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971.
H Schenone M Contreras P Salinas L Sandoval J Pérez-Olea A Rojas F Solís F Villarroel 《Boletín chileno de parasitología》1992,47(3-4):84-85
To each of 11,161 randomly taken people from urban and peri-urban localities of the first seven regions of Chile (geographic area of distribution of Chagas' disease in the country), with negative serology for Chagas' disease, an indirect hemagglutination test (IHAT) for toxoplasmosis and an EKG were practiced. The IHAT for toxoplasmosis resulted positive in 3,519 individuals (31.5%). The EKG showed alterations in 10.9% of the IHAT positive individuals and in 7.9% of the IHAT negative ones. This difference between the proportion of altered EKG in IHAT positive people and altered EKG in those with negative IHAT is statistically significative with p < 0.001. These results suggest the convenience of considering toxoplasmosis as a cause of chronic myocardiopathy in epidemiological studies on Chagas' disease, since not discard the presence of Toxoplasma gondii infection should overvaluete the magnitude of the impact of Trypanosoma cruzi in the genesis of such a myocardiopathy. 相似文献
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976.
Contreras Miquel Angel Haack Thomas Royo Miriam Giralt Ernest Pons Miquel 《International journal of peptide research and therapeutics》1997,4(1):29-39
Summary Temperature coefficients are widely used as an indication of solvent accessibility to amide protons. Low temperature coefficients
are related to low accessibility and are often interpreted as evidence for intramolecular hydrogen bonding. Conformational
shifts, i.e. the difference between chemical shifts of a particular residue in a structured and in a random-coil conformation,
provide information on secondary structure. In particular, negative CHα conformational shifts are often used to delineate the extent of helical stretches. NH conformational shifts show large oscillations
within a helix that have been interpreted as the result of helix distortions affecting hydrogen bond lengths. In the ocurse
of the study of differnet peptides that adopt a helical structure in the presence of the structure-inducing solvent hexafluoroisopropanol
(HFIP), we have found a strong correlation between temperature coefficients and amide conformational shifts. However, contrary
to the initial expectations, lower temperature coefficients were associated to amide protons involved in longer, and presumably
weaker, hydrogen bonds. The correlation can be explained, however, assuming that, in helical peptides dissolved in HFIP, temperature
affects the chemical shift of amide protons mainly by changing the average length of intramolecular hydrogen bonds and changes
in solvent accessibility play only a secondary role under these experimental conditions. The pattern of temperature coefficients
in helical peptides can therefore be used to identify short or long hydragen bonds causing bending of the helix axis. 相似文献
977.
978.
Asymmetric EcoRI DNA linkers consisting of an AATTC(A)7 dodecamer and a complementary G(T)7 octamer were synthesized. Ligation of such linkers to DNA fragments obviates the need for EcoRI digestion prior to cloning in EcoRI-cleaved vectors. 相似文献
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