MDR1, cholesterol certification and cell growth: a comparative study in normal and multidrug-resistant KB cell lines

The product of the MDR1 gene (P-gp) has been implicated in the transport of cholesterol from plasma membrane to endoplasmic reticulum for esterification. In previous studies on leukemia cell lines, we suggested that cholesterol esterification may regulate the rate of cell growth and that the MDR1 gene might be involved in this process by modulating intracellular cholesterol esters levels. To further investigate this matter, the rate of cell growth, cholesterol metabolism, expression of the MDR1 gene, and P-gp activity were compared in KB cell lines displaying differences in expression and function of P-gp (drug-sensitive phenotype versus MDR phenotype). The rate of cell growth correlated with cholesterol esterification in all KB cell lines, whereas the over-expression of MDR1 observed in the MDR cell lines was not always associated with an increased capacity of cells to esterify cholesterol. Two known inhibitors of P-gp activity, progesterone and verapamil, strongly inhibited both cholesterol esterification and cell proliferation in all KB cell lines, but they affected intracellular accumulation of labeled vinblastine only in MDR cell lines. These results further support a role for cholesterol esters in the regulation of cell growth and suggest that the P-gp expressed in MDR KB cells is not involved in the general process leading to cholesterol esterification. Received 14 February 2000; received after revision 10 April 2000; accepted 8 May 2000     

In vitro esterification of plant sterols by the esterifying enzyme of the small intestine of rat

Summary The in vitro esterification of plant sterols,-sitosterol, campesterol and stigmasterol, by the esterifying enzyme of the small intestine of rat was studied in the presence of saturated and unsaturated fatty acids. Campesterol esterification was highest, followed by sitosterol and stigmasterol irrespective of the type of fatty acid. Both campesterol and sitosterol esterification was greater with unsaturated fatty acids than with saturated fatty acids.Acknowledgments. Financed by the Emery Goff Research Award from the American Heart Association, Louisiana, Inc. and the USPHS research grant HL-08974 from the National Institutes of Health, Bethesda, Md.     

Séparation chromatographique de sucres méthylés isomères

Summary The qualitative and quantitative analysis of synthetic mixtures of non-isomeric and isomeric methylated glucoses, as present in the hydrolysate of methylated glucopolysaccharides, has been achieved by hydrogenation of the methylated sugars to the corresponding methylated hexitols, esterification withp-azobenzoylchlorid, and chromatographic analysis on activated alumina.     

Diterpene acids as larval growth inhibitors

Summary Kaurenoic and trachylobanoic acids from sunflower inhibited larval development in several Lepidoptera species. The tricyclic resin acids were also effective in curtailing growth ofPectinophora gossypiella and either reduction to carbinol or esterification of the carboxyl group lowered activity. Partial reversal of growth inhibition in the presence of relatively large amounts of cholesterol suggests an interaction with the insects' hormonal system.Acknowledgment. We wish to thankM. Rose andJ. Baker for insect bioassays.     

Competition between retinol and 3,4-didehydroretinol for esterification in crude pigment epithelial cell fractions

The membrane fraction of the retinal pigment epithelium (RPE) of the frog (Rana pipiens) catalyzed the esterification of tritiated retinol to retinyl esters. This esterification reaction was inhibited in the presence of 3,4-didehydroretinol.     

Opposite pattern of MDR1 and caveolin-1 gene expression in human atherosclerotic lesions and proliferating human smooth muscle cells

Cholesterol esterification and smooth muscle cell (SMC) proliferation are the crucial events in the development of atherosclerotic lesions. The objective of this study was to analyse cholesterol esterification and the expression of MDR1 (multidrug resistance), ACAT (acyl-CoA:cholesterol acyltransferase) and caveolin-1 genes in atherosclerotic and healthy vascular walls, in SMCs obtained from atherosclerotic lesions and saphenous veins. Results demonstrated higher levels of cholesterol esters, ACAT and MDR1 mRNAs and lower levels of caveolin-1 mRNA in atherosclerotic segments compared to adjacent serial sections of the same artery and the corresponding non-atherosclerotic arteries from cadaveric donors. SMCs isolated from atherosclerotic plaques manifested an increased capacity to esterify cholesterol and to grow at a faster rate than SMCs isolated from saphenous veins. In addition, when SMCs from atherosclerotic plaques were cultured in the presence of progesterone, a potent inhibitor of cholesterol esterification, significant growth suppression was observed. An increase in ACAT and MDR1 expression and a concomitant decrease in caveolin-1 expression were also observed in SMCs isolated from atherosclerotic arteries as early as 12 h after serum stimulation. An opposite pattern was found when SMCs were treated with progesterone. These findings support the idea that cholesterol esterification plays a role both in early atherogenesis and in clinical progression of advanced lesions and raise the possibility that the cholesterol ester pathway might directly modulate the proliferation of SMCs. Received 5 February 2001; received after revision 15 May 2001; accepted 15 May 2001     

