U Bagge

A technical and biomechanical comparison between two types of microvascular anastomoses. An experimental study in rats.

The microvascular sleeve anastomosis, where one vessel is inserted into the other, was compared with the conventional end to end anastomosis. In an experimental study in rat femoral arteries 42 anastomoses of each kind were examined. Operating time, patency rates, flow rates and strength of the anastomoses were recorded at various postoperative time intervals. It is concluded that the sleeve anastomosis is quicker to perform and that the two types of anastomoses in biomechanical respects are similar. Flow rates are slightly decreased immediately postoperatively in the sleeve anastomosis but this is of a temporary nature.

Differences in lodgement of tumour cells in muscle and liver

Differences in the lodgement of circulating tumour cells in various organs are considered an important factor in metastatic organ selection. The present vital microscopic studies show that the pattern of intravascular arrest of tumour cells in muscle after intra-arterial injection is similar to that observed earlier, in the liver, after intraportal injection. However, parallel isotope studies on the lodgement process (at 5 min and 3 h after injection) showed that the tumour cells trapped in the muscle microvasculature were destroyed at a higher rate than in the liver. Tumour cells kept in test tubes, and thus not being subjected to the shearing forces of the circulation, had a higher survival rate than cells trapped in the muscle. The results indicate that stronger retardation forces acting on the tumour cells in muscle (arterial dissemination) than in the liver (venous dissemination) may be one mechanism behind the increased tumour cell destruction in muscle.

Inhibition of leukocyte phagocytosis by serotonin and its possible role in tumor cell destruction

Intraportal tumour cell (TC) injection activates platelets which release serotonin (5-HT). Thrombocytopenia or 5-HT blockade decrease the hepatic lodgement of the injected TCs. A hypothetical explanation of this is 5-HT inhibition of TC killing by phagocytes (e.g. leukocytes and Kupffer cells). In this study, leukocyte phagocytosis was analysed by a chemiluminescence technique at different 5-HT concentrations. Significant inhibition of phagocytosis occurred at 5-HT concentrations of 10(-4) M to 10(-8) M, with maximum inhibition at 10(-4) M. Comparable concentrations of 5-HT may be found locally in the liver during TC infusion, supporting the hypothesis that 5-HT has an inhibitory effect on phagocyte-mediated TC killing.

Proliferative Synovitis in Rabbit Knee Joints Induced by Antigen and Preformed Immune Complexes

Knee joints of non-immunized rabbits were repeatedly injected with bovine serum albumin (BSA) and preformed BSA-anti-BSA immune complexes which had differing precipitation profiles and abilities to activate complement. Ten days after the last of six injections the antibody and lymphoproliferative responses to BSA were analysed and correlated to the degree of arthritis. Joint swelling, increased numbers of joint fluid leukocytes and morphological changes typical of proliferative synovitis were found only in those rabbits injected with a large dose of antigen or with immune complexes prepared in antigen excess of poor precipitation and complement-activating properties in vitro. The degree of arthritis correlated with the development of humoral and lymphoproliferative immune responses to BSA.

Joint inflammation in rabbits induced by preformed immune complexes

The rabbit knee joint was used to evaluate the inflammatory properties of immune complexes with different contents of antigen. Immune complexes made in vitro with antiserum from hyperimmunized rabbits and bovine serum albumin as antigen were injected into the joints. The reactivity of the individual animal was established by injection of normal rabbit serum into the contralateral joint. The number of leukocytes washed out from the joints at fixed intervals was used as a measure of the inflammatory properties of the immune complexes. With immune complexes formed at antigen excess the highest numbers of leukocytes, with a predominance of granulocytes, were found after 6 h of exposure. However, these complexes gave only weak complement activation in vitro, measured with a hemolysis assay. Complexes formed at optimal precipitation proportions gave high complement activation in vitro but only a small number of leukocytes in the joints at 6 h exposure. This finding may be explained by a rapid phagocytosis of the latter complexes while complexes formed at antigen excess are not readily phagocytized. This hypothesis is supported by the observation that higher leukocyte counts were found after shorter exposure times to complexes formed at optimal precipitation proportions than after exposure to complexes with antigen excess.

