Chinese hamster ovary cells expressing a novel type of acetylated low density lipoprotein receptor. Isolation and characterization

Macrophage scavenger receptors mediate the recognition of a wide range of negatively charged macromolecules including acetylated low density lipoproteins (AcLDL). Chinese hamster ovary (CHO) cells were cultured in the presence of increasing concentrations of simvastatin, a cholesterol biosynthesis inhibitor, and AcLDL as the sole source of exogenous lipoproteins. The cells surviving under these conditions specifically bound 125I-labeled AcLDL with high affinity and degraded them via an endocytic pathway. Unexpectedly, the association and degradation of 125I-labeled AcLDL by these CHO cells were not inhibited by dextran sulfate, fucoidan, and polyinosinic acid, competitors of macrophage scavenger receptors, but were completely inhibited by maleylated bovine serum albumin. Furthermore, these cells effectively took up negatively charged liposomes containing acidic phospholipids such as phosphatidylserine and phosphatidic acid, whereas CHO cells expressing macrophage scavenger receptors did not. AcLDL and negatively charged liposomes were cross-competed with each other. Northern blot analysis using the cDNA for the macrophage scavenger receptor revealed that these CHO cells did not express this receptor. From these observations, we conclude that the isolated CHO cells express a novel type of AcLDL receptor, which is distinct from macrophage scavenger receptors with respect to ligand specificity and competitor sensitivity.     

Protocol configuration and verification of an adaptive errorcontrol scheme over analog cellular networks

A high-speed and error-free voiceband data communication method using a hybrid automatic repeat request (ARQ) protocol over an analog cellular system is described. The present method adopts an adaptive error control scheme. This error control scheme automatically selects the optimal error correction code according to circuit bit error rate (BER), so as to match it to the frequently changing mobile radio propagation path conditions. This method adopts multiframe rejection as a retransmission scheme for a high throughput efficiency on the burst error circuit. Actual field evaluation was made by mounting this protocol on a CCITT V.22 bis modem with a data transmission speed of 2400 b/s and a modulation method using 16 carrier states over the Advanced Mobile Phone Service (AMPS) in Atlanta, GA, verifying that data communications can be achieved with an average throughput efficiency of 70% over a radio channel having a BER up to 10^-2     

Solvent extraction of metal ions using a new extractant,biuret(C8)

A new extractant biuret(C8) is synthesized and tested for solvent extraction of hard acid metals, for example, actinides, and soft acid metals. This compound has a central frame similar to that of malonamide but with an additional amino functional group introduced into the central framework; in this case, both the amidic oxygen atoms and the amino nitrogen atom may bond with metals. We found that both hard and soft acid metals can be extracted from nitric or perchloric acids to n-dodecane using biuret(C8). It is clear that D(Pd, Pu, U) values of approximately 100 can be obtained using 0.1 M biuret(C8)/n-dodecane.     

Thermotropic behavior of stratum corneum lipids containing a pseudo-ceramide

The mechanism of the self-assembly of the lamellar structure of natural stratum corneum lipids (SCL) has been a subject of considerable interest. We have examined this question by using a synthetic pseudo-ceramide (sphingolipid E, SLE) which was analogous to the naturally occurring ceramide type 2. The thermotropic properties and the structural characteristics of SLE, together with other main components of SCL, fatty acids, and cholesterol, were investigated by differential scanning calorimetry and X-ray analysis. A mixture of SLE and stearic acid was in a stable α-form having a lamellar structure, which is very similar to that of natural SCL. However, lipid mixtures in which stearic acid were replaced by oleic acid did not form lamellar structures, and existed in the crystalline states. This indicates that the stable bilayer formation of the natural SCL is strongly dependent on the molecular fatty acid structure. Moreover, incorporation of cholesterol (0–50%) into equimolar mixtures of SLE/stearic acid and of SLE/oleic acid caused a marked decrease of melting entropies, while the aggregation states of both systems were not changed. This effect of cholesterol can be attributed to the disorder of the molecular packing. These results suggest that the hydrophobic interactions between the SCL are important for bilayer formation as are the hydrophilic interactions between the polar groups.     

Solubility of butane and isobutane in molten polypropylene and polystyrene

The solubility of butane and isobutane in molten polypropylene (PP) and polystyrene (PS) was measured at pressures up to 3 MPa and along four isotherms from 438 to 483 K for PP and from 348 to 473 K for PS. The solubility increased with increasing pressure and decreasing temperature. At 438 K and 2 MPa, the solubilities of butane and isobutane in PP were 0.15 and 0.11 g‐gas/g‐polym, respectively. At 423 K and 2 MPa, the solubilities of butane and isobutane in PS were 0.08 and 0.05 g‐gas/g‐polym, respectively. Solubility could be correlated with the Sanchez‐Lacombe equation of state with temperature‐dependent binary interaction parameters to within 4.4% average relative deviation. Henry's constant for these gases in the PP and PS obtained in this work were used to determine correlation equations along with literature data. Polym. Eng. Sci. 44:2083–2089, 2004. © 2004 Society of Plastics Engineers.     

EFFECT OF DISTRIBUTOR ON BUBBLE SIZE AND BUBBLE RISE VELOCITY IN THE SLUGGING REGIME OF A SEMI-CYLINDRICAL GAS-SOLID FLUIDIZED BED†

A semi-cylindrical fluidized bed of 15 cm internal diameter, equipped with a transparent flat glass plate for the front wall, was employed to visually observe bubbles in the bubbling to slugging transition regime and in the slugging regime. Five kinds of perforated distributors were used to investigate the effect of distributor type on the bubble size and the bubble rise velocity. The average bubble size was not affected by distributor type in these flow regimes, and could be predicted by Darton et al's correlation (1974)of hole number 22. In other words, this comes from the inapplicability of the correlation to the slugging regime. The bubble rise velocity agreed well with Allahwala et al's correlation (1979) and was not affected by the type of distributor.     

Torrefaction of oil palm wastes

This paper describes the effect of torrefaction on the basic characteristics of agricultural biomass wastes in Malaysia, such as empty fruit bunches (EFB), mesocarp fiber and kernel shell as a potential source of solid fuel. Mesocarp fiber and kernel shell exhibited excellent energy yield values higher than 95%. EFB, on the other hand, exhibited a rather poor yield of 56%.     

Efficient intraliposomal entrapment of hydrophilic platinum oligonuclear complexes

A simple method for intraliposomal entrapment of platinum complexes is presented, where hydrophilic platinum oligonuclear complexes, 1-methyluracil green (MeUG), uridine green (UdG) and uridine blue (UdB), are included inside liposomes and allowed to react with bilayer lipids. The liposomes prepared in this method exhibit higher entrapment efficiency and higher distribution to organs (liver, kidney, spleen, lung) and blood (but not B16 cancer cells) than those prepared from mononuclear Pt complexes [cis-diamminedichloroplatinum, cis-diammine-1,1′-dicarboxylatocyclobutaneplatinum, and cis-dichloro-cis-dihydroxy-trans-bis(isopropylamine)platinum)].