Increased Serum Triglyceride Levels Research Articles

Metabolic Effects of Rexinoids: Tissue-Specific Regulation of Lipoprotein Lipase Activity

Hypertriglyceridemia is a frequent complication accompanying the treatment of patients with either retinoids or rexinoids, [retinoid X receptor (RXR)-selective retinoids]. To investigate the cellular and molecular basis for this observation, we have studied the effects of rexinoids on triglyceride metabolism in both normal and diabetic rodents. Administration of a rexinoid such as LG100268 (LG268) to normal or diabetic rats results in a rapid increase in serum triglyceride levels. LG268 has no effect on hepatic triglyceride production but suppresses post-heparin plasma lipoprotein lipase (LPL) activity suggesting that the hypertriglyceridemia results from diminished peripheral processing of plasma very low density lipoproteins particles. Treatment of diabetic rats with rexinoids suppresses skeletal and cardiac muscle but not adipose tissue LPL activity. This effect is independent of changes in LPL mRNA. In C2C12 myocytes, LG268 suppresses the level of cell surface (i.e., heparin-releasable) LPL activity without altering LPL mRNA. This effect is very rapid (t(1/2) = 2 h) and is blocked by the transcriptional inhibitor actinomycin D. These studies demonstrate that RXR ligands can have dramatic effects on the post-translational processing of LPL and suggest that skeletal muscle may be an important target of rexinoid action. In addition, these data underscore that the metabolic consequences of RXR activation are distinct from either retinoic acid receptor or peroxisome proliferator-activated receptor activation.

LDL receptor deficiency unmasks altered VLDL triglyceride metabolism in VLDL receptor transgenic and knockout mice

The very low density lipoprotein receptor (VLDLR) has been proposed to play a role in the delivery of fatty acids to peripheral tissues. However, despite reduced adipose tissue mass in VLDLR-deficient (VLDLR(-)(/-)) mice, this has been difficult to substantiate. In the present study, VLDLR-deficient and VLDLR-overexpressing (PVL) mice were cross-bred onto a low density lipoprotein receptor knockout (LDLR(-)(/-)) background to study the VLDLR under conditions of relatively high serum VLDL and triglyceride levels. Absence of the VLDLR resulted in a significant increase in serum triglyceride levels (1.9-fold) when mice were fed a high fat diet. In contrast, overexpression of the VLDLR resulted in a significant decrease in serum triglyceride levels (2.0-fold) under similar conditions. When kept on a chow diet, a period of prolonged fasting revealed a significant increase in serum triglyceride levels in VLDLR(-)(/-); LDLR(-)(/-) mice (2.3-fold) as compared with LDLR(-)(/-) controls. This could not be attributed to altered apolipoprotein B and VLDL triglyceride production rates. Furthermore, no major differences in nascent VLDL triglyceride content were found between VLDLR(-)(/-); LDLR(-)(/-) mice and LDLR(-)(/-) controls. However, the triglyceride content of circulating VLDL of VLDLR(-)(/-); LDLR(-)(/-) mice (63%) was relatively high as compared with LDLR(-)(/-) controls (49%). These observations suggest that the VLDLR affects peripheral uptake of VLDL triglycerides. In conclusion, under conditions of LDLR deficiency in combination with high fat feeding or prolonged fasting, the effect of the VLDLR on VLDL triglyceride metabolism was revealed.

