The role of lipogenesis in the development of uremic hyperlipidemia.

BACKGROUND: It is well documented that hypertriglyceridemia in renal failure mostly is a result of impaired plasma triglyceride (TG) removal. However, the role of TG production in its development is obscure. Therefore, our attention was given to the gene expression of lipogenic enzymes participating in TG biosynthesis. METHODS: We measured some lipogenic enzyme activities, protein abundance (Western blot analysis), and messenger RNA level (Northern blot analysis) in liver and epididymal white adipose tissue (WAT) of rats with surgically induced renal failure (two-stage subtotal nephrectomy). Simultaneously, plasma TG and very low-density lipoprotein (VLDL) concentrations in uremic animals were determined. RESULTS: An increase in plasma TG and VLDL concentrations in rats with renal failure was observed. It was associated with an increase in fatty acid synthase and adenosine triphosphate-citrate lyase (ACL) gene expression in liver and WAT. Moreover, increased activities of malic enzyme, glucose-6-phosphate dehydrogenase, and 6-phosphogluconate dehydrogenase were found. CONCLUSION: Results of the present study provide some evidence that the accumulation of TG-rich lipoproteins in renal insufficiency could be related in part to increased lipogenic enzyme gene expression and, consequently, TG overproduction.

Effect of endogenous and exogenous prostaglandin E(2) on interleukin-1 beta-induced cyclooxygenase-2 expression in human airway smooth-muscle cells.

We studied the effect of endogenous and exogenous prostaglandin E(2) (PGE(2)), a metabolite of arachidonic acid through the cyclooxygenase (COX) pathway, on interleukin (IL)-1 beta-induced COX-2 expression, using primary cultures of human bronchial smooth-muscle cells (HBSMC). Treatment with exogenous PGE(2) resulted in enhanced expression of IL-1 beta-induced COX-2 protein and messenger RNA (mRNA) as compared with the effect of the cytokine per se. Inhibition of PGE(2) production with a nonselective COX inhibitor (flurbiprofen, 10 microM) resulted in a significant reduction in IL-1 beta- induced COX-2 expression, supporting a role of endogenous COX metabolites in the modulation of COX-2 expression. None of the experimental conditions used in the study affected the expression of constitutive cyclooxygenase (COX-1). Treatment with cycloheximide to inhibit translation, and with dexamethasone or actinomycin D to inhibit transcription, linked the effect of PGE(2) to the transcriptional level of COX-2 mRNA rather than to a potential effect on protein and/or mRNA stabilization. PGE(2) increased adenylate cyclase activity in a concentration dependent manner, and forskolin, a direct activator of adenylate cyclase, caused a marked increase in IL-1 beta-dependent COX-2, suggesting the existence of a causal relationship between the two events. The same results were observed with salbutamol, a bronchodilator that acts by increasing cyclic adenosine monophosphate. The effect of PGE(2) on COX-2 expression may contribute to the hypothesized antiinflammatory role of PGE(2) in human airways, providing a self-amplifying loop leading to increased biosynthesis of PGE(2) during an inflammatory event.

Chronic phosphorus supplementation decreases the expression of renal PTH/PTHrP receptor mRNA in rats.

Dietary intake of high levels of phosphorus is known to increase serum levels of parathyroid hormone (PTH); however, how this increased serum PTH affects the action of PTH in major target tissues, particularly by kidney, remains unknown. In the present study, we therefore undertook to clarify this point in intact animals fed a high-P diet by examining various parameters of PTH action. Twelve weanling Wistar male rats were assigned randomly to two groups: a control group with dietary Ca:P = 1:1 and a high-P group (Ca:P = 1:3) fed the standard AIN-76 diet supplemented with P (0.5 and 1.5 g/100 g of diet). After 3 weeks of feeding, in the high-P diet group, we observed that serum Ca was lowered, without a difference in serum P, when compared to the control group. Excretion of urinary cAMP, an index of renal PTH action, was also decreased, with higher excretion of urinary P in those rats fed the high-P diet. In agreement with the decreased cAMP excretion, a clear reduction in PTH/PTH-related protein (PTHrP) receptor gene expression as estimated by Northern blotting was observed in the kidney, despite increased levels of serum PTH. Thus, the present study indicated that a high-P diet reduces PTH action in the kidney, though the serum PTH is increased.

Comparison of the stress response after laparoscopic and open cholecystectomy.

