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  • 1
    ISSN: 0006-3592
    Keywords: lipase ; reverse micelles ; surfactants ; esterification ; glycerides ; kinetics ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The activity of purified Pseudomonas cepacia lipase has been investigated in esterification reactions of various aliphatic alcohols with natural fatty acids. The reactions were carried out in microemulsions formed in isooctane by bis-(2-ethylhexyl)sulfosuccinate sodium salt (AOT). Kinetic studies showed that the reaction follows a ping-pong bi-bi mechanism with inhibition by both substrates. The apparent kinetic parameters of the reaction were found to be Km octanol = 310 mM, Km lauric acid = 78 mM, and Vmax = 250 μmol min-1 mg-1. The same system was used for the synthesis of mono- and diglycerides from glycerol and lauric acid, which was successful at very low wo values. The catalytic behavior of P. cepacia lipase was also studied in esterification reactions performed in a nonionic microemulsion system formulated by tetraethyleneglycoldodecylether (C12E4). The optimum activity was found at about wo = 8. The apparent values of Vmax app and Km app for octanol were calculated and found to be 100 μmol min-1 mg-1 and 76 mM, respectively. © 1995 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Phytochemistry 23 (1984), S. 1325-1326 
    ISSN: 0031-9422
    Keywords: 4-hydroxymyoporone ; Athanasia grandiceps ; Convolvulaceae ; Fusarium solani ; Ipomoea batatas ; athanagrandione ; configuration ; eremoacetal. ; sesquiterpenoid ; sweet potato
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0031-9422
    Keywords: C"1"3 nor-isoprenoid ; Vitaceae ; Vitis vinifera ; actinidols. ; aroma volatiles ; distilled spirits ; grapes ; wines
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0378-4347
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0014-5793
    Keywords: (Na^+ + K^+)-ATPase ; (Neuroblastoma clone) ; Insulin ; Na^+ ; Pyrithiamine ; myo-Inositol uptake
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-0428
    Keywords: Keywords Non-insulin-dependent diabetes mellitus ; low density lipoprotein oxidation ; low density lipoprotein fatty acids ; lipid peroxidation ; conjugated dienes.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Oxidation of low density lipoprotein (LDL) plays an important role in the pathogenesis of atherosclerosis and is related to the fatty acid composition which is altered in diabetes mellitus. This study examines the relationship between the fatty acid composition of LDL and high density lipoprotein (HDL) and lipoprotein oxidation. A group of nine non-insulin-dependent diabetic (NIDDM) patients were compared to seven healthy control subjects before and after a high monounsaturated diet. Lipoproteins were isolated and oxidisability was measured by conjugated diene formation and lipid peroxide analysis. Serum HDL cholesterol was significantly lower in the diabetic patients. LDL cholesteryl ester linoleic acid in the diabetic patients was significantly higher at baseline and decreased after diet (p 〈 0.05) while oleic acid increased in both diabetic and non-diabetic subjects (p 〈 0.05). HDL cholesteryl ester oleic acid was lower in the diabetic patients compared with control subjects (p 〈 0.05) before diet and it increased significantly after diet (p 〈 0.05). LDL lipid peroxides and conjugated diene formation were related to LDL glycation (r = 0.46, p 〈 0.05 and r = 0.49, p 〈 0.05, respectively). Both decreased following diet (lipid peroxides for diabetic patients from 476 ± 30 to 390 ± 20 nmol/mg protein p 〈 0.05 and for control subjects from 350 ± 36 to 198 ± 30 nmol/mg protein p 〈 0.05). HDL conjugated diene formation decreased in both groups after diet but only significantly in the control group (55.4 ± 7.5 to 53.2 ± 6.7 nmol/mg protein for diabetic patients and 45.8 ± 6.4 to 31.6 ± 4.8 nmol/mg protein p 〈 0.05 for control subjects). There was a positive correlation between LDL lipid peroxide formation and percentage of cholesteryl ester linoleic acid in LDL from diabetic patients (r = 0.61, p 〈 0.05) and control subjects (r = 0.91, p 〈 0.01). Fatty acid composition of LDL was reflected in the composition of HDL. In the presence of HDL lipoprotein peroxidation decreased. This decrease in lipoprotein peroxidation was positively related to the percentage of linoleic acid in LDL (r = 0.71, p 〈 0.05). This study confirms the close relationship between the fatty acid composition of LDL and HDL and demonstrates the importance of the fatty acid composition of the cholesteryl ester fraction in relation to LDL oxidation in diabetes. Linoleic acid in HDL appears to be a protecting factor against oxidation. [Diabetologia (1996) 39: 667–676]
