Complex formation between plasminogen activator inhibitor 1 and vitronectin in purified systems and in plasma.

Functionally active PAI-1 is bound to a discrete binding or carrier protein in plasma, which was recently identified as vitronectin. In the present study, the interaction between PAI-1 and vitronectin has been studied in purified systems and in plasma by agarose gel electrophoresis using non-denaturing conditions and by crossed immunoelectrophoresis using an antiserum produced towards purified PAI-1/vitronectin complex. Both methods revealed a clearly distinguishable complex with electrophoretic mobility in between the parent molecules. Virtually all of the purified vitronectin, which did not contain any appreciable amounts of polymerized material, and almost all of the vitronectin in plasma, had the capacity to form a complex with PAI-1. The results suggested a stoichiometry of 1:1 as the most likely ratio between the two molecules in the complex. In contrast to functionally active PAI-1, latent or chloramine T-inactivated PAI-1 did not form such a complex with vitronectin.     

A simplified screening test for the diagnosis of allergy.

The Quidel allergy screen is a relatively rapid (less than 2 hours) multiallergen dipstick method for detecting specific immunoglobin E antibodies in serum. It was developed to answer the need of primary physician nonspecialists in allergy for a convenient in-office screening test for diagnosing allergy. The new test was evaluated against the benchmark diagnostic skin tests and the radioallergosorbent serologic tests for sensitivity, specificity, accuracy, and technical feasibility in an office setting. It was found that while the Quidel allergy screen lacks the specificity of the standard tests, its overall sensitivity, as defined by the percentage of patients with positive skin reactions who also tested positive with the Quidel screen (68%), its ease of use, and its rapidity warrant its consideration as a screening tool for confirming a possible case of allergy.     

Is methyl-branching in alpha-tocopherol's "tail" important for its in vivo activity? Rat curative myopathy bioassay measurements of the vitamin E activity of three 2RS-n-alkyl-2,5,7,8-tetramethyl-6-hydroxychromans

The vitamin E activity of the acetates of three 2RS-n-alkyl-2,5,7,8-tetramethyl-6-hydroxychroman analogs of alpha-tocopherol have been measured and compared directly with all-rac-alpha-tocopheryl acetate, or indirectly via 2R,4'R,8'R-alpha-tocopheryl acetate, using the rat curative myopathy, plasma pyruvate kinase assay. The analogs with alkyl chain lengths of 11 and 13 carbons have activities which not only do not differ significantly (p greater than 0.05) from each other but also do not differ from that of all-rac-alpha-tocopheryl acetate. This finding indicates that methyl branching in the phytyl tail at the 4', 8', and 12' positions has little if any influence upon vitamin E activity. Thus physical interactions involving the methyl branches of the phytyl tail and the polyunsaturated moieties of membrane phospholipids are unimportant in vivo, insofar as this bioassay is concerned. However, the length of the hydrocarbon tail is important. This is indicated by the result obtained with the acetate of the analog with an alkyl chain length of 15 carbon atoms which had only 15% of the activity of 2R,4'R,8'R-alpha-tocopheryl acetate, i.e., 22% of the activity of all-rac-alpha-tocopheryl acetate since this form is 1.47 times less active than 2R,4'R,8'R-alpha-tocopheryl acetate in the curative myopathy bioassay (Weiser, Vecchi, & Schlachter, Internat. J. Vit. Nutr. Res. 55:149-158, 1985).     

The quantitative analysis of lipopolysaccharide antigen in the blood serum of patients with salmonellosis by using complement-bound liposome lysis]

Titration of group B Salmonella O-antigen in the blood sera of patients and donors was carried out by means of the complement-dependent lysis of liposomes sensitized with S. typhimurium LPS. Good correlation (r = 0.95) of the levels of S. typhimurium somatic O-antigen in the patients' sera determined by liposomal immunoassay and aggregate hemagglutination test was established. The concentration of the antigens in the tested samples was within 0.5-50 micrograms/ml. Statistical analysis of the results obtained by liposomal immunoassay techniques demonstrated differences in the distribution functions for the blood sera of patients with different diseases and of donors.     

