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排序方式: 共有394条查询结果,搜索用时 15 毫秒
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RF Speck K Wehrly EJ Platt RE Atchison IF Charo D Kabat B Chesebro MA Goldsmith 《Canadian Metallurgical Quarterly》1997,71(9):7136-7139
The chemokine receptor CCR5 acts as an essential cofactor for cell entry by macrophage-tropic human immunodeficiency virus type 1 (HIV-1) strains, whereas CXCR4 acts as an essential cofactor for T-cell-line-adapted strains. We demonstrated that the specific amino acids in the V3 loop of the HIV-1 envelope protein that determine cellular tropism also regulate chemokine coreceptor preference for cell entry by the virus. Further, a strong correlation was found between HIV-1 strains classified as syncytium inducing in standard assays and those using CXCR4 as a coreceptor. These data support the hypothesis that progressive adaptation to additional coreceptors is a key molecular basis for HIV-1 phenotypic evolution in vivo. 相似文献
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Routine insulin assays measure not only biologically active insulin but also the relatively inactive propeptides, proinsulin and desdipeptide proinsulin. Such measurements may be misleading if insulin propeptide levels are increased, as has been reported in patients with non-insulin-dependent diabetes mellitus (NIDDM). Inferences regarding insulin resistance, based on hyperinsulinemia, could thus be invalidated where routine insulin assays have been used. We have measured plasma insulin levels using a routine assay, together with measurements of the major circulating insulin propeptides, intact proinsulin and des 31,32proinsulin, in various clinical situations associated with apparently increased insulin levels and insulin resistance. Major increases of insulin propeptide levels relative to insulin levels were not seen in obese subjects or in patients taking oral contraceptives or danazol, or in obese subjects compared with non-obese controls. Although the insulinemic responses observed with routine radioimmunoassay in these situations associated with insulin resistance are not confounded by major changes in the proportion of circulating insulin propeptides, further studies will be necessary to validate investigations in other insulin-resistant states. 相似文献
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E García R Calvo JM Rodríguez-Sasiaín R Jiménez IF Trocóniz E Suárez 《Canadian Metallurgical Quarterly》1995,39(8):1019-1023
The influence of altered protein binding on the neuromuscular effect of atracurium has been studied in rats with experimental inflammation induced by subcutaneous injection of turpentine oil. Doses of atracurium ranging from 0.45 to 1.5 mg.kg-1 were administered to control (n = 30) and to experimental inflammation induced rats (n = 30). Neuromuscular transmission was monitored by recording the twitch tension of the tibialis-anterior muscle elicited by stimulation of the sciatic nerve. Three effect parameters were recorded: (i) intensity of the effect, measured as percentage depression of baseline twitch tension, (ii) duration of drug action (min) and (iii) recovery time (min). The dose-intensity of the effect relationship was modelled using a sigmoid Emax model. The ED50 (effective dose eliciting 50% of the maximum effect) was significantly increased (P < 0.01) in the inflammation group as compared to the control group (0.94 vs. 0.68 mg.kg-1). This change was reflected in a shift of the dose-response curve to the right in the pretreated rats. For equipotent doses ED95 (defined as the effective dose eliciting 95% of maximum effect), no differences were found in recovery time and duration of action between the two groups of rats. Mucoproteins levels (index of alpha 1-acid glycoprotein (AAG) and protein binding were significantly increased in rats with experimental inflammation as compared to control rats. Based on these results, altered serum protein binding of atracurium appears to be responsible, at least in part, for the resistance to atracurium. 相似文献
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OBJECTIVE: To identify possible causes for the increased cardiovascular morbidity and mortality seen in patients with primary hyperparathyroidism. DESIGN: Prospective, blind study. SETTING: University hospital, Sweden. SUBJECTS: 44 Patients with primary hyperparathyroidism and 23 (sex and age matched) control patients with atoxic nodular goitres. INTERVENTIONS: Exploration of the neck with removal of pathological parathyroid glands or thyroid resection. Echocardiography before, and one year after, the operation. MAIN OUTCOME MEASURES: Blood pressure and echocardiographic findings. RESULTS: Hyperparathyroid patients had higher blood pressure and greater left atrial diameter than control patients preoperatively. They also had a significantly lower E:A ratio (mitral flow velocity pattern) than the controls (p = 0.02) indicating a disturbance in early diastolic filling of the left ventricle. The E:A ratio correlated negatively with the systolic blood pressure. 19 of the hyperparathyroid patients (43%) had cardiac calcifications as did 14 (61%) of the controls. Most of calcifications were located in the aortic and mitral valves; only a few patients had calcifications in the myocardium. No significant changes had occurred one year after parathyroidectomy, except for a reduction in systolic blood pressure, in the hyperparathyroid patients. CONCLUSION: Echocardiographic investigation of patients with primary hyperparathyroidism shows early signs of left ventricular dysfunction that may be of clinical importance. 相似文献
