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.     

Two applications of the divide&conquer principle in the molecular sciences

In this paper, two problems from the molecular sciences are addressed: the enumeration of fullerene-type isomers and the alignment of biosequences. We report on two algorithms dealing with these problems both of which are based on the well-known and widely used Divide&Conquer principle. In other words, our algorithms attack the original problems by associating with them an appropriate number of much simpler problems whose solutions can be “glued together” to yield solutions of the original, rather complex tasks. The considerable improvements achieved this way exemplify that the present day molecular sciences offer many worthwhile opportunities for the effective use of fundamental algorithmic principles and architectures.     

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).     

Layered double hydroxide-CdSe quantum dot composites through colloidal processing: effect of host matrix-nanoparticle interaction on optical behavior

Layered double hydroxide (LDH)-monodispersed 4-nm CdSe nanoparticle composites were prepared through restacking of layers of colloidally dispersed delaminated LDH in the presence of CdSe nanoparticles in 1-butanol. The composites exhibit a blue shift for CdSe absorption, which increases with a decrease in nanoparticle content. The observed blue shift is due to the interaction of the quantum dots with the LDH layers, which leads to surface modification of the nanoparticles.     

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.     

Reverse plasticity in single crystal silicon nanospheres

Nanoparticles in the range of 20 to 100 nm in size can be deposited, isolated, and individually probed for their mechanical properties. With a hypersonic plasma particle deposition technique, this has been successfully accomplished for silicon and titanium. We have already shown that silicon nanoparticles are superhard in the 30 to 50 GPa range after work hardening (Gerberich, W.W., Mook, W.M., Perrey, C.R., Carter, C.B., Baskes, M.I., Mukherjee, R., Gidwani, A., Heberlein, J., McMurry, P.H., Girshick, S.L., 2003a. Superhard silicon nanospheres. J. Mech. Phys. Solids 51, 979). At the same time when small nanospheres are compressed, a fraction of the plastic strain is reversed after unloading. Initially, the amount of reverse dislocation motion was small but appeared to accelerate once a threshold strain was reached. The cumulative reverse plastic strain from repeated loading of the same nanosphere appeared to increase from less than 0.04 to approximately 0.4 as cumulative strain increased from 0.2 to 0.6. For large strains then, it appears that a greater amount of plastic strain is recovered after unloading. This can at least partially be understood in terms of the enormous back stress developed at the small scale when dislocations are only a few nm apart. As the ramifications to nanoscopic features on MEMS, micromachines and magnetic recording devices is considerable, it is desirable to understand if a length scale can be developed for such phenomena. In terms of classic dislocation theory an attempt is made. Problems and prospects are discussed with regards to predictive models for hardness and reverse plasticity.     

Study of radiation damage induced by 12 keV X‐rays in MOS structures built on high‐resistivity n‐type silicon

Imaging experiments at the European X‐ray Free Electron Laser (XFEL) require silicon pixel sensors with extraordinary performance specifications: doses of up to 1 GGy of 12 keV photons, up to 10⁵ 12 keV photons per 200 µm × 200 µm pixel arriving within less than 100 fs, and a time interval between XFEL pulses of 220 ns. To address these challenges, in particular the question of radiation damage, the properties of the SiO₂ layer and of the Si–SiO₂ interface, using MOS (metal‐oxide‐semiconductor) capacitors manufactured on high‐resistivity n‐type silicon irradiated to X‐ray doses between 10 kGy and 1 GGy, have been studied. Measurements of capacitance/conductance–voltage (C/G–V) at different frequencies, as well as of thermal dielectric relaxation current (TDRC), have been performed. The data can be described by a dose‐dependent oxide charge density and three dominant radiation‐induced interface states with Gaussian‐like energy distributions in the silicon band gap. It is found that the densities of the fixed oxide charges and of the three interface states increase up to dose values of approximately 10 MGy and then saturate or even decrease. The shapes and the frequency dependences of the C/G–V measurements can be quantitatively described by a simple model using the parameters extracted from the TDRC measurements.