Biomedical subjects
Publications and source records attributed to T Chajek-Shaul.
We report a case of a 74-year-old woman exhibiting the yellow nail syndrome in association with ipsilateral xanthogranulomatous pyelonephritis. Nephrectomy resulted in complete resolution of the pleural effusion and slow improvement of the yellow nails. This report calls attention to the renal-related pleural effusion, and to the thorough investigation needed for the yellow nail syndrome.
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Fragments of human adipose tissue were maintained in culture for 1 week in a medium containing 1 mU/ml insulin and 100 ng/ml dexamethasone. Under these conditions lipoprotein lipase activity was present in human adipose tissue fragments which converted [14C]glucose to 14CO2 and [14C]triglyceride. Both metabolic parameters studied were affected by human tumor necrosis factor and brefeldin A. When fragments of human adipose tissue after 1 week in culture were incubated with nicotine tartrate for 20 h, a slight but significant increase in lipoprotein lipase activity was observed, and an increased conversion of [14C]glucose to 14CO2 and [14C]triglyceride occurred. Nicotine was taken up by human adipose tissue, but no conversion to cotinine was observed. Our data demonstrate a direct effect of nicotine on human adipose tissue metabolism. Furthermore, it is suggested that weight loss in smokers is a multifactorial phenomenon, and one of the important factors to be considered is the direct effect of nicotine within the tissue.
Several types of transgenic mice were used to study the influence of hypertriglyceridemia and cholesteryl ester transfer protein (CETP) expression on high density lipoprotein (HDL) levels, particle sizes, and metabolism. The presence of the CETP transgene in hypertriglyceridemic human apo CIII transgenic mice lowered HDL-cholesterol (HDL-C) 48% and apolipoprotein (apo) A-I 40%, decreased HDL size (particle diameter from 9.8 to 8.8 nm), increased HDL cholesterol ester (CE) fractional catabolic rate (FCR) 65% with a small decrease in HDL CE transport rate (TR) and increased apo A-I FCR 15% and decreased apo A-I TR 29%. The presence of the CETP transgene in hypertriglyceridemic mice with human-like HDL, human apo A-I apo CIII transgenic mice, lowered HDL-C 61% and apo A-I 45%, caused a dramatic diminution of HDL particle size (particle diameters from 10.3 and 9.1 to 7.6 nm), increased HDL CE FCR by 107% without affecting HDL CE TR, and increased apo A-I FCR 35% and decreased apo A-I TR 48%. Moreover, unexpectedly, hypertriglyceridemia alone in the absence of CETP was also found to cause lower HDL-C and apo A-I levels primarily by decreasing TRs. Decreased apo A-I TR was confirmed by an in vivo labeling study and found to be associated with a decrease in intestinal but not hepatic apo A-I mRNA levels. In summary, the introduction of the human apo A-I, apo CIII, and CETP genes into transgenic mice produced a high-triglyceride, low-HDL-C lipoprotein phenotype. Human apo A-I gene overexpression caused a diminution of mouse apo A-I and a change from monodisperse to polydisperse HDL. Human apo CIII gene overexpression caused hypertriglyceridemia with a significant decrease in HDL-C and apo A-I levels primarily due to decreased HDL CE and apo A-I TR but without a profound change in HDL size. In the hypertriglyceridemic mice, human CETP gene expression further reduced HDL-C and apo A-I levels, primarily by increasing HDL CE and apo A-I FCR, while dramatically reducing HDL size. This study provides insights into the genes that may cause the high-triglyceride, low-HDL-C phenotype in humans and the metabolic mechanisms involved.
