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排序方式: 共有7872条查询结果,搜索用时 46 毫秒
81.
Curtas AR Wood HG Allaire PE McDaniel JC Day SW Olsen DB 《ASAIO journal (American Society for Artificial Internal Organs : 1992)》2002,48(5):552-561
To finalize the design of the next generation of the HeartQuest left ventricular assist device, a suitable impeller had to be designed and tested. The new prototype was based on calculations and test results of previous designs, but required several changes to decrease the size. For most pump designs, this is a simple matter of altering impeller geometry and rotational speed to achieve the desired pressure rise and flow rate. However, this particular pump was limited by housing geometry and the magnetic bearings that support the impeller. Without much freedom in the overall impeller size, the only parameters open to the designers were the blade profiles and the rotating speed. Rather than build several candidates and test them in a rig at enormous cost, computational models of several designs were tested and analyzed. This not only saved money, but also sped up the development time for the project. The computer models were developed in TASCflow, a computational fluid dynamics software package from AEA Technologies. This paper analyzes the data from several of the selected models, paying close attention to pumping performance and general trends from specific design changes. 相似文献
82.
An IFN-beta-albumin fusion protein that displays improved pharmacokinetic and pharmacodynamic properties in nonhuman primates. 总被引:6,自引:0,他引:6
Cynthia Sung Bernardetta Nardelli David W LaFleur Erich Blatter Marta Corcoran Henrik S Olsen Charles E Birse Oxana K Pickeral Junli Zhang Devanshi Shah Gordon Moody Solange Gentz Lisa Beebe Paul A Moore 《Journal of interferon & cytokine research》2003,23(1):25-36
The long half-life and stability of human serum albumin (HSA) make it an attractive candidate for fusion to short-lived therapeutic proteins. Albuferon (Human Genome Sciences [HGS], Inc., Rockville, MD) beta is a novel recombinant protein derived from a gene fusion of interferon-beta (IFN-beta ) and HSA. In vitro, Albuferon beta displays antiviral and antiproliferative activities and triggers the IFN-stimulated response element (ISRE) signal transduction pathway. Array analysis of 5694 independent genes in Daudi-treated cells revealed that Albuferon beta and IFN-beta induce the expression of an identical set of 30 genes, including 9 previously not identified. In rhesus monkeys administered a dose of 50 microg/kg intravenously (i.v.) or subcutaneously (s.c.) or 300 microg/kg s.c., Albuferon beta demonstrated favorable pharmacokinetic properties. Subcutaneous bioavailability was 87%, plasma clearance at 4.7-5.7 ml/h/kg was approximately 140-fold lower than that of IFN-beta, and the terminal half-life was 36-40 h compared with 8 h for IFN-beta. Importantly, Albuferon beta induced sustained increases in serum neopterin levels and 2',5' mRNA expression. At a molar dose equivalent to one-half the dose of IFN-beta, Albuferon beta elicited comparable neopterin responses and significantly higher 2',5'-OAS mRNA levels in rhesus monkeys. The enhanced in vivo pharmacologic properties of IFN-beta when fused to serum albumin suggest a clinical opportunity for improved IFN-beta therapy. 相似文献
83.
J-L Stievenart EA Cabanis P Menard J Knoplioch A Lopez J Tamraz M-T Iba-Zizen B Philippe G Prevost J-C Bertrand 《Surgical and radiologic anatomy : SRA》1993,15(1):47-54
Summary In view of the variety of 3D representation techniques, a clinical study was carried out in order to evaluate their respective usefulness. It appears that a single technique cannot be claimed to be valid for all clinical situations and that a combination of representations brings more relevant information. Among the different techniques a clear delineation must be established between those which allow the accurate definition of landmarks (multiplanar reformation, surface representation), and those which do not (integral shading, reconstructed radiology). The main point is the possibility to recognize anatomical landmarks on these latter modes and to choose oblique cut planes in relation to them. Visualization quality is strongly dependent upon the acquisition protocol which must provide a spatial resolution as isotropic as possible.
