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At least 307 records · Page 17Linked to original sources
PubMed1992

Evidence for angiotensin-like molecules in the central nervous system of the leech Theromyzon tessulatum (O.F.M.). A possible diuretic effect.

1. Cells in the central nervous system of the leech Theromyzon tessulatum were revealed with an antiserum against angiotensin II. Among these cells, a group of 4-5 pairs of neurons, called beta giant cells, and located in the posterior compartments of the supraesophageal ganglion was particularly investigated. 2. The amount of angiotensin II-like substance(s) in the brain increased notably in the days immediately following the third meal. 3. Injections of angiotensin II, fragments 1-4 or 5-8 or angiotensin II and of angiotensin III into stage 3 leeches showed that fragment 5-8 of angiotensin II was the most effective: it provokes a loss of mass of the leeches, which could express a diuretic effect.

Angiotensin II↗
PubMed1996

Biochemical evidence of the sodium influx stimulating related peptide in the brain of the leech Theromyzon tessulatum.

This paper reports the immunocytochemical and biochemical evidence of a sodium influx stimulating related peptide (SIS-like peptide) in the brain of the leech Theromyzon tessulatum. Cells immunoreactive to both polyclonal antisera raised against the N-terminal (fragment 10-19) or the C-terminal (fragment 67-76) sequences of the purified freshwater snail Lymnaea stagnalis sodium influx stimulating peptide (SISP) was detected in the brain of this leech. These immunocytochemical data were strengthened by biochemical results at the level of the protein and by in vitro translated RNA. By combined techniques i.e. high performance gel permeation chromatography, electrophoresis followed by immunoblot analysis with the two antisera and immunoprecipitation, we established the existence in leeches of a protein of ca 11 kDa and its precursor, a protein of ca 13 kDa related to the SISP. Moreover, results of injections of anti-SISP (10-19) preabsorbed or not with its homologous antigen to Theromyzon tessulatum confirmed the SIS-like substance involvement in osmoregulation by an anti-diuretic function.

Animals↗
PubMed1984

The halomethylketone derivative L-Glu-gamma-DL-Ala-CH2Cl and N-methyl-D-aspartate as selective antagonists against L-glutamate and kainate excitation respectively on Retzius cells of the leech, Hirudo medicinalis.

Intracellular recordings were made from leech Retzius cells. The action of a range of putative antagonists was examined on the excitatory responses to dicarboxylic amino acids which were applied via a diffusion electrode. The halomethylketone derivative, L-Glu-gamma-DL-Ala-CH2Cl was found to block preferentially the L-glutamate response compared to the kainate response. This compound had no effect on the response to carbachol. N-Methyl-D-aspartate was found to block the response to kainate while having no effect on the responses to L-glutamate, ibotenate or carbachol. This compound had no direct action on the cell. N-Methyl-D-aspartic acid also reduced the excitatory responses to methyltetrahydrofolate and 3- carboxymethylpyrrolidine -2,4-dicarboxylic acid ( CMPDA ). gamma-D-Glutamyl-amino methyl-sulphonate ( GAMS ), while partially blocking the action of kainate, had no effect on the response to ibotenate. gamma-D-Glutamylglycine was found to reduce the response to L-glutamate, ibotenate, kainate, quisqualate and CMPDA . CMPDA , a tricarboxylic acid derivative of kainate, was found to be approximately equipotent with kainate on leech Retzius cells. This compound was partially blocked by N-methyl-D-aspartate. The present study demonstrates that it is possible to differentially block L-glutamate and kainate on leech Retzius cells and indicates that they are acting on separate components of the membrane.

Amino Acid Chloromethyl Ketones↗
PubMed1985

Sensitivity of the resting sodium conductivity of leech Retzius nerve cells to tetrodotoxin.

