Simvastatin inhibits the oxidation of low-density lipoproteins by activated human monocyte-derived macrophages.

Human monocyte-derived macrophages treated with increasing concentrations of the HMG-CoA reductase inhibitor, simvastatin, showed a dose-dependent decrease in superoxide formation in response to activation by phorbol myristate acetate. As a consequence, they oxidized LDL much less than untreated cells. Addition of exogenous mevalonic acid to simvastatin-treated macrophages restored their ability for superoxide production and for oxidative modification of LDL. These results indicate that simvastatin might prevent atherosclerosis by additional mechanisms besides its hypocholesterolemic activity.

Pseudo type III dyslipoproteinemia is associated with normal fibroblast lipoprotein receptor activity.

Pseudo type III (PT-III) dyslipoproteinemia is characterized by a plasma accumulation of triglyceride-rich lipoproteins (TRL) and their remnants. It mimics type III, but its etiology can not be ascribed to a genetic apo E defect. In order to determine whether PT-III is associated with a genetic lipoprotein receptor abnormality, we have measured (in cultured fibroblasts from affected and nonaffected individuals) the in vitro activity of three lipoprotein receptors which are implicated in the catabolism of TRL, namely the low-density lipoprotein receptor (LDL-R), the lipoprotein receptor-related protein (LRP) and the lipolysis-stimulated receptor (LSR). Specific cell association and degradation of 125I-LDL by LDL-R-upregulated PT-III fibroblasts was not significantly different from that of control cells (103 +/- 10% and 98 +/- 17% of controls; 20 microg/ml 125I-LDL). Specific cell association and degradation of rabbit 125I-beta-VLDL was also not significantly different. LRP activity was assessed by measuring the ability of PT-III and control cells to bind three different LRP ligands: activated alpha2-macroglobulin (alpha2M-MA), lactoferrin and apo E-enriched rabbit beta-VLDL. No significant differences were observed (24.0 +/- 2.1 vs. 23.4 +/- 5.7 fmol/mg for 5 nM of 125I-alpha2M-MA; 4.8 +/- 0.3 vs. 5.2 +/- 1.3 microg/mg for 20 microg/ml of 125I-lactoferrin; 319.4 +/- 51.2 vs. 309.5 +/- 23.2 ng/mg for 5 microg/ml of 125I-beta-VLDL, PT-III vs. control, respectively). LSR activity, as assessed by the cell association or degradation of 125I-LDL by fibroblasts in the presence of 0.5 mM oleate and human leptin, was also not different. No evidence was obtained for deficient cellular recognition of PT-III TRL (d < 1.006 g/ml) by normal human fibroblasts or mouse macrophages. These results suggest that PT-III dyslipoproteinemia is not due to an accumulation in plasma of poorly recognized TRL, nor due to a genetic defect in LDL-R, LRP or LSR.

Cold ischemia-reperfusion injury of the liver. Role of the liver donor nutritional status in rats.

To verify the role of donor nutritional status on the quality of liver preservation after cold storage, we assessed hepatocyte and liver endothelial cell viabilities and functions in an isolated perfused rat liver model. Livers from fed and fasted Wistar rats were isolated and perfused either immediately after liver harvesting or after a 24-hr cold (4 degrees C) preservation in University of Wisconsin solution. Hyaluronic acid (150 ng/ml) and taurocholate (11.5 micrograms/ml) were infused into the reservoir, and their eliminations were assessed to evaluate liver endothelial cell function and hepatocyte function, respectively. Liver viability was estimated by intrahepatic resistance, oxygen consumption, bile secretion, and lactate dehydrogenase release. In addition, cell viabilities were evaluated by trypan blue staining. In fed-rat livers, glycogen content did not differ before or after the cold preservation, although a reduction was observed during the subsequent perfusion period. Liver glycogen content in fed rats was markedly higher than in the fasted rats at each time point studied. In fasted and fed rats, liver viability parameters and hepatocyte function were moderately altered, whereas liver endothelial cell function was markedly impaired after cold preservation. However, feeding had no influence on either hepatocyte or liver endothelial cell functions which were similarly altered in both nutritional conditions. The present data show that the nutritional status of liver donors does not play an important role in the preservation of liver endothelial cells after cold ischemia-reperfusion and, thus, should not affect the overall resistance of livers to hypothermic-ischemic injury.

