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61.
The goal of IMRT is to achieve an isodose distribution conformed to the tumor while avoiding the organs at risk. For these tasks several gantry angles are selected, each one containing a series of different leaf configurations for the multileaf collimator (MLC) (segments). Verifying the relative distributions as well as the absolute doses is an important step for quality assurance issues. We have observed that an accurate modeling of the transmission of the primary x-ray fluence through the jaws and MLC as well as the head scatter is crucial for a precise calculation of relative doses and monitor units. Also, an inaccurate calculation of the output factor for small size segments can lead to important differences in the absolute dose for points under these segments. Incorrect models could lead to systematic errors of around 5% to 10% in the calculated monitor units and a shift in the isodose curves. 相似文献
62.
Redefining the significance of aneuploidy in the prognostic assessment of colorectal cancer 总被引:5,自引:0,他引:5
Risques RA Moreno V Marcuello E Petriz J Cancelas JA Sancho FJ Torregrosa A Capella G Peinado MA 《Laboratory investigation; a journal of technical methods and pathology》2001,81(3):307-315
The aberrant content of DNA, or aneuploidy, is a hallmark of tumor cells and may be associated with malignant potential. Based on the hypothesis that aneuploidy, as a form of genetic instability, results in an increased capability to generate cell heterogeneity, we investigated whether a comprehensive assessment of aneuploidy extent and degree might be a reliable indicator of tumor aggressiveness. DNA content was determined by flow cytometry in the infiltrating front of 131 paraffin-embedded primary colorectal carcinomas collected in a prospective design. Enrichment of tumor cells by sample microdissection resulted in neoplastic cell contents above 75%. An estimate of aneuploidy, the aneuploidy index (AI), was calculated as the tumor DNA content adjusted by the percentage of diploid and aneuploid cells in G0/G1. Thirty-nine tumors were diploid, 90 hyperdiploid, and 2 hypodiploid. The mean AI in aneuploid tumors was 1.20+/-0.17 and correlated with Dukes' stage and metastasis (p < 0.05). A high AI (receiver operating characteristic curve cutoff value greater than 1.14) predicted a poorer outcome in univariate (p = 0.004) and multivariate (p = 0.01) analyses. Based on these results, we postulate that aneuploidy is the molecular engine of progression in a subset of colorectal cancers, in which the AI seems to be a sensible and independent gauge of malignant potential. The AI determination may have prognostic application in colorectal cancer, especially in low-grade tumors, which might benefit from coadjuvant therapies. 相似文献
63.
Severe, late-onset graft-versus-host disease in a liver transplant recipient documented by chimerism analysis 总被引:4,自引:0,他引:4
Pollack MS Speeg KV Callander NS Freytes CO Espinoza AA Esterl RM Abrahamian GA Washburn WK Halff GA 《Human immunology》2005,66(1):28-31
A 52-year-old liver transplant recipient presented 8 months after transplantation with oral thrush, then 3 days later with oral ulcers and a diffuse rash, and 5 days later with an acutely reduced white blood cell count, rash, fever, and diarrhea. Bone marrow biopsy revealed severe aplasia. Although graft-versus-host disease (GVHD) was considered, the late onset of these symptoms was felt to render this etiology unlikely because GVHD usually occurs 2 to 6 weeks after transplantation. All potentially myelosuppressive medications were discontinued, and the patient was treated with high doses of hematopoietic growth factors. Because his symptoms continued, chimerism analysis was performed, which indicated that 96% of the peripheral blood mononuclear cells were of liver-donor origin. Ultimately, the patient underwent an allogeneic peripheral blood hematopoietic progenitor cell transplant from a human leukocyte antigen-identical brother, but he died 5 days after transplantation of overwhelming Candida kruseii infection. To our knowledge, this is the first chimerism-analysis-documented case of severe acute GVHD presenting so late after liver transplantation. It is of note that the patient had no known risks for GVHD in that he was relatively young and shared only one major human leukocyte antigen with his donor. Consideration should be given to GVHD as a cause of bone marrow aplasia at any time after organ transplantation. Storage of cell pellets from all transplant recipients and donors is highly recommended to facilitate the diagnostic evaluation. 相似文献
64.
Moreno Sabater A Moreno M Moreno FJ Eguiluz C van Rooijen N Benito A 《Parasitology research》2005,95(2):97-105
The main objective of this study was to determine whether a chemical immunomodulation protocol could reduce the resistance of NOD/LtSz-SCID mice to Plasmodium falciparum infection and provide an improved mouse model for screening the antimalarial activity of new compounds. This model was compared with the presently used immunodeficient Beige/Nude/Xid (BNX) mouse model, using the same protocol, in terms of percentage of infected mice, parasite development, leukocyte response and phagocytosis of P. falciparum infected cells in various organs. Our results show that the combination of the chemical immune modulation protocol with the genetic background of NOD/LtSz-SCID mice results in the development of long-lasting P. falciparum infection in a high percentage of mice. A comparison of the results obtained in the histological study for both mouse models suggests that the higher rate of success in NOD/LtSz-SCID mice could be related to the reduced macrophage recruitment developed in different tissues to remove the parasite from blood. 相似文献
65.
