Kinetic studies on the diaqua form of cis-platin and various nucleobases

Kinetic studies on cis-[Pt(NH3)2(OH2)2]2+ and various nucleobases show that this ion reacts more quickly with guanosine than with adenosine, cytidine, and thymidine, and that a monophosphoric acid unit considerably enhances the rate of reaction of guanosine; the kinetic preference of 5'-GMP over 5'-AMP may point to a greater thermodynamic selectivity.     

Computer simulation of cellular movements: cell-sorting, cellular migration through a mass of cells and contact inhibition

The motility rules for cellular movement proposed earlier by Goel &; Rogers for engulfment of two or more intact embryonic tissues have been used to simulate on a computer the phenomena of cell-sorting, migration of individual cells through a mass of cells and contact inhibition of overlapping. These simulations in the most part are found to be consistent with the observations with real cells.     

Simple derivation of the function of genetic information and correction of the proof

The problem of predicting time to extinction in stochastics population models is approached in two ways. First, a finite Markov chain approximation is used to give the distribution of time to extinction and shown to predict simulation results accurately. Second, an approximate numerical integration technique is found to give good relative predictions of persistence using much less computer time. The relevance of the two approaches to real problems is discussed.     

Editorial: Twin peaks mission

The Y human chromosome has many ancient genes whose fidelity seems to have been preserved by tandem sequences and palindromic ‘hairpins’, compared/repaired by ‘gene conversion’. That a primary function of recombination machinery is DNA repair has been suggested, and rejected, several times; this new evidence is very persuasive. The process, better called gene conservation than gene conversion, could operate in all diploid organisms, accounting for the retention of long gene sequences without ‘informational meltdown’ ('concerted evolution'). It resembles rocket‐science computer‐redundancy error‐checking, comparison of three or four sequences, not just two. If recognition of errors in ‘converted’ sequences can be followed by either repair or rejection, the rejection option can account for the vast wastage of meiotic products. The repair option might be used in Drosophila oocytes and even zygotic nuclei, possibly other oocytes, ancient asexual lineages such as mycorrhizal fungi, perhaps the Y itself. Both evolutionary stasis (conservatism) and development and deployment of complex developmental modules can be understood in these terms so both the evolution of biodiversity and the practice of systematics may have these mechanisms as their bases. The main individual‐fitness and evolutionary advantages of diploidy were not primarily cloaking of recessive al‐leles, or allelic recombination and Mendelism, but conserving long DNA sequences.     

Neuroprotective potentials of neurotrophin rich olfactory ensheathing cell's conditioned media against 6OHDA-induced oxidative damage

Abstract

On the basis of recent reports, we propose that impaired neurotrophin signaling (PI3k/Akt), low antioxidant levels, and generation of reactive oxygen species (ROS) conjointly participate in the progressive events responsible for the dopaminergic cell loss in Parkinson's disease (PD). In the present study we tried to target these deficits collectively through multiple neurotrophic factors (NTFs) support in the form of Olfactory Ensheathing Cell's Conditioned Media (OEC CM) using human SH-SY5Y neuroblastoma cell line exposed to 6 hydroxydopamine (6OHDA). 6OHDA exposure induced, oxidative stress-mediated apoptotic cell death viz. enhanced ROS generation, diffused cytosolic cytochrome c (cyt c), impaired Bcl-2: Bax levels along with decrease in GSH content. These changes were accompanied by loss in Akt phosphorylation and TH levels in SH-SY5Y cells. OEC CM significantly checked apoptotic cell death by preserving pAkt levels which coincided with enhanced GSH and suppressed oxidative injury. Functional integrity of OEC CM supported cells was evident by maintained tyrosine hydroxylase (TH) expression. Intercepting Akt signaling by specific inhibitor LY294002 blocked the protective effect. Taken together our findings provide important evidence that the key to protective effect of multiple NTF support via OEC CM is enhanced Akt survival signaling which promotes antioxidant defense leading to suppression of oxidative damage.     

