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1.
The ATP-binding-cassette transmembrane transporters (ABC transporters)
known from vertebrates belong to four major subfamilies: (1) the P-
glycoproteins (Pgp); (2) the cystic fibrosis transmembrane conductance
regulators (CFTR); (3) the Tap proteins encoded with the major
histocompatibility complex of mammals; and (4) the peroxisomal membrane
proteins. Both Pgp and CFTR have a structure suggesting a past internal
gene duplication; a phylogenetic analysis indicated that these duplications
occurred independently, while an independent tandem gene duplication
occurred in the case of the Tap family. Both the Pgp and Tap proteins show
evidence of relationship to bacterial ABC transporters lacking internal
duplication, and both are significantly more closely related to the HlyB
and MsbA families of transporters from purple bacteria than they are to ABC
transporters from nonpurple bacteria. The simplest hypothesis to explain
this observation is that eukaryotic Pgp and Tap genes are descended from a
mitochondrial gene or genes that were subsequently translocated to the
nuclear genome. The Pgp genes of eukaryotes are characterized by a
remarkable degree of convergent evolution between the ATP-binding cassettes
of their N- terminal and C-terminal halves, whereas no such convergence is
seen between the two halves of CFTR genes or between the duplicated Tap
genes. Exon 13 of the CFTR gene, which encodes a putative regulatory domain
not found in other ABC transporters apart from CFTR, showed high levels of
both synonymous and nonsynonymous difference in comparisons among different
mammalian species, suggesting that this region is a mutational hot spot.
相似文献
2.
3.
X Xiao G Hintermann AL Demanin J Piret 《Journal of industrial microbiology & biotechnology》1996,16(4):261-262
Streptomyces glaucescens is shown to possess -lactamase activity which is inhibitable by clavulanate. This is important in regard to its use as a cloning host for enzymes of \-lactam biosynthesis. 相似文献
4.
Dynamic BTPS correction factors for spirometric data 总被引:1,自引:0,他引:1
5.
ERIC S. BONO PATRICK SMOLINSKI AL CASAGRANDA JUNDE XU 《Computer methods in biomechanics and biomedical engineering》2013,16(2):125-131
The Shear-slip Mesh Update Method (SSMUM) is being used in flow simulations involving large but regular displacements of one or more boundaries of the computational domain. We follow up the earlier discussion of the method with notes on practical implementation aspects. In order to establish a benchmark problem for this class of flow problems, we define and report results from a two-dimensional viscous flow around a rotating stirrer in a square chamber. The application potential of the method is demonstrated in the context of biomedical design problem, as we perform an analysis of blood flow in a centrifugal left ventricular assist device, or blood pump, which involves a rotating impeller in a non-axisymmetric housing. 相似文献
6.
7.
Objective: Recent studies have suggested that a relationship between adiponectin and sex hormone, prolactin, and insulin‐like growth factor levels could be important for breast cancer risk and insulin sensitivity. Therefore, we assessed the relationship of adiponectin with plasma concentrations of estrone; estradiol; estrone sulfate; testosterone; androstenedione; dehydroepiandrosterone (DHEA); dehydroepiandrosterone sulfate (DHEAS); sex hormone binding globulin (SHBG); prolactin; insulin‐like growth factor (IGF‐1); its binding protein, IGF binding protein 3 (IGFBP‐3); c‐peptide; and IGF binding protein 1 (IGFBP‐1) among 360 postmenopausal women not taking postmenopausal hormones from the Nurses’ Health Study. Research Methods and Procedures: Multivariate models were adjusted for physical activity, alcohol consumption, age at blood draw, age at first birth/parity, fasting status, and time of day of blood draw; a separate model was additionally adjusted for BMI at blood draw. Results: Estrogens were inversely associated with adiponectin levels; however, except for free estradiol, these associations were substantially attenuated after adjustment for BMI. Free estradiol levels were 27% lower among women in the top vs. bottom quartile of adiponectin levels. No consistent associations were observed for the androgens, prolactin, IGF‐1, and IGFBP‐3. However, SHBG, c‐peptide, and IGFBP‐1 were strongly and independently associated with adiponectin levels (r = 0.29, ?0.30, 0.24, respectively). Conclusion: With the exceptions of SHBG, c‐peptide, and IGFBP‐1, the studied analytes were modestly associated with adiponectin and the associations were, in large part, mediated by body fat. 相似文献
8.
