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At least 505 records · Page 28Linked to original sources
PubMed1995

A comparison of the leech Theromyzon tessulatum angiotensin I-like molecule with forms of vertebrate angiotensinogens: a hormonal system conserved in the course of evolution.

After five steps of purification including gel permeation, anti-angiotensin I affinity column chromatography followed by reverse-phase HPLC, a peptide immunoreactive to two different antisera (anti-angiotensin II and anti-angiotensin I) was purified to homogeneity from extracts of the leech Theromyzon tessulatum. The first 14 amino acid residues of the purified peptide (DRVYIHPFHLLXWG) established by automated Edman degradation, reveal the existence in leeches of an angiotensin I-like molecule close to human angiotensin I. The sequence of the purified peptide presents 78.5% of homology with the N-terminal part of human angiotensinogen. Moreover, in its sequence, this peptide presents the cleavage sites of vertebrate angiotensin metabolic enzymes, i.e. the renin and the angiotensin-converting enzyme. This finding constitutes the first biochemical characterization of an angiotensin I in Invertebrates. It also reflects the high conservation of angiotensins in the course of evolution, suggesting a fundamental role of this family in fluid homeostasis.

Amino Acid Sequence↗
PubMed1995

A comparison of the N-terminal sequence of the leech Theromyzon tessulatum angiotensin converting-like enzyme with forms of vertebrate angiotensin converting enzymes.

This paper reports the purification of an angiotensing-converting like enzyme (ACE) of ca. 120 kDa from extracts of head membranes of the leech Theromyzon tessulatum. After solubilization with Triton X-114, the ACE-like enzyme contained in the detergent-poor fraction was separated using five steps of purification including gel permeation and anion exchange chromatographies followed by reverse-phase HPLC. The first 23 amino acid residues of the N-terminal part (GLDPELSPGCFSADEAGAQLFAE) of the purified S-pyridylethylated leech ACE established by automated Edman degradation revealed ca. 87% sequence identity with the N-terminal sequence of the guinea pig ACE. This enzyme cleaves the hyppuryl-His-Leu substrate with a specific activity of 5600 nmol hyppurate min-1 mg protein-1. Hydrolysis of this substrate by ACE-like enzyme is inhibited at 80% by 10 microM captopril or 10 microM lisinopril (IC50 of 200 nM and 50 nM, respectively). This enzyme is close in sequence and in activity to single domain vertebrate ACE. This is the first N-terminal sequence of an ACE-like enzyme determined in invertebrates.

Amino Acid Sequence↗
PubMed1996

Extracellular Ca2+ changes during transmitter application in the leech central nervous system.

Changes in extracellular Ca2+ concentration ([Ca2+]e) evoked by transmitters and transmitter agonists, respectively, and by elevation of bath K+ concentration were recorded in isolated segmental ganglia of the leech Hirudo medicinalis using Ca(2+)-selective microelectrodes. A 1-min bath application of kainate (10 microM), glutamate (1 mM), aspartate (1 mM), or carbachol (200 microM) decreased [Ca2+]e by up to 1 mM, whereas the inhibitory transmitters gamma-amino butyric acid (GABA, 100 microM) and serotonin (5-HT, 100 microM) did not change [Ca2+]e. The amplitude of the kainate-induced changes in [Ca2+]e increased with repetitive applications, and changes were blocked by 6-cyano-7-dinitroquinozaline-2,3-dione (CNQX). Elevation of bath K+ concentration from 4 to 40 mM led to a Ni(2+)-sensitive decrease in [Ca2+]e by 0.9 mM. Our results suggest that excitatory transmission in the leech central nervous system might be accompanied by substantial decreases in [Ca2+]e.

Animals↗
PubMed1986

Serine protease inhibitors of North American leeches.

Serine protease inhibitors in extracts from three North American leeches, Nephelopsis obscura, Erpobdella punctata and Hemopis marmorata have been separated by anion exchange chromatography and the activity pattern against human granulocyte elastase and porcine chymotrypsin and trypsin determined. All three leech species contained a major peak with anti-trypsin activity, but Hemopis was unique in that the trypsin inhibitor was equally active against chymotrypsin. Nephelopsis was rich in anti-elastase activity of two types, one which was also active against chymotrypsin, and one which was a specific elastase inhibitor. Erpobdella contained inhibitors against elastase and chymotrypsin but with major activity against the latter.

Animals↗
PubMed1987

The saliva of the medicinal leech Hirudo medicinalis--I. Biochemical characterization of the high molecular weight fraction.

