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I Müller

Publications and source records attributed to I Müller.

At least 199 records · Page 11Linked to original sources
PubMed1978

Species-specific aggregation factor in sponges. VII. Its effect on cyclic amp and cyclic gmp metabolism in cells of Geodia cydonium.

In dissociated single cells from the sponge Geodia cydonium, DNA synthesis is initiated after incubation with a homologous, soluble aggregation factor. During the DNA-initiation phase the cyclic AMP- and cyclic GMP levels vary drastically; the cyclic AMP content drops from 2.2 pmol/10(6) cells to 0.3 pmol/10(6) cells while the cyclic GMP content increases from 0.6 pmol to 3.7 pmol/10(6) cells. The activity of neither the adenylate cyclase nor of the guanylate cyclase isolated from cells which have been incubated for different periods of time with the aggregation factor, is changed. The soluble as well as the particulate enzyme activities were checked in vitro. The cyclic nucleotide receptors have been isolated from the sponge cells and characterized with respect to their molecular weight, dissociation constant for cyclic AMP or cyclic GMP and intracellular concentration. None of these parameters are altered during aggregation factor-mediated DNA initiation. From these data it is concluded that the regulation of cyclic nucleotide levels is a consequence of a changed activity of nucleotide cyclases or of phosphodiesterases, but this is presumably not caused by a changed rate of synthesis of nucleotide cyclases or of cyclic nucleotide receptors.

Adenylyl Cyclases↗
PubMed1978

[Hydrocephalus].

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Child↗
PubMed1978

[Behavior of various blood constituents (glucose, fructose, insulin, lactate, pyruvate, free fatty acids, inorganic phosphate) and half-life of monosaccharides in the plasma after i.v. infusion of glucose, fructose, galactose and invert sugar solutions in ruminants. 1. Studies in calves and heifers].

Studies into the half-life of monosaccharides as well as into the effects of intravenous infusion of sugar solutions (0.5 g/kg body weight of glucose, fructose, galactose, and invert sugar) on the concentration of various blood components were undertaken with six calves and five heads of young cattle. Half-life values of glucose and galactose were of nearly identical magnitude over the first weeks of age, whereas that of fructose was much longer on account of slower conversion. Infusion of invert sugar solution, therefore, cannot be recommended for calves during the first three weeks of age. Infusion of the above monosaccharides led to more or less strongly pronounced rise of insulin levels in the blood serum. More or less strongly marked pyruvate increase took place following infusion, if the pyruvate concentration in the blood plasma had been low before infusion. Lactate levels in the blood usually underwent little change, whereas the levels of free fatty acids and inorganic phosphate in the blood plasma usually were reduced.

Animals↗
PubMed1978

[Behavior of various blood constituents (glucose, fructose, insulin, lactate, pyruvate, free fatty acids, inorganic phosphate) and half-life of monosaccharides in the plasma after i.v. infusion of glucose, fructose, galactose and invert sugar solutions in ruminants. 2. Studies in cattle].

Monosaccharides were intravenously injected to eight adult heads of cattle, between 380 kg and 670 kg in live weight, to study, in the context of stress endurance, the half-life values of the sugars as well as monosaccharide effects upon concentrations of various blood components. The fructose concentration in the blood plasma went up temporarily following the infusion of glucose solution. Fructose infusion usually caused only little rise of the glucose concentration in blood plasma, with hypoglycaemia occurring quite often towards the end of an experimental period. The half-life values of sugar in blood plasma were between twelve and 29 and those of fructose between ten and 17 minutes. The rate of fructose conversion was higher than that of glucose conversion, but values were identical in some cases. The pyruvate concentration in the blood and the insulin level in blood plasma went up in response to infusion of monosaccharide solutions. Urine excretion of monosaccharides following invert sugar infusion was less than half of that in response to glucose infusion.

Animals↗
PubMed1978

[Use of invert sugar, fructose and sorbitol and on their effect on various plasma constituents after intravenous infusion in the dog].

Glucose and fructose half-lives following intravenous infusion of 1.0 or 0.5 g/body weight invertose solution (200 g/l) were established in six Beagle dogs. The average half-lives measured were 7.8 for glucose (variation between 6.0 and 13.5) and 7.5 for fructose (variation between 4.5 and 11.0), all values given in minutes. Administration of invertose instead of glucose for parenteral energy supply proved favourable in various respects. Infusion of invertose was temporarily followed by rises within physiological limits of lactate and pyruvate in the blood and of insulin concentrations in the blood plasma, whereas the levels of free fatty acids declined. A 25-per-cent fructose solution was infused (0.5 g/kg body weight) to three dogs, and the half-lives then measured were six, nine, and 13 minutes. The insulin concentration rose temporarily, while the free fatty acids went down. The same doses of sorbite gave half-lives of 15.5 or 17 minutes. Infusion was followed by temporary increase of fructose and insulin in the blood plasma.

