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  • 1
    ISSN: 1572-9540
    Keywords: muon-catalyzed fusion ; deuterium ; solid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Muon-catalyzed fusion in deuterium has traditionally been studied in gaseous and liquid targets. The TRIUMF solid hydrogen layer target system has been used to study the fusion reaction rates in the solid phase at a target temperature of 3 K. Both branches of the cycle were observed; neutrons by a liquid organic scintillator, and protons by a silicon detector located inside the target system. The effective molecular formation rate from the upper hyperfine state and the spin exchange rate have been measured, and information on the branching ratio parameters has been extracted.
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  • 2
    ISSN: 1572-9540
    Keywords: muon-catalyzed fusion ; thickness measurement ; solid hydrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In experiments using the TRIUMF solid hydrogen target system, the knowledge of the target thickness and uniformity is often essential in order to extract physical parameters from the data. We have characterized the thickness and uniformity of frozen targets using the energy loss of alpha particles. An accuracy of ∼5% was achieved, a limit imposed by the uncertainty in the stopping powers: The details of the method are described, and the thickness calibration of the target is presented.
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  • 3
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The knowledge of muon transfer from protium to tritium is essentially theoretical and the different theoretical values disagree partially. Using solid hydrogen-tritium targets, with different tritium concentrations, we obtained precise experimental results for the transfer rate to tritium and the ppµ molecular formation rate. The time spectra of neutrons and alpha particles produced after dtµ fusion are used to determine the transfer rate λpt and the molecule formation rate λppµ.
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  • 4
    ISSN: 1572-9540
    Keywords: muon catalyzed fusion ; sticking ; stripping ; multilayer film
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We propose a direct measurement of muon sticking to alpha particles in muon-catalyzed dt fusion at a high density. Exploiting the features of a multilayer thin-film target developed at TRIUMF, the sticking is determined directly by detection of charged fusion products. Experimental separation of initial sticking and stripping may become possible for the first time. Monte Carlo simulations, as well as preliminary results of test measurements are described.
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  • 5
    ISSN: 1572-9540
    Keywords: muon-catalyzed fusion ; muonic hydrogen ; muonic atoms ; muonic molecules
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Preliminary results are reported for an experiment at TRIUMF where a time-of-flight technique was tested for measuring the energy dependence of the rate for muon-catalyzed dt fusion. Muonic tritium atoms were created following transfer of negative muons from muonic protium in a layer of solid hydrogen (protium) containing a small fraction of tritium. The atoms escaped from the solid layer via the Ramsauer-Townsend mechanism, traversed a drift region of 18 mm, and then struck an adjacent layer of deuterium, where the muonic atom could form a molecular system. The time of detection of a fusion product (neutron or alpha) following muon arrival is dependent upon the energy of the muonic tritium atom as it traverses the drift region. By comparison of the time distribution of fusion events with a prediction based on the theoretical energy dependence of the rate, the strength of resonant formation can in principle be determined. The results extracted so far are discussed and the limitations of the method are examined.
