Mechanism of the binding of 2-(4'-hydroxyphenylazo)benzoic acid to bovine serum albumin

The mechanism of the binding of 2-(4'-hydroxyphenylazo)benzoic acid (HABA) to bovine serum albumin was studied by relaxation methods as well as the binding isotherm using gel chromatography. A single relaxation was observed over a wide range of HABA concentration except at the extremes of high concentration where another slow process was observed. The concentration dependence of the reciprocal relaxation time of the fast process decreased monotonically with increase in concentration of HABA at constant polymer concentration. The data were analyzed on the basis of Brown's domain structure model and were found to be consistent with a sequential binding mechanism. The azohydrazon tautomerism of HABA was identified with the intramolecular step of the complex. The activation parameters of the step, determined from the temperature dependence of the relaxation time of the fast process, showed that this step is rate limited by an enthalpy barrier in both forward and backward directions. Comparison of the activation parameters with those of other serum albumin-ligand systems suggests that there is an enthalpy-entropy compensation in the activation process of the intramolecular step with the compensation temperature at about 270 K; the enthalpy-entropy compensation is thought to be related to the hydrophobic nature of the ligand.     

Further new species of the plant bug genus Campylomma Reuter from the Oriental Region (Heteroptera: Miridae: Phylinae: Nasocorini)

The fauna of the nasocorine plant bug genus Campylomma Reuter from the Oriental Region, including subtropical Japanese Ryukyu Islands (Okinawa Island of Southwest Islands-group) and Taiwan is updated. Three new species are herein described, C. astica n. sp. (from Okinawa and Taoyuan, Taiwan), C. hibiscicola n. sp. (Bangkok, Thailand) and C. nanrenana n. sp. (Pingtung, Taiwan). Of these, C. astica and C. hibiscicola, were observed to have cryptic habitat-preference, inhabiting bracts, stipules or flower buds of the sea (or coastal) hibiscus, Hibiscus tiliaceus (L.) (Malvaceae), planted for landscaping at urbanized zones. An updated checklist of the 22 Oriental Campylomma species is provided.     

Molecular species of platelet-activating factor generated by human neutrophils challenged with ionophore A23187

Two species of platelet-activating factor (PAF), 1-hexadecyl- and 1-octadecyl-2-acetyl-sn-glycero-3-phosphocholine (C16 = 0 AGEPC and C18 = 0 AGEPC) were detected in ionophore A23187-stimulated human neutrophils. The amount of AGEPC in 1 x 10(7) neutrophil cells was 80 +/- 26 pmol (mean +/- standard error) with a range of 14 to 223 pmol (n = 8), and it consisted of 80% of the C16 = 0 species and 20% of the C18 = 0 species. Most of the AGEPC derived from ionophore-treated neutrophils remained cell associated rather than being secreted into the medium, even when the medium contained ample albumin protein, which can trap AGEPC. These results were obtained by a technique of gas chromatography-mass spectrometry coupled with selected ion monitoring.     

Production of platelet-activating factor by washed rabbit platelets

Production of platelet-activating factor by washed rabbit platelets under stimulation with the ionophore A23187 was investigated utilizing two groups of platelet preparations. The first platelet preparation contained 0.03 +/- 0.02% contaminating white cells, while the second preparation contained 0.48 +/- 0.27% white cells. The latter preparation produced platelet-activating factor, mainly 1-hexadecyl-2-acetyl-sn-glycero-3-phosphocholine, 8.3 +/- 6.3 pmol (mean +/- standard deviation) with a range of 2.6 to 21.4 pmol (n = 9), followed by small quantities of 1-octadecenyl- and 1-octadecyl-2-acetyl-sn-glycero-3-phosphocholine. In contrast, there was no production of 1-alkyl-2-acetyl-sn-glycero-3-phosphocholine by the former platelet preparation having 0.03% leukocytes. These quantitative analyses were carried out by the selected ion monitoring technique and it was concluded that it is necessary to consider the presence of contaminating white cells in studies on the production of platelet-activating factor by platelets.     

