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Conditions have been optimized for SPE-HPTLC determination of catechins in different clones of the genus Salix . A mixture of catechin, epicatechin, gallocatechin, and catechin gallate standards was separated on silica gel RP-18WF 254 plates with acetonitrile-water-formic acid, 20 + 80 + 6 ( v/v ), as mobile phase. The best separation of catechin and epicatechin was achieved by multiple gradient development (MGD) with increasing concentrations of acetonitrile (from 20 to 22%) in the water-formic acid mixture. UV detection at λ = 282 nm and λ = 500 nm (after derivatization with vanillin-H 3 PO 4 ) were compared for estimation of catechin content. Catechin only was detected in the willow extracts examined. The catechin content of the clones investigated varied between 68.75 and 427.55 mg per 100 g dried plant material.

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Abstract  

Membranes of latex extracted of the seringueira tree (Hevea brasiliensis), genetically improved by selection and statistics methods, were prepared by air drying a 10 mL suspension of the ammonia in latex 10% (v/v). TG-DTG and DSC curves were used to characterize the membranes. Thermal stability and thermal decomposition of these compounds were analyzed. The results obtained show no differences among latex from different clones.

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Abstract  

Human AFP was used as an antigen for the development of monoclonal antibodies by the hybridoma technique. Balb/c mice were immunized with highly purified AFP. The preparation of I125-AFP was carried out by lactoperoxidase oxidation method, preparation of AFP standards was carried out from cord sera. The antibody titer of the serum was tested by RIA-AFP system. The spleen of the immunized Balb/c was fused with Sp20 mouse myeloma cells. The cells from the positive hybridomas were cloned twice using limiting dilution method. Eleven stable clones were thus established for secreting monoclonal antibodies to AFP. Cells in this growth phase were chosen for freezing.

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Abstract  

The RAYGUN gamma-ray analysis code (a descendant of GAMANAL and GRPANL) has been converted from FORTRAN IV to RATFOR and ported to the IBM PC environment. The history of the code and some of the problems encountered during the conversion are discussed. The converted code was then used to analyze the IAEA G-1 Intercomparison Spectra as one measure of the codes performance. The results of the analyses showed that although the intrinsic peak finding and multiplet resolution capabilities of the code are a bit weak, the UPPER-LIMIT and LIBRARY-SEARCH options work quite well. When appropriate gamma-ray libraries are created, the overall performance of the code is quite satisfactory. The RAYGUN code runs on an IBM PC or clone with 256 Kbytes of RAM.

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Abstract  

Tree rings and needles of young spruce clones from the immission area of the Al-refinery Ranshofen (Upper Austria), which had ceased production in 1992, were investigated by INAA. Short time irradiation was performed for determining, Al, Mn, Ca and Cl, while the elements Na, K, Rb, Ba, Zn, Fe, Sc, Cr, Co, Br and in some samples also Ca were determined via middle- and long-lived radioisotopes. Irradiation and counting conditions are given. Accuracy and sensitivity are sufficient to describe the trends of the element concentrations in needles and with the exception of Cr, Sc and Br, in tree rings. Ca-concentrations derived from49Ca (short-time irradiation) and47Ca (long-time irradiation) are compared and show good agreement Additionally Mg was determined in some samples by ICP-AES and if possble, by INAA. The results are compared.

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Journal of Radioanalytical and Nuclear Chemistry
Authors:
Gu-Cai Li
,
Duan-Zhi Yin
,
Deng-Feng Cheng
,
Ming-Qiang Zheng
,
Yan-Jiang Han
,
Han-Chen Cai
,
Jiao-Yun Xia
,
Sheng Liang
,
Wan-Bang Xu
, and
Yong-Xian Wang

Abstract  

3-(4-[18F]fluorobenzyl)-8-hydroxy-1,2,3,4-tetrahydrochromeno[3,4-c]pyridin-5-one ([18F]FHTP) was in vitro and in vivo evaluated as a putative dopamine D4 receptor radioligand. Its inhibition constant (K i ) for cloned human dopamine D4.2 receptor was determined to be 2.9 nM and it displayed a 2000-fold D4-selectivity over the D2long subtype. Its partition coefficient (logP) was measured to be 1.11. Biodistribution, blocking distribution and metabolism studies in rats demonstrated that the specific distribution of [18F]FHTP in brain regions, suggesting that [18F]FHTP may be a suitable PET imaging agent for in vivo studies of the dopamine D4 receptor.