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  • 6
    ISSN: 1432-0851
    Keywords: Key words Gelonin ; Immunotoxins ; Chemotherapeutic agents ; Drug resistance ; Melanoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The development of cellular resistance to immunotoxins has been demonstrated in a variety of models and can involve a number of mechanisms. For the present study, an immunotoxin was utilized composed of an antimelanoma antibody ZME-018 recognizing a 240-kDa surface glycoprotein (gp 240) and the plant toxin gelonin. Human melanoma cells (A375-M) were grown in the presence of increasing amounts of ZME-gelonin and a clonal variant (A-375-ZR) was developed that was 100-fold resistant to ZME-gelonin compared to parental cells. Scatchard analysis showed that the A375-M parental cells had 260×103 ZME-gelonin-binding sites/cell with relatively low affinity (5 nM). In contrast, resistant A375-ZR cells demonstrated a reduced number of low-affinity sites (160×103/cell), but showed a small number (47×103) of higher-affinity sites (0.8 nM). Internalization rates and degradation rates of 125I-labeled ZME-gelonin were identical in both the parental and resistant cells. A375-ZR cells were found to be more resistant to vincristine and doxorubicin than were parental cells. Both cell lines were almost equally sensitive to native gelonin, 5-fluorouracil (5-FU), cisplatin, melphalan, carmustine, interferon γ (IFNγ) and IFNα. In addition, both cell lines were equally sensitive to another gelonin-antibody conjugate that binds to cell-surface, GD2 (antibody 14G2A). However, resistant cells were twice as sensitive to the cytotoxic effects of etoposide than were parental cells. Finally, a variety of agents were tested in combination with ZME-gelonin against A375-ZR cells in an attempt to identify agents to augment immunotoxin cytotoxic effects against resistant cells. The agents 5-FU, cisplatin, IFNγ, IFNα, and etoposide were the most effective in augmenting the cytotoxicity of ZME-gelonin against resistant cells. These studies suggest that development of resistance to one immunotoxin does not cause development of cross-resistance to other gelonin immunotoxins. Further, specific biological response modifiers and chemotherapeutic agents may be effective in augmenting the effectiveness of immunotoxins and specifically targeting or reducing the emergence of immunotoxin-resistant cells.
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  • 7
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The distribution of thiamine pyrophosphatase (TPPase) activity in the acinar cells of the rat sublingual gland has been studied at various stages of the secretory cycle following stimulated secretion. The rats were stimulated to secrete by an intraperitoneal injection of isoproterenol and pilocarpine. In non-stimulated glands, TPPase activity is detected mainly in 3–4 cisternae at the inner concave side of the Golgi complex and in some adjacent condensing vacuoles as in other cells. In the acinar cells 1 to 2 h after stimulation, however, reaction product for the same enzyme activity is detected in the cisternae at the outer aspect, as well as the inner aspect, of the Golgi complex and even in the cisternae of the endoplasmic reticulum (ER). About 4 h after stimulation, TPPase activity becomes concentrated in 3–4 disternae at the inner concave side of the Golgi complex as in the acinar cells under non-stimulated conditions. Morphological observations of the acinar cells 1 to 2 h after the stimulation have indicated that the reorganization of the Golgi complex and ER is a major event which occurs at this stage. It is possible that this cellular event is related to the occurrence of TPPase activity in those sites which normally show negative reaction in non-stimulated state.
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  • 8
    ISSN: 1434-3916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Recent reports in the literature strongly support the idea that cement is the optimum form of fixation of the femoral component in total hip replacement. For hybrid total hip arthroplasty, we used a cemented cup instead of an uncemented cup since this was inevitable in cases of poorly developed acetabulum. The uncemented cone femoral component is also beneficial in cases of extremely narrow and cylindrical configuration of the medullary cavity of untreated congenital dislocation of the hips (CDH) and tuberculosis or septic arthritis in childhood. We reviewed the clinical result of a consecutive series of patients with cemented total hip arthroplasty (THA) compared with recent studies on hybrid reconstruction using survivorship analysis. This subsequent study involved a hybrid uncemented Wagner cone femoral component and a cemented acetabular component with roof reinforcement by additional impacted cancellous allograft with hydroxyapatite (HA). We believe that early failure of the cemented components was due to an adverse effect of thin cement mantles around cemented femoral stems as well as the cemented cup in THA. In addition, 8 patients who received our modification of the Charnley CDH component had poor results even though we reduced the stem geometry and thickness. Furthermore, intraoperative fracture and splitting of the proximal femur was a major complication during implantation. Contrary to expectations, the results of these hybrid reconstructions were extremely encouraging (average follow-up period of 2–4.5 years). In addition to our experience of the cemented versus hybrid THA involving the uncemented Wagner femoral component, we have determined positive indications for the untreated and severely distorted anatomy of bilateral CDH for which surgical interventions for reconstruction were not recommended before.