Effect of calcium antagonists on rat liver during extended cold preservation-reperfusion.

BACKGROUND: Nisoldipine, a calcium antagonist, has been reported to improve the quality of grafted rat livers. We thus assessed the protective effect of two calcium antagonists, nisoldipine and nickel, during extended cold ischemia-reperfusion. METHODS: Rat livers were isolated and perfused before or after 24 hr of cold ischemia in University of Wisconsin solution (4 degrees C) with or without nisoldipine or nickel. Sinusoidal endothelial cell and hepatocyte functions were measured by hyaluronic acid and taurocholate elimination, respectively. RESULTS: Similar alterations in hepatocyte and sinusoidal cell functions were found in all groups after cold ischemia with or without calcium antagonists. In a second set of experiments, liver transplantation was performed in two groups of rats with livers stored under identical conditions with or without nisoldipine. Seven of 12 animals (62.5%) in both groups survived for over 10 days after 24-hr preservation in University of Wisconsin solution. Survival rates were similar in both groups. CONCLUSIONS: Calcium antagonists do not appear to have a direct protective effect on sinusoidal endothelial cell and hepatocyte functions, nor on the overall liver preservation after extended cold preservation-reperfusion.

Oxidative modification of Lp(a) causes changes in the structure and biological properties of apo(a).

We previously showed that oxidative modification converted Lp(a) particles to a form readily recognized by macrophage scavenger receptor(s). This was mediated in part by apo(a) changes indicated by a stronger negative charge protein fragmentation and increased immunoreactivity to monoclonal antibody K07, which also cross-reacted with plasminogen (Pg). The present study demonstrated that the expression of K07 and K09 epitopes of apo(a) increased markedly during time-dependent oxidative modification of Lp(a) by copper ions. Incubation of oxidized Lp(a) with the monocytoid U937 cell line showed that these particles competed more effectively with 125I-type 2 Pg binding to specific cell surface receptors than native Lp(a). This study suggests that oxidative Lp(a) modification causes significant changes in apo(a) conformation, resulting in the enhanced interaction of these particles with macrophage scavenger receptors and Pg binding sites.

[Cardiac rhabdomyomas and aortic valve atresia: an unusual association]. / Rhabdomyomes cardiaques et atrésie valvulaire aortique: une association exceptionnelle.

Necroptic examination of a male newborn baby revealed multiple anomalies of the heart, including multiple cardiac rhabdomyomas, aortic valvular atresia, left cardiac hypoplasia, hypoplasia of proximal aorta and hypertrophy of the right heart. Tuberous sclerosis was not present. In are instances, the association of cardiac rhabdomyomas and other congenital cardiac malformations have been reported but the association documented here has not been, to our knowledge, previously described.

Mitomycin-C nephrotoxicity: a clinico-pathologic study of 17 cases.

The potential nephrotoxicity of Mitomycin-C (MMC) was studied in 17 autopsies from patients treated with this drug, usually in association with other anti-neoplastic agents. Renal functional deterioration was present in seven cases while urinalysis showed an overt proteinuria and hematuria in six and four instances, respectively. Four of these patients also developed a severe microangiopathic hemolytic anemia (MAHA) and thrombopenia. Histological examination did not reveal residual tumor in three of them. However renal lesions similar to those observed in the hemolytic-uremic syndrome (HUS) were associated with glomerular mesangiolytic changes and nuclear atypias in glomerular and tubular cells. Immunofluorescence and ultrastructural studies confirmed these findings. In other patients, variable degrees of cellular atypias and of mesangiolysis were observed. The severity of the glomerular, vascular, and tubular lesions correlated with the total dosage of MMC received. The nephrotoxic potential of MMC seems to be delayed in onset and dose related.

