The prostacyclin analogue iloprost and prostaglandin E1 suppress sterol synthesis in freshly isolated human mononuclear leukocytes.

The effects of the stable prostacyclin analogue iloprost, prostaglandin E1 and prostaglandin F2 alpha on sterol synthesis were investigated in freshly isolated human mononuclear leukocytes. Incubation of cells for 6 h in a medium containing lipid-depleted serum led to a 3-fold rise in the rate of sterol synthesis from [14C]acetate or tritiated water. Iloprost and prostaglandin E1 added in increasing concentrations at zero time resulted in an inhibition of the synthesis of sterols, the suppression being 50 and 55% at a concentration of 1 mumol/1, respectively.

Plasmid-determined cloacin DF13-susceptibility in Enterobacter cloacae and Klebsiella edwardsii; identification of the cloacin DF13/aerobactin outer membrane receptor proteins.

Both Enterobacter cloacae H478 and Klebsiella edwardsii S15 were shown to harbour a relatively large conjugative plasmid that coded for cloacin DF13-susceptibility and the production and uptake of a hydroxamate iron chelator, most probably aerobactin. Protein-blotting experiments with antiserum raised against the purified cloacin DF13/aerobactin receptor protein from Escherichia coli (Co1V-K30) revealed that the corresponding outer membrane receptor proteins of Ent. cloacae H478 and K.

Cell-culture studies on neurofibromatosis (von Recklinghausen's disease). III. Experiments on X-ray sensitivity.

The X-ray sensitivity of strains of fibroblast-like cells derived from peripheral neurofibromas of ten patients with neurofibromatosis was compared with that of 12 strains of skin fibroblasts derived from healthy donors. Quantitative parameters of the dose-dependent reduction in colony-forming ability did not differ significantly between these two groups of strains. The cloning efficiencies of nonirradiated controls varied within the same range in strains derived from patients and from healthy donors.

Stimulation of beta 2-adrenergic receptors suppresses sterol synthesis in human mononuclear leukocytes.

The beta-adrenergic receptor mediating the inhibition of sterol synthesis by catecholamines in freshly isolated human mononuclear leukocytes was defined pharmacologically by using selective beta 1- and beta 2-agonists and -antagonists. Incubation of cells for 6 h in a medium containing lipid-depleted serum resulted in a 3-fold increase in the incorporation of [14C]acetate or tritiated water into sterols. The beta-agonist (-)-isoproterenol was approximately equipotent with (-)-epinephrine and (-)-norepinephrine in suppressing sterol synthesis, yielding a sigmoidal log-dose-effect curve.

Evidence for post-transcriptional regulation by insulin of 3-hydroxy-3-methylglutaryl coenzyme A reductase and sterol synthesis in human mononuclear leucocytes.

Incubation of freshly isolated human mononuclear leucocytes in lipid-depleted serum for 4 h resulted in a two-fold increase in 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase activity. Insulin, when added to the incubation medium at concentrations of 10 and 100 nmol/l at zero time, caused additional increases in the enzyme activity of 30% and 37%, respectively. The hormone action was not immediate because no effect was observed when insulin was added at 4 h and activity examined thereafter.

[Antihypertensive therapy and lipid metabolism].

Hypertension, hyperlipidaemia and cigarette smoking are major risk factors in coronary heart disease. Since many antihypertensive drugs alter plasma lipid levels it is a subject of current discussion that these agents may increase associated coronary risk and therefore offset the beneficial effects of lowering blood pressure. The purpose of this paper is to review clinical and experimental data in the literature on the influence of data in the literature on the influence of antihypertensive drugs on lipid metabolism.

Subcloning of the cloacin DF13/aerobactin receptor protein and identification of a pColV-K30-determined polypeptide involved in ferric-aerobactin uptake.

A plasmid containing a pColV-K30 fragment that encoded only for the cloacin DF13/aerobactin receptor protein was constructed. Escherichia coli cells harboring this plasmid were sensitive to cloacin DF13 but were unable to take up ferric-aerobactin. Another pColV-K30-determined polypeptide (molecular weight, 50,000), localized in the membrane fraction, was essential for the uptake of ferric-aerobactin.

Cloning and expression of the cloacin DF13/aerobactin receptor of Escherichia coli (ColV-K30).

A DNA fragment derived from the ColV-K30 plasmid and coding for both sensitivity to cloacin DF13 and Fe3+-aerobactin uptake was cloned into pBR322. The cloned fragment coded for two polypeptides with molecular masses of 74,000 (the cloacin DF13/aerobactin receptor protein) and 50,000 daltons, respectively. When grown with sufficient iron, cells harboring pFS8 (with this fragment) possessed about 10 times as many receptor protein molecules as compared with cells of Escherichia coli (ColV-K30).

