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991.
The conserved Trp residue within helix 5 of the N-lobe of human serum transferrin (hTF/2N, 40 kDa) has been mutated to Tyr. NMR and CD spectra and energy calculations show that the mutation causes little perturbation of the overall structure of hTF/2N although the chelating agent Tiron removed Fe3+ from the mutant protein about three times faster than from wild-type hTF/2N. 1H-NMR resonances of residues in the Leu122-Trp128-Ile132 hydrophobic patch are assigned both by ring current calculations and with the aid of the mutation. [1H, 15N]-NMR resonances for 11 of the 14 Tyr residues were observed in the spectra of 15N-Tyr-hTF/2N and a resonance for Tyr128 was assignable in spectra of the mutant. The 15N resonance of Y128 was sensitive to oxalate and Ga3+ binding, and Ga3+ binding perturbed 15N resonances for most of the Tyr residues. Since these are well distributed over the N-lobe, it can be concluded that metal-induced structural changes are not merely local to the binding site.  相似文献   
992.
We infected highly susceptible BALB/c and relatively resistant C57BL/6 mice with cloned Trypanosoma congolense and followed the effects of these infections on the circulating parasite numbers, mouse mortality and cytokine expression. C57BL/6 mice controlled their parasitaemia and survived for up to 163 +/- 12 days, while BALB/c mice could not control their parasitaemia and succumbed to the infection within 8.4 +/- 0.5 days. Susceptible BALB/c mice had dramatically higher plasma levels of IL-10 than the resistant C57BL/6 mice from day 7 forward. This was preceded by an earlier and higher level induction of splenic IL-10 messenger RNA (mRNA) expression in the infected BALB/c mice. There was a strong negative correlation between the splenocyte proliferative responses to Concanavalin-A (Con-A) and their production of IL-10 in these infected BALB/c mice. Co-treatment of the Con-A-stimulated spleen cell cultures with monoclonal anti-IL-10 antibodies, but not isotype-matched control antibodies, could completely reverse this suppression of the splenocyte proliferative response. Finally, in three experiments, anti-IL-10 antibody treatment in vivo reduced the peak circulating parasitaemia of infected BALB/c mice by 43% and increased their median survival periods by 38% relative to isotype-matched control antibody-treated mice.  相似文献   
993.
The biological characteristics associated with the morphological diversity of colorectal cancers were investigated to elucidate the causes of this diversity. We examined the proliferative and infiltrating activity of tumor cells, indicated by the mean number of Ag nucleolar organizer region associated proteins (NORs) per nucleus (MNA) and the immunohistochemical response to cathepsin B(CB), in various morphological types of early and advanced colorectal cancers. We examined 73 colorectal cancers obtained by endoscopic and surgical resection. MNA values for sessile and flat-elevated cancers were greater than the values for pedunculate, subpedunculate, and flat-or-depressed early cancers (sessile, P < 0.05). In advanced cancers invading the muscularis propria, protruding cancers showed significantly higher MNA values than small ulcerative cancers (P < 0.01). CB expression increased significantly with the progression of colorectal cancers (P < 0.01), but was not related to morphological diversity in early and advanced cancers. In both sessile and flat cancers, CB expression was higher in moderately differentiated than in well differentiated adenocarcinomas. These results indicate that, in colorectal cancers, protruding early cancers without stalks and protruding advanced cancers have higher proliferative activity than pedunculate or flat early cancers and small ulcerative advanced cancers, respectively, and that CB expression is not associated with morphological diversity, but with depth of invasion and histological differentiation.  相似文献   
994.
995.
OBJECTIVE: To determine whether montelukast, a leukotriene receptor antagonist, attenuates exercise-induced bronchoconstriction (EIB) in 6- to 14-year-old children with asthma. STUDY DESIGN: Double-blind, multicenter, 2-period crossover study. Children (n = 27) with forced expiratory volume in 1 second (FEV1) > or =70% of the predicted value and a fall in FEV1 > or =20% after exercise on 2 occasions. Patients received montelukast (5-mg chewable tablet) or placebo once daily in the evening for 2 days in crossover fashion (at least 4 days between treatment periods). Standardized exercise challenges were performed 20 to 24 hours after the last dose in each period. End points included area above the postexercise percent fall in FEV1 versus time curve (AAC0-60 min), maximum percent fall in FEV1 from pre-exercise baseline, and time to recovery of FEV1 to within 5% of pre-exercise baseline. RESULTS: Montelukast significantly reduced AAC0-60 min (265 vs 590% x min for montelukast and placebo, respectively, P < or = .05; approximately 59% protection relative to placebo) and the maximum percent fall (18% vs 26% for montelukast and placebo, respectively, P < or = .05). Montelukast treatment resulted in a shorter time to recovery (18 vs 28 minutes for montelukast and placebo, respectively, P = .079). CONCLUSIONS: Montelukast attenuates EIB at the end of the dosing interval in 6- to 14-year-old children with asthma.  相似文献   
996.
