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991.
A solid, acrylic phantom was developed to assess the iodine perceptibility of three digital subtraction angiography (DSA) systems, including one using a recursive filter technique. Three phantoms, designed to mimic flow of iodinated boluses through blood vessels, were used. Each contained four triangular boluses of different widths and of a specific iodine concentration. Motion, required to test recursively filtered DSA systems, was simulated by placing the phantoms on a motorized cart. The phantoms were also used to test flow curve generation in applicable systems. Intersystem differences in perceptibility were attributed to differences in system noise, system resolution, and dynamic range. Flow curves produced with the phantoms were similar to those obtained in patient studies. 相似文献
992.
993.
deVries N; Miller FJ; Wojtowycz MM; Brown PR; Yandow DR; Nelson JA; Kruger RA 《Radiology》1985,157(1):239-241
We have developed a method for acquiring multiple tomographic subtraction images using a rapid, repetitive, circular tomographic motion. The method combines the principles of digital subtraction angiography (DSA) and electronic tomosynthesis. Fifteen patients were examined with the technique using single intravenous bolus injections of contrast material. The image sequence obtained during each injection was first processed with a nontomographic mask subtraction, and the result was then compared with the tomographic DSA scans synthesized from the same sequence. The effective section thickness was approximately 0.5 cm, with each section being 0.5-1.0 cm apart. Twelve of the intravenous DSA scans provided the necessary diagnostic or clinically useful information. Two of the three nondiagnostic scans were caused by avoidable technical reasons. In eight cases, the tomographic DSA scans were superior in quality to the nontomographic scans, exhibited significantly less artifact from patient motion and overlying bowel gas, and were effective in separating overlapping vessels. Tomosynthesis permits multiple electronic imaging of the area of interest without reinjection of contrast material and appears to be more informative than nontomographic intravenous DSA imaging. 相似文献
994.
Long-range mapping of the Philadelphia chromosome by pulsed-field gel electrophoresis 总被引:6,自引:0,他引:6
The Philadelphia chromosome (Ph1) of chronic myelogenous leukemia (CML) contains sequences from chromosome 9, including the ABL protooncogene, that have been translocated to the breakpoint cluster region (bcr) of chromosome 22, giving rise to a bcr-ABL fusion gene, whose product has been implicated in the genesis of CML. Although chromosome 22 translocation breakpoints in CML virtually always occur within the 5.8- kilobase (kb) bcr, chromosome 9 breakpoints have been identified within the known limits of ABL in only a few instances. For a better understanding of the variability of the breakpoints on chromosome 9, we studied the CML cell line BV173. Using pulsed-field gel electrophoresis (PFGE), large-scale maps of the t(9;22) junctions were constructed. The chromosome 9 breakpoint was shown to have occurred within an ABL intron, 160 kb upstream of the v-abl homologous sequences, but still 35 kb downstream of the 5'-most ABL exon. bcr-ABL and ABL-bcr fusion genes were demonstrated on the Ph1 and the 9q+ chromosomes, respectively; both of these genes are expressed. These results suggest that the 9;22 translocation breakpoints in CML consistently occur within the limits of the large ABL gene. RNA splicing, sometimes of very large regions, appears to compensate for the variability in breakpoint location. These studies show that PFGE is a powerful new tool for the analysis of chromosomal translocations in human malignancies. 相似文献
995.
Ben-Ezra J; Burke JS; Swartz WG; Brownell MD; Brynes RK; Hill LR; Nathwani BN; Oken MM; Wolf BC; Woodruff R 《Blood》1989,73(2):579-587
We analyzed specimens from 268 patients with small lymphocytic lymphoma (SL) to identify prognostic factors significant for survival. These patients were staged and treated according to the protocols of the Cancer and Leukemia Group B, Eastern Cooperative Oncology Group, Southeastern Cancer Study Group, and the Southwest Oncology Group. Univariate analysis showed that a large-cell grade greater than I, WBC greater than 10,000/microL, hemoglobin (Hgb) less than 11 g/dL, age greater than or equal to 55 years, and failure to respond to treatment were all poor prognostic factors. Multivariate analysis showed that large-cell grade, age, degree of capsular invasion, and symptom type were independently associated with survival. Separate analyses of cases with and without leukocytosis indicated differences in survival. In patients without leukocytosis, age, presence or absence of anemia, and treatment response were significant prognostic variables; in patients with leukocytosis, large-cell grade, presence or absence of anemia, symptom type, and treatment response were significantly related to survival. Multivariate analysis showed that age was the only significant independent prognostic variable in patients without leukocytosis; in patients with leukocytosis, symptom type, large-cell grade, and bone marrow involvement were independently associated with survival. We conclude that several parameters, both clinical and pathologic, should be assessed at the initial diagnosis of SL to predict prognosis better. 相似文献
996.