Une revue de différents modes de visualisation en haute résolution d'un objet volumique avec des applications
Résumé Face à la variété des techniques de représentation 3D une étude clinique a été conduite pour évaluer leurs utilités respectives. Il apparait qu'une technique unique ne peut pas convenir à toutes les situations cliniques et qu'une combinaison de différents modes de présentation apporte une information plus pertinente. Parmi les différentes techniques une distinction claire doit être établie entre celles qui autorisent la prise de repères précis (reformatage multiplanaire, représentation de surface), et celles qui ne le permettent pas (ombrage intégral, radiologie reconstruite). Le point principal est la possibilité de reconnaître des repères anatomiques sur ces derniers modes et de choisir des plans de coupe en relation avec eux. La qualité de la visualisation dépend étroitement du protocole d'acquisition qui doit fournir une résolution aussi isotrope que possible.相似文献
84.
Igarashi S; Takiyama Y; Cancel G; Rogaeva EA; Sasaki H; Wakisaka A; Zhou YX; Takano H; Endo K; Sanpei K; Oyake M; Tanaka H; Stevanin G; Abbas N; Durr A; Rogaev EI; Sherrington R; Tsuda T; Ikeda M; Cassa E; Nishizawa M; Benomar A; Julien J; Weissenbach J; Tsuji S 《Human molecular genetics》1996,5(7):923-932
Machado-Joseph disease (MJD) is an autosomal dominant neurodegenerative
disorder caused by unstable expansion of a CAG repeat in the MJD1 gene at
14q32.1. To identify elements affecting the intergenerational instability
of the CAG repeat, we investigated whether the CGG/GGG polymorphism at the
3' end of the CAG repeat affects intergenerational instability of the CAG
repeat. The [expanded (CAG)n-CGG]/[normal (CAG)n- GGG] haplotypes were
found to result in significantly greater instability of the CAG repeat
compared to the [expanded (CAG)n- CGG]/[normal (CAG)n-CGG] or [expanded
(CAG)nGGG]/[normal (CAG)n-GGG] haplotypes. Multiple stepwise logistic
regression analysis revealed that the relative risk for a large
intergenerational change in the number of CAG repeat units (< -2 or >
2) is 7.7-fold (95% CI: 2.5-23.9) higher in the case of paternal
transmission than in that of maternal transmission and 7.4-fold (95% CI:
2.4-23.3) higher in the case of transmission from a parent with the
[expanded (CAG)n-CGG]/[normal (CAG)n-GGG] haplotypes than in that of
transmission from a parent with the [expanded (CAG)n-CGG]/[normal
(CAG)n-CGG] or [expanded (CAG)n- GGG]/[normal (CAG)n-GGG] haplotypes. The
combination of paternal transmission and the [expanded (CAG)n-CGG]/[normal
(CAG)n-GGG] haplotypes resulted in a 75.2-fold (95% CI: 9.0-625.0) increase
in the relative risk compared with that of maternal transmission and the
[expanded (CAG)n-CGG]/[normal (CAG)n-CGG] or [expanded (CAG)n- GGG]/[normal
(CAG)n-GGG] haplotypes. The results suggest that an inter- allelic
interaction is involved in the intergenerational instability of the
expanded CAG repeat.
相似文献
85.
Reproducibility of histomorphologic diagnoses with special reference to the kappa statistic 总被引:14,自引:0,他引:14
H Svanholm H Starklint H J Gundersen J Fabricius H Barlebo S Olsen 《APMIS : acta pathologica, microbiologica, et immunologica Scandinavica》1989,97(8):689-698
Systems for classification and grading used in pathology should ideally be biologically meaningful and at least be reproducible from one pathologist to another. A statistical method to evaluate reproducibility (non-chance agreement) for several observers using nominal or ordinal categories has been developed and refined over the past few decades--the kappa statistic. A high level of observed agreement among different pathologists can either signify a high level of reproducibility, if agreement by chance is low, or express a low level of reproducibility, if agreement by chance is almost as high as the observed agreement. Therefore, the observed agreement says nothing in itself, unless it is low. The kappa value, however, indicates how much better the observers are compared to a throw of the dice, and therefore gives the real credit to the agreement which was found. We have developed a user-friendly computer program for calculating inter- and intra-observer agreement of 2 or more observers. By calculating associations between different categories and different observers, the statistic furthermore obtains a function close to the parameter of accuracy. We recommend the use of the above method before a set of nominal or rank scale parameters are used for deciding prognosis and treatment of patients. By submitting a diskette the computer program will be available at no cost. 相似文献
86.