Plasma lecithin: cholesterol acyltransferase activity in high-and low-responding rhesus monkeys

Summary The initial rate of esterification of plasma cholesterol by lecithin: cholesterol acyltransferase (LCAT) was measured in high- and low-responding rhesus monkeys fed a moderately high cholesterol (0.15 mg/kcal) diet. The results show that the rate of esterification of cholesterol in the plasma of the high-responders was significantly (p<0.025) higher than that of the low-responding animals. In view of known relationships between LCAT activity and plasma lipoprotein metabolism, it is suggested that the lipoprotein metabolism in the high-responders would differ from that in the low-responders.Acknowledgments. Financed by USPHS research grant HL-08974 from the National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Md.     

Cholesterol esterification activities in the intestines and pancreas of the albino rat

Summary Cholesterol esterification activities in intestines and pancreas are much greater with unsaturated fatty acids than with the saturated ones; the maximum activity is with arachidonic acid in intestines and with oleic acid in pancreas. The pancreatic cholesterol esterification activity is higher than the intestinal one.     

Labile protein-methyl ester: Comparison between chemically and enzymatically synthesized

Summary The rate of hydrolysis of protein-methyl ester, the enzymatic product of S-adenosylmethionine: proteincarboxyl methyltransferase (EC.2.1.1.24) acting on oxidized ribonuclease, was measured at pH 7.1 and 8.6 at 37°C. The half-life of the hydrolysis of the ester is 25 min at pH 7.1, and 4 min at 8.6. The rate of hydrolysis of the enzymatically formed esters at pH 7.0, in 0.1M phosphate buffer, was about 25 times faster than that of esters formed chemically by reaction with methanol in HCl. The lability of the enzymatically synthesized protein-methyl ester suggests that the esterification is specific to sites such that ionization of neighboring amino acid side chains enhances the rate of the hydrolysis.Acknowledgments. This work was supported by Research Grants AM 09603 from the National Institute of Arthritis and Metabolic Diseases, CA 10439 and CA 12226 from the National Cancer Institute, 1-P01-HD-05874 from the National Institute of Child Health and Human Development, National Institutes of Health, GM 20594-03 from National Institute of General Medical Sciences, USA.     

In vitro esterification of plant sterols by the esterifying enzyme of the small intestine of rat

The in vitro esterification of plant sterols, beta-sitosterol, campesterol and stigmasterol, by the esterifying enzyme of the small intestine of rat was studied in the presence of saturated and unsaturated fatty acids. Campesterol esterification was highest, followed by sitosterol and stigmasterol irrespective of the type of fatty acid. Both campesterol and sitosterol esterification was greater with unsaturated fatty acids than with saturated fatty acids.     

Cytologie comparée des Muridae. L'origine des Ellobii

Summary (1) The present paper deals with the chromosomial cytology of 11 species and underspecies ofMuridae. (2) The diploïd number being the same (2N=42), there are striking differences between two species ofBandicota, B. indica showing about 20 big metacentric chromosomes which are lackingB. bengalensis. (3)Meriones blackleri is characterized by 72 chromosomes, the species previously described possessing either 44 or 60 elements. (4) The study ofPhenacomys ungava confirms the view that 56 (54) is the primitive number in theMicroti. There is an interesting parallelism between the morphological and the cytological data. (5) A missing link betweenMicroti andEllobii has been found inMicrotus oregoni which possesses 17 chromosomes, its digamety belonging to the typeX-O, X-X. (6) Owing to the fact thatM. oregoni is more fossorial than the otherMicrotus, it is a morphological intermediate betweenMicroti andEllobii. (7) The genusChilotus (Baird) is also fully valid.     

