Uniform preparations of large unilamellar vesicles containing anionic lipids

A general procedure for the preparation of large unilamellar vesicles of selected sizes has been developed. The procedure consists of dissolving the lipid in organic solvent, washing with mild acid, removing the solvent, adding salt (0.15 M KCl) solution, and adjusting the pH (raising it to about pH 10 and lowering it immediately to pH 7.55). The procedure takes less than 30 min. The resulting unilamellar vesicles are of a single size with a rather low standard deviation. The sizes of these preparations range between 150 and 1000 nm in diameter. Sizes and polydispersities were measured to within 1-2% by photon correlation spectroscopy. Vesicle size varies with the phospholipid structure, the composition of the phospholipid mixture, the ionic strength of the medium, the alkyl chain composition, the cholesterol content of the phospholipid mixture, and the timing of the pH adjustment procedure. Uniform preparations of vesicles have been obtained from the dioleoyl esters of phosphatidic acid, phosphatidylglycerol, phosphatidylethanolamine, and phosphatidylserine, from diphytanyl ethers of glycolipid sulfate, phosphatidylglycerol, phosphatidylglycerol phosphate, and phosphatidylglycerol sulfate, from bovine liver phosphatidylinositol, from Escherichia coli phosphatidylethanolamine, from membrane lipid extracts from E. coli and Holabacterium cutirubrum, and from dodecanesulfonate-alkanol mixtures and free oleic acid. The preparation of unilamellar vesicles from oleic acid is novel, and the size range is 600-3000 nm; the preparations are relatively uniform. Vesicles of phospholipids in which sucrose and trehalose replace salt as the impermeant do not differ significantly from those prepared in pentaerythritol.

Influence of passive smoking on admissions for respiratory illness in early childhood

An association was sought between passive smoking and inpatient admissions for respiratory illness in 1058 children born between 1 June and 31 December 1981 and living in the neighborhoods of Nan-Jing Western Road and Yan-An Western Road in Jing-An District, Shanghai. The admission rate for first episodes of respiratory illness was positively correlated with the total daily cigarette consumption of family members during the children's first 18 months of life. The relative risk of developing a first episode of respiratory illness was 1.80 for children living in families including people who smoked 10 or more cigarettes a day compared with those living in non-smoking families. Multiple logistic regression analysis showed that the effect of passive smoking on inpatient admission for respiratory illness was independent of the child's birth weight, type of feeding, father's education, size of the home, and chronic respiratory disease among adults in the family. The adjusted odds ratios compared with the non-smoking group were 1.17 in families smoking 1.9 cigarettes daily and 1.89 in families smoking 10 or more cigarettes daily. These data suggest that exposure to household cigarette smoke of children in early life increases the risk of severe respiratory illness.

Ascorbate regeneration in bovine ocular tissues by NADH-dependent semidehydroascorbate reductase

Despite its fast autoxidation in vitro, ascorbate remains in its reduced form in vivo, indicating a special mechanism may be involved in its regeneration. The presence of an NADH-dependent reductase system, semidehydroascorbate reductase (SDR), for regeneration of ascorbate from its partially oxidized form, semidehydroascorbate (SDA), was demonstrated in bovine ocular tissues after extraction in Triton X-100. Highest SDR activity was detected in retinal extracts in the order of retina greater than pigment epithelium-choroid = ciliary body greater than iris. Minimal or no activity was observed in lens extracts or in aqueous fluid. Freezing and thawing, or boiling, destroyed the NADH-dependent SDR activity. NADH oxidation was significantly reduced (22% of total activity) when assays with retinal extracts were performed at 5 degrees C. Treatment with 4 mM, N-ethylmaleimide reduced the rate of NADH oxidation to 73 or 42% compared with control values with retinal or ciliary body extracts, respectively.

Non-competitive inhibition of myo-inositol transport in cultured bovine retinal capillary pericytes by glucose and reversal by Sorbinil