Association of nonalcoholic fatty liver disease with insulin resistance

BACKGROUND AND PURPOSE: Nonalcoholic fatty liver disease is frequently associated with type 2 diabetes mellitus, obesity, and dyslipidemia, but some patients have normal glucose tolerance or normal weight. We tested the hypothesis that there is an association between nonalcoholic fatty liver disease and insulin resistance that is independent of diabetes and obesity. SUBJECTS AND METHODS: We measured anthropometric and metabolic variables in 46 patients with chronically elevated serum aminotransferase levels, “bright liver” on ultrasound scan, and normal glucose tolerance. Indexes of insulin resistance and secretion were determined using the homeostasis model assessment method. They were compared with 92 normal subjects who were matched for age and sex. RESULTS: Patients with nonalcoholic fatty liver disease were characterized by fasting and glucose-induced hyperinsulinemia, insulin resistance, postload hypoglycemia, and hypertriglyceridemia. Insulin resistance [odds ratio (OR) = 15 per percent increase, 95% confidence interval (CI): 3.0 to 70], fasting triglyceride level (OR = 3.1 per mmol/liter increase, 95% CI: 1.1 to 8.9), 180-minute blood glucose level (OR = 4.3 per mmol/liter decrease, 95% CI: 1.6 to 12), and average insulin concentration in response to oral glucose (OR = 3.0 per 100 pmol/liter increase, 95% CI: 1.5 to 6.2) were independently associated with nonalcoholic fatty liver disease. The exclusion of overweight and obese subjects did not change the results. CONCLUSION: Nonalcoholic fatty liver disease is associated with insulin resistance and hyperinsulinemia even in lean subjects with normal glucose tolerance. Genetic factors that reduce insulin sensitivity and increase serum triglyceride levels may be responsible for its development.

Elevated Serum Triglyceride Levels and Long-Term Mortality in Patients With Coronary Heart Disease

The association between elevated blood triglyceride levels and subsequent mortality risk in patients with established coronary heart disease (CHD) has been investigated rarely. The aim of the present study was to investigate this association. We evaluated mortality over a mean follow-up time of 5. 1 years among 9033 male and 2499 female CHD patients who were screened for participation in the Bezafibrate Infarction Prevention (BIP) Study. A stepwise increase in mortality with increasing serum triglyceride levels was observed in patients with desirable or elevated serum total cholesterol levels and in patients with either desirable or abnormally low HDL cholesterol levels. Multivariate adjustment for factors other than HDL cholesterol yielded a slightly increased adjusted mortality risk with a 1-natural-log-unit elevation of triglyceride levels in men (hazard ratio [HR] 1.14, 95% CI 1.00 to 1.30) and women (HR 1.37, 95% CI 1.04 to 1.88). Excess covariate-adjusted risk was noted among patients with elevated total and LDL cholesterol and in women with HDL cholesterol levels >45 mg/dL. After additional adjustment for HDL cholesterol, the risk of mortality with a 1-natural-log-unit elevation of triglycerides declined in men (HR 1.09, 95% CI 0.94 to 1.26) and in women (HR 1.10, 95% CI 0.80 to 1.50). A trend for increased mortality risk remained in patients with elevated total and LDL cholesterol and in women with HDL cholesterol >45 mg/dL. Elevated triglyceride levels were associated with a small, independent increased mortality risk in CHD patients. This risk may be increased among subgroups of patients with elevated total cholesterol and LDL cholesterol levels.

Effect of long-term beta-carotene and vitamin A on serum cholesterol and triglyceride levels among participants in the Carotene and Retinol Efficacy Trial (CARET)

Objective: The Carotene and Retinol Efficacy Lung Cancer Chemoprevention Trial (CARET) ended prematurely due to the unexpected findings that the active treatment group on the combination of 30 mg β-carotene and 25 000 IU retinyl palmitate had a 46% increased lung cancer mortality and a 26% increased cardiovascular mortality compared with placebo. This study was designed when the CARET intervention was halted to evaluate the effects of long-term supplementation with β-carotene and retinol on serum triglyceride and cholesterol levels, in an attempt to explore possible explanations for the CARET result. Methods: Serum triglyceride levels, and total, high-density lipoprotein (HDL), and low-density lipoprotein (LDL) cholesterol levels were determined in a subgroup of 52 CARET participants. Baseline and mid-trial levels were available on 23 participants on placebo and 29 on active treatment who were then serially followed for 10 months after trial termination. Results: Triglyceride, and total, HDL and LDL cholesterol levels were similar in the two groups at baseline. After a mean of 5 years on the intervention there was a small nonsignificant increase in serum triglyceride levels in the active group, but no difference in total, HDL, or LDL cholesterol levels. After stopping the intervention there was a decrease in triglyceride levels in the active intervention group, and no change in the other parameters. Conclusion: Based on a small convenience sample, CARET participants in the active treatment arm had a small nonsignificant increase in serum triglyceride levels while on the intervention, and a decrease in serum triglyceride levels after the intervention was discontinued. No significant changes in total or HDL cholesterol were noted. These results argue against a major contribution of treatment-induced changes in serum lipid and lipoprotein levels to the increased cardiovascular mortality in the active treatment group.

