Binding kinetics of monoclonal antibody using antigen-beta-galactosidase hybrid protein: application to measurement of peptide antigenicity

A simple method for determination of binding kinetics of a solid-phase antibody using antigen-beta-galactosidase hybrid protein was evaluated. To minimize conformational change of the antigen binding site of the antibody when directly binding to a microtiter plate, the microtiter plate was precoated with protein A. The binding and free antigen concentrations were directly obtained from the beta-galactosidase activity. This method can be used for analyses of the equilibrium dissociation constant (KD), and the association (Kass) and dissociation (Kdiss) rate constants. Peptide antigenicity was also analyzed by competitive ELISA using this method. Since both antigen-beta-galactosidase and the peptide used are localized in the fluid-phase, the proper affinity constant (KA) of the peptide can be estimated from the KD value of the antigen-beta-galactosidase-antibody interaction, and from the IC50 value of the peptide.     

Prediction of residual retroperitoneal mass histology after chemotherapy for metastatic nonseminomatous germ cell tumor: multivariate analysis of individual patient data from six study groups

PURPOSE: To develop a statistical model that predicts the histology (necrosis, mature teratoma, or cancer) after chemotherapy for metastatic nonseminomatous germ cell tumor (NSGCT). PATIENTS AND METHODS: An international data set was collected comprising individual patient data from six study groups. Logistic regression analysis was used to estimate the probability of necrosis and the ratio of cancer and mature teratoma. RESULTS: Of 556 patients, 250 (45%) had necrosis at resection, 236 (42%) had mature teratoma, and 70 (13%) had cancer. Predictors of necrosis were the absence of teratoma elements in the primary tumor, prechemotherapy normal alfa-fetoprotein (AFP), normal human chorionic gonadotropin (HCG), and elevated lactate dehydrogenase (LDH) levels, a small prechemotherapy or postchemotherapy mass, and a large shrinkage of the mass during chemotherapy. Multivariate combination of predictors yielded reliable models (goodness-of-fit tests, P > .20), which discriminated necrosis well from other histologies (area under the receiver operating characteristic (ROC) curve, .84), but which discriminated cancer only reasonably from mature teratoma (area, .66). Internal and external validation confirmed these findings. CONCLUSION: The validated models estimate with high accuracy the histology at resection, especially necrosis, based on well-known and readily available predictors. The predicted probabilities may help to choose between immediate resection of a residual mass or follow-up, taking into account the expected benefits and risks of resection, feasibility of frequent follow-up, the financial costs, and the patient's individual preferences.     

Hereditary exostoses--presentation of a family case

In this article we present a Norwegian family with hereditary multiple exostoses and a review of relevant literature. 21 family members were examined; ten males and six females had multiple exostoses, the youngest from six months of age. The exostoses had led to compression of nerves, disturbance of bone growth with shortening and bowing of the forearm bones, and valgus deformity of the knee and ankle. Physical function and quality of life was generally well preserved. Contrary to most reports, nearly half of the patients had allegedly noticed growth or debut of exostoses in adulthood. Almost half of the patients had had the exostoses removed surgically twice, (median value). Malignant transformation of exostoses has not been observed in the family.     

Multicenter study of case finding in elderly emergency department patients

OBJECTIVES: To assess the feasibility of a brief comprehensive case-finding program for detecting functional, cognitive, and social impairments among elderly ED patients and to estimate the prevalence of unknown, undetected, or untreated impairments elderly patients may have. METHODS: A multicenter prospective study conducted at five private and public hospital EDs in five different communities across the country. Patients aged 60 years and older released to their homes during 52 randomly selected evening and weekend shifts between February 1 and April 30, 1993, were eligible for the case-finding program. They were evaluated by medical students who received special training (instructional videotape, supervised examinations, and conference calls) in the administration of a standardized 17-item protocol that included an interview and simple tests of function. The patients' physicians were notified of the screening results and were asked to return a one-month follow-up questionnaire. The physicians answered whether the presumed problem had been confirmed and whether a treatment plan for a new problem had been developed. RESULTS: Patient acceptance of the case-finding program was good; 252 of 338 eligible patients (75%) agreed to participate, and 281 conditions were detected for 242 screened patients (96%). The most frequently reported problems were with: performing the activities of daily living (79%); vision (55%); lack of influenza vaccination (54%); home environment (49%); mental status (46%); general health (41%); falls (40%); and depression (36%). The physicians returned questionnaires for 153 patients (63%); 76 patients (50%) were evaluated at follow-up visits, during which 47 newly identified problems (62%) were confirmed and treatment plans were developed for 25 problems (53%) among 21 patients. A mean time of 17.7 +/- 10.2 minutes was required to complete the screen. CONCLUSIONS: A brief comprehensive case-finding program for functional, cognitive, and social impairment among elderly ED patients is feasible. The screening uncovered a significant amount of morbidity among older patients visiting EDs.     