Extreme temperatures reduce encapsulation of insect parasitoids in their insect hosts

Low (0°–4°C) and high (40°–48°C) temperatures to which two scales insects:Saissetia coffeae (Walker) andCoccus hesperidum L. (Homoptera: Coccidae) were subjected, before exposure to the encyrtidMetaphycus aff.stanleyi (Compere), reduced egg encapsulation of the parasitoid in the two hosts. Consequently the mass rearing ofM. aff.stanleyi was greatly improved.     

Un nouveau type de détermination chromosomique du sexe chez les mammifèresEllobius lutescens Th. etMicrotus (Chilotus) oregoni Bachm. (Muridés-Microtinés)

Summary (1)Ellobius lutescens andMicrotus oregoni show the same type of sex-chromosomes. The diploid number is odd in both sexes, seventeen.(2) The odd element ofEllobius is morphologically alike in the male and in the female. InM. oregoni, the odd element of the male is acrocentric, that of the female metacentric.(3) Following a hypothesis ofWhite, it seems very probable that the heterochromosome of the male is built of the primitiveY (short arm) and the primitiveX (long arm) linked together. In the female of the same species (M. oregoni), the sex-chromosome represents both theX fused together.(4) Only the half of the Zygotes may develope, the other half being lethal.(5) The close kinship betweenEllobius andM. oregoni is certain, a parallel evolution appearing as highly improbable.     

Cryo-bioorganic chemistry: freezing effect on stereoselection of l- and dl-leucine cooligomerization in aqueous solution

The chirality of l-/dl-leucine (50–50%) cooligomerization was investigated in liquid and frozen aqueous solutions. Cooligomerization was carried out by carbonyldiimidazole activation without initiator at an ambient (+22°C) and frozen (−18°C) temperature, respectively. The separated samples obtained after different time intervals of treatment were completely hydrolyzed (HCl) and the diastereomeric l- and d-leucine derivates of Marfey's reagent (1-fluoro-2,4-dinitrophenyl-5-l-alanine amide) were then traced and evaluated by RP-HPLC analysis. After 9 days of oligomerization, the l-Leu content was slightly enhanced in the liquid (57%) and somewhat more enhanced in the frozen (64%) samples. After 17 days, however, the l-Leu content had decreased in the liquid (53%) and frozen (56%) conditions. These l-enantiomer amplifications indicate that an l-antipode is preferentially incorporated into the α-helical turn of the oligomer in the earlier stage of cooligomerization, while, later, the d-antipode is also incorporated. The role of ice in the improved stereoselection is discussed. This is the first recorded example of the effect of freezing on stereoselection. Received 27 October 2000; revised 11 December 2000; accepted 4 January 2000     

Prediction of final data with use of preliminary and/or revised data

In the case of US national accounts the data are revised for the first few years and every decade, which implies that we do not really have the final data. In this paper we aim to predict the final data, using the preliminary data and/or the revised data. The following predictors are introduced and derived from a context of the non-linear filtering or smoothing problem, which are: (1) prediction of the final data of time t given the preliminary data up to time t- 1, (2) prediction of the final data of time t given the preliminary data up to time t, (3) prediction of the final data of time t given the preliminary data up to time T, (4) prediction of the final data of time t given the revised data up to time t -1 and the preliminary data up to time t- 1, and (5) prediction of the final data of time t given the revised data up to time t-1 and the preliminary data up to time t. It is shown that (5) is the best predictor but not too different from (3). The prediction problem is illustrated using US per capita consumption data.     

Forecasting with unbalanced panel data

This paper derives the best linear unbiased prediction (BLUP) for an unbalanced panel data model. Starting with a simple error component regression model with unbalanced panel data and random effects, it generalizes the BLUP derived by Taub (Journal of Econometrics, 1979, 10, 103–108) to unbalanced panels. Next it derives the BLUP for an unequally spaced panel data model with serial correlation of the AR(1) type in the remainder disturbances considered by Baltagi and Wu (Econometric Theory, 1999, 15, 814–823). This in turn extends the BLUP for a panel data model with AR(1) type remainder disturbances derived by Baltagi and Li (Journal of Forecasting, 1992, 11, 561–567) from the balanced to the unequally spaced panel data case. The derivations are easily implemented and reduce to tractable expressions using an extension of the Fuller and Battese (Journal of Econometrics, 1974, 2, 67–78) transformation from the balanced to the unbalanced panel data case.     