myo-Inositol transport by retinal capillary pericytes in culture was characterized. The major myo-inositol transport process was sodium-dependent, ouabain-sensitive, and saturable at 40 mM, indicating a carrier-mediated process. The sodium ion concentration required to produce one-half the maximal rate of myo-inositol uptake ([Na+]0.5) did not show dependence on the external myo-inositol concentration (22.3 mM sodium for 0.005 mM myo-inositol; 18.2 mM sodium for 0.05 mM myo-inositol). myo-Inositol transport was an energy-dependent, active process functioning against a myo-inositol concentration gradient. The kinetics of the sodium-dependent system fitted a 'velocity type' co-transport model where binding of sodium ion to the carrier increased the velocity (Vmax 28 to 313 pmol myo-inositol/micrograms DNA per 20 min when [Na+] varied from 9 to 150 mM) but not the affinity for myo-inositol (Km 0.92 to 0.83 mM when [Na+] varied from 9 to 150 mM). Metabolizable hexoses (D-glucose or D-galactose; greater than 5 mM) inhibited myo-inositol uptake. Dixon-plot analysis indicated that the inhibition was non-competitive with a Ki of 22.7 mM for D-glucose and 72.6 mM for D-galactose. The inhibition was significantly reversed by Sorbinil (0.1 mM), an aldose reductase inhibitor. In contrast, high concentrations of non-metabolizable hexoses (L-glucose, 3-O-methyl-D-glucose), or partially metabolizable 2-deoxy-D-glucose, did not significantly inhibit myo-inositol uptake. The inhibitory effect of D-glucose or D-galactose on myo-inositol transport appeared to be related to glucose or galactose metabolism via the polyol pathway.

Monoclonal antibody detection of transformation associated protein (TAP) in ts110 Moloney murine sarcoma virus transformed 6M2 cells that are different from the mos gene product

By the use of a highly specific monoclonal antibody (designated MC), we were able to detect three radiolabeled bands with molecular weights of 60,000, 63,000, and 66,000 daltons in the ts-110 Moloney murine sarcoma virus mutant-transformed rat kidney cells known as 6M2. Expression of transformation properties as well as these three bands in 6M2 cells was found to be temperature sensitive. Therefore, MC detected factors that are apparently associated with the transformation of 6M2 cells. These factors are tentatively referred to as transformation associated proteins. These transformation proteins were found in two other Moloney murine sarcoma virus-transformed rat cell lines. These proteins were found to differ from known gene products of the ts-110 Moloney murine sarcoma virus mutant and do not have kinase activity. The transformation associated proteins may represent rat cellular factors activated during the transformation of rat cells by Moloney murine sarcoma virus.

Sensory and behavioral effects of gossyplure alcohol on sex pheromone response of male pink bollworm moths,Pectinophora gossypiella

(Z,Z)- and (Z,E)-7,11-hexadecadienol, reported to be pheromone precursors, interfere with the normal sequence of behavioral response of malePectinophora gossypiella to sex pheromone. The magnitude of the interference can be diminished with higher release rates of the sex pheromone. (Z,Z)-7,11-Hexadecadienol is more effective than itsZ,E isomer in eliciting the reduction in the behavioral response. Electroantennographic evidence suggests that each alcohol may be interfering more with receptor sites for the conformationally similar pheromone acetate than with receptor sites for the other pheromone isomer. Defining behavioral and physiological effects of pheromone analogs such as the alcohols of gossyplure may help to determine their potential for behavioral manipulations.

Preparation and characterization of monodisperse unilamellar phospholipid vesicles with selected diameters of from 300 to 600 nm

A method has been developed for making large unilamellar vesicles (LUV) with low polydispersity. The LUV, constituted of dioleoylphosphatidic acid (DOPA), 300 nm in diameter are made by a modification of the pH adjustment technique (Hauser, H. and Gains, N. (1982) Proc. Natl. Acad. Sci. USA 79, 1683-1687). This size is 10 times that (30 nm) of vesicles prepared by prolonged sonication. Vesicle size is increased stepwise by adding cholesterol (to a maximum of 40 mol% cholesterol) to form vesicles in 0.15 M KCl with up to 600 nm diameter. The vesicle size is measured by photon correlation spectroscopy, electron microscopy, and by measurement of the internal volume with cyanocobalamin while calculating the number of DOPA molecules per vesicle. Vesicles are stable for at least three weeks. Sepharose 4B column chromatography of the preparation yields a peak of fractions with the same polydispersity as the original sample and shows that 30 to 40% of the original lipid in a sample is recovered as LUV. Less than 2% of the sample forms small unilamellar vesicles (SUV) (diameter = 30 nm), which emerge from the column in a separate peak. Since the remaining lipid is not suspended in the buffer during vesicle formation, for most purposes the vesicles may be used immediately after titration so that they can be prepared in less than 40 min.

Characterization of glucose transport by bovine retinal capillary pericytes in culture

The transport of D-glucose and its non-metabolizable analog, 3-o-methyl-D-glucose (3-o-MG), by cultured bovine retinal capillary pericytes was characterized. A preference for D-glucose over L-glucose uptake by pericytes indicated a stereospecific process. The 3-o-MG transport appeared to follow complex kinetics. At low substrate concentrations, 3-o-MG transport had an apparent Km of 1.53 mM and a Vmax of 0.50 nmol (microgram DNA)-1 min-1 at 37 degrees C. A reduced extracellular sodium concentration, energy poisons, and exogenous insulin did not significantly influence 3-o-MG uptake. Inhibition of the uptake or efflux of 3-o-MG by cytochalasin B or phloretin, respectively, and the demonstration of a 'counter transport' phenomenon showed that 3-o-MG transport by retinal capillary pericytes in culture was a carrier-mediated process.

