CROSS-OVER TRIALS WITH CENSORED DATA

Cross-over trials assign two or more treatments sequentially to the same subject; groups of subjects receive different treatment sequences. Both parametric and non-parametric methods of inference are available for cross-over trials with complete data. In this paper we develop methods for estimation and testing in cross-over trials with censored data, based partly on methods used for complete data. Our estimator is consistent for the true effects. Simulation results show that both of our proposed tests have approximately nominal size. We compare our procedures to a method for cross-over designs based on Cox regression proposed by France, Lewis and Kay. We demonstrate that our method of estimation is superior to the Cox-based method, which has considerable bias. Both of the tests presented here have more power than the Cox-based tests in all of the situations we investigated. The estimation and test procedures apply to other designs, such as parallel trials and repeated measures designs.     

Influential Factors of Caregiver Behavior at Mealtime: A Study of 24 Child-Care Programs

Objective To measure the nutrition knowledge and attitudes of caregivers in child-care programs and to observe the behaviors of caregivers as they interact with children at mealtime.Design A nonexperimental research design. Nutrition knowledge and attitudes toward nutrition were measured using survey methodology designed for this study. Observers measured caregiver behavior by means of observation and quantified it using a behavior checklist. Interrater reliability was 98%. Instruments were piloted and content validity was established. Using Cronbach's α, reliability was 0.69 and 0.67, respectively.Subjects/setting Participants were 113 caregivers in 24 licensed child-care programs in three counties in Illinois.Statistical analyses performed The independent variables (caregiver nutrition knowledge, caregiver nutrition attitudes, years of teaching, prior nutrition training, and education level) were correlated to the dependent variable (caregiver behavior), using the Pearson product moment correlation. The combination of variance from all independent variables was analyzed using the general linear regression model.Results Although caregivers held beliefs that should have a positive influence on children's eating behaviors, they demonstrated low knowledge of nutrition and displayed behaviors at mealtimes that were inconsistent with their beliefs and expert recommendations. Positive correlations were found between nutrition knowledge and behavior at mealtime, nutrition knowledge and attitudes, and attitudes and caregiver behavior.Applications These instruments can be used to assess and teach nutrition practices through self-assessment, training, and coursework. Results also begin to define the role of the caregiver in children's nutrition practices. Results demonstrate that caregiver behavior can be enhanced by addressing nutrition knowledge and attitudes.     

Invasive nasal sarcoidosis treated with methotrexate

A patient with invasive sarcoidosis is described in whom upper respiratory tract symptoms were the presenting complaint of this severely disfiguring disease. Methotrexate was used as an effective alternative to high dose systemic steroids which were contraindicated in this case.     

Epidermolysis bullosa acquisita associated with chronic lymphatic leukaemia

A 61–year-old man developed epidermolysis bullosa acquisita (EBA) in association with an IgM paraprotein and chronic lymphatic leukaemia (CLL). Direct immunocyto-chemistry and immunoelectron microscopy confirmed the presence of IgM at the dermoepidermal junction. IgG was not present. This appears to be a unique observation in EBA and is discussed in relationship to the possible pathogenesis of the disorder.     

PREFERRED CONFORMATION OF THE tert-BUTOXYCARBONYLAMINO GROUP IN PEPTIDES

Structural parameters, derived from X-ray crystallographic data, have been compiled for amino acid and linear peptide derivatives which contain the N-terminal tert-butoxycarbonyl (Boc) group or its next higher homolog, the tert-amyloxycarbonyl group. The comparison of the geometry of the urethane group in Boc-derivatives with that of the peptide group shows small differences in bond angles about the trigonal carbon, because of altered interactions when a CαH group of a peptide unit is replaced by an ester oxygen. In contrast to the strong preference of the peptide bond for the trans form (except when it precedes proline), the urethane amide bond adopts both the cis and trans conformations in crystals. The cis urethane conformation is preferred in crystals of compounds with a tertiary nitrogen (such as Boc-Pro) or in structures stabilized by strong intermolecular interactions. Conformational energy computations on Boc-amino acid N'-methylamides indicate that the trans and cis conformations of the urethane amide bond have nearly equal energies (even for amino acids other than proline), in contrast to the peptide bond, for which the trans conformation has a much lower energy. The computed increase of the cis content in Boc-amino acid derivatives (as compared with the corresponding N-acetyl derivatives) is consistent with the observed distributions of conformations in crystal structures and with n.m.r. studies in solution. Usually, the substitution of a Boc for an N-acetyl end group does not alter the conformational preferences (as indicated by φ, Ψ values and relative energies) of the amino acid residue which follows the end group when the amide bond is trans. Particular conformations, however, can be stabilized by strong attractive interactions between some side chains (e.g. that of phenylalanine) and the bulky Boc end group.     

Detection of antibodies in sera from Chagas' disease patients using a Trypanosoma cruzi immunodominant recombinant antigen

A Trypanosoma cruzi DNA fragment encoding an immunodominant repetitive antigen (H49) was subcloned into a protein purification and expressed system. Purified H49 peptide reacted specifically in an enzyme-linked immunosorbent assay (ELISA) with sera from T. cruzi-infected patients, but not with sera from patients with other parasitic diseases such as leishmaniasis and T. rangeli-infection. The H49 recombinant ELISA was able to detect specific antibodies in 84% of chronic chagasic serum samples tested. One of the major advantage of the recombinant ELISA for serodiagnosis of chronic Chagas’disease resides in its high specificity (100%). Our data suggest that recombinant peptides could provide a practical basis for specific diagnosis tests for Chagas’disease.