TSH compensates thyroid-specific IGF-I receptor knockout and causes papillary thyroid hyperplasia

Although TSH stimulates all aspects of thyroid physiology IGF-I signaling through a tyrosine kinase-containing transmembrane receptor exhibits a permissive impact on TSH action. To better understand the importance of the IGF-I receptor in the thyroid in vivo, we inactivated the Igf1r with a Tg promoter-driven Cre-lox system in mice. We studied male and female mice with thyroidal wild-type, Igf1r(+/-), and Igf1r(-/-) genotypes. Targeted Igf1r inactivation did transiently reduce thyroid hormone levels and significantly increased TSH levels in both heterozygous and homozygous mice without affecting thyroid weight. Histological analysis of thyroid tissue with Igf1r inactivation revealed hyperplasia and heterogeneous follicle structure. From 4 months of age, we detected papillary thyroid architecture in heterozygous and homozygous mice. We also noted increased body weight of male mice with a homozygous thyroidal null mutation in the Igf1r locus, compared with wild-type mice, respectively. A decrease of mRNA and protein for thyroid peroxidase and increased mRNA and protein for IGF-II receptor but no significant mRNA changes for the insulin receptor, the TSH receptor, and the sodium-iodide-symporter in both Igf1r(+/-) and Igf1r(-/-) mice were detected. Our results suggest that the strong increase of TSH benefits papillary thyroid hyperplasia and completely compensates the loss of IGF-I receptor signaling at the level of thyroid hormones without significant increase in thyroid weight. This could indicate that the IGF-I receptor signaling is less essential for thyroid hormone synthesis but maintains homeostasis and normal thyroid morphogenesis.     

Poly(ethylenimine-co-L-lactamide-co-succinamide): a biodegradable polyethylenimine derivative with an advantageous pH-dependent hydrolytic degradation for gene delivery

A biodegradable gene transfer vector has been synthesized by linking several low molecular weight (MW) polyethylenimine (PEI, 1200 Da) blocks using an oligo(L-lactic acid-co-succinic acid) (OLSA, 1000 Da). The resulting copolymer P(EI-co-LSA) (8 kDa) is soluble in water and degrades via base-catalyzed hydrolytic cleavage of amide bonds. With regard to its application as a gene transfer agent, the polymer showed an interesting pH dependency of degradation. At pH 5, when DNases are highly active, the degradation proceeds at a slower rate than at a physiological pH of 7.4. PEI and P(EI-co-LSA) spontaneously formed complexes with plasmid DNA. Whereas the complexes formed with PEI were not stable and aggregated, forming particles of up to 1 microm hydrodynamic diameter, P(EI-co-LSA) formed complexes, which were about 150 nm in size and of narrow size distribution. The latter complexes were stable, due to their high surface charge (zeta-potential + 18 mV). Similar to low MW PEI, the copolymer exhibited a low toxicity profile. At the same time, the copolymer showed a significant enhancement of transfection activity in comparison to the low MW PEI. This makes P(EI-co-LSA) a promising candidate for long-term gene therapy where biocompatibility and biodegradability become increasingly important.     

Characterization of SVEP1, KIAA, and SRPX2 in an in vitro cell culture model of endotoxemia

To assess the influence of unknown factors in endotoxemia, a conditioned medium, achieved by the stimulation of THP1 monocytes with lipopolysaccharide (LPS) [4 h], was used for the stimulation of human umbilical vein endothelial cells (HUVECs) [16 h]. SVEP1, KIAA0247, and SRPX2 were selected after microarray analysis. To study their possible functions, siRNAs of SVEP1, KIAA0247, or SRPX2 were used for the transfection of HUVECs and cells were stimulated with conditioned medium [16 h]. Inhibition of SVEP1 expression resulted in an increase of soluble intercellular adhesion molecule (sICAM) 1 (10%) and soluble E-selectin (sE-selectin) (19%). Inhibition of SRPX2 led to an increase of sICAM (11%) and sE-selectin (14%). KIAA0247 negative HUVECs showed a decrease in monocyte chemoattractant protein (MCP) 1 of 16%. SVEP1 and SRPX2 seemed to act as regulators of ICAM1 and E-selectin shedding and influence the expression of membrane bound adhesion molecules.     

Inter- und intrachromosomale Verteilung von Chromatidtranslokationen nach Einwirkung von Trenimon auf menschliche Leukocyten in vitro

Zusammenfassung 250 Trenimon-induzierte Chromatidtranslokationen wurden bezüglich ihrer Konfiguration, der Beteiligung der einzelnen Chromosomen bzw. Chromosomengruppen und der Lage der Austauschstellen analysiert. Cis- und trans-Konfiguration (= asymmetrische und symmetrische Translokation) traten in etwa der gleichen Häufigkeit auf, ebenso vollständige und unvollständige Reunion der Bruchflächen. Sowohl die inter- als auch die intrachromosomale Verteilung der Austauschstellen war nicht zufallsgemäß. Homologe Chromosomen waren häufiger an Austauschfiguren beteiligt als nach den relativen Längenanteilen zu erwarten war. Die Chromosomen 6-12+X, 16 und 21+22 nahmen häufiger, die Chromosomen 2–5 seltener am Austausch teil, als erwartet. Die Austauschstellen waren sehr häufig in den proximalen Chromosomenabschnitten (incl. Centromer) sowie in den kurzen Armen der Chromosomen 13–15 und 21+22 lokalisiert.

