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91.
92.
Gudowska I Sobolevsky N Andreo P Belkić D Brahme A 《Physics in medicine and biology》2004,49(10):1933-1958
The development of the Monte Carlo code SHIELD-HIT (heavy ion transport) for the simulation of the transport of protons and heavier ions in tissue-like media is described. The code SHIELD-HIT, a spin-off of SHIELD (available as RSICC CCC-667), extends the transport of hadron cascades from standard targets to that of ions in arbitrary tissue-like materials, taking into account ionization energy-loss straggling and multiple Coulomb scattering effects. The consistency of the results obtained with SHIELD-HIT has been verified against experimental data and other existing Monte Carlo codes (PTRAN, PETRA), as well as with deterministic models for ion transport, comparing depth distributions of energy deposition by protons, 12C and 20Ne ions impinging on water. The SHIELD-HIT code yields distributions consistent with a proper treatment of nuclear inelastic collisions. Energy depositions up to and well beyond the Bragg peak due to nuclear fragmentations are well predicted. Satisfactory agreement is also found with experimental determinations of the number of fragments of a given type, as a function of depth in water, produced by 12C and 14N ions of 670 MeV u(-1), although less favourable agreement is observed for heavier projectiles such as 16O ions of the same energy. The calculated neutron spectra differential in energy and angle produced in a mimic of a Martian rock by irradiation with 12C ions of 290 MeV u(-1) also shows good agreement with experimental data. It is concluded that a careful analysis of stopping power data for different tissues is necessary for radiation therapy applications, since an incorrect estimation of the position of the Bragg peak might lead to a significant deviation from the prescribed dose in small target volumes. The results presented in this study indicate the usefulness of the SHIELD-HIT code for Monte Carlo simulations in the field of light ion radiation therapy. 相似文献
93.
Isolation of human immunodeficiency virus (HIV) from plasma during primary HIV infection 总被引:13,自引:0,他引:13
Jan Albert Hans Gaines Anders Snnerborg Gunnel Nystrm Pehr Olov Pehrson Francesca Chiodi Madeleine von Sydow Lars Moberg Knut Lidman Bertil Christensson Birgitta sj Eva Maria Feny 《Journal of medical virology》1987,23(1):67-73
Human immunodeficiency virus (HIV) has been isolated from plasma in 6 of 7 patients showing clinical symptoms of a primary HIV infection. Parallel cultures from peripheral blood mononuclear cells (PBMC) yielded virus in 5 patients. In one case, virus could only be isolated from the cerebrospinal fluid but not from peripheral blood. Detectable viremia was transient and preceded the appearance of HIV specific antibodies. After cessation of acute symptoms, the frequency of HIV isolations was similar to that of asymptomatic carriers (23 and 26%, respectively). The role of the immune response in terminating detectable viremia remains to be established. 相似文献
94.
Dahle MK Øverland G Myhre AE Stuestøl JF Hartung T Krohn CD Mathiesen Ø Wang JE Aasen AO 《Infection and immunity》2004,72(10):5704-5711
Sepsis caused by gram-positive bacteria lacking lipopolysaccharide (LPS) has become a major and increasing cause of mortality in intensive-care units. We have recently demonstrated that the gram-positive-specific bacterial cell wall component lipoteichoic acid (LTA) stimulates the release of the proinflammatory cytokines in Kupffer cells in culture. In the present study, we have started to assess the signal transduction events by which LTA induces the production of tumor necrosis factor alpha (TNF-alpha), interleukin-6 (IL-6), and the anti-inflammatory cytokine IL-10 in rat Kupffer cells. LTA was found to trigger phosphorylation of mitogen-activated protein kinases (MAPK) (p38 MAPK and ERK 1/2) and protein kinase B (PKB). Compared to LPS, LTA was more potent in inducing PKB phosphorylation after 40 min, although we found that the cytokine responses were similar. For both bacterial molecules, blocking phosphatidylinositol 3-kinase (PI3-K; Ly294002) or Janus kinase 2 (JAK-2; AG490) particularly affected the induction of IL-6 and IL-10 release, whereas TNF-alpha levels were strongly reduced by inhibition of Src family tyrosine kinases (PP2). All three cytokines were reduced by inhibition of p38 MAPK (SB202190) or the broad-range tyrosine kinase inhibitor genistein, whereas IL-6 release was particularly blocked by inhibition of ERK 1/2 (PD98059). Divergences in the regulatory pathways controlling TNF-alpha, IL-10, and IL-6 production in Kupffer cells following LPS or LTA stimulation may create a basis for understanding how the balance between pro- and anti-inflammatory cytokines is regulated in the liver following infections by gram-positive or gram-negative bacteria. 相似文献
95.
Lingwei?Wang Sten?Eirik?W?Jacobsen Anders?Bengtsson David?ErlingeEmail author 《BMC immunology》2004,5(1):16
Background
Extracellular nucleotides (ATP, ADP, UTP and UDP) exert a wide range of biological effects in blood cells mediated by multiple ionotropic P2X receptors and G protein-coupled P2Y receptors. Although pharmacological experiments have suggested the presence of several P2 receptor subtypes on monocytes and lymphocytes, some results are contradictory. Few physiological functions have been firmly established to a specific receptor subtype, partly because of a lack of truly selective agonists and antagonists. This stimulated us to investigate the expression of P2X and P2Y receptors in human lymphocytes and monocytes with a newly established quantitative mRNA assay for P2 receptors. In addition, we describe for the first time the expression of P2 receptors in CD34+ stem and progenitor cells implicating a potential role of P2 receptors in hematopoietic lineage and progenitor/stem cell function. 相似文献96.