P E Mortensen J Olsen P Sejrsen J Bülow S Edelfors 《Acta physiologica Scandinavica》1990,139(2):311-317
In 11 anaesthetized pigs a laparotomy was performed and the mucosal and submucosal blood flow rate in the small intestine of the pig was determined by a local application of 133Xe and by 6.5-microns radioactive microspheres. The 133Xe washout plotted in a semilogarithmic diagram showed a multiexponential configuration. As localization studies of 133Xe in the intestinal mucosa showed a constant high concentration of 133Xe in the luminal part of the mucosa due to shunting by diffusion, the initial slope of the 133Xe washout was used for blood flow determination in the mucosa/submucosa. There was a good relationship between blood flow determined by the two techniques. The correlation coefficient, R, between the two techniques was 0.89. 相似文献
87.
Functional consequences of ROMK mutants linked to antenatal Bartter's syndrome and implications for treatment 总被引:4,自引:0,他引:4
The antenatal variant of Bartter's syndrome is an autosomal recessive
kidney disease characterized by polyhydramnios, premature delivery,
hypokalemic alkalosis and hypercalciuria. It is genetically heterogeneous,
having been linked recently to mutations in an ATP- sensitive, renal outer
medullary K+channel, ROMK, and earlier to mutations in the Na-K-2Cl
co-transporter, NKCC2. We characterized four of the mutations reported in
three heterozygous ROMK variants of antenatal Bartter's and found that each
expressed a distinct phenotype in Sf9 cells. One mutation expressed normal
function and appears to be an allelic polymorphism. The other three
mutations produced channels with significantly reduced K+fluxes. However,
the mechanisms in each case were different and reflected abnormalities in
phosphorylation, proteolytic processing or protein trafficking. The
different mechanisms may be important in the design of appropriate therapy
for patients with this disease.
相似文献
88.
Detecting pre-ovulatory luteinizing hormone surges in urine 总被引:2,自引:1,他引:2
Kesner JS; Knecht EA; Krieg EF Jr; Wilcox AJ; O'Connor JF 《Human reproduction (Oxford, England)》1998,13(1):15-21
The study objectives were to determine (i) if pre-ovulatory luteinizing
hormone (LH) surges, undetected in urine by two immunoradiometric assays
(IRMA), were detectable by an ultrasensitive immunofluorometric assay
(IFMA) and (ii) the influence of creatinine adjustment on the detection and
timing of the urinary LH surges. Daily urine specimens were contributed by
healthy 25-36 year old volunteers during 14 ovulatory menstrual cycles for
an epidemiological study conducted in 1983-1985. Specimens were selected as
having been previously assayed by two IRMA without consistently detecting
LH surges. These urine specimens were remeasured using an IFMA and adjusted
for creatinine concentration. IFMA measurements revealed unambiguous LH
surges in all cycles. Adjusting IRMA urinary LH values for creatinine
concentrations revealed previously undetected LH surges in four of eight
cycles. Creatinine adjustment also altered the timing of IRMA and IFMA LH
surges by 1-5 days. These results demonstrate an IFMA that detects pre-
ovulatory LH surges in unpreserved, frozen urine from cycles where such
surges were previously undetectable. Further, creatinine adjustment can
markedly affect detection and timing of the onset and peak of the urinary
LH surge. While our analysis suggests that this adjustment improves the
validity of the LH measure, this requires further investigation.
相似文献
89.
Subfecundity is a frequent and serious problem that may sometimes be preventable, but we need to know more about its determinants. Different epidemiologic designs are available. The best of these use prospectively collected data from the population, but they are time consuming, expensive and often hampered by low-participation rates. Most patients undergoing infertility treatment are closely monitored for clinical reasons, making it feasible to use secondary data to study the period from conception to implantation and pregnancy. In spite that infertility patients are highly selected, there are specific exposure-effect relations that can be studied in cohorts of infertility patients. These patients offer a potentially useful setting for studying exposures that operate late in fertilization, whereas the designs may be inadequate to identify exposures that cause reduced sperm counts, anovulation and total occlusion. The clinical sampling and the treatment set limitations for what can be studied. In certain situations, infertile patients can, however, provide useful epidemiologic evidence for learning about the causes of subfecundity. 相似文献
90.