Monitoring the arbitrary thickness of optical thin films and their error simulation: a method

This paper was the method of monitoring the absolute value for film layer transmittance to monitor the thickness of optical thin film. For this purpose, a 2S3G double-color three-path monitoring apparatus was built. Simulation analyses of monitoring errors have been conducted and a flow diagram is given. Using this method and apparatus, 9-, 15-, and 23-layer broadband neutral dichroic filters, cold light coatings, edge filters, and polarizers have been plated; good reproducibility and satisfactory results have been obtained, thereby achieving the preparation of the non-lambda/4 multilayer system

The effects of glucose and an aldose reductase inhibitor on the sorbitol content and collagen synthesis of bovine retinal capillary pericytes in culture

The absolute rate of collagen synthesis by cultured bovine retinal capillary pericytes, determined using the specific radioactivity of proline in the cellular amino acid pool, was compared in media containing different concentrations of glucose (5, 10 or 40 mM) and Sorbinil (0.0 or 0.1 mM), an inhibitor of aldose reductase. The absolute rate of collagen synthesis, in proline molar terms, by pericytes in medium with 5 mM glucose was 3.3 +/- 1.9 (S.D.) pmol 10(-7) cells 24 hr-1, and increased significantly to 8.8 +/- 3.7 pmol 10(-7) cells 24 hr-1 when the glucose concentration was increased to 40 mM. Sorbinil (0.1 mM) reduced the elevated sorbitol contents of pericytes induced by high concentrations of glucose, but did not significantly change the absolute rate of collagen synthesis per cell.

T and B cells induce macrophages which suppress proliferation but not lymphokine secretion

In vitro culture of mouse spleen cells for 2 days or more leads to the production of adherent, phagocytic, Thy-1-, Ia+, Lyt-2- cells ("suppressor macrophages") which strongly inhibit the proliferative response of T and B lymphocytes to a variety of stimuli: mitogens, specific antigens, and antigen-nonspecific growth factors. Suppressive activity fails to develop, however, in cultured spleen cells from which nonadherent cells have been removed before the initial 48-hr incubation, and only partial suppression is obtained from cell suspensions from which T cells have been depleted before culture. We find that the requirement for nonadherent cells can be replaced by graded doses of lymphocytes. Lyt-2- and Lyt-2+ T cells are about equally potent in inducing suppressive activity in nonadherent cells. Surprisingly, B cells (containing fewer than 0.1% contaminating T cells) are also able to induce suppression in this system. The suppression induced includes both indomethacin-sensitive and indomethacin-resistant components. Interestingly, not all stages of mitogen-induced T-cell activation are blocked by these adherent cells: proliferation is inhibited, but production of interleukin 2 (IL-2) and interleukin 3 (IL-3) is unaffected.

Nonenzymatic glycosylation of bovine retinal microvessel basement membranes in vitro. Kinetic analysis and inhibition by aspirin

Incubation of intact bovine retinal microvessels or isolated retinal microvessel basement membranes (RVBM) with radioactive D-glucose or L-glucose, followed by basement membrane collagenous protein purification, resulted in the isolation of nonenzymatically glycosylated RVBM collagens. Type IV collagen was identified in the RVBM by selective salt fractionation, SDS-polyacrylamide gel electrophoresis, amino acid analysis, and immunoprecipitation with specific antibody. Kinetic analysis of the condensation of glucose with RVBM was carried out by labeling retinal microvessel basement membranes with D-[2-3 H]-glucose and D-[6-14 C]-glucose. The rate constant for aldimine product formation, k1, was 1.95 +/- 0.24 (SD) X 10(-4) mM-1 h-1, and the rate constant for the reversed reaction, k-1, was 5.9 +/- 1.0 X 10(-2) h-1. Based on a rate constant for the Amadori rearrangement, k2, of 8.8 +/- 1.0 X 10(-3) h-1, which was the rate-determining step, the half life of this reaction was 80 +/- 9 h. These data may be useful in estimating the glycosylation of retinal microvessel basement membranes in vivo. The nonenzymatic glycosylation of retinal microvessel basement membrane proteins was progressively inhibited by increasing concentrations (0.1 to 2.0 mM) of aspirin.

