Ammonia formation in the medicinal leech, Hirudo medicinalis—in vivo and in vitro investigations

1989 ◽  
Vol 94 (2) ◽  
pp. 187-194 ◽  
Author(s):  
Peter Tschoerner ◽  
Ernst Zebe
Keyword(s):  
Medicinal Leech ◽  
Hirudo Medicinalis ◽  
Ammonia Formation

scholarly journals Hirudo medicinalis as alternative model for in vivo and in vitro studies on nanomaterials toxicity

2016 ◽  
Vol 258 ◽  
pp. S72
Author(s):  
R. Girardello ◽  
M. De Eguileor ◽  
G. Tettamanti ◽  
R. Valvassori ◽  
A. Grimaldi
Keyword(s):  
Alternative Model ◽  
Hirudo Medicinalis ◽  
In Vitro Studies

scholarly journals Calin from Hirudo medicinalis, an inhibitor of platelet adhesion to collagen, prevents platelet-rich thrombosis in hamsters

Blood ◽  
1995 ◽  
Vol 85 (3) ◽  
pp. 712-719 ◽  
Author(s):  
H Deckmyn ◽  
JM Stassen ◽  
I Vreys ◽  
E Van Houtte ◽  
RT Sawyer ◽  
...  
Keyword(s):  
Platelet Adhesion ◽  
Bleeding Time ◽  
Ex Vivo ◽  
Thrombus Formation ◽  
Femoral Vein ◽  
Video Recording ◽  
Hirudo Medicinalis ◽  
Thrombosis Model

Interaction between exposed collagen and platelets and/or von Willebrand factor is believed to be one of the initiating events for thrombus formation at sites of damaged endothelium. Interference with this mechanism may provide an anti-thrombotic potential. Calin, a product from the saliva of the leech Hirudo medicinalis, was tested in vitro and for its in vivo activity in a thrombosis model in hamsters. Calin specifically and dose dependently (IC50:6.5 to 13 micrograms/mL) inhibited human platelet aggregation induced by collagen. In addition, specific platelet adhesion onto microtiter wells coated with collagen and detected with a monoclonal antiglycoprotein IIb/IIIa antibody- conjugated with horseradish peroxidase, could be completely prevented with Calin (IC50:22 micrograms/mL). A dose-response curve was constructed in groups of six hamsters in whom a standardized trauma was induced on the femoral vein. Thrombus formation was followed continuously using video recording and processing of the image obtained upon transillumination of the vessel. Intravenous Calin dose- dependently inhibited platelet-rich thrombus formation in this model with an ED50 of 0.07 mg/kg and complete inhibition with 0.2 mg/kg. No effects were seen on coagulation tests or bleeding times, whereas ex vivo aggregation induced by collagen was inhibited dose dependently. Local application of leech saliva, Calin, hirudin, or the combination of the latter two into the bleeding time wound of hamsters resulted in a mild prolongation of the bleeding time (twofold to threefold). A similar experiment in baboons did not cause any prolongation of the bleeding time. This is in sharp contrast with the long-lasting bleeding after a leech bite itself in both species. Calin from the leech Hirudo medicinalis is able, by binding to collagen, to effectively interfere with platelet-collagen interaction, which results in an antithrombotic effect observed in a platelet-rich thrombosis model in hamsters.

scholarly journals Symbiosis of Aeromonas veronii Biovar sobria and Hirudo medicinalis, the Medicinal Leech: a Novel Model for Digestive Tract Associations

1999 ◽  
Vol 67 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Joerg Graf
Keyword(s):  
Digestive Tract ◽  
Bacterial Species ◽  
Bacterial Flora ◽  
Variable Region ◽  
Medicinal Leech ◽  
Hirudo Medicinalis ◽  
Bacterial Growth Rate ◽  
Culturable Bacterium ◽  
Aeromonas Veronii

ABSTRACT Hirudo medicinalis, the medicinal leech, is applied postoperatively in modern medicine. Infections by Aeromonasoccur in up to 20% of patients unless a preemptive antibiotic treatment is administered. The associated infections demonstrate the need for a better understanding of the digestive tract flora ofH. medicinalis. Early studies reported the presence of a single bacterial species in the digestive tract and suggested that these bacteria were endosymbionts contributing to the digestion of blood. In this study, we cultivated bacteria from the digestive tract and characterized them biochemically. The biochemical test results identified the isolates as Aeromonas veronii biovar sobria. This species identification was supported by sequence comparison of a variable region of the genes coding for 16S rRNA. In a colonization assay, a rifampin-resistant derivative of a symbiotic isolate was fed in a blood meal to H. medicinalis. The strain colonized the digestive tract rapidly and reached a concentration similar to that of the native bacterial flora. For the first 12 h, the in vivo doubling time was 1.2 h at 23°C. After 12 h, at a density of 5 × 107 CFU/ml, the increase in viable counts ceased, suggesting a dramatic reduction in the bacterial growth rate. Two human fecal isolates, identified as Aeromonas hydrophila and A. veronii biovar sobria, were also able to colonize the digestive tract. These data demonstrate that the main culturable bacterium in the crop of H. medicinalis isA. veronii biovar sobria and that the medicinal leech can be used as a model for digestive tract association ofAeromonas species.

scholarly journals Identification of Aeromonas veronii Genes Required for Colonization of the Medicinal Leech, Hirudo verbana

