Isolation and characterization of CA XIV, a novel membrane-bound carbonic anhydrase from mouse kidney.

Carbonic anhydrase (CA) is involved in various physiological processes such as acid-base balance and transport of carbon dioxide and ions. In this study, we have succeeded in the isolation of a novel CA from the mouse kidney by use of the signal sequence trap method. It is a 337-amino acid polypeptide with a calculated molecular mass of 37.5 kDa, consisting of a putative amino-terminal signal sequence, a CA domain, a transmembrane domain, and a short hydrophilic carboxyl terminus, which we designated CA XIV. The CA domain of CA XIV is highly homologous with those of known CAs, especially extracellular CAs including CA XII, IX, VI, and IV. The expression study of an epitope-tagged protein has suggested that CA XIV is located on the plasma membrane. When expressed in COS-7 cells, CA XIV exhibits CA activity that is predominantly associated with the membrane fraction. By Northern blot analysis, the gene expression of CA XIV is most abundant in the kidney and heart, followed by the skeletal muscle, brain, lung, and liver. In situ hybridization has revealed that, in the kidney, the gene is expressed intensely in the proximal convoluted tubule, which is the major segment for bicarbonate reabsorption and also in the outer border of the inner stripe of the outer medulla. In conclusion, we have cloned a functional cDNA encoding a novel membrane-bound CA. This study will bring new insights into our understanding of carbon dioxide metabolism and acid-base balance.     

Rac1 inhibits TNF-alpha-induced endothelial cell apoptosis: dual regulation by reactive oxygen species.

Reactive oxygen species (ROS) have been implicated as mediators of tumor necrosis factor-alpha (TNF) -induced apoptosis. In addition to leading to cell death, ROS can also promote cell growth and/or survival. We investigated these two roles of ROS in TNF-induced endothelial cell apoptosis. Human umbilical vein endothelial cells (HUVECs) stimulated with TNF produced an intracellular burst of ROS. Adenoviral-mediated gene transfer of a dominant negative form of the small GTPase Rac1 (Rac1N17) partially suppressed the TNF-induced oxidative burst without affecting TNF-induced mitochondrial ROS production. HUVECs were protected from TNF-induced apoptosis. Expression of Rac1N17 blocked TNF-induced activation of nuclear factor-kappa B (NF-kappaB), increased activity of caspase-3, and markedly augmented endothelial cell susceptibility to TNF-induced apoptosis. Direct inhibition of NF-kappaB through adenoviral expression of the super repressor form of inhibitor of kappaBalpha (I-kappaB S32/36A) also increased susceptibility of HUVECs to TNF-induced apoptosis. Rotenone, a mitochondrial electron transport chain inhibitor, suppressed TNF-induced mitochondrial ROS production, proteolytic cleavage of procaspase-3, and apoptosis. These findings show that Rac1 is an important regulator of TNF-induced ROS production in endothelial cells. Moreover, they suggest that Rac1-dependent ROS, directly or indirectly, lead to protection against TNF-induced death, whereas mitochondrial-derived ROS promote TNF-induced apoptosis.     

Acetic, propionic, and oleic acid as the possible factors influencing the predominant residence of some species of Propionibacterium and coagulase-negative Staphylococcus on normal human skin

The minimum inhibitory concentration (MIC) of acetic and propionic acid for resident bacteria on normal human skin, such as Propionibacterium acnes and Staphylococcus epidermidis, was 25 mg/mL or more at any pH tested (pH 5.5-6.8). While the MIC of these acids for most of the transient bacteria was markedly decreased by lowering the pH of the media and at pH 5.5, the mean pH value of the normal human skin, the MIC was 6.25 mg/mL or less. The MIC of oleic acid for some strains of Gram-positive transient bacteria of Streptococcus, Micrococcus, or Bacillus was 100 micrograms/mL or less at all pH's tested. Staphylococcus aureus was resistant to this acid at pH 6.8, but became as sensitive as Streptococcus when the pH was lowered. The growth of P. acnes, the most predominant resident bacterium, was enhanced markedly and reached a maximum level at 6.25 mg/mL of propionic acid, 12.5 mg/mL of acetic acid, and 50-100 micrograms/mL of oleic acid. On the basis of these results, we presumed that acetic, propionic, and oleic acids are factors influencing the predominant residence of some species of Propionibacterium and coagulase-negative Staphylococcus on normal human skin.     

Growth Characteristics in Cultured Cucumber Tissues Infected with Hop Stunt Viroid

Leaf disks from hop stunt viroid (HSVd)-infected cucumber plants and healthy controls were cultured in vitro under different auxin/cytokinin regimes. Amounts of tissue growth and root formation were consistently reduced as a result of HSVd infection. Histological observations indicated that anomalies in the distribution of peripheral meristems and tracheary elements associated with cambial cells might be involved in the hypoplastic syndrome incited by HSVd.     

Discovery of novel motilin antagonists: Conversion of tetrapeptide leads to orally available peptidomimetics

We successfully discovered peptidomimetic motilin antagonists (17c and 17d) through the improvement of physicochemical properties of a tetrapeptide antagonist (2). Furthermore, with oral administration and based on motilin antagonistic activity, both compounds suppressed motilin-induced colonic and gastric motility in conscious dogs.     

Nuclear histones of unfertilized sea urchin eggs

Histones have been isolated from the nuclei of unfertilized eggs of the sea urchin Strongylocentrotus purpuratus. The electrophoresis of these histones exhibits a pattern different from that of the sperm or embryo of the same species.