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PubMed1990

Intrinsic and extrinsic factors influencing properties and growth patterns of identified leech neurons in culture.

An analysis has been made of intrinsic mechanisms influencing growth patterns of 2 identified leech interneurons in tissue culture. These small cells (known as DL and VL) display unusual arborizations in the ganglion. The distinctive branching patterns resemble the letter "T" for VL and the letter "Y" for DL. DL and VL cells contain serotonin and can be identified in situ with Neutral red. 1. DL and VL cells were isolated and cultured on 2 homogeneous substrates, concanavalin A (Con A) and leech extracellular matrix extract (ECM). Individual DL and VL cells in culture retained their ability to fire in spontaneous, rhythmical bursts. The synaptic connections formed in culture were specific and differed from those made by other serotonergic neurons. 2. On both Con A and ECM the neurons sprouted to reproduce their characteristic patterns. Every DL or VL cell that grew processes on ECM developed the appropriate Y- or T-shaped pattern. On Con A, most but not all of the cells showed specific Y or T patterns. The probability of sprouting was higher on Con A than on ECM. 3. Disruption of microtubular assemblies in freshly isolated DL and VL cells by treatment with nocodazole did not affect the later outgrowth of specific patterns in culture. 4. These results provide evidence that adult DL and VL leech neurons retain intrinsic information for determining a variety of their properties in culture: In particular, they reproduce type-specific neuritic patterns in the absence of extrinsic guidance cues. Moreover, the intrinsic pattern determining mechanism is not lost after the destruction of microtubular arrays within the cytoskeleton.

Animals↗
PubMed1990

Decorsin. A potent glycoprotein IIb-IIIa antagonist and platelet aggregation inhibitor from the leech Macrobdella decora.

The discovery, purification, and characterization of decorsin, a protein isolated from the North American leech Macrobdella decora, are described. Decorsin acts as an antagonist of platelet glycoprotein IIb-IIIa (GPIIb-IIIa), and is a potent inhibitor of platelet aggregation. The protein was purified to apparent homogeneity from crude whole leech extracts by treatment with trifluoroacetic acid followed by GPIIb-IIIa affinity chromatography and C18 reverse-phase high performance liquid chromatography. Decorsin was also isolated from a solution of leech ingestate by treatment with trifluoroacetic acid followed by C18 reverse-phase high performance liquid chromatography. The primary sequence of decorsin indicates that the protein is 39 amino acids long and contains 6 cysteine and 6 proline residues, as well as the sequence Arg-Gly-Asp, (RGD), a proposed recognition site of many adhesion proteins. A molecular mass of 4379 was obtained by fast atom bombardment mass spectrometry and is consistent with the mass calculated from the observed sequence. Evidence for an N-3 isoform, lacking the first 3 amino-terminal residues is also presented. Both decorsin and the N-3 isoform inhibit GP IIb-IIIa binding to immobilized fibrinogen with an IC50 of approximately 1.5 nM. Human platelet aggregation induced by ADP is inhibited by decorsin with an IC50 of approximately 500 nM; complete inhibition was observed at less than or equal to 1 microM. Based on overall sequence homology, decorsin does not belong to the family of GPIIb-IIIa protein antagonists that is found in snake venoms (Dennis, M. S., Henzel, W. J., Pitti, R. M., Lipari, M. T., Napier, M. A., Deisher, T. A., Bunting, S., and Lazarus, R. A. (1990) Proc. Natl. Acad. Sci. U.S.A. 87, 2471-2475); however the carboxyl-terminal RGD-containing region from residues 27 to 38 of decorsin is approximately 60% homologous with the corresponding region of the snake venom proteins, suggesting that high affinity binding of these proteins to GPIIb-IIIa is defined by this epitope.

Amino Acid Sequence↗
PubMed1986

Differential sensitivity of tetrodotoxin of nociceptive neurons in 4 species of leeches.

