ErbB4 alternative splicing mediates fetal mouse alveolar type II cell differentiation in vitro.

Background: Alternative splicing (AS) creates different protein isoforms, an important mechanism regulating cell-specific function. Little is known about AS in lung development, particularly in alveolar type II (ATII) cells. ErbB4 receptor isoforms Jma and Jmb have significant and opposing functions in the brain, heart, and lung development and/or disease.

ErbB4 is an upstream regulator of TTF-1 fetal mouse lung type II cell development in vitro.

TTF-1 is an important transcription factor in lung development and lung disease and is essential for lung cell differentiation, specifically surfactant protein (Sftp) expression. The molecular mechanisms that drive the expression and transcriptional control of TTF-1 are not fully understood. In the fetal lung, ErbB4 functions as a transcriptional co-factor and regulates the timely onset of fetal Sftp expression.

Partitioning of high-density lipoproteins in charge-sensitive two-phase systems.

Aqueous polymer two-phase systems characterized by a difference in the electrical potential between the upper and the lower phase (charged systems) are useful tools for the detection of changes in the surface charge and hydrophobicity of high-density lipoproteins (HDL). While the large particle size of low-density lipoproteins (LDL) leads to accumulation at the interface, the smaller diameter and the higher surface charge density of the native HDL particles allows partitioning without aggregation at the interface. Charged two-phase systems can be used to check the native state of HDL samples.

Quenching and dequenching of octadecyl Rhodamine B chloride fluorescence in Ca(2+)-induced fusion of phosphatidylserine vesicles: effects of poly(ethylene glycol).

Ca(2+)-induced fusion of SUV and LUV composed of ox brain phosphatidylserine (PS) was studied as a function of temperature and concentration of Ca2+ using octadecyl Rhodamine B chloride (R-18). Ca2+ was added to a 1:1 mixture of labelled (8 mol%) and unlabelled vesicles (assay conditions) or to samples containing only labelled liposomes (control conditions). Both, in SUV and LUV the dependence of differences in fluorescence between assay and control samples on temperature can be divided into three regions.

Partitioning of chemically modified low-density lipoprotein in aqueous polymer two-phase systems.

Aqueous polyethylene glycol (PEG)-dextran two-phase systems containing 10 mM Tris.HCl (pH 7.4) were used for the partitioning of chemically modified low-density lipoprotein (LDL).

[In vitro effects of low molecular weight dextran on the surface properties of LDL].

The relative number of free amino groups on the surface of low density lipoproteins (LDL) was determined after the incubation with low molecular weight dextran (MW 40,000) in several concentrations by two different assays (fluorescamine, TNBS). A decrease of the detectable free amino groups of 40% was shown by both assays. After the incubation of lysine with dextran these changes could not be observed.

Aggregation of human plasma high density lipoproteins induced by poly(ethylene glycol).

The influence of different surface charge densities (induced by varying pH, addition of positively charged amphiphilic molecules and chemical modification) of high density lipoproteins (isolated by ultracentrifugation) on poly(ethylene glycol) induced aggregation was studied. The effects of different molecular masses of PEG, HDL concentration and the presence of other serum proteins on the PEG mediated aggregation were investigated. The PEG concentration necessary for HDL aggregation is inversely proportional to the used HDL concentration and its molecular weight, and is directly proportional to the presence of other proteins and the magnitude of the negative surface charge density of HDL.

Modification of low density lipoproteins by sodium hypochlorite.

Human low density lipoproteins (LDL) were incubated with increasing amounts of sodium hypochlorite. A decrease of the number of free amino groups on the LDL surface starts only upon addition of 30-40 moles NaOCl per mole apoB, whereas all detectable SH groups are oxidized after addition of nearly 17-20 moles NaOCl. All hypochlorite-modified LDL samples have a higher electronegative surface charge compared with native LDL as revealed by agarose gel electrophoresis and partition of LDL in an aqueous polyethylene glycol/dextran two-phase system.

Partition of serum lipoproteins in a polyethylene glycol/dextran two-phase system.

Aqueous two-phase systems containing polyethylene glycol (PEG) and dextran as phase forming polymers were used for the partition of unmodified and hypochlorite modified lipoproteins. Low density lipoprotein (LDL) was separated from high density lipoprotein (HDL) by sequential ultracentrifugation from human plasma. In agreement with the higher electrophoretic mobility, high density lipoprotein shows a higher value of the partition coefficient in contrast to low density lipoprotein.

Characterization of chemical modifications of surface properties of low density lipoproteins.

Low density lipoproteins (LDL) were modified by incubation with formaldehyde and malondialdehyde and by autoxidation. Different methods were developed to measure alterations of surface properties of LDL. A method based on fluorescamine fluorescence was used to measure changes of free amino groups.

[Problems of photographic documentation of color patterns in connection with the use of thermography with liquid crystals (author's transl)].

Cholesteric liquid crystals show different colors dependent on their temperature. The "thermography with liquid crystals" makes use of this property for the determination of temperature distributions of human skin. The correct photographic documentation of the color patterns is difficult, because the colors depend on the angle of incidence of light and the direction of observation.