Cell culture studies on neurofibromatosis (von Recklinghausen). II. Occurrence of glial cells in primary cultures of peripheral neurofibromas.

The occurrence of glial cells in primary cultures established from peripheral neurofibromas of 18 patients with neurofibromatosis (von Recklinghausen) is described. The spindle-shaped cells can be distinguished from fibroblasts on the basis of morphological and ultrastructural criteria. As demonstrated by immunocytochemical analysis, the spindle cells express S-100 protein.

Effect of catecholamines on sterol synthesis in human mononuclear cells.

The effect of adrenaline, noradrenaline, isoproterenol and dibutyryl cyclic AMP on the rate of sterol synthesis was studied in freshly isolated human mononuclear cells. Incubation of cells in a medium containing lipid depleted serum led to a two-fold rise in the rate of sterol synthesis from [14C]acetate. Adrenaline, nor-adrenaline and isoproterenol added in a concentration of 2 X 10(-5) mol/l at zero-time resulted in an inhibition of 30% of this increase in sterol synthesis after 4 h, but had no effect when the hormones were given at 4 h.

[New aspects of the genetic heterogeneity of inborn errors of metabolism ].

New insight into the structure of eukaryotic genes on the one hand, and our knowledge of posttranslational protein modification and compartmentalization on the other, enable a more universal understanding of the genetic heterogeneity of inborn errors of metabolism. The fact that many genes are split into the coding exon-sequences and the non-coding intron-sequences necessitates the distinction of intron-alleles from exon-alleles. While intron-alleles affect the processing of the primary product of transcription, the exon-alleles correspond more or less to the classical alleles, i.

Cell culture studies on neurofibromatosis (von Recklinghausen). I. Comparative growth experiments with fibroblasts at high and low concentrations of fetal calf serum.

The growth of strains of fibroblasts derived from patients with neurofibromatosis (NF) was compared with that of strains from appropriate controls in culture medium containing 1% or 15% fetal calf serum. The means of the ratios of final to initial cell numbers do not differ significantly between NF strains and control strains. Weakly significant differences are, however, obtained after conversion of the results to mean numbers of cell population doublings, the NF strains showing the higher numbers.

Rapid rise in plasma glucagon induced by acute cold exposure in man and rat.

The effect of acute cold exposure on the concentration of glucagon in the blood was investigated in man and in intact and adrenalectomized rats. In man fasted overnight acute cold exposure, which caused a twofold increase in O2-consumption resulted in a rapid rise in plasma glucagon. The levels of insulin and blood glucose remained unaltered, while the concentration of serum free fatty acids and beta-hydroxybutyrate increased.

Regulation of sterol synthesis in human intestinal mucosa.

The effect of dietary factors and experimental manipulations designed to perturb the enterohepatic circulation on the rate of sterol synthesis were studied in freshly isolated human jejunal mucosa from normal subjects. Fasting significantly reduced the rate of sterol synthesis from [14C]acetate in jejunal mucosa obtained from normolipaemic obese subjects. A high cholesterol diet had no consistent effect on the synthesis in normal subjects.

Chemical studies on the silver staining of nucleoli.

The uptake of Ag-ions by isolated nucleoli of rat liver cells was studied. Nucleolar proteins separated by electrophoresis were examined for selective silver-staining. A mechanism for preferential Ag-staining of the nucleoli is discussed.

Regulation of sterol synthesis in leukaemic blast cells: a defect resembling familial hypercholesterolaemia.

Leucocytes from normal subjects and from patients with acute myeloblastic leukaemia incubated for 9 h in the absence of lipoproteins increased their rate of sterol biosynthesis from [2-14C]acetate threefold. Subsequent addition of complete serum, low density lipoprotein or cholesterol in a non-lipoprotein form suppressed sterol synthesis in leucocytes from normal subjects. In contrast, complete serum or low density lipoprotein totally failed to suppress sterol synthesis in leukaemic blast cells.

Deficiency of arginine and lysine causes increase in the frequency of sister chromatid exchanges.

An increase in the rate of sister chromatid exchanges (SCE) was found when V79 Chinese hamster cells were exposed to increasingly severe degrees of arginine and lysine deficiency. The data suggest a possible function of chromosomal proteins, and of histones in particular, in the maintenance of the low normal rate of SCE.