Simultaneously, the effect of sodium-free medium and tetrodotoxin (3 X 10(-8) M/ml) were investigated on some passive electrophysiological properties of leech Retzius nerve cells. Complete replacement of Na+ with Tris or addition of tetrodotoxin to the leech Ringer was followed by an increase of input resistance in contrast to the cell-to-cell interaction which was not affected by such a procedure. At the same time tetrodotoxin was not able to block repetitive spike activity. The data imply the existence of two types of Na+ channel in leech Retzius nerve cells.

Animals↗
PubMed1987

The saliva of the medicinal leech Hirudo medicinalis--II. Inhibition of platelet aggregation and of leukocyte activity and examination of reputed anaesthetic effects.

1. Leech saliva inhibits platelet aggregation induced by collagen, ADP and epinephrine. 2. Leech saliva inhibits superoxide production by neutrophils stimulated by tetradecanoyl phorbol acetate or polyhistidine. The effect is due in part at least to eglin. 3. Reputed anaesthetic effects of leech saliva were not detected.

Adenosine Diphosphate↗
PubMed2004

Crabs, leeches and trypanosomes: an unholy trinity?

The red king crab Paralithodes camtschaticus was deliberately introduced to the Barents Sea in the 1960s and 1970s from its native area in the North Pacific. The carapace of these crabs is a favoured substrate for the leech Johanssonia arctica to deposit its eggs, and the leech is a vector for a trypanosome blood parasite of marine fish, including cod. We examined cod for trypanosome infections during annual cruises along the coast of Finnmark in North Norway over three successive years from stations along a gradient of over 1000 km. In every year the level of trypanosome infection in cod was significantly highest in the area with the greatest density of king crabs. We propose the hypothesis that the burgeoning population of red king crabs in this area is indirectly responsible for increased transmission of trypanosomes to cod by promoting an increase in the population of the leech vector.

Animals↗
PubMed2006

Leeches and their microbiota: naturally simple symbiosis models.

Strictly blood-feeding leeches and their limited microbiota provide natural and powerful model systems to examine symbiosis. Blood is devoid of essential nutrients and it is thought that symbiotic bacteria synthesize these for the host. In this review, three distinct leech-microbe associations are described: (i) the mycetome, which is the large symbiont-containing organ associated with the esophagus; (ii) the nephridia and bladders that form the excretory system; and (iii) the digestive tract, where two bacterial species dominate the microbiota. The current knowledge and features of leech biology that promote the investigation of interspecific interactions (host-microbe and microbe-microbe) and their evolution are highlighted.

Animals↗
PubMed2004

The Ozobranchus leech is a candidate mechanical vector for the fibropapilloma-associated turtle herpesvirus found latently infecting skin tumors on Hawaiian green turtles (Chelonia mydas).

Fibropapillomatosis (FP) of marine turtles is a neoplastic disease of ecological concern. A fibropapilloma-associated turtle herpesvirus (FPTHV) is consistently present, usually at loads exceeding one virus copy per tumor cell. DNA from an array of parasites of green turtles (Chelonia mydas) was examined with quantitative PCR (qPCR) to determine whether any carried viral loads are sufficient to implicate them as vectors for FPTHV. Marine leeches (Ozobranchus spp.) were found to carry high viral DNA loads; some samples approached 10 million copies per leech. Isopycnic sucrose density gradient/qPCR analysis confirmed that some of these copies were associated with particles of the density of enveloped viruses. The data implicate the marine leech Ozobranchus as a mechanical vector for FPTHV. Quantitative RT-PCR analysis of FPTHV gene expression indicated that most of the FPTHV copies in a fibropapilloma have restricted DNA polymerase expression, suggestive of latent infection.

Animals↗
PubMed2004

Cell cycle-dependent expression of a hairy and Enhancer of split (hes) homolog during cleavage and segmentation in leech embryos.

