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At least 1,153 records · Page 64Linked to original sources
PubMed1999

Comparison of precursor structures of the GGNG peptides derived from the earthworm Eisenia foetida and the leech Hirudo nipponia.

Earthworm and leech cDNAs encoding the GGNG peptides, a family of myotropic peptides, were cloned and examined in this study. Both of the predicted precursor proteins are of polyprotein structure and contain several putative peptides distinct from the GGNG peptides. However, the precursors show organizations distinct from each other and no sequence similarity except for the GGNG peptides.

Amino Acid Sequence↗
PubMed2006

Forgotten digital tourniquet: salvage of an ischaemic finger by application of medicinal leeches.

Individual finger tourniquets are appropriate to the management of a wide range of conditions presenting to an accident and emergency department. They are simpler and more comfortable to use than upper arm pneumatic tourniquets and commercially available digital tourniquets are not readily available in the accident and emergency unit. However, if a finger tourniquet is overlooked, ischaemia of the digit results, and gangrene may follow if the problem is not defused early enough, leading to potential disaster. We present one case where a digit was salvaged after 4 days of tourniquet application, using medicinal leeches.

Adolescent↗
PubMed2000

Kinetic and thermodynamic analysis of leech-derived tryptase inhibitor interaction with bovine tryptase and bovine trypsin.

The interaction of leech-derived tryptase inhibitor (LDTI) with bovine liver capsule tryptase (BLCT) and bovine trypsin has been studied using both thermodynamic and kinetic approaches. Several differences were detected: (i) the equilibrium affinity of LDTI for BLCT (Ka = 8.9 x 10(5) M(-1)) is about 600-fold lower than that for bovine trypsin (Ka = 5.1 x 10(8) M(-1)); (ii) LDTI behaves as a purely non-competitive inhibitor of BLCT, while it is a purely competitive inhibitor of bovine trypsin. These functional data are compared with those previously reported for the LDTI binding to human tryptase, where tight inhibition occurs at two of the four active sites of the tetramer (Ka = 7.1 x 10(8) M(-1)). Amino acid sequence alignment of BLCT, human betaII-tryptase and bovine trypsin allows us to infer some possible structural basis for the observed functional differences.

Amino Acid Sequence↗
PubMed2003

Nitridergic platelet pathway activation by hementerin, a metalloprotease from the leech Haementeria depressa.

Hementerin (HT) is an 80 kDa fibrino(geno)lytic metalloprotease, purified from saliva of the leech Haementeria depressa. In the present report, the effect of HT on several functional parameters of human platelets was assessed. HT inhibited platelet aggregation and ATP release induced by different agonists such as ADP, adrenaline, collagen, thrombin, and arachidonic acid. HT did neither modify the expression of platelet glycoproteins (Ib, IIb-IIIa, Ia-IIa, IV) nor intraplatelet fibrinogen levels, whereas it markedly decreased CD62P and CD63 levels after the stimulation with thrombin. HT significantly increased thrombin-induced platelet Ca2+ intracellular levels, cGMP content and nitric oxide synthase (NOS) activity. The effect of HT on platelet aggregation was reversed by two NOS inhibitors, N(omega)-Nitro-L-arginine methyl ester and 2 N(G)-Nitro-L-arginine. In summary, these results indicate that HT is an effective inhibitor of human platelet aggregation, presumably through activation of the platelet's nitridergic pathway.

Adenosine Triphosphate↗
PubMed1977

Isolation and characterisation of a low molecular weight inhibitor (of chymotrypsin and human granulocytic elastase and cathepsin G) from leeches.

Two protein proteinase inhibitors were isolated and purified from the leech Hirudo medicinalis by means of gel filtration and ion-exchange chromatography. They inhibit chymotrypsin, subtilisin and the granulocytic neutral proteases elastase and cathepsin G. They proved to be homogeneous in polyacrylamide and dodecylsulfate gel electrophoresis and by end group analysis; only threonine was found as N-terminal amino acid residue using the dansylation technique. These inhibitors, which we call eglins, are stable in neutral and weakly acid (pH 3) solutions and resist non-specific proteolysis. From the amino acid compositions, a molecular weight of 6 600 - 6 800 is calculated for both inhibitory proteins, which is in good agreement with a value of about 6000 estimated by dodecylsulfate electrophoresis. The eglins contain an unusually large amount of hydrophobic amino acid residues but no methionine, isoleucine or--a rarity--cysteine residues or disulfide bridges. To our knowledge, the eglins are the first examples of proteinase inhibitors of the protein type which are not stabilized by disulfide bridges.

