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1.
Rapid prenatal diagnosis of chromosomal aneuploidies by fluorescence in situ hybridization: clinical experience with 4,500 specimens. 总被引:13,自引:2,他引:11
B E Ward S L Gersen M P Carelli N M McGuire W R Dackowski M Weinstein C Sandlin R Warren K W Klinger 《American journal of human genetics》1993,52(5):854-865
Detection of chromosome aneuploidies in uncultured amniocytes is possible using fluorescence in situ hybridization (FISH). We herein describe the results of the first clinical program which utilized FISH for the rapid detection of chromosome aneuploidies in uncultured amniocytes. FISH was performed on physician request, as an adjunct to cytogenetics in 4,500 patients. Region-specific DNA probes to chromosomes 13, 18, 21, X, and Y were used to determine ploidy by analysis of signal number in hybridized nuclei. A sample was considered to be euploid when all autosomal probes generated two hybridization signals and when a normal sex chromosome pattern was observed in greater than or equal to 80% of hybridized nuclei. A sample was considered to be aneuploid when greater than or equal to 70% of hybridized nuclei displayed the same abnormal hybridization pattern for a specific probe. Of the attempted analyses, 90.2% met these criteria and were reported as informative to referring physicians within 2 d of receipt. Based on these reporting parameters, the overall detection rate for aneuploidies was 73.3% (107/146), with an accuracy of informative results for aneuploidies of 93.9% (107/114). Compared to cytogenetics, the accuracy of all informative FISH results, euploid and aneuploid, was 99.8%, and the specificity was 99.9%. In those pregnancies where fetal abnormalities had been observed by ultrasound, referring physicians requested FISH plus cytogenetics at a significantly higher rate than they requested cytogenetics alone. The current prenatal FISH protocol is not designed to detect all chromosome abnormalities and should only be utilized as an adjunctive test to cytogenetics. This experience demonstrates that FISH can provide a rapid and accurate clinical method for prenatal identification of chromosome aneuploidies. 相似文献
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Effects of low-chloride solutions on action potentials of sheep cadiac purkinje fibers 总被引:2,自引:0,他引:2 下载免费PDF全文
The rapid repolarization during phase 1 of the action potential of sheep cardiac purkinje fibers has been attributed to a time- and voltage-dependent chloride current. In part, this conclusion was based on experiments that showed a substantial slowing of phase 1 when larger, presumably impermeant, anions were substituted for chloride in tyrode’s solution. We have re- examined the electrical effects of low-chloride solutions. We recorded action potentials of sheep cardiac purkinje fibers in normal tyrode’s solution and in low-chloride solutions made by substituting sodium propionate, acetylglycinate, methylsulfate, or methanesulfonate for the NaCl of Tyrode’s solution. Total calcium was adjusted to keep calcium ion activity of test solutions equal to that of control solutions. Propionate gave qualitatively variable results in preliminary experiments; it was not tested further. Low-chloride solutions made with the other anions gave much more consistent results: phase 1 and the notch that often occurs between phases 1 and 2 were usually unaffected, and the action potential duration usually increased. The only apparent change in the resting potential was a transient 3-6 mV depolarization when low-chloride solution was first admitted to the chamber, and a symmetrical transient hyperpolarization when chloride was returned to normal. If a time- and voltage-dependent chloride current exists in sheep cardiac purkinje fibers, our results suggest that it plays little role in generating phase 1 of the action potential. 相似文献
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Background
Text-mining can assist biomedical researchers in reducing information overload by extracting useful knowledge from large collections of text. We developed a novel text-mining method based on analyzing the network structure created by symbol co-occurrences as a way to extend the capabilities of knowledge extraction. The method was applied to the task of automatic gene and protein name synonym extraction. 相似文献5.
BACKGROUND: Biochemical testing for pheochromocytoma by measurement of fractionated plasma metanephrines is limited by false positive rates of up to 18% in people without known genetic predisposition to the disease. The plasma normetanephrine fraction is responsible for most false positives and plasma normetanephrine increases with age. The objective of this study was to determine if we could improve the specificity of fractionated plasma measurements, by statistically adjusting for age. METHODS: An age-adjusted metanephrine score was derived using logistic regression from 343 subjects (including 33 people with pheochromocytoma) who underwent fractionated plasma metanephrine measurements as part of investigations for suspected pheochromocytoma at Mayo Clinic Rochester (derivation set). The performance of the age-adjusted score was validated in a dataset of 158 subjects (including patients 23 with pheochromocytoma) that underwent measurements of fractionated plasma metanephrines at Mayo Clinic the following year (validation dataset). None of the participants in the validation dataset had known genetic predisposition to pheochromocytoma. RESULTS: The sensitivity of the age-adjusted metanephrine score was the same as that of traditional interpretation of fractionated plasma metanephrine measurements, yielding a sensitivity of 100% (23/23, 95% confidence interval [CI] 85.7%, 100%). However, the false positive rate with traditional interpretation of fractionated plasma metanephrine measurements was 16.3% (22/135, 95% CI, 11.0%, 23.4%) and that of the age-adjusted score was significantly lower at 3.0% (4/135, 95% CI, 1.2%, 7.4%) (p < 0.001 using McNemar's test). CONCLUSION: An adjustment for age in the interpretation of results of fractionated plasma metanephrines may significantly decrease false positives when using this test to exclude sporadic pheochromocytoma. Such improvements in false positive rate may result in savings of expenditures related to confirmatory imaging. 相似文献
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Genetic affinities of inbred mouse strains of uncertain origin 总被引:5,自引:1,他引:4
Phylogenetic analyses of genetic data arising from 144 gene loci are used
to describe the interrelationships among 24 widely used inbred strains of
mice. An unordered-parsimony analysis gives a cladogram that is virtually
identical to the known genealogy of the mouse strains. A loss-parsimony
analysis is used to evaluate the hypothesis that the observed patterns of
genetic divergence among these 24 strains can be explained by the
segregation of residual heterozygosity arising from a small population of
highly heterozygous mice. The loss-parsimony cladogram is very similar to
both the unordered-parsimony cladogram and the known genealogy of the mice.