Reza-Albarran AA Gomez-Perez FJ Lopez JC Herrera M Gamboa-Dominguez A Keirns C Aranda A Rull JA 《Endocrine pathology》1999,10(3):251-257
Pigmented nodular cortical hyperplasia, a rare cause of Cushing’s syndrome, is characterized by resistance to inhibition with
dexamethasone and normal sized adrenal glands with multiple, small pigmented nodules. The disorder may be a component of a
syndrome inherited as an autosomal dominant pattern that includes intra- and extracardiac myxomas, lentiginous lesions, blue
nevi, other functional endocrine tumors, and peripheral nerve tumors (Carney’s complex).
We report a patient in whom bilateral myelolipomas were found, in addition to the usual features of this complex. A 29-yr-old
man was admitted to the hospital for Cushing’s syndrome of probably more than 15 yr duration. Physical examination showed
diffuse facial hyperchromatic macules, 0.2–0.5 cm, predominantly around the lips and on the palmar surfaces of the fingers.
Results with dexamethasone suppression nocturnal testing (1 and 8 mg) were compatible with an adrenal adenoma. The computed
tomography (CT) of the sella turcica was normal. Adrenal CT showed a tumor in the left gland with a double component: one
solid and another suggestive of fat, consistent with an angiomyelolipoma. Following 5 wk treatment with ketoconazole, 800
mg per day po, serum cortisol decreased to 5.9 μg/dL, morning and evening, respectively.
Bilateral adrenalectomy was performed. Pathologic examination revealed pigmented nodular cortical hypersplasia and a dominant
myelolipoma in the left adrenal. A microscopic myelolipoma was identified in the right adrenal.
An echocardiogram showed a mass on the posterior wall of the left ventricle which was a myxoma. Study of the patient's family
disclosed two sisters with facial lentigines. Echocardiograms were performed on all available first degree relatives: all
were normal. Nocturnal inhibition with dexamethasone revealed that one of the patient’s sisters with lentigines also had hypercortisolism.
Myelolipoma has been reported in association to Cushing syndrome in humans and experimentally after pituitary extracts in
animals. The relationship between this finding and the Carney’s complex remain elusive. 相似文献
66.
Involvement of clusterin and the aggresome in abnormal protein deposits in myofibrillar myopathies and inclusion body myositis 总被引:2,自引:0,他引:2
Ferrer I Carmona M Blanco R Moreno D Torrejón-Escribano B Olivé M 《Brain pathology (Zurich, Switzerland)》2005,15(2):101-108
Myofibrillar myopathies (MM) are characterized morphologically by the presence of non-hyaline structures corresponding to foci of dissolution of myofibrils, and hyaline lesions composed of aggregates of compacted and degraded myofibrillar elements. Inclusion body myositis (IBM) is characterized by the presence of rimmed vacuoles, eosinophilic inclusions in the cytoplasm, rare intranuclear inclusions, and by the accumulation of several abnormal proteins. Recent studies have demonstrated impaired proteasomal expression and activity in MM and IBM, thus accounting, in part, for the abnormal protein accumulation in these diseases. The present study examines other factors involved in protein aggregation in MM and IBM. Clusterin is a multiple-function protein which participates in Abeta-amyloid, PrP(res) and a-synuclein aggregation in Alzheimer disease, prionopathies and a-synucleinopathies, respectively. gamma-Tubulin is present in the centrosome and is an intracellular marker of the aggresome. Moderate or strong clusterin immunoreactivity has been found in association with abnormal protein deposits, as revealed by immunohistochemistry, single and double-labeling immunofluorescence and confocal microscopy, in MM and IBM, and in target structures in denervation atrophy. Gamma-Tubulin has also been observed in association with abnormal protein deposits in MM, IBM, and in target fibers in denervation atrophy. These morphological findings are accompanied by increased expression of clusterin and gamma-tubulin in muscle homogenates of MM and IBM cases, as revealed by gel electrophoresis and Western blots. Together, these observations demonstrate involvement of clusterin in protein aggregates, and increased expression of aggresome markers in association with abnormal protein inclusions in MM and IBM and in targets, as crucial events related to the pathogenesis of abnormal protein accumulation and degradation in these muscular diseases. 相似文献
67.