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A truncated form of SAG1, the immunodominant surface antigen of Toxoplasma gondii, has been produced in the methylotrophic yeast, Pichia pastoris. By construction, the recombinant protein lacks C-terminal residues 308-336 which, in native SAG1, encompass the glycosylphosphatidylinositol anchorage site. Secretion of anchor-less SAG1 proceeded via the yeast prepro alpha-mating factor signal peptide and yielded two immunoreactive protein species having apparent molecular masses of 31.5 and 34.5 kDa, respectively, and differing only by N-glycosylation of the single Asn-X-Ser site present in the molecule. Purification of the anchor-less SAG1 was achieved by a combination of ion-exchange and size-exclusion chromatographies. N-terminal amino acid sequencing of the products indicated the presence of additional residues glutamic acid--alanine at the N-terminal end of the products. Despite incomplete processing and unnatural glycosylation, anchor-less SAG1 proteins apparently adopted a suitable conformation recognized by monoclonal and human serum-derived antibodies, specific for the native SAG1. In addition, the recombinant anchor-less SAG1 proved competent for inducing proliferation, in vitro, of mononuclear cells from seropositive individuals. Finally, properly adjuvanted anchor-less SAG1 was able to induce protection of mice against a lethal challenge with T. gondii tachyzoites. 相似文献
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Kaio C. S. Rodrigues Ivan I. K. Veloso Marcelo P. A. Ribeiro Antonio J. G. Cruz Alberto C. Badino 《加拿大化工杂志》2021,99(1):401-409
Fast, simple, accurate, and inexpensive methods for obtaining analyte concentration data are desirable in the industrial sector. In the present study, the use of Fourier transform mid‐infrared (FT‐MIR) spectroscopy, combined with partial least squares (PLS) regression, was investigated as a tool for real‐time monitoring of processes of ethanol absorption in glycols. Calibration was performed using simple synthetic samples containing ethanol, water, and monoethylene glycol (MEG) or diethylene glycol (DEG). The PLS models presented excellent performance, with correlation coefficients (R2) close to unity and root‐mean‐square errors of cross‐validation (RMSECV) and prediction (RMSEP) lower than 2% of the calibration data ranges for both analytes (ethanol and water) in both absorbents (MEG and DEG). The monitoring technique developed has potential to be applied in absorption processes and could also be used in other large‐scale unit operations, providing information in real time and enhancing process control. 相似文献
10.
Keiller Nogueira Adriano Alonso Veloso Jefersson Alex dos Santos 《Multimedia Tools and Applications》2016,75(7):4083-4113
In this paper, we present effective algorithms to automatically annotate clothes from social media data, such as Facebook and Instagram. Clothing annotation can be informally stated as recognizing, as accurately as possible, the garment items appearing in the query photo. This task brings huge opportunities for recommender and e-commerce systems, such as capturing new fashion trends based on which clothes have been used more recently. It also poses interesting challenges for existing vision and recognition algorithms, such as distinguishing between similar but different types of clothes or identifying a pattern of a cloth even if it has different colors and shapes. We formulate the annotation task as a multi-label and multi-modal classification problem: (i) both image and textual content (i.e., tags about the image) are available for learning classifiers, (ii) the classifiers must recognize a set of labels (i.e., a set of garment items), and (iii) the decision on which labels to assign to the query photo comes from a set of instances that is used to build a function, which separates labels that should be assigned to the query photo, from those that should not be assigned. Using this configuration, we propose two approaches: (i) the pointwise one, called MMCA, which receives a single image as input, and (ii) a multi-instance classification, called M3CA, also known as pairwise approach, which uses pair of images to create the classifiers. We conducted a systematic evaluation of the proposed algorithms using everyday photos collected from two major fashion-related social media, namely pose.com and chictopia.com. Our results show that the proposed approaches provide improvements when compared to popular first choice multi-label, multi-modal, multi-instance algorithms that range from 20 % to 30 % in terms of accuracy. 相似文献