Activity and tissue-specific expression of lipases and tumor-necrosis factor alpha in lean and obese cats.

Post-heparin plasma activity of lipoprotein lipase (LPL) and hepatic lipase (HL), and fat and muscle activity of LPL were measured in neutered lean and obese cats. Lipoprotein lipase, hormone-sensitive lipase (HSL), and tumor necrosis factor a (TNF) mRNA were measured in muscle and fat tissue with real-time PCR using primers for feline LPL, HSL, and TNF. Lipoprotein lipase plasma and fat activity and fat mRNA levels were significantly lower (50, 80, and 50%, respectively) in obese cats than lean cats, whereas the muscle/fat ratio of LPL was significantly higher in obese compared to lean cats. The activity of HL was not different between the groups. Hormone-sensitive lipase mRNA levels were significantly higher in obese than lean cats. The level of fat TNF also was significantly higher in obese cats than in lean cats, whereas the level in muscle was not different. The lower LPL activity and mRNA expression in fat and the higher LPL and HSL mRNA expression in muscle in obese cats compared to lean cats expectedly favor a redistribution of fatty acids from fat to muscle tissue where they can be deposited or used for energy in times of need. Tumor necrosis factor alpha may regulate this repartitioning process through suppression of adipocyte LPL.

Stability studies of ubiquinol in plasma.

BACKGROUND: Ubiquinol is a sensitive redox marker in the first line of the antioxidative defence mechanism and is increasingly being measured in oxidation studies. Because of its apparent instability during storage and processing, we compared various storage conditions. METHOD: Blood was collected from three volunteers into tubes containing EDTA; it was then separated at 4 degrees C and cryopreserved with saccharose (final concentration 6 g/L). Aliquots were stored with or without glutathione or butylated hydroxytoluene at -20 degrees C and -80 degrees C. RESULTS AND CONCLUSION: Ubiquinol in samples stored at -20 degrees C was not stable; however, it was stable when stored at -80 degrees C, even without addition of antioxidant. By contrast, alpha-tocopherol was stable under all conditions studied.

Effects of peritoneal dialysis with an overnight icodextrin dwell on parameters of glucose and lipid metabolism.

OBJECTIVE: To examine whether a reduced daily glucose load by overnight application of the less-absorbed glucose polymer icodextrin would have favorable effects on lipid profiles of continuous ambulatory peritoneal dialysis (CAPD) patients. STUDY DESIGN: Randomized crossover study with two subsequent periods of 6 weeks. SETTING: Home PD unit of a secondary-care hospital. PATIENTS: Twenty-one nondiabetic CAPD patients (15 male, 6 female; mean age 50.3+/-11.8 years). INTERVENTION: Participants were randomly assigned to receive an overnight dwell with either standard glucose solution or with a 7.5% icodextrin-containing solution. MAIN OUTCOME MEASURES: Relation between reduction in the total amount of intraperitoneal infused glucose and parameters of glucose (plasma glucose, insulin, and HbA1C) and lipid metabolism [free fatty acids, plasma lipids, lipoproteins, and low density lipoprotein (LDL) subfraction profile]. RESULTS: After the icodextrin dwells, a reduction of plasma total cholesterol (from 5.43+/-0.85 to 4.86+/-0.70 mmol/L, p < 0.001) and LDL cholesterol (from 3.38+/-0.87 to 2.93+/-0.73 mmol/L, p = 0.001) was observed. Also, high density lipoprotein (HDL) cholesterol (from 0.95+/-0.27 to 0.90+/-0.24 mmol/L, p = 0.029) was reduced, but the plasma total cholesterol-to-HDL ratio remained similar. Plasma free fatty acids and triglyceride levels tended to decrease (from 0.16+/-0.10 to 0.13+/-0.08 mmol/L, p= 0.06, and from 2.14+/-1.96 to 1.92+/-1.03 mmol/L, respectively). Evaluation of LDL subfraction profiles after ultracentrifugation showed a more buoyant LDL subfraction profile with fewer dense LDL particles in 6 patients and no changes in 14 patients after icodextrin. The effects on lipids were not accompanied by a decrease in fasting plasma glucose (from 5.76+/-1.29 to 5.86+/-0.80 mmol/L) or insulin levels (from 19.5+/-14.4 to 20.3+/-13.0 mU/L). CONCLUSION: These results suggest a beneficial effect on lipid profiles of CAPD patients with the use of an overnight dwell with icodextrin.