Nicotinic Receptor-Mediated Release of Noradrenaline in the Human Neuroblastoma SH-SY5Y

Abstract: Dimethylphenylpiperazinium iodide (a nicotinic agonist) evokes noradrenaline release from human neuroblastoma SH-SY5Y cells that have been pretreated with 12- O -tetradecanoylphorbol 13-acetate for 8 min. This effect of dimethylphenylpiperazinium iodide was inhibited by 1 μ M mecamylamine but not by 1 μ M atropine, which suggests that SH-SY5Y cells express nicotinic receptors coupled to the release of noradrenaline. Dimethylphenylpiperazinium iodide-evoked release was enhanced by 5 μ M Bay K 8644 (an L-type calcium agonist) and inhibited by 1 μ M nifedipine. Dimethylphenylpiperazinium iodide depolarised SH-SY5Y cells and enhanced the level of intracellular calcium in cells loaded with fura 2. The effects of dimethylphenylpiperazinium iodide on noradrenaline release, depolarisation, and intracellular calcium levels were all inhibited by 1 μ M desmethylimipramine. The results of this study show that nicotinic receptors in SH-SY5Y cells stimulate noradrenaline release by activation of L-type calcium channels.     

Photoluminescence and piezoelectric behaviour of Y2Zr2O7 pyrochlore‐based multifunctional materials and the influence of Eu3+ and Sm3+

Y₂Zr₂O₇‐doped with Eu³⁺ and Sm³⁺ phosphors were prepared for the first time as multifunctional smart materials using a solid‐state reaction method at 1400^oC. Thermal behaviour, crystal structure, surface morphology, and elemental analysis were characterized using thermogravimetric (TG) and differential thermal (DTA) analyses, X‐ray diffraction (XRD) and scanning electron microscope equipped with energy‐dispersive X‐ray spectroscopy (SEM‐EDX). Experimental results revealed that both phosphors have a pyrochlore structure with a cubic crystal system. Photoluminescence properties were also measured and red emission was observed from Y_1.90Eu_0.10Zr₂O₇ and Y_1.90Sm_0.10Zr₂O₇ phosphors. Dielectric constant, loss tangent, piezoelectric charge constant, and Curie temperature of all the samples were determined using an LCR‐meter, d₃₃‐meter, and TG/DTA. Eu doping in Y₂Zr₂O₇ resulted in a high dielectric constant (9.61) and low loss tangent (1.67%) values, whereas high piezoelectric charge constant (0.68 pC/N) and high Curie temperature (820°C) could be obtained using Sm‐doped Y₂Zr₂O₇.     

Molten salt synthesis and luminescence of Dy3+‐doped Y3Al5O12 phosphors

Dy³⁺‐doped Y₃Al₅O₁₂ phosphors were prepared at a relatively low temperature using molten salt synthesis. The phase of the prepared Dy³⁺‐doped Y₃Al₅O₁₂ phosphors was confirmed using X‐ray powder diffraction. Results indicated that Dy³⁺ doping did not change the Y₃Al₅O₁₂ phase. Following excitation at 352 nm, emission spectra of the Dy³⁺‐doped Y₃Al₅O₁₂ phosphors consisted of blue, yellow, and red emission bands. The influence of Dy³⁺ concentration and excitation wavelength on emission was investigated. The ratio of yellow light to blue light varied with change in Dy³⁺ doping concentration, due to changes in the structure around Dy³⁺. Emission intensities also changed when the excitation wavelength was changed. This variation is luminescence generated a system for tunable white light for Dy³⁺‐doped Y₃Al₅O₁₂ phosphors.     

A ROCK inhibitor promotes keratinocyte survival and paracrine secretion,enhancing establishment of primary human melanocytes and melanocyte–keratinocyte co‐cultures

Primary melanocytes isolated from skin and expanded in culture have been widely used for laboratory research and clinical applications. The conventional method to isolate primary melanocytes from skin usually requires about 3–4 weeks of culture for melanocytes to grow sufficiently to passage. Considering that melanocytes comprise only 3%–7% of epidermal cells in normal human skin, it would be extremely helpful to increase the isolation efficiency and shorten the initial culture time to quickly meet various application needs. Here, we report that adding Y‐27632, a Rho kinase inhibitor, into the initial culture medium for 2 days can dramatically increase the yield of melanocytes. We found that Y‐27632 can promote keratinocyte attachment and survival in the melanocyte culture system, resulting in not only better recovery, but also increased proliferation of melanocytes by a paracrine signaling pathway. More specifically, Y‐27632 significantly induced keratinocyte expression of stem cell factor, which played an important role in enhancing the growth of melanocytes. In summary, Y‐27632 could profoundly enhance the yield of primary melanocytes in the initial culture through paracrine effects on keratinocytes.