Amino Acids↗
PubMed1994

Recombinant leech-derived tryptase inhibitor: construction, production, protein chemical characterization and inhibition of HIV-1 replication.

A synthetic gene coding for leech-derived tryptase inhibitor, form C (LDTI-C), was designed, cloned and expressed. The gene assembled via 6 oligonucleotides contains linker sequences, stop codons and internal restriction recognition sites for cloning, expression and cassette mutagenesis. Periplasmatic expression products could not be detected in Escherichia coli (E. coli), but strong expression was found using Saccharomyces cerevisiae (S. cerevisiae) ( > 10 mg/l culture broth) if a variant of pVT102U/alpha was used as vector. The secreted material was isolated after cross-flow filtration and purified by cation exchange chromatography. The recombinant material proved to be pure and homogeneous by electrophoretic and chromatographic analyses. Amino acid sequencing and molecular mass determination (4737.6 +/- 0.77 Da) by electrospray ionization mass spectrometry confirmed that rLDTI-C was processed correctly and that it is indistinguishable from LDTI-C. The far UV-CD (circular dichroism) spectrum of the recombinant inhibitor is typical for a small folded protein. rLDTI-C is inhibitorily fully active, its complexes with bovine trypsin and human mast cell tryptase display equilibrium dissociation constants which are nearly identical to those with the natural inhibitor. Remarkably, the inhibitor blocked replication of HIV-1 in HUT-78 cells at a concentration of 20 microM.

Amino Acid Sequence↗
PubMed2006

A 3-synapse positive feedback loop regulates the excitability of an interneuron critical for sensitization in the leech.

Sensitization of reflexive shortening in the leech has been linked to serotonin (5-HT)-induced changes in the excitability of a single interneuron, the S cell. This neuron is necessary for sensitization and complete dishabituation of reflexive shortening, during which it contributes to the sensory-motor reflex. The S cell does not contain 5-HT, which is released primarily from the Retzius (R) cells, whose firing enhances S-cell excitability. Here, we show that the S cell excites the R cells, mainly via a fast disynaptic pathway in which the first synapse is the electrical junction between the S cell and the coupling interneurons, and the second synapse is a glutamatergic synapse of the coupling interneurons onto the R cells. The S cell-triggered excitatory postsynaptic potential in the R cell diminishes and nearly disappears in elevated concentrations of divalent cations because the coupling interneurons become inexcitable under these conditions. Serotonin released from the R cells feeds back on the S cell and increases its excitability by activating a 5-HT7-like receptor; 5-methoxytryptamine (5-MeOT; 10 microM) mimics the effects of 5-HT on S cell excitability, and effects of both 5-HT and 5-MeOT are blocked by pimozide (10 microM) and SB-269970 [(R)-3-(2-(2-(4-methylpiperidin-1-yl)-ethyl)pyrrolidine-1-sulfonyl)phenol] (5 microM). This feedback loop may be critical for the full expression of sensitization of reflexive shortening.

Animals↗
PubMed2000

Marine leech, Stibarobdella macrothela (Schmarda, 1861) (Hirudinea, piscicolidae), parasitic on the whaler shark, Carcharhinus Brachyurus (Günther, 1870) (Chondrichthyes, Carcharhinidae), in Southern Brazilian waters.

The presence of the sea leech, Stibarobdella macrothela (Schmarda, 1861) (Hirudinea, Piscicolidae), is marked in the south coast of Brazil, based on the single specimen with 67 mm (CT), collected in the intergill ventral region of a whaler shark, Carcharhinus brachyurus (Günther, 1870) (Chondrichtyes, Carcharhinidae), adult male with about 2 m (CT), being treated of the first registrations of S. macrothela in the Southwest Atlantic and the parasitic association with C. brachyurus.

Animals↗
PubMed2004

The marine leech Stibarobdella loricata (Harding, 1924) (Hirudinea, Piscicolidae), parasitic on the angel shark Squatina spp. and sandtiger shark Carcharias taurus Rafinesque, 1810 (Chondrichthyes: Squatinidae, Carchariidae) in Southern Brazilian waters.