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-0428
    Keywords: Non-insulin-dependent diabetes mellitus ; low density lipoprotein oxidation ; low density lipoprotein fatty acids ; lipid peroxidation ; conjugated dienes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Oxidation of low density lipoprotein (LDL) plays an important role in the pathogenesis of atherosclerosis and is related to the fatty acid composition which is altered in diabetes mellitus. This study examines the relationship between the fatty acid composition of LDL and high density lipoprotein (HDL) and lipoprotein oxidation. A group of nine non-insulin-dependent diabetic (NIDDM) patients were compared to seven healthy control subjects before and after a high monounsaturated diet. Lipoproteins were isolated and oxidisability was measured by conjugated diene formation and lipid peroxide analysis. Serum HDL cholesterol was significantly lower in the diabetic patients. LDL cholesteryl ester linoleic acid in the diabetic patients was significantly higher at baseline and decreased after diet (p〈0.05) while oleic acid increased in both diabetic and non-diabetic subjects (p〈0.05). HDL cholesteryl ester oleic acid was lower in the diabetic patients compared with control subjects (p〈0.05) before diet and it increased significantly after diet (p〈0.05). LDL lipid peroxides and conjugated diene formation were related to LDL glycation (r=0.46, p〈0.05 and r=0.49, p〈0.05, respectively). Both decreased following diet (lipid peroxides for diabetic patients from 476±30 to 390±20 nmol/mg protein p〈0.05 and for control subjects from 350±36 to 198±30 nmol/mg protein p〈0.05). HDL conjugated diene formation decreased in both groups after diet but only significantly in the control group (55.4±7.5 to 53.2±6.7 nmol/mg protein for diabetic patients and 45.8±6.4 to 31.6±4.8 nmol/mg protein p〈0.05 for control subjects). There was a positive correlation between LDL lipid peroxide formation and percentage of cholesteryl ester linoleic acid in LDL from diabetic patients (r=0.61, p〈0.05) and control subjects (r=0.91, p〈0.01). Fatty acid composition of LDL was reflected in the composition of HDL. In the presence of HDL lipoprotein peroxidation decreased. This decrease in lipoprotein peroxidation was positively related to the percentage of linoleic acid in LDL (r=0.71, p〈0.05). This study confirms the close relationship between the fatty acid composition of LDL and HDL and demonstrates the importance of the fatty acid composition of the cholesteryl ester fraction in relation to LDL oxidation in diabetes. Linoleic acid in HDL appears to be a protecting factor against oxidation.
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  • 8
    ISSN: 1432-0428
    Keywords: Diabetic nephropathy ; albuminuria ; aldose reductase inhibitors ; prostaglandins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effect of two structurally unrelated aldose reductase inhibitors, sorbinil and ponalrestat, on glomerular prostaglandin production and urinary albumin excretion was investigated in rats with diabetes induced by streptozotocin. It was found that both aldose reductase inhibitors, when administered from the time of induction of the diabetes, significantly decreased the raised urinary albumin excretion in the diabetic rats, although it remained elevated compared with non-diabetic rats. Glomerular prostaglandin E and 6-ketoprostaglandin F1α production was significantly increased in glomeruli obtained from the diabetic rats. Inhibition of aldose reductase caused a reduction in the raised glomerular prostaglandin production, although this remained above that observed in the non-diabetic rats. Subsequent experiments were performed to determine whether the effects of the aldose reductase inhibitors could be explained by effects on glomerular filtration rate. It was found that ponalrestat, at a dose which markedly reduced urinary albumin excretion, did not significantly affect glomerular filtration rate in non-diabetic rats, rats with untreated streptozotocin-induced diabetes and rats with diabetes partially treated with low dose insulin. Glomerular sorbitol concentrations were significantly elevated in untreated diabetic rats as early as two weeks after the induction of diabetes. It is concluded that the administration of aldose reductase inhibitors from the time of induction of diabetes significantly reduces glomerular prostaglandin production and urinary albumin excretion. The latter effect is not due to an effect on glomerular filtration rate. Increased polyol pathway activity may account in part for the increased glomerular prostaglandin production and urinary albumin excretion in early experimental diabetes.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-0428