VLDL-triglyceride production after alcohol ingestion, studied using [2-13C1] glycerol

We used [2-13C1]glycerol to characterize very low density lipoprotein (VLDL)-triglyceride kinetics and intrahepatic glycerol metabolism in normal men (n = 4) after alcohol (EtOH) ingestion. [2-13C1]glycerol was infused before and after the consumption of 48 g EtOH or a placebo. Three additional subjects also received [1-13C1]acetate in addition to the [2-13C1]glycerol with EtOH treatment. Incorporation of tracer into the glycerol or fatty acid moiety of VLDL-triglyceride was measured by gas chromatography-mass spectrometry and used to calculate VLDL-triglyceride production rates. Intrahepatic triose-phosphate enrichments were also calculated based on mass isotopomer distribution analysis of plasma glucose. There was no difference in VLDL-triglyceride production rates after 48 g EtOH (11.9 +/- 3.7 mg/kg/h) or placebo (14.7 +/- 3. 3 mg/kg/h). The VLDL-triglyceride rate constants calculated by kinetic modeling using the glycerol and acetate tracers in the combined isotope infusion subjects were very closely correlated (r 2 = 0.94). The peak VLDL-glycerol enrichments after EtOH were 22.5 +/- 3.3% versus 7.6 +/- 0.8% after placebo (P < 0.001), while intrahepatic triose-phosphate enrichments were 19.8 +/- 1.3% and 13. 1 +/- 1.2% (P < 0.001), respectively. Moreover, the calculated asymptotic VLDL-glycerol enrichments (representing the hepatic alpha-glycerol phosphate enrichment) were significantly higher after EtOH than placebo. The higher ratio of VLDL-glycerol to triose-phosphate labeling after EtOH suggests a metabolic block at glycerol 3-phosphate dehydrogenase. We conclude that consumption of 48 g EtOH does not increase VLDL-triglyceride production in normal men but does cause accumulation of tracer in hepatic alpha-glycerol phosphate.

Increased serum triglyceride levels occurred in 4/9 renal transplant recipients receiving sirolimus

Increased serum triglyceride levels occurred in 4/9 renal transplant recipients receiving sirolimus

Longitudinal studies in geriatric medicine

The results of longitudinal studies in geriatric medicine were reviewed by referring to relatively recent publications. "Longidufinal studies" comprised not only cohort studies but also prospective case-control studies in the broad sense. Poor self-rated health, weight loss hypoalbuminemia, inability to perform activities of daily living, low levels of physical activity, and cognitive dysfunction, all of which could be manifestations of chronic diseases, might shorten longevity. Cardiomegaly or left ventricular hypertrophy on ECG were again found to be important risk factors for cardiovascular disease in the aged, because of their relation to atherosclerosis. There is no evidence regarding the contribution of hyperlipidemia to the risk of cardiovascular disease in the aged, although insulin resistance can increase serum triglyceride levels and reduced level of high-density lipoprotein cholesterol even in the aged. Mortality due to stroke and heart disease have been decreasing in most developed countries, and several recent community-based studies have also shown decreases in the incidence of cerebral stroke. Large-scale case-control studies on the pharmacological treatment of hyperlipidemia have resulted in both primary and secondary prevention of coronary heart disease. However, information concerning the effects of treatment for hyperlipidemia on coronary heart disease in the aged is limited. Results of large-scale case-control studies indicate that pharmacological treatment of elderly hypertensive patients can reduce cardiovascular morbidity and mortality, and angiotensin-converting enzyme inhibitors have recently been shown ot be useful.

