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Biomedical subjects

M Wirth

Publications and source records attributed to M Wirth.

At least 37 records · Page 2Linked to original sources
PubMed2003

Immediate treatment with bicalutamide 150mg as adjuvant therapy significantly reduces the risk of PSA progression in early prostate cancer.

OBJECTIVE: To evaluate the effect of bicalutamide ('Casodex') 150mg (in addition to standard care), on the risk of prostate-specific antigen (PSA) progression, in patients with early prostate cancer. METHODS: The bicalutamide 150mg Early Prostate Cancer (EPC) programme is the largest clinical trial programme in the treatment of prostate cancer to date. This paper reports the PSA progression data from the EPC programme at a median of 3years' follow-up, for the overall study population, and across the radical prostatectomy and radiotherapy primary therapy strategies. PSA progression was predefined as the earliest occurrence of PSA doubling from baseline, objective progression, or death from any cause. RESULT: Overall, bicalutamide 150 mg in addition to standard care significantly reduced the risk of PSA progression by 59% compared with standard care alone (HR 0.41; 95% CI 0.38, 0.45; p<<0.0001). Significant reductions were observed following radical prostatectomy (51%; HR 0.49; 95% CI 0.43, 0.56; p<<0.0001) and radiotherapy (58%; HR 0.42; 95% CI 0.33, 0.53; p<<0.0001). Further exploration of the data by disease stage, nodal status, Gleason score and pre-treatment PSA level revealed significant reductions in the risk of PSA progression across most prognostic risk factor subgroups. CONCLUSIONS: Bicalutamide 150mg significantly reduces the risk of PSA progression, irrespective of whether patients received radical prostatectomy or radiotherapy as standard care. The EPC programme is ongoing and further progression and survival data are awaited.

Adult↗
PubMed2003

[Paraneoplastic hyperthyroidism in a patient with metastasizing teratocarcinoma and excessively high HCG].

Clinically manifest hyperthyroidism is a rare paraneoplastic syndrome in patients with excessive HCG production due to testicular cancer. A 40-year-old patient with right testicular cancer (teratoma, embryonal cell carcinoma), diffuse pulmonary metastases and high serum HCG levels presented with symptomatic hyperthyroidism. The patient received immediately thyrostatic therapy and 4 cycles of PEI chemotherapy (Cisplatin, Etoposide, Ifosfamide). Thyroid function had returned to normal by the beginning of the second course of chemotherapy. After right orchiectomy and resection of residual pulmonary masses which revealed vital tumor cells, two additional courses of chemotherapy were performed. The patient is well and without evidence of disease 11 months after therapy. All patients with testicular cancer and excessive HCG production should be evaluated for biochemical and clinical signs of hyperthyroidism and treated accordingly with antithyroidal medication and immediate cytoreductive chemotherapy.

Adult↗
PubMed2002

Gantrez AN as a new polymer for the preparation of ligand-nanoparticle conjugates.

The aim of this study was to evaluate the feasibility and in vitro activity of ligand-conjugates based on the use of poly(methyl vinyl ether-co-maleic anhydride) (PVM/MA or Gantrez AN). Fluorescently labelled PVM/MA nanoparticles were prepared by desolvation and cross-linkage with 1,3-diaminopropane (DP). Conjugates were obtained by incubation between the carriers and Sambucus nigra agglutinin (SNA) for 1 h in an aqueous medium. The lectin binding to the surface of nanoparticles was increased by both increasing the bulk ligand concentration and decreasing the amount of cross-linker. However, a concentration of about 0.3-0.4 mg DP per mg polymer was necessary to obtain maximum agglutination activity. Under optimal conditions, the amount of fixed ligand was 46 microg/mg nanoparticle (binding efficiency of 86%); although the activity of SNA conjugates was 13.3 microg/mg particle. The activity of nanoparticles, measured by the association to Caco-2 monolayers, was higher when SNA was covalently bound onto their surface. The lectin-conjugate interaction was 6-fold higher than conventional nanoparticles. Moreover, energy-dependent mechanisms were only observed in SNA-PVM/MA particles. Finally, the decrease in association in the presence of lactose demonstrates that both SNA- and SNA-conjugate-binding was due to a true lectin-sugar interaction.

Animals↗
PubMed2002

Dynamic characterization of recombinant Chinese hamster ovary cells containing an inducible c-fos promoter GFP expression system as a biomarker.