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Inter- and intrachromosomal distribution of chromatid translocations in human leukocytes after in vitro treatment with trenimon

250 chromatid interchanges induced by Trenimon were analyzed relative to their configuration, the participation of certain chromosomes or chromosome groups and the localization of the exchange points. Cis- and trans-configuration (=asymmetrical and symmetrical interchanges) have been observed in identical frequency. The same was seen relative to complete and incomplete reunion of the breaks. The interchromosomal as well as the intrachromosomal distribution of the exchange points was non-random. Homologous chromosomes participated in interchanges at a higher level of frequency than expected from their relative length. Chromosomes No. 6–12 and X as well as 16 and 21+22 took part in interchanges more frequently and chromosomes No. 2, 3, 4 and 5 more rarely than expected. The exchange points were frequently observed in the proximal regions of the chromosomes (incl. centromere) as well as in the short arms of chromosomes No. 13–15 and 21+22.

     

Role for glycine betaine transport in Vibrio cholerae osmoadaptation and biofilm formation within microbial communities

Vibrio cholerae is a halophilic facultative human pathogen found in marine and estuarine environments. Accumulation of compatible solutes is important for growth of V. cholerae at NaCl concentrations greater than 250 mM. We have identified and characterized two compatible solute transporters, OpuD and PutP, that are involved in uptake of glycine betaine and proline by V. cholerae. V. cholerae does not, however, possess the bet genes, suggesting that it is unable to synthesize glycine betaine. In contrast, many Vibrio species are able to synthesize glycine betaine from choline. It has been shown that many bacteria not only synthesize but also secrete glycine betaine. We hypothesized that sharing of compatible solutes might be a mechanism for cooperativity in microbial communities. In fact, we have demonstrated that, in high-osmolarity medium, V. cholerae growth and biofilm development are enhanced by supplementation with either glycine betaine or spent media from other bacterial species. Thus, we propose that compatible solutes provided by other microorganisms may contribute to survival of V. cholerae in the marine environment through facilitation of osmoadaptation and biofilm development.     

Co-existence of immunoreactivity to anti-dopamine,anti-serotonin and anti-vasotocin in the cerebral giant neuron of the pond snail Lymnaea stagnalis

Summary Consecutive sections of certain neurons in the central ganglia of the pond snail Lymnaea stagnalis appear to be immunoreactive to anti-dopamine and anti-serotonin. The Cerebral Giant Neurons stain in addition with antivasotocin. The observations indicate the presence of two biogenic amines within the same neuron and in addition their co-existence with a biologically active peptide.     

Phosphorylation by liver glucokinase of D-glucose anomers at anomeric equilibrium

The relative contribution of each anomer of D-glucose to the overall phosphorylation rate of the hexose tested at anomeric equilibrium was examined in rat liver postmicrosomal supernatants under conditions aimed at characterizing the activity of glucokinase, with negligible interference of either hexokinase, N-acetyl-D-glucosamine kinase or glucose-6-phosphatase (acting as a phosphotransferase). Both at 10 degrees and 30 degrees C, the relative contribution of each anomer was unaffected by the concentration of D-glucose. At both temperatures, the alpha/beta ratio for the contribution of each anomer was slightly, but significantly, lower than the alpha/beta ratio of anomer concentrations. These findings, which are consistent with the anomeric specificity of glucokinase in terms of affinity, cooperativity and maximal velocity, reveal that the preferred alpha-anomeric substrate for both glycogen synthesis and glycolysis is generated by glucokinase at a lower rate than is beta-D-glucose-6-phosphate.     

Subcellular compartmentation of pyrophosphate and dark/light kinetics in comparison to fructose 2,6-bisphosphate

Subcellular compartmentation of pyrophosphate (PP₁) was determined by rapid membrane filtration of evaeuolated oat mesophyll protoplasts. By improving both the extraction procedure and its assay via bioluminescence, PP₁ recovery from samples was quantitative and linear down to below 200 fmol. Based on the content of the different fractions obtained after membrane filtration and compared to the respective pools of marker metabolites [cytosol, fructose 2,6-bisphosphate (F26BP); chloroplast stroma, ribulose bisphosphate] rather than enzymes, we found ca 2/3 of the total cellular content to be chloroplast-assotiated. Referred to compartmental volumes, cytosolic and stromal concentrations of PP₁ were nearly equal (70–100 μ M ). PP₁ was higher in evacuolated compared to racuotated protoplasts which indicates a possible role of the tonoplast-located H⁺ pumping PP₁ase in regulating the cellular pool size of PP₁. During dark-light-transition the pool sizes of PP₁ changed only marginally in both vacuolated and evacuolated protoplasts, while there were pronounced changes in those of F26BP, starch and sucrose. Thus our findings support the notion that the cellular pool size of PP₁ is kept rather constant. They are, however, in contrast to the assumption that appreciable PP₁ levels only exist in the cytosol.