A single-masked study comparing doxazosin and enalapril in patients with non—insulin-dependent diabetes mellitus and hypertension

Angiotensin-converting enzyme (ACE) inhibitors are recognized as eminently suitable drugs for the treatment of hypertensive patients with non—insulin-dependent diabetes mellitus (NIDDM). They are metabolically neutral, may reduce insulin resistance, and are reno-protective. Long-acting alpha 1-blockers such as doxazosin are also metabolically neutral, effective antihypertensive agents. The objective of this study was to compare the efficacy and acceptability of doxazosin and the ACE inhibitor enalapril. We investigated the effects of these drugs on blood pressure, diabetic control, lipid levels, renal function, and safety in patients with NIDDM (type II diabetes) and mild-to-moderate hypertension. Fifty-two patients with NIDDM and stable essential hypertension were randomized to two parallel groups. The study comprised three phases: placebo washout (4 weeks), dose adjustment monotherapy of doxazosin 1 to 4 mg/d or enalapril 5 to 20 mg/d (8 weeks), and maintenance (4 weeks). Patients not controlled on monotherapy entered a 4-week, open-label, dual-therapy phase before maintenance. Black patients were excluded, as were those with macroalbuminuria (urinary albumin >3.5 g/24 h) and renal failure (serum creatinine ⩾150 μmol/L). Variables being compared included critical blood pressure (CBP) (ie, the lesser of mean sitting and standing diastolic blood pressure [DBP]), sitting and standing systolic blood pressure (SBP) and DBP, blood glucose (fasting and postprandial), serum cholesterol levels, serum triglyceride levels, body mass index (BMI), and electrocardiographic (ECG) evidence of left ventricular hypertrophy. Patients in the doxazosin group exhibited a larger decrease in CBP (−11.3 vs −6.2 mm Hg), sitting (−9.9 vs −1.1) and standing SBP (−10.3 vs 0.0), and sitting (−12.2 vs −8.4) and standing DBP (−7.9 vs −0.8) compared with the enalapril group. The difference in the reduction in standing DBP was statistically significant, whereas the other differences did not reach statistical significance. No statistically significant differences were found between the groups in metabolic variables, BMI, or ECG findings. The metabolic profiles of enalapril and doxazosin were similar, except for a mild increase in serum triglyceride levels in the doxazosin group. However, the confidence index for the doxazosin-enalapril difference was wide, meaning that no conclusive statement can be made about the difference. Adverse events were common (26.9% doxazosin vs 42.3% enalapril), but none were serious. The doxazosin-treated patients showed a larger decrease in blood pressure on average than patients receiving enalapril; apart from standing DBP, the differences were not statistically significant. This study has demonstrated that doxazosin is at least as affective as enalapril in decreasing blood pressure in patients with NIDDM and mild-to-moderate hypertension.

Hypolipidemic action of F-1394, an acyl-CoA: cholesterol acyltransferase (ACAT) inhibitor, in high-fat diet fed beagle dogs

In the present study, we investigated the hypolipidemic effect of F-1394, a potent and selective inhibitor of acyl-CoA: cholesterol acyltransferase (ACAT), in dogs fed with a high-fat diet consisting of regular foods, 5% cholesterol and 16% fat. The serum cholesterol levels in dogs reached the steady-state 1 week after the start of feeding of a high-fat diet and were about 2-fold greater than those in normolipidemic dogs. Graded administration of the doses of F-1394 (1-30 mg/kg/d) to the dogs fed with a high-fat diet prevented the elevation of serum cholesterol levels. In the hyperlipidemic dogs fed with a high-fat diet for 14 d before the start of the administration of F-1394, the oral administration of F-1394 at a dose of 1, 3 or 10 mg/kg/d for 21 d reduced the serum cholesterol levels in a dose-dependent manner. The estimated ID50 value was 7.2 +/- 0.3 mg/kg/d p. o. (12.1 +/- 0.5 mol/kg/d p. o.). F-1394 did not affect the body weight and no diarrhea was observed by the administration of F-1394. F-1394 at a dose of 10 mg/kg/d or more also significantly inhibited the increase of serum triglyceride levels 3 h after the feeding of high-fat diet. These results suggest that F-1394 inhibits the ACAT activity in the canine small intestine and, subsequently, the inhibition of ACAT activity contributes much to the prevention of cholesterol absorption via the gut, resulting in a decrease in serum cholesterol levels in the dogs fed with high-fat diet. Furthermore, F-1394 may also have an inhibitory effect on the triglyceride absorption via the gut, and the therapeutical use for postprandial hypertriglyceridemia is expected.

