Absorbable Adams-DeWeese caval clip: an experimental study.

Adams-DeWeese caval clips have been shown to be effective in preventing pulmonary embolism. However, the use of Teflon clips constitutes a permanent solution for this transient risk. We tested an absorbable caval clip made of currently available synthetic biodegradable polymers in five female beagle dogs. The polymer used was PLA 96 containing 96% L lactic acid and 4% D lactic acid. After placement through a laparotomy, clips were routinely inspected and samples of the material were collected at regular intervals between 3 and 19 months postoperatively. The characteristics of absorption of PLA 96 in the retroperitoneal space were the same as those previously described in the literature. The clip retained its shape, rigidity, and effectiveness for 7 months. Complete degradation of the clip took between 18 and 19 months. Absorption did not cause a major inflammatory reaction and had no thrombogenic effect. Given the small number of animals studied, these results must be considered preliminary.

Augmented portal flow in the isolated perfused cirrhotic rat liver: a haemodynamic and morphological study.

1. Isolated perfused cirrhotic rat livers were used to study the effects of an increase in portal perfusion pressure and portal flow on the microcirculation and viability of the hepatocytes. Cirrhosis was induced by CCl4, and Krebs-Ringer bicarbonate buffer solution was used as the perfusate. Portal perfusion pressures were increased incrementally between 25 and 45 cm H2O. The viability of the livers was assessed and histological studies were performed under light and electron microscopy. 2. An increase in portal perfusion pressure induced an increase in hepatic flow in all the experiments (P < 0.05). Hepatic flow was 2.52 ml min-1g-1 of liver (SD 0.67; n = 5) at basal pressure compared with 4.19 ml min-1g-1 of liver (SD 0.93; n = 5) and 5.91 ml min-1g-1 of liver (SD 0.63; n = 5) when pressures were raised to 25 and 45 cmH2O, respectively. Portal perfusion pressure and hepatic flow were correlated (r = 0.908; P < 0.001; n = 30). 3. Production of the enzyme alanine aminotransferase (EC 2.6.1.2) increased significantly from 5.69i.u. ml-1min g-1 of liver (SD 3.62; n = 5) to 23.53i.u. ml-1min g-1 of liver (SD 16.7; n = 5) when the perfusion pressure was raised from baseline to 30 cmH2O. In all the cases the porto-caval gradient of enzyme production was within the normal range. No correlation existed between the release of enzyme and portal perfusion pressures.(ABSTRACT TRUNCATED AT 250 WORDS)

Discordant heart xenografts in the rat. Additional effect of plasma exchange and cyclosporine, cyclophosphamide, or splenectomy in delaying hyperacute rejection.

Natural antidonor antibodies are known to play a prominent role in hyperacute xenograft rejection. The aim of this work was to devise an experimental protocol to prolong the survival time of guinea pig heart xenografts transplanted into rats. A technique of continuous plasma exchange adapted to small animals was used to remove the natural cytotoxic antibodies from the recipient prior to the transplantation. In some experiments, cyclosporine (CsA), cyclophosphamide (CY), or splenectomy were associated with the plasma exchange. In this highly discordant xenogenic donor-recipient combination, the mean graft survival time in nontreated rats was 16 min. When an exchange of 1.5 plasma volume was performed 24 hr before the transplantation, no prolongation of the graft survival time was observed. When CsA, CY, or splenectomy were associated with the plasma exchange, the graft survival time was significantly increased by more than 2500% (up to 418 min with CsA). When used isolately, none of these 3 immunosuppressive methods was able to prolong the graft survival time. Natural cytotoxic antibodies were monitored by a complement-mediated cytotoxicity assay. After a plasma exchange, the titers decreased from 1:16-1:32 to 1:1-1:2. When no immunosuppressive method was associated with the plasma exchange, the antibodies returned to their initial level within the 24 hr that preceded the transplantation, and the graft was rejected as in nontreated animals. When an immunosuppressive method was associated with the plasma exchange, and particularly in the case of CsA, the titers remained low, and the hyperacute rejection was delayed. Therefore, it can be concluded that plasma exchanges, associated with CsA, are an efficient experimental protocol in the rat to increase the survival time of guinea pig heart xenografts. The effect of the treatment is correlated with the decrease in natural cytotoxic antidonor antibodies.

Decreased reticuloendothelial phagocytic capacity in cirrhotic and portacaval shunt rats.

In cirrhosis, the phagocytic function of the reticuloendothelial system (RES) is decreased. In order to investigate the mechanisms of the hepatic reduced phagocytic activity present in cirrhosis, the hepatic and splenic uptake of 51Cr sheep red blood cells (SRBC) and of colloidal carbon was measured in three groups of Sprague-Dawley rats. Group 1 consisted of 42 control rats, group 2 of 36 rats with end-to-side portacaval shunt and group 3 of 24 rats with carbon tetrachloride-induced cirrhosis. The hepatic uptake of 51Cr SRBC and of colloidal carbon was significantly (p less than 0.001) reduced in cirrhotic rats (group 3). Conversely, in rats with a portacaval shunt and a noncirrhotic liver (group 2), the hepatic uptake of 51Cr SRBC was moderately reduced, whereas the colloidal carbon hepatic uptake was not found to be decreased. These results suggest that the decreased RES phagocytic activity observed in cirrhotic rats is only partially due to portacaval shunt and that an intrinsic defective activity of hepatic phagocytic cells is probably present.

[Dimethylnitrosamine hepatic cirrhosis in the rat (author's transl)]. / La cirrhose du rat au diméthylnitrosamine. Essai de corrélation clinique, biologique et anatomo-pathologique en fonction des doses de D.M.N.A. et de l'espèce.

Chronic intoxication with dimethylnitrosamine (D.M.N.A.) in the rat induced an experimental cirrhosis which seems stable in time. The intoxication was done by forcible feeding either with 7 or 8 mg/kg of D.M.N.A., three consecutive days a week, for 9 weeks. Chronical intoxication resulted in 50% of hepatic cirrhosis in the 7 mg/kg group and 63% in the 8 mg/kg group. --The diagnostic of hepatic cirrhosis was done by pathological study on the left lobe. --In all cirrhotic rats, verified by histology, biological test were disturbed in a significant way, compared to untreated rats, but not to non cirrhotic intoxicated rats. There was no correlation between pathological anatomy and biology. --Cirrhosis persists after the intoxication but survival duration is much shorter in the group intoxicated with 8 mg/kg of D.M.N.A. --There was no difference in the constitution of cirrhosis between Wistar and Sprague Dawley strains. Therefore the best procedure to induce cirrhosis in rats is chronical intoxication by administration of 7 mg/kg of D.M.N.A. during 3 consecutive days a week for 9 weeks. Pathological study are the only reliable tests to determine the constitution of cirrhosis.