Correlation of diets high in n-6 polyunsaturated fatty acids with high growth rate in zebrafish (Danio rerio).
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Animal Feed↗
Biomedical subjects
M Wirth
Publications and source records attributed to M Wirth.
Bioavailability and metabolism of mometasone furoate following administration by metered-dose and dry-powder inhalers in healthy human volunteers.
These studies were conducted to assess the systemic bioavailability of mometasone furoate (MF) administered by both the dry-powder inhaler (DPI) and the metered-dose inhaler with an alternate propellant (MDI-AP). The pharmacokinetics of single doses (400 micrograms) of MF administered by intravenous (i.v.) and inhalation routes was assessed in a randomized, three-way crossover study involving 24 healthy volunteers. In a separate study, 6 healthy subjects were administered a single dose of tritiated (3H-) MF by DPI, and the radioactivity in blood, urine, feces, and expired air was determined. Following i.v. administration, MF was detected in all subjects for at least 8 hours postdose. The half-life (t1/2) following i.v. administration was 4.5 hours. In contrast, following DPI administration, plasma MF concentrations were below the limit of quantification (LOQ, 50 pg/mL) for many subjects (10 of 24), and the systemic bioavailability by this route was estimated to be less than 1%. Only two plasma samples following MDI-AP administration had plasma concentrations of MF above the LOQ indicating no detectable systemic bioavailability in 92% of the subjects. A separate study with 6 healthy male subjects administered a single dose of 3H-MF (200 microCi) by DPI revealed that much of the dose (approximately 41%) was excreted unchanged in the feces (0-72 hours), while that which was absorbed was extensively metabolized. These results indicate that inhaled MF has negligible systemic bioavailability and is extensively metabolized and should therefore be well tolerated in the chronic treatment of asthma.
Absorption↗
Cell lines with reduced UDP-N-acetylhexosamine pool in the presence of ammonium.
The glycosylation of pharmaglycoproteins from recombinant cell lines can be affected by an uncontrolled accumulation of ammonium in the medium. Glucosamine-6-phosphate isomerase (GPI) has been proposed as the key enzyme responsible for elevating the intracellular UDP-N-acetylhexosamine pool (UDPGNAc) by accepting ammonium from the medium of cultured mammalian cells. As previously reported, the increased UDPGNAc pool then affects the N-glycan complexity in glycoproteins. To understand the entry of extracellular ammonium into the cellular metabolism, GPI has been isolated to homogeneity from BHK-21 cells and characterized. Thus, the complete pathway by which ammonium enters the cellular metabolism was elucidated. To reduce the negative effects of ammonium, GPI was inhibited using two different strategies. First, the addition of mannose to the culture media and, second, antisense RNA expression. In both cases, the cellular UDPGNAc pool was suppressed in the presence of high ammonium concentrations in the medium. However, constant suppression of the UDPGNAc pool could not be achieved by antisense RNA expression because antisense clones were apparently unstable. Further studies showed that the main reason for instability was the inducibility of GPI by its substrate ammonium. GPI was induced to a factor of two under ammonium-containing medium conditions. We propose gene knockout technology for GPI repression to obtain cell lines consisting of an UDPGNAc pool unaffected by the presence of ammonium.
Aldose-Ketose Isomerases↗
Poly(D,L-lactic-co-glycolic acid) microspheres for sustained delivery and stabilization of camptothecin.
Camptothecin (CPT) and its water-insoluble derivatives are known as topoisomerase-I inhibitors exhibiting high antitumoral activity against a wide spectrum of human malignancies. Until now clinical application of CPT is restricted by insolubility and instability of the drug in its active lactone form resulting in less antitumor potency and poor bioavailability. For these reasons CPT-loaded-microspheres were prepared by the solvent evaporation method using the H-series of poly(D,L-lactide-co-glycolide) (H-PLGA), which contain more carboxylic acid end chains and hydrate faster than the non-H-series. At 1.2% CPT-payload the drug was molecular dispersed throughout the matrix whereas at higher CPT-payload the amount of crystalline CPT-islets increased with the CPT content. The release pattern of CPT was biphasic comprising a first burst effect delivering 20-35% of the payload and increasing with drug-loading. This phase was followed by sustained delivery of CPT releasing 40-75% of the payload within 160 h. In comparison to PLGA-microspheres, the CPT-release rate from H-PLGA was twofold higher and accelerated. The active CPT-lactone was maintained during preparation, storage and release due to hindered diffusion of acidic oligomers among other mechanisms. Thus stabilization and sustained release of CPT from PLGA-microspheres might reduce local toxicity combined with prolonged efficacy offering new perspectives in CPT chemotherapy.