We have characterized the importance of size, sulfation, and anticoagulant activity of heparin in release of basic fibroblast growth factor (bFGF) from the subendothelial extracellular matrix (ECM) and the luminal surface of the vascular endothelium. For this purpose, 125I-bFGF was first incubated with ECM and confluent endothelial cell cultures, or administered as a bolus into the blood of rats, the immobilized 125I-bFGF was then subjected to release by various chemically modified species of heparin and size-homogeneous oligosaccharides derived from depolymerized heparin. Both totally desulfated and N-desulfated heparin failed to release the ECM-bound bFGF. Likewise, substitution of N-sulfate groups of heparin and low molecular weight heparin (fragmin) by acetyl or hexanoyl residues resulted in an almost complete inhibition of bFGF release by these polysaccharides. The presence of O-sulfate groups in heparin increased but was not critical for release of ECM-bound bFGF. Similar structural requirements were identified for release of 125I-bFGF bound to low-affinity sites on the surface of vascular endothelial cells. Oligosaccharides derived from depolymerized heparin and containing as little as 8-10 sugar units were, on a weight basis, equivalent to whole heparin in their ability to release bFGF from ECM. Low-sulfate oligosaccharides were less effective releasers of bFGF as compared to medium- and high-sulfate fractions of the same size oligosaccharides. Heparin fractions with high and low affinity to antithrombin III exhibited a similar high bFGF-releasing activity despite a 200-fold difference in their anticoagulant activities.(ABSTRACT TRUNCATED AT 250 WORDS)
We have previously described two transgenic mouse lines, one heterozygous for the human apo A-I gene and the other heterozygous for a human cholesteryl ester transfer protein (CETP) minigene driven by the mouse metallothionein-I gene promoter. In the current study, these two lines were crossed producing control, HuCETPTg, HuAITg, and HuAICETPTg mice to study the influence of CETP on HDL cholesterol levels, particle size distribution, and metabolism in animals with mouse and human-like HDL. In the HuCETPTg and HuAICETPTg animals, zinc induction approximately doubled plasma CETP activity, with no activity in plasma from the control and HuAITg animals. The only significant effect of CETP on lipoprotein subfraction cholesterol concentrations was for HDL-C. Compared to control animals, HuCETPTg animals had lower HDL-C, 20% before and 35% after Zn induction, and compared to HuAITg animals, HuAICETPTg animals had lower HDL-C, 35% before and 66% after Zn induction. Control and HuCETPTg HDL consist primarily of a single size population with a mean diameter of 10.00 +/- 0.10 nm and 9.71 +/- 0.05 nm, respectively. HuAITg HDL consists primarily of three distinct HDL size subpopulations with peak diameters of 10.35 +/- 0.08 nm, 8.80 +/- 0.06 nm, 7.40 +/- 0.10 nm, and HuAICETPTg HDL also consists primarily of three distinct HDL size subpopulations with peak diameters of 9.87 +/- 0.05 nm, 8.60 +/- 0.10 nm, 7.30 +/- 0.15 nm before, and 9.71 +/- 0.08 nm, 8.50 +/- 0.11 nm, 7.27 +/- 0.15 nm after zinc induction, respectively. Western blotting analysis of nondenaturing gradient gels of plasma with a monoclonal antibody to CETP indicated that in HuCETPTg and HuAICETPTg mice, 22 and 100%, respectively, of the CETP was HDL associated. Turnover studies with HDL doubly labeled with 125I apo A-I and 3H cholesteryl linoleate indicated that the CETP-induced fall in HDL-C was associated with increased HDL-cholesterol ester fractional catabolic rate in both the absence and presence of human apo A-I, suggesting CETP-mediated transfer of HDL-cholesterol ester to apo B-containing lipoproteins. In summary, these studies suggest that CETP has a much more profound effect on HDL cholesterol levels in transgenic animals expressing human apo A-I. This may be due to an enhanced interaction of CETP with human compared to mouse apo A-I or to the HDL particles they produce.
