Diphenylhydantoin reduces calcium Ca 45 uptake and outflow in resting lobster axons and eliminates the increase in 45Ca accumulation that normally occurs during stimulation. Hydroxyphenyl-phenylhydantoin was found to be without effect on resting or stimulated nerves with respect to 45Ca uptake. Procaine hydrochloride shared the same effects as diphenylhydantoin on resting nerves. It is hypothesized that a major mechanism of action of diphenylhydantoin is similar to that of local anesthetics. (Arch Neurol 31:250-254, 1974) Bi ochemi cal experiments have in¬ dicated that diphenylhydantoin limits the increase of axonal sodium permeability that occurs during stim¬ ulation.1 These results are consistent with the finding that diphenylhydan¬ toin reduces the amplitude of action potentials in the giant axon of the squid2·3 and in the crayfish stretch re¬ ceptor.4 However, the major anticonvulsant effect of diphenylhydan¬ toin is attributed to its reversal of posttetanic potentiation.5 Posttetanic potentiation refers to the increase in the size of the postsynaptic compound action potential elicited by pre¬ synaptic stimulation following a re¬ petitive stimulus. The phenomenon of posttetanic potentiation is preceded by an intracellular accumulation of calcium in axon terminals, which oc¬ curs during the repetitive stimulus.6The accumulation of calcium in¬ creases transmitter release from the axon terminals during the posttetanic stimulus and therefore the size of the postsynaptic potential is greater af¬ ter the repetitive stimulus.The known effects of diphenylhy¬ dantoin are compatible with the hy¬ pothesis that diphenylhydantoin may interact competitively with calcium at the membrane.7·8 According to this hypothesis, diphenylhydantoin would limit the intracellular accumulation of calcium during stimulation and, thus, would inhibit stimulus-coupled, calcium-dependent processes like transmitter release. Calcium has a membrane "stabilizing" effect and is known to reduce axonal sodium con¬ ductance.9 If diphenylhydantoin occu¬ pied "calcium sites" on the nerve membrane, it might be an even more potent impediment to sodium move¬ ment than calcium. Hence, the effects of diphenylhydantoin on sodium con¬ ductance seen in the axons of inverte¬ brates might be the result of a pri¬ mary interaction with calcium. Thus, it seemed reasonable to investigate the relationship of diphenylhydantoin and calcium in lobster walking nerves. Walking nerves of the lobster were chosen because of their avail¬ ability, large size, the ease with which the extracellular space can be per¬ fused, and the substantial quantity of information about cationic move¬ ments in this preparation that has ac¬ cumulated from previous experiments in this laboratory, especially with re¬ spect to the effect of diphenylhydan¬ toin.1·10·11 MethodsWalking nerves were removed from lob¬ sters and tied on both ends. They were then laid on platinum electrodes and an ac¬ tion potential was evoked by stimulation. Nerves that failed to respond were dis¬ carded. The test was...

This study was conducted to develop a non-destructive detection method for adulterated powder products using Raman spectroscopy and partial least squares regression(PLSR). Garlic and ginger powder, which are used as natural seasoning and in health supplement foods, were selected for this experiment. Samples were adulterated with corn starch in concentrations of 5-35%. PLSR models for adulterated garlic and ginger powders were developed and their performances evaluated using cross validation. The    and  of an optimal PLSR model were 0.99 and 2.16 for the garlic powder samples, and 0.99 and 0.84 for the ginger samples, respectively. The variable importance in projection (VIP) score is a useful and simple tool for the evaluation of the importance of each variable in a PLSR model. After the VIP scores were taken pre-selection, the Raman spectrum data was reduced by one third. New PLSR models, based on a reduced number of wavelengths selected by the VIP scores technique, gave good predictions for the adulterated garlic and ginger powder samples.

Objectives:The aim of this study was to evaluate the optical characteristics such as color and translucency changes before and after light curing, to quantify the CQ and to measure refractive indices of body and opaque shade of resin composites materials. Materials and Methods: Resin composites used in this study were A2 body and A2 opaque shade of Esthet-X, Filtek supreme, Gradia Direct, Clearfil Majesty and BeautifilⅡ. Color and translucency changes before and after light curing were evaluated by colorimeter, the CQ was quantified by GC-MS and refractive index changes were measured by spectroscopic ellipsometer. Results: Translucency parameter (TP) was significantly increased after curing. The CQ content of body shades are higher than that of opaque shades in all resin composites. Refractive index increased after polymerization in all materials and significant difference in Δrefractive index was found between body and opaque shade (significance level 0.05). Conclusions: For an accurate shade match, direct shade matching of resin composite should be performed by using the cured material. [J Kor Acad Cons Dent 2011;36(3) properties such as color and translucency of the resin composites do not change before and after light curing, direct shade matching can be performed without light curing, resulting in spending less time. Therefore, stability in color and translucency before and after light curing would be an important property in esthetic restorative materials.Resin composite restorations may provide relatively poor color matches, specially a grayish shade is often seen after restoration, which is caused by a projection of the darkness in the oral cavity. From this point of view, the translucency of resin composites must be considered as a critical property just like the color of the material itself. 10,11 The translucency parameter (TP) is the color difference of a material having uniform thickness black and white backings, and corresponds directly to common visual assessments of translucency. 12The composite curing features are strongly influenced by the type and amount of photoinitiators inside.13 Camphorquinone (CQ) is the photosensitizing agent used in most of the brands available on the market. The increase in CQ amount in resin composites leads to a higher level of monomer conversion, improving mechanical and biological properties of these materials.14,15 Studies have shown that there is a limit for the increase of CQ concentration. 16,17 Above this limit the increase in photoinitiator does not benefit the final grade conversion. CQ has the aspect of an intense-yellow-colored powder. Additionally, it has poor photobleaching, which means the yellow color remains the same after light irradiation. Thus, CQ addition turns the material yellowish, making it difficult to be incorporated when lighter shades are desired. 16,18 Most of the organic molecules present in the matrix phase of dental composites and fillers do not effectively transmit visible light. As a result, scattering of light might be considered as...

The rate of fetus with abnormal chromosomes increase with maternal age. Nondisjunction of aging oocyte chromosome is a major reason for the increased rate of abnormalities. Telomeres are the ends of eukaryotic chromosome, which are essential for chromosome stability and are related in cell senescence. This study was carried out to analyze the chromosome aberration rate and amount of telomeric DNA in chick embryo along with maternal age. Fertilized eggs and blood were sampled from White Leghorn layers starting at 20 weeks through to 70 weeks age at 10 weeks interval. Chromosome aberration rate was analyzed by karyotyping. The amounts of telomeric DNA in embryonic cells and lymphocytes were quantified by Quantitative Fluorescence in situ Hybridization method. The chromosome aberration rate in chick embryos significantly differed with maternal age. The chromosome aberration rate increased at early laying period and beyond 70 weeks of maternal age. Therefore, chromosome aberration rate was affected by maternal age due to ovulated oocytes state. However, the amount of telomeric DNA on embryonic cells did not differ significantly with maternal age. Thus, maternal age does not affects telomere quantity in their embryos due to cellular reprograming at early embryonic stage after fertilization.

No abstract