Antineoplastic Agents, Phytogenic↗
Improvement of the primary metabolism of cell cultures by introducing a new cytoplasmic pyruvate carboxylase reaction.
Continuous mammalian cell lines are important hosts for the production of biological pharmaceuticals. However, these cell lines show some severe disorders in primary metabolism, which they have in common with many cancer cells. This leads to a high throughput of substrates giving a low energy yield and ample toxic side products such as lactate and ammonia. Because the enzymatic connection between glycolysis and the tricarboxylic acid cycle (TCA) is very poor, glucose is mainly degraded via oxidative glycolysis. It will be shown that introducing a pyruvate carboxylase gene expressed in the cytoplasma into a continuous BHK-21 cell line, and thus reconstituting the missing link between glycolysis and TCA, can reduce this problem. Thus, glucose consumption could be reduced by a factor of four and glutamine utilization up to a factor of two, compared with control. Moreover, a 1.4-fold-higher adenosine triphosphate (ATP) content was achieved. The flux of labeled [(14)C]-glucose into the TCA is shown to be enhanced, indicating a higher rate of oxidative glucose degradation. Host cell lines with an improved energy metabolism will therefore result in better exploitation of substrates, an increasing yield by the more efficient use of carbon source, and higher product integrity combined with lower production costs.
Adenosine Triphosphate↗
[Early recognition of prostate carcinoma. Initial results of a prospective multicenter study in Germany. Project Group for Early Detection DGU-BDU Laboratory diagnosis Professional Circle].
To compare the efficacy of digital rectal examination (DRE) and serum prostate specific antigen (PSA) in early detection of prostate cancer, we initiated a prospective multicenter screening trial. In 12,542 men choosen at random with a mean age of 62 (+/- 7.5) a suspect DRE or a PSA level > 4.0 ng/ml was found in 2343 (20%). Of the presently performed 744 biopsies, 157 revealed diagnosis of prostate cancer. Although further biopsies as well as the follow up of the 12,542 men are still missing, combination of DRE and PSA value > 4.0 ng/ml appears to be superior to DRE alone with a positive predictive value of 50% versus 19% in early detection of prostate cancer.
Aged↗
[Lymph node positive prostate carcinoma. A case for radical prostatectomy].
Lymph node positive carcinoma of the prostate (stage pN +/D1) is generally considered to be systemic disease that cannot be cured by radical prostatectomy. Treatment options in these minimally metastasized tumors are the wait and watch strategy, hormonal therapy, radiotherapy and radical prostatectomy alone or in combination. At present, there are no prospective randomized trials available regarding the value of these treatment modalities. In retrospective studies, the results of radical prostatectomy seem to be superior to conservative management. In several studies comparing radical prostatectomy vs. pelvic lymphadenectomy alone, a higher tumor burden in the lymphadenectomy alone groups is present. In general, radical prostatectomy reduces local complications of prostate carcinoma and improves quality of life. In conclusion, patients with single or low volume lymph node metastases as well as patients with low tumor grade or favorable Gleason score and diploid tumors seem to benefit from radical prostatectomy. However, the definitive role for radical prostatectomy has to be stated as uncertain.
Combined Modality Therapy↗
An LC/MS/MS method for the quantitation of MTIC (5-(3-N-methyltriazen-1-yl)-imidazole-4-carboxamide), a bioconversion product of temozolomide, in rat and dog plasma.
