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PubMed1989

Development of Trypanoplasma borreli (Mastigophora: Kinetoplastida) in the leech vector Piscicola geometra and its infectivity for the common carp, Cyprinus carpio.

The development of Trypanoplasma borreli in the crop of the leech vector Piscicola geometra was characterized by significant changes in morphology. Immediately after ingestion by the leech, stumpy-shaped T. borreli predominated and numerous dividing specimens were found. This led to long and slender trypanoplasms near the end of the infection. The infection was terminated with complete digestion of the blood stored in the crop of the leech. The longest period of infection observed was 11 days. Trypanoplasma borreli was found only in the crop of the leech. At any time during the infection, T. borreli isolated from P. geometra cause a parasitemia when inoculated into parasite-free carp. There was no difference in morphology or infectivity among T. borreli isolated from various crop regions of P. geometra.

Animals↗
PubMed1988

Associative learning modifies two behaviors in the leech, Hirudo medicinalis.

We report that 2 behaviors, stepping and shortening, are modified by associative learning in the leech, Hirudo medicinalis. Experiment 1 explored conditioning of the "stepping" response. Paired presentations of touch to the medial dorsal surface of the leech and shock to the tail of the leech resulted in the development of stepping to the touch. Leeches in control groups experiencing the CS alone, US alone, or explicitly unpaired presentations of the CS and US did not. In experiments 2-4, classical conditioning explored conditioning of the touch-elicited shortening reflex. We found that the reflex was enhanced following paired CS-US presentations but not following CS alone, US alone, or explicitly unpaired presentations of the stimuli. Moreover, the learning was extinguished following 15 unreinforced presentations of the CS but was retained for at least 24 hr without extinction training. Moreover, the associative effect was not evident when the CS and US were presented in a backward relationship. That is, no learning was observed when the US preceded the CS. Lastly, the hand-held stimuli were replaced with implanted electrodes. Using a 3 V pulse that mimicked the touch stimulus (CS), we found that paired CS-US presentations produced a significant enhancement in the shortening reflex. Again, no enhancement was observed following unpaired CS, US presentations.

Animals↗
PubMed1986

Gangliogenesis in leech embryos: migration of neural precursor cells.

In the metameric CNS of leeches, identified neurons occupy highly stereotyped positions in each segmental ganglion. Although many of the neural precursor cells arise near their definitive positions, some arise outside the prospective domain of the segmental ganglia and thus must migrate into the CNS. Here, we report the results of an analysis of the role of cell migration in gangliogenesis in the leech Theromyzon rude. Segmental ganglia of the ventral nerve cord arise as laterally thickened sheets of tissue lying astride the ventral midline. Particular identified circular and longitudinal muscle fibers, visualized by indirect immunofluorescence using a monoclonal antibody against leech muscle, outline the presumptive ganglionic territories even before the ganglionic rudiments become morphologically distinct and serve as anatomical landmarks to which the cell movements are related. Cell lineage tracers microinjected into precursor blastomeres are used to visualize migratory cells. Small groups of neural precursor cells that arise outside the prospective ganglionic territories migrate with stereotyped timing along stereotyped pathways to reach their definitive positions, and each group of migratory cells gives rise to a stereotyped subset of the cells in a ganglion. No segmental or regional differences are observed in any aspect of cell migration studied here, supporting the view that segmental differences in the architecture of the leech CNS arise only after the initial condensation of the ganglionic rudiments.

Animals↗
PubMed1983

The expression of antigens by embryonic neurons and glia in segmental ganglia of the leech Haemopis marmorata.