Effects of alpha-tocopherol on superoxide production and plasma intercellular adhesion molecule-1 and antibodies to oxidized LDL in chronic smokers.

Antioxidants have been postulated to exert beneficial effects in atherosclerosis. Atherosclerosis is associated with raised plasma levels of soluble intercellular adhesion molecule-1 (sICAM-1) and autoantibodies against oxidized low-density lipoprotein (oxLDL). It is not known whether antioxidants affect these plasma factors in chronic smokers. In a randomized double-blind placebo-controlled study involving 128 male normolipidemic chronic smokers the effect of a 2-year alpha-tocopherol treatment (400 IU dL-alpha-tocopherol daily) on plasma levels of sICAM-1 and autoantibodies against oxLDL was evaluated. In addition, we monitored production of superoxide by leukocytes ex vivo. It was found that compared to nonsmokers (n = 33) plasma levels of IgG but not IgM autoantibodies against oxLDL and concentrations of sICAM-1 in smokers were significantly elevated (30 and 42%, respectively). After supplementation with alpha-tocopherol concentration of TBARS in plasma and in vitro oxidizability of LDL had decreased, but autoantibodies and sICAM-1 had not changed. Production of superoxide was not different between alpha-tocopherol- and placebo-treated smokers. It is concluded that in chronic smokers, long-term treatment with alpha-tocopherol does not normalize the raised levels of sICAM-1 and autoantibodies against oxLDL, both risk factors for initiation or progression of cardiovascular disease, despite a decrease in in vitro oxidizability of LDL.

Comparison of the antiatherosclerotic effect of tibolone with that of estradiol and ethinyl estradiol in cholesterol-fed, ovariectomized rabbits.

OBJECTIVE: Tibolone is a synthetic steroid with tissue-specific estrogenic, progestogenic, and androgenic properties. The drug relieves climacteric symptoms and prevents osteoporosis but does not stimulate the endometrium. We have previously shown that in laboratory animals tibolone inhibits the atherogenesis induced by a high-cholesterol diet. Therefore, we compared the antiatherosclerotic effect of oral tibolone at different dose levels with that of oral 17beta-estradiol (E2) and ethinyl estradiol (EE). DESIGN: Atherosclerotic lesion formation (increase in vessel wall cholesterol deposition and fatty streak formation) was measured in ovariectomized rabbits after 20 weeks on an atherogenic diet (fed daily 80 g of a rabbit chow containing 0.4% cholesterol, 3.75% peanut oil, and 3.75% coconut oil) in eight groups: group 1, placebo (n = 35); group 2, control (n = 34) received normal rabbit chow; group 3, E2 group (E2 4 mg, n = 12); group 4, EE group (EE 60 microg, n = 10); and groups 5-8, tibolone (6 mg, n = 12; 2 mg, n = 13; 0.6 mg, n = 25; and 0.15 mg, n = 11, respectively). During the study, blood samples were obtained for the evaluation of plasma triglycerides, cholesterol, lipoproteins, and glutamate pyruvate transaminase. After 20 weeks, the animals were killed, and cholesterol concentration and the formation of fatty streaks in the wall of the aortic arch were evaluated. RESULTS: In the placebo group, the atherogenic diet induced a mean increase in total plasma cholesterol concentration from 1.1+/-0.1 mmol/L (control group) to 34.1+/-1.8 mmol/L (mean +/- SE). This resulted in an accumulation of cholesterol in the aortic arch from 48+/-4 (control group) to 608+/-44 nmol/mg protein and in the formation of fatty streaks (41.8+/-3.2% of the surface of the aortic arch was covered with fatty streaks). Tibolone had strong dose-dependent antiatherosclerotic effects. It reduced the accumulation of cholesterol in the aortic arch at doses of 6 to 0.15 mg by 99, 97, 87, and 57% and the formation of fatty streaks by 98, 97, 81, and 38%, respectively. E2 had only a marginal antiatherosclerotic effect, whereas EE showed an effect comparable to that of tibolone at doses of 2 to 0.6 mg. With EE, the accumulation of cholesterol in the vessel wall was reduced by 93% and the formation of fatty streaks by 73%. Mean plasma cholesterol concentrations were also reduced by tibolone (64, 70, 61, and 47%) and EE (57%). This reduction was mainly mediated via a reduction in beta-very-low-density lipoprotein cholesterol. Analysis, however, indicated that the observed antiatherosclerotic effects of tibolone and EE, at least partly, are due to a direct effect on the vessel wall and independent of the changes in plasma cholesterol. At equipotent antiatherosclerotic doses, EE showed a stronger uterotropic effect (measured as the increase in uterine weight) than tibolone. EE increased uterine weight from 0.57 g/kg body weight (BW) (control group) to 3.5 g/kg BW; tibolone at doses of 6, 2, 0.6, and 0.15 mg increased uterine weight to 2.5, 2.8, 2.2, and 1.3 g/kg BW, respectively. CONCLUSION: Tibolone can protect the arterial vessel wall against atherosclerotic lesions induced by a hypercholesterolemic diet. However, it has much less estrogenic effects on the uterus compared with EE at equipotent doses, indicating tissue selectivity for tibolone. The clinical implications of these findings require investigation.