Hypertriglyceridemia is common in the general population, but its mechanism is largely unknown. In previous work human apo CIII transgenic (HuCIIITg) mice were found to have elevated triglyceride levels. In this report, the mechanism for the hypertriglyceridemia was studied. Two different HuCIIITg mouse lines were used: a low expressor line with serum triglycerides of approximately 280 mg/dl, and a high expressor line with serum triglycerides of approximately 1,000 mg/dl. Elevated triglycerides were mainly in VLDL. VLDL particles were 1.5 times more triglyceride-rich in high expressor mice than in controls. The total amount of apo CIII (human and mouse) per VLDL particle was 2 and 2.5 times the normal amount in low and high expressors, respectively. Mouse apo E was decreased by 35 and 77% in low and high expressor mice, respectively. Under electron microscopy, VLDL particles from low and high expressor mice were found to have a larger mean diameter, 55.2 +/- 16.6 and 58.2 +/- 17.8 nm, respectively, compared with 51.0 +/- 13.4 nm from control mice. In in vivo studies, radiolabeled VLDL fractional catabolic rate (FCR) was reduced in low and high expressor mice to 2.58 and 0.77 pools/h, respectively, compared with 7.67 pools/h in controls, with no significant differences in the VLDL production rates. In an attempt to explain the reduced VLDL FCR in transgenic mice, tissue lipoprotein lipase (LPL) activity was determined in control and high expressor mice and no differences were observed. Also, VLDLs obtained from control and high expressor mice were found to be equally good substrates for purified LPL. Thus excess apo CIII in HuCIIITg mice does not cause reduced VLDL FCR by suppressing the amount of extractable LPL in tissues or making HuCIIITg VLDL a bad substrate for LPL. Tissue uptake of VLDL was studied in hepatoma cell cultures, and VLDL from transgenic mice was found to be taken up much more slowly than control VLDL (P < 0.0001), indicating that HuCIIITg VLDL is not well recognized by lipoprotein receptors. Additional in vivo studies with Triton-treated mice showed increased VLDL triglyceride, but not apo B, production in the HuCIIITg mice compared with controls. Tissue culture studies with primary hepatocytes showed a modest increase in triglyceride, but not apo B or total protein, secretion in high expressor mice compared with controls. In summary, hypertriglyceridemia in HuCIIITg mice appears to result primarily from decreased tissue uptake of triglyceride-rich particles from the circulation, which is most likely due to increased apo CIII and decreased apo E on VLDL particles. the HuCIIITg mouse appears to be a suitable animal model of primary familial hypertriglyceridemia, and these studies suggest a possible mechanism for this common lipoprotein disorder.
Transgenic mice carrying the human apolipoprotein (apo) A-I gene (HuAITg mice) were used to examine the effects of overexpression of the human gene on high density lipoprotein (HDL) particle size distribution and metabolism. On a chow diet, control mice had HDL cholesterol and apo A-I levels of 49 +/- 2 and 137 +/- 12 mg/dl of plasma, respectively. HuAITg mice had HDL cholesterol, human apo A-I, and mouse apo A-I levels of 88 +/- 2, 255 +/- 19, and 16 +/- 2 mg/dl, respectively. Nondenaturing gradient gel electrophoresis revealed control mouse plasma HDL to be primarily monodisperse with a particle diameter of 10.2 nm, whereas HuAITg mouse plasma HDL was polydisperse with particles of diameter 11.4, 10.2, and 8.7 nm, which correspond in size to human HDL1, HDL2, and HDL3, respectively. In vivo turnover studies of HDL labeled with [3H]cholesteryl linoleyl ether (representing the cholesteryl ester pool) and 125I-apo A-I were performed. In control animals, the fractional catabolic rate (FCR) for HDL cholesteryl ester (0.197 +/- 0.010 pool/hr) was significantly (P less than 0.0005) more than the apo A-I FCR (0.118 +/- 0.006 pool/hr). In the HuAITg mice, the HDL cholesteryl ester FCR (0.124 +/- 0.008 pool/hr) was the same as the apo A-I FCR (0.126 +/- 0.010 pool/hr). There were no significant differences between control and HuAITg animals in the sites of tissue removal of HDL cholesteryl ester, with the liver extracting most of the injected radioactivity. Control and HuAITg animals had comparable liver and intestinal cholesterol synthesis and LDL FCR. In conclusion, HuAITg mice have principally human and not mouse apo A-I in their plasma. This apparently causes a change in HDL particle size distribution in the transgenic mice to one resembling the human pattern. The replacement of mouse by human apo A-I also apparently causes the loss of the selective uptake pathway of HDL cholesteryl esters present in control mice. These data imply that apo A-I primary structure has a profound influence on HDL particle size distribution and metabolism.