We have recently shown that the nociceptive neurons (N cells) in the leech can be segregated into a medial type (Nmed) and a lateral type (Nlat) according to their physiological and pharmacological properties. We now report that the Na-dependent action potential (AP) of the 2 cell types in Macrobdella have differential sensitivities to tetrodotoxin and that the APs of the N-cell homologs from different leech species also vary considerably in their response to TTX. The normal AP of the N cells in the 4 leech species was exclusively Na-dependent; its overshoot varied logarithmically with [Na]0, was unaffected by the presence of Mn and absence of Ca, and could not be elicited in Na-free Ringer's solutions. The decrease in the maximal rate of depolarization (Vmax) of the Na-dependent AP of the Nmed cell in Macrobdella produced by TTX followed a reverse Langmuir curve for bimolecular reaction with an ED50 of 9 microM. Almost complete blockage was obtained at 50 microM. In contrast, TTX inhibition of Vmax in the Nlat cell reached saturation at a level of only 55% reduction in Vmax even at doses in excess of 200 microM TTX. The simplest interpretation of these data is that there are 2 types of Na channels in the Nlat cell. This is further supported by the fact that the dose-response data could be well fitted by a Langmuir curve, assuming that the Nlat cell possesses 2 populations of Na conductances--one insensitive to TTX and one (like the Nmed cell) with an ED50 to TTX of 9 microM, the 2 populations being present in a 0.45:0.55 ratio, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed1988

Thrombolytic agents of the preparation from the medicinal leeches.

The thrombolytic effect of an extract from medicinal leeches orally administered to rats was shown. This effect depends on the number of administrations and on the concentration of extract. It is due to the leech prostaglandins and enzyme destabilase. After the extraction of prostaglandins by ethylacetate the thrombolytic effect diminished by 45%. It is supposed that the leech-prostaglandins, like prostacyclin and its stable analogous, induce the release of tissue plasminogen activator from vessel walls. The thrombolytic effect of destabilase was demonstrated in experiments in vitro. We observed the phenomenon of increasing of glutaminase activity of citrate blood and the appearance of amidolytic and destabilase activity.

Animals↗
PubMedDate not supplied

Medicinal leech therapy: an overview (continuing education credit).

Leech therapy has made a comeback as a legitimate form of therapy for treating venous congestion following grafts and replants. Complications caused directly by leech therapy are minimal, as are the risks, while the benefits can be revascularization of replanted tissue. Nurses are integral in preparing patients for leech therapy.

Adult↗
PubMed1989

Digit replantation applying the leech Hirudo medicinalis.

Digits that were formerly assessed as nonreplantable may now be replanted with the help of the leech Hirudo medicinalis. The early experience with a series of patients who had relative contraindications for replantation is reported. In each case, venous repair was either marginal or technically impossible. Postoperative venous congestion developed following replantation and was treated with the application of medicinal leeches. Patient acceptance was high, and no infections developed. No patient required transfusion. The authors conclude that the use of medicinal leeches shows promise as a safe and effective method of providing temporary venous drainage in replanted digits.

Adolescent↗
PubMed1989

The leech Batracobdelloides tricarinata (Blanchard, 1897) (Hirudinea: Glossiphoniidae) as a possible reservoir of the rainbow trout pathogenic Streptococcus species.

A Streptococcus species biochemically and serologically identical to the rainbow trout pathogenic Streptococcus species was isolated from the internal organs of the fish specific leech, Batracobdelloides tricarinata. These leeches were obtained from Roodeplaat Dam, near Pretoria, in which rainbow trout do not occur. This is the first isolation of this bacterium from an environmental source not related to rainbow trout and it is proposed that this leech is a possible reservoir of the rainbow trout pathogenic Streptococcus sp. in South Africa.

Animals↗
PubMed1988

[Inhibition of kallikrein from human plasma by salivary gland secretion and extracts of the medicinal leech Hirudo medicinalis].

