Lymphoid cell subclasses in rejecting renal allograft in the rat

We have quantitated the frequency of lymphoid cell subsets in rejecting renal allografts and in the spleen of the allograft recipient during drug-unmodified rejection in the rat. The number of inflammatory (white) cells in the graft was approximately similar to the number of white cells responding to the allograft in the recipient spleen. The inflammatory population of the graft consisted of lymphoid cells and mononuclear phagocytes, with increasing numbers of macrophages toward the end of rejection. Analysis of allograft cellular dispersates with monoclonal antibodies directed to the lymphoid cell subsets demonstrated that although the majority of allograft-infiltrating lymphocytes were T cells, a sizable B-cell proliferation and immunoglobulin synthesis was associated with the inflammatory response of rejection. Within the T-cell subset, the T suppressor/killer cells predominated in the graft whereas the predominant lymphoid cell subset responding to the allograft in the recipient spleen was the T helper cell.     

Purification of human vitamin K-dependent protein S and its limited proteolysis by thrombin

Vitamin K-dependent protein S exists in two forms in human plasma, namely as the free protein and in complex with C4b-binding protein [Dahlbäck & Stenflo (1981) Proc. Natl. Acad. Sci. U.S.A. 78, 2512-2516]. Now reported is a simple purification procedure for human protein S that includes barium citrate adsorption, DEAE-Sephacel chromatography and chromatography on Blue Sepharose. The yield was approx. 30% relative to the concentration of free protein S in plasma, which was found to be approx. 10 mg/l. Purified protein S migrated as a single-chain band on sodium dodecyl sulphate/polyacrylamide-gel electrophoresis under non-reducing conditions and as a doublet of Mr approx. 85 000 and 75 000 on reduction. A third band of Mr 16 000 was observed after electrophoresis of 125I-labelled protein S and radioautography of reduced samples. This band appears to be disulphide-linked to the 75 000-Mr chain before reduction. Thrombin converted the 85 000-Mr chain of protein S into a 75 000-Mr chain and an 8000-Mr fragment, the latter again being detectable only by radioautography of reduced samples. The 16 000-Mr fragment was not observed, suggesting its degradation by thrombin. Under non-reducing conditions, no change in apparent molecular weight of thrombin-treated protein S was observed, indicating disulphide linkage of the fragments. Thrombin also affected the mobility of protein S on agarose-gel electrophoresis in the presence of Ca2+, suggesting a decreased affinity to Ca2+ of the cleaved form of protein S as compared with the undegraded molecule. After activation of the complement system in human serum, protein S was found to be a constituent part of the complex formed by C4b-binding protein and component C4b.     

Combined application of misonidazole and piotron pions on mouse embryos

Mouse embryos on day 8 of gestation were irradiated with negative pions (12.5-100 rad) or 200 kV X-rays (12.5-150 rad). Misonidazole (MISO), a hypoxic cell radiosensitizer, was applied 30 min before exposure. On day 13 the fetuses were examined for lethality, growth retardation and malformation. No significant embryolethal effects were observed after irradiation alone in the dose range of 12.5-100 rad (X-rays or pions). However, MISO alone and in combination with radiation led to high rates of lethality. The frequency of growth retardation was significantly increased at 100 rad and in combined treatments at low radiation doses. MISO and irradiation with 50 rad and more induced complex damages consisting of multiple and severe malformations and growth retardation. The relative biological effectiveness (RBE) for teratogenic effects was 1.6. In conclusion, the combined application of MISO and radiation of different LET revealed a strong enhancing action compared to single treatments. The extent of enhancement depends on both radiation quality and dose.     

Lack of orthogonal particle assemblies and presence of tight junctions in astrocytes of the goldfish (Carassius auratus)

Summary Specific antibodies raised against a human 28 000 dalton cerebellar calcium-binding protein (CaBP) were used in an immunocytochemical study during development of the rat cerebellum. Both light and electron microscopy showed (1) that labelling was entirely restricted to the Purkinje cells, (2) that it appeared very early in Purkinje cell development, (3) that the entire cell was labelled from the tip of the smallest dendrites to the axonal terminals, and (4) that with increasing age, the immunoreaction appeared to be progressively restricted to the cell and organelle membranes.     

Serotonin-like immunoreactivity in the optic lobes of three insect species

The cellular localization of 5-HT in the optic lobes of three insect species was assayed with the use of antibodies raised against 5-HT. In Schistocerca, Periplaneta, and Calliphora all neuropil regions of the optic lobe, the lamina, medulla and lobula, contain 5-HT-immunoreactive varicose fibres in different patterns, like columns and layers. Such fibres also connect the lobula to neuropil in the lateral protocerebrum. In Calliphora also 5-HT-positive fibres of the medulla and lobula plate have projections to the lateral protocerebrum, whereas the origin of the lamina fibres is not certain. In all species the processes displaying 5-HT-like immunoreactivity appear to be derived from a relatively small number of cell bodies, each neuron thus having processes over a large volume of the neuropil of the optic lobe in different layers.     

Dynamics of the cytoskeleton in Amoeba proteus

Fluorescein-labeled muscle actin was microinjected into Amoeba proteus and followed during intracellular redistribution by means of the image-intensification technique. The fully polymerization-competent protein becomes part of the endogenous actomyosin system undergoing dynamic changes over time periods of several hours. Single-frame analysis of long-term sequences enabled the direct demonstration of both the contractile activities and morphological transformations of microfilaments in normally locomoting, immobilized and phagocytozing specimens. In normally locomoting cells the filament layer undergoes continuous changes in spatial distribution depending on the actual pattern of cytoplasmic streaming and cell shape. The highest degree of differentiation is always maintained in the intermediate region between the front and the uroid, thus indicating this segment of the cortex to be the most important site in generating motive force for pseudopodium formation and ameboid movement. In immobilized cells contracted by the application of ruthenium red or relaxed by different anesthetics, the filament layer forms a continuous thick sheath beneath the cell surface or becomes completely disintegrated. In phagocytozing cells the local polymerization of actin at the tip of pseudopodia forming the food-cup and around the nascent phagosome points to a significant participation of the actomyosin system in the process of capturing and constricting prey organisms. Although our results provide clear evidence for the overall importance of motive force generation according to the hydraulic pressure theory, some motile phenomena exist in Amoeba proteus that cannot exclusively be explained by this mechanism.     

Lateral Transport of Ions into the Xylem of Corn Roots: II. Evaluation of a Stelar Pump

When an excised corn (Zea mays) root pretreated with chloride was exposed for 10 minutes to pulse labeling with ³⁰Cl and then transferred to unlabeled chloride, the activity in the xylem exudate reached a maximum about 4 minutes after pulse labeling was discontinued and then declined sharply. The rate at which labeled chloride was transported across the root into the xylem and basipetally therein was on the order of 75 to 250 centimeters per hour. Consequently, symplasmic movement of chloride in corn roots is fast and may not be rate-limiting in transfer from the root surface to the xylem. Experiments on pulse labeling with ²²Na gave similar results. A large fraction of the absorbed ²²Na was not translocated into the exudate but was tightly sequestered in a cell compartment, probably the vacuole.