Monoclonal antibodies (mAbs) raised against adult leech nervous systems were screened on embryos of the leech Haemopis marmorata in order to determine when in development specific antigens are first expressed and the order in which they are expressed by different cells or tissues. Three of the mAbs produced by Zipser and McKay (Zipser, B., and R. McKay (1981) Nature 289: 549-554) were screened: Lan3-1, Lan3-5, and Lan3-6. Each mAb shows a different pattern of labeling in the adult leech nerve cord (Zipser, B. (1982) J. Neurosci. 2: 1453-1464). The embryonic stages studied were from 5 days after egg deposition to 30 days (emergence from the cocoon). The pattern of labeling was assayed in whole mounts using horseradish peroxidase-conjugated second antibodies. The principal results are as follows. (1) Antigens recognized by Lan3-5 are first expressed by the glia of the roots of the anterior segmental ganglia at 6 to 7 days, several days later by the interganglionic connective glia, and near the end of embryonic development by ganglionic neurons. An anterior to posterior temporal gradient is observed in the expression of these antigens. In addition, Lan3-5 also labels the protonephridia and nephridia from early development onward. (2) Antigens recognized by Lan3-6 are first expressed by a pair of neurons in each segmental ganglion and later in development by additional neurons. By the time of emergence, however, only about half of the neurons that label in the adult have done so, implying that some neurons express these antigens postembryonically. Labeling with Lan3-6 is first seen in neuronal somata and only later in neuronal processes. (3) Antigens recognized by Lan3-1 and expressed by segmentally specific neurons in ganglia 5 and 6 are not detectable during embryonic development, but are so at early postembryonic stages. Thus, these three mAbs provide an approach to study different aspects of the development of the leech nervous system, specifically the relation between glial and neuronal differentiation and the genesis of segmentally specific phenotypes.

Animals↗
PubMed1981

Appearance and localization of acetylcholinesterase in embryos of the leech Helobdella triserialis.

The appearance and localization of acetylcholinesterase (AchE) were studied during embryonic development of the leech Helobdella triserialis. Use of a histochemical stain showed that AchE is present in the polar plasms of the uncleaved leech egg. in the course of the first two cleavages, the AchE is transmitted along with the polar plasms mainly to the D blastomere, precursor of mesoderm and ectoderm. At these early developmental stages, AchE also lines the cleavage furrows between the blastomeres. At later stages, AchE is present in the parental meso- and ectoteloblasts and their daughter stem cells that form the germinal bands. At the completion of germinal band coalescence, AchE is present in the rostral and caudal regions of the germinal plate. Thus, the presence of AchE in the early phase of embryogenesis precedes the formation of any nervous tissue. In the late phase of embryogenesis, once the embryo has reached the stage of body closure and a nervous system is present, the distribution of AchE is that characteristic of the adult leech: AchE is localized in the neuropil of the segmental ganglia of the ventral nerve cord and in the musculature of the body wall. Therefore, at this still quite immature stage, the embryonic nervous system has taken on not only the morphological but also some of the neurochemical characteristics of the adult leech.

Acetylcholinesterase↗
PubMedDate not supplied

Medicinal leeches in the postoperative care of bladder exstrophy.

This article reports the use of medicinal leech therapy for the relief of severe postoperative vascular congestion of the penis in a male infant with exstrophy of the bladder. When more conventional methods of decongestion were unsuccessful, medicinal leech therapy markedly improved the infant's chance of remaining both phenotypically and functionally male. The uneventful and successful use of medicinal leeches in this patient demonstrates that medicinal leeches may be safely used in the newborn period, if appropriate precautions are taken to prevent both infection and anemia.

Animals↗
PubMed1995

Leech therapy for venous congestion following myocutaneous pectoralis flap reconstruction.

Medicinal leech therapy is recorded as early as 200 B.C. to treat everything from mental illness to headaches. The medicinal leech (Hirudo medicinalis) is used today as a successful treatment for venous congestion following replantation or transplantation of tissue. This paper discusses specific leeching properties, indications for use, nursing care and expected outcomes of leech therapy.

Animals↗
PubMed1994

The use of medicinal leeches, Hirudo medicinalis, to restore venous circulation in trauma and reconstructive microsurgery.

