Conversion to docosahexaenoic acid-containing phosphatidylserine from squid skin lecithin by phospholipase D-mediated transphosphatidylation.

Phospholipase D (PLD)-mediated transphosphatidylation of squid skin lecithin with L-serine was examined to prepare docosahexaenoic acid-containing phosphatidylserine (DHA-PS). When a biphasic system with organic solvent and 0.2 M acetate buffer (pH 5.5) was used, PS synthesis was significantly affected by the amount of 3.4 M L-serine-containing acetate buffer. L-Serine concentration in the acetate buffer and choice of organic solvent were also crucial. In a typical reaction with 0.8 unit of PLD (Streptomyces sp.), 2.5 mL of ethyl acetate substrate solution containing 30 mg of squid skin lecithin in combination with 3 mL of 3.4 M L-serine-containing 0.2 M acetate buffer (pH 5.5), PS content in the recovered phospholipid fraction increased to 43.1% after 24 h. DHA composed 37.6% of fatty acids in the converted PS. This was the same DHA level as in the substrate. Phosphatidylcholine (squid skin PC, DHA 44.2%) in the squid skin lecithin was more effectively converted to PS than phosphatidylethanolamine.

Androgen-induced production of colony-stimulating factor (CSF) and colony-inhibitory factor (CIF) in the submandibular gland in female mice.

Both testosterone (T) and 5 alpha-dihydrotestosterone (DHT) significantly increased colony-stimulating factor (CSF) as well as colony-inhibitory factor (CIF) in the submandibular gland (SMG) in female mice. The CIF activity was completely inactivated by heating at 60 degrees C for 15 min, while the CSF activity was stable against the heat treatment. It was found that the CSFs obtained from the androgen-treated female mice and from normal male mice behaved identically in chromatography on hydroxylapatite and Ultro-gel AcA 34 columns. The potency of DHT to increase CSF activity was about 10 times greater than that of T.

Effect of macrophage colony-stimulating factor on the function of resident peritoneal macrophages.

Resident peritoneal cells of monocyte/macrophage lineage were collected by lavage of mice and incubated in vitro for 1-3 d in a culture medium containing various concentrations of macrophage colony-stimulating factor (M-CSF). Stimulation of the cells by zymosan showed that the potency of producing luminol-dependent chemiluminescence had been markedly increased in the CSF-treated cells, indicating increased generation of active oxygen species in these cells. There was an optimal concentration of M-CSF for the enhancement, and the potency of the cells was notably decreased by an overdose of M-CSF. The result was interpreted as being due to the down-regulation of M-CSF receptor.

Quantitation of apolipoprotein A-I in pooled human serum by single radial immunodiffusion and sodium dodecyl sulfate-polyacrylamide gel electrophoresis.

Apolipoprotein A-I was released from human HDL particles by treatment with 8 M urea, and the free apolipoprotein exhibited identical antigenicity and the same low mobility as purified apolipoprotein A-I in electrophoresis. Treatment of serum with 8 M urea enabled enabled quantitation of apolipoprotein A-I by single radial immunodiffusion assay, as judged by comparison with sodium dodecyl sulfate-polyacrylamide gel electrophoresis.

Modal-noise evaluation in multimode-fiber transmission.

Modal noise that occurs at fiber connecting points has been investigated theoretically and experimentally. Visibility, an important factor that determines the modal-noise power, has been obtained as a function of laser-diode (LD) coherency and fiber bandwidth. Modal-noise formulas, with such parameters as visibility, fiber-connection loss, and the number of modes that the fiber supports, are presented. Modal noise that is due to LD mode-partition noise is also discussed. The analytical results agree well with the experimnental ones.