Stimulation of retinal capillary pericyte protein and collagen synthesis in culture by high-glucose concentration

The influence of glucose concentration on cell multiplication and protein synthesis was studied in synchronized, long-term cultures of bovine retinal microvessel pericytes. The cell multiplication rate and the mitotic rate were reduced in media containing 20 mM glucose to 57% and 54%, respectively, of that obtained in media containing 5 mM glucose. Elevated glucose, however, did not change the DNA content of individual cells. Protein and collagen synthesis were measured by the incorporation of radioactive proline and lysine, or the posttranslational production of hydroxyproline and hydroxylysine, respectively. High glucose stimulated protein and collagen synthesis per cell 2.2 +/- 0.10 (SD) and 2.1 +/- 0.06 times, respectively. Aspirin (0.5 mM), an inhibitor of nonenzymatic glycosylation, did not alter the effect of elevated glucose concentration on protein and collagen synthesis.

Extracellular matrix production by cat retinal pigment epithelium in vitro: characterization of type IV collagen synthesis

Feline retinal pigment epithelial cells (RPE) produced an extracellular matrix (ECM) in vitro which was located between the basal surface of the RPE and the culture plate. This ECM had three morphological components: bundle, granular and fibrillar. After 14 days in culture the basal extracellular space contained small amounts of bundle material; granular and fibrillar material were infrequently observed at this time. The amount of ECM material increased with increasing time in culture. The accumulation of the granular component extracellularly was greatest between 60 and 108 days. Fibrillar material, although occasionally observed in the ECM, appeared to be an infrequent component. By 145 days, the ECM filled the extracellular space between the RPE and the culture plate. The time-dependent increase of the ECM indicated continued synthesis and secretion of ECM into the basal extracellular space by the RPE. Confluent RPE cultures, or choroidal/scleral fibroblasts, were incubated for 24 hr with [14C]-proline. Newly synthesized collagen, either in the culture medium or the cell layer, was co-precipitated with added carrier collagen by (NH4)2 SO4. The samples, with or without reduction and alkylation, were digested with pepsin and fractioned by selective salt precipitation and carboxymethyl(CM)-cellulose chromatography. The resulting fractions were further analyzed, or purified for thin layer chromatography (TLC) amino acid analysis, by SDS-polyacrylamide gel electrophoresis (SDS-PAGE). Cultured RPE cells, but not choroidal/scleral fibroblasts, produced labelled peptides which were characterized as alpha 1 (IV), and alpha 2 (IV) collagen chains by CM-cellulose chromatography, SDS-PAGE, proline: hydroxyproline ratios and sensitivity to bacterial collagenase. In contrast, choroidal/scleral fibroblasts produced labelled alpha 1 (I), beta 12 (I) and alpha 2 (I) collagen chains. The synthesis of type IV collagen by RPE cells may reflect the production of ECM observed by electron microscopy in cultured feline RPE cells.

Binding of fluorescein and carboxyfluorescein by human serum proteins: significance of kinetic and equilibrium parameters of association in ocular fluorometric studies

The binding of fluorescein and 5- and 6-carboxyfluorescein by human serum proteins was measured at 37 and 4 degrees C by equilibrium dialysis. The equilibrium association constants (KA) for fluorescein were 3.7 X 10(3) and 7.1 X 10(3)M-1, and for carboxyfluorescein were 3.5 X 10(3) and 7.5 X 10(3)M-1 at 37 and 4 degrees C equilibrium dialysis data, was 3.9 X 10(3) binding sites in human serum, determined from the 37 degrees C equilibrium dialysis data, was 3.9 X 10(-3)M for fluorescein and 3.3 X 10(-3)M for carboxyfluorescein. Utilizing these binding parameters it was calculated that a maximum of 93.5% of the total fluorescein and 92.0% of the carboxyfluorescein would be bound by undiluted human serum proteins at 37 degrees C. Experimental binding data obtained after prolonged equilibrium dialysis (four days) at low total fluorochrome concentrations (1.5 X 10(-4)M or less) indicated that 93.1 +/- 1.0 (S.D.)% of the fluorescein and 90.1 +/- 0.7% of the carboxyfluorescein were bound at 37 degrees C by undiluted human serum proteins. Stopped-flow kinetic spectrophotometric studies of the changes in absorptivity at 487-488 and 510 nm that occurred when the fluorochromes were bound by human serum proteins, indicated that the fluorescein and carboxyfluorescein binding reactions were 99% complete within 0.65 and 1.72 sec. These had second-order association rate constants at 25 degrees C of 3.0 X 10(3) and 1.5 X 10(3)M-1 sec-1, respectively. These findings offer a basis for calculation of bound and free fluorescein and carboxyfluorescein in vivo in human subjects.