The effect of alcohol-induced hepatomegaly on portal hypertension in cirrhotic rats.

Male Sprague-Dawley rats with CCl4-induced cirrhosis (confirmed by increased collagen content and light microscopy) were fed either ethanol (Group A, n = 9) or isocaloric carbohydrate diet (Group B, n = 8) for 4 weeks. Histologic and hemodynamic measurements were obtained in the awake state before (time 1) and after the 4 weeks of diet (time 2). Portal-systemic shunts were evaluated using radiolabelled microspheres. Liver weight was increased in Group A (16.5 +/- 0.5 vs. 14.2 +/- 0.5 g, mean +/- SE, p less than 0.005) as was the ratio of liver weight over total body weight (3.41 +/- 0.05 vs. 2.86 +/- 0.09%, p less than 0.0001, +19.2%). Hepatocytes surface area was increased in the ethanol group (357 +/- 9 vs. 294 +/- 7 microns 2, p less than 0.0001). In Group B, only 9 +/- 2% of hepatocytes had steatosis as opposed to 69 +/- 3% of centronodular and 34 +/- 3% of perinodular hepatocytes in Group A (p less than 0.001). Portal pressure remained stable in both groups (time 1 (A) 16.9 +/- 0.8, (B) 15.8 +/- 1.1 mmHg, n.s.; time 2 (A) 15.9 +/- 0.7, (B) 15.8 +/- 0.6 mmHg, n.s.). Portal-systemic shunts did not change with time or diet (time 1 (A) 10.6 +/- 3.7%, (B) 4.1 +/- 2.1%, n.s.; time 2 (A) 13.4 +/- 5.9%, (B) 10.8 +/- 4.3%, n.s.).(ABSTRACT TRUNCATED AT 250 WORDS)

Comparative toxicity of adriamycin and adriamycin-DNA in rats.

Adriamycin (ADR) can be linked to DNA without loss of its antitumoral activity while reducing the acute toxicity of free ADR (Deprez--DeCampeneere et al., 1979, 1980). However, the potential chronic toxic effects of both forms of ADR are poorly documented. For such a study, it is necessary to establish the sequence of treatment allowing the administration of a sufficient amount of drugs to induce chronic toxicity and a schedule leading to prolonged survival of animals. In this study, 24 Lewis rats were injected twice a week during four weeks with either free or DNA-linked ADR, and three dose levels were tested: 4, 2 and 1 mg/kg. Our results indicated that the total cumulative dose of ADR should not exceed 8 mg/kg over one month, if prolonged survival is desired. The binding of ADR to DNA seemed also to reduce the acute toxic effects induced by free ADR, in rats. However, such a beneficial effect was not observed when the chronic nephrotoxicity was considered since characteristic renal lesions were observed in all long-term survivors, whatever the dose and the form of ADR received.

Ritanserin decreases portal pressure in conscious and unrestrained cirrhotic rats.

We have recently demonstrated that ritanserin, a serotonin 5-hydroxytryptamine receptor antagonist void of systemic effects, caused a significant reduction of portal pressure in conscious cirrhotic dogs. The mechanism by which ritanserin lowers portal pressure is poorly defined. We investigated the splanchnic and systemic hemodynamic effects of ritanserin (0.63 mg/kg body wt i.v., a dose known to completely inhibit binding of 5-hydroxytryptamine to its receptors), in conscious and unrestrained cirrhotic rats (n = 13). Heparinized catheters were placed into the portal vein, inferior vena cava, aorta, and left ventricle with exit from the neck. Hemodynamic studies were performed 4 h after consciousness was regained. Cardiac output and regional blood flows were measured using radiolabeled microspheres and the reference sample method. Sixty minutes after administration, ritanserin caused a significant reduction of portal pressure (-17%) with minimal changes in portal venous inflow (+3%). Portal vascular resistance decreased significantly (-23%), whereas splanchnic arteriolar resistance was similar before and after ritanserin. A significant increase in mean arterial pressure (+5%) and cardiac output (+22%) was observed. Our results suggest that ritanserin lowers portal pressure through a mechanism separate from portal venous inflow. This effect could be due to changes in intrahepatic or on portocollateral resistances, or both. These findings support the potential use of this new agent in the treatment of portal hypertension.