Effect of plant sterol-enriched margarine on plasma lipids and sterols in subjects heterozygous for phytosterolaemia.

OBJECTIVE: Margarine with added plant sterols lowers plasma cholesterol levels. It is of importance to know whether these margarines can be used safely in carriers of a hereditary disorder with increased absorption of plant sterols. DESIGN: In an open feeding study of 8 weeks with a 2-week run-in period and 2 final weeks as a washout period on control margarine (0.3% plant sterols), two obligate heterozygous parents of a patient with classical sitosterolaemia were subjected for 4 weeks to a diet containing margarine enriched with plant sterols (8%). Fasting blood samples were taken weekly. Primary outcomes were plasma lipid and lipoprotein levels and plant sterol levels. RESULTS: Both parents were hyperlipidaemic. Total plasma cholesterol levels were decreased by 11 and 12%, respectively, after 4 weeks of the consumption of 40 g day(-1) of plant sterol-enriched margarine. This was mainly due to changes in LDL-cholesterol, whereas the other lipoproteins, including lipoprotein(a), were unaffected. Total plant sterol levels increased maximally 139% from 0.31 to 0.82% of total sterols in the father, and maximally 83% from 0.32 to 0.66% of total sterols in the mother. CONCLUSION: An intake of around 3 g day(-1) of plant sterols by subjects heterozygous for phytosterolaemia increased campesterol or sitosterol levels in blood to similar levels as found in normal subjects. In addition, plasma cholesterol levels were reduced to the same extent as in normal or hypercholesterolaemic individuals.

The coffee diterpene cafestol increases plasma triacylglycerol by increasing the production rate of large VLDL apolipoprotein B in healthy normolipidemic subjects.

BACKGROUND: Cafestol is a diterpene in unfiltered coffee that raises plasma triacylglycerol in humans. OBJECTIVE: We studied whether cafestol increases plasma triacylglycerol by increasing the production rate or by decreasing the fractional catabolic rate of VLDL(1) [Svedberg flotation unit (S(f)) 60-400] apolipoprotein (apo) B. In addition, we studied the effect of cafestol on the composition of VLDL(1) and VLDL(2) (S(f) 20-60). DESIGN: Eight healthy normolipidemic men were administered a daily dose of 75 mg cafestol for 2 wk. A bolus injection of 7 mg L-[5,5,5-(2)H(3)]leucine/kg body wt was given after a baseline period with no cafestol and again after treatment with cafestol. We derived kinetic constants to describe the metabolism of VLDL(1) apo B by using a multicompartmental model. RESULTS: Cafestol significantly increased plasma triacylglycerol by 31% or 0.32 mmol/L (95% CI: 0.03, 0.61); the increase was due mainly to a nonsignificant rise in VLDL(1) triacylglycerol of 57% or 0.23 mmol/L (95% CI: -0.02, 0.48). Cafestol significantly increased the mean rate of VLDL(1) apo B production by 80% or 755 mg/d (95% CI: 0.2, 5353), whereas it did not significantly change the mean fractional catabolic rate of VLDL(1) apo B (mean increase of 3 pools/d; 95% CI: -4, 10]). Cafestol did not change the composition of VLDL(1). A significant increase in the ratio of VLDL(2) cholesteryl ester to triacylglycerol indicates that VLDL(2) became enriched with cholesteryl esters at the cost of triacylglycerol. CONCLUSION: Cafestol increases plasma triacylglycerol by increasing the production rate of VLDL(1) apo B, probably via increased assembly of VLDL(1) in the liver.

