Hideyuki Nakagawa

Mercury levels in human hair and sex factors.

Abstract Evidence has been presented: (1) that the geometric mean is essential to the statistical analysis of the result of the amount of Hg in hair, and (2) that the individual Hg level in hair must be evaluated by the standard deviation of logarithmic values. The Hg level in hair obtained from 1324 inhabitants on Shikoku island showed logarithmic-normal distribution curves, with higher values in males than in females. To verify such a sexual difference, hair samples were obtained from male and female children (N = 346), teenagers (N = 300), and adults (N = 354) living in an agricultural area of Tokushima Prefecture on the island. As the result, males were found to have more Hg than females in sexually mature teenagers and adults (P

Recent Studies on the Pathological Effects of Purified Sea Urchin Toxins

Sea urchins are the popular name for marine invertebrates that belong to the phylum Echinodermata. Approximately 200 species of sea urchin are found on the coast of Japan, while several species of echinoids are dangerous to humans. Envenomations are caused by stings from either pedicellariae or spines. In our search for bioactive compounds we have been investigating mitogenicity and/or cytotoxicity from the venoms of the four sea urchins: Toxopneustes pileolus, Tripneustes gratilla, Diadema setosum, and Asthenosoma species. The toxopneustid sea urchins have well‐developed globiferous pedicellariae with bioactive substances. The hollow primary spines of diadematid sea urchins are suggested to contain bioactive substances. Two D‐galactose‐binding lectins (SUL‐I and SUL‐II ) and a heparin‐binding lectin (TGL‐I) were purified from the globiferous pedicellariae of T. pileolus and T. gratilla. Furthermore, a novel hemolytic lectin with a molecular mass of 29 kDa was isolated from the coelomic fluid of T. gratilla. More recently, we found that a mannose‐containing glycoprotein, Contractin A (18 kDa) is also a novel lectin that caused smooth muscle contraction and relaxation. SUL‐I and Contractin A induced mitogenic stimulation on murine splenocytes, but SUL‐II and TGL‐I did not. SUL‐I promoted chemotaxis of guinea‐pig macrophages and human morphonuclear leukocytes. In murine myeloid leukemic cells (M1 cells) SUL‐I showed not only cytotoxic effect, but also differentiating ability. In addition, SUL‐I partially induced apoptosis to M1 cells. SUL‐I did not show a sequence homology to SUL‐II. However, SUL‐I is related to fisg egg lectins. On the other hand, SUL‐II showed a sequence homology to Contractin A and UT841 from T. pileolus, which may be a phopholipase A2‐like substance. Our data suggest an extracellular function for SUL‐I and Contractin A that may have wide‐ranging effects, and suggest that sea urchin venoms may be regarded as useful bioactive substances.

PURIFICATION AND CHARACTERIZATION OF CONTRACTIN A FROM THE PEDICELLARIAL VENOM OF SEA URCHIN, TOXOPNEUSTES PILEOLUS

A component that causes contraction of the isolated guinea pig tracheal smooth muscle was isolated in homogeneous form from the venom of the pedicellaria of the sea urchin, Toxopneustes pileolus. It is named Contractin A. Contractin A has 18,000 Da with a total residue of 138 amino acids. The molecular weight is about 17,700. The N-terminal amino acid is serine. The partial amino acid sequence was determined up to 37 residues. Direct comparison of sea urchin Contractin A does not show any similarity in amino acid sequence to toxins isolated from other marine toxin producers such as sea snakes, sea anemones, or marine worms. Contractin A caused contraction of the tracheal smooth muscle in a dose-dependent manner. Furthermore, Contractin A relaxed the contraction induced by histamine. The contraction and relaxation activity of Contractin A on the tracheal smooth muscle is reduced by a cyclooxygenase inhibitor such as indomethacin. The contraction induced by Contractin A is also inhibited by a phospholipase C inhibitor but not by a phospholipase A2 inhibitor. These results suggest that in the isolated guinea pig tracheal smooth muscle, the response to Contractin A may be effected through activated phospholipase C.

Isolation of a novel lectin from the globiferous pedicellariae of the sea urchin Toxopneustes pileolus.

Sea urchin lectin-I (SUL-I), a 32 kDa lectin was purified from the large globiferous pedicellariae of the sea urchin, Toxopneustes pileolus by using gel permeation chromatography, ion-exchange chromatography and reverse-phase HPLC. SDS-PAGE showed that SUL-I is a monomeric protein with a molecular mass of 32 kDa. Amino acid analysis indicates SUL-I to contain 294 residues. SUL-I was shown to have chemotactic properties for guinea-pig neutrophils at concentrations of 0.625 microgram/ml. These data suggest that a 32 kDa lectin from T. pileolus may be related to defensive role.

