Biochemical characterization of a new melanoma model--the minipig MeLiM strain.

Hereditary minipig melanomas, which have many histopathological and other features in common with their human counterparts, have recently become preferred melanoma models. The MeLiM (Melanoma-bearing Libĕchov Minipig) strain was selected by partial inbreeding. A high tumour incidence and malignant behaviour on the one hand together with the occurrence of spontaneous regression and high susceptibility to the devitalization technique as a new strategy in melanoma therapy, make the MeLiM strain a superior melanoma model to other hereditary swine melanomas.

Hereditary melanoblastoma in miniature pigs and its successful therapy by devitalization technique.

Applying selective breeding for 10 years we established the MeLiM (Melanoblastoma-bearing Libechov Minipigs) strain. Melanoblastoma (MB) in this strain shows a hereditary occurrence. Cutaneous tumours are usually nodular, multiple and distributed on various parts of body.

[Melanoblastoma in laboratory minipigs: a model for studying human malignant melanoma].

Human malignant melanoma is a progressively growing tumour mostly with a fatal prognosis during short time. Its frequency has doubled in some states of the USA during the last few years. Surgical treatment, which is still generally used, has very low efficiency due to the numerous metastases in different organs.

[Use of the tourniquet in gastrointestinal surgery].

Experimentally induced total or partial intestinal obstructions (ileus) in pigs were surgically treated by means of a tourniquet technique. A lace used in obstetrics for ligation of umbilicus served as the tourniquet. The lace was protracted around an intestine, both ends were threaded through 7-10 cm long rubber tube and fixed by Pean's forceps.

Experimental devascularization (devitalization) of the rectum and sigmoideum.

In 6 laboratory pigs, devascularization (devitalization) of the rectum and the adjacent part of the sigmoideum was carried out by the vasa rectalia cranialia et media ligatures with simultaneous aboral closure of the rectum at the base of the lesser pelvis and oral closure at the borderline between the rectum and the sigmoideum. The devascularized rectum was not removed but left in situ. Terminal colostomy was established.

A technique of the segmental devitalization of kidneys in experiment.

With the help of partially overlapping parenchymatous sutures, different renal segments were devitalized. After 8 weeks, a fibrous conversion occurred in devitalized part of the kidney. For the orientation during establishing the sutures, a topographic schematic diagram was used, which is simple and quite satisfactory for the use in practice.

The devitalization of the stomach by a devascularization technique.

Different parts of the stomach in healthy animals (pigs) were devitalized (devascularized) by eliminating the blood supply and left in situ. In model experiments, parts of the stomach were chosen for the devitalization with respect to most frequent location of carcinomas. The operation technique consisted of a complete ligature of perigastric vessels, bling enclosure of the cranial part of the duodenum with two ligatures with a possible application of a seromuscular suture and transverse cutting of the oral part of the stomach and its enclosing by a suture with a partial invagination of the wall.

Changes of clinical biochemical values after bilateral nephrectomy and allotransplantation of the kidney in pigs.

In a series of 10 healthy pigs, the normal ranges of the following biochemical parameters in blood serum were assessed: creatinine, urea, mineralogram (Na, K, Cl), uric acid, bilirubin, total protein, cholesterol, blood lipid level, thymol turbidity reaction and activities of alkaline phosphatase, alpha-amylase and transaminases. The changes of these values were followed up in two pigs after bilateral nephrectomy and in 18 pigs subjected to orthotopic allotransplantation of the kidneys. The examination confirmed that creatinine and urea are the most important values with a prognostic impact.

Morphology of regressive changes in the kidney following experimental ischaemia.

Total or partial renal ischaemia was studied in rats and pigs in a series of experiments, after total devascularization (ligature of renal vessels and ureter); ligature of isolated renal artery; experimental embolization of renal artery by non-resorbable material; devascularization of a specific renal segment by deep, strangulating sutures. Morphological studies showed that the resulting necrotization is represented most frequently by coagulation necrosis, less frequently by colliquating necrosis. Occlusion of the renal artery by embolization or ligature leads only to partial necrotization or atrophy.

[Intestinal invagination in pigs].

The invaginations of small intestine are being described which represent one of possible causes of intestinal ileus. In connection with multiple invaginations, a case of two intussusceptions is being mentioned, in which the peaks of invaginates are directed towards each other. At the same time four theoretically possible double invaginations are presented as well as a proposal for their distinction and indication.

Experimental elimination of various intestinal segments by means of devascularization (devitalization).

Segments of the small and large intestine, of varying lengths (10-180 cm), were devascularized by simultaneously ligating the mesenteric arteries and veins. When the circulation had been cut off, the ends of the devascularized segment were both ligated, continuity of intestinal passage was renewed by forming an anastomosis and the isolated segment was left in situ, together with its contents. Contrary to accepted views, no changes leading to death (necrosis and peritonitis) occurred, but the devascularized tissue was progressively destroyed and reconstructed until, after four weeks, all that was left was a minute fibrous residue.

[Small and large intestine devascularization (devitalization) and potentials in the therapeutic use of this operative method].

The experimental findings with devitalization of various intestinal segments by means of devascularization showed that the isolated segments left in peritoneal cavity (together with their contents) were gradually destroyed and changed into a slight fibrous residue. The retaining of the up to 180 cm long segment did not endanger the life of experimental animals. This experience was used in the surgical treatment of inoperable tumours in left half of large intestine and in rectosigmoideum.

Subcutaneous transposition of a kidney (an experimental study in the rat).

To make the kidney better available for requirements of experimental practice, the authors evolved a technique for subcutaneous transposition of a kidney in the rat. If saline with antibiotics (PEN, STM) is infused intraperitoneally during the operation, the technique gives very good results.

The technique of ureterocystoneostomy in experimental renal orthotopic allotransplantation in the pig.

Experimental orthotopic renal allotransplantation performed in pigs allowed us to verify some techniques of ureterocystoneostomies from the urological point of view. For the reconstruction of the urinary pathways we employed anastomosis in 7 cases, and implantation of the ureter into the bladder in 3 cases, using the antireflux technique in 9 animals and the now common ureteral implantation with the terminal segment of the ureter placed in tunnel serosa in 24 animals. The results of our modification confirm the importance of peritoneal plasty of the terminal ureteral segment for the prevention of urinary fistulas.

Immunogenetic studies in semi-inbred pigs.

Seventy-six siblings from 11 semi-inbred families of Landrace pigs (inbreeding coefficient 0.70-0.82) were used for transplantation of skin and renal allografts.