The presence of the marine leech, Stibarobdella loricata (Harding, 1924) (Hirudinea, Piscicolidae), is reported on the southern coast of Brazil, based on seven lots with 47 specimens, between 71 and 182 mm in total length, collected on the dorsal region of angel sharks, Squatina argentina (Marini, 1930); S. guggenheim Marini, 1936; S. punctata Marini, 1936 (Chondrichthyes, Squatinidae); and on the head of a sandtiger shark, Carcharias taurus Rafinesque, 1810 (Chondrichthyes, Carchariidae). This is the first record of S. loricata in the western Atlantic and of its parasitic association with S. argentina, S. guggenheim, S. punctata, and C. taurus.

Animals↗
PubMed2001

Transmission of Haemogregarina balli from painted turtles to snapping turtles through the leech Placobdella ornata.

Six leeches (Placobdella ornata) were allowed to feed on a painted turtle (Chrysemys picta marginata) infected with Haemogregarina balli and subjected to a period of diapause before being allowed to feed on 2 laboratory-reared snapping turtles (Chelydra serpentina). Weekly examination of thin blood films revealed infections of the turtles at 130 days postfeeding. These observations provide support for broad host specificity of hemogregarine parasites of chelonians.

Animals↗
PubMed2006

A redescription of the fish leech Pterobdella amara (= Rhopalobdella japonica) (Hirudinida: Piscicolidae) based on specimens from the type locality in India and from Australia.

Pterobdella amara is redescribed from specimens from the type locality in India, and from the type host in Queensland, Australia. A neotype is designated from the type locality. The presence of conspicuous finlike bodies along the lateral margins of P. amara was greatly exaggerated in the original description. The trachelosome and anterior portion of the urosome are wide and flat, but there are no finlike bodies present. The urosome tapers abruptly posterior to the flattened portion, becomes cylindrical, and remains of constant width to the caudal sucker. The oral sucker is small and the caudal sucker is terminal. The body is smooth and lacks pigmentation, except for 1 pair of eyes on the oral sucker. Important internal characters are 2 pairs of mycetomes, 5 pairs of testisacs, confluent gonopores, extensive accessory gland cells on the male atrium and ejaculatory ducts, a spacious coelom consisting of dorsal and ventral sinuses with expansive connections between each at urosome ganglia, and interganglionic expansions of the dorsal sinus. Rhopalobdella japonica from stingrays in Japan is synonymized with P. amara and becomes a subjective junior synonym. This leech is a parasite in the oral cavity of the stingrays Pastinachus sephen and Himantura uarnak in India and Australia, and Dasyatis akajei in Japan.

Animals↗
PubMed2002

Trypsin and chymotrypsin inhibitors in insects and gut leeches.

The constant increase of life expectancy is associated with major ageing of developed populations. This indicates that the new century will have one of most epidemic progressions of cardiovascular, cancer and inflammatory diseases. The high challenge for medical research is to compress such morbidity. In these conditions, invertebrates have demonstrated to be truly useful models in drug discovery for such ageing diseases. The last decade, drug discovery in leeches has opened the gate of new molecules to treat emphysema, coagulation, inflammation, dermitis and cancer. Also other invertebrates such as insects, which evolved from the annelids, harvest potential interesting molecules, such as serine protease inhibitors that can be exploited by the medical industry.

Animals↗
PubMed2003

Leeches: immune response, angiogenesis and biomedical applications.

The innate immune response is the first line of defence strategies in invertebrates against attack of infectious agents. A detailed analysis of the immune mechanisms involved in annelids has been performed in oligochaets, but few data are available in polichaets and hirudineans. The aim of this review is to describe the responses of leeches to different kinds of stimuli (infections following non-self agent attacks, surgical lesions, grafts). Furthermore, the use of this invertebrate as a novel experimental model to be used to screen drugs and genes, which are responsible for positive and negative modulation of angiogenesis, is discussed.

Animals↗
PubMed1990

Epidemic oral ulceration in largemouth bass (Micropterus salmoides) associated with the leech Myzobdella lugubris.

An epidemic of severe ulcerations of the tongue and buccal cavity was documented in subadult and adult largemouth bass (Micropterus salmoides) from Currituck Sound, North Carolina (USA). Other external clinical signs were not present. Between November 1986 and May 1987, reports from fishermen indicated that as many as 90% of large (greater than 300 mm total length) bass were affected. Older fish were the most commonly involved. The leech, Myzobdella lugubris (= Illinobdella moorei), was consistently present on or near the lesions. Lesions were heavily infected with several different bacteria that were apparently secondary invaders. Stressful (high) salinity or an interruption in the normal migratory cycle of the parasite are suggested as possible causes for this condition in these bass.