The phylogenetic analyses of these 144 loci are integrated with data on the
type and origin of the Y chromosome. Inclusion of the Y-chromosome data
provides additional insights into the genetic composition of several of the
original stocks used to produce the current inbred strains of mice. Ten
strains of uncertain origin are contained in these analyses, including AKR,
BUB, CE, I, NZB, P, RF, SJL, ST, and SWR. SJL is hypothesized to have been
derived from the same Swiss albino stock previously used to produce SWR.
The BUB strain appears to have had a complex origin and shows closest
genetic similarity to SWR and ST. AKR and RF are shown to be closely
related, while the I strain shows greatest genetic similarity to DBA/2 for
the 144 loci. However, I and DBA possess different types of Y chromosome.
The NZB strain shows genetic similarity to several stocks of both U.S. and
European origins. The power of the genetic data used in these analyses
reiterates that inbred strains of mice can be a valuable paradigm for
studies in evolutionary biology.
相似文献
8.
Terry Lerner Gabriella Wright Benjamin Leverone William Dackowski Donna Shook Mary Ann Anderson Katherine Klinger David Callen Gregory Landes 《Mammalian genome》1992,3(2):92-100
To test the feasibility of using cloned NotI sites as markers for physical mapping, we have screened for cosmid clones spanning the NotI sites on human Chromosome (Chr) 16. Fluorescence in situ hybridization analysis of these clones confirms the previously reported cluster of NotI sites on 16p13.3. Methylation status of the cloned NotI sites on genomic DNA was established by hybridization of the cosmids to Southern blots containing EcoRI and EcoRI/NotI digest of genomic DNA. These results indicated that four of six clones included in our study can be used as linking clones for physical mapping. Two clones have NotI sites which are not cleavable in the cell lines tested. In one clone, the NotI site exists as an isolated rare-cutting restriction enzyme site, whereas in the other clone the NotI site appears to be island-related. 相似文献
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ADA WRÓBLEWSKA 《Biological journal of the Linnean Society. Linnean Society of London》2012,105(4):761-775
In the last decade a number of studies has illustrated quite different phylogeographical patterns amongst plants with a northern present‐day geographical distribution, spanning the entire circumboreal region and/or circumarctic region and southern mountains. These works, employing several marker systems, have brought to light the complex evolutionary histories of this group. Here I focus on one circumboreal plant species, Chamaedaphne calyculata (leatherleaf), to unravel its phylogeographical history and patterns of genetic diversity across its geographical range. A survey of 29 populations with combined analyses of chloroplast DNA (cpDNA), internal transcribed spacer (ITS) and AFLP markers revealed structuring into two groups: Eurasian/north‐western North American, and north‐eastern North American. The present geographical distribution of C. calyculata has resulted from colonization from two putative refugial areas: east Beringia and south‐eastern North America. The variation of chloroplast DNA (cpDNA) and ITS sequences strongly indicated that the evolutionary histories of the Eurasian/north‐western North American and the north‐eastern North American populations were independent of each other because of a geographical disjunction in the distribution area and ice‐sheet history between north‐eastern and north‐western North America. Mismatch analysis using ITS confirmed that the present‐day population structure is the result of rapid expansion, probably since the last glacial maximum. The AFLP data revealed low genetic diversity of C. calyculata (P = 19.5%, H = 0.085) over the whole geographical range, and there was no evidence of loss of genetic diversity within populations in the continuous range, either at the margins or in formerly glaciated and nonglaciated regions. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105 , 761–775. 相似文献
10.
Expression of completely gamma-carboxylated and beta-hydroxylated recombinant human vitamin-K-dependent protein S with full biological activity 总被引:1,自引:0,他引:1
Human anticoagulant vitamin-K-dependent protein S was expressed in mouse C127 cells using a bovine papilloma virus vector system. A full-length cDNA construct was introduced into the vector in the 5' untranslated region of the mouse metallothionein-I gene. Transfected cells expressed approximately 10 micrograms/ml of the recombinant protein which was purified by ion-exchange chromatography followed by affinity chromatography using Ca2(+)-dependent monoclonal antibodies against the region of protein S containing 4-carboxyglutamic acid. Recombinant protein S was structurally and functionally similar to protein S purified from plasma. On SDS/polyacrylamide-gel electrophoresis recombinant protein S had a slightly higher molecular mass than plasma protein S. After treatment with endoglycosidase F, the proteins comigrated suggesting the observed molecular mass difference to be due to alterations in the N-linked carbohydrate side chains. Recombinant and plasma protein S demonstrated identical amino-terminal sequences, similar amino acid composition and number of 4-carboxyglutamyl and 3-hydroxyaspartyl/asparaginyl residues. Recombinant protein S had the same affinity for Ca2+ as protein S from plasma and the two proteins had the same activated protein C cofactor activity in a functional assay. In addition, both forms of protein S formed complexes with C4b-binding protein with the same apparent Kd. Protein S is the most extensively post-translationally modified vitamin-K-dependent protein, and all the modifications were carried out in the recombinant DNA system yielding a recombinant protein S with full biological activity. 相似文献