1. A method is described for obtaining dilute Hirudo medicinalis saliva by feeding leeches through a membrane on arginine/saline and squeezing them immediately after from the posterior end forwards. The process can be repeated at intervals. Yields are considerably higher than from salivary gland extracts. 2. Hirudo saliva contains hirudin, eglin, hyaluronidase, collagenase and apyrase. Leech collagenase and apyrase are here reported for the first time. 3. On gel filtration of lyophilized saliva, activity peaks were well defined. Approximate molecular weights were determined. Apyrase appears in two forms with optimum activity around pH 7.5. Collagenase was identified as belonging to the mammalian type.

Adenylate Kinase↗
PubMed1993

Evidence for two isoforms of carbonic anhydrase II in the leech (Hirudo medicinalis) central nervous system.

1. We dissected, homogenized and prepared ganglia and connectives from the central nervous system of medicinal leeches for SDS gel electrophoresis. The isolated proteins were transferred to nitrocellulose and incubated with affinity column-purified antibodies. 2. The immunoblots showed a strong positive reaction of a bovine carbonic anhydrase standard at a molecular weight of 29 kDa, and a distinct double-bond at the same molecular weight in the analyzed material. 3. We demonstrated with rat antibodies that carbonic anhydrase II is detectable in the leech central nervous system as the main isoenzyme. 4. The biochemical knowledge of carbonic anhydrase reported here agrees well with the immunocytochemical locations, thus affirming the validity of specific staining.

Animals↗
PubMed1990

Mechanism of action of triethyltin on identified leech neurons.

The effects of triethyltin (TET) have been examined using intracellular electrophysiological recording techniques from identified neurons of the leech (Hirudo medicinalis) CNS and from salivary glands of the giant Amazon leech (Haementeria ghilianii). TET, at concentrations as low as 10(-5) M, caused a reversible neuronal membrane depolarisation accompanied by an increase in firing frequency of action potentials (which could lead to conduction block at 10(-4) M) and a concomitant decrease in membrane resistance. TET-induced membrane depolarisation still occurred in saline where Na+, K+ and Ca2+ had been replaced by choline. TET decreased the rate of the depolarising and repolarising phases of the action potential. This also occurred in Haementeria salivary gland cells, in which the only inward cation channel is a calcium channel. The calcium channel blocker, manganese, did not block the effects of TET. TET counteracted the effects on the action potential of the potassium channel blocker, tetraethylammonium chloride (TEA). TET-induced neurotoxicity occurred independently of any resultant toxic effects on the myelin sheath. The action of TET is consistent with our view that it causes an increase of intracellular free Ca2+ probably via release from intracellular stores and inhibition of Ca2+ reuptake. A resulting inhibition of the Na+/K+ and Ca2+ pumps may also occur.

Action Potentials↗
PubMed1983

Differential action of tetrodotoxin on identified leech neurons.

1. In leech segmental ganglia, the maximum rate of depolarization of action potentials was found to depend largely on Na in the Retzius (R) cell, the mechanosensory P, N and T cells and an identifiable neuron of unknown function, the X cell. 2. Tetrodotoxin (TTX) 15 100 mumol/l had little or no effect on R and X cells. In contrast, membrane excitation in N, P and T cells was depressed in dose- and use-dependent fashion. 3. The data imply the existence of two kinds of Na channels in normal, fully differentiated leech neurons. Correlation of such differences should lead to a better understanding of how particular neurons perform different functions.

Action Potentials↗
PubMed1984

The ionic mechanisms associated with the excitatory response of kainate, L-glutamate, quisqualate, ibotenate, AMPA and methyltetrahydrofolate on leech Retzius cells.

Intracellular recordings were made from Retzius cells from segmental ganglia of the leech, Hirudo medicinalis. The ionic mechanisms of the following compounds were examined: L-glutamate, ibotenate, quisqualate, AMPA, kainate, methyltetrahydrofolate and carbachol. All these compounds depolarise and excite Retzius cells. In sodium-free Ringer, the responses to L-glutamate, kainate, ibotenate and AMPA were greatly reduced, the response to quisqualate was reduced, the response to methyltetrahydrofolate was normal while the response to carbachol was abolished. In sodium-free high calcium Ringer the responses to L-glutamate, ibotenate and carbachol were absent, the responses to quisqualate and AMPA greatly reduced, the responses to methyltetrahydrofolate and kainate were normal. The methyltetrahydrofolate and kainate responses in sodium-free high calcium Ringer were greatly reduced on addition of cobalt. All the responses are associated with an increase in conductance, the increase being the largest in the case of kainate. It is concluded that the response to L-glutamate, ibotenate and carbachol are dependent on sodium, the responses to quisqualate and AMPA are mainly sodium dependent, possibly with a small calcium component. The kainate response in normal Ringer is largely sodium dependent but in sodium-free Ringer calcium can completely substitute for sodium. The methyltetrahydrofolate response appears to be sodium independent but at least partly calcium dependent. These studies provide further evidence that L-glutamate and ibotenate act on a common receptor on leech Retzius cells while kainate acts on a separate receptor which can activate a calcium ionophore. It is probable that methyltetrahydrofolate acts on a different ionophore system to kainate. N-Methyl-D-aspartate has no agonist activity on any of these receptors.

