Immunolocalization of alpha and beta chains of human chorionic gonadotropin,placental lactogen and pregnancy-specific beta-glycoprotein in term placenta by a touch preparation method

Summary Touch preparations of human placenta yield cells retaining antigenic reactivity to immunoperoxidase stains for and chains of human chorionic gonadotropin, placental lactogen, and pregnancy-specific glycoprotein. This method is a rapid and simple alternative to conventional frozen and paraffin-embedded sections for detection of placental peptides.     

Plasmid-encoded copper resistance and precipitation by Mycobacterium scrofulaceum.

A copper-tolerant Mycobacterium scrofulaceum strain was able to remove copper from culture medium by sulfate-dependent precipitation as copper sulfide. Such precipitation of copper sulfide was not observed in a derivative that lacks a 173-kilobase plasmid. In addition, the plasmid-carrying strain has a sulfate-independent copper resistance mechanism.     

Effect of nutritional insufficiency on cell proliferation in the matrix zones of the cerebellar anlage in mice

The work has been performed on 62 CBA mice. In the ventricular zone and in the external granular layer of the cerebellar anlage of embryos (13-17 days of the intrauterine development) mitotic index, labelled nuclei index, part of labelled mitoses have been counted. Parameters of the mitotic cycle of the matrix cells have been calculated by means of the graphic method. The proliferative pool value has been calculated. At malnutrition the cerebellar anlage structure retards in its maturation from the norm. For the matrix zones of the cerebellar anlage, higher indices of the proliferative activity are specific. At the same time, duration of the mitotic cycle of the matrix cells increases by 15-17%. It is possible, that retardation of histogenesis of the mouse cerebellar anlage, when developing under conditions of alimentary insufficiency depends on decreased rate of cell proliferation, as a result of prolonged mitotic cycle of the matrix cells.     

Effect of beta-hydroxybutyrate and acetoacetate on insulin and glucagon secretion from perfused rat pancreas

To elucidate the physiological significance of ketone bodies on insulin and glucagon secretion, the direct effects of beta-hydroxybutyrate (BOHB) and acetoacetate (AcAc) infusion on insulin and glucagon release from perfused rat pancreas were investigated. The BOHB or AcAc was administered at concentrations of 10, 1, or 0.1 mM for 30 min at 4.0 ml/min. High-concentration infusions of BOHB and AcAc (10 mM) produced significant increases in insulin release in the presence of 4.4 mM glucose, but low-concentration infusions of BOHB and AcAc (1 and 0.1 mM) caused no significant changes in insulin secretion from perfused rat pancreas. BOHB (10, 1, and 0.1 mM) and AcAc (10 and 1 mM) infusion significantly inhibited glucagon secretion from perfused rat pancreas. These results suggest that physiological concentrations of ketone bodies have no direct effect on insulin release but have a direct inhibitory effect on glucagon secretion from perfused rat pancreas.     

The isolation and characterisation of a cDNA clone for human lecithin:cholesterol acyl transferase and its use to analyse the genes in patients with LCAT deficiency and fish eye disease

We have isolated cDNA clones coding for human lecithin:cholesterol acyl transferase (LCAT) from a liver-specific cDNA library by the use of two oligonucleotide probes based on the protein sequence. The clones span the sequence coding for the entire secreted LCAT, the 3' untranslated sequence and 12 amino acids of the signal peptide. The peptide sequence contains the conserved active site of serine lipases within a hydrophobic domain, flanked by a possible amphipatic alpha-helix. Only one gene for LCAT could be detected in genomic blots. We have used the cDNA as a probe to analyse the LCAT gene in patients suffering from LCAT deficiency and fish eye disease. No rearrangements or abnormal gene fragments were detected in these patients.     

