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排序方式: 共有750条查询结果,搜索用时 31 毫秒
81.
In vivo behavior of human radioiodinated antithrombin III: distribution among three physiologic pools 总被引:3,自引:0,他引:3
It has recently been shown that antithrombin III (AT) distributes between plasma, a noncirculating vascular-associated pool and an extravascular pool in rabbit. Study of the in vivo behavior of autologous human 131I-AT demonstrates that in humans AT also distributes among three pools that are analogous to those found in rabbit. From the in vivo kinetic behavior of the 131I-labeled AT, the fractions of total-body AT in the plasma, noncirculating vascular- associated, and extravascular pools were calculated to be 0.393 +/- 0.015, 0.109 +/- 0.016, and 0.496 +/- 0.014, respectively. From three- exponential plasma radioactivity disappearance curves, an average plasma fractional catabolic rate, j3, of 0.576 +/- 0.034 day-1 was obtained for five healthy young men. This is almost identical to the result obtained if plasma 131I-AT disappearance is assumed to fit a two- exponential curve (0.546 +/- 0.038), where the constant C2 from *Ap(t) = C1e-a1t + C2e-a2t is assumed to be equal to 1 - C1. The fraction of the total vascular AT catabolized daily, j3.5, was calculated to be 0.457 +/- 0.034, and the fractional catabolic rate of total-body AT, jT, averaged 0.2271 +/- 0.0176. The results give further support to a model of in vivo behavior in which the vascular AT distributes between plasma and an endothelial receptor. Thus, the latter may serve to mediate activation of AT for its reaction with coagulation proteases and to mediate its entrance into the endothelial cell, where it is either transported to the extravascular fluids or is catabolized. 相似文献
82.
We have previously reported the isolation of a monoclonal antibody (NHL- 30.5) that reacts with an antigen expressed on a substantial proportion of marrow and blood cells of most patients with newly diagnosed or relapsing acute myeloid leukemia. This antigen is also found on several cell lines derived from myeloid malignancies of human origin. It is not present on mature hemopoietic cells or on the majority of differentiating bone marrow cells. In order to determine whether the NHL-30.5 antigen may, nevertheless, be expressed on low-frequency primitive normal hemopoietic cells, not detected in standard antibody screening procedures, its expression was studied on clonogenic erythropoietic and granulopoietic cells. Light-density (less than 1.077 g/mL) suspensions of normal or chronic myelogenous leukemia bone marrow and peripheral blood cells were stained with NHL-30.5 and fluorescein isothiocyanate labeled second antibody and then sorted into two fractions using the fluorescence-activated cell sorter. The first contained the top 5% of cells with the highest fluorescence intensity. The remainder were collected in the second fraction. Colony assays of both fractions showed the first to be enriched in CFU-E, BFU-E, and CFU- C content (fourfold to 17-fold). The second fraction was correspondingly depleted of these progenitors. These findings reveal NHL-30.5 antigen expression to be a transient event during normal hemopoiesis that characterizes primitive hemopoietic cells on several pathways. Subsequent experiments showed that the presence of up to 10 micrograms/mL of purified NHL-30.5 antibody in colony assay cultures neither inhibited nor stimulated colony formation. Marrow fibroblasts (subcultured marrow adherent cells) were NHL-30.5 negative. Immunoprecipitation studies showed that the antigen detected by NHL- 30.5 is clearly distinct from that identified by My-10, another monoclonal antibody that has previously shown some similarities to NHL- 30.5. It thus appears that the NHL-30.5 antibody reacts with a new myeloid differentiation antigen of as yet unidentified function that is normally restricted in its expression to early stages of hemopoiesis. 相似文献
83.
BACKGROUND: Cyclooxygenase (COX) is the rate-limiting enzyme in the synthesis of prostaglandins. It exists in two isoforms: COX-1 which is constitutively expressed and COX-2 which is an inducible form activated by a variety of cytokines during inflammation. DISCUSSION: Interest in this enzyme arose in the early 1990s when, following epidemiological studies, aspirin (which is a COX inhibitor) was found to reduce the risk of colorectal cancer. Since then various studies to decipher the mechanisms by which COX reduces the development of colorectal cancer have been undertaken. One of the mechanisms being studied is its role in the angiogenesis of colorectal cancer. Angiogenesis of its own has been well established as a key factor in the development of tumours. Agents that specifically inhibit COX-2 are now in clinical development and have been licensed to be used in patients with familial adenomatosis polyposis. CONCLUSION: What needs to be determined is whether the antiangiogenic effects of COX-2 inhibitors can be used in the prevention and/or treatment of colorectal cancer and its metastases. 相似文献
84.
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86.
Jansen PM; Pixley RA; Brouwer M; de Jong IW; Chang AC; Hack CE; Taylor FB Jr; Colman RW 《Blood》1996,87(6):2337-2344
In previous studies, we have shown that administration of monoclonal antibody (MoAb) C6B7 against human factor XII to baboons challenged with a lethal dose of Escherichia coli abrogates activation of the contact system and modulates secondary hypotension. To evaluate the contribution of activated contact proteases to the appearance of other inflammatory mediators in this experimental model of sepsis, we studied the effect of administration of MoAb C6B7 on activation of complement and fibrinolytic cascades, stimulation of neutrophil degranulation, and release of the proinflammatory cytokines, tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6). Activation of the complement system, as reflected by circulating C3b/c and C4b/c levels, was significantly reduced in five animals that had received MoAb C6B7 before a lethal dose of E coli as compared with five control animals that had been given a lethal challenge only. Inhibition of contact activation also modulated the fibrinolytic response, since the release of tissue-type plasminogen activator (t-PA) and the appearance of plasmin-alpha2-antiplasmin (PAP) complexes into the circulation was significantly attenuated upon pretreatment with anti-factor XII MoAb. In contrast, plasma levels of plasminogen activator inhibitor (PAI) were modestly enhanced in the treatment group. Degranulation of neutrophils, as assessed by circulating elastase-alpha1-protease inhibitor complexes, and release of IL-6 but not of TNF-alpha was decreased in anti-factor XII-treated animals. Observed differences in the inflammatory response between treatment and control groups were not likely due to different challenges, since the number of E coli that had been infused, as well as circulating levels of endotoxin after the challenge, were similar for both groups. These data suggest that activation of the contact system modulates directly or indirectly various mediator systems involved in the inflammatory response during severe sepsis in nonhuman primates. 相似文献
87.
