Inside-out membrane vesicles isolated from spinach thylakoids.

Inside-out thylakoid vesicles have been separated from right-side-out material after press disruption of chloroplast lamellae. The sepration was obtained by partitionin an aqueous dextran-polyethylene glycol two-phase system, a method which utilizes differences in surface properties for separation of membrane particles. The isolated thylakoid vesicles showed the following inside-out properties: (1) light-induced reversible proton extrusion into the surrounding medium when supplied with the Photosystem II electron acceptor phenyl-p-benzoquinone; (2) a pH rise in the internal phase accompanying the external proton release, (3) sensitivity to trypsin treatment different from that of thylakoid membranes of normal orientation; (4) concave EF and convex PF freeze-fracture faces.     

Purification and characterization of a low molecular weight 1,4-beta-glucan glucanohydrolase from the cellulolytic fungus Trichoderma viride QM 9414

A low molecular weight 1,4-beta-glucan glucanohydrolase (endoglucanase) (1,4-(1,3;1,4)-beta-D-glucan 4-glucanohydrolase, EC 3.2.1.4) has been isolated from culture filtrates of the fungus Trichoderma viride QM 9414 by a two-step procedure of gel filtration and ion-exchange chromatography. The isolated enzyme appeared homogeneous upon polyacrylamide gel electrophoresis at pH 2.9, isoelectric focusing in a polyacrylamide gel slab, sedimentation equilibrium analysis and chromatography of the reduced and alkylated enzyme on a column of Sepharose 6B in 6 M guanidine - HCl. A molecular weight was calculated at approx. 20 000 and the isoelectric point was determined at pH 7.52. The purified enzyme was not a carbohydrate-containing protein.     

Cloning of murine transformed cell lines in suspension culture with efficiencies near 100%

Addition of 3 × 10⁶ thymus cells from either syngeneic, allogeneic or xenogeneic animals increases the cloning efficiencies of murine thymomas (EL-4, WC-2), B-lymphomas (McPC 1748, 38C-13), Abelson-virus transformed cell lines (F and K), mastocytomas (P815), myelomas (AbPC22, X63-AG8, 5563, MOPC 104 E, RFC 5, W 3469) and hybrids of myelomas and normal B-lymphocytes (Sp-1), all adapted to tissue culture, to near 100%. Thymus cells also increase the efficiencies of growth initiation in primary in vitro cultures of myeloma tumor cells (S117) transplanted in vivo, and of cells fused between the azaguanine-resistant X63-AG8 myeloma cell line and normal, LPS-stimulated B-lymphocyte blasts.     

Inhibition of gastric acid secretion in dogs by neurotensin

Neurotensin is a tridacapeptide which has been isolated from bovine hypothalamus. The action of synthetic neurotensin was studied on gastric acid secretion in dogs provided with gastric pouches. Intravenously infused neurotensin, 50 ng × kg^?1 × min^?1, was found to produce a considerable inhibition of pentagastrin stimulated gastric acid secretion. On the other hand, there was no sign of inhibition of histamine induced gastric acid secretion. The experiments show that neurotensin, isolated from the central nervous system is a potent gastric secretory inhibitor and that it has a selective action in inhibiting gastric acid responses to pentagastrin but not to histamine.     

Allergic delayed skin reactions from lipid fractions of trichophytin.

Crude trichophytin was fractionated to find out if its lipid fraction could cause inflammatory delayed allergic skin reactions in dermatophyte-sensitized guinea pigs. The following fractions were obtained: polysaccharide-peptide, total lipids, total lipids without free fatty acids and free fatty acids. The crude trichophytin and polysaccharide-peptide fraction gave rise to strong and equal allergic delayed skin reactions after 24 h. The total lipids gave statistically significant weaker, but clearly positive reactions, and of the same degree as the free fatty acid fraction. The total lipids without free fatty acids did not produce reactions in the sensitized animals, indicating that free fatty acids are responsible for the allergic skin reactions. In some cases the free fatty acids showed comparatively intense reactions. It can be concluded that free fatty acids are antigenic substances that are, sometimes, involved in the allergic delayed skin reactions in dermatophytosis.     

Prevalence of primary and secondary hypertension: studies in a random population sample.

The prevalence of primary and secondary hypertension was determined in a random sample of 7455 Swedish men aged 47 to 54 years. Three hundred and sizty-one men were undergoing treatment for hypertension. Seven hundred and ninety-eight men who had blood pressures above 175/115 mm Hg at preliminary screening were recalled for further blood pressure measurements. Those on treatment and all the untreated men whose blood pressures were still over 175/115 mm Hg then underwent extensive investigation for secondary hypertension. Renal parenchymal hypertension was found in 25 (3-6%) patients, renovascular hypertension in four (0-6%), and other forms of secondary hypertension in 11 (1-6%). The investigation led to surgical treatment in only two cases (0-3%). The low prevalence of secondary hypertension, especially surgically curable forms of hypertension, makes routine screening for these cases unnecessary, at least when patients with hypertension have been found at screening. These data must be taken into account in planning community control programmes in hypertension.     

Characterization of surface glycoproteins of mouse lymphoid cells

We have labeled exposed surface glycoproteins of mouse lymphoid cells by the galactose oxidase-tritated sodium borohydride technique. The labeled glyco-proteins were separated by polyacrylamide slab gel electrophoresis and visualized by autoradiography (fluorography). The major thymocyte surface proteins have molecular weights of 170,000 and 125,000. Thymocytes from TL antigen-positive mouse strains showed an additional band with a molecular weight of 27,000. Highly purified T lymphocytes contain two major surface glycoproteins with molecular weights of 180,000 and 125,000. Purified B lymphocytes have one major surface glycoprotein with a molecular weight of 210,000. When T lymphocytes are stimulated in vitro by concanavalin A or phytohemag-glutinin, the major proteins characteristic of T cells are relatively weakly labeled, but new components of lower molecular weights appear on the cell surface. A similar change is seen in B lymphocytes stimulated by Escherichia coli lipopolysaccharide. T lymphoblasts isolated from mixed lymphocyte cultures show a slightly different surface glycoprotein pattern. A polypeptide with a molecular weight of 57,000, which was labeled without enzymatic treatment by tritiated sodium borohydride alone, is strongly labeled in proliferating cells.     

Amino acid sequence at the phosphorylated site of rat liver pyruvate kinase

One dominating peptic phosphopeptide, Asx-Thr-Lys-Gly-Pro-Glx-Ile-Glx-Thr-Gly-Val-Leu-Arg-Arg-Ala-(³²P)SerP-Val-Ala-Glx-Leu, was obtained from rat liver pyruvate kinase (type L) phosphorylated by cyclic 3′,5′-AMP-stimulated protein kinase from the same tissue. The sequence around the phosphorylated serine residue is similar to that of a corresponding but smaller peptic phosphopeptide previously isolated from pig liver (type L) pyruvate kinase, Leu-Arg-Arg-Ala-(³²P)SerP-Leu.