Field testing ofcis-11-tetradecenal as attractant or synergist in tortricinae

Summary Field studies have shown thatcis-11-tetradecenal is an effective attractant for maleChoristoneura conflictana, a pest of aspen. These studies also indicate thatcis-11-tetradecenal is probably a secondary component in the sex pheromone systems ofChoristoneura rosaceana andChoristoneura fumiferana.Christoneura conflictana (Wlk.),C. rosaceana (Harris) andC. fumiferana (Clemens) (Lepidoptera: Tortricidae: Tortricinae).Contribution No. IPRI 296.     

System-based weights versus series-specific weights in the combination of forecasts

System-based combination weights for series r/step-length h incorporate relative accuracy information from other forecast step-lengths for r and from other series for step-length h. Such weights are examined utilizing the West and Fullerton (1996) data set-4275 ex ante employment forecasts from structural simultaneous equation econometric models for 19 metropolitan areas at 10 quarterly step-lengths and a parallel set of 4275 ARIMA forecasts. The system-based weights yielded combined forecasts of higher average accuracy and lower risk of large inaccuracy than seven alternative strategies: (1) averaging; (2) relative MSE weights; (3) outperformance (per cent best) weights; (4) Bates and Granger (1969) optimal weights with a convexity constraint imposed; (5) unconstrained optimal weights; (6) select a ‘best’ method (ex ante) by series and; (7) experiment in the Bischoff (1989) sense and select either method (2) or (6) based on the outcome of e experiment. Accuracy gains of the system-based combination were concentrated at step-lengths two to five. Although alternative (5) was generally outperformed, none of the six other alternatives was systematically most accurate when evaluated relative to each other. This contrasts with Bischoff's (1989) results that held promise for an empirically applicable guideline to determine whether or not to combine.     

The in vitro characterization of the inhibition of mouse brain protein kinase-C by retinoids and their receptors

Summary The mechanism of the in vitro inhibition of Ca²⁺-, phosphatidylserine-dependent protein kinase C (PK-C)² by the purifiedholo (ligand-saturated) forms of cellular retinol-binding protein (cRBP) and cellular retinoic acid-binding protein (cRABP) was studied. We report here that i) the PK-C-inhibitory action ofholo-cRBP andholo-cRABP is due to their respective ligands, all-trans-retinol and all-trans-retinoic acid; ii) the reduced phosphorylation of theholo-retinoid-binding proteins and brain cytosolic proteins is not the result of a retinoid-induced soluble phosphatase or protease activity; iii) retinoids reduce PK-C affinity for calcium and phosphatidylserine in vitro; and iv) the structure-function activity of the retinoids and the specific interaction of these effect of retinoids on plasma membrane-associated PK-C activity pays a significant role in defining the early epigenetic aspects of PK-C-dependent tumor promotion and may be a physiological mechanism by which retinoids induce terminal differentiation in cell types that do not express soluble retinoid-binding proteins.We would like to thank Dr L.M. De Luca (NIH, USA) for his contribution of retinylphosphate, Dr H.N. Bhagavan (Hoffmann-La Roche) for his contribution of the arotinoids, and Merrill-Dow Corp. for their contribution of difluoromethylornithine. This work was supported by NIH Grants CA-34968, CA-07175, CA-22484, and CA-09020.     

Interconversion of T-2636 antibiotics produced byStreptomyces rochei var.volubilis

Zusammenfassung Mit angereicherten Enzympräparaten vonStreptomyces rochei var.volbulis sowie einigen Pilzen Hessen sich die Antibiotica T-2636 A (I) und D (III) zu C (II) beziehungsweise F (IV) reversibel desacetylieren. Die Antibiotica (III) und (IV) wurden auch mit dem EnzymS. rochei var.volubilis dehydriert.