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  • 1
    ISSN: 0022-4731
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Biologie , Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 304 (1978), S. 277-281 
    ISSN: 1432-1912
    Schlagwort(e): Oxalate excretion ; Probenecid ; Micropuncture ; Microperfusion ; Rat kidney
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Clearance and micropuncture experiments were performed in rats to study the renal handling of oxalate. The 14C-oxalate to 3H-inulin clearance ratio (C ox /C in ) was 1.36±0.04 and was lowered by probenecid (200 mg/kg) to 1.11±0.03 (±S.E., n=6, P〈0.005). an attempt was made to localize the assumed secretion of oxalate in three different micropuncture protocols. In free flow micropuncture experiments single nephron clearance of oxalate was not different when obtained from proximal or distal tubular puncture sites. The fractional delivery of oxalate averaged 0.84 ±0.03 regardless of the puncture site from midproximal to late distal. This finding indicates a net outflux of oxalate in an early proximal loop since oxalate is freely ultrafilterable. In microperfusion experiments the mean recovery of oxalate ranged from 79–90%. The outflux of oxalate correlated linearly with the tubular load (r=0.95). The results suggest that no net secretion occurs in superficial nephron segments accessible for micropuncture. Since whole kidney clearances of oxalate always exceeded glomerular filtration rate, it is concluded that net addition of oxalate into the tubular fluid can occur at sites beyond the superficial late distal tubules or is due to higher delivery of oxalate by deep cortical nephrons.
    Materialart: Digitale Medien
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  • 3
    ISSN: 1433-0563
    Schlagwort(e): Key words Bladder cancer • Lymph node staging • Positron emission tomography • FDG ; Schlüsselwörter Harnblasenkarzinom • Lymphknotenstaging • Positronenemissionstomographie • FDG
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Die Positronenemissionstomographie (PET) stellt ein neues bildgebendes Verfahren dar, mit der Stoffwechselvorgänge und nicht morphologische Veränderungen untersucht werden können. Da Tumoren eine erhöhte Glykolyse aufweisen, können diese mittels radioaktiv markierter Glukose und PET nachgewiesen werden. Dieser Ansatz hat sich bereits bei unterschiedlichen Tumorentitäten bewährt. In dieser Studie wurde die PET beim Lymphknotenstaging des Harnblasenkarzinoms untersucht. Bei 64 Patienten wurde präoperativ eine PET des Beckens nach i. v.-Injektion von Fluor-Deoxy-Glukose (FDG) durchgeführt, so daß der PET-Befund mit dem histologischen Befund des Operationspräparates nach klassischem operativen Lymphknotenstaging verglichen werden konnte. Beim Lymphknotenstaging wurden bei 14 Patienten positive Lymphknoten richtig erkannt; ein falsch-negatives Ergebnis trat bei 7 Patienten auf. Bei 37 Patienten wurden die Lymphknoten als richtig-negativ bewertet, 6mal war ein falsch-positives Ergebnis erzielt worden. Aus diesen Daten errechnet sich eine Sensitivität von 67 %, eine Spezifität von 86 % und eine Treffsicherheit von 80 %. Somit sind die PET-Ergebnisse ermutigend und scheinen besser zu sein als die klassischen Stagingverfahren, wie CT und MRT.