A sensitive and selective HPLC/electrospray ionization tandem mass spectrometric (LC/ESI/MS/MS) method for the quantitative determination of MTIC (5-(3-N-methyltriazen-1-yl)-imidazole-4-carboxamide), a pharmacologically active hydrolysis product of temozolomide, was developed and validated over a linear range from 10 to 400 ng ml(-1) in dog plasma and from 10 to 500 ng ml(-1) in rat plasma. This HPLC method utilized small plasma volumes (70 microl), rapid sample processing, and isocratic elusion conditions to achieve sensitive and selective MS/MS detection. Samples were processed and analyzed one at a time every 4.5 min in order to compensate for the inherent instability of MTIC. Both MTIC and the internal standard DTIC [5-(3,3'-N,N'-dimethyltriazen-1-yl)-imidazole-4-carboxamide] were quantitated in the positive ion, selected reaction monitoring (SRM) mode. The lower limit of quantitation (LLOQ) was 10 ng ml(-1) in the plasma from both species. Inter-assay accuracy and precision of all calibration standards and quality control (QC) samples were within +/- 11 and 12%, respectively, with the exception of the LLOQ in rat plasma (17%). The validated method was used to determine the time dependent plasma concentration of MTIC in rats and dogs following a single oral dose of temozolomide. The standard curve and the quality control data indicate that the method performed acceptably throughout the sample analysis period.
Animals↗
A review of studies of hormonal adjuvant therapy in prostate cancer.
There is increasing interest in the use of adjuvant hormonal therapies, which are given after the resection or destruction of all gross disease, in early-stage prostate cancer, as a significant proportion of patients experience progression and/or die from the disease despite undergoing therapy with curative intent. Several retrospective studies suggest that adjuvant hormonal therapy may improve long-term outcome after radical surgery in men with positive lymph nodes, although this approach has yet to be studied in a prospective setting. No studies of adjuvant therapy for patients with extracapsular extension at surgery have been completed, but in an interim analysis of an open controlled trial, adjuvant flutamide significantly improved progression-free survival at 4 years. Three prospective studies in the radiotherapy setting have shown that adjuvant luteinizing hormone-releasing hormone (LH-RH) agonist therapy significantly improves progression-free and/or overall survival. Future studies need to define patient subgroups who will benefit most from adjuvant therapy. The side effects of the different therapeutic options also need to be compared. It is hoped that many of the outstanding questions concerning adjuvant hormonal therapy will be answered by the ongoing Bicalutamide Early Prostate Cancer Programme.
Antineoplastic Agents, Hormonal↗
Absorption, metabolism, and excretion of 14C-temozolomide following oral administration to patients with advanced cancer.
The purpose of this study is to characterize the absorption, metabolism, and excretion of carbon 14-labeled temozolomide (14C-TMZ) administered p.o. to adult patients with advanced solid malignancies. On day 1 of cycle 1, six patients received a single oral 200-mg dose of 14C-TMZ (70.2 microCi). Whole blood, plasma, urine, and feces were collected from days 1-8 and on day 14 of cycle 1. Total radioactivity was measured in all samples. TMZ, 5-(3-methyltriazen-1-yl)imidazole-4-carboxamide (MTIC), and 4-amino-5-imidazole-carboxamide (AIC) concentrations were determined in plasma, and urine and plasma samples were profiled for metabolite/degradation products. Maximum TMZ plasma concentrations were achieved between 0.33 to 2 h (mean, 1.2 h), and half-life, apparent volume of distribution, and oral clearance values averaged 1.9 h, 17 liters/m2, and 104 ml/min/m2, respectively. A first-order absorption, one-compartment linear model, which included first-order formation of MTIC from TMZ and elimination of MTIC via degradation to AIC, and a peripheral distribution compartment for AIC, adequately described the plasma TMZ, MTIC, and AIC concentrations. MTIC systemic clearance was estimated to be 5384 ml/min/m2, and the half-life was calculated to be 2.5 min. Metabolite profiles of plasma at 1 and 4 h after treatment showed that 14C-derived radioactivity was primarily associated with TMZ, and a smaller amount was attributed to AIC. Profiles of urine samples from 0-24 h revealed that 14C-TMZ-derived urinary radioactivity was primarily associated with unchanged drug (5.6%), AIC (12%), or 3-methyl-2,3-dihydro-4-oxoimidazo[5,1-d]tetrazine-8-carboxyl ic acid (2.3%). The recovered radioactive dose (39%) was principally eliminated in the urine (38%), and a small amount (0.8%) was excreted in the feces. TMZ exhibits rapid oral absorption and high systemic availability. The primary elimination pathway for TMZ is by pH-dependent degradation to MTIC and further degradation to AIC. Incomplete recovery of radioactivity may be explained by the incorporation of AIC into nucleic acids.
