A novel 99mTc labeled complex, [N-[2-((2-oxo-2-(4-(3-phenylpropyl)piperazin-1-yl)ethyl) (2-mercaptoethyl)amino)acetyl]-2-aminoethanethiolato]Technetium(V)
oxide (PPPE-MAMA’-99mTcO) ([99mTc]-2) has been designed and prepared based on the integrated approach. The corresponding rhenium complex (PPPE-MAMA’-ReO)(Re-2) has been prepared and characterized. In vitro competition binding assays show moderate affinity of Re-2 towards σ1 and σ2 receptors with Ki values of 8.67 ± 0.07 and 5.71 ± 1.88 μmol, respectively. Planar images obtained at 0.5 h, 4 h, 20 h after i.v. injection
indicate the accumulation of [99mTc]-2 in MCF-7 human breast tumor bearing mice at 20 h. Furthermore, the accumulation of [99mTc]-2 has been inhibited at 20 h after co-injection of [99mTc]-2 plus haloperidol (1 mg/kg). Biodistribution studies of [99mTc]-2 display an in vivo tumor uptake of 0.14% ± 0.01% ID/g at 24 h post i.v. injection with a tumor/muscle ratio of 6.02 ± 0.87. The above results
suggest that [99mTc]-2, derived from a previously published lead compound, retains certain tumor uptake and affinity for σ receptors. [99mTc]-2 may be used as a basis for further structural modifications to develop tumor imaging agents with high affinity for σ receptors. 相似文献
A new technique of searching the conformational space of transition states was used to explore the cause of the rate acceleration in the gem-dialkyl effect in intramolecular cyclization reactions. Several previous hypotheses were discarded and a new hypothesis was advanced based on this new data. This hypothesis, the “Facilitated Transition” hypothesis, states that increased steric hindrance reduces the overall activation energy by facilitating rotation through the transition state. The older “Reactive Rotamer” hypothesis was eliminated by generating all conformations of the starting materials using the
and
computer programs and demonstrating that no relationship is found between rate increase and a change in the concentration of “reactive rotamers”. 相似文献
A spectral-luminescent analysis has been made of the low-, medium-, and high-molecular mass fractions of sugar cane juice. The presence of pigments was detected in all the fractions. The medium-molecular-mass fraction was distinguished by the most considerable and most diverse composition of the pigments, a substantial contribution to which was made by the products of the alkaline decomposition of sugars. The amounts of pigments in all the fractions of the juice depended on the age of the plant. A pronounced dependence on the age of the plant was characteristic for the medium-molecular-mass fraction.B. I. Stepanov Institute of Physics, Belorussian Academy of Sciences, Minsk. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 456–459, May–June, 1993. 相似文献
GABA is a major neurotransmitter in the central nervous system. Data on GABA and its analogues calculated by using the ab initio and the MNDO method were compared with data obtained experimentally. The structures of GABA analogues calculated by the ab initio method agree well with the experimental data. This finding suggests the high reliability of this method. However, the structures of GABA analogues calculated by the MNDO method reflect only some aspects of the experimental data. Therefore the MNDO method should be used only for carefully selected chemical compounds.
The amino group in GABA and its analogues was proved to be the major active site. The electrostatic potential around the amino group in these compounds seems to be related to their biological activity. The difference in the electrostatic potential between the receptor binding molecules and the neuronal uptake molecules suggests that the structure of post-synaptic receptors might differ from that of uptake receptors. This finding suggests that there are at least two GABA-A receptors. GABA molecules seem to have a high potential for binding to the two receptors because they are highly flexible and can readily change their conformation. These results indicate a high reliability of the data calculated by the molecular orbital method and suggest that this method provides us with useful information that cannot be obtained experimentally. 相似文献
Nine decomposition procedures for soil samples, such as via acid mixtures and fusion in open systems and microwave and autoclave
dissolution (in closed systems under elevated temperature and pressure) were assessed using certified soil reference materials.
The determination of various elements in solutions was performed by FAAS and ICP-OES and the results were compared with certified
values and with direct current arc OES analysis.
Received: 3 March 1997 / Revised: 30 May 1997 / Accepted: 3 June 1997 相似文献
The conformational energies, rotational barrier heights and molecular structures in C(CH2X)4 molecules (X=F, Cl, Br) based on molecular-mechanics calculations have been obtained. The results from these calculations are compared with the experimental gas-phase results. 相似文献
Conclusions The IR spectra of 5- and 8-hydroxyfurocoumarins and their esters, 5,8-disubstituted furocoumarins containing hydroxyl, methoxyl, and alkoxyl groups, and 4,5-dihydrofurocoumarins differ with respect to the intensity and number of the bands in the 1630–1500 cm–1 region of the spectrum. The integral intensities of the absorption bands in this frequency region differ markedly in the derivatives mentioned.Khimiya Prirodnykh Soedinenii, Vol. 5, No. 5, pp. 355–359, 1969 相似文献
Temperature programmed reduction (TPR) has been used to study the redox behavior of Ni(II) ions in nickel sodium mordenite (NiNaM) and decationated nickel mordenite (NiHM). The TPR profiles suggest that Ni(II) ions occupy nonequivalent sites with different cooridination states in the mordenite. The reducibility of Ni(II) depends strongly on the zeolite acidity.