An inducible reporter gene system for Chinese Hamster Ovary (CHO-DHFR(-)) cells has been developed and characterized with respect to its dynamic properties. The reporter gene system consists of the human c-fos promoter and variants of the green fluorescence protein (GFP), either EGFP with enhanced fluorescence or its destabilized form d2EGFP. The expression of wild-type EGFP or its destabilized form was studied in CHO-DHFR(-) cells in response to serum addition or deprivation. It was shown that serum-induced c-fos promoter mediated EGFP expression was considerably higher than expression from the human CMV promoter, a strong, constitutive promoter preferentially used for high-level expression in CHO cells. However, EGFP was less suitable for studying expression dynamics than d2EGFP due to the protein's long half-life in mammalian cells. The use of d2EGFP resulted in a significant improvement in the dynamic characteristics of the biomarker, particularly when the recombinant cells were selected for high-level GFP expression by subcloning or fluorescence activated cell/sorting (FACS). GFP expression in different subclones and cell populations sorted by FACS was characterized with respect to its dynamic responses in the presence or absence of serum in the culture medium. Significant differences in the GFP expression dynamics were observed for the isolated cell populations. The experimental results indicate that cells with high-level GFP expression also have a faster dynamic response and are thus, desirable for practical application of the reporter gene system e.g. in toxicity monitoring.

Animals↗
PubMed2002

Lectin-mediated drug delivery: influence of mucin on cytoadhesion of plant lectins in vitro.

As the mucous layer represents the first barrier to peroral lectin-mediated drug delivery, the influence of mucin on the cytoadhesive properties of lectins was studied in vitro by establishing a rapid and simple microplate format assay using pig gastric mucin (PGM) for coating the wells. The lectin-binding capacity of mucin followed the order WGA>>UEA-I>>LCA=STL>PNA>DBA. The PGM-binding of wheat germ agglutinin (WGA) was strongly dependent on pH being highest at pH 5.0. In comparison, PGM-binding of WGA was about 15% at gastric pH and 60-70% at intestinal pH. This points to unimpeded gastric transit of WGA-grafted formulations and favorable conditions within the intestine for binding to mucus coated enterocytes. Moreover the WGA-PGM interaction was concentration-dependent, specific and fully reversible. According to a competitive assay in the presence of Caco-2 monolayers, the PGM-binding of WGA was saturated and influenced by the lectin-concentration yielding 28% Caco-2 bound WGA (125 ng WGA/0.29 cm(2) monolayer) and 68% Caco-2 bound WGA (4 microg WGA/0.29 cm(2) monolayer), respectively. Following on from these results, lectins are expected to suffer at least partially from premature inactivation by shed off mucus like bioadhesives of the first generation, however initial but reversible mucus-binding of lectins offers partititioning to the cell membrane followed by uptake into the enterocyte.

Adhesives↗
PubMed2002

Lectin-mediated drug delivery: discrimination between cytoadhesion and cytoinvasion and evidence for lysosomal accumulation of wheat germ agglutinin in the Caco-2 model.

Lectin-mediated drug delivery may become a promising strategy to improve the efficacy of poorly permeable drugs by utilising active high-capacity transport pathways of epithelial tissues. This requires the elucidation of the basic mechanisms of lectin uptake prior to their practical use. We studied the interaction between the dietary lectin wheat germ agglutinin (WGA) and Caco-2 cells (single cells and monolayers) by a newly established assay design that is able to discriminate between cellular binding and uptake as well as by confocal microscopy: (i) All binding sites available for WGA at the cell membrane were occupied within 10 min of incubation. (ii) Cytoadhesion was followed by immediate uptake. After 20 min, 60% (single cells) or 30% (monolayers) of the membrane bound lectin were internalised. However, regardless of cell arrangement, 80% of the surface bound lectin was taken up into the cells during the course of the experiment. (iii) About 50% of the internalised lectin accumulated within the lysosomes after 1 h. This was confirmed by assays in the presence of monensin, an inhibitor of endosomal acidification, and by colocalisation with lysosomal cathepsin followed by semiquantitative image analysis. Further analysis by immunocytochemistry suggested that the trans-Golgi complex and the caveoli were not involved. Due to cytoadhesion, cytoinvasion and partial lysosomal accumulation, WGA-mediated drug delivery may provide for improved intracellular availability of conjugated drugs or colloidal carrier systems.

Caco-2 Cells↗
PubMed2001

The interaction between wheat germ agglutinin and other plant lectins with prostate cancer cells Du-145.