The ring-infected erythrocyte surface antigen of Plasmodium falciparum associates with spectrin in the erythrocyte membrane. 总被引:7,自引:0,他引:7
The malaria parasite Plasmodium falciparum synthesises a protein, RESA, which associates with the membrane of newly invaded erythrocytes. Using spent supernatants from P. falciparum growing in culture as a source of soluble RESA we have developed an assay to examine the characteristics of RESA binding to the erythrocyte membrane in vitro. RESA associated with the Triton X-100 insoluble proteins on the inner face of the host erythrocyte membrane but did not bind to the outer surface of intact erythrocytes. Other proteins present in culture supernatants did not bind to the erythrocyte membrane. RESA was co-sedimented with the ternary complex formed between actin, spectrin and band 4.1 and co-precipitated with spectrin precipitated with anti-spectrin antibodies. The extent of association between RESA and the inner face of the erythrocyte membrane was reduced by the inclusion of excess purified spectrin in the assay. Thus, RESA appears to be associated with spectrin in the erythrocyte membrane skeleton. 相似文献
97.
Lymphomatoid granulomatosis and malignant lymphoma of the central nervous system in the acquired immunodeficiency syndrome 总被引:2,自引:0,他引:2
While primary and secondary malignant lymphomas have been well-documented in the CNS of patients with the acquired immunodeficiency syndrome (AIDS), only one case of lymphomatoid granulomatosis (LG) involving the CNS has been reported. We present three AIDS patients with multiple grossly evident foci of necrosis in the cerebral hemispheres which, on histologic evaluation, were seen to contain angiocentric mixed chronic inflammatory infiltrates with atypical mononuclear cells, luminal thrombosis, and infarction, which is typical of LG. LG was also identified in sections of the lung in one case. Lymphoma was found in other regions of the brain in two cases, suggesting the evolution of LG into cerebral lymphoma. In addition, widespread perivascular multinucleate syncytial giant cells, associated with human immunodeficiency virus (HIV) infection of the CNS, were identified in all patients. The features of LG, its relationship to lymphoma, and the possible etiologic role of an immunodeficiency state or the HIV virus in the pathogenesis of LG are discussed. 相似文献
98.
Monospecific polyclonal antisera were prepared against the 129-kDa, early, single-strand DNA-binding protein (DB129) of strain Colburn cytomegalovirus (CMV), and used to study its distribution in infected cells and its relatedness to a proposed human CMV (HCMV) counterpart (DB140). Indirect immunofluorescence of fixed, infected human fibroblasts showed DB129 to be localized within the intranuclear inclusions characteristic of replicating CMV. Treatment of infected cells with 50 to 100 micrograms phosphonoformic acid per milliliter resulted in the overproduction of DB129 and its accumulation within nuclei, both inside the inclusions and in surrounding areas of the nucleoplasm, whereas treatment with 500 micrograms/ml prevented inclusion formation, and DB129 was localized at discrete points throughout the infected-cell nuclei. The sera cross-reacted an estimated 10% with HCMV DB140 in an indirect immunoassay, and their use in immunofluorescence localized DB140 to the nuclear inclusions of HCMV-infected cells. Their immunological cross-reactivity, as well as their similar biochemical properties and intracellular distribution, support the likelihood that DB129 and DB140 are the protein products of homologous genes. The relationship of these proteins to the herpes simplex major DNA-binding protein is discussed. 相似文献
99.
HLA-A,B,C and DR antigens in psoriasis 总被引:3,自引:0,他引:3
51 psoriasis vulgaris patients and 93 controls were tested for HLA-A,B,C and DR antigenic frequencies. Significant increases of B17, Cw6 and DR7 were documented in the patient group, as well as a decreased frequency of DR1. The significance of these findings is discussed. DR7 occurred more often together with Cw6 in psoriasis patients than in controls, which might suggest that there are at least two interacting HLA linked genes which increase the disease susceptibility and possibly one DR1 linked gene associated with resistence to the disease. 相似文献
100.
Pia Bjrck Carina Elenstrm-Magnusson Anders Rosn Eva Severinson Staffan Paulie 《European journal of immunology》1993,23(8):1771-1775
We have previously found that interleukin-4 and CD40 monoclonal antibodies (mAb) are strong potentiatiors of homotypic B cell aggregation which is dependent on LFA-1. We show here that CD23 mAb were also able to inhibit aggregation to a similar extent as LFA-1 antibodies. This inhibition was restricted to the MHM6 epitope of CD23 and antibodies to other epitopes [Epstein-Barr virus (EBV) CS-1, EBV CS-2, EBV CS-5 and mAb 25] or occupation of the Fc-binding site by IgE had no or a slightly enhancing effect on aggregation. When testing two antibodies to CD21, the recently defined ligand for CD23, one of these (BU32) was found to be inhibitory whereas the other (THB5) had no effect. By combining antibodies to LFA-1 and CD23, aggregation was often completely inhibited. These data suggest that LFA-1/ICAM-1 and CD23/CD21 are the major molecules involved in homotypic aggregation of human B cells. 相似文献