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991.
Increasing resistance of Plasmodium falciparum malaria parasites to chloroquine and the dihydrofolate reductase (DHFR) inhibitors pyrimethamine and cycloguanil have sparked renewed interest in the antimalarial drugs WR99210 and proguanil, the cycloguanil precursor. To investigate suggestions that WR99210 and proguanil act against a target other than the reductase moiety of the P. falciparum bifunctional DHFR-thymidylate synthase enzyme, we have transformed P. falciparum with a variant form of human DHFR selectable by methotrexate. Human DHFR was found to fully negate the antiparasitic effect of WR99210, thus demonstrating that the only significant action of WR99210 is against parasite DHFR. Although the human enzyme also resulted in greater resistance to cycloguanil, no decrease was found in the level of susceptibility of transformed parasites to proguanil, thus providing evidence of intrinsic activity of this parent compound against a target other than DHFR. The transformation system described here has the advantage that P. falciparum drug-resistant lines are uniformly sensitive to methotrexate and will complement transformation with existing pyrimethamine-resistance markers in functional studies of P. falciparum genes. This system also provides an approach for screening and identifying novel DHFR inhibitors that will be important in combined chemotherapeutic formulations against malaria. 相似文献
992.
TE Zhurova 《Canadian Metallurgical Quarterly》1981,27(6):20-25
Insulin and glucose-insulin sensitivity of peripheral tissues is studies in patients with thyrotoxicosis of different severity and duration. Three main types of the curves, characterizing exogenic insulin sensitivity, were detected. It was determined that a decrease in insulin sensitivity and insulin resistance prevailed in patients with disturbed glucose tolerance (the doubtful type of glycemic curve, latent diabetes). The results obtained do not eliminate the significance of insulin sensitivity failure in the affection of adaptive characteristics of the pancreatic insulin-producing apparatus in thyrotoxicosis. 相似文献
993.
994.
995.
We studied twenty-five consecutive patients who had a closed tibial fracture to determine whether there was a relationship between compartment pressure and the distance at which the pressure was measured from the site of the fracture. Tissue pressure was measured in all four compartments of the leg at the level of the fracture and at five-centimeter increments proximal and distal to the fracture. The peak pressure was usually found at the level of the fracture and was always located within five centimeters of the fracture. The highest pressures were recorded in the anterior and the deep posterior compartments in twenty patients, including all five of those who had had a fasciotomy. The measured pressure decreased steadily when sampled at increasing distances proximal and distal to the site of the highest recorded pressure. Decreases of twenty millimeters of mercury (2.67 kilopascals) five centimeters adjacent to the site of the peak pressure were common. Compartment syndrome was diagnosed in five patients on the basis of clinical findings, and the diagnosis was confirmed when peak compartment pressures of more than the critical threshold (within twenty millimeters of mercury [2.67 kilopascals] of the diastolic blood pressure) were recorded. Three of these five patients had measured pressures that were less than the critical threshold within five centimeters of the site of the peak pressure. Failure to measure tissue pressure within a few centimeters of the zone of peak pressure may result in a serious underestimation of the maximum compartment pressure. Our results suggest that measurements should be performed in both the anterior and the deep posterior compartments at the level of the fracture as well as at locations proximal and distal to the zone of the fracture to determine reliably the location of the highest tissue pressure in a lower extremity when a compartment syndrome is suspected clinically. The highest pressure should be used in the decision-making process. 相似文献
996.
H Sun LA Valdivia V Subbotin A Aitouche JJ Fung TE Starzl AS Rao 《Canadian Metallurgical Quarterly》1998,18(6):368-371
The Scope of Professional Practice states that nurses may respond to the needs of patients by expanding their practice. Performing skin biopsies for cancer diagnosis is one such area. The provision of appropriate education, training and updating is essential. Clear guidelines for practice are required for all such procedures. 相似文献
997.
Optimal digital filter design is essential for noise suppression in the detection of subtle radiographic bony changes. The purpose of this study was to determine the signal (Ps) and noise (Pn) power spectra of sampled maxillary alveolar bone, to derive the optimal Wiener filter transfer function, H, from sets of Ps and Pn, and to quantify noise suppression through application of this filter. Sixteen standardized radiographs were made of five interproximal bony areas, each area from a separate dry human maxilla. The radiographs were digitized (0.02 mm/pixel resolution) and identical profiles (scan lines) generated between lead markers for each set of films. Ps was calculated from the averaged scan line of each set, Pn was calculated from the difference between the noisy images and the averaged scan line for each set, and an average maxillary H was calculated from the sets of Ps and Pn. Filtering of the 80 noisy sample radiographic profiles with H resulted in a 39% reduction in noise. Application of this digital filter should significantly improve detection of radiographic bony changes in the maxilla. 相似文献
998.
TE Herman A Chines WH McAlister GS Gottesman MC Eddy MP Whyte 《Canadian Metallurgical Quarterly》1997,27(5):436-441
Four members of a family - three of whom have facial features mildly resembling those of the trichorhinophalangeal syndrome, type I, and all of whom manifested appendicular bony prominences similar to trichorhinophalangeal syndrome, type II - were found to have the radiographic findings of metachondromatosis. The radiographic manifestations and evolution of metachondromatosis are depicted in this report. 相似文献
999.