Decreased in vivo metabolism of drugs in chronic renal failure.

Chronic renal failure (CRF) is associated with a decrease in renal excretion of drugs, but its effects on the liver metabolism of xenobiotics are poorly defined. The objectives of this study were to determine the effects of CRF on hepatic cytochrome P450 (CYP450) and its repercussions on in vivo hepatic metabolism of drugs. Two groups of rats were studied: control paired-fed and CRF. CRF was induced by subtotal nephrectomy. Total CYP450 activity and protein expression of several CYP450 isoforms (CYP1A2, CYP2C11, CYP3A1, CYP3A2) were assessed in liver microsomes. In vivo cytochrome P450 activity was evaluated with breath tests using substrates for different isoenzymes: caffeine (CYP1A2), aminopyrine (CYP2C11), and erythromycin (CYP3A2). Creatinine clearance was reduced by 60% (P <. 01) in rats with CRF. Compared with control paired-fed rats, total CYP450 activity was reduced by 40% in rats with CRF. Protein expression of CYP2C11, CYP3A1, and CYP3A2 was considerably reduced (more than 45%, P <.001) in rats with CRF, whereas the levels of CYP1A2 were unchanged. In rats with CRF, there was a 35% reduction in the aminopyrine (CYP2C11) and the erythromycin (CYP3A2) breath tests compared with control animals (P <.001). The caffeine (CYP1A2) breath tests remained comparable to controls. Creatinine clearance correlated with the aminopyrine and erythromycin breath tests (r(2) = 0.73 and r(2) = 0.81, respectively, P <.001). In conclusion, CRF is associated with a decrease in total liver CYP450 activity in rats (mainly in CYP2C11, CYP3A1, and CYP3A2), which leads to a significant decrease in the metabolism of drugs.

Liver function improvement following increased portal blood flow in cirrhotic rats.

BACKGROUND/AIMS: Liver microcirculation in cirrhosis is characterized by development of intrahepatic shunts and capillarization of sinusoids secondary to cell necrosis and deposition of new collagen, resulting in both decreased drug elimination and increased vascular resistance with portal hypertension. The aim of this study was to examine the effects of increased portal blood flow on hepatic microcirculation and drug elimination in 13 perfused livers from cirrhotic rats. METHODS: Intrahepatic resistance was assessed under basal conditions (21.2 +/- 0.3 mL/min) and 1 hour after doubling the flow (41.6 +/- 1.0 mL/min). A multiple indicator dilution technique was used at both flow rates to measure sinusoidal volume, albumin and sucrose extravascular volumes, and cellular water volume. Hepatic elimination of labeled taurocholate and propranolol was also measured, and the recovery of 15-microns microspheres was used to evaluate large intrahepatic shunts. RESULTS: After doubling the flow, intrahepatic resistance decreased by 31%. Sinusoidal and extravascular volume increased significantly without a change in microsphere recovery. However, there was a marked increase in taurocholate and propranolol elimination by cirrhotic livers. Moreover, during high flow, significant correlations were found between changes in albumin extravascular volume and taurocholate and propranolol elimination. CONCLUSIONS: Increased portal blood flow in cirrhotic rats induces a decrease in intrahepatic resistance without changes in intrahepatic shunting and improves drug elimination by the liver without deleterious effects on hepatocyte viability.

Blood transfusions and survival after colectomy for colorectal cancer.