Following replantation of complete or incomplete nonviable amputations of digits and hands, as well as microsurgical free tissue transfer, there is often a critical need for adjuvant therapy in order to restore sufficient venous drainage. In 24 out of 29 patients, venous insufficiency was successfully treated with the use of medicinal leeches. In a group of patients who had undergone replantation procedures (11 patients total), 9 patients (8 with digit and 1 with hand amputations) had venous drainage successfully restored with medicinal leeches, while in a group of patients who had free tissue transfers (18 patients total), 15 had the venous congestion treated successfully with leeches. The results indicate that medicinal leeches are a valuable, alternative method for the treatment of venous congestion in both replantation patients and those who have undergone free tissue transfer.

Adolescent↗
PubMed1995

[Antithrombotic effect of piavit--a substance from the medicinal leech (Hirudo medicinalis), containing prostanoid and destabilase fractions].

The protective antithrombotic effects of piyavit, a novel pharmacological preparation from the medicinal leech, its water extract concentrated and diluted 1600-fold, the piyavit fraction containing leech prostanoids and highly purified destabilase, epsilon-(gamma-Glu)-Lys-isopeptidase isolated from the medicinal leech (Hirudo medicinalis), have been studied. All the preparations under study inhibited clot formation in rat mesanterium arterioles stimulated by laser energy, contained leech prostanoids immunoenzymatically identified as 6-keto-PgF1 alpha and inhibited platelet aggregation induced by ADP. The putative mechanism of their antithrombotic effect is discussed.

Animals↗
PubMed2006

Modification of leech behavior following foraging for artificial blood.

In this study we examined whether the foraging for artificial blood affected the behavioral responsiveness of leeches to electrical stimulation of the body wall. After foraging for artificial blood, electrical stimulation of the posterior end of the leech significantly increased the percentage of stimulation trials that elicited locomotory activity--swimming and crawling--compared to the behaviors elicited when leeches did not forage or foraged for normal saline. On the other hand, shortening always dominated the behavioral profile of the leech to anterior stimulation even after foraging for artificial blood. In intact anterior end-isolated nerve cord preparations, we also found that application of artificial blood to the intact anterior end was sufficient to modify motor responsiveness to DP nerve stimulation. Full strength artificial blood had an overall negative effect on the likelihood of DP nerve stimulation initiating swimming and on the average length of elicited swim episodes compared to when pond water surrounded the anterior end. Application of a 10% solution of artificial blood to the anterior end led to an increase in the likelihood of DP nerve stimulation eliciting swimming.

Action Potentials↗
PubMed2004

Up-regulation of neurohemerythrin expression in the central nervous system of the medicinal leech, Hirudo medicinalis, following septic injury.

We report here some results of a proteomic analysis of changes in protein expression in the leech Hirudo medicinalis in response to septic injury. Comparison of two-dimensional protein gels revealed several significant differences between normal and experimental tissues. One protein found to be up-regulated after septic shock was identified, through a combination of Edman degradation, mass spectrometry, and molecular cloning, as a novel member of the hemerythrin family, a group of non-heme-iron oxygen transport proteins found in four invertebrate phyla: sipunculids, priapulids, brachiopods, and annelids. We found by in situ hybridization and immunocytochemistry that the new leech protein, which we have called neurohemerythrin, is indeed expressed in the leech central nervous system. Both message and protein were detected in the pair of large glia within the ganglionic neuropile, in the six packet glia that surround neuronal somata in each central ganglion, and in the bilateral pair of glia that separate axonal fascicles in the interganglionic connective nerves. No expression was detected in central neurons or in central nervous system microglia. Expression was also observed in many other, non-neuronal tissues in the body wall. Real-time PCR experiments suggest that neurohemerythrin is up-regulated posttranscriptionaly. We consider potential roles of neurohemerythrin, associated with its ability to bind oxygen and iron, in the innate immune response of the leech nervous system to bacterial invasion.

Amino Acid Sequence↗
PubMed2005

Mg2+-malate co-transport, a mechanism for Na+-independent Mg2+ transport in neurons of the leech Hirudo medicinalis.