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  • 9
    ISSN: 1432-5195
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé. A cause de l’idée selon laquelle la thrombose veineuse profonde post-opéraloire est rare parmi les patients asiatiques, la tromboprophylaxie pour les patients opérés est inhabituelle. Nous avons accompli une étude, comparant la prophylaxie au moyen d’héparine de bas poids moléculaire en utilisant du calcium nadroparine (Fraxiparine Sanofi France) et la non-prophylaxie sur 100 patients subissant un remplacement total de la hanche. Les patients ont subi une vénographie bilatérale avant l’opération et 10 jours après. Huit patients (16%) ont développé une thrombose veineuse dans le groupe de contrôle, contre 1 (2%) dans le groupe traité (p = 0.015, 95% CI 0.02 – 0.67). Trois embolies pulmonaires sont survenues dans le groupe de contrôle et 1 dans le groupe traité (p = 0.27 95% CI 0.04 – 2.44) aucune n’étant fatale. La perte de sang intra-opératoire et post-opératoire n’a pas varié de manière significative entre les deux groupes. Notre étude démontre que l’incidence de la thrombose veineuse profonde post-opératoire chez les patients asiatiques est notable bien qu’elle soit moindre que dans les pays occidentaux et confirme la sûreté et l’efficacité du calcium nadroparine pour la prévenir aprés un remplacement total de la hanche.
    Notes: Summary. Because of the belief that post-operative deep vein thrombosis (DVT) is rare in Asian patients, thromboprophylaxis is not usually prescribed for surgical patients. This study reports an open multi-centre controlled study of the use of a low molecular weight heparin, nadroparin calcium (Fraxoparine Sanofi France), as opposed to no prophylaxis in 100 patients undergoing uncemented total hip replacement. The patients had bilateral venography performed preoperatively and 10 days after operation. Eight patients (16%) developed DVT in the control group of 50 patients and 1 (2%) in the treatment group, also of 50 patients. Pulmonary embolus occurred in 1 patient in the treatment group and in 3 in the control group. Intraoperative and postoperative blood loss did not differ significantly between the two groups. Our study suggests that the incidence of DVT in Asian patients, though somewhat less than in their Western counterparts, is still considerable. It confirms the safety and efficacy of nadroparin calcium in preventing post-operative DVT in patients undergoing elective total hip replacement.
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  • 10
    ISSN: 1434-3916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Recent reports in the literature strongly support the idea that cement is the optimum form of fixation of the femoral component in total hip replacement. For hybrid total hip arthroplasty, we used a cemented cup instead of an uncemented cup since this was inevitable in cases of poorly developed acetabulum. The uncemented cone femoral component is also beneficial in cases of extremely narrow and cylindrical configuration of the medullary cavity of untreated congenital dislocation of the hips (CDH) and tuberculosis or septic arthritis in childhood. We reviewed the clinical result of a consecutive series of patients with cemented total hip arthroplasty (THA) compared with recent studies on hybrid reconstruction using survivorship analysis. This subsequent study involved a hybrid uncemented Wagner cone femoral component and a cemented acetabular component with roof reinforcement by additional impacted cancellous allograft with hydroxyapatite (HA). We believe that early failure of the cemented components was due to an adverse effect of thin cement mantles around cemented femoral stems as well as the cemented cup in THA. In addition, 8 patients who received our modification of the Charnley CDH component had poor results even though we reduced the stem geometry and thickness. Furthermore, intraoperative fracture and splitting of the proximal femur was a major complication during implantation. Contrary to expectations, the results of these hybrid reconstructions were extremely encouraging (average follow-up period of 2–4.5 years). In addition to our experience of the cemented versus hybrid THA involving the uncemented Wagner femoral component, we have determined positive indications for the untreated and severely distorted anatomy of bilateral CDH for which surgical interventions for reconstruction were not recommended before.
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