HENRY SILVERMAN BABIKER AHMED SAMAR AJEILET SUMAIA AL‐FADIL SUHAIL AL‐AMAD HADIR EL‐DESSOUKY IBRAHIM EL‐GENDY MOHAMED EL‐GUINDI MUSTAFA EL‐NIMEIRI RANA MUZAFFAR AZZA SALEH 《Developing world bioethics》2010,10(2):70-77
To help ensure the ethical conduct of research, many have recommended educational efforts in research ethics to investigators and members of research ethics committees (RECs). One type of education activity involves multi‐day workshops in research ethics. To be effective, such workshops should contain the appropriate content and teaching techniques geared towards the learning styles of the targeted audiences. To ensure consistency in content and quality, we describe the development of a curriculum guide, core competencies and associated learning objectives and activities to help educators organize research ethics workshops in their respective institutions. The curriculum guide is divided into modular units to enable planners to develop workshops of different lengths and choose content materials that match the needs, abilities, and prior experiences of the target audiences. The content material in the curriculum guide is relevant for audiences in the Middle East, because individuals from the Middle East who participated in a Certificate Program in research ethics selected and developed the training materials (e.g., articles, powerpoint slides, case studies, protocols). Also, many of the activities incorporate active‐learning methods, consisting of group work activities analyzing case studies and reviewing protocols. The development of such a workshop training curriculum guide represents a sustainable educational resource to enhance research ethics capacity in the Middle East. 相似文献
9.
Bansal SK Layloff T Bush ED Hamilton M Hankinson EA Landy JS Lowes S Nasr MM St Jean PA Shah VP 《AAPS PharmSciTech》2004,5(1):151-158
The purpose of the use of analytical instruments is to generate reliable data. Instrument qualification helps fulfill this
purpose. No authoritative guide exists that considers the risk of instrument failure and combines that risk with users' scientific
knowledge and ability to use the instrument to deliver reliable and consistent data. In the absence of such a guide, the qualification
of analytical instruments has become a subjective and often fruitless document-generating exercise.
Taking its cue from the new FDA initiative, “Pharmaceutical GMP's for the 21st Century,” an efficient, science- and risk-based
process for AIQ was discussed at a workshop on analytical instrument qualification. This report represents the distillate
of deliberations on the complicated issues associated with the various stages of analytical instrument qualification. It emphasizes
AIQ's place in the overall process of obtaining quality reliable data from analytical instruments and offers an efficient
process for its performance, one that focuses on scientific value rather than on producing documents. Implementing such a
process should remove ambiguous interpretations by various groups. 相似文献
10.
Phylogenetic tests of the hypothesis of block duplication of homologous genes on human chromosomes 6, 9, and 1 总被引:8,自引:1,他引:7
There are 10 gene families that have members on both human chromosome 6
(6p21.3, the location of the human major histocompatibility complex [MHC])
and human chromosome 9 (mostly 9q33-34). Six of these families also have
members on mouse chromosome 17 (the mouse MHC chromosome) and mouse
chromosome 2. In addition, four of these families have members on human
chromosome 1 (1q21-25 and 1p13), and two of these have members on mouse
chromosome 1. One hypothesis to explain these patterns is that members of
the 10 gene families of human chromosomes 6 and 9 were duplicated
simultaneously as a result of polyploidization or duplication of a
chromosome segment ("block duplication"). A subsequent block duplication
has been proposed to account for the presence of representatives of four of
these families on human chromosome 1. Phylogenetic analyses of the 9 gene
families for which data were available decisively rejected the hypothesis
of block duplication as an overall explanation of these patterns. Three to
five of the genes on human chromosomes 6 and 9 probably duplicated
simultaneously early in vertebrate history, prior to the divergence of
jawed and jawless vertebrates, and shortly after that, all four of the
genes on chromosomes 1 and 9 probably duplicated as a block. However, the
other genes duplicated at different times scattered over at least 1.6
billion years. Since the occurrence of these clusters of related genes
cannot be explained by block duplication, one alternative explanation is
that they cluster together because of shared functional characteristics
relating to expression patterns.
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