, specificity and kappa were applied to determine if there was any progressive acquisition of colposcopy skills by the colposcopy trainee during the four-year residency program.

Doubling times of human chorionic gonadotropin increase in early viable intrauterine pregnancies.

Although the doubling time of serum human chorionic gonadotropin has been assumed to be constant in early viable intrauterine pregnancy (prior to 6 to 7 weeks after menses), the range has varied between 1.4 and 3.5 days in the literature. To evaluate this variability of the doubling time, the mean doubling times at different ranges of human chorionic gonadotropin concentrations were determined in 49 normal pregnancies, and the doubling times at different intervals of gestation from both the day of the basal body temperature shift and the last menstrual period. The data obtained from the three different methods indicate that the doubling time of human chorionic gonadotropin is not constant but rather increases with increasing human chorionic gonadotropin concentration or gestational age. In addition, statistical analysis of the semilogarithmic plots of serum human chorionic gonadotropin concentrations indicated that the exponential rate of increase of serum human chorionic gonadotropin significantly decreases with gestational age. Since serum human chorionic gonadotropin doubling times increase and the exponential rate decreases with gestational age, estimates of normal values should be established for small sampling ranges and/or short intervals of gestation.

Use of colposcopically directed, four-quadrant cervical biopsy by the colposcopy trainee.

Colposcopically directed cervical biopsies performed by experienced colposcopists have greatly reduced the need for conization of the cervix to evaluate patients with cervical intraepithelial neoplasia (CIN). Because of the subjectivity of the colposcopic technique and variable time required to become skilled, continued reliance on cervical conization is often recommended to validate colposcopic findings for novice colposcopists . We assessed the colposcopic skill of residents in training in obstetrics and gynecology who had received 9-12 months of instruction in colposcopic techniques. Biopsies of each quadrant of the ectocervix were done after the resident recorded his or her colposcopic diagnosis. In 26% of the patients there was overestimation or underestimation of the histologic findings by more than one grade in the cervical quadrant suspected on colposcopy to contain the most advanced CIN lesion. In 30% of patients the histologically most advanced CIN lesion was not identified by the colposcopist . In 11% of patients with histologic findings of CIN both cytology and colposcopy were negative. Only 69% of the histologically confirmed lesions were diagnosed colposcopically by the resident colposcopists . The four-quadrant, colposcopically directed biospy technique is recommended as an effective training method for the beginning colposcopist .

Fetal sex-related differences in maternal serum alpha-fetoprotein during the second trimester of pregnancy.

In an analysis of data gathered from routine maternal serum alpha-fetoprotein screening, we determined that the sex of the fetus is significantly correlated with differences in maternal serum alpha-fetoprotein concentration during the second trimester of pregnancy. Between the fifteenth and nineteenth gestational weeks, the mean maternal serum alpha-fetoprotein level is significantly higher for the male fetus than for the female fetus. There was no difference, however, in the rate of increase in maternal serum alpha-fetoprotein concentration with time between male and female fetuses during the weeks of gestation that were studied. No apparent cause for these observations has been demonstrated.