Action Potentials↗
PubMed1986

Leech Retzius cells and 5-hydroxytryptamine.

A pair of giant Retzius (R) cells in each segmental ganglion of the leech contain 5-hydroxytryptamine (5-HT). They are the only 5-HT-containing neurones in the central nervous system to send branches to the periphery, yet many peripheral tissues (e.g. body wall muscles, heart, reproductive organs, nephridia and gut) possess 5-HT-like immunoreactive nerve fibres. 5-HT and/or R cell stimulation relax basal tension of body wall muscles and reduce their relaxation times following contraction, enhance pharyngeal movements and salivary gland secretion but inhibit muscle movements of the posterior gut regions and of the reproductive tract. It is suggested that R cells are multifunction neurones modulating activity of many tissues so that feeding behaviour of the leech is carried out as efficiently as possible.

Animals↗
PubMed1989

Modulation of swimming activity in the medicinal leech by serotonin and octopamine.

1. The monoamines serotonin (5-HT) and octopamine (OA) enhance the expression of swimming activity in the medicinal leech (Willard, 1981; Belanger and Orchard, 1988). We explored further the effects of these monoamines and related agents on swimming activity observed in isolated leech nerve cords. 2. We confirmed that swimming activity is induced reversibly following exposure of the nerve cord to 5-HT (50 microM); the half-maximal rate of swimming activity develops in about 15 min. Swimming activity returns to control levels about 30 min after drug washout. 3. Swim-induction by 5-HT is blocked by the presence of 10 microM cyproheptadine (a 5-HT antagonist). 4. Although apparently less effective than 5-HT, OA application to nerve cords also induced swimming activity. 5. Depletion of endogenous amines from nerve cords by acute exposure to reserpine (10-150 microM) blocked stimulus-evoked swimming activity within 4 hr. 6. Subsequent application of 5-HT (50 microM) or OA (100 microM) reinstated stimulus-evoked swimming and induced repeated episodes of non-triggered swimming activity. 7. Application of cAMP and cAMP analogs, as well as phosphodiesterase inhibitors (theophylline and IBMX), mimicked the effects of the monoamines, suggesting that 5-HT and OA may activate swimming activity by increasing neuronal cAMP. 8. We obtained episodes of swim-like activity from individual, isolated ganglia exposed to 5-HT or OA. Such episodes were usually brief, with variable cycle period. 9. We conclude that individual nerve cord ganglia contain the complete neuronal circuitry required to generate the rudiments of swimming activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Neuromodulatory effects of acetylcholine and serotonin on the sensitivity of leech mechanoreceptors.

1. Each segmental ganglion of the leech Hirudo medicinalis contains 6 touch (T) cells, 4 pressure (P) cells and 4 nociceptive (N) cells. The receptive terminals of these cells innervate the skin in discrete areas. These cells are known to have extrasynaptic receptors. 2. We tested the effect of transmitter substances present in leech CNS on the sensitivity of T and P cells to mechanical stimuli. Substances tested included octopamine, FMRFamide, proctolin, substance P, glutamate, GABA, acetylcholine and serotonin. 3. Only acetylcholine and serotonin had consistent effects. Serotonin (1 x 10(-3) M) increased the number of action potentials of T cells elicited by a standard stimulus. Serotonin (1 x 10(-4) M) and acetylcholine (1 x 10(-3) M) increased the number and frequency of action potentials in P cells.

Acetylcholine↗
PubMed1995

Neurotoxic action of some antiarrhythmic agents: comparative effects of propafenone, lidocaine and amiodarone on leech Retzius nerve cell.

A series of antiarrhythmic drugs was studied on spontaneous spike activity and depolarizing outward potassium current in leech Retzius nerve cells. Propafenone (0.7 microM/ml) produced a cardiac-like action potential with a rapid depolarization followed by a sustained depolarization or plateau, which is terminated after 250 msec by a rapid repolarization. The effect of lidocaine (0.7 microM/ml) on spontaneous spike activity was less pronounced, and early afterdepolarization has been recorded. Amiodarone at the same and much higher concentrations (3 microM/ml) did not generate either a cardiac-like action potential or an early afterdepolarization. In the voltage clamp experiments, fast and slow calcium-activated outward potassium currents were suppressed with propafenone and lidocaine but not with amiodarone. These results suggest that the antiarrhythmic drugs, propafenone and lidocaine modulate calcium-activated potassium channels in leech Retzius nerve cells.

Action Potentials↗
PubMed2006

Regulation of the mechanosensitive cation channels by ATP and cAMP in leech neurons.