Absorption↗
Lectin-mediated bioadhesion: binding characteristics of plant lectins on the enterocyte-like cell lines Caco-2, HT-29 and HCT-8.
In order to take advantage of the biorecognition between lectins and specific carbohydrates for targeted drug delivery, fluorescein-labelled lectins of different carbohydrate specificities were screened for binding to human colorectal carcinoma cell lines by flow cytometry and confocal microscopy. The lectin-binding rate increased as follows: Dolichos biflorus agglutinin, DBA<peanut agglutinin, PNA<Lens culinaris agglutinin, LCA<Solanum tuberosum lectin, STL<Ulex europaeus isoagglutinin I, UEA-I<wheat germ agglutinin, WGA (Caco-2); PNA<UEA-I<WGA (HT-29); DBA<UEA-I<WGA (HCT-8), thus reflecting the glycosylation pattern of the cells. Compared to the BSA-binding capacity of the cells, the extent of nonspecific binding was strongly dependent on the type of cell line and lectin under investigation being lower than 2% in the case of WGA, STL and UEA-I/Caco-2 and HT-29 cells. Whereas 50% of DBA was bound nonspecifically to Caco-2 cells, the interactions DBA/HCT-8 and PNA/HT-29 were due to nonspecific binding. By competitive inhibition of lectin-adhesion to the cells upon addition of the complementary carbohydrate, specificity of lectin-binding was confirmed except for the interaction of DBA/HCT-8 and PNA/HT-29. Following on from this work, we consider WGA-, STL- and UEA-I-mediated drug delivery to be a promising approach for peroral bioadhesive formulations adhering to absorptive enterocytes.
Caco-2 Cells↗
[What should be done in positive margins after radical prostatectomy?].
In the last years radical retropubic prostatectomy has become the treatment of choice for locally confined prostate cancer (PCa). However, in the literature local recurrence is described in 4-23% of patients with clinical stage T1-2 prostate cancer and in 43% of patients with clinical stage T3 respectively. The problem is further aggravated that postoperatively raised PSA values are detected in 6-8% of patients with locally confined prostate cancer indicating either local residual tumor or systemic disease. Current datas show that wait-and-watch appears to be the best option for patients with locally confined prostate cancer and positive margins. In case of persistent or raising PSA-values following prostatectomy without detectable local recurrence or metastasis mere local therapy cannot be recommended. Primary radiotherapy should be considered in cases with confirmed clinical local recurrence without distant metastasis. Further prospective and randomized trials have to be initiated to identify the patients with positive margins who will benefit from adjuvant treatment.
Biomarkers, Tumor↗
Dose intensification of epidoxorubicin and cyclophosphamide in metastatic breast cancer: a randomised study with two schedules of granulocyte-macrophage colony stimulating factor.
A randomised phase II/III study was conducted in patients with advanced breast cancer to determine the dose intensity achievable through an acceleration of administration of chemotherapy with epidoxorubicin and cyclophosphamide (EC) alone, as compared with the combination of this regimen with two different schedules of granulocyte-macrophage colony stimulating factor (GM-CSF). 73 patients received EC intravenous (i.v.) (epidoxorubicin 100 mg/m2, cyclophosphamide 600 mg/m2) on day 1 (group A), or the same chemotherapy plus sub-cutaneous (s.c.) GM-CSF (5 micrograms/kg/day) either from days 3 to 12 (group B) or from days -6 to -3 (group C). The primary objective of the study was the investigation of dose intensity delivered in the three treatment arms, whereas the secondary objective was response rate. A significant increase (P = 0.006) in dose intensity of 21% was observed for treatment group B, whereas the increase in dose intensity achieved in group C (7%) was not significant (P = 0.086). Response rates (complete response (CR) + partial response (PR)) of 56% were observed in group A, 65% in group B, and 57% in group C, respectively. This difference in response rates did not reach statistical significance (P = 0.271). We thus conclude that an acceleration of the EC regimen over the standard schedule could be accomplished with postchemotherapeutic GM-CSF support, leading to an increase in dose intensity, whereas pretherapeutic short-term GM-CSF administration did not reach this goal.