In the absence of the low density lipoprotein receptor, human apolipoprotein C1 overexpression in transgenic mice inhibits the hepatic uptake of very low density lipoproteins via a receptor-associated protein-sensitive pathway.

To study the role of apoC1 in lipoprotein metabolism, we have generated transgenic mice expressing the human APOC1 gene. On a sucrose-rich diet, male transgenic mice with high APOC1 expression in the liver showed elevated levels of serum cholesterol and triglyceride compared with control mice (5.7+/-0.7 and 3.3+/-2.1 vs. 2.7+/-0.1 and 0.4+/-0.1 mmol/liter, respectively). These elevated levels were mainly confined to the VLDL fraction. Female APOC1 transgenic mice showed less pronounced elevated serum lipid levels. In vivo VLDL turnover studies revealed that, in hyperlipidemic APOC1 transgenic mice, VLDL particles are cleared less efficiently from the circulation as compared with control mice. No differences were observed in the hepatic production and extrahepatic lipolysis of VLDL-triglyceride. Also, VLDL isolated from control and APOC1 transgenic mice were found to be equally good substrates for bovine lipoprotein lipase in vitro. These data indicate that the hyperlipidemia in APOC1 transgenic mice results primarily from impaired hepatic VLDL particle clearance, rather than a defect in the hydrolysis of VLDL-triglyceride. To investigate which hepatic receptor is involved in the apoC1-mediated inhibition of VLDL clearance, APOC1 transgenic mice were bred with an LDL receptor-deficient (LDLR(-/-)) background. In addition, control, LDLR(-/-), and LDLR(-/-)/APOC1 mice were transfected with adenovirus carrying the gene for the receptor-associated protein (Ad-RAP). Both serum cholesterol and triglyceride levels were strongly elevated in LDLR(-/-)/APOC1 mice compared with LDLR(-/-) mice (52+/-19 and 36+/-19 vs. 8.4+/-0.9 and 0.5+/-0.2 mmol/liter, respectively), indicating that apoC1 inhibits the alternative VLDL clearance pathway via the remnant receptor. Transfection of LDLR(-/-) mice with Ad-RAP strongly increased serum cholesterol and triglyceride levels, but to a lesser extent than those found in LDLR(-/-)/APOC1 mice (39+/-8 and 17+/-8 vs. 52+/-19 and 36+/-19 mmol/liter, respectively). However, in LDLR(-/-)/APOC1 mice the transfection with Ad-RAP did not further increase serum cholesterol and triglyceride levels (52+/-19 and 36+/-19 vs. 60+/-10 and 38+/-7 mmol/liter, respectively). From these studies we conclude that, in the absence of the LDLR, apoC1 inhibits the hepatic uptake of VLDL via a RAP-sensitive pathway.

Keratinocyte growth factor increases fatty acid mobilization and hepatic triglyceride secretion in rats.

Keratinocyte growth factor (KGF) is a member of the fibroblast growth factor family that was originally identified as a keratinocyte mitogen after isolation from a lung fibroblast cell line. In this study, we demonstrate that administration of KGF to mice and rats elevates serum lipid levels. In rats, 1 h after KGF administration, serum triglyceride and FFA levels were increased, with peak values at 2 h (1.9-fold increase). The increase in serum triglyceride levels was sustained for at least 16 h. Serum cholesterol levels were also increased, but the effect was delayed beginning at 4 h, with peak values at 16 h (1.27-fold increase). KGF did not decrease the clearance of triglyceride-rich lipoproteins, but increased hepatic triglyceride secretion. KGF stimulated lipolysis, but not hepatic de novo fatty acid synthesis, and the increased delivery of FFA to the liver plays a crucial role in the KGF-induced hypertriglyceridemia. Neither alpha- nor beta-adrenergic receptor antagonists affected the hypertriglyceridemia induced by KGF, indicating that endogenous catecholamines are not involved in mediating KGF-induced hypertriglyceridemia. These results demonstrate that KGF induces hypertriglyceridemia by increasing hepatic triglyceride secretion, with the fatty acids provided by lipolysis making a major contribution. Thus, KGF could modulate lipid metabolism in vivo.

