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At least 1,513 records · Page 84Linked to original sources
PubMed1989

Proton-induced chloride current and voltage-activated Na+ and Ca2+ currents in embryonic neurons from the medicinal leech (Hirudo medicinalis).

Voltage-activated ionic currents and currents induced by step changes in proton concentration (pH 7.9-6.7) were studied in early embryonic neurons from Hirudo medicinalis. Ganglia were dissociated at embryonic day (E) 8-15, and the largest neurons were investigated using whole-cell patch clamp recording. All cells studied displayed voltage-activated Na+ and Ca2+ currents. Step changes in pH induced sustained currents which reversed at the equilibrium potential for Cl- and were blocked by substituting Cl- with acetate or sulfate. These currents thus differ in their ion selectivity from proton-induced currents in vertebrate neurons which are carried by Na+.

Animals↗
PubMed1991

Guided outgrowth of leech neurons in culture.

Sensory neurons of Hirudo medicinalis were cultivated on patterns of extracellular matrix (ECM) protein which were prepared by UV irradiation using copper grid masks. The relation of the patterns and of the outgrowth of neurites was observed by scanning electronmicroscopy after gold decoration. The neurites were guided by narrow (10 microM) lanes of ECM protein. Branching of neurites was induced by branched lanes. Bent neurites were pulled off bent lanes at some distance behind the growth cone such that their length was reduced. Regularly spaced sites of adhesion became visible which remained connected to the neurites by extended filaments.

Animals↗
PubMed1992

Proteinases of the medicinal leech, Hirudo medicinalis: purification and partial characterization of three enzymes from the digestive tract.

1. Three different proteinases were isolated from intestinal extracts of Hirudo. 2. The action on synthetic substrates and the effect of various inhibitors indicate that one is a trypsin-like enzyme whereas the other two are chymotryptic. 3. This was confirmed by analysing the degradation of the insulin B-chain. 4. The relative molecular masses of all enzymes are approximately 35,000 and the isoelectric points 9.03, 9.12 and 9.41, respectively. 5. The specific activities assayed with SAPPNA are very high in comparison with proteinases of other animals.

Amino Acid Sequence↗
PubMed1982

The excitatory actions of a series of piperidine dicarboxylates on central neurons of the rat, snail, leech and horseshoe crab and on crab neuromuscular junction.

1. Intracellular recordings were made from Helix, Hirudo and Limulus central neurons and from Eupagurus leg muscle and extracellular recordings from rat lateral geniculate neurons. The actions of 2,3-, 2,4-, 2,5- and 2,6-piperidine dicarboxylates were tested on those preparations for both direct effects and interactions with the response to L-glutamate. 2. All four piperidine analogues were devoid of either reproducible direct or indirect effects on Helix and Limulus neurons save that the 2,5-analogue did mimic the action of L-glutamate on Limulus neurons which were inhibited by glutamate. 3. On Hirudo and rat neurons and on Eupagurus muscle, all four piperidines mimicked the action of L-glutamate, all were weak agonists on rat neurones while on Hirudo neurons the 2,5-analogue was the most potent but on Eupagurus muscle, the 2,3- and 2,6-analogues were the most potent. 4. All four piperidines potentiated the action of L-glutamate on rat and Hirudo neurons and on Eupagurus leg muscle and of muscle ejps. 5. The piperidine analogues indicate that there are differences between the glutamate receptors used in the present study and provide some supportive evidence that the preferred conformation for glutamate on crab leg muscle is partially folded while for Hirudo neurons it is more extended.

Animals↗
PubMed1993

Effect of serotonin on protein phosphorylation in the central nervous system of the leech Hirudo medicinalis.

1. Phosphoproteins of different regions of the Hirudo medicinalis central nervous system have been analysed by means of two-dimensional electrophoresis. 2. Serotonin, 8-Br-cAMP and phorbol 12,13-dibutyrate stimulate phosphorylation of a number of proteins whose isoelectric points and molecular weights are presented. 3. A group of proteins of 78 kDa and pI = 6-6.5, whose level of phosphorylation increases in the presence of serotonin, 8-Br-cAMP and phorbol ester, is observed only in segmental but not in cephalic or caudal ganglia. 4. The putative roles of these phosphoproteins are discussed.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed2004

Evaluation of phage display system and leech-derived tryptase inhibitor as a tool for understanding the serine proteinase specificities.

A small combinatorial library of LDTI mutants (5.2 x 10(4)) restricted to the P1-P4' positions of the reactive site was displayed on the pCANTAB 5E phagemid, and LDTI fusion phages were produced and selected for potent neutrophil elastase and plasmin inhibitors. Strong fusion phage binders were analyzed by ELISA on enzyme-coated microtiter plates and the positive phages had their DNA sequenced. The LDTI variants: 29E (K8A, I9A, L10F, and K11F) and 19E (K8A, K11Q, and P12Y) for elastase and 2Pl (K11W and P12N), 8Pl (I9V, K11W, and P12E), and 10Pl (I9T, K11L, and P12L) for plasmin were produced with a Saccharomyces cerevisiae expression system. New strong elastase and plasmin inhibitors were 29E and 2Pl, respectively. LDTI-29E was a potent and specific neutrophil elastase inhibitor K(i) =0.5 nM), affecting no other tested enzymes. LDTI-2Pl was the strongest plasmin inhibitor ( K(i) =1.7nM) in the LDTI mutant library. This approach allowed selection of new specific serine proteinase inhibitors for neutrophil elastase and plasmin (a thrombin inhibitor variant was previously described), from a unique template molecule, LDTI, a Kazal type one domain inhibitor, by only 2-4 amino acid replacements. Our data validate this small LDTI combinatorial library as a tool to generate specific serine proteinase inhibitors suitable for drug design and enzyme-inhibitor interaction studies.

Animals↗
PubMed2004

Crystallization and preliminary X-ray crystallographic study of the leech protease inhibitor guamerin and its complex with bovine pancreatic chymotrypsin.

Guamerin, a small peptide inhibitor of the serine protease from Hirudo nipponia, was expressed in yeast and crystallized using the vapor diffusion method, with MPD as precipitant. The crystal was found to belong to the monoclinic P2(1) space group with unit cell parameters a=136.06, b=206.59, c=227.39 A, beta=105.03 degrees. The guamerin/bovine pancreatic chymotrypsin complex was also crystallized using PEG 8K as precipitant. The space group was identified as P2(1)2(1)2(1) with unit cell parameters of a=44.01, b=44.30, c=122.47 A. The diffraction data of the complex were collected up to a resolution of 2.4 A using a synchrotron-radiation source under cryogenic condition.

Animals↗
PubMed2003

Leeches.

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Animals↗