Reduced adrenal response to bacterial lipopolysaccharide in interleukin-6-deficient mice.

Administration of bacterial lipopolysaccharide (LPS) in rodents induces the release of pro-inflammatory cytokines [tumor necrosis factor (TNF), interleukin (IL)-1, IL-6] and of ACTH and corticosterone. IL-6 is probably an important cytokine in the interaction between the immune system and the hypothalamus-pituitary-adrenal (HPA) axis, but so far the role of IL-6 in lipopolysaccharide (LPS)-induced HPA activation has not been established unequivocally. We examined the effects of intraperitoneal administration of LPS (range 0.25-2000 pg/mouse) on plasma corticosterone, TNFalpha and IL-1alpha levels in IL-6-deficient (IL-6 -/-) and wildtype control (IL-6 +/+) mice. Plasma corticosterone levels increased within one hour in both mouse strains. The corticosterone response was significantly reduced in IL-6 -/- mice, but no differences in TNFalpha or in IL-1alpha plasma levels were found between the two strains. Next, we studied the involvement of IL-1alpha or TNFalpha in the responses to LPS in IL-6 -/- and IL-6 +/+ mice by infusion of recombinant human IL-1 receptor antagonist (IL-1ra), or by injection of anti-TNFalpha antibodies. Pretreatment with IL-1ra or with anti-TNFalpha did not affect the corticosterone response to LPS, neither in IL-6 -/-, nor in IL-6 +/+ mice. Our data suggest that in the stimulation of the HPA axis by LPS in mice blockade of either IL-1alpha or TNFalpha may be compensated for by other mediators. The reduced adrenal response after LPS administration found in IL-6 -/- mice indicates a distinct role for IL-6 in the activation of the HPA axis by LPS.

Smoking or its cessation does not alter the susceptibility to in vitro LDL oxidation.

BACKGROUND: Enhanced induction of low density lipoprotein (LDL) oxidation may play a role in the increased cardiovascular risk in smokers. We determined LDL oxidisability in vitro in non-smokers, smokers and in subjects after smoking cessation. PATIENTS AND METHODS: Plasma lipids and copper induced LDL oxidation in vitro were measured in 31 persistent smokers, 47 smokers who tried to stop smoking and 25 non-smokers. In the smoking cessation group, blood was collected before then 1, 3, 6 and 12 months after smoking cessation, and in the persistent smoking and non-smoking groups at baseline and after 12 months. Plasma thiobarbituric acid reactive substances (TBARS) were measured 3 times (at baseline then after 1 and 3 months) in all subjects who refrained from smoking (controlled by urinary cotinine concentrations) for at least 3 months. RESULTS: At baseline, no differences in mean age, body mass index and lipid profiles between groups were present. Seventeen subjects of the smoking cessation group (36%) managed to quit during 12 months. Smoking cessation was associated with an increase in mean weight (P

The effect of concentrated n-3 fatty acids versus gemfibrozil on plasma lipoproteins, low density lipoprotein heterogeneity and oxidizability in patients with hypertriglyceridemia.

