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排序方式: 共有877条查询结果,搜索用时 15 毫秒
1.
2.
Steenbergen EJ; Verhagen OJ; van Leeuwen EF; van den Berg H; von dem Borne AE; van der Schoot CE 《Blood》1995,86(2):692-702
Crosslineage T-cell receptor delta (TCR delta) rearrangements are widely used as tumor markers for the follow up of minimal residual disease in childhood B-precursor acute lymphoblastic leukemia (ALL) by polymerase chain reaction (PCR). The major drawback of this approach is the risk of false-negative results due to clonal evolution. We investigated the stability of V delta 2D delta 3 rearrangements in a group of 56 childhood B-precursor ALL patients by PCR and Southern blot analysis. At the PCR level, V delta 2D delta 3-to-J alpha rearranged subclones (one pathway for secondary TCR delta recombination) were demonstrated in 85.2% of V delta 2D delta 3-positive patients tested, which showed that small subclones are present in the large majority of patients despite apparently monoclonal TCR delta Southern blot patterns. Sequence analysis of V delta 2D delta 3J alpha rearrangements showed a biased J alpha gene usage, with HAPO5 and J alpha F in 26 of 32 and 6 of 32 clones, respectively. Comparison of V delta 2D delta 3 rearrangement status between diagnosis and first relapse showed differences in seven of eight patients studied. In contrast, from first relapse onward, no clonal changes were observed in six patients studied. To investigate the occurrence of crosslineage TCR delta rearrangements in normal B and T cells, fluorescence-activated cell sorter-sorted peripheral blood CD19+/CD3- and CD19-/CD3+ cell populations from three healthy donors were analyzed. V delta 2D delta 3 rearrangements were detected at low frequencies in both B and T cells, which suggests that V delta 2-to-D delta 3 joining also occurs during normal B-cell differentiation. A model for crosslineage TCR delta rearrangements in B-precursor ALL is deduced that explains the observed clonal changes between diagnosis and relapse and is compatible with multistep leukemogenesis of B-precursor ALL. 相似文献
3.
4.
Intracellular ion activities and Cl-transport mechanisms in bullfrog corneal epithelium 总被引:8,自引:0,他引:8
Cell membrane potentials, cell membrane resistances, and intracellular ionic activities were measured in bullfrog corneal epithelium. Equivalent circuit analysis was performed by adding adenosine to the apical surface and assuming that only the apical membrane is initially affected. From single-ion substitutions in the apical bathing solution, the apical membrane was found to have a high Cl- permeability, a low K+ permeability, and an unmeasurably small Na+ permeability. Under control conditions intracellular Cl- activity (aCli) was 22 +/- 2 (SE) mM, intracellular Na+ activity (aNai) was 14 +/- 3 mM, and intracellular K+ activity (aKi) was 106 +/- 5 mM. The electrical potential differences across apical and basolateral membranes were about 50 and 67 mV, respectively, both cell negative. aCli and aKi are higher, whereas aNai is much lower than predicted for equilibrium distribution. Inasmuch as Cl- is transported from the basolateral (stromal) to the apical (tear) side, basolateral entry of this anion is uphill and apical exit is downhill. Basolateral entry is Na+ dependent, as evidenced by a fall of aCli to near-equilibrium values after basolateral Na+ removal. The electrochemical gradient for Cl- efflux across the apical membrane is large enough to account for Cl- transport by electrodiffusion only. Na+ removal from the basolateral solution causes a reversible decrease of apical membrane Cl- permeability. The results support the hypothesis that net transepithelial Cl- transport results from coupled NaCl entry (or an equivalent process) at the basolateral membrane and electrodiffusional Cl- exit at the apical membrane. 相似文献
5.
6.
Sequence comparison of human and yeast telomeres identifies structurally distinct subtelomeric domains 总被引:6,自引:2,他引:6
Flint J; Bates GP; Clark K; Dorman A; Willingham D; Roe BA; Micklem G; Higgs DR; Louis EJ 《Human molecular genetics》1997,6(8):1305-1313
We have sequenced and compared DNA from the ends of three human
chromosomes: 4p, 16p and 22q. In all cases the pro-terminal regions are
subdivided by degenerate (TTAGGG)n repeats into distal and proximal sub-
domains with entirely different patterns of homology to other chromosome
ends. The distal regions contain numerous, short (<2 kb) segments of
interrupted homology to many other human telomeric regions. The proximal
regions show much longer (approximately 10-40 kb) uninterrupted homology to
a few chromosome ends. A comparison of all yeast subtelomeric regions
indicates that they too are subdivided by degenerate TTAGGG repeats into
distal and proximal sub-domains with similarly different patterns of
identity to other non-homologous chromosome ends. Sequence comparisons
indicate that the distal and proximal sub-domains do not interact with each
other and that they interact quite differently with the corresponding
regions on other, non- homologous, chromosomes. These findings suggest that
the degenerate TTAGGG repeats identify a previously unrecognized,
evolutionarily conserved boundary between remarkably different subtelomeric
domains.
