ULTRASTRUCTURAL LOCALIZATION OF CALCITONIN IN THE PARAFOLLICULAR CELLS OF PIG THYROID GLAND WITH CYTOCHROME c-LABELED ANTIBODY FRAGMENTS

Parafollicular cells in mammalian thyroid glands are thought to be responsible for the secretion of calcitonin. In this study, calcitonin was localized in pig thyroid gland by an indirect immunocytochemical technique using rabbit antiserum directed against synthetic porcine calcitonin for the first step, and sheep Fab fragments prepared against rabbit Fab and coupled to cytochrome c for the second step. The antigenic determinants of calcitonin were present only in the parafollicular cells, whose secretory granules were heavily labeled. Labeling of the cytoplasmic matrix is thought to indicate a possible leakage of the polypeptide from the granules. A striking observation was the complete absence of labeling in the cisternae of the rough-surfaced endoplasmic reticulum and of the Golgi apparatus. It is concluded that the secretory granules of parafollicular cells contain calcitonin; the mechanism of synthesis of this peptide is not clearly understood

Ultrastructural localization of intracellular antigen using enzyme-labeled antibody fragments

The efficiency of small enzyme-labeled tracers for the demonstration of intracellular antigen was investigated in tissues fixed with picric acid-formaldehyde. The influence of fixation on the immunological activity was tested in vitro by radial immunodiffusion. The experimental model consisted of newborn pig jejunum after absorption of ferritin from the intestinal lumen. Ferritin was located after 1 hr in vacuoles scattered in the cytoplasm of the absorptive cells and represented an easily recognizable intracellular antigen. After immunohistochemical treatments with antiferritin preparations, the distribution of labeling enzyme reaction product was examined by morphometry. The ratio of the labeled volume to the total volume of vacuoles containing ferritin indicated the degree of specific labeling of the antigen. In both direct and indirect methods, the degree of labeling was low when enzyme-labeled immunoglobulin G was the tracer. With antigen binding fragments (Fab), the labeling was significantly increased. In the indirect method, the degree of labeling was influenced by the first-step reagents. Onlywhen the serum titer was optimum was a high degree of labeling obtained. With antigen binding fragments or papain-digested serum the effect of the titer was negligible and maximum labeling was achieved. In both methods, with peroxidase as the labeling enzyme, a diffuse nonspecific deposition of reaction product was observed. This could be avoided by using cytochrome c instead

Symmetric friction dampers in beam-to-column joints for low-damage steel MRFs

Different types of seismic dampers are available on the market of constructions. The more effective solutions are characterized by (i) stable and predictable response, (ii) localisation of demand into the dampers minimizing the post-earthquake damage in easily replaceable parts. Friction dampers typically satisfy both requirements. These dampers are very versatile since they can be equipped in different structural arrangements. One of the most promising solutions is their application in the moment-resisting beam-to-column joints where they can effectively dissipate the seismic energy and limit plastic deformations into easily replaceable elements. Furthermore, their resistance and deformation capacity can be easily designed without interfering with the structural geometry, thus allowing the standardisation of friction connections for a wide range of beam-to-column assemblies. The current work presents a parametric study based on finite element (FE) simulations of steel beam-to-column joints equipped with a set of five predefined friction dampers specifically conceived to cover the most representative range of profiles used in Eurocode-compliant multi-storey moment resisting frames. The FE models were calibrated against recent experimental tests performed by the authors in a former study. The analyses were aimed at extending these experimental results, investigating the local behaviour of the dampers and the connections as well as the influence of member scaling on the monotonic and hysteretic behaviour of each assembly. The results confirm that the non-linear performance of connections equipped with friction dampers is almost independent on the dimensions of the connected profiles, and it is fully replicable within a predefined range of geometrie

Lupus erythemateux dissemine sans anticorps antinucleaires et sans autres autoanticorps. [Disseminated lupus erythematosus without antinuclear antibodies or other autoantibodies]

Antinuclear antibodies (ANA) are found in the majority of patients with systemic lupus erythematosus (SLE). We report here the only documented case, out of a series of 38 patients, in which SLE was diagnosed in spite of the fact that we failed to demonstrate any type of autoantibodies. A 25-year-old black woman presented with 6 of the 11 criteria of the American Rheumatism Association for classification of SLE, between August 1984 and April 1985, i.e. malar rash, photosensitivity, arthritis, pleurisy and pericarditis, renal insufficiency and nephrotic syndrome, anemia and leukopenia. Renal biopsy revealed mesangial glomerulonephritis, tubulonephritis and many tubuloreticular inclusions in the capillary endothelium highly suggestive of SLE. Four ANA determinations were performed during the 8 months of observation which were all negative, as were all other antibodies (anti-nDNA, -Sm, -RPN, -Ro, -La). The outcome was very favourable under prednisone and cyclophosphamide. In the rare cases of ANA negative SLE (5-10%) photosensitive dermatitis is the prominent feature and renal or central nervous system involvement is less frequent. Those patients usually have other types of autoantibodies (especially anticytoplasmic) which was not the case in our patient. This indicates that the absence of autoantibodies does not rule out SLE