We evaluated in a double-blind randomized trial with a double-dummy design in 28 patients with primary hypertriglyceridemia, the effect of gemfibrozil (1200 mg/day) versus Omacor (4 g/day), a drug containing the n-3 fatty acids eicosapentaenoic (EPA) and docosahexaenoic acid (DHA), on lipid and lipoprotein levels, low density lipoprotein (LDL) subfraction profile and LDL oxidizability. Both Omacor and gemfibrozil therapy resulted in a similar significant decrease in serum triglyceride (TG), very low density lipoprotein (VLDL) triglyceride and VLDL cholesterol concentrations and an increase in high density lipoprotein (HDL) and LDL cholesterol concentrations. The increase in LDL cholesterol was due to a significant increase in cholesterol content of the relatively buoyant LDL subfractions LDL1, LDL2 and LDL3, whereas the relative contribution of the dense LDL subfractions LDL4 and LDL5 to total LDL tended to decrease. So, both therapies resulted in a more buoyant LDL subfraction profile, reflected by a significant increase of the value of parameter K (+10.3% on Omacor vs. +26.5% on gemfibrozil therapy, gemfibrozil vs Omacor P>0.05). Cu(2+)-induced oxidation of LDL was measured by continuous monitoring of conjugated dienes. After 12 weeks of Omacor treatment LDL appeared more prone to oxidative modification in vitro than LDL after gemfibrozil treatment, as measured by the significantly decreased lag time, preceding the onset of the lipid peroxidation. In both groups the rate of oxidation did not change with therapy. The amount of dienes formed during oxidation increased significantly on Omacor treatment, but not on gemfibrozil treatment. Plasma thiobarbituric acid reactive substances were higher after Omacor and lower after gemfibrozil treatment, although not significantly. We conclude that both Omacor and gemfibrozil have favorable effects on lipid and lipoprotein concentrations and the LDL subfraction profile. However, Omacor increased the susceptibility of LDL to oxidation, whereas gemfibrozil did not affect the resistance of LDL to oxidative modification in vitro. The clinical relevance of these changes remains to be established in the light of other postulated favorable effects of n-3 fatty acids on the course of cardiovascular disease.

Oxidized low-density lipoprotein induces calcium influx in polymorphonuclear leukocytes.

Polymorphonuclear leukocytes (PMN) have been suggested to play a role in atherosclerosis, but intracellular signaling after stimulation with oxidized low-density lipoprotein (LDL) is unknown. We investigated mechanistic aspects of oxidized LDL-induced superoxide production by human PMN, with special emphasis on intracellular Ca(2+) concentration ([Ca(2+)](i)). Oxidized LDL, but not native LDL, evoked an early but sustained increase in [Ca(2+)](i) and a delayed production of superoxide. The increase in [Ca(2+)](i) could be reduced by fucoidan and completely prevented by U73122, suggesting involvement of the scavenger receptor and coupling to the phospholipase C signal transduction pathway. Furthermore, we provide evidence that the increase in [Ca(2+)](i) partly results from protein kinase C-dependent Ca(2+) influx. The relevance of this Ca(2+) entry for oxidized LDL-stimulated effects is illustrated by the finding that superoxide production was markedly reduced in the absence of external Ca(2+). Finally, inhibition of phagocytosis by cytochalasin B abolished oxidized LDL-stimulated superoxide production without affecting, however, the Ca(2+) mobilization. These effects of oxidized LDL on [Ca(2+)](i) and on respiratory burst of PMN may underlie the occurrence of elevated levels of [Ca(2+)](i) of resting PMN in hypercholesterolemia and represent a mechanism by which PMN can amplify processes in the early phase of atherosclerosis.

The rebound of lipoproteins after LDL-apheresis. Kinetics and estimation of mean lipoprotein levels.

We studied the rebound of lipoproteins in 20 hypercholesterolemic men [mean total cholesterol (TC) levels 9.6+/-1.8 mmol/l] after LDL-apheresis (LA) to determine the rate of recovery and the change in cholesterol synthesis, and to find a uniform estimation for time-averaged levels. After 10-20 months on biweekly LA using dextran sulfate cellulose columns and concomitant simvastatin administration, time-averaged levels (+/-SD) measured by integration of the area under the curve were as follows: TC 4.4+/-1.0 mmol/l, LDL cholesterol (LDL-C) 2.5+/-1.0 mmol/l, apolipoprotein B (apo B) 1. 3+/-0.3 g/l, triglycerides (TG) 1.7+/-0.7 mmol/l, HDL-C 1.1+/-0.2 mmol/l, and lipoprotein(a) [Lp(a)] 53.7+/-49.4 mg/dl. Mean acute reductions in TC, LDL-C, apo B, Lp(a), and TG were 61, 77, 75, 76, and 62%, respectively. HDL-C levels were not influenced. Median recovery half times for TC, LDL-C, apo B, and Lp(a) were 3.0, 4.0, 2. 3, and 3.5 days, respectively. The rebound of Lp(a) was identical to LDL-C, in 12 and 13 days post-treatment, respectively, whereas apo B and TC returned to pre-treatment levels in 7.5 and 10 days, respectively, due to the fast rebound of VLDL particles. Notwithstanding these differences, time-averaged levels (C(AVG)) could be estimated uniformly for the four latter parameters with the formula: C(AVG)=C(MIN)+0.73(C(MAX)-C(MIN)), where C(MAX) and C(MIN) are the immediate pre- and post-treatment levels. During long-term treatment the whole-body cholesterol synthesis was increased as measured by the ratio lathosterol to cholesterol of 3.24+/-1.49 mmol/mmol, whereas no further transient increase in the recovery period after LA was found. In conclusion, long-term LA and simvastatin therapy induced acute and chronic changes in lipids and lipoproteins showing the feasibility of biweekly treatment. It was shown that time-averaged levels, as a measure for the effective plasma levels, can be accurately estimated from pre- and post-treatment levels only.