It has been shown for the first time that the salivary gland secretion of the medicinal leech (Hirudo medicinalis) contains a human blood plasma kallikrein inhibitor which is capable of blocking the amidolytic activity of the enzyme in an irreversible manner (with D-Pro-Phe-Arg-pNA as substrate) and which also suppresses the kininogenase activity of kallikrein. The inhibition of the amidolytic activity of highly purified kallikrein preparations from human blood plasma obeys the pseudo-first order kinetics. The experimental results suggest that in the salivary-gland secretion of H. medicinalis the inhibitor concentration exceeds by one order of magnitude that in whole leech homogenate extracts, which indicates that the inhibitor biosynthesis may be localized in leech salivary glands.

Animals↗
PubMed1987

[Morphofunctional characteristics of the vascular endothelium in the common leech (Clepsina complanta)].

The electron microscopic investigation has revealed in the body of the leech two types of vessels, that together with common signs possess a number of peculiarities in composition of endothelial cells. These vessels have different level of organization: the vessels of the first type, concerning the parenchyma of the leech, are nutritive, and the vessels of the second type combine capacitance and transport functions and are the place of hemolymph renovation at the expense of an active metabolic and synthetic activity of the endothelial cells. A fact is stated concerning a specific position of mitochondria in the endotheliocytes of the second type vessels: from the vessel's lumen they are not covered with plasmolemma along their whole extent and come into an immediate contact with hemolymph. Therefore, a hypothesis is suggested on functional activity of the endothelial cell mitochondria in the second type vessels. Presumptive differentiation of the two major vessels of the leech body makes it possible to suppose that there exist functional predecessors of the vessels of branchial and pulmonary type, that is vessels of lesser and greater circulation.

Animals↗
PubMed1987

Cell death during gangliogenesis in the leech: bipolar cells appear and then degenerate in all ganglia.

The bipolar cells can be recognized very early during gangliogenesis in the leech central nervous system by their expression of antigens that are recognized by the monoclonal antibody Laz1-1. They are the first cells to express these antigens, which are later shared with a distinct set of other cells in the leech nervous system. Their processes extend several segments rostrally and caudally along the forming interganglionic connective nerves; they are first found in anterior segments and gradually appear in more posterior ones over the course of 2-3 d. At about the time bipolar cells appear in the neuromeres of the tail ganglion, those in the most anterior segmental ganglia begin to degenerate. Degeneration proceeds caudally over the next 3 d, until all bipolar cells have disappeared. Bipolar cells are, thus, members of that class of cells that exists for only a short period in neurogenesis and then presumably disappears once its functions are no longer required. These cells' morphology and appearance at the earliest stages in the formation of the interganglionic connective nerves are suggestive of a role in the establishment of these longitudinal pathways in the leech CNS.

Animals↗
PubMed1987

[Mechanisms of inhibition of vascular-platelet hemostasis by salivary gland secretion of the medicinal leech Hirudo medicinalis].

The mechanism of inhibition of the vascular-platelet stage of hemostasis by medicinal leech salivary gland secretion was studied. It was shown that the secretion blocks platelet adhesion on the surface of collagens belonging to different genetic classes, inhibits the primary attachment of platelets and completely suppresses their spreading on collagen surface. Whatever its antithrombin activity, the leech secretion inhibits platelet aggregation stimulated by various inductors, e. g., ADP, prostaglandin endoperoxide analog U-46619, Ca2+ ionophore A23187, arachidonic acid. The secretion possessing the antithrombin activity causes a greater inhibition of the thrombin-stimulated aggregation than that devoid of this activity. Leech secretion stimulates adenylate cyclase of platelet membranes in a receptor-mediated fashion and increases the level of cAMP. The active substance is a low molecular weight, thermostable trypsin-resistant fraction of the secretion. Stimulation of adenylate cyclase is not mediated by adenosine receptors. It is supposed that the mechanism of this activating effect involves platelet prostaglandin receptors.

Adenylyl Cyclases↗
PubMed1985

Developmental neural kinship groups in the leech.