The effect of human recombinant interleukin-1 (IL-1) on the regulation of lipoprotein lipase (LPL) was studied in rat heart mesenchymal cell cultures. A time-dependent reduction in enzyme activity occurred with a 30% fall after 1 h. The suppression of enzyme activity was accompanied by a commensurate reduction in enzyme mass. The reduction in LPL activity was most prominent in the heparin releasable pool; IL-1 treatment resulted in a 7.2-8.3-fold decrease in the functional compartment and a 2.5-2.8-fold decrease in residual cellular activity. The effect of IL-1 could be prevented by the addition of the IL-1 inhibitor. However, in contradistinction to the effect of tumor necrosis factor (TNF), there was no change in LPL mRNA in cultures treated with IL-1. The present results show that the regulation of LPL in mesenchymal heart cell cultures by IL-1 occurs posttranscriptionally, as has been shown in 3T3 cells. The more pronounced effect on LPL activity in the functional pool suggests that IL-1 treatment might have influenced also the processing and/or transport of the enzyme to the cell surface.
When confluent cultures of 3T3 F442A cells were treated with insulin, differentiation occurred within 6 days as indicated by LPL secretion followed by increased intracellular levels of protein and triacylglycerol. PB increased LPL secretion 2- to 3-fold and intracellular LPL 3- to 10-fold in a time-dependent manner; these increments were less in proportion to the length of the time interval between confluence and initiation of PB treatment. These results are consistent with the notion that PB promotes conversion of adipocyte precursors to mature adipocytes by increasing the proportion of the former that become susceptible to the differentiating stimulus. Human subjects treated with heparin by continuous i.v. infusion over 4 days showed an initial decrease in serum triacylglycerol concentration in response to the initial bolus injection, accompanied by sharp increases in circulating LPL and HTGL, but the triacylglycerol concentration returned to normal within 24 hr. Rats infused with heparin by means of peritoneal implantation of osmotic minipumps demonstrated dose-dependent increases in circulating LPL, accompanied by reduction in heart muscle LPL but inconsistent changes in other tissues examined. Heparin had no effect on the clearance of circulating LPL but did reduce the total body pool of endothelial-bound enzyme. No changes in fasting triacylglycerol and free glycerol were observed, but exogenous VLDL were cleared at a faster rate in heparinized animals. Since the latter also manifested a decrease in de novo fatty acid synthesis, it seems that the heparinized rat is able to maintain circulating levels of triacylglycerol by efficient re-esterification of preformed fatty acids despite the enhanced lipolysis consequent upon higher plasma LPL activity.
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Endogenous apolipoprotein E in VLDL is poorly expressed in receptor binding processes. Yet catabolism of VLDL-remnants by cellular receptors depends on functional apo E molecules. To better understand remnant catabolism phenomena, we determined the metabolism of VLDL and post-lipolysis VLDL by cultured cells. Partial lipolysis was achieved by incubation of VLDL with lipoprotein lipase in vitro (human) or recirculation (rat) in supradiaphragmatic animals. Lipolyzed VLDL exhibit metabolic activities 2-20-fold higher than control VLDL, that are saturable and dependent on the presence of LDL receptors. The ligand responsible for receptor interaction of lipolyzed VLDL (apo E or apo B-100) and its source (endogenous or transferred) was studied with monoclonal antibodies and with lipoproteins from E-3/3 and E-2/2 subjects. The data unequivocally proved that lipolysis causes exposure of unreactive endogenous apo E-3 at the VLDL surface, possibly by a change of conformation of the protein. Apo B-100 becomes biologically expressed only in lipolyzed VLDL-III. Lipolyzed VLDL, however, is less reactive to exogenous apo E-3 than control VLDL indicating that endogenous and exogenous apo E are oriented differently in VLDL. It is proposed that VLDL delivers triglycerides to tissues when apo E is unreactive but becomes a remnant after the protein becomes exposed and directs the particles from lipoprotein lipase sites to cellular receptors.
