Differential inhibition of postnatal brain,spinal cord and body growth by a growth hormone antagonist

Background  

Growth hormone (GH) plays an incompletely understood role in the development of the central nervous system (CNS). In this study, we use transgenic mice expressing a growth hormone antagonist (GHA) to explore the role of GH in regulating postnatal brain, spinal cord and body growth into adulthood. The GHA transgene encodes a protein that inhibits the binding of GH to its receptor, specifically antagonizing the trophic effects of endogenous GH.     

Fusion around the barrier for 7Li+12C

Fusion cross-sections for the ⁷Li + ¹²C reaction have been measured at energies above the Coulomb barrier by the direct detection of evaporation residues. The heavy evaporation residues with energies below 3 MeV could not be separated out from the α-particles in the spectrum and hence their contribution was estimated using statistical model calculations. The present work indicates that suppression of fusion cross-sections due to the breakup of ⁷Li may not be significant for ⁷Li + ¹²C reaction at energies around the barrier.     

Synthesis,Structures, and Properties of Branched Oligogermanes

Abstract

We have employed the hydrogermolysis reaction for the preparation of rare branched oligogermanes, and have obtained for the first time the X-ray crystal structures of several branched tetragermanes, including (Ph₃Ge)₃GePh, (Ph₃Ge)₃GeH, and (Ph₃Ge)₃GeX (X = Cl or Br). We also have at our disposal branched tetragermanes having the formula (EtOCH₂CH₂Bu ⁿ ₂Ge)₃GePh, where the ethoxyethyl substituent serves as a protecting group for a germanium–hydride active site. These reagents have been employed for the stepwise synthesis of higher branched systems having up to 13 bonded germanium atoms in the oligomer backbone. The synthesis, structures, and physical characteristics of these systems are described.

GRAPHICAL ABSTRACT     

Convenient synthesis of aluminum and gallium phosphonate cages

The reactions of AlCl 3.6H 2O and GaCl 3 with 2-pyridylphosphonic acid (2PypoH 2) and 4-pyridylphosphonic acid (4PypoH 2) afford cyclic aluminum and gallium phosphonate structures of [(2PypoH) 4Al 4(OH 2) 12]Cl 8.6H 2O ( 1), [(4PypoH) 4Al 4(OH 2) 12]Cl 8.11H 2O ( 2), [(2PypoH) 4Al 4(OH 2) 12](NO 3) 8.7H 2O ( 3), [(2PypoH) 2(2Pypo) 4Ga 8Cl 12(OH 2) 4(thf) 2](GaCl 4) 2..8thf ( 4), and [(2PypoH) 2(2Pypo) 4Ga 8Cl 12(OH 2) 4(thf) 2](NO 3) 2.9thf ( 5). Structures 1- 3 feature four aluminum atoms bridged by oxygen atoms from the phosphonate moiety and show structural resemblance to the secondary building units found in zeolites and aluminum phosphates. The gallium complexes, 4 and 5, have eight gallium atoms bridged by phosphonate moieties with two GaCl 4 (-) counterions present in 4 and nitrate ions in 5. The cage structures 1- 3 are interlinked by strong hydrogen bonds, forming polymeric chains that, for aluminum, are thermally robust. Exchange of the phosphonic acid for the more flexible 4PyCH 2PO 3H 2 afforded a coordination polymer with a 1:1 Ga:P ratio, {[(4PyCH 2PO 3H)Ga(OH 2) 3](NO 3) 2.0.5H 2O} x ( 6). Complexes 1- 6 were characterized by single-crystal X-ray diffraction, NMR, and mass spectrometry and studied by TGA.     

Absorption,electrochemical, theoretical,and 73Ge NMR spectral characterization of the germanium neo-pentane analogue (Me3Ge)4Ge

The germanium-based neo-pentane analogue (Me₃Ge)₄Ge has been characterized by UV/visible spectroscopy, cyclic voltammetry, and ⁷³Ge NMR spectroscopy as well as by density functional theory (DFT) calculations. The absorption maximum for (Me₃Ge)₄Ge is blue-shifted relative to those for other related branched oligogermanes (Ph₃Ge)₃GeH and (Ph₃Ge)₃GePh, and this species is also the most difficult to oxidize among these three compounds. DFT calculations indicate the HOMO of (Me₃Ge)₄Ge is stabilized relative to those for both tetragermanes by ca. 0.5 eV and therefore the theoretical and experimental results are in agreement. The ⁷³Ge NMR spectrum of (Me₃Ge)₄Ge exhibits two resonances and the feature corresponding to the central formally zero-valent germanium atom is shifted far upfield and was observed at δ ?339 ppm.     