Biochemical mediators of meningeal inflammatory response to group B streptococcus in the newborn piglet model

The meningeal inflammatory response to a heat-killed mutant unencapsulated strain of type III group B Streptococcus (GBS) was studied in a newborn piglet model. GBS (10(9) colony-forming unit equivalents) or saline (control) was inoculated intraventricularly. Serial cerebrospinal fluid measurements were done at baseline and over the course of the next 24 h for cytochemical changes and production of tumor necrosis factor (TNF) and prostaglandins. In separate experiments, we defined the time course of early changes during the first 6 h and dose response relationship over a range of inocula 10(6) to 10(9) colony-forming unit equivalents. The intraventricular inoculation of the heat-killed unencapsulated GBS induced marked leukocytosis and increased protein by 6 h. These changes were preceded by a several hundredfold increase in TNF (maximum at 2 h) and prostaglandins (maximum at 2-4 h). The early and sharp rise in TNF suggests its pivotal role in initiating the inflammatory cascade. The magnitude of the inflammatory response increased with increasing bacterial dose over the range studied. To study the effect of encapsulation of GBS in the induction of meningeal inflammation, we compared the response to the unencapsulated mutant strain with that to the encapsulated parent strain. The encapsulated strain produced much smaller inflammatory changes, and only with high doses of bacteria. The GBS cell wall appeared to be the primary bacterial product triggering inflammation. Intraventricular injection of the heat-killed unencapsulated GBS with exposed cell wall can serve as a valid model for studying neonatal meningitis.     

CD23 deficient mice develop allergic airway hyperresponsiveness following sensitization with ovalbumin

The low affinity receptor for IgE (CD23) is reported to regulate immune and inflammatory events and as a result, it may have a role in the development of allergic airway inflammation and hyperresponsiveness (AHR). To test this hypothesis CD23-deficient mice were studied following different modes of allergic sensitization. Mice were actively sensitized either intraperitoneally with ovalbumin (OA)/alum or via the airways (10 days exposure to OA aerosol with no adjuvant). Passive sensitization was performed by intravenous injections of OA-specific IgE. Airway responsiveness, serum IgE and IgG levels were assessed together with airway inflammation. Passive sensitization followed by airway challenges resulted in increased OA-specific lgG and IgE in the serum of wild-type mice only, while both the CD23+/+ and CD23-/- groups developed tracheal smooth muscle hyperresponsiveness to electrical field stimulation, indicating that IgE/CD23-mediated immune functions may not be necessary for the development of allergic changes. Active sensitization of both CD23-/- and CD23+/+ mice resulted in increased serum levels of OA-specific IgE and lgG, airway eosinophilia and significant AHR when compared with nonsensitized mice. The genetic deficiency of CD23-/- mice not only failed to prevent but was associated with a significant increase of these responses. These results indicate that CD23 may not be essential for the development of allergen-induced AHR and further, that its presence may have some inhibitory effects on the allergic response.     

Dual specificity and the formation of stable autoimmune complexes

Since dual specificity at the antibody active-site level involves new principles relative to monospecific antigen-antibody interactions and may be a general property of autoantibodies, it was important to further characterize such antibodies. Four lupus derived autoantibodies were studied to understand parameters and mechanisms involved in the participation of dual-specific antibody molecules in the formation of highly stable immune complexes. Because the dual-specific binding properties of selected lupus-related murine autoantibodies had been previously described using a solid-phase polystyrene-based ELISA, a conformational sensitive membrane based assay (CSI) was used on a comparative basis to further characterize NZB/NZW F1 murine monoclonal anti-DNA autoantibodies BV 04-01 (anti-ssDNA), BV 16-19 (anti-ssDNA), BV 17-45 (anti-dsDNA), and BV 16-13 (anti-dsDNA). All four monoclonal autoantibodies exhibited anti-IgG binding in the solid-phase ELISA. However in the CSI assay, only anti-dsDNA monoclonal autoantibodies BV 17-45 and BV 16-13 demonstrated anti-IgG binding, while anti-ssDNA autoantibodies BV 04-01 and BV 16-19 did not. Upon subjection to time-dependent thermal denaturation, with and without thiol reduction at 100 degrees C in the CSI, the self-binding activities of BV 17-45 and BV 16-13 were abrogated demonstrating that the recognized IgG autoepitope(s) possessed conformational or discontinuous three-dimensional properties. The immunological implications of dual specificity are discussed on a structure-function basis and its correlation with formation of pathogenic immune complexes.     

Comparison of single-dose oral grepafloxacin with cefixime for treatment of uncomplicated gonorrhea in men. The STD Study Group

In a randomized open study, 351 male patients with uncomplicated gonorrhea were given single oral doses of grepafloxacin (400 mg) or cefixime (400 mg). In the 299 microbiologically evaluable patients, urethral infections were cured in 99% (147 of 149) of those receiving grepafloxacin and 97% (145 of 150) of those given cefixime. Eradication rates for both regimens were 100% in the 16% (47 of 299) of participants who were infected with penicillin-resistant Neisseria gonorrhoeae and 97% in the 21% (62 of 299) of participants infected with tetracycline-resistant strains. Grepafloxacin is a well-tolerated alternative to cefixime for treatment of uncomplicated gonorrhea in males.