We have traced the developmental origins of various CNS neurons and glial cells of a leech to 10 clonally related groups of cells, the bilaterally paired M, N, O, P, and Q kinship groups. Each kinship group is descended from one of 10 identifiable blastomeres of the early embryo, the teloblasts. Of the approximately 200 neurons in each side of a segmental ganglion, 130 to 160 are in the ipsilateral N, 20 to 50 in the O, 8 to 12 in the P, 6 to 9 in the Q, and 3 to 6 in the M kinship group. A given identified neuron or glial cell was invariably found to belong to a particular kinship group, indicating that in leech development neuronal lineage is highly stereotyped. But cells of related function and morphology do not necessarily belong to the same neuronal kinship group: of the mechanosensory neurons, the T and N neurons belong to the N, the Pv neuron belongs to the P and the PD neuron belongs to the O kinship group. Similarly, glial cells arise from all four ectodermal teloblasts. Conversely, neurons within a kinship group are not obviously related in structure or function: the N kinship group includes sensory, motor, and effector neurons and interneurons: the O and P kinship groups each include sensory neurons and interneurons; both the P and Q groups contain representatives of three distinct morphological classes of interneurons. Consequently, in early development, the determinants of neuronal identity in the leech CNS are not segregated in any obvious thematic way in the cleavages that give rise to the five bilateral pairs of teloblasts. Rather, the neural kinship groups may be merely the evolutionary vestige of a primordial distributed nervous system, each quadrant of which was derived from one teloblast.

Animals↗
PubMed1983

Monoclonal antibodies demonstrate the organization of axons in the leech.

Monoclonal antibodies have been generated that bind to subsets of neurons within the leech central nervous system (Zipser, B., and R. McKay (1981) Nature 289: 549-554). In this report we describe the binding patterns of monoclonal antibodies to subsets of axons in the leech using HRP-immunohistochemistry. Each antibody has a characteristic staining pattern in the connective, the large bundle of axons that runs the length of the nerve cord connecting each ganglion to its rostral and caudal neighbors. These staining patterns are consistent along the rostrocaudal axis of each animal, between animals of the same species, and, in many cases, between animals of different species. These results show that axonal position, like neuron cell body position, is a consistent feature of the organization of the leech central nervous system. Two antibodies bind to all of the axons in particular fascicles that are delimited by glial cell processes; another binds to single axons in fascicles that contain other, unstained axons. The grouping of antibody-identified axons into fascicles does not correlate in a simple way with the grouping of neuron cell bodies identified with the same antibody. The presence of one of these antigens on the surface of axons suggests a possible role in axon fasciculation. This report shows that molecular heterogeneity is a property of axons as well as of neuron cell bodies and demonstrates the organization of specific antibody-identified groups of axons within the connective.

Animals↗
PubMed1984

Normal and abnormal development of an identified leech motor neuron.

In embryonic and mature leeches, the identified L motor neuron, which innervates the longitudinal muscles of the contralateral half body segment, can be identified by the location and relatively large size of its cell body. Here the morphological and physiological development of the L motor neuron has been investigated by intracellular recording and dye-filling techniques in normal and abnormal embryonic leeches. Normally the L motor neuron growth cone projects from the cell body at about the same time as from many other neurons located in the lateral part of the ganglion, including the P mechanosensory neurons. The L motor axon, like many other leech axons, projects directly into the appropriate pathway. The L motor neuron does not initially extend an excessive number of axons followed by elimination of the inappropriate ones. Its growth cone is tapered and relatively free of filopodia and grows out of the ganglion in the contralateral posterior nerve behind the growth cone of the primary peripheral axon of the dorsal P mechanosensory cell, which is one of the earliest axons in the posterior root. Occasionally the bilateral halves of the germinal plate fail to fuse resulting in an embryo with separated but intact half ganglia, body wall, and skin. In such embryos the L motor neuron axons cannot grow out of the contralateral posterior nerve since it is not available. Instead they grow out a variety of ipsilateral nerves and/or connective tracts. The P mechanosensory cells, which normally grow out of the ganglion in specific ipsilateral nerves, extend their axons along their normal pathways. In these abnormal embryos the L motor neurons did not preferentially grow into the ipsilateral posterior nerve, normally the pathway taken by the bilateral homologue and the nerve most similar to the L motor neuron's normal pathway. The failure of these L neurons to either consistently choose or avoid the ipsilateral posterior root suggests that the bilateral homologues ignore one another's pathfinding cues or that such cues are missing or changed in these embryos. The axons of the P neurons, however, appear to require no cues or interactions with contralateral structures or cells for normal development.