    Keywords: Non-insulin-dependent diabetes mellitus ; low-density lipoprotein oxidation ; dietary fatty acids ; low-density lipoprotein composition ; glycated low-density lipoprotein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The increased risk of atherosclerotic disease in diabetic subjects may be due to enhanced foam cell formation following an increased susceptibility of low density lipoprotein to oxidative modification. This study has compared fatty acid content and lipoprotein oxidisability in 10 non-insulin-dependent diabetic subjects with that in 10 control subjects. Both groups were normocholesterolaemic and the diabetic subjects had higher triglyceride levels (2.2±0.4 vs 1.2±0.2 mmol/l, p〈0.05). The fatty acid composition was compared in low density lipoprotein following Folch extraction, separation by thin layer chromatography (for the lipid classes) and analysis by gas liquid chromatography. Low density lipoprotein oxidisability was assessed by conjugated diene and thiobarbituric acid reacting substance formation in the presence of copper ions. The esterified/free cholesterol ratio was higher in the low density lipoprotein from patients compared to control subjects (2.9±0.1 vs 1.9±0.3, p〈0.05). Linoleic acid in the cholesteryl ester fraction of the lipoprotein was higher in the patients than in the control subjects (48.2±2.2% vs 42.4±3.4%, p〈0.05) as was the total quantity of linoleic acid in the cholesteryl ester fraction (317.8±68.0 vs 213.2±28.0 Μg/mg protein, p〈0.05) and in the low-density lipoprotein as a whole (443.2±70.0 vs 340.2±28.2 Μg/mg protein, p〈0.05). Lipoprotein oxidisability was also increased in the diabetic group with increased formation of thiobarbituric acid reacting substances (35.6±7.2 vs 22.3±3.5 nmol/mg protein, p〈0.05, increased total diene formation (502±60 vs 400±30 nmol/mg protein, p〈0.05) and increased rate of diene formation (7.2±0.6 vs 5.1±0.9 nmol diene · mg protein−1 · min−1, p〈0.05). This study indicates that low-density lipoprotein from diabetic subjects is more susceptible to oxidation. This could, in vivo, accelerate foam-cell formation thereby increasing atherosclerotic risk in diabetic subjects.
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  • 10
    ISSN: 1432-0428
    Keywords: Key words Non-insulin-dependent diabetes mellitus ; low-density lipoprotein oxidation ; dietary fatty acids ; low-density lipoprotein composition ; glycated low-density lipoprotein.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The increased risk of atherosclerotic disease in diabetic subjects may be due to enhanced foam cell formation following an increased susceptibility of low density lipoprotein to oxidative modification. This study has compared fatty acid content and lipoprotein oxidisability in 10 non-insulin-dependent diabetic subjects with that in 10 control subjects. Both groups were normocholesterolaemic and the diabetic subjects had higher triglyceride levels (2.2 ± 0.4 vs 1.2 ± 0.2 mmol/l, p 〈 0.05). The fatty acid composition was compared in low density lipoprotein following Folch extraction, separation by thin layer chromatography (for the lipid classes) and analysis by gas liquid chromatography. Low density lipoprotein oxidisability was assessed by conjugated diene and thiobarbituric acid reacting substance formation in the presence of copper ions. The esterified/free cholesterol ratio was higher in the low density lipoprotein from patients compared to control subjects (2.9 ± 0.1 vs 1.9 ± 0.3, p 〈 0.05). Linoleic acid in the cholesteryl ester fraction of the lipoprotein was higher in the patients than in the control subjects (48.2 ± 2.2 % vs 42.4 ± 3.4 %, p 〈 0.05) as was the total quantity of linoleic acid in the cholesteryl ester fraction (317.8 ± 68.0 vs 213.2 ± 28.0 μg/mg protein, p 〈 0.05) and in the low-density lipoprotein as a whole (443.2 ± 70.0 vs 340.2 ± 28.2 μg/mg protein, p 〈 0.05). Lipoprotein oxidisability was also increased in the diabetic group with increased formation of thiobarbituric acid reacting substances (35.6 ± 7.2 vs 22.3 ± 3.5 nmol/mg protein, p 〈 0.05, increased total diene formation (502 ± 60 vs 400 ± 30 nmol/mg protein, p 〈 0.05) and increased rate of diene formation (7.2 ± 0.6 vs 5.1 ± 0.9 nmol diene · mg protein–1· min–1, p 〈 0.05). This study indicates that low-density lipoprotein from diabetic subjects is more susceptible to oxidation. This could, in vivo, accelerate foam-cell formation thereby increasing atherosclerotic risk in diabetic subjects. [Diabetologia (1995) 38: 1300–1306]
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