Apolipoprotein E-deficient mice have an impaired immune response to Klebsiella pneumoniae.

BACKGROUND: All lipoproteins are able to bind to bacterial lipopolysaccharide (LPS), thereby neutralizing its deleterious effects. However, we demonstrated, recently, that in the absence of apolipoprotein E (apoE), eight-fold increased very-low-density lipoprotein levels were not sufficient to protect apoE-deficient (apoE-/-) mice against LPS. During a live Gram-negative infection, mechanisms other than LPS-neutralization may play a role in the pathogenesis of the disease. In the present study we further examined the role of apoE in Gram-negative sepsis. METHODS: Survival, bacterial outgrowth in liver, spleen, kidneys and blood, and tumour necrosis factor-alpha (TNF-alpha) production were measured in apoE-/- mice and control C57BL/6J mice, after an intravenous infection with Klebsiella pneumoniae. RESULTS: Mice that lack apoE showed higher mortality in response to K. pneumoniae than control mice (90% vs. 23% respectively after 2 weeks). ApoE-/- mice had 10-100 times more outgrowth of the bacteria in their organs than controls. Furthermore, circulating TNF-alpha concentrations 90 min after a challenge, were almost twice as high in the apoE-/- mice compared to controls (13.0 +/- 2.9 ng mL-1 vs. 7.6 +/- 3.8 ng mL-1). When apoE-/- and control mice were rendered neutropenic, the discrepancy in survival and outgrowth of K. pneumoniae disappeared. CONCLUSIONS: The apoE-/- mice were more susceptible than control C57BL/6 mice to a K. pneumoniae infection. The absence of apoE may render these mice more susceptible, since this protein is of importance in the detoxification of lipopolysaccharide of Gram-negative bacteria. On the other hand, the phagocytic capacity of granulocytes seems to be decreased in apoE-/- mice, resulting in increased outgrowth and mortality.

The V73M mutation in the hepatic lipase gene is associated with elevated cholesterol levels in four Dutch pedigrees with familial combined hyperlipidemia.

Familial combined hyperlipidemia (FCHL) is a heritable lipid disorder characterized by multiple lipoprotein phenotypes within a single family. Previously, we have shown an increased incidence of mutations in the LPL gene which was associated with elevated levels of very low density lipoprotein (VLDL) and decreased levels of high density lipoprotein among the families studied. Now, we report the results of our study on the hepatic lipase gene. We found the HL V73M variant to be present in four FCHL families. By means of a pedigree-based maximum log-likelihood method we analyzed the effect of this variant on the lipid levels in these families. Carriers of the HL V73M variant revealed significantly higher levels of total cholesterol (P < 0.01) and apoB (P <0.01). These findings show that the HL V73M mutant explains another part of the variability in the phenotype observed among FCHL family members, compared with mutations in the LPL gene. Family analysis shows that in these FCHL families, carriers of mutations in the LPL or HL genes have an increased risk for FCHL compared with their non-carrier relatives.

Binding and transfer of verocytotoxin by polymorphonuclear leukocytes in hemolytic uremic syndrome.