Mg2+-extrusion from Mg2+-loaded neurons of the leech, Hirudo medicinalis, is mediated mainly by Na+/Mg2+ antiport. However, in a number of leech neurons, Mg2+ is extruded in the nominal absence of extracellular Na+, indicating the existence of an additional, Na+-independent Mg2+ transport mechanism. This mechanism was investigated using electrophysiological and microfluorimetrical techniques. The rate of Na+-independent Mg2+ extrusion from Mg2+-loaded leech neurons was found to be independent of extracellular Ca2+, K+, NO3-, HCO3-, SO4(2-), HPO4(2-), and of intra- and extracellular pH. Na+-independent Mg2+ extrusion was not inhibited by 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS), furosemide, ouabain, vanadate, iodoacetate, 4-amino-hippurate, or alpha-cyano-4-hydroxycinnamate and was not influenced by changes in the membrane potential in voltage-clamp experiments. Na+-independent Mg2+ extrusion was, however, inhibited by the application of 2 mM probenecid, a blocker of organic anion transporters, suggesting that Mg2+ might be co-transported with organic anions. Extracellularly, of all organic anions tested (malate, citrate, lactate, alpha-ketoglutarate, and 4-amino-hippurate) only high, but physiological, concentrations of malate (30 mM) had a significant inhibitory effect on Na+-independent Mg2+ extrusion. Intracellularly, iontophoretically injected malate, citrate, or fura-2, but not Cl-, alpha-ketoglutarate, glutamate, succinate, or urate, were stimulating Na+-independent Mg2+ extrusion from those neurons that initially did not extrude Mg2+ in Na+-free solutions. Our data indicate that Mg2+ is co-transported with organic anions, preferably with malate, the predominant extracellular anion in the leech. The proposed model implies that, under experimental conditions, malate drives Mg2+ extrusion, whereas under physiological conditions, malate is actively taken up, driven by Mg2+, so that malate can be metabolized.

Analysis of Variance↗
PubMed2005

Location and intensity discrimination in the leech local bend response quantified using optic flow and principal components analysis.

In response to touches to their skin, medicinal leeches shorten their body on the side of the touch. We elicited local bends by delivering precisely controlled pressure stimuli at different locations, intensities, and durations to body-wall preparations. We video-taped the individual responses, quantifying the body-wall displacements over time using a motion-tracking algorithm based on making optic flow estimates between video frames. Using principal components analysis (PCA), we found that one to three principal components fit the behavioral data much better than did previous (cosine) measures. The amplitudes of the principal components (i.e., the principal component scores) nicely discriminated the responses to stimuli both at different locations and of different intensities. Leeches discriminated (i.e., produced distinguishable responses) between touch locations that are approximately a millimeter apart. Their ability to discriminate stimulus intensity depended on stimulus magnitude: discrimination was very acute for weak stimuli and less sensitive for stronger stimuli. In addition, increasing the stimulus duration improved the leech's ability to discriminate between stimulus intensities. Overall, the use of optic flow fields and PCA provide a powerful framework for characterizing the discrimination abilities of the leech local bend response.

Animals↗
PubMed2005

Statistics of decision making in the leech.

Animals continuously decide among different behaviors, but, even in invertebrates, the mechanisms underlying choice and decision are unknown. In this article, leech spontaneous behavior was tracked and quantified for up to 12 h. We obtained a statistical characterization, in space and time domains, of the decision processes underlying selection of behavior in the leech. We found that the spatial distribution of leech position in a uniform environment is isotropic (the same in all directions), but this isotropy is broken in the presence of localized external stimuli. In the time domain, transitions among behaviors can be described by a Markov process, the structure of which (allowed states and transitions) is highly conserved across individuals. Finally, a wide range of recurrent, deterministic motifs was identified in the apparently irregular and unstructured exploratory behavior. These results provide a rigorous description of the inner dynamics that control the spontaneous and continuous flow of behavioral decisions in the leech.

Animals↗
PubMed2005

[Leeches, today and yesterday present parasites].