2007 ◽  
Vol 189 (19) ◽  
pp. 6763-6772 ◽  
Author(s):  
Adam C. Silver ◽  
Natasha M. Rabinowitz ◽  
Stefan Küffer ◽  
Joerg Graf
Keyword(s):  
Digestive Tract ◽  
Pathogenic Bacteria ◽  
Antimicrobial Property ◽  
Sodium Dodecyl ◽  
Medicinal Leech ◽  
Wild Type ◽  
Aeromonas Veronii ◽  
Hirudo Verbana

ABSTRACT Most digestive tracts contain a complex consortium of beneficial microorganisms, making it challenging to tease apart the molecular interactions between symbiont and host. The digestive tract of Hirudo verbana, the medicinal leech, is an ideal model system because it harbors a simple microbial community in the crop, comprising the genetically amenable Aeromonas veronii and a Rikenella-like bacterium. Signature-tagged mutagenesis (STM) was used to identify genes required for digestive tract colonization. Of 3,850 transposon (Tn) mutants screened, 46 were identified as colonization mutants. Previously we determined that the complement system of the ingested blood remained active inside the crop and prevented serum-sensitive mutants from colonizing. The identification of 26 serum-sensitive mutants indicated a successful screen. The remaining 20 serum-resistant mutants are described in this study and revealed new insights into symbiont-host interactions. An in vivo competition assay compared the colonization levels of the mutants to that of a wild-type competitor. Attenuated colonization mutants were grouped into five classes: surface modification, regulatory, nutritional, host interaction, and unknown function. One STM mutant, JG736, with a Tn insertion in lpp, encoding Braun's lipoprotein, was characterized in detail. This mutant had a >25,000-fold colonization defect relative to colonization by the wild-type strain at 72 h and, in vitro, an increased sensitivity to sodium dodecyl sulfate, suggesting the presence of an additional antimicrobial property in the crop. The classes of genes identified in this study are consistent with findings from previous STM studies involving pathogenic bacteria, suggesting parallel molecular requirements for beneficial and pathogenic host colonization.

Induction and Differentiation of Dental Epithelium in Vivo and in Vitro

1982 ◽  
Vol 40 ◽  
pp. 142-145
Author(s):  
E. J. Kollar
Keyword(s):  
Connective Tissue ◽  
Oral Mucosa ◽  
Basal Lamina ◽  
Functional Derivatives ◽  
Specific Source ◽  
Dental Epithelium ◽  
Connective Tissue Stroma

The differentiation and maintenance of many specialized epithelial structures are dependent on the underlying connective tissue stroma and on an intact basal lamina. These requirements are especially stringent in the development and maintenance of the skin and oral mucosa. The keratinization patterns of thin or thick cornified layers as well as the appearance of specialized functional derivatives such as hair and teeth can be correlated with the specific source of stroma which supports these differentiated expressions.

Ultrastructural Correlations between Clonal Human Tumor Colonies and in Vivo Neoplasms

1982 ◽  
Vol 40 ◽  
pp. 210-211
Author(s):  
M.J. Murphy ◽  
R.R. Price ◽  
J.C. Sloman
Keyword(s):  
Cultured Cells ◽  
Human Tumor ◽  
Cell Type ◽  
Tumor Mass ◽  
Initial Cell ◽  
Cloning Assay ◽  
Human Tumor Cloning ◽  
The Relationship

The in vitro human tumor cloning assay originally described by Salmon and Hamburger has been applied recently to the investigation of differential anti-tumor drug sensitivities over a broad range of human neoplasms. A major problem in the acceptance of this technique has been the question of the relationship between the cultured cells and the original patient tumor, i.e., whether the colonies that develop derive from the neoplasm or from some other cell type within the initial cell population. A study of the ultrastructural morphology of the cultured cells vs. patient tumor has therefore been undertaken to resolve this question. Direct correlation was assured by division of a common tumor mass at surgical resection, one biopsy being fixed for TEM studies, the second being rapidly transported to the laboratory for culture.

Ultrastructure of melanocyte-keratinocyte interactions and pigment transfer in vitro

1978 ◽  
Vol 36 (2) ◽  
pp. 650-651
Author(s):  
Raul I. Garcia ◽  
Evelyn A. Flynn ◽  
George Szabo
Keyword(s):  
Direct Injection ◽  
Skin Pigmentation ◽  
Freeze Fracture ◽  
Pigment Granule ◽  
Time Lapse ◽  
Ultrastructural Level ◽  
Lanthanum Tracer ◽  
A Cell

Skin pigmentation in mammals involves the interaction of epidermal melanocytes and keratinocytes in the structural and functional unit known as the Epidermal Melanin Unit. Melanocytes(M) synthesize melanin within specialized membrane-bound organelles, the melanosome or pigment granule. These are subsequently transferred by way of M dendrites to keratinocytes(K) by a mechanism still to be clearly defined. Three different, though not necessarily mutually exclusive, mechanisms of melanosome transfer have been proposed: cytophagocytosis by K of M dendrite tips containing melanosomes, direct injection of melanosomes into the K cytoplasm through a cell-to-cell pore or communicating channel formed by localized fusion of M and K cell membranes, release of melanosomes into the extracellular space(ECS) by exocytosis followed by K uptake using conventional phagocytosis. Variability in methods of transfer has been noted both in vivo and in vitro and there is evidence in support of each transfer mechanism. We Have previously studied M-K interactions in vitro using time-lapse cinemicrography and in vivo at the ultrastructural level using lanthanum tracer and freeze-fracture.

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