Melanin concentrating hormone. III. Melanin concentrating hormone (MCH): the message sequence

Melanin concentrating hormone (MCH) is a heptadecapeptide synthesized by the hypothalamus and secreted by the neurohypophysis of the teleost pituitary gland. MCH stimulates melanosome aggregation within teleost melanocytes but also exhibits MSH-like (melanosome dispersing) activity on tetrapod (frog and lizard) melanocytes. We have synthesized a number of MCH analogues to determine the essential features of the primary structure necessary to stimulate either melanosome aggregation or dispersion in fish or tetrapod melanocytes, respectively. An analysis of the potencies and actions of these analogues on vertebrate melanocytes is provided and demonstrates that the two activities have different structural requirements.     

Platinum Polyoxoniobates Form Adducts with DNA

Russian Journal of Bioorganic Chemistry - Platinum complexes are among the most commonly prescribed drugs in cancer therapy but show significant toxicity to healthy tissues as a side effect....     

Change of liver metabolism of 1,2-dibromoethane during simultaneous treatment with carbon tetrachloride

The combination of carbon tetrachloride (CCl₄) and 1,2-dibromoethane (DBE) in isolated rat hepatocytes led to a significant potentiation of both lipid peroxidation and of plasma membrane damage observed after a single treatment with CCl₄. Such a synergistic effect appeared to be related to the CCl₄-induced shift of DBE metabolism from the cytosolic conjugation with glutathione towards the microsomal transformation into toxic intermediates. In fact, CCl₄ significantly inactivated hepatocyte total GSH-transferase, i.e. the DBE detoxification pathway. Furthermore, while the microsomal metabolism of CCl₄ was not affected by the simultaneous presence of DBE, the amount of DBE reactive metabolities covalently bound to hepatocyte protein was significantly enhanced in the presence of CCl₄.     

Dynamics of functional reciprocal connections between cerebral motor cortex neurons under stimulation in cats

Activity was recorded from neurons belonging to the representation of the forelimb in the motor cortex (sulcus cruciatus, L 7–9 mm) using multiple multi-channel/barrel electrodes during acute experiments on cats. Cross-correlation analysis of impulse trains was adopted to investigate dynamics of interneuronal connections during passive flexion and electrical stimulation of the limb contralateral to the recording site. It was found that neither passive bending nor electrical stimulation of the limb leads to a significant increase in the total number of direct relationships between cortical neurons. At the same time, passive flexion does produce a considerable decrease in the number of instances of both inputs operating in neighboring neurons (50–100 µm apart) and an increase in cells located further (between 100 and 400 µm) apart. Some increase in the number of direct inhibitory interactions between neighboring neurons was observed during electrical stimulation.Institute of Higher Nervous Activity and Neurophysiology, Academy of Sciences of the USSR, Moscow. Nentskii Institute of Experimental Biology, Warsaw, Poland. Center of Experimental and Clinical Medicine, Warsaw, Poland. Translated from Neirofiziologiya, Vol. 23, No. 1, pp. 73–80, January–February, 1991.     

Biosynthesis of the trichothecene 3-acetyldeoxynivalenol. Identification of the oxygenation steps after isotrichodermin

Upon feeding an excess of the substrate isotrichodermin, five tricyclic metabolites accumulated in Fusarium culmorum cultures. These compounds were also identified as transient intermediates of trichothecene biosynthesis by kinetic pulse labeling. Their structures were characterized by spectroscopic techniques (1H NMR, 13C NMR, 2H NMR, and nuclear Overhauser effect difference experiments) as: 1, 15-deacylcalonectrin; 2, calonectrin; 3, 7-hydroxyisotrichodermin; 4, 8-hydroxyisotrichodermin; and 5, 7, hydroxycalonectrin. Four of these metabolites (1-4) were rigorously proven to be biosynthetic precursors to 3-acetyldeoxynivalenol. Indeed, their deuteriated derivatives were shown to be incorporated very efficiently into 3-acetyldeoxynivalenol by 2H-NMR. In addition, our experimental data suggests that the first oxygenation step after isotrichodermin is at C-15, producing 15-deacylcalonectrin.