Background: This study was conducted to assess the dental treatment requirements of psychiatric patients in comparison with the non psychiatric patients admitted in the hospital. 相似文献
997.
998.
Quigley EM 《Current Treatment Options in Gastroenterology》2000,3(4):273-285
Opinion statement
相似文献
– | Acute pseudo-obstruction may manifest clinically in one of three forms—acute gastroparesis, ileus, and acute colonic pseudo-obstruction (Ogilvie’s syndrome). Though formerly associated primarily with the postoperative state, these entities are increasingly recognized in association with a wide variety of major medical problems. |
– | There are few controlled studies to guide the clinician in the management of these disorders. Treatment remains largely empirical, and time-honored, based primarily on “bowel rest,” nasogastric decompression, and supportive care. While a wide variety of pharmacologic approaches have been advocated, few have been subjected to, or survived, the rigors of a properly controlled trial. Neostigmine is a notable exception, and has been shown to be effective in Ogilvie’s syndrome. |
– | Perforation is a significant threat in megacolon; colonoscopic, or surgical decompression may, therefore, be indicated. Both are associated with significant risks in this context, but may prevent progression to perforation with its attendant mortality. |
– | New approaches seek to exploit current concepts in the pathophysiology of ileus and megacolon but have not, as yet, achieved efficacy in human studies. |
999.
Nuclear translocation of beta-catenin in hereditary and carcinogen- induced intestinal adenomas 总被引:7,自引:4,他引:7
Sheng H; Shao J; Williams CS; Pereira MA; Taketo MM; Oshima M; Reynolds AB; Washington MK; DuBois RN; Beauchamp RD 《Carcinogenesis》1998,19(4):543-549
The physical interaction between beta-catenin and the adenomatous polyposis
coli (APC) gene, and the ability of APC to regulate cytoplasmic levels of
beta-catenin suggest a role for beta-catenin in colorectal carcinogenesis.
In this study, we found that beta-catenin immunoreactivity was detected
exclusively in the cell membrane and cytoplasm of morphologically normal
intestinal epithelial cells with predominant distribution in the
differentiated nonproliferative cell population. In contrast, beta-catenin
was localized predominantly in the nucleus of adenomas from Min/+ mice and
transgenic mice expressing a mutant truncated form of the APC gene
(Apc(delta716) mice). Beta- catenin was expressed predominantly at the cell
membrane and cytoplasm of the nontransformed rat intestinal epithelial
(RIE-1) cells in culture, whereas predominantly nuclear localization of
beta-catenin was observed in the human colon cancer cell line SW480. In the
azoxymethane (AOM) treated rats, overexpression and nuclear localization of
beta- catenin was observed in all adenomas. Previous studies have indicated
the incidence of APC mutations amongst AOM-induced tumors to be 15% or
less. These results demonstrate that nuclear localization of beta- catenin
is a common event in colorectal tumorigenesis.
相似文献
1000.
Tamoxifen is a liver carcinogen in rats and has been shown to increase the
risk of endometrial cancer in women. Recent reports of DNA adducts in
leucocyte and endometrial samples from women treated with tamoxifen
indicate that it may be genotoxic to humans. One of the proposed pathways
for the metabolic activation of tamoxifen involves oxidation to
4-hydroxytamoxifen, which may be further oxidized to an electrophilic
quinone methide. In the present study we show that 4- hydroxytamoxifen
quinone methide reacts with DNA to form covalent adducts. The major
products, which result from 1,8-addition of the exocyclic nitrogen of
deoxyguanosine to the conjugated system of 4- hydroxytamoxifen quinone
methide, are characterized as (E)- and (Z)-
alpha-(deoxyguanosin-N2-yl)-4-hydroxytamoxifen.
相似文献