BACKGROUND: We designed a prospective controlled animal study to compare the stress response induced after laparoscopic and open cholecystectomy. METHODS: Twelve female pigs (20-25 kg body weight) were anesthetized with ketamine, pentobarbital, and fentanyl. The animals were randomized into the following four groups: control (C), pneumoperitoneum with CO(2) at 14-15 mmHg (P), laparoscopic cholecystectomy (LC), and open cholecystectomy (OC). The average duration of the procedure in each group was 35 min. RESULTS: Central venous pressure, mean arterial pressure, pulmonary capillary wedge pressure, and cardiac output were monitored. Measurements were recorded when animals were anesthetized (baseline), immediately before and after surgery, and thereafter every 30 min for a maximum of 3 h. White blood cell count (WBC) was determined from blood samples taken before and after 3 h of surgery. Ultrasound-guided liver biopsies were done preoperatively and after 3 h of surgery. Total RNA was isolated from the liver biopsy specimens. Steady-state mRNA levels of beta-fibrinogen (beta-fib), alpha 1-chymotrypsin inhibitor (alpha1-CTI), metallothionein (MT), heat shock protein 70 (Hsp70), and polyubiquitin (Ub) were detected by Northern blot/hybridization. There were no statistical differences in the hemodynamic parameters among the groups. The number of circulating neutrophils and monocytes decreased only after LC. Expression of Hsp70 was not induced after any surgical procedure, and the mRNA levels of Ub did not change after surgery. The expression of alpha1-CTI and beta-fib (acute phase genes) were similarly increased after LC and OC. Steady-state mRNA levels of MT were slightly increased after P and LC but not after OC. CONCLUSION: These data indicate that there are no significant differences between LC and OC in terms of induction of the stress response.

Expression of TGF-beta isoforms and their receptors during mineralized nodule formation by rat periodontal ligament cells in vitro.

Transforming growth factor-betas (TGF-beta s) and bone morphogenetic proteins (BMPs), members of a TGF-beta superfamily, are known to play an important role in osteogenic cell differentiation and consequently bone formation. We have reported previously that periodontal ligament (PDL) cells differentiate and form mineralized nodules when cultured in the presence of dexamethasone (Dex), beta-glycerophosphate (GP) and ascorbic acid (AA). To understand the roles of TGF-beta isoforms (TGF-beta 1, 2 and 3) and TGF-beta type I receptors (activin receptor-like kinase (ALK)-2, -3, -5 and -6) in PDL cell differentiation, their expression was investigated using Northern blot analysis. Rat PDL cells, derived from coagulum in the tooth socket, were cultured in the presence of Dex (5 microM), GP (10 mM) and AA (50 micrograms/ml) for up to 21 d. Total RNA was isolated from PDL cells after 0, 7, 14 and 21 d and used for northern blot analysis of mRNAs for matrix proteins, TGF-beta isoforms and their receptors using 32P-labeled cDNAs as probes. Four stages showing distinct morphological characteristics and matrix expression during development of mineralized nodules were identified. Type I collagen (Col I) and SPARC (secreted protein, acidic and rich in cysteine) mRNAs were expressed at the confluent stage, but decreased during the mineralization stage. Osteopontin (OPN) and alkaline phosphatase (ALP) transcripts were initially observed at multilayer stage, while bone sialoprotein (BSP) and osteocalcin (OC) at the nodule stage and all 4 were expressed thereafter. TGF-beta 1 mRNA expression increased with the progression of PDL cell differentiation, while a relatively high level of TGF-beta 3 transcript decreased slightly during their differentiation. TGF-beta 2 mRNA was not expressed. The expression of TGF beta-RI mRNA decreased, whereas that of TGF beta-RIII increased dramatically with PDL cell differentiation. TGF beta-RII gene activities remained high throughout all stages. ALK-2, ALK-3 and ALK-6 mRNA expression increased with the progression of PDL cell differentiation, suggesting that these receptors may play important roles in Dex-induced PDL cell differentiation and mineralized nodule formation.

Abnormal expression of plasminogen activators in aortic aneurysmal and occlusive disease.

PURPOSE AND METHODS: Aortic aneurysms are characterized by the destruction of the extracellular matrix of the media, whereas occlusive disease involves excess matrix accumulation within the intima. Plasmin degrades extracellular matrix directly and indirectly by activation of latent metalloenzymes. To determine the expression of tissue- and urokinase-type plasminogen activators, immunoassay, fibrin autography, Northern analysis, and immunohistochemistry were performed on specimens of aneurysmal (n = 12), occlusive (n = 8), and healthy (n = 6) aorta. RESULTS: Immunoassay of tissue-type plasminogen activator revealed 8.7 +/- 0.9 ng tissue-type plasminogen activator/mg extracted protein in aneurysmal aorta, 5.7 +/- 0.3 ng/mg in normal aorta, and 2.5 +/- 0.3 ng/mg in occlusive aorta (p < 0.05 for comparisons between all groups). No urokinase-type plasminogen activator antigen was detected by urokinase-type plasminogen activator immunoassay. Fibrin autography exhibited lytic activity at 64 kDa and 54 kDa attributable to tissue-type plasminogen activator and urokinase-type plasminogen activator. The vast majority of fibrinolysis was secondary to free tissue-type plasminogen activator and was greatest in aneurysmal disease and least in occlusive disease. There was only a small amount of lysis secondary to urokinase-type plasminogen activator. Expression of tissue-type plasminogen activator and urokinase-type plasminogen activators mRNA was comparable in aneurysmal and occlusive aortas. In contrast to occlusive disease, aneurysms had an inflammatory cell infiltrate characterized by the expression of urokinase-type plasminogen activator by specific mononuclear cells. Tissue-type plasminogen activator expression was evident in the intima of normal and diseased aorta and in the media of diseased aorta. CONCLUSION: Differential expression of plasminogen activators within the arterial wall may contribute to the unique pathogenesis of aneurysmal and occlusive aortic disease.