This study was carried out to determine the effect of perioperative blood transfusions on the survival of patients operated on for colorectal cancers. Cox's regression analysis was applied to 281 patients operated for cure of Dukes' stage A, B or C disease. Other variables studied were age, sex, tumour location, and preoperative hemoglobin, lymphocyte and albumin values. Perioperative deaths, pre- and postoperative immunodepression, neoplasia in situ, nonresections and stage D disease were excluded. It was found that the number of units of blood transfused had a strong influence on the prognosis of patients with colorectal cancer, particularly colonic cancers, but the effect could not be demonstrated when rectal cancers were studied separately, perhaps because of the small number of cases. The mechanism of action of blood transfusions seems to be independent of the other analysed variables. The authors suggest that perioperative blood transfusions may have an immunomodulatory effect in patients with colonic cancer, as already shown in recipients of transfused kidney allografts.

Combined treatment of portal hypertension with ritanserin and propranolol in conscious and unrestrained cirrhotic rats.

We recently reported that ritanserin, a 5-hydroxytryptamine receptor antagonist, induced significant reduction of portal pressure in cirrhotic rats. In this study, we investigated the hemodynamic effects of a combination of propranolol and ritanserin in conscious and unrestrained cirrhotic rats. Heparinized catheters exiting from the neck were placed into the portal vein, inferior vena cava, aorta and left ventricle. Cardiac output and regional blood flows were measured with radiolabeled microspheres and the reference-sample method. Serial hemodynamic studies were performed 4 hr after rats awakened (basal), 1 hr after administration of ritanserin (0.63 mg/kg body wt, intravenously) and after intravenous propranolol infusion (0.33 mg/kg/min for 15 min) in nine cirrhotic rats. Similar measurements were obtained in a control group of eight cirrhotic rats treated with the solvents of ritanserin and propranolol. Ritanserin caused significant reduction of portal pressure (-19%). Portal-venous inflow and splanchnic arteriolar resistances remained unchanged, whereas portal-venous resistances were slightly but significantly lowered (-17%); and ritanserin had no effects on systemic hemodynamics. The addition of propranolol resulted in further reduction of portal pressure (-24%); the final reduction after combined therapy was -38%. Propranolol induced a marked decrease in cardiac output (-31%) and portal-venous inflow (-30%). It also caused a significant increase in splanchnic arteriolar resistance (+39%), but did not magnify the ritanserin-induced decrease of portal-venous resistance. The combined therapy did not modify the mean arterial pressure. Our results show that the effects of ritanserin on portal pressure--probably mediated by a reduction of intrahepatic and/or portocollateral resistances--can be potentiated by propranolol, which lowers the portal-venous inflow.

Unexpected consequences of deletion of the first two repeats of the ligand-binding domain from the low density lipoprotein receptor. Evidence from a human mutation.

Heterozygosity for a 5-kilobase (kb) deletion of the first two ligand-binding repeats (exons 2 and 3) of the low density lipoprotein (LDL) receptor (R) gene (LDL-R delta 5kb) confers familial hypercholesterolemia (FH). The FH phenotype is unexpected based on previous site-directed mutagenesis showing that deletion of exons 2 and 3 resulted in little or no defect in LDL-R activity. In the present study, we took unique advantage of the ability to distinguish the LDL-R delta 5kb from the normal receptor on the basis of size, in order to resolve this apparent discrepancy. Fibroblasts from heterozygotes for the LDL-R delta 5kb displayed 50% of normal capacity to bind LDL and beta-VLDL, apparently due to lower receptor number. Cellular mRNA for the delta 5kb allele was at least as abundant as that for the normal allele. Immunoblotting and cell binding assays with anti-LDL-R antibody IgG-4A4 demonstrated normal synthesis and transport of the delta 5kb receptor. Ligand blotting demonstrated that the delta 5kb receptor displayed minimal or no ability to bind LDL or beta-VLDL. Thus, in contrast to transfected cell lines, in human fibroblasts, the first two cysteine rich repeats of the LDL-R appear functionally necessary. These characteristics of the LDL-R delta 5kb in human fibroblasts explain the in vivo phenotype of carriers.