Leeches are flattened annelids or segmented worms that live in still, warm waters of the pond or in land. They feed of blood or body fluids. Medicinal leeches (Hirudo medicinalis) have been used in medicine for thousands of years to treat a wide range of ailments. Nowadays, leeches are used successfully for only a few conditions, notably in the field of reconstructive or microsurgery, to salvage tissue flaps and skin grafts whose viability is threatened by venous congestion. However, it is also important to keep it in mind as a differential diagnosis in some circumstances. This review pretends to give an actualize view of a subject that is a part of medical history.

Animals↗
PubMed1997

Developmental changes of potassium currents of embryonic leech ganglion cells in primary culture.

The expression of calcium-activated potassium currents (IK(Ca)), delayed outward rectifier potassium currents (IK(slow)), and transient outward currents (IA) was studied during the development of the nervous system of the leech using the whole-cell patch-clamp recording technique. Dissociated cells were isolated from leech embryos between stage E7 and E16 and maintained in primary culture. K+ currents were recorded at E7, when only few anterior ganglia had formed beneath the primordial mouth. IK(slow) was present in all cells tested, while IK(Ca) was expressed in only 67% of the cells studied. Even as early as E7, different types of IK(Ca) have been found. Neither frequency of occurrence nor the charge density of IK(Ca) showed significant changes between E7 and E16. The density of IK(slow), however, increased by a factor of two between E7 and E8, which resulted in a significant increase in the total K+ current of these cells. This rise in potassium outward current developed in parallel with the appearance of Na+ and Ca2+ inward currents (Schirrmacher and Deitmer: J Exp Biol 155:435-453, 1991) during early development, shaping the electrical excitability in embryonic leech neurones. I(A) could be separated by its voltage-dependence and pharmacological properties. The current was detected at stage E9, when all 32 ganglia are formed in the embryo. The frequency of occurrence of I(A) increased from 16% at E9 to 70% at E15. The channel density, steady state inactivation, and kinetics showed no significant changes during development.

Animals↗
PubMed1994

Leech segmentation: a molecular perspective.

A variety of leech homeobox genes have been identified by homology with genes that are known to bring about the regionalization and segmentation of the anteroposterior body axis in other organisms. Embryonic expression patterns suggest a number of interphyletic similarities in the way that these genes are utilized. However, several interesting differences have also been observed. In particular, transplantation experiments in the leech embryo have shown that axially aligned patterns of homeobox gene expression are not specified by a global pattern of positional cues. Rather, the leech independently establishes anteroposterior patterns of gene expression in each of five discrete stem cell lineages, and these patterns are brought into their final alignment through a process of morphogenetic assembly.

Animals↗
PubMed2006

Characterization of central axon terminals of putative stretch receptors in leeches.

Sensory feedback from stretch receptors, neurons that detect position or tension, is crucial for generating normal, robust locomotion. Among the eight pairs of putative stretch receptors associated with longitudinal muscles in midbody segments of medicinal leeches, only the ventral stretch receptor has been characterized in detail. To achieve the identification of all such receptors, we penetrated large axons in the nerve roots of nerve cords from adult leeches with dye-filled (Alexa Fluor hydrazide) electrodes. We identified the terminal arborizations of two additional putative stretch receptors with axons in anterior nerve roots and four more such receptors with axons in posterior roots of midbody ganglia. The axons are nonspiking and are individually identifiable by their entry point into the CNS; their projections within the neuropile; the pattern, extent, and orientation of their terminal branches; and the characteristics of small "spike-like" events. At least two of these axons undergo membrane potential oscillations that are phase locked to the swimming rhythm expressed in nerve cord-body wall preparations and, at a different phase angle, also in isolated nerve cords. Thus the membrane potentials of at least two axons are phasically modulated by the periphery and hence could provide cycle-by-cycle sensory input to coordinate swimming activity. One of these neurons has a soma associated with the dorsal body wall and hence is a putative stretch receptor in dorsal longitudinal muscle. Thus the traveling body wave expressed by swimming leeches may be regulated by sensory feedback from both ventral and dorsal longitudinal muscles.

Action Potentials↗