相似文献
7.
Thomas F. Knight Steven Sansom Lois Hawk Seymour J. Frankfurt Edward J. Weinman 《Pflügers Archiv : European journal of physiology》1978,373(2):139-143
The ability to excrete a volume of isotonic saline equal to 10% of body weight infused over 60 min, was examined in awake rats and in rats anesthetized with 1 of the 2 agents most commonly used in renal clearance studies, Inactin or Nembutal. Rats anesthetized with Inactin excreted significantly less of the infused sodium during the period of infusion and in the 120-min post-infusion periods as compared to Nembutal-anesthetized rats or awake rats. Following saline infusion, there was a significantly greater decrease in serum protein concentration (25.5±4.7%) in rats anesthetized with Inactin, compared to that observed in the awake or Nembutal-treated rats. In a separate group of saline-infused awake rats, induction of anesthesia with Inactin resulted in a significant increase in hematocrit and a decrease in serum protein concentration. These studies suggest that Inactin anesthesia decreases the ability of the kidney to excrete a saline load and that, in studies of sodium excretion in the rat, especially if volume expansion is to be part of the experimental protocol, Nembutal rather than Inactin may be the anesthetic of choice.These studies were performed while Drs. Knight and Frankfurt were Fellows in Nephrology of Baylor College of Medicine, and were supported in part by a Clinical Investigatorship award to Dr. Weinman and an Associate Investigatorship award to Dr. Frankfurt from the Veterans Administration. This work was presented in part at the Combined Session, Southern Section, American Federation for Clinical Research and the Southern Society for Clinical Investigation, New Orleans, Louisiana, January 27–29, 1977, and has appeared in abstract form in Clin. Res.25, 61 A (1977) 相似文献
8.
Role of peritubular protein concentration in sodium reabsorption 总被引:11,自引:0,他引:11
9.
The purpose of the simulator is to serve as a substitute for human subjects while developing and testing equipment measuring PWV continuously over long periods of time. For this purpose the shape of the simulated pulse should have the geometrical properties of the arterial pulse wave essential for measuring foot to foot PWV. These properties were defined and realized by choosing an appropriate input function and a shaping network. It was proved, by calculations based on steady state analysis, using Laplace transforms, that the simulated arterial pulse wave has the defined geometrical properties. The dicrotic complex, which sometimes interferes with foot to foot PWV measurements, was added to the simulated pulse wave by a separate circuit. 相似文献
10.
Canfield MC; Tamarappoo BK; Moses AM; Verkman AS; Holtzman EJ 《Human molecular genetics》1997,6(11):1865-1871
Congenital nephrogenic diabetes insipidus (NDI) is a rare disease caused
most often by mutations in the vasopressin V2 receptor (AVPR2). We studied
a family which included a female patient with NDI with symptoms dating from
infancy. The patient responded to large doses of desmopressin (dDAVP) which
decreased urine volume from 10 to 4 I/day. Neither the parents nor the
three sisters were polyuric. The patient was found to be a compound
heterozygote for two novel recessive point mutations in the aquaporin-2
(AQP2) gene: L22V in exon 1 and C181W in exon 3. Residue Cys181 in AQP2 is
the site for inhibition of water permeation by mercurial compounds and is
located near to the NPA motif conserved in all aquaporins. Osmotic water
permeability (Pf) in Xenopus oocytes injected with cRNA encoding C181W-AQP2
was not increased over water control, while expression of L22V cRNA
increased the Pf to approximately 60% of that for wild-type AQP2.
Co-injection of the mutant cRNAs with the wild-type cRNA did not affect the
function of the wild-type AQP2. Immunolocalization of AQP2-transfected CHO
cells showed that the C181W mutant had an endoplasmic reticulum-like
intracellular distribution, whereas L22V and wild-type AQP2 showed endosome
and plasma membrane staining. Water permeability assays showed a high Pf in
cells expressing wild-type and L22V AQP2. This study indicates that AQP2
mutations can confer partially responsive NDI.
相似文献