Keratinocyte growth factor increases fatty acid mobilization and hepatic triglyceride secretion in rats

Keratinocyte growth factor (KGF) is a member of the fibroblast growth factor family that was originally identified as a keratinocyte mitogen after isolation from a lung fibroblast cell line. In this study, we demonstrate that administration of KGF to mice and rats elevates serum lipid levels. In rats, 1 h after KGF administration, serum triglyceride and FFA levels were increased, with peak values at 2 h (1.9-fold increase). The increase in serum triglyceride levels was sustained for at least 16 h. Serum cholesterol levels were also increased, but the effect was delayed beginning at 4 h, with peak values at 16 h (1.27-fold increase). KGF did not decrease the clearance of triglyceride-rich lipoproteins, but increased hepatic triglyceride secretion. KGF stimulated lipolysis, but not hepatic de novo fatty acid synthesis, and the increased delivery of FFA to the liver plays a crucial role in the KGF-induced hypertriglyceridemia. Neither alpha- nor beta-adrenergic receptor antagonists affected the hypertriglyceridemia induced by KGF, indicating that endogenous catecholamines are not involved in mediating KGF-induced hypertriglyceridemia. These results demonstrate that KGF induces hypertriglyceridemia by increasing hepatic triglyceride secretion, with the fatty acids provided by lipolysis making a major contribution. Thus, KGF could modulate lipid metabolism in vivo.

17β-Estradiol treatment increases the levels of estrogen receptor and its mRNA in male rat liver

This study examined estrogen receptor dynamics in the livers of male obses rats ( SHHF Mcc-cp ) treated for two weeks with a continuous, low dose of 17β-estradiol compared with untreated controls. An increased binding capacity for tritiated 17β-estradiol in the cytosol, consistent with binding to the estrogen receptor, was demonstrated in treated males relative to control males ( P < 0.01). These observations were confirmed using curve-peeling techniques with saturation analysis, ammonium sulfate precipitation/fractionation of cytosol protein, and chromatographic techniques to isolate the high-affinity binding from other interfering factors. Increased hepatic nuclear estrogen receptor levels in treated males (112.3 ± 8.3 fmol/g liver) compared with controls (64.1 ± 6.8 fmol/g liver) suggested that the liver was under estrogenic influences. This interpretation was supported by an increase in serum triglyceride levels, reflecting increased very low density lipoprotein secretion by the liver. Reductions in testosterone levels and in the weights of seminal vesicles and the testes in treated males indicated detrimental effects on reproduction. An interpretation of increased synthesis of estrogen receptor with 17β-estradiol treatment was supported by the observation of an increase in the mRNA for estrogen receptor. Taken together, these observations indicate that continuous, low-dose 17β-estradiol treatment induces estrogenic action in the livers of male rats and also increases hepatic estrogen receptor, probably indirectly, via an increase in its mRNA.

Gout, uric acid metabolism, and crystal-induced inflammation

Serum triglyceride levels are significantly higher and serum high-density lipoprotein cholesterol levels are lower in patients with gout compared with healthy individuals. Whereas increased serum triglyceride levels exist intrinsically in gout, serum uric acid concentration correlates inversely with insulin sensitivity and positively with serum triglycerides. Interaction of monosodium urate crystals with granulocyte-macrophage colony-stimulating factor and with tumor necrosis factor-activated neutrophils favored the production of interleukin-1 over that of interleukin-1-Ra, resulting in a proinflammatory imbalance. Interaction of the crystals with iron or tyrosine kinase may modify their inflammatory response and can be an important modulating mechanism in gouty arthritis. E-selectin is a specific marker for synovial fluid soluble endothelial activity and is increased in the synovial fluid of patients with gouty arthritis, as well as in that of patients with other inflammatory arthritides. Similarly, E-selectin was found to be high in joints with monosodium urate crystal-induced synovitis. In addition, synovial fluid levels of interleukin-8 were found to be high in gout, rheumatoid arthritis, and osteoarthritis.