High affinity binding of human interleukin 4 to cell lines

Purified human recombinant interleukin 4 (IL-4) was radio iodinated to high specific radioactivity without loss of biological activity. 125I-IL-4 bound specifically to the Burkitt lymphoma Jijoye cells and other cell lines. Jijoye cells showed a high affinity for 125I-IL-4 (Kd approximately equal to 7 10(-11) M) and displayed 1200-1400 specific receptors per cell at 4 degrees C or 37 degrees C. The equilibrium dissociation constant (Kd) corresponds to the IL-4 concentration which induces 50% maximal expression of the low affinity IgE receptor (Fc epsilon RL/CD23) on Jijoye cells. At 4 degrees C the rate constant of association K1 is 1.7 x 10(6) M-1 s-1 and the rate contant of dissociation k -1 is 1.3 x 10(-4) s-1 (t 1/2 = 91 min.) No human recombinant lymphokines other than IL-4 were able to compete for the binding of 125I-IL-4 to its receptor.     

Down-regulation of atrial natriuretic factor receptors and correlation with cGMP stimulation in rat cultured vascular smooth muscle cells

The relationship between the binding of 125I-labeled rat ANF and the responsiveness in cGMP production of ANF receptors were examined in cultured rat thoracic smooth muscle cells after preexposure with the peptide. Binding assay of 125I-labeled ANF showed a specific, reversible and saturable binding with a KD value of 3.1 +/- 0.3 10(-10) M and a maximum binding (Bmax) of 240 +/- 30 fmol/10(6) cells. Pretreatment of the cells with increasing concentrations of unlabeled ANF (10(-9) M to 10(-7) M) resulted in a dose-dependent decrease of the number of binding sites without a change in the affinity. This effect was clearly associated with a desensitization of ANF-induced cGMP production.     

Molecular cloning, cDNA structure and deduced amino acid sequence for a type I regulatory subunit of cAMP-dependent protein kinase from human testis

A 1.5 kilobase (kb) cDNA clone containing the entire coding region for a regulatory subunit of type I cAMP-dependent protein kinase (RI) was isolated from a human testis cDNA library. The cDNA clone encodes a protein of 381 amino acids that shows 98% and 97% homology to the bovine skeletal muscle RI and rat brain RI, respectively. Northern blot analysis demonstrates two major mRNA-species (1.5 and 3.0 kb) in human testis and one mRNA-species (3.0 kb) in human T-lymphocytes.     

Inhibition of tubulin self-assembly and tubulin-colchicine GTPase activity by guanosine 5'-(gamma-fluorotriphosphate)

The inhibitory effects of guanosine 5'-(gamma-fluorotriphosphate) [GTP(gamma F)] on both the polymerization and the colchicine-dependent GTPase activity of calf brain tubulin have been studied. The results demonstrate that this analogue of GTP, with a fluorine atom on the gamma-phosphate, is a reversible competitive dead-end inhibitor of the colchicine-induced GTPase activity with a K1 value of (1.8 +/- 0.6) X 10(-4) M. GTP(gamma F) did not promote assembly of tubulin from which the E-site guanine nucleotide had been removed. It binds to the exchangeable nucleotide site competitively with respect to GTP, diminishing both the rate and extent of tubulin polymerization. Treatment in terms of the Oosawa-Kasai model of the inhibitory effect of GTP(gamma F) on the assembly led to a value of Kdis = 1.1 X 10(-6) M for the complex GTP(gamma F)-tubulin. This analogue does not bind to the postulated third site. The growing of tubulin polymers at 37 degrees C was arrested by GTP(gamma F), and only limited depolymerization was induced by the addition of this analogue after assembly in the presence of GTP. This result confirms that the E-site is blocked in the polymer and that this analogue can bind only to the ends of the polymers. Sedimentation velocity and circular dichroism studies showed that the conformation of the tubulin-GTP(gamma F) complex is not identical with that of tubulin-GTP. This is caused by the replacement of the hydroxyl group in the gamma-phosphate by the fluorine group, which have 2.20- and 1.35-A van der Waals radii, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)