Chronic heparin administration to rats for periods up to 8 days by i.p. implantation of mini pumps, increased serum total lipolytic activity in a dose-dependent manner up to infusion rates of 10 U/h per 100 g body weight. This augmentation was predominantly due to lipoprotein lipase (LPL). Synchronously, heart muscle demonstrated a dose-dependent reduction in LPL activity and adipose tissue showed a biphasic response, LPL activity decreasing at low doses and rising towards control levels at higher doses. Lipolytic activities of skeletal muscle and liver were unaffected. Increased serum LPL could not be attributed to altered enzyme clearance from the circulation in chronically heparinised rats, but was accompanied by a reduced response to i.v. high-dose heparin indicating reduction in the pool of endothelial-bound enzyme. Fasting serum concentrations of triacylglycerol and glycerol were unaffected in chronically heparinised animals although accelerated clearance of exogenous 14C-labelled VLDL was demonstrated, together with enhanced uptake of the isotope by liver and heart. Since de novo synthesis of fatty acids and triacylglycerol from 3H2O was not increased by heparin, we suggest that serum triacylglycerol concentrations were maintained by enhanced re-esterification of preformed fatty acids taken up by the liver. Hepatic cholesterol synthesis from 3H2O was augmented by heparin; this observation is consistent with reported increases in serum total and HDL-cholesterol mediated by chronic heparin administration in man and dog.
We have analyzed the binding of lipoprotein lipase (LPL) to the subendothelial extracellular matrix produced by cultured endothelial cells. Binding was linear up to a concentration of 0.5 microgram/ml (10 nM) enzyme used in this study, and equilibrium was achieved after 2 h of incubation with bovine 125I-LPL at 4 degrees C. Heparin and heparan sulfate effectively inhibited the binding of LPL to extracellular-matrix-coated plates; chondroitin sulfate had no effect, while high concentrations of dermatan sulfate or keratan sulfate inhibited binding of LPL to extracellular matrix by only 40%. Basic fibroblast growth factor (bFGF) did not affect LPL binding, while antithrombin-III (AT-III) caused up to a 50% inhibition of enzyme binding to extracellular matrix. alpha-Thrombin. 5.10(-6) M, and its esterolytically inactive derivative, DIP-alpha-thrombin, effectively inhibited binding of LPL to extracellular-matrix-coated plates. alpha-Thrombin was also able to release the extracellular-matrix-bound LPL in an active form. Extracellular-matrix-bound LPL detached into medium containing triolein emulsion and/or serum, and was catalytically active after being released. Extracellular-matrix-bound LPL lost 30% of its activity following incubation at 37 degrees C for 4 h. in contrast to soluble LPL which lost 75% of its activity. It is plausible to conclude from these data that in vivo the subendothelial basement membrane, similarly to extracellular matrix, sequesters and stabilizers LPL secreted into the subendothelial space by non-endothelial cells, and thus may play an important role in determining the route of LPL from its site of synthesis to its site of action.
An increased sensitivity of adrenalectomized (Adex) rats to intravenous (IV) injection of recombinant human tumor necrosis factor (rHuTNF) was manifested by a marked increase in the rate of mortality. The rats that died exhibited severe hypoglycemia and hypothermia. Administration of 2.5 or 10 micrograms/100 g body weight (3% or 12%) of the lethal dose in sham-operated rats (90 micrograms/100 g body weight) rHuTNF caused a mortality rate of 50% or 100%, respectively, within 4 hours of its injection. Pre-administration of dexamethasone or intermittent glucose infusion protected the animals from the lethal effect of rHuTNF. Indomethacin did not change the mortality rate in rHuTNF-treated Adex rats, but prevented it in sham-operated rats. The rats that died exhibited a marked decrease in body temperature, but only Adex rats developed hypoglycemia after low doses of TNF. Pretreatment with dexamethasone prevented the hypothermia in both Adex and sham-operated rats, while indomethacin was effective only in sham-operated rats and did not prevent the hypothermia or the hypoglycemia in Adex rats. In the surviving rHuTNF-treated Adex rats, a rapid increase in body temperature occurred, blood glucose decreased to 30 mg/dL, serum insulin concentration decreased to 6 microU/mL, liver glycogen content was reduced by 98%, and a significant reduction in liver phosphoeonolpyruvate carboxykinase (PEPCK) and liver microsomal glucose-6-phosphatase activities was observed. Repeated administration of glucose IV to rHuTNF-treated Adex rats caused an increase in blood glucose and insulin concentrations, and some repletion in liver glycogen content. Injection of rHuTNF, 2.5 to 10 micrograms/100 g body weight, to sham-operated rats caused a significant but slower increase in body temperature.(ABSTRACT TRUNCATED AT 250 WORDS)