Animals↗
PubMed2002

A functional asymmetry in the Leech Heartbeat Timing Network is revealed by driving the network across various cycle periods.

We tested predictions of a computational model (Hill et al., 2002) of the leech heartbeat timing network. The timing network consists of two segmental oscillators located in the third (G3) and fourth (G4) segmental ganglia. Each oscillator consists of two reciprocally inhibitory oscillator interneurons along with the coordinating interneuron fibers that link them. In the model, the network was driven to cycle periods around the normal period of the network by repeatedly stimulating one of the paired oscillator interneurons in G3 or G4. Here we replicate these experiments in the biological system. The model predicts that the G3 and G4 oscillators can entrain the timing network to periods faster but not slower than the inherent period of the nondriven ("follower") oscillator and that they can do so symmetrically. The biological system can be driven to periods both faster (such that the driven oscillator leads in phase) and slower (such that the driven oscillator lags in phase) than the inherent period of the timing network. Although both oscillators can entrain the network, the G4 oscillator does so over a narrower range of periods. Two differences between the assumptions of the model and the properties of the biological network, spike frequency adaptation in coordinating interneurons and asymmetry in the connections from the oscillator interneurons to the coordinating interneurons, may account for these discrepancies. Individual coordinating interneurons were also able to entrain the oscillators but with little effect of the phase relationship between the oscillators, suggesting that phase relations are determined by properties inherent to the oscillator interneurons.

Action Potentials↗
PubMed1999

Dendritic calcium transients in the leech giant glial cell in situ.

Glial cells have been shown to respond to neuronal activity with changes in the membrane potential and the intracellular Ca2+ concentration. In order to get closer to glial structures associated with neuronal synapses, we have now looked at Ca2+ signalling in the glial processes ("glial dendrites") in response to neurotransmitters and neuronal activity. Single giant glial cells in situ of isolated ganglia of the leech Hirudo medicinalis were filled iontophoretically with the Ca(2+)-sensitive dyes Oregon green 488 BAPTA-1 or Fluo-3. Relative Ca(2+)-dependent fluorescence changes in response to bath and focal application of the ionotropic glutamate receptor agonist kainate (50 microM) and of 5-hydroxytryptamine (5-HT, 100 microM) were recorded in glial dendrites, using confocal laser scanning microscopy. The amplitudes of the [Ca2+]i transients in the dendritic processes were 2-4 times larger than those recorded in the cell body. Electrical stimulation of a nerve root (20 Hz for 15 s) elicited [Ca2+]i transients in glial dendrites (n = 32) that were reduced by the ionotropic glutamate receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX; n = 14). The results demonstrate that neuronal activity can evoke [Ca2+]i transients not only in glial cell bodies but also in glial dendrites, where these transients display regional variation. This may reflect local release of neurotransmitters like glutamate and 5-hydroxytryptamine and/or regional differences in the density of glial receptors.

6-Cyano-7-nitroquinoxaline-2,3-dione↗
PubMed1999

[The hydrolysis of Glu(gamma-epsilon)Lys-amide bonds in D-dimer fragment of fibrin by destabilase from medicinal leech].

A study was made of the dependence of the hydrolysis rate of isopeptide bonds in the D-dimer, the product of limited proteolysis of the stabilized fibrin by plasmin, on the high-molecular substrate concentration catalyzed by destabilase from the medicinal leech. The formation of the reaction product was electrophoretically measured by the increase in the quantity of D-monomer. This dependence was shown to be nonlinear.

Animals↗
PubMedDate not supplied

[Role of Ca2+ in regulating the serotonin-dependent synapse between P and R-cells of leech segmented ganglion].

Changes in the membrane-associated Ca2+ concentration and viscosity of the plasmatic membrane of P- and R-cells segmented ganglia of medicinal leech upon a variation of extracellular serotonin concentration were investigated. It is shown that the transmission of rhythmic excitation from P- to R-cells is due to the formation of the serotonin-dependent synapse and affects the distribution of the membrane-associated Ca2+ and intracellular processes controlling the viscosity of the membrane.

Animals↗