    Notizen: Summary PET is a new method in nuclear medicine which examines the metabolism and not the morphology. Tumors show a higher rate of glycolysis than benign tissue and hence can be detected by radioactive glucose. This method has proved good for various tumors. In this study the lymph node staging of bladder cancer by PET was investigated. In 64 patients a PET of the pelvis after injection of fluorodeoxyglucose (FDG) was carried out preoperatively; the PET-results were compared with the histology of the OR specimen after classical pelvic lymphadenectomy. For lymph node staging positive nodes were found in 14 patients which was correct; a false-negative result was obtained in 7 patients. In 37 patients the PET-result was true-negative and in 6 patients false-positive resulting in a sensitivity of 67 %, a specificity of 86 % and an accuracy of 80 %. Therefore, our PET results are encouraging and seem to be better than those obtained by classical staging procedures such as CT or MRI.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    s.l. ; Stafa-Zurich, Switzerland
    Advanced materials research Vol. 6-8 (May 2005), p. 517-524 
    ISSN: 1662-8985
    Quelle: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Thema: Maschinenbau
    Notizen: The manufacturing technique of driving is one of the oldest procedures for sheet metal forming and has been used in the ancient world for the production of copper pots and vases. This technique is still utilized for niche applications but today has lost its importance. The process of driving is almost completely carried out manually and thus is only appropriate for very small quantities or in case of failure of other production processes. Since individualization of products is strongly gaining in significance, forming processes have to be found, which are independent from expensive tools and equipment. Using driving as the process of choice to form sheet metal, the grade of automation of the forming process has to be increased. Numerically controlled driving, i.e. automated positioning and handling of the work piece during the production process, will need a conclusive simulation base. This paper provides results of the analysis of sheet steel angles formed by the driving sub groups of shrinking and stretching
    Materialart: Digitale Medien
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  • 5
    ISSN: 1432-1440
    Schlagwort(e): Germ cell tumors ; Gonadal toxicity ; Chemotherapy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The impact of aggressive chemotherapy on reproductive and endocrine gonadal function was prospectively studied in 44 patients with germ cell tumors. Diagnostic procedures to determine gonadal toxicity consisted of hormone determinations, semen analyses, interviews with a standardized questionnaire, and gonadal histology. After chemotherapy all patients showed elevated serum levels of follicle-stimulating hormone (FSH) and azoospermia due to germ cell and stem cell loss. Recovery of spermatogenesis, as indicated by normalization of serum FSH levels and sperm density, occurred in 77% of the patients 25–60 months after cessation of chemotherapy. In all patients serum testosterone and luteinizing hormone (LH) values remained within normal limits after therapy indicating resistance of Leydig cells to cytotoxic drugs. Three patients fathered four healthy children after completion of chemotherapy. These data suggest significant reproductive dysfunction in all men treated for germ cell tumors. However, most patients showed late and complete recovery of spermatogenesis. In contrast, endocrine gonadal function was unaffected after chemotherapy in all patients. FSH and LH are feasible markers to assess drug-induced gonadal toxicity.
    Materialart: Digitale Medien
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  • 6
    ISSN: 1432-1335
    Schlagwort(e): Interferon plus MPA ; Advanced renal cell cancer ; Medroxyprogesterone acetate (MPA)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The response rates in metastatic renal cell cancer (RCC) after chemotherapy, hormonal treatment, or immunotherapy rarely exceed 15%. Recently, interferon alpha (IFNα) was used for treatment of this disease in several studies which also demonstrated response rates of 15%. In order to test whether IFN therapy combined with hormones would result in higher response rates we compared single agent IFN therapy with a combined therapy of rIFNα 2C plus medroxyprogesterone acetate (MPA) in a randomized multicenter trial. The rIFNα 2C (2MU) was given s.c. 5 times per week for 8–12 weeks and subsequently once weekly until week 48. In the combined treatment, 750 mg MPA was given p. o. daily until week 48 in addition to the IFN as described. The overall response rate in 93 evaluable patients was 5.4%, corresponding to 2 complete and 3 partial responses. Median survival was 7 months in both treatment groups. These data confirm the ineffectivity of low IFN doses for treatment of RCC. The low response rate is not increased by addition of MPA to IFN. The analysis of other IFN studies suggests that not only IFN doses but also IFN sources may influence response rates in metastatic RCC.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Urological research 19 (1991), S. 353-356 
    ISSN: 1434-0879
    Schlagwort(e): Bladder cancer ; Electron microscopy ; Photodynamic therapy ; Photosan ; Phototoxicity ; Tumor selectivity ; Video fluorescence microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The uptake of photosan and the intracellular sites of photoradiation-induced damage were investigated in vitro in bladder carcinoma cells and in normal bladder cells. Cells were examined by phase contrast, fluorescence and electron microscopy. The concentration of photosan, measured in μg/106 cells, showed a good correlation to the incubation time. At all incubation times, control cells showed a lower uptake when compared with tumor cells. Following photodynamic therapy (PDT), phase-contrast microscopy revealed marked changes in tumor cells, whereas only minor effects could be detected at the cell membrane of the control cells. Following PDT, most of the investigated cells showed onanges of the mitochondria and cytoplasma. These changes consisted of dissolution of the cristae, predominantly in the central part of the mitochondria. Twenty-four hours after PDT the shape of the mitochondria had changed markedly and the cristae were found to be completely destroyed. Moreover, the cystoplasma showed numerous vacuoles, and the number of mitochondria was decreased compared to non-treated cells.