Mast cell activation by pedicellarial toxin of sea urchin, Toxopneustes pileolus

Pedicellarial toxin, partially purified from the sea urchin Toxopneustes pileolus, dose‐dependently and time‐dependently caused histamine release from rat peritoneal mast cells. Pedicellarial toxin induced a rapid initial rise in [Ca2+]i within several seconds which was followed by a further slower increase of [Ca2+] (second rise). The toxin induced a dose‐dependent formation of inositol 1,4,5‐triphosphate (IP3) as well as the histamine release in mast cells. Furthermore, the toxin stimulated phosphoinositide‐specific phospholipase C (PI‐PLC) activity in mast cell membranes. 2‐Nitro‐4‐carboxyphenyl‐N,N. ‐diphenylcarbamate (NCDC), a PLC inhibitor, inhibited the activation of PI‐PCL induced by pedicellarial toxin. Cholera toxin inhibited pedicellarial toxin‐induced histamine release, whereas pretreatment of pertussis toxin failed to inhibit it. These results suggest that pedicellarial toxin from T. pileolus activates PI‐PCL and the stimulation of PI turnover may lead to the release of IP3 into the cytoplasm, resulting in histamine release from rat mast cells.

Action of an extract from the sea urchin Toxopneustes pileolus on isolated smooth muscle

Abstract The pedicellaria of some species of sea urchins contain toxic substances, which are capable of causing injury. In particular, the pedicellaria venoms of the sea urchin, Tripneustes gratilla and Toxopneustes pileolus, exert a variety of pharmacological actions Fujiwara , 1935; Endean , 1961; Mendes et al., 1963; Feigen et al., 1966; Alender , 1967). Recently, Kimura et al. (1975) found toxic substances in pedicellaria of Toxopneustes pileolus and reported that these substances caused a contraction of the isolated smooth muscle. In the present experiments, a pharmacological characterization of the contractile response of an extract from T. pileolus on the longitudinal muscle of the isolated guinea pig ileum was investigated.

Effect of NCDC, a protease inhibitor, on histamine release from rat peritoneal mast cells induced by anti-IgE

NCDC dose-dependently inhibited histamine release from rat peritoneal mast cells induced by anti-IgE. Moreover, NCDC inhibited Ca(2+)-mobilization from intracellular Ca(2+)-stores as well as histamine release in mast cells activated by anti IgE, the effect on both of these phenomena being closely correlated. Anti-IgE induced a rapid increase in IP3 production from phosphoinositides in mast cells, with its production in 15 sec, followed to baseline levels within 1 min. Anti-IgE stimulated PLC activity on mast cells membrane preparation. NCDC dose-dependently inhibited the generation of IP3. These results suggest that the inhibitory effect of NCDC on the release of histamine induced by anti-IgE is due to, in part at least, the inhibition of PI-specific PLC and that the inhibitory effects of NCDC are involved in intracellular calcium store.

Effect of age on the formation of cyclic nucleotides in guinea-pig tracheal smooth muscle in response to pharmacological agents.

The effects of isoproterenol, carbachol and other drugs on the cyclic AMP and cyclic GMP levels in tracheal smooth muscles of guinea-pigs of four different ages were investigated. Isoproterenol increased the cyclic AMP level several-fold in tracheal muscles from newborn (1 week) and young (4-7 weeks) guinea-pigs, but it caused less increase in the level in muscles from middle-aged (12 weeks) and old (20-24 weeks) guinea-pigs, although the basal cyclic AMP level at these ages was not significantly lower. The effects of prostaglandin E1 and cholera toxin in increasing the cyclic AMP level were also markedly less in muscle preparations from old guinea-pigs than in those from young ones. The increase in cyclic AMP levels caused by forskolin, an activator of adenylate cyclase did not decrease with age. Carbachol caused a 3- to 4-fold increase in the cyclic GMP level in muscle preparations from newborn and young guinea-pigs and more increase in the cyclic GMP level in preparations from middle-aged and old guinea-pigs. The increases in cyclic GMP level induced by high K+, histamine and sodium nitroprusside also increased with the age of the animals. These results suggest that the changes in the formation of cyclic AMP and cyclic GMP induced by various agents are due to changes at the post-receptor level.

Histamine release from rat mast cells induced by an extract from the sea urchin Toxopneustes pileolus

The extract caused a dose-dependent release of histamine from rat peritoneal mast cells which was slower in onset than that of compound 48/80. It is also suggested that the extract-induced histamine release is dependent on aerobic glycolysis.

Immunomodulatory activity of a pedicellarial venom lectin from the toxopneustid sea urchin, Toxopneustes pileolus

A novel lectin from the large globiferous pedicellariae of the sea urchin, Toxopneustes pileolus, was isolated by a combination of gel chromatography and affinity chromatography techniques. The 32 kDa lectin appeared to have sequence homology to SUL-I, a D-galactose-specific lectin (). This lectin is named SUL-IA. The N-terminal 7 amino acid sequence of SUL-IA was shown to be AVGRSCE. SUL-IA induced mitogenic stimulation on murine splenocytes and T-lymphocytes. SUL-IA also induced chemotaxis for guinea-pig neutrophils and macrophages. In addition, SUL-IA produced IFN-γ in a higher dose range, but not IL-4. These results suggest that SUL-IA may be a biologically functional lectin, which is one of the multiple lectins from the pedicellarial venom of T. pileolus.