Amino acid sequence of polypeptide chain IIB of extracellular hemoglobin from the polychaete Tylorrhynchus heterochaetus

The giant extracellular hemoglobin from the polychaete Tylorrhynchus heterochaetus consists of two types of subunits: a "monomeric" chain (chain I) and a disulfide-bonded trimer of chains IIA, IIB, and IIC. The complete amino acid sequence of chain IIB was determined. This chain has 148 amino acid residues and a molecular weight of 17,236 including a heme group. Of the residues in chain IIB, 74 (50%) and 34 (30%) were found to be identical with those in the corresponding positions in Tylorrhynchus chains IIC and I, respectively (Suzuki, T., Furukohri, T., and Gotoh, T. (1985) J. Biol. Chem. 260, 3145-3154). Marked differences were found between the chains of Tylorrhynchus and Lumbricus in the COOH-terminal regions. Significant differences were predicted between the monomeric chain I and the "trimeric" chains (IIB and IIC) in the hydropathy profiles and alpha-helical contents.     

Intravesical treatment of bladder cancer with recombinant human interferon-β

Summary In order to examine its clinical efficacy, recombinant human interferon- (rIFN-) was instilled intravesically into 51 patients with superficial bladder cancer. Ten patients, who received intermittent intravesical instillation at a dose of (3–36) × 10⁶ U rIFN- on days 1–3 every week, showed no response. Thirty-two patients received intravesical instillation at a dose of (3–36) × 10⁶ U every day for 10–20 days. Eight patients showed partial response, indicating an efficacy rate of 25%. Nine patients received divided doses of 18 × 10⁶ U twice a day every day for 10–20 days. Six patients showed partial response, indicating an efficacy rate of 67%. This value was significantly higher than that obtained by administering divided doses. The response to intravesical instillation therapy with rIFN- varies with treatment protocol. Frequent and longer exposure to rIFN- may induce better regression of superficial bladder cancer. Six incidences of side-effects were found in five cases (9.8%): pollakiuria in one, pain on micturition in two, fever in two, and eruption in one case. All of these side-effects were slight and reversible after drug withdrawal. Laboratory tests showed only a few changes with low severity. Thus, rIFN- is potentially a new drug for instillation therapy of superficial bladder cancer, in view of the absence of adverse effects.     

Utilization of Anhydrous Aluminum Phosphate as a Sole Source of Phosphorous by a Selected Carrot Cell Line

Two variants of carrot (Daucus carota L. cv. MS Yonsun) celllines, which had been selected with Al-phosphate as a sole sourceof phosphorous, were characterized on their mechanisms of phosphate-utilizationfrom Al-phosphate. Both cell lines excreted citrate into themedium. The amount of citrate excretion was highly correlatedwith cell growth in the presence of Al-phosphate. There wasabout a 1 to 1 correlation between solublized-Al and excreted-citratein the medium during cell growth. These results suggest that1) the citrate could chelate with Al, at a 1 to 1 ratio, inAl-phosphate, 2) the citrate-chelated Al remains outside thecells, and 3) solublized phosphate from Al-phosphate is utilizedfor the growth of carrot cells. The characteristics of the selectedcells were very stable, since the rate of citrate-excretionshowed no change after subculturing 25 passages without Al-phosphate. (Received August 7, 1989; Accepted October 19, 1989)     

Expression of NADH-Dependent Glutamate Synthase in Response to the Supply of Nitrogen in Rice Cells in Suspension Culture

The effects of inorganic and organic nitrogen on the levelsof mRNA for NADH-dependent glutamate synthase (GOGAT) and theprotein were examined in rice cells in suspension culture. Asupply of NH⁺₄, NO^-₃, glutamine, or asparagine induced the accumulationof the protein and mRNA, but levels of mRNA for ferredoxin-GOGATwere hardly affected. ¹Present address: P.C. Center Wakuya-cho, Toda-gun, Miyagi,Japan.