The hemolytic uremic syndrome (HUS) is the most common cause of acute renal failure in children. The role of a verocytotoxin (VT)-producing Escherichia coli has been strongly implicated in the epidemic form of HUS. Although direct toxicity of VT on glomerular endothelial cells has been demonstrated, it remained still unclear how the VT is transported from the intestine to the target organs. In this study we demonstrate that VT, when incubated in whole blood, binds rapidly and completely to human polymorphonuclear leukocytes (PMNs) and not to other components of blood. Binding studies with (125)I-VT-1 showed a single class of binding sites on freshly isolated, nonstimulated human PMNs. The K(d) of VT-binding to PMNs was 10(-8) mol/L, 100-fold less than that of the VT-receptor globotriaosylceramide. On incubation of VT-preloaded PMNs with human glomerular microvascular endothelial cells (GMVECs), transfer of VT-1 to the endothelial cells occurred. Incubation of nonstimulated GMVECs with VT-preloaded PMNs, but not with PMNs or VT-1 alone, caused inhibition of protein synthesis and cell death. Our data are in concert with a role of PMNs in the transfer of VT from the intestine to the kidney endothelium. This transfer occurs by selective binding to a specific receptor on PMNs and subsequent passing of the ligand VT to the VT-receptor on GMVECs, which causes cell damage. This new mechanism further underpins the important role of PMNs in HUS.

Chylomicron processing in familial dysbetalipoproteinemia and familial combined hyperlipidemia studied with vitamin A and E as markers: a new physiological concept.

In previous work we identified a transfer/diffusion process occurring in the postprandial state that more or less contributes to the accumulation of beta-VLDL in familial dysbetalipoproteinemia (FD). Here we present a new theoretical concept underlying chylomicron processing developed on the basis of extended quantitative analyses of fat loading experiments, with both vitamins A and E, performed in patients with familial combined hyperlipidemia (FCH) in comparison to patients with FD and control subjects. Recovery of triglycerides from the fat load in the plasma triglyceride pool was <4%, indicating a very effective lipolysis process with an active remnant generation. Vitamin A from the fat load was, over 48 h, quantitatively recovered in the plasma lipoprotein pool; vitamin E was recovered to 2241%. Nevertheless, transfer/diffusion of both vitamins showed similar patterns. At equilibrium, their contents correlated strongly with the lipoprotein concentrations, the slopes being similar for control subjects and both groups of patients. Only in those FD patients with the highest lipid values, did the vitamin A/lipoprotein mass ratio in the Sf>100 fraction deviate from the total group mean. In the Sf 15-100 fraction, most specific for 'remnants', vitamin A/cholesterol ratios for all subjects were uniform proving that beta-VLDL formation is a thermodynamic process regulated by concentration gradients and the lipophilicity of lipoprotein constituents, not a typical feature for patients with FD. In patients with FD, vitamin A in the plasma pool was recovered excessively (276%) in line with recognition in various pools as a result of the transfer/diffusion process in plasma.

Plasma thiol status in preeclampsia.

OBJECTIVE: To measure plasma thiol levels in women with normal pregnancies, women with preeclampsia, and nonpregnant controls to define plasma thiol's effect on glutathione homeostasis and pathophysiology of preeclampsia. METHODS: Total plasma cysteine, gamma-glutamylcysteine, homocysteine, cysteinylglycine, and glutathione levels were measured in ten nonpregnant women, ten women with normotensive pregnancies, and 20 women with preeclampsia at delivery. RESULTS: Median total plasma levels of all thiols in normotensive pregnant women were significantly lower than in nonpregnant women. Median total plasma cysteine and homocysteine levels in women with preeclampsia were significantly higher compared with pregnant controls (254 versus 190 micromol/L, P < .001; and 13.3 versus 8.4 micromol/L, P < .02, respectively), whereas glutathione levels were significantly lower in women with preeclampsia compared with those in pregnant controls (5.1 versus 6.3 micromol/L, P < .05). CONCLUSION: In women with preeclampsia, homocysteine and cysteine levels, which are lowered in normotensive pregnancy, were comparable to levels in nonpregnant women, whereas glutathione levels were lower. Those results suggest that in women with preeclampsia, glutathione use is higher or its synthesis is disturbed. Therefore, glutathione might affect pathophysiology of preeclampsia.