Animals↗
PubMed1977

Species-specific aggregation factor in sponges. Sialyltransferase associated with aggregation factor.

The sialyltransferase (= glycoprotein-sialic acid transferase) was studied in the sponge Geodia cydonium, a mesozoan organism. The experiments were performed both in intact cellular and in isolated enzyme systems. It is shown, that desialylated cells show a lower aggregation potency than the controls. During aggregation enzymic sialylation of desialylated sponge cells occurs in the presence of an aggregation factor, which is associated with a high molecular weight particle. The sialylation process is temperature-dependent and can be inhibited by N-ethylmaleimide. Sialylation occurs predominantly at a distinct cell surface component, the aggregation receptor. The sialyltransferase was isolated and purified by the following steps: Sepharose 4B, CM-cellulose, Nonidet treatment, and Sephadex G-100. By this procedure the enzyme was purified 680-fold with a 31% yield. The sialyltransferase is originally associated with the high molecular weight particle also carrying the aggregation factor. In the last step the aggregation factor was separated from the sialyltransferase. The enzyme catalyzes the transfer of sialic acid from CMP-sialic acid to the desialylated aggregation receptor. The molecular weight of the sialyltransferase has been determined to be 52,000. Kinetic studies revealed no lag phase and a dependence on enzyme concentration. The purified transferase has a pH optimum of 7.75 and requires 200 mM NaCl for activity. No requirement for Mg2+ or Ca2+ could be observed. The reaction is inhibited by 10 micronM N-ethylmaleimide.

Animals↗
PubMed1977

The presence of Herpesvirus Saimiri genomes in virus-transformed cells.

Herpesvirus saimiri (H. salmiri) -transformed cells contained both types of viral DNA, unique L-DNA and highly repetetive H-DNA. DNA from spleen and lymph-node autopsies of two tumor-bearing marmoset monkeys contained 0.14-0.75% viral L-DNA -AND 0.115-1.08% H-DNA. This amount of H-DNA would be equivalent to the presence of 14-130 M-genomes per diploid tumor tissue cell. Six virus-transformed lymphoid cell lines, two of them virus-producing, contained 0.69-2.27% H-DNA and more than 0.72-1.95% L-DNA. These concentrations of H-DNA sequences correspond to 83-274 M-genome copies per lymphoid tissue culture cell. The majority of viral genomes in transformed non-producer lymphoid cell lines appeared to be defective, since part of the L-sequences present in virions were found to be deleted in the genome copies of transformed cells. There was a relative excess of repetitive H-sequences in all transformed cells in regard to the ratio of H-DNA/L-DNA in M-genomes of H. saimiri virions.

Animals↗
PubMed1977

Consequences of detergent pollution of the sea: effects on regenerating sponge cubes of Geodia cydonium.

Regenerating cubes of the sponge Geodia cydonium cyconium were used as a model in the investigation of detergent pollution in the sea. The anionic detergent sodium dodecylsulphate (SDS) and a 1:1 mixture of Faks and Radion, two commercial laundry detergents, were used in the concentration range from 1 X 10(-9) g/ml (1 ppb) to 1 X 10(-5) g/ml. It is shown that SDS is taken up, weakly accumulated but not incorporated into the macromolecular fractions of the sponge. At concentrations of 0.1 ppm and above, SDS decreases the uptake of thymidine, uridine and phenylalanine into the acid-soluble sponge fraction. Their incorporation into the acid insoluble fractions, which have been isolated, was different from the controls at 10 ppb and higher levels. Faks and Radion were less active by a factor of 10. However, they showed similar effects. The chemical composition of the regenerating sponge cubes with respect to DNA, RNA and protein content has been evaluated. The alterations are less pronounced on detergent incubation than precursor uptake. The use of the cetyltrimethyl-ammoniumbromide-turbidity-dilution technique reveals drastic qualitative changes in the nucleic acid fractions. The relevant literature on biological effects of detergent is listed. It is shown that this investigation extends the scale of known effects far into the low and pollution-relevant concentration levels.

Animals↗