Adolescent↗
Lectin-mediated drug targeting: preparation, binding characteristics, and antiproliferative activity of wheat germ agglutinin conjugated doxorubicin on Caco-2 cells.
PURPOSE: To investigate the usefulness of wheat germ agglutinin as a targeting carrier protein for an acid-labile chemotherapeutic prodrug directed against colon carcinoma cells in vitro. METHODS: Cis-aconityl-linked doxorubicin-wheat germ agglutinin was prepared by a two step procedure and the conjugate-binding capacity of target- and non-target cells was assayed by flow cytometry. The antiproliferative activity of the prodrug on Caco-2 and MOLT-4 cells was determined by the XTT- and BrdU-test and compared with that of the parent drug and the lectin alone. RESULTS: At pH 4.0, about 50% of the conjugated doxorubicin were released within 24 h from the water soluble prodrug exhibiting a conjugation number of 24 (mol doxorubicin/mol WGA). The prodrug-binding capacity of colon carcinoma cells exceeded that of human colonocytes and lymphoblastic MOLT-4 cells 4.5-fold. Additionally, the antiproliferative effect of the conjugate on Caco-2 cells was 39% as opposed to 5% in case of MOLT-4 cells. As the unmodified carrier protein inhibited or stimulated Caco-2 cell growth in a concentration-dependent manner, the cytostatic activity of the conjugate was determined at WGA concentrations without an effect on cell-proliferation. Considering 50% release of conjugated drug at the most, the prodrug yielded 160% of the cytostatic activity of free doxorubicin. CONCLUSIONS: WGA-prodrug targeting offers new perspectives for site-specific, cytoinvading drug delivery in colon cancer chemotherapy.
Aconitic Acid↗
Coincidence of primary non-Hodgkin's lymphoma and invasive lobular carcinoma of the breasts--clinical diagnosis and management.
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Aged↗
Lectin-mediated drug targeting: quantification of binding and internalization of Wheat germ agglutinin and Solanum tuberosum lectin using Caco-2 and HT-29 cells.
For the potential use of Wheat germ agglutinin (WGA) and Solanum tuberosum lectin (STL) as auxiliary excipients for targeting drugs to colonocytes, the number of Caco-2 and HT-29-bound lectins was determined by fluorimetry using fluorescein-labelled derivatives of the N-acetylglucosamine-specific lectins. After 1 h of incubation, the WGA-binding capacity of 5 x 10(4) Caco-2 cells was 26.9 +/- 0.5 pmol at 4 degrees C and 27.2 +/- 1.0 pmol at 37 degrees C respectively. In comparison, 19.5 +/- 2.9 pmol (37 degrees C) and 16.7 +/- 0.9 pmol (4 degrees C) WGA were bound within 1 h to 5 x 10(4) HT-29 cells referring to about 80% of the total amount of WGA bound within 4 h of incubation. In contrast, binding of STL to the colon carcinoma cell lines was independent of incubation times and temperatures tested exhibiting a binding rate of 8.4 +/- 0.6 pmol (HT-29) and 9.9 +/- 0.8 pmol (Caco-2) STL/5 x 10(4) cells. As determined by flow cytometry, non-specific binding is lower than 1.0% (WGA) and 3.4% (STL). Uptake and intracellular accumulation of the lectins were investigated by confocal laser scanning microscopy at 4 degrees C and 37 degrees C respectively. A decrease of initially membrane-bound lectins concurrent with increasing cytoplasmic enrichment by time was observed by digital cell image analysis. Due to specific and numerically sufficient adhesion as well as internalization, WGA and STL are anticipated as targeting tools in lectin-mediated drug delivery systems.
Acetylglucosamine↗
[Do close but negative margins in radical prostatectomy specimens increase the risk of postoperative progression?].
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Biomarkers, Tumor↗