Action Potentials↗
PubMedDate not supplied

The dual role of serotonin in leech swimming.

The swimming behavior of the leech depends upon the level of serotonin in its blood stream: the higher the level, the more likely the leech is to swim. Serotonin is contained in Retzius cells, segmentally paired neurons, which release enough of this substance to affect its blood level and thus the swimming behavior of the animal. Retzius cells appear not to have synaptic effects on swim-related neurons. Pairs of other serotonin-containing neurons (cells 21 and 61) are also present in each ganglion. Stimulation of these cells can initiate swimming within seconds. In contrast to Retzius cells, neurons 21 and 61 make synaptic connections onto swim-related neurons; for example, cell 61 makes what appears to be a conductance decrease excitatory synapse onto the pattern-generating interneuron cell 208. These results suggest that the two classes of serotonin-containing neurons control the swimming behavior of the leech through two different mechanisms: Retzius cells exert a neurohormonal action whereas cells 21 and 61 act synaptically.

Animals↗
PubMed1995

Post menopausal vaginal bleeding due to vaginal wall leech infestation.

A 50 year old para vi patient was referred to Mekelle Hospital on October 23, 1992 with post menopausal vaginal bleeding and haemorrhagic shock to rule out endometrial carcinoma. She was anaemic. Speculum examination revealed a darkish mass attached to the posterior vaginal fornix. The mass was instilled with about 5 ml (1%) Lidocaine, after which it detached itself and started movement. The mass was an aquatic leech. Previously, post menopausal vaginal bleeding due to leech infestation was not reported, and therefore, this has to be included in the differential diagnosis of abnormal vaginal bleeding. Emphasis should also be made to create awareness among professionals working in areas where leech infestation is prevalent.

Anemia↗
PubMed1993

31P-NMR study on effects of electric shock on swimming leeches, Hirudo medicinalis.

1. We evaluated the effect of electric shock on swimming leeches by measuring changes in high-energy phosphate metabolism using in vivo 31P-NMR. 2. Leeches electrically stimulated during swimming showed anodal galvanotaxis and stopped swimming with stimulation at strong current. 3. Comparison of the concentrations of high-energy phosphate metabolites before and after electric shock using 31P-NMR revealed a marked decrease in beta-ATP and an increase in that of Pi. 4. Electric shock apparently induces excessive muscle fatigue in leeches, resulting in transient paralysis.

Animals↗
PubMed1994

The S cell: an interneuron essential for sensitization and full dishabituation of leech shortening.

Sensory neurons in the leech excite the S interneuron, which in turn excites motoneurons that shorten the leech, although activity in the S cell reportedly cannot by itself shorten the animal. Experiments were performed in semi-intact leeches using established dishabituation and sensitization protocols. S-cell activity increased during reflexive shortening once the animal was sensitized or dishabituated with a strong shock. S-cell activity otherwise was not associated with shortening. To test the role of the S-cell in dishabituation and sensitization of the shortening reflex, single S cells were ablated in vivo by intracellular injections of pronase. S-cell lesions reduced but did not eliminate dishabituation; however, sensitization was completely disrupted. This was consistent with recent evidence that separate processes contribute to dishabituation and sensitization. Since the S cell in each ganglion is a link in a rapidly conducting chain along the length of the animal, it may be sufficient to break the chain at a single point to eliminate sensitization.

Animals↗