Secalonic acid D blocks embryonic palatal mesenchymal cell-cycle by altering the activity of CDK2 and the expression of p21 and cyclin E

BACKGROUND: The mycotoxin, secalonic acid D (SAD), a known animal and potential human cleft palate (CP)-inducing agent, is produced by Pencillium oxalicum in corn. SAD selectively inhibits proliferation of murine embryonic palatal mesenchymal (MEPM) cells leading to a reduction in cell numbers. These effects can explain the reduction in shelf size and the resulting CP seen in the offspring of SAD-exposed mice. Ability of SAD to inhibit proliferation as well as to block the progression of cells from G1- to S-phase of the cell-cycle were also shown in the human embryonic palatal mesenchymal (HEPM) cells suggesting the potential CP-inducing effect of SAD in human beings METHODS: Gestation day (GD) 12 mouse embryos and HEPM cells were used to test the hypothesis that the cell-cycle block induced by SAD results from a disruption of stage-specific regulatory components both in vivo and in vitro. The effects of SAD on the activity of various cyclin dependent kinases (CDK) and on the levels of various positive (cyclins and CDK) and negative (CDK inhibitors p15, 16, 18, 19, 21, 27, 57) cell-cycle regulators were assessed by performing kinase assays and immunoblots, respectively. RESULTS: In the murine embryonic palates, SAD specifically inhibited G1/S-phase-specific CDK2 activity, reduced the level of cyclin E and tended to increase the level of the CIP/kip CDK inhibitor, p21. In the HEPM cell cultures, exposure to IC50 of SAD significantly affected all of the above targets. In addition, a reduction in the levels/activity of CDK 4/6, a reduction in the levels of cyclins D1, D2, D3, E, A, and all INK4 family proteins, and an increase in the level of the CIP/kip CDK inhibitor, p57, were also seen. CONCLUSIONS: These results suggest that the S-phase-specific cell-cycle proteins CDK2, cyclin E and possibly p21 are the common targets of SAD in murine palatal shelves in vivo and in human embryonic palatal mesenchymal cells in vitro and may be relevant to the pathogenesis of SAD-induced CP.     

Guanylyl cyclase stimulatory coupling to K(Ca) channels

We coexpressed the human large-conductance, calcium-activated K(K_Ca) channel (- and -subunits) and rat atrialnatriuretic peptide (ANP) receptor genes in Xenopus oocytesto examine the mechanism of guanylyl cyclase stimulatory coupling tothe channel. Exposure of oocytes to ANP stimulated whole cellK_Ca currents by 21 ± 3% (at 60 mV), without alteringcurrent kinetics. Similarly, spermine NONOate, a nitric oxide donor,increased K_Ca currents (20 ± 4% at 60 mV) in oocytesexpressing the channel subunits alone. Stimulation of K_Cacurrents by ANP was inhibited in a concentration-dependent manner by apeptide inhibitor of cGMP-dependent protein kinase (PKG).Receptor/channel stimulatory coupling was not completely abolished bymutating the cAMP-dependent protein kinase phosphorylation site on the-subunit (S869; Nars M, Dhulipals PD, Wang YX, and Kotlikoff MI.J Biol Chem 273: 14920-14924, 1998) or by mutating a neighboring consensus PKG site (S855), but mutation of both residuesvirtually abolished coupling. Spermine NONOate also failed to stimulatechannels expressed from the double mutant cRNAs. These data indicatethat nitric oxide donors stimulate K_Ca channels throughcGMP-dependent phosphorylation and that two serine residues (855 and869) underlie this stimulatory coupling.