The outer membranes of Brucella spp. are resistant to bactericidal cationic peptides. 总被引:4,自引:1,他引:4 下载免费PDF全文
The actions of polymyxin B, rabbit polymorphonuclear lysosome extracts, 14 polycationic peptides (including defensin NP-2, cecropin P1, lactoferricin B, and active peptides from cationic protein 18 and bactenecin), EDTA, and Tris on Brucella spp. were studied, with other gram-negative bacteria as controls. Brucella spp. were comparatively resistant to all of the agents listed above and bound less polymyxin B, and their outer membranes (OMs) were neither morphologically altered nor permeabilized to lysozyme by polymyxin B concentrations, although both effects were observed for controls. EDTA and peptides increased or accelerated the partition of the hydrophobic probe N-phenyl-naphthylamine into Escherichia coli and Haemophilus influenzae OMs but had no effect on Brucella OMs. Since Brucella and H. influenzae OMs are permeable to hydrophobic compounds (G. Martínez de Tejada and I. Moriyón, J. Bacteriol. 175:5273-5275, 1993), the results show that such unusual permeability is not necessarily related to resistance to polycations. Although rough (R) B. abortus and B. ovis were more resistant than the controls were, there were qualitative and quantitative differences with smooth (S) brucellae; this may explain known host range and virulence differences. Brucella S-lipopolysaccharides (LPSs) had reduced affinities for polycations, and insertion of Brucella and Salmonella montevideo S-LPSs into the OM of a Brucella R-LPS mutant increased and decreased, respectively, its resistance to cationic peptides. The results show that the core lipid A of Brucella LPS plays a major role in polycation resistance and that O-chain density also contributes significantly. It is proposed that the features described above contribute to Brucella resistance to the oxygen-independent systems of phagocytes. 相似文献
68.
Decrease of IgE-dependent platelet activation in Hymenoptera hypersensitivity after specific rush desensitization. 总被引:1,自引:1,他引:1 下载免费PDF全文
A Tsicopoulos A B Tonnel B Wallaert M Joseph J C Ameisen P Ramon J P Dessaint A Capron 《Clinical and experimental immunology》1988,71(3):433-438
A receptor for the Fc fragment of IgE on human platelets has been recently described, which mediated an IgE-dependent activation in the presence of specific allergen. We investigated the allergen-induced activation of platelets from patients with Hymenoptera hypersensitivity before and after specific rush desensitization. Nineteen patients with a history of anaphylactic reactions were included (15 sensitive to yellow-jacket and four to honey-bee venom), fourteen/nineteen having experienced severe life-threatening systemic reactions and 5/19 large local reactions. All showed positive skin tests and high values of specific IgE. By comparison to the baseline results obtained before desensitization, a significant decrease of platelet activation (76.8% inhibition) after rush desensitization was observed. In the case of two polysensitized patients, after Hymenoptera venom desensitization alone, platelets not only lost their reactivity to venom but also towards the other allergen. This modulation of the IgE-dependent platelet reactivity during desensitization offers therefore a new approach for the study of allergen-induced desensitization. 相似文献
69.
Voltage clamp experiments were carried out on sheep Purkinje fibers to determine the effect of Ach on the time-dependent currents.On the pacemaker current (i
K
2) Ach 10–6 mol·l–1 had the following effects: shift of the activation curve by a few mV in the depolarizing direction, without change in the rectifier ratio. The potential dependence of the time constants for activation and deactivation was influenced in a similar way as the activation curve.Ach had no effect on the positive dynamic current (i
qr
) or the late plateau outward current (i
x
).The slow inward current (i
si
) as well as the transient inward current (T.I.) were reduced in amplitude and slowed in time course by Ach.The changes in pacemaker current are important in explaining the increased rate of diastolic depolarization in the presence of Ach. The decrease of slow inward current by Ach cannot be made responsible for the plateau shift or the prolongation of the action potential.Supported by F.G.W.O. Belgium 3.0087.74 相似文献
70.
Ramon C Schimpf P Wang Y Haueisen J Ishimaru A 《Physics in medicine and biology》2002,47(7):1167-1184
Changes in anterior and posterior body surface potential maps (BSPMs) due to myocardial anisotropy were examined using a highly heterogeneous finite element model of an adult male subject constructed from segmented magnetic resonance images. A total of 23 different tissue types were identified in the whole torso. The myocardial fibre orientations in the human heart wall were mapped from the fibre orientations of a canine heart which are available in the literature using deformable mapping techniques. The current and potential distributions in the whole torso were computed using dipolar sources in the septum, apical area, left ventricular wall or right ventricular wall. For each dipole x, y, z orientations were studied. An adaptive finite element solver was used to compute currents and potential distributions in the whole torso with an element size of 0.78 x 0.78 x 3 mm in the myocardium and larger elements in other parts of the torso. For each dipole position two cases were studied. In one case the myocardium was isotropic and in the other it was anisotropic. It was found that BSPMs showed a very notable difference between the isotropic and the anisotropic myocardium for all dipole positions with the largest difference for the apical dipoles. The correlation coefficients for the BSPMs between the isotropic and anisotropic cases ranged from 0.83 for an apical dipole to 0.99 for an RV wall dipole. These results suggest that myocardial fibre anisotropy plays an important role in determining the body surface potentials. 相似文献