Detection of human and rodent 5-HT3B receptor subunits by anti-peptide polyclonal antibodies

Background  

The 5-HT₃ receptor is a member of a neurotransmitter-gated ion channel family which includes nicotinic acetylcholine, GABA_A, and glycine receptors. While antibodies specific for the 5-HT_3A receptor subunit are plentiful, and have revealed a wealth of structural and functional information, few antisera exist for the detection of 5-HT_3B receptor subunits. Here we describe the generation and characterisation of a rabbit polyclonal antiserum that specifically recognises 5-HT_3B receptor subunits     

Dibenzyl Structuresin a Macromolecular Chain. III. Dibenzyldiisocyanates Reactivity

The reactivity of the 2,2′-, 2,4′-, 4,4′-dibenzyldiisocyanate (2,2′-, 2,4′-, 4,4′-DBDI) with n-butanol in benzene has been studied. The concentrations of all species were monitored by using high performance liquid chromatography (HPLC). The reactivity of 4,4′-DBDI is similar to that of 4,4′-diphenylmethanediisocyanate (4,4′-MDI). Very strong intramolecular catalytic effects were noticed in the case of 2,2′-DBDI, probably due to the variable molecular geometry. These effects are responsible for the whole reaction pattern. The 2,4′-DBDI NCO ortho and para groups reactivities are different and comparable to that of 2,4-toluylenediisocyanate (2,4-TDI).     

Reactivity of α-germyl nitriles with acetonitrile: Synthesis, structures, and generation of Ph3Ge[NHC(CH3)CHCN] and 2,6-dimethyl-4-(triphenylgermylamino)pyrimidine from Ph3GeCH2CN

The formation of 3-aminocrotononitrile and 4-amino-2,6-dimethylaminopyrimidine has been observed during the course of the hydrogermolysis reaction between a germanium amide and a germanium hydride, either as the free amines or bound to germanium as ligands consisting of their conjugate bases. These species arise from the dimerization or trimerization of acetonitrile, and have only been detected when germanium amides having substantial steric bulk at the germanium center are employed in the reaction. The isolation of germanium-bound 3-aminocrotononitrile compounds suggests that α-germyl nitrile species R₃GeCH₂CN that result from the reaction of the germanium amides R₃GeNMe₂ with CH₃CN solvent also can further react with CH₃CN to generate the 3-aminocrotononitrile and 4-amido-2,6-dimethylaminopyrimidine species. The two germanes Ph₃Ge[NHC(CH₃)CHCN] and 2,6-dimethyl-4-(triphenylgermylamino)pyrimidine have been prepared and structurally characterized, and the conversion of Ph₃GeCH₂CN to Ph₃Ge[NHC(CH₃)CHCN] and 2,6-dimethylamino-4-(triphenylgermylamino)pyrimidine as well as the conversion of Ph₃Ge[NHC(CH₃)CHCN] to 2,6-dimethyl-4-(triphenylgermylamino)pyrimidine in acetonitrile solvent has been observed using ¹H NMR spectroscopy.     

The role of the t-SNARE SNAP-25 in action potential-dependent calcium signaling and expression in GABAergic and glutamatergic neurons

Background  

The soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complex, comprised of SNAP-25, syntaxin 1A, and VAMP-2, has been shown to be responsible for action potential (AP)-dependent, calcium-triggered release of several neurotransmitters. However, this basic fusogenic protein complex may be further specialized to suit the requirements for different neurotransmitter systems, as exemplified by neurons and neuroendocrine cells. In this study, we investigate the effects of SNAP-25 ablation on spontaneous neuronal activity and the expression of functionally distinct isoforms of this t-SNARE in GABAergic and glutamatergic neurons of the adult brain.