52A Effectiveness of a placebo run-in period in increasing the power of a chemoprevention trial, CARET

Objective: The Carotene and Retinol Efficacy Lung Cancer Chemoprevention Trial (CARET) ended prematurely due to the unexpected findings that the active treatment group on the combination of 30 mg β-carotene and 25 000 IU retinyl palmitate had a 46% increased lung cancer mortality and a 26% increased cardiovascular mortality compared with placebo. This study was designed when the CARET intervention was halted to evaluate the effects of long-term supplementation with β-carotene and retinol on serum triglyceride and cholesterol levels, in an attempt to explore possible explanations for the CARET result. Methods: Serum triglyceride levels, and total, high-density lipoprotein (HDL), and low-density lipoprotein (LDL) cholesterol levels were determined in a subgroup of 52 CARET participants. Baseline and mid-trial levels were available on 23 participants on placebo and 29 on active treatment who were then serially followed for 10 months after trial termination. Results: Triglyceride, and total, HDL and LDL cholesterol levels were similar in the two groups at baseline. After a mean of 5 years on the intervention there was a small nonsignificant increase in serum triglyceride levels in the active group, but no difference in total, HDL, or LDL cholesterol levels. After stopping the intervention there was a decrease in triglyceride levels in the active intervention group, and no change in the other parameters. Conclusion: Based on a small convenience sample, CARET participants in the active treatment arm had a small nonsignificant increase in serum triglyceride levels while on the intervention, and a decrease in serum triglyceride levels after the intervention was discontinued. No significant changes in total or HDL cholesterol were noted. These results argue against a major contribution of treatment-induced changes in serum lipid and lipoprotein levels to the increased cardiovascular mortality in the active treatment group.

Analysis of plasma fibrinolysis in the patients with acute cerebral infarction.

In the present study, the plasma fibrinolytic activity in 30 cases of cortical artery territory cerebral infarction (CACI) and 32 cases of perforating artery territory cerebral infarction (PACI) within 3 days after ictus, and 30 sex- and age-matched controls without cardio-cerebrovascular diseases were evaluated by a comprehensive panel of assay, including the plasma tPA activity, PAI activity, endothelial capacity of tPA release and PAI/tPA ratio. The results showed that the plasma fibrinolysis and the endothelial potential to release tPA responding to stimulation in both subtypes of the patients were significantly lower than those in the controls, which provide the theoretical basis for carrying out the thrombolytic therapy in the ischemic stroke. And the study also suggested that increased plasma PAI activity could increase the risk of AS thrombotic events with increased serum triglyceride level.

Interleukin-6 stimulates hepatic triglyceride secretion in rats.

Interleukin-6 (IL-6) not only regulates a variety of immune functions, but also is the most potent cytokine in inducing the hepatic acute phase proteins. We determined the effect of IL-6 on serum lipid levels and the mechanism of IL-6-induced hypertriglyceridemia in rats. Intravenous administration of IL-6 (0.1-10 micrograms/200 g BW) increased serum triglyceride levels in a dose-dependent manner. One hour after IL-6 administration, serum triglyceride levels were increased, with peak values at 2 h (2.2-fold increase). Serum cholesterol levels also increased, but the effect was delayed, first occurring at 4 h and peaking at 8 h (1.24-fold increase). IL-6 treatment increased hepatic triglyceride secretion without decreasing the clearance of triglyceride-rich lipoproteins, indicating that the hypertriglyceridemia was due to increased secretion by the liver. Furthermore, IL-6 stimulates lipolysis, and the increased delivery of FFA to the liver significantly contributed to the IL-6-induced hypertriglyceridemia. Neither alpha 1- nor beta-adrenergic receptor antagonists affected the hypertriglyceridemia induced by IL-6, whereas previous studies have shown that endotoxin-induced hypertriglyceridemia was blocked by alpha-adrenergic receptor antagonists. These results demonstrate that IL-6 induces hypertriglyceridemia by stimulating hepatic triglyceride secretion independent of endogenous catecholamines. Thus, changes in hepatic triglyceride metabolism are another acute phase response that can be induced by IL-6.