The relative merits of cooperation and self-interest in an ensemble of strategic interactions can be investigated by using finite random games. In finite random games, finitely many players have finite numbers of actions and independently and identically distributed (iid) random payoffs with continuous distribution functions. In each realization, players are shown the values of all payoffs and then choose their strategies simultaneously. Noncooperative self-interest is modeled by Nash equilibrium (NE). Cooperation is advantageous when a NE is Pareto-inefficient. In ordinal games, the numerical value of the payoff function gives each player's ordinal ranking of payoffs. For a fixed number of players, as the number of actions of any player increases, the conditional probability that a pure strategic profile is not pure Pareto-optimal, given that it is a pure NE, apparently increases, but is bounded above strictly below 1. In games with transferable utility, the numerical payoff values may be averaged across actions (so that mixed NEs are meaningful) and added across players. In simulations of two-player games when both players have small, equal numbers of actions, as the number of actions increases, the probability that a NE (pure and mixed) attains the cooperative maximum declines rapidly; the gain from cooperation relative to the Nash high value decreases; and the gain from cooperation relative to the Nash low value rises dramatically. In the cases studied here, with an increasing number of actions, cooperation is increasingly likely to become advantageous compared with pure self-interest, but self-interest can achieve all that cooperation could achieve in a nonnegligible fraction of cases. These results can be interpreted in terms of cooperation in societies and mutualism in biology.  相似文献   
997.
This two-part series describes the collaborative summer home care nursing program for Korean nurses conducted by the Frances Payne Bolton School of Nursing, Case Western Reserve University, Cleveland, OH, in cooperation with the College of Nursing of Yonsei University, Seoul, Korea. Part I focuses on the development of the collaboration, and part II focuses on the content of the three-week summer home care program and describes related issues and problems as well as suggests solutions. The series concludes with the findings on the program from the postprogram evaluations of students, preceptors, and patients. The collaborative educational program was developed to give Korean home care nurses an opportunity to gain clinical experience in home care nursing in the United States so that they could learn how to deliver better-quality home care for patients and their informal caregivers. Therefore, the program focused on practice-oriented lectures and clinical experiences.  相似文献   
998.
Fever in neutropenic cancer patients is often due to the development of an infection. The standard management of febrile neutropenic patients involves the administration of empiric, hospital-based, parenteral antibiotic therapy. Although this treatment strategy has evolved from experience in high-risk patients with hematological malignancies, in whom bacterial infection can result in substantial morbidity and mortality, it has been adopted for all patients with febrile neutropenia, largely because of the inability of clinicians to reliably distinguish between patients who are at high risk for developing such morbidity/mortality and those who are not. The development of risk-assessment models has facilitated the recognition of high-, moderate-, and low-risk subgroups among febrile neutropenic patients and allows the administration of outpatient antibiotic therapy to the moderate- and low-risk groups, with the same degree of efficacy and safety as hospital-based therapy. Monotherapy with the carbapenems (imipenem/cilastatin and meropenem), with their broad spectrum of activity and established efficacy in high-risk patients, represents realistic options for risk-based treatment of febrile neutropenic patients within and outside the hospital setting.  相似文献   
999.
It has been asserted at times that the human right hemisphere is cognitively inferior to that of a chimpanzee or even a monkey. Related is the even stronger claim that human consciousness, as well as cognition, requires language. These claims are discussed, and counterexamples are presented from both split-brain subjects and patients hemispherectomized in adulthood after customary development as righthanders.  相似文献   
1000.
Maternal tolerance of the fetal allograft remains poorly understood. In humans, expression of the highly polymorphic classical HLA-A and HLA-B loci is suppressed, while expression of the nonclassical HLA-G locus is up-regulated at the maternal-fetal interface. Like other nonclassical MHC class I molecules, HLA-G exhibits limited diversity, but certain characteristics of HLA-G distinguish it from other nonclassical MHC class I molecules: it has a truncated cytoplasmic domain, it is the product of alternatively spliced mRNAs, and it is expressed primarily in the placenta. We have examined MHC class I expression in the placenta of the rhesus monkey to determine whether this animal is a suitable model in which to study the function of HLA-G. Although the rhesus monkey possesses orthologs of many MHC class I and II loci found in humans, the HLA-G ortholog is a pseudogene in this nonhuman primate species. In this study, we report the identification of a novel nonclassical MHC class I locus expressed in the placenta of the rhesus monkey, Mamu-AG (Macaca mulatta-AG). Although unrelated to HLA-G, Mamu-AG encodes glycoproteins with all of the characteristics of HLA-G. These Mamu-AG glycoproteins are limited in their diversity, possess truncated cytoplasmic domains, are the products of alternatively spliced mRNAs, and their expression is restricted to the placenta. Taken together, these data suggest that convergent evolution may have resulted in the expression of a unique nonclassical MHC class I molecule in the rhesus monkey placenta, and that the common structural features of Mamu-AG and HLA-G may be functionally significant.  相似文献   
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