We have cloned genes related to hairy and Enhancer of split (hes) from glossiphoniid leeches, Helobdella robusta and Theromyzon rude. In leech, segments arise sequentially in anteroposterior progression from a posterior growth zone that consists of five bilaterally paired embryonic stem cells called teloblasts. Each teloblast gives rise to segmental founder cells (primary blast cells) that contribute iterated sets of definitive progeny in each segment. Thus, in leech, the "segmentation clock," is closely identified with the cell cycle clock of the teloblasts. We have characterized normal expression patterns of mRNA and protein for the H. robusta hes-class gene (Hro-hes). Semiquantitative RT-PCR revealed that Hro-hes mRNA levels peak while the teloblasts are actively producing primary blast cells. RT-PCR, in situ hybridization and immunostaining revealed that Hro-hes is expressed as early as the first zygotic mitosis and throughout early development. Hro-hes is expressed in macromeres, pro-teloblasts, teloblasts and primary blast cells. HRO-HES protein is localized in the nuclei of cells expressing HRO-HES during interphase; nuclear HRO-HES is reduced during mitosis. In contrast, Hro-hes is transcribed during mitosis and its transcripts are associated with mitotic apparatus (MA). Thus, Hro-hes transcription cycles in antiphase to the nuclear localization of HRO-HES protein. These results indicate that Hro-hes expression, and thus possibly its biological activity, is linked to the cell cycle.

Animals↗
PubMed2004

The occurrence of an Australian leech species (genus Helobdella) in German freshwater habitats as revealed by mitochondrial DNA sequences.

The freshwater leech Helobdella europaea Kutschera 1987 was discovered twenty years ago in Germany and described as a new species. Here, we show that this leech is genetically identical with the Australian species Helobdella papillornata (CO-I-mt-DNA sequence identity of alignment positions: 98%). We conclude that H. europaea (syn. H. papillornata) represents an introduced annelid that occupies the same ecological niche as the common European leech H. stagnalis L.

Animals↗
PubMed2003

Leech responses to tissue transplantation.

The aim of the present work is to describe histologically, histochemically and immunocytochemically, the sequence of events that lead to first and second set rejection of allo- or xenograft in leeches. Graft responses of leeches are comparable and are described following specific steps: inflammatory phase, rejection phase and granulation tissue formation (including re-epithelialisation, angiogenesis and fibroplasia).The responses to first and second graft in first set graft rejection as well as to the first transplant in second set graft experiments are identical and in the time span of a week all grafts are destroyed and disappear. In the second set graft rejection experiments the responses against the second transplant are markedly accelerated. The second graft shows massive structural alterations and it is rapidly rejected, within 3-4 days.Our results permit to highlight that in leeches there is a specific responsiveness of immune system similar to those described in highly divergent phyla.

Animals↗
PubMed2002

A nasopharyngeal mass: leech in the nasopharynx.

This paper presents a case with a 4-month history of nasal obstruction and intermittent epistaxis. The cause was found to be a leech in the nasopharynx by means of endoscopic examination. Leech endoparasitism, although rare, may cause serious, even lethal, complications. A high index of suspicion of leech infestation must be entertained when faced with nasal obstruction and intermittent epistaxis in children, and should be investigated surgically as with all other foreign bodies.

Adolescent↗
PubMedDate not supplied

Removal of a laryngeal leech: A safe and effective method.

This article presents a case of hoarseness, dysphagia, and hemoptysis caused by the laryngeal localization of a leech. This pathological condition is extremely rare in urban areas but is frequent in endemic rural areas. Laryngoscopic evaluation of our patient has shown a leech lodged on the left arytenoid region hanging down to larynx. We present a patient living in an urban area with laryngeal leech that was removed under general induction anesthesia of sevoflurane via a face mask without endotracheal intubation.

Adult↗
PubMed1998

Medicinal leeches used to salvage a traumatic nasal flap.