Adipose tissue lipoprotein lipase was studied in smokers (n = 17) aged 18-47 years and compared with enzyme activity in non-smokers of comparable age (n = 8) and a second time in some of the subjects 5-9 weeks after cessation of smoking (n = 7). Serum cotinine levels served to validate the smoking status of the subjects. Fasting enzyme activity was similar in smokers and non-smokers, when expressed per 10(6) cells, but was significantly increased when normalized for cell size. When lipoprotein lipase was determined in the same individual 4 h after an oral glucose load, a significant decrease (P less than 0.002) occurred in the smokers, while enzyme activity rose in the nonsmokers (P less than 0.02). A tendency for enzyme activity to rise after oral glucose was seen in ex-smokers, which did not reach statistical significance. Even though the mean serum insulin and glucose levels did not differ in the three groups of subjects, the per cent decrease in lipoprotein lipase after oral glucose in smokers was negatively correlated with insulin release into serum in the same subject, i.e., the greater the insulin release, the less the decrease in lipoprotein lipase activity. We would like to propose that the lower body weight in smokers is related to the paradoxical response of adipose tissue lipoprotein lipase to carbohydrate and that the reversal of this behaviour contributes to the weight gain often observed after cessation of smoking.
Acenocoumarol sensitivity index (ASI) was calculated in 36 patients receiving amiodarone and acenocoumarol concomitantly, by dividing the acenocoumarol daily dose (micrograms kg-1 day-1) by the prothrombin ratio expressed as International Normalised Ratio (INR). It was found to be significantly lower (4.2 +/- 0.3 micrograms kg-1 day-1) than the ASI (11 +/- 0.6 micrograms kg-1 day-1) determined in 35 patients in the control group, who received acenocoumarol and not amiodarone. In 15 patients, ASI was 13.2 +/- 1.4 and 4.2 +/- 0.6 micrograms kg-1 day-1 before and after initiation of amiodarone therapy, respectively. In 5 patients, ASI was 6.2 +/- 0.6 micrograms kg-1 day-1, while patients were receiving both medications, and 28.1 +/- 6.1 micrograms kg-1 day-1 following discontinuation of amiodarone therapy. ASI determined while patients were on both medications was not affected by the presence of mild impaired renal or liver function. In 7 patients treated with both drugs concomitantly, severe bleeding diathesis developed. It is concluded that amiodarone augmented the anticoagulant effect of acenocoumarol in all patients receiving both drugs. An initial reduction of acenocoumarol daily dose by 50% and further adjustment of acenocoumarol dose according to daily prothrombin ratio is recommended. It is also suggested that acenocoumarol dose should be adjusted after cessation of amiodarone therapy.
The effect of phosphatidylinositol-specific phospholipase C (PI-PLC) on the release of lipoprotein lipase was studied in F1 heart cell cultures. Exposure of the cultures for 10 min to PI-PLC resulted in a 2-fold increase in the release of lipoprotein lipase (LPL) into the culture medium. PI-PLC released LPL from the heparin-releasable pool and PI-PLC was not effective in cultures pretreated with heparin. Insulin had no influence on the release of LPL from the heart cell cultures, even though it enhanced the uptake of 2-deoxy[3H]glucose by these cells. In cultures labeled with 35S, treatment with PI-PLC resulted in an increase in the release of 35S-labeled proteoglycan. PI-PLC was also effective in enhancing the release of bovine LPL exogenously bound to cultured aortic smooth muscle cells. The findings that PI-PLC was not effective after heparin, that it did release exogenously added LPL to cell cultures and that it released 35S-labeled proteoglycan, were interpreted to indicate that PI-PLC apparently acts on the release of LPL in an indirect manner, releasing heparan sulphate to which LPL is bound. As there is a previously described correlation between circulating LPL and the heparin-releasable LPL, we hypothesize that the activity of PI-PLC in the endothelial cell membrane or plasma phosphatidyl-specific phospholipase D regulates the plasma LPL levels.