Isolation and quantification of soluble Alzheimer's beta-peptide from biological fluids.

Cerebral deposition of the beta-amyloid peptide (A beta) is an invariant feature of Alzheimer's disease. Since the original isolation and characterization of A beta (ref. 1) and the subsequent cloning of its precursor protein, no direct evidence for the actual production of discrete A beta has been reported. Here we investigate whether A beta is present in human biological fluids using antibodies specific for an epitope within A beta that spans the site of normal constitutive cleavage. These antibodies were used to construct a sandwich-type enzyme-linked immunosorbent assay that detects A beta in cerebrospinal fluid, plasma and conditioned medium of human mixed-brain cells grown in vitro (see also ref. 14). By affinity chromatography, we have purified and sequenced A beta and a novel A beta fragment from human cerebrospinal fluid and conditioned medium of human mixed-brain cell cultures. These findings demonstrate that A beta is produced and released both in vivo and in vitro. These observations offer new opportunities for developing diagnostic tests for Alzheimer's disease and therapeutic strategies aimed at reducing the cerebral deposition of A beta.     

The secreted form of the Alzheimer's amyloid precursor protein with the Kunitz domain is protease nexin-II

The A4 protein (or beta-protein) is a 42- or 43-amino-acid peptide present in the extracellular neuritic plaques in Alzheimer's disease and is derived from a membrane-bound amyloid protein precursor (APP). Three forms of APP have been described and are referred to as APP695, APP751 and APP770, reflecting the number of amino acids encoded for by their respective complementary DNAs. The two larger APPs contain a 57-amino-acid insert with striking homology to the Kunitz family of protease inhibitors. Here we report that the deduced amino-terminal sequence of APP is identical to the sequence of a cell-secreted protease inhibitor, protease nexin-II (PN-II). To confirm this finding, APP751 and APP695 cDNAs were over-expressed in the human 293 cell line, and the secreted N-terminal extracellular domains of these APPs were purified to near homogeneity from the tissue-culture medium. The relative molecular mass and high-affinity binding to dextran sulphate of secreted APP751 were consistent with that of PN-II. Functionally, secreted APP751 formed stable, non-covalent, inhibitory complexes with trypsin. Secreted APP695 did not form complexes with trypsin. We conclude that the secreted form of APP with the Kunitz protease inhibitor domain is PN-II.     

Ca2+-dependence and metabolic status of an obligate thermophile,Thermoactinomyces vulgaris,under shake culture conditions

Summary Ca²⁺ stimulates germination ofT. vulgaris spores. There is a higher mycelial yield as well as higher protein, DNA, RNA and free Pi content in cultures grown in the presence of Ca²⁺ as compared to those grown in the absence of this divalent cation.Grateful thanks are due to Professor R. P. Roy for providing the necessary facilities. V. P. S. acknowledges with thanks the receipt of a Post Doctoral Research Fellowship of the Council of Scientific and Industrial Research, New Delhi.     

Effect of starvation on the concentration of ascorbic acid in the pedipalp muscle of the scorpionPalamnaeus bengalensis

Zusammenfassung Bei 12 Tage hungernden Skorpionen (Palamnaeus bengalensis) wurde die Ascorbinsäure-Konzentration im Pedipalpen-Muskel mit 2, 4-Dinitrophenyl nachRoe bestimmt und dabei eine signifikante Abnahme der Ascorbinsäure festgestellt.     

Mechanism of action of boseimycin

Zusammenfassung Unmittelbar nach Zugabe von Boseimycin zuB. subtilis werden Wachstum und Proteinsynthese verhindert. DNA und RNA werden erst später beeinflusst. Die hemmende Wirkung von Boseimycin auf die behandelten Zellen ist nach Waschung mit Phosphatpuffer reversibel.     

A simplified assay for cyclic AMP using protein kinase binding

Summary The protein kinase binding assay for cAMP was modified by substitution of adsorption by QAE cellulose for the membrane filtration. This modification obviates the variation of recovery of cAMP with the volume of buffer used to wash the filter. The assay is reproducible and technically simpler than those currently employed.Acknowledgment. This work was partially supported by grants HL-16583 and HL-18827 from the National Heart and Lung Institute.