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Stocks of the WHO islet cell antibody, GAD65 antibody, and IA-2 antibody standard (NIBSC 97/550) are now very limited. We have therefore made and tested a series of control preparations in which human monoclonal autoantibodies to IA-2 and to GAD65 were diluted in antibody-negative human serum to different concentrations. Three different diabetes autoantibody controls (DAC 1–3) were made as was a negative control preparation. Aliquots containing 1 mL of autoantibodies in serum were freeze-dried. After reconstitution (with 1 mL of water) the controls were tested by 125I-IA-2 immunoprecipitation assay (IPA), 125I-GAD65 IPA, GAD65 Ab ELISA and IA-2 Ab ELISA (kits from RSR Ltd.) and for ICA by immunofluorescence test (IFT). DAC1 is particularly suitable as a control for the 125I IA-2 IPA; DAC2 is suitable for the 125I-GAD65 IPA, GAD65 Ab ELISA, and IA-2 Ab ELISA; and DAC3 is suitable for the ICA IFT. Freeze-dried preparations showed good stability at 37°C. Reconstituted liquid preparations were stable when stored at 4°C and at 37°C. Availability of an essentially unlimited supply of these reagents should be useful in establishing reproducible and comparable measurements of diabetes autoantibodies in different laboratories using different assays. [ABSTRACT FROM AUTHOR]

This study evaluated whether the African cyprinidBarbus neumayerifrom Rwembaita Swamp(low-oxygen) and Njuguta River(high-oxygen) in the Kibale National Park, Uganda differed in traits related to aerobic and anaerobic metabolic potential. Haematocrit was measured as an index of blood oxygen-carrying capacity, and tissue activities and isozyme composition of lactate dehydrogenase(LDH) were measured as indices of tissue anaerobic capacity. To address whether site-dependent differences were acute responsesv. longer-term adjustments to environmental conditions, these variables were measured in fish sampled shortly after collection and after laboratory maintenance under well-aerated conditions. In fish sampled in the field, those from the low-oxygen site had significantly higher haematocrit, but this difference disappeared after long-term laboratory maintenance. In contrast, fish from the low-oxygen site had higher liver LDH activities than fish from the high-oxygen site, and this difference persisted during laboratory maintenance. Polymorphism was detected at both the LDH-A and LDH-B loci, and genotype frequencies for LDH-B differed significantly between collection sites. These results demonstrate physiological, biochemical and genetic differences inB. neumayerifrom habitats differing in dissolved oxygen availability and suggest both acute and long-term responses to local environmental conditions. [ABSTRACT FROM AUTHOR]

Thyroglobulin autoantibodies synthesized by Hashimoto lymphocytes in culture and present in serum have been analysed in terms of their IgG subclass distribution. The autoantibodies produced in vitro were frequently IgG4 or IgGl, whether pokeweed mitogen or Epslein­Barr virus was used to stimulate the cultures, and the subclass distribution of these thyroglobulin antibodies was similar to that observed in the patients' serum. It appears therefore that the antibodies synthesized in vitro in response to polyclonal B-cell activators resemble those produced in vivo, and it seems likely that that pokeweed mitogen and Epstein­Barr virus influence the same B-cell precursors of autoantibody-synthesizing cells, albeit by different mechanisms. [ABSTRACT FROM AUTHOR]

Lymphocytes from thymus, blood, lymph nodes and thyroid tissue of patients with autoimmune thyroid disease have been assessed for their ability to synthesize thyroid autoantibodies spontaneously or following stimulation by Pokeweed mitogen (PWM). Blood and thymic lymphocytes synthesized lgG and microsomal or thyroglobulin antibodies of IgG class in response to PWM (and were therefore probably B-memory cells), while thyroid lymphocytes frequently secreted autoantibodies spontaneously. Lymph node lymphocytes resembled blood lymphocytes in terms of increased production of IgG in response to PWM; however, spontaneous secretion of thyroid autoantibodies was observed in some lymph node suspensions, and the magnitude of the increment in thyroid autoantibodies synthesized in response to PWM was lower than that observed for blood lymphocytes. Fractionation of B-cell enriched populations on density gradients and subsequent incubation of the fractions with T cells and PWM demonstrated that, whereas blood B cells capable of synthesizing autoantibodies were found in both medium and low density fractions, lymph node precursors of thyroid autoantibodies-secreting cells were associated almost exclusively with the light fractions. The presence in lymph nodes of small numbers of low density B cells, compared with a much higher proportion of the heterogeneous population capable of secreting IgG, could account for the discrepancy between the IgG and autoantibodies response to PWM. Further, it seems likely that the density difference in the autoantibodies precursor population of lymph nodes and blood is related to the difference in the state of activation of B cells in these lymphoid organs. [ABSTRACT FROM AUTHOR]

The humoral immune response to tetanus toxoid has been studied in patients with Hashimoto's disease. Although the magnitude of the response was similar to that observed in normal subjects, the Hashimoto patients demonstrated an inability to regulate their levels of tetanus toxoid antibody. This apparent defect in the control of antibody synthesis may be an important factor in both the initiation and perpetuation of autoimmune thyroid disease. [ABSTRACT FROM AUTHOR]

The estimation of the bulk-solvent contribution to the diffraction of a macromolecular crystal makes use of a solvent mask which delimits the bulk-solvent regions in the crystal. It is shown that the way this mask is usually defined in CNS contains a bias which can lead to absurd results in the case of very large structures, where the calculations can only be made on relatively coarse grids. A modified procedure is described and applied to 70S ribosome data at 5.5 A resolution. The B factor affecting the bulk solvent is also discussed. Even in this case of very high and widely variable atomic B factors, it seems sufficient to consider a constant and isotropic B factor for the bulk solvent. This is initially set to the average value of the atomic B factor, but can be refined.