     

Beckwith-Wiedemann-Syndrom

The Beckwith-Wiedemann syndrome (BWS) is a pediatric overgrowth syndrome with a variable clinical appearance. The phenotype normalizes with age but the diagnosis of BWS is important as syndrome-specific complications may develop, in particular as a result of a 400-fold increased risk of patients developing certain tumor entities, predominantly nephroblastomas (Wilms’ tumors) and hepatoblastomas, within the first years of life. BWS displays a clinical overlap with other syndromes so that an unambiguous molecular diagnostic is required for risk assessment and appropriate therapy. At the molecular level BWS is associated with the chromosomal region 11p15.5, where two clusters with imprinted genes are located. In patients both genetic mutations and in most cases aberrant DNA methylation can be observed, which pathogenically affect the gene dosage of functionally available monoallelically expressed 11p15.5 genes. Currently only a very incomplete genotype-phenotype correlation exists for BWS. Current research projects provide insights in the molecular etiopathogenesis of the syndrome by identifying interacting partners which modify the epigenetic regulation of imprinted 11p15.5-genes.     

BioTRIZ Suggests Radiative Cooling of Buildings Can Be Done Passively by Changing the Structure of Roof Insulation to Let Longwave Infrared Pass

This paper demonstrates the application of a design tool called BioTRIZ. Its developers claim that it can be used to access biological strategies for solving engineering problems. Our aim is to design a roof for hot climates that gets free cooling through radiant coupling with the sky. The insulation in a standard roof stops the sun and convection from warming the thermal mass. But it also restricts the mass＇s longwave view of the cool sky. Different solutions to this conflict are offered by BioTRIZ. The chosen solution is to replace the standard insulation component with an open cell honeycomb. The vertical cells would allow longwave radiation to pass, while arresting convection. The solutions offered by BioTRIZ＇s technological counterpart include no such changes in structure. It is estimated that the thermal mass in the biomimetic roof would remain on average 4.5℃ cooler than in a standard roof over a year in Riyadh, Saudi Arabia.     

The innervation of the uterus in Salamandra salamandra (L.) (Amphibia,Urodela)

The innervation of the uterus in the ovoviviparous urodele Salamandra salamandra was studied. In whole mount preparations of the thin-walled uterus of pregnant females, a dense adrenergic network was demonstrated using a modified glyoxylic acid fluorescence technique. Based on vesicle type and cytochemical reactivity after chromate/dichromate fixation for electron microscopy at least two types of neural process were distinguished and classified as adrenergic and cholinergic. Both types are preferentially situated above or between the smooth muscles of the uterine tissue. Adjacent to the muscles in the walls of arterioles mainly adrenergic fibers are seen. Using high performance liquid chromatography with electrochemical detection in tissue homogenates of uterus a considerable amount of noradrenaline could be identified. The significance of the dense innervation is discussed with respect to the function of the uterus during pregnancy and birth.     

Therapie mitochondrialer Erkrankungen

Although there have been major advances in understanding the pathogenesis of mitochondrial disorders, current treatment is largely supportive and there is still no cure. A variety of pharmacological agents, vitamins and cofactors, dietary modifications and interventions are under investigation, including attempts to bypass blocks in the respiratory chain, antioxidative effects, supplementation of deficiencies of specific compounds or the removal of noxious metabolites. There is currently no clear evidence supporting the use of any of these interventions. However, replacement of deficient metabolites or elimination of toxic molecules might be beneficial in specific disorders. Moreover, current data suggest that idebenone might be useful in Leber??s hereditary optic neuropathy (LHON). Only few randomized controlled trials had been conducted to date, and future controlled trials are strongly needed to establish the role of therapeutic approaches in homogeneous study populations. Gene therapy is a challenge, but promising experimental approaches are being pursued.     

Gonosomale Mosaike

With an incidence of approximately 0.2?% in newborns gonosomal chromosome aberrations are of major relevance for clinical genetics. They frequently occur as numerical and/or structural gonosomal mosaicism. The correlation between genotype and phenotype is poor most probably due to different levels of mosaicism in different tissues and they represent a great challenge especially in prenatal diagnostics, requiring genetic counseling by an experienced clinical geneticist. Postnatally, gonosomal mosaicism in females often leads to the clinical symptoms of Turner’s syndrome (especially short stature and infertility) with an potentially increased risk for gonadoblastoma if an XY cell line is present. In males with Klinefelter’s syndrome mosaicism is also frequent (up to 20?%). Mosaicism in 47,XYY and 47,XXX karyotypes is rarely reported perhaps due to the innocuous phenotype seldom being an indication for chromosome analysis.