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Abstract  

Latex collected from natural rubber trees forming membranes can be used as biomaterials in several fields being the temperature a key parameter. Thermogravimetry (TG) coupled to Fourier transform infrared spectroscopy (FTIR) is a useful technique to investigate the thermal degradation of both latex and cast films (membranes), wich were obtained from Hevea brasiliensis (RRIM 600 clone) and used without stabilization. The membranes were prepared by casting the latex onto a glass substrate at 65°C for 6 h. The thermal degradation was followed by FTIR spectra acquisition along the process, allowing the identification of the gaseous components evolved upon the thermal treatment. According to TG measurements, the main processes of thermal degradation of the latex and membranes occur at three temperature intervals for both.

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Prions of the baker’s yeast Saccharomyces cerevisiae allow for the inheritance of complex traits based solely on the acquisition of cytoplasmic protein aggregates and confer distinctive phenotypes to the cells which harbor them, creating heterogeneity within an otherwise clonal cell population. These phenotypes typically arise from a loss-of-function of the prion-forming protein that is unable to perform its normal cellular function( s) while sequestered in prion amyloid aggregates, but the specific biochemical consequences of prion infection are poorly understood. To begin to address this issue, we initiated a direct investigation into the potential control that yeast prions exert over fungal lipid content by utilizing the prions [URE3] and [PSI +], the first two prions discovered in yeast. We utilized silica gel high-performance thin-layer chromatography (HPTLC)—densitometry to conduct pair-wise quantifications of the relative levels of free sterols, free fatty acids, and triacylglycerols [petroleum ether—diethyl ether—acetic acid (80:20:1) mobile phase, phosphomolybdic acid (PMA) detection reagent]; steryl esters and squalene (hexane—petroleum ether—diethyl ether—acetic acid (50:20;5:1), PMA]; and phosphatidylethanolamine, phosphatidylcholine, and phosphatidylinositol (chloroform– diethyl ether—acetic acid (65:25:4.5), cupric sulfate—phosphoric acid) in otherwise clonal prion-infected ([PSI +] or [URE3]) and prion-free ([psi ] or [ure-o]) cells in two growth phases: log-phase and stationary phase. Our analysis revealed multiple statistically significant differences (p < 0.00625) between prion-infected and prion-free cells. Interestingly, prion-induced changes varied dramatically by growth phase, indicating that prions exert differential influences on cell physiology between log and stationary growth. Further experimental replication and extension of the analysis to other prions is expected to resolve additional physiological effects of prion infection. This investigation demonstrates that HPTLC—densitometry is an effective method for studying prion-induced alterations in lipid content in yeast.

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Abstract  

Due to the increasing search for alternative sources of natural rubber (NR) whose properties are similar to Hevea brasiliesis, several sources have been studied in the past few years. Among them, Mangabeira (Hancornia speciosa Gomes), which is native to Amazon rainforest and other regions of Brazil, has a potential as another viable rubber source. As a continuation of a series of comparative studies between Hancornia and Hevea (clone RRIM 600) these two species by our research team, their thermal behavior was analyzed by thermogravimetry (TG) using Flynn–Wall–Ozawa’s approach in order to obtain kinetic parameters (reaction order, pre-exponential factor and activation energy) of the decomposition process. Results indicated that the thermal behavior of NR from Hancornia was comparable to Hevea with some differences observed as follows: reaction order for Hancornia was higher than for Hevea at the beginning of degradation and very close for temperatures over 350 °C; activation energy and pre-exponential factor had the same trend, i.e., increased with increasing degree of conversion remaining almost constant between 20 and 70% and then increasing for higher degrees, although Hevea was slightly more thermally stable than Hancornia. These major influences in the degradation process in the early stage are attributed to differences in non-rubber constituents present in these two species.

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JPC - Journal of Planar Chromatography - Modern TLC
Authors:
Krisztina Boór
,
Zsolt Rónai
,
Mária Sasvári-Székely
,
Péter Gaszner
, and
Huba Kalász

2001 22 1102 1105 J. Sambrook, E.F. Fritsch , and T. Maniatis , in: Molecular Cloning, Cold Spring

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