Induction of a hepatic toxic syndrome in the Dutch-belted rabbit by a quinoxalinone anxiolytic

The non-benzodiazepine anxiolytic, panadiplon, was discontinued from clinical development due to evidence of hepatic toxicity in human volunteers that was not predicted by rat or monkey preclinical development studies. The present study was conducted to examine potential toxicity in the rabbit. Three groups of female rabbits were administered vehicle, 10 mg/kg per day or 20 mg/kg per day of panadiplon by oral gavage for 14 days. Animals in the 20 mg/kg group lost weight, and 6 10 developed a profound lethargy. Hepatic toxicity was observed in treated animals, evidenced by dose- and time-related increases in serum transaminase activities, gross hepatic lesions and multifocal centrilobular necrosis. Hepatic microvesicular steatosis was evident in treated animals; lipid analysis revealed a 123% increase in hepatic triglyceride. A time-dependent increase in serum triglyceride levels was observed in the high-dose group beginning on day 4. Hepatic glycogen was reduced, and histochemical examination revealed the reduction to be heterogeneous across the lobule with some areas showing a complete absence of glycogen. One rabbit in each drugtreated group showed mild hypoglycemia at day 12, and 4 10 rabbits in the high-dose group showed hyperglycemia at days 12–14. We conclude that panadiplon produced a microvesicular steatosis and hepatic toxicity in the rabbit. The observed toxicity resembled a Reye's syndrome-like toxicity produced by a variety of mitochondrial fatty acid oxidation inhibitors.

The effect of gamma-hexachlorocyclohexane (lindane) on the activities of liver lipogenic enzymes and on serum lipids in rats.

The effect of dietary gamma-hexachlorocyclohexane (lindane) (50-350 ppm, 0.17-1.19 mumol/kg chow) on the activity of enzymes of lipogenesis, viz., fatty acid synthase (FAS; EC 2.3.1.85), citrate cleavage enzyme (CCE; EC 4.1.3.8), malic enzyme (ME; EC 1.1.1.40), glucose-6-phosphate dehydrogenase (G6PDH; EC 1.1.1.49) and 6-phosphogluconate dehydrogenase (PGDH; EC 1.1.1.44), and on serum lipid levels, was investigated in livers of 35-day-old male Wistar rats. Lindane (150 ppm) caused a substantial decline of enzyme activities within the first 24 h of treatment. The decrease was transient, however, and enzyme activities subsequently recovered despite continuation of lindane feeding. The recovery of enzyme activities was comparatively fast in the case of ME, G6PDH and PGDH, but very slow with FAS and CCE. Activities of lipogenic enzymes decrease when animals are starved, and increase much beyond prestarvation levels upon subsequent refeeding. Lindane in the refeeding diet blunted this overshoot of FAS and CCE activities in a dose-dependent manner. In contrast, activities of Me, G6PDH and PGDH responded to low dietary lindane concentrations with a substantial stimulation of the increase of activity, whereas at high lindane concentrations the overshoot was inhibited. According to their responses to lindane exposure, liver lipogenic enzymes could be grouped into 2 categories with FAS and CCE representing one and ME, G6PDH and PGDH representing the other group. Polychlorinated biphenyls (PCBs) in the diet caused basically opposite changes of the activities of the lipogenic enzymes. Co-administration of lindane and PCBs resulted in an apparent cancellation of effects, suggesting that lindane and PCBs affect fatty acid synthesis at opposite points.(ABSTRACT TRUNCATED AT 250 WORDS)