    Materialart: Digitale Medien
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  • 8
    ISSN: 1434-0879
    Schlagwort(e): Photodynamic therapy ; Porphycene ; pH-sensitive liposomes ; Transmission electron microscopy ; Scanning electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract In vitro experiments were performed on human bladder carcinoma cells to evaluate the efficiency of the recently synthesized photosensitizer 9-acetoxy-tetra-n-propylporphycene (ATPPn) for photodynamic therapy. To improve cytoplasmic delivery of this hydrophobic compound, we prepared pH-sensitive liposomes composed of phosphatidylethanolamine (PE) and cholesteryl hemisuccinate (CHEMS) in comparison with pH-insensitive liposomes consisting of phosphatidylcholine (PC) and CHEMS. Dynamic light scattering measurements were used to monitor the acid-induced liposome destabilization. After incubation with liposome-bound ATPPn, bladder carcinoma cells were irradiated by a dye laser with increasing light fluence rates from 1 to 48 J/cm2. The photodynamic effects were then assessed from cell survival curves. No dark or phospholipid toxicity was measured for 2 μg ATPPn/1.5 ml medium. Qualitative cellular uptake of ATPPn was determined by fluorescence microscopy, while photodamage was elucidated by transmission and scanning electron microscopy. Absorption spectra performed up to 42 days revealed changes in shape for the pH-sensitive liposomes after storage at room temperature. ATPPn was proved to be an encouraging photosensitizer, capable of reducing cell survival to 0.1% after short-term incubation of 60 min with a drug dose of 2 μg ATPPn/1.5 ml medium. Although pH-sensitive PE/CHEMS liposomes showed significantly (P〈0.05) more photokilling effects at 24 J/cm2 and 48 J/cm2, no further advantages over non-pH-sensitive PC/CHEMS liposomes were found.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Urological research 22 (1994), S. 79-83 
    ISSN: 1434-0879
    Schlagwort(e): Phototoxicity ; Aluminum-chlorophtalocyanine ; Electron microscopy ; DAB staining
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract In vitro experiments were performed on human bladder carcinoma cells to evaluate the uptake of aluminum-chlorophthalocyanine (AlSPc) and the subcellular target of phototoxicity. In order to quantify the correlation of intracellular uptake and incubation time and to identify the primary subcellular target of phototoxicity, fluorescence and absorption measurements have been carried out as well as electron microscopic studies. Absorption and fluorescence measurements showed the largest value after 24 h of incubation time. Fluorescence microscopic studies suggested the sensitizer to be located in a brighter patch within cytoplasm. Electron microscopic studies using DAB (3,3′ diaminobenzidine) staining showed that the mitochondria are the primary target of phototoxic activity of AlSPc and that the majority of vacuoles of treated cells were originally mitochondria.
    Materialart: Digitale Medien
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  • 10
    ISSN: 1434-0879
    Schlagwort(e): Bladder carcinoma ; Tetramethyl hematoporphyrin ; Liposomes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The main problems presented by superficial bladder carcinoma, its high recurrence rate and multifocal appearance, require treatment of the bladder as a whole. Photodynamic therapy (PDT) is one such experimental treatment for superficial bladder carcinoma, involving the administration of a photosensitizer that accumulates in the tumor tissue, and subsequent irradiation of the tumor with light. Since the photosensitizers used in PDT suffer from several drawbacks, new photosensitizers are being sought. Drug delivery systems are also being investigated for the administration of hydrophobic photosensitizers and enhancement of photodynamic efficiency and tumor selectivity. In this study we examined a new photosensitizer, tetramethyl hematoporphyrin (TMHP), in two human bladder cancer cell lines. In the first pair of the experiments, TMHP was bound to unilamellar liposomes. Cellular uptake, dark toxicity and photodynamic efficiency were then studied. Fluorescence microscopy showed TMHP localization in the cytoplasm in a perinuclear region, sparing the nucleus. Dark toxicity occurred after incubation of cells with TMHP above a concentration of 20 μg/ml. Irradiation was carried out using an argon-pumped dye laser emitting a wavelength of 630 nm at a fluence of 3.6 and 7.2 J/cm2. Before irradiation, cells were incubated with TMHP at concentrations of 2.5 and 5 μg/ml for 1 h. Cell survival rates after incubation with 5 μg/ml TMHP and irradiation at 7.2 J/cm2 were 15.7% of control cells for Rec and 4.5% for Waf cells. Uptake studies showed a higher intracellular TMHP concentration in Waf than in Rec cells. This correlates with the higher PDT efficiency seen in Waf cells. Our results show that TMHP can be encapsulated into unilamellar liposomes without losing its photodynamic efficiency. TMHP is taken up by human bladder carcinoma cells after an incubation time of only 1 h. This short incubation time seems to be appropriate for an intravesical instillation of the photosensitizer for PDT in bladder cancer patients. Intravesical instillation might demonstrate higher phototoxic efficiency with reduced side effects. TMHP acts as a potent photosensitizer and shows drug- and light-dose-dependent cell destruction. Thus, TMHP has the potential for use in PDT in bladder cancer.
    Materialart: Digitale Medien
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