Inhibitory effect of honey bee venom on immune complex mediated leukocyte migration into rabbit knee-joints

The anti-inflammatory effect of purified honey bee venom (HBV) was studied using a recently described animal model in which preformed immune complexes were injected into rabbit knee-joints. As little as a single injection of 1.2 μg HBV/kg body weight subcutaneously significantly reduced the immune complex induced joint inflammation as measured by reduction in leukocyte counts in the joint fluid. This decrease was obvious 3 and 6 but not 9 hours after induction of the inflammation.There was no significant effect on leukocyte random migration, chemotactic responsiveness or phagocytosis, indicating that HBV did not interfere with normal phagocyte motility and ingestion. The modifying effects by HBV on the inflammatory response to immune complexesin vivo is most likely due to interference with other components of the inflammatory response.

Acute synovitis induced by preformed immune complexes

The morphology of acute immune complex (IC) elicited synovitis in rabbit knee joints was studied, as well as IC-induced leukocyte activation in vivo and in vitro. Acute synovitis was induced by intra-articular injection of in vitro preformed, complement activating bovine serum albumin (BSA)-anti-BSA IC. Within 30 min, migration of polymorphonuclear granulocytes (PMNGs) was observed. Scanning electron microscopy showed that adhering, apparently activated leukocytes were attached to the synovial lining, often forming clusters. Phagocytosis of IC was evident, as immunoglobulins were detected within the leukocyte cytoplasm by the direct immunofluorescence technique. At the peak accumulation of PMNGs, focal erosions of the synovial lining were observed. Later, monocytes and macrophages appeared and degenerated PMNGs were found, sometimes within the cytoplasm of large macrophages. Chemiluminescence experiments showed a maximum in vitro activation of leukocytes by complement activating IC formed near optimal precipitation proportions and in slight antigen excess, whereas IC in large antigen excess gave a smaller and later response.

The Influence of Locally Deposited Fibrin on the Biomechanical Properties of Developing Granulation Tissue in Rats

A recently developed method for the occlusion of fistulas with a fibrin clot has stimulated studies concerning the effects of deposited fibrin on the formation of granulation tissue (g.t.). In this study the influence of artificially implanted fibrin on the biomechanical properties of developing g.t. was investigated in rats. Perforated Teflon cylinders either empty or fibrin filled, were implanted subcutaneously for two weeks. The g.t. from fibrin filled cylinders was found to adhere significantly better to the cylinder walls which is an important property in the case of fistula closure with fibrin. Mechanical testing, however, showed that the maximum load and the maximum strain were significantly higher in cylinders implanted empty. However, the collagen concentration was no higher in cylinders implanted empty suggesting that in the newly formed g.t. studied, factors other than the collagen concentration determined the strength of the tissue.

The Effect of Pressure and its Duration on Microcirculation and Healing of Skin Flaps1: An Experimental Study in Rabbits

An experimental model to study the effects of temperature, ischemia and pressure on microcirculation and wound healing in rabbit skin flaps is described. An island skin flap is inserted into a plexiglass chamber and a transverse segment at the middle of the flap is compressed with a plastic cuff. When the cuff is inflated the flap is divided into three segments, one used as a control, one being subjected to pressure and ischemia and one being ischemic only. The method has been tested on two groups of rabbits; in one group a pressure of 200 mmHg was applied for 2 hours while in the other the same pressure was applied for 4 hours. The temperature was kept constant at 36°C in both groups. The microcirculation was observed with a vital microscope in all segments during and after release of the pressure. After the acute experiments the flaps were resutured. Eight days later the influence of the pressure/ischemia was assessed using microangiography and by checking wound healing of the different flap segments. T...

Determination of wound strength for quantitation of skin damage after pressure ischemia. An experimental study in rabbits

Rabbits skin folds were placed in plexiglass chambers enabling control of the skin fold temperature during cuff compression (200 mmHg) for 4 hours. In 10 animals the skin folds were kept at 36 degrees C - in another 10 animals the skin fold temperature was lowered to 10 degrees C. To quantitate the skin injury caused by the pressure ischemia a standardized wound was made, and immediately closed, after release of pressure. Control wounds were made in normal skin. Seven days later the mechanical strength of the wounds was tested by determination of breaking load. There was no significant difference in breaking load between the wounds made in normal skin and in the skin folds kept at 10 degrees C, whereas the breaking loads was significantly decreased in the wounds made in skin folds kept at 36 degrees C, i.e. normal skin temperature, compared with the controls. Thus, the results show that cooling may preserve the reparative capacity in skin subjected to pressure ischemia. It is assumed that this effect is related to a lowered cell metabolism during the ischemia. It may also be concluded that the pressure (mechanical) injury, being the same in both temperature groups, is less important than the ischemic injury.