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Biomedical subjects

W Krone

Publications and source records attributed to W Krone.

At least 163 records · Page 9Linked to original sources
PubMed1982

[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.e. to the structural alterations of the coding sequences. The repertory of possible alleles is further extended by the inclusion of regulatory sequences with a cis-dominant action. There are examples of the new concepts within the spectrum of multiple alleles causing various forms of thalassaemia. Our views on multiple allelism can no longer be based upon the paradigm of the classical gene. The concept of the functional unit provides a more promising approach.

Alleles↗
PubMed1982

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. This indicates that the catecholamines require some time to exert their inhibitory action on sterol synthesis. The action of catecholamines on the incorporation of [14C]acetate into sterols could be mimicked by dibutyryl cyclic AMP. Propranolol added in increasing concentrations to the incubation medium diminished or totally prevented the inhibitory effect of adrenaline, noradrenaline and isoproterenol on sterol synthesis. The results indicate that cholesterol synthesis in extrahepatic human cells, regulated predominantly by low density lipoprotein derived from plasma, is under additional control of catecholamines which may act via cyclic AMP.

Bucladesine↗
PubMed1981

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. The ratios of final to initial amounts of protein also differ significantly under both sets of growth conditions. High growth parameters occur significantly more frequently among our sample of 11 NF strains than among our sample of 13 control strains. The possibility of the expression of the NF genotype(s) on the level of the cultured fibroblast-like cells and the possible causes of the large ranges of inter- and intra-individual variations of the results are discussed.

Adolescent↗
PubMed1981

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. In fasted intact rats acute cold exposure lead to similar effects. A close parallelism between the rise in plasma glucagon and the concentration of hepatic cycloAMP was observed. Adrenalectomy did not impair the cold induced rise in plasma glucagon and hepatic cycloAMP. It is concluded that acute cold exposure caused a rapid rise in the concentration of plasma glucagon leading to an increase in the concentration of hepatic cycloAMP, thus enhancing the rate of hepatic gluconeogenesis and ketogenesis. As these alterations were similar in the absence of glucocorticoids and medulla-derived catecholamines, it is suggested that glucagon may play a role in the metabolic adaptation to acute cold exposure.

Adult↗
PubMed1980

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.

Animals↗
PubMed1980

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. Administration of cholestyramine resulted in a marked rise in the incorporation of [14C]acetate into sterols, while the administration of chenodeoxycholic acid did not significantly reduce basal sterol synthesis in normal subjects. These results demonstrate that in man the rate of sterol synthesis in intestinal mucosa is altered in response to physiological variables. Although these findings indicate that sterol synthesis in this tissue is subject to regulation, no difference was observed in basal sterol synthesis between normal subjects and patients heterozygous for familial hypercholesterolaemia.

Administration, Oral↗
PubMed1979

Regulation of sterol synthesis in human lymphocytes: evidence for post-transcriptional control by low density lipoprotein.

The effect of cordycepin (3'-deoxyadenosine), an inhibitor of messenger RNA synthesis, on the induction of 3-hydroxy-3-methylglutaryl coenzyme A reductase mediated by lipid-depleted serum was studied in isolated human lymphocytes. 50 micrograms/ml cordycepin, although inhibiting messenger RNA synthesis by more than 50%, had no inhibitory effect on the two and four-fold induction of hydroxymethylglutaryl-CoA reductase when cells were incubated in a medium containing lipid-depleted serum for 8 and 16 h, respectively. This result suggests that newly synthesises messenger RNA is not required for the effect of lipid-depleted serum on the induction of hydroxymethylglutaryl-CoA reductase in human lymphocytes.

Deoxyadenosines↗
PubMed1979

Partial trisomy for the long arm of chromosome 7 due to familial balanced translocation.

A partial trisomy for the distal segment of the long arm of chromosome 7 (bands q32 replaced by qter) was observed in a severely retarded child with somatic and CNS anomalies. The phenotypically normal father and paternal grandmother had a balanced reciprocal translocation between the long arm of a chromosome 2 and the long arm of a chromosome 7: 46,XX-XY,t(2;7) (q37;q32). The clinical features of the child at birth and at the ages of 5 months and 2 years are compared with those previously reported in cases of partial trisomy 7q.

Chromosomes, Human, 1-3↗
PubMed1979

Pattern of activity of nucleolus organizers during spermatogenesis in mammals as analyzed by silver-staining.

Silver-staining in the nuclei and chromosomes of spermatogenesis of four species of mammals (Man, Mus musculus, Rattus norvegicus, and Cavia cobaya) was investigated qualitatively and quantitatively. These species show a very similar pattern of activity of the nucleolus organizer regions (NORs) during the various stages of spermatogenesis. Silver precipitates are detectable in growing spermatogonia and up until the pachytene stage of meiotic prophase. During the meiotic metaphases I and II and during interkinesis silver-stainability disappears completely. A resumpton of silver-stainability occurs in round spermatids indicating a postmeiotic reactivation of NORs. This process does not persist beyond the early elongation phase. The quantitative determination of the silver-covered areas in relation to the total nuclear areas reveals minor differences between the species investigated with regard to the times and extents of maximum activation. The known localizations of the NORs in the karyotypes of the species investigated was confirmed using metaphase-preparations derived from somatic tissues.

Animals↗
PubMed1979

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. However, when these cells were incubated with cholesterol in a non-lipoprotein form suppression of sterol synthesis occurred as in normal leucocytes. These results suggest that leukaemic blast cells behave like cells from patients with familial hypercholesterolaemia in showing failure of regulation of sterol synthesis by low density lipoprotein.

Humans↗