Single-channel recordings were used to study the modulation of stretch-activated channels (SACs) by intracellular adenosine nucleotides in identified leech neurons. These channels exhibited two activity modes, spike-like (SL) and multiconductance (MC), displaying different polymodal activation. In the absence of mechanical stimulation, internal perfusion of excised patches with ATP induced robust and reversible activation of the MC but not of the SL mode. The ATP effect on channel activity was dose-dependent within a range of 1 microM-1 mM and was induced at different values of intracellular pH and Ca2+. The non-hydrolyzable ATP analog AMP-PNP, ATP without Mg2+ or ADP also effectively enhanced MC activity. Adenosine mimicked the effect of its nucleotides. At negative membrane potentials, both ATP and adenosine activated the channel. Moreover, ATP but not adenosine induced a flickering block. Addition of cAMP during maximal ATP activation completely and reversibly inhibited the channel, with activation and deactivation times of minutes. However, cAMP alone only induced a weak and rapid channel activation, without inhibitory effects. The expression of these channels in the growth cones of leech neurons, their permeability to Ca2+ and their sensitivity to intracellular cAMP are consistent with a role in the Ca2+ oscillations associated with cell growth.

Adenosine Triphosphate↗
PubMed2004

L-type Ca2+ channel antagonists block voltage-dependent Ca2+ channels in identified leech neurons.

We investigated the effect of L-type Ca2+ channel antagonists on the Ca2+ influx through voltage-gated Ca2+ channels in leech Retzius, Leydig, AP, AE, P, and N neurons. The efficacy of the antagonists was quantified by monitoring their effect on the increase in the intracellular free Ca2+ concentration ([Ca2+]i; measured by Fura-2) that was induced by depolarizing the cell membrane by raising the extracellular K+ concentration. This K+-induced [Ca2+]i increase was blocked by the phenylalkylamines verapamil, gallopamil, and devapamil, the benzothiazepine diltiazem, as well as by the 1,4-dihydropyridine nifedipine. The blocking effect of the three phenylalkylamines was similar, being most pronounced in P and N neurons and smaller in Leydig, Retzius, AP, and AE neurons. Contrastingly, diltiazem and nifedipine were similarly effective in the neurons investigated, whereby their efficacy was like that of the phenylalkylamines in Retzius, Leydig, AP, and AE neurons. Depending on cell type and blocking agent, the concentrations necessary to suppress the K+-induced [Ca2+]i increase by 50% were estimated to vary between 5 and 190 microM. At high concentrations, the phenylalkylamines and diltiazem by themselves caused a marked [Ca2+]i increase in Leydig, P, and N neurons, which is probably due to activation of the caffeine-sensitive ion channels present in the plasma membrane of these cells. Together with previous observations, the results indicate a distant relationship of the voltage-gated Ca2+ channels present in many if not all leech neurons to vertebrate L-type Ca2+ channels.

Animals↗
PubMed2004

The value of medical leeches in the treatment of class IIC ring avulsion injuries: report of 2 cases.

Ring avulsion injuries pose a serious problem for the hand surgeon. According to the severity of the injury several classifications and their modifications have been proposed. In class IIC ring avulsion injuries arterial circulation is intact but only the venous supply is disrupted. Several therapeutic approaches have been suggested for these types of injuries. We present two class IIC cases that were treated successfully solely with leeches, with excellent results. Although the method is not a substitute for microvascular intervention leeches can be used when the clinical condition of a patient does not permit a lengthy surgery and if microvascular techniques fail or are thought to be pointless.

Adult↗
PubMed2005

Snail peptide expression pattern in the nervous system of the medicinal leech.

Distribution of neurons immunopositive to antibodies against the "command neuron peptides" (CNPs) encoded by the snail Helix Command-Specific 2 (HCS2) gene was investigated in the nervous system of medicinal leech Hirudo. Immunopositive neurons were found in the leech segmental ganglia, brain and tail ganglionic masses, and peripheral ganglia. The CNPs immunopositive fibers were observed in neuropils of all ganglia and in some nerves. The role of CNPs immunopositive cells in animal behavior and the putative functions of the CNPs neuropeptide family are discussed.

Animals↗
PubMed2004

Leech therapy in penile replantation: a case of recurrent penile self-amputation.

Penile amputation is a rare urologic trauma for which immediate surgical replantation is indicated. Microsurgical techniques can reduce skin and graft loss complications; nonetheless, such complications are still highly prevalent. We report a case of self-inflicted penile amputation and describe a nonmicrosurgical technique for replantation. To improve postoperative edema due to venous congestion, we applied medicinal leeches to the penis. The edema quickly resolved, but overlying skin loss occurred, which required superficial debridement. At follow-up the patient had glans re-epithelialization with normal voiding, sensation, and erections. To our knowledge, this is the first reported case of nonmicrosurgical penile replantation with leech therapy.

Adult↗