We report a case in which medicinal leeches (Hirudo medicinalis) were used to rescue a traumatic nasal flap from venous congestion and loss. A healthy 18-year-old had a bicycling accident and, in addition to other facial injuries, presented with a complex full thickness nasal laceration. After he had been resuscitated and the flap sutured, he was treated with two leeches four times a day for 48 h. His recovery was satisfactory and uncomplicated. Oral and maxillofacial surgeons should be familiar with the use of leeches, as they have a small but occasionally important role in the management of both traumatic and reconstructive flaps.

Adolescent↗
PubMed1997

Leeches in the larynx.

This is a report of two patients with leech inhalation. The first patient presented with severe attacks of inspiratory stridor, cyanosis and cough of five days duration. He had no fever. Indirect laryngoscopy revealed a black, smooth foreign body between the vocal folds. Lateral soft tissue X-ray of the neck revealed shadow involving the glottic and the subglottic areas of the larynx. Laryngoscopy under general anaesthesia showed a living leech. This was removed and the patient improved. The second patient presented with difficulty of breathing, dysphagia, and spitting of blood of two weeks duration. Indirect laryngoscopy revealed a brown foreign body in the larynx. Laryngoscopy under general anaesthesia showed a living leech. This was removed by forceps.

Adult↗
PubMed2001

Dystrophin-associated proteins in obliquely striated muscle of the leech Pontobdella muricata (Annelida, Hirudinea).

The distribution of dystrophin-associated proteins (beta-dystroglycan, alpha-, beta-, gamma- and delta-sarcoglycan, alpha-syntrophin and sarcospan) were studied in obliquely striated muscle of the leech Pontobdella muricata. Western blot analysis and immunohistochemical electron microscopy, using various polyclonal antibodies, were employed. Western blot analysis of all of these antibodies showed a single band, with approximately the same molecular weights as similar proteins detected in vertebrate muscles. The immunoelectron microscopy study confirmed specific immunogold labelling in the membrane of muscle cells. Since all dystrophin complex components have similar molecular weights and the same localisation in leech as in vertebrate skeletal muscle, we assume that these proteins have similar properties in leech and vertebrate muscle. The presence of these molecules in annelid muscles, together with a short version of dystrophin (previously described as IDLp-140) is of particular interest since phylogenetic and functional studies on this material could help to shed new light on the role and function of this complex in the muscle membrane.

Animals↗
PubMed1994

Serotonin depletion impairs but does not eliminate classical conditioning in the leech Hirudo medicinalis.

The goal of these experiments was to test the role of serotonin (5HT) in classical conditioning of the touch-elicited shortening reflex in the leech (Hirudo medicinalis). The toxin 5,7-dihydroxytryptamine (5,7-DHT) was used to deplete serotonin. The results indicated that 5HT depletion significantly impairs the expression of conditioned responding; however, depleted leeches experiencing conditioned stimulus-unconditioned stimulus (CS-US) pairings still performed significantly better than depleted leeches experiencing unpaired CS-US presentations, suggesting that a 5HT-dependent mechanism does not account fully for learning in this preparation. Moreover, the residual pairing dependent effect is observed, although the depletions eliminate sensitization, suggesting that the amplification of sensitization may not be sufficient to account for classical conditioning of this reflex. Histological analyses of the ganglia revealed an absence of staining in 100% of the Retzius cells in the toxin group.

Animals↗
PubMedDate not supplied

Visual processing in the leech central nervous system.

In animals with complex visual systems spatial contrast is enhanced by mutual inhibition between retinal neurones monitoring different fields. By analogy, if animals like leeches and some caterpillars, that have several simple (non-image-forming) eyes aimed in different directions, are capable of rudimentary form detection, one might predict mutual antagonism between eyes monitoring different fields. In support of this prediction, I report here a paired interneurone in the central nervous system (CNS) of the leech which is stimulated by eyes on one side of the animal and inhibited by eyes on the other. There are striking parallels between these neurones and other integrating neurones, in particular those processing bilateral auditory input in crickets, suggesting that the visual system of the leech may be representative of a general class of sensory processing systems.

Action Potentials↗