Pecorara M; Casarino L; Mori PG; Morfini M; Mancuso G; Scrivano AM; Boeri E; Molinari AC; De Biasi R; Ciavarella N 《Blood》1987,70(2):531-535
In this study, we used DNA polymorphisms for carrier detection and prenatal diagnosis of hemophilia A in a large group of Italian families. The restriction fragment length polymorphisms (RFLPs) investigated were the intragenic polymorphic Bc/I site within the factor VIII gene; the extragenic multiallelic Taq I system at the St14 locus; and the extragenic Bg/II site at the DX13 locus. The factor VIII probe was informative in 30%, St14 in 82%, and DX13 in 60% of obligate carriers. The combination of factor VIII-Bc/I and St14-Taq I showed that 91% of obligate carriers were heterozygotes for one or both; with all three probes, only 4% of obligate carriers were noninformative. In families clearly segregating for hemophilia A, RFLP analysis allowed us to define the carrier status for the hemophilia A gene in all 27 women tested. RFLP analysis allowed us to exclude the carrier status in 39 of 45 female relatives of sporadic patients. The combination of RFLP analysis and biological assay of factor VIII allowed us to identify a de novo mutation in the maternal grandfather in 7 of 12 of the families with sporadic cases, for which members of three generations were available for study. Nine of 10 couples requesting prenatal diagnosis provided informative RFLP DNA pattern. Carrier status was excluded in two women, two fetuses were shown to be female, and prenatal diagnosis was carried out in five pregnancies by DNA analysis. Prenatal testing was successful in three instances and failed in two because a sufficient amount of chorionic villous DNA was not obtained for the analysis. 相似文献
88.
Nonhomogeneous distribution of leukemia in the bone marrow during minimal residual disease 总被引:2,自引:0,他引:2
In a rat model (BNML) for human acute myelocytic leukemia the distribution of leukemic cells in bone marrow samples from various sites was investigated, using monoclonal antibodies (MoAbs) and flow cytometry. Rats were studied before chemotherapy as well as thereafter, ie, in the "minimal residual disease" (MRD) phase. Bone marrow from different types of bones was analyzed from each animal. Before treatment, the ratio of the measured extreme values (ie, highest/lowest value) for leukemic cell frequencies in bones from individual rats ranged from 3.7 to 11.7. During the MRD phase the ratios of the extremes ranged from a factor of 36 to more than 13,000 from one rat to another. The variability between bones of comparable size was estimated by studying the ribs from each individual animal. Within individuals the extremes differed by a factor of 1.2 to 4.0 before chemotherapy and from 2.4 to greater than 320 after chemotherapy. The variability within the marrow cavity of a single bone was determined by analyzing multiple samples from femoral bones cut into slices. The leukemic cell frequency appeared to vary considerably, ie, before treatment from 1.7 to 7.3 and during MRD from 4 to 28,000. The presented data may contribute to understanding the sometimes conflicting observations in leukemic patients. Improvement of methods for detecting MRD will not automatically lead to a more accurate estimation of the total tumor burden. The reliability of diagnoses based on the analysis of single bone marrow aspirates appears to be highly questionable. 相似文献
89.
RG Lee K Nakamura AC Tsamandas K Abu-Elmagd H Furukawa WR Hutson J Reyes JS Tabasco-Minguillan S Todo AJ Demetris 《Gastroenterology》1996,110(6):1820-1834
BACKGROUND & AIMS: Intestinal transplantation is a developing therapeutic option for patients with irreversible intestinal failure or short bowel syndrome. The aim of this study was to delineate the histopathology of human intestinal allografts and to define the features of intestinal rejection. METHODS: The histological features of 3015 endoscopic biopsy specimens and 23 allograft specimens from 62 intestinal recipients were analyzed retrospectively and correlated with clinical findings. RESULTS: Acute allograft rejection was characterized by a varying combination of crypt injury, mucosal infiltration primarily by mononuclear cells (including blastic lymphocytes), and increased crypt cell apoptosis (more than 2 per 10 crypts). It represented a patchy, often ileal-centered process that could progress to mucosal ulceration; later episodes (more than 100 days posttransplant) tended to show lesser cellular infiltration and greater apoptosis than earlier episodes. Correlation with clinical rejection was good (false-positive rate of 9%; false-negative rate of 26%). Two resected specimens showed obliterative arteriopathy indicative of chronic rejection. In other specimens, preservation injury, cytomegalovirus infection, post-transplant lymphoproliferative disorder, and nonspecific features of active or past mucosal injury could be recognized. CONCLUSIONS: Mucosal biopsy specimens are a useful means of monitoring intestinal allografts. Based on features validated by clinical correlation, acute rejection can be identified reliably and can be differentiated from the other pathological processes affecting the intestinal allograft. (Gastroenterology 1996 Jun;110(6):1820-34) 相似文献
90.
AC Chambers AV Patil R Alves JC Hopkins J Armstrong RN Lawrence 《Annals of the Royal College of Surgeons of England》2012,94(8):548-551