The bioadhesive properties of fluorescein-labeled plant lectins with different carbohydrate specificities were investigated by flow cytometry at 4 and 37 degrees C using Du-145 prostate cancer cells. At both temperatures the lectin association rate increased following the order: Dolichos biflorus agglutinin (DBA)<peanut agglutinin<Ulex europaeus isoagglutinin I<Lens culinaris agglutinin<Solanum tuberosum lectin << wheat germ agglutinin (WGA), reflecting the glycosylation pattern of Du-145 cells. Both, the BSA-binding capacity of the cells referring to nonspecific binding and inhibition studies using the complementary carbohydrate, assured specificity of the lectin-cell interactions except for DBA. The WGA-association rate of Du-145 cells was dependent on temperature indicative for cellular uptake of membrane-bound WGA. Intracellular enrichment of WGA was confirmed by confocal microscopy. As resulted from experiments in presence of ouabain active transport mechanisms were involved in cellular uptake of WGA. Equilibration of the intracellular pH with monensin pointed to accumulation of intracellular located WGA within acidic compartments of Du-145 cells such as the lysosomes or the trans-Golgi complex. Consequently the interaction of WGA with Du-145 cells at 37 degrees C is a one way process due to immediate active transport of membrane-bound lectin into acidic compartments of prostate cancer cells.

Adenocarcinoma↗
PubMed2001

Bicalutamide (Casodex) 150 mg as immediate therapy in patients with localized or locally advanced prostate cancer significantly reduces the risk of disease progression.

OBJECTIVES: To investigate the efficacy and tolerability of bicalutamide (Casodex) as immediate therapy, either alone or as adjuvant to treatment of curative intent, in patients with localized or locally advanced (T1b-T4, any nodal status, M0) prostate cancer. METHODS: This was a multicenter, prospective, randomized, double-blind, placebo-controlled trial in Europe, South Africa, Australia, and Mexico and is part of the Casodex Early Prostate Cancer program. RESULTS: A total of 3603 men were randomized to receive bicalutamide (n = 1798) or placebo (n = 1805). The patient demographics were well balanced between the two groups. Prior therapy of curative intent had been given to 64% of the patients (prostatectomy [44%], radiotherapy [18%], and prostatectomy and radiotherapy [2%]) and 36% had been monitored with watchful waiting. After a median follow-up of 2.6 years and a median exposure to the study drug of 2.2 years, a significant 43% reduction in the risk of objective progression was observed for the bicalutamide group compared with the placebo group (hazard ratio 0.57, 95% confidence interval 0.48 to 0.69, P << 0.0001). The time to prostate-specific antigen doubling was significantly delayed for the bicalutamide group compared with the placebo group (hazard ratio 0.37, 95% confidence interval 0.32 to 0.43, P << 0.001). The survival data were immature, with 7.2% overall mortality. The most frequently reported adverse events with bicalutamide were gynecomastia alone (17.4%), breast pain alone (17.6%), and gynecomastia with breast pain (47.5%). CONCLUSIONS: Bicalutamide 150 mg daily as immediate therapy, alone or as adjuvant to treatment of curative intent, significantly reduced the risk of disease progression in patients with localized or locally advanced prostate cancer. Longer follow-up is underway to assess any benefit in overall survival.

Adult↗
PubMed2001

The bicalutamide Early Prostate Cancer Program. Demography.

BACKGROUND: The optimal treatment for early prostate cancer has yet to be established. A well-tolerated hormonal therapy such as bicalutamide could be a useful treatment option in this setting, either as adjuvant or immediate therapy. A major collaborative clinical trials program was set up to investigate bicalutamide as a treatment option for local prostate cancer (localized or locally advanced disease). METHODS: The bicalutamide Early Prostate Cancer program comprises three randomized, double-blind, placebo-controlled trials of similar design that are being conducted in distinct geographical areas (North America; Australia, Europe, Israel, South Africa and Mexico; and Scandinavia). Men with T1b-4N0-1M0 (TNM 1997) prostate cancer have been randomized on a 1:1 basis to receive bicalutamide 150 mg daily or placebo. Recruitment to the program closed in July 1998, and follow-up is ongoing. Study endpoints include time to clinical progression, overall survival and tolerability. RESULTS: 8113 men aged 38 to 93 years (mean 66.9) were randomized over a 3-year period. 67.4% of the enrolled patients had localized disease (T1-2) and 66.4% had a Gleason score </=6 at study entry, while the majority of patients had node-negative (N0) disease; only 3.1% in two of the studies and none in the third study had confirmed N+ disease. Overall, 71.8% of the patients received therapy of primary curative intent within 16 weeks of randomization; the remainder received watchful waiting as their primary approach. Across the program, the two randomized groups are well balanced. CONCLUSION: This is the largest randomized clinical trial program to date in local prostate cancer and is expected to provide critical information on the role of bicalutamide as an addition to standard care for patients with local prostate cancer who have received a therapy of curative intent or are candidates for watchful waiting.

Journal Article↗
PubMed2001

Delaying/reducing the risk of clinical tumour progression after primary curative procedures.

The advent of prostate-specific antigen (PSA) testing and increased patient awareness has led to patients being diagnosed with prostate cancer at an earlier stage and a younger age than previously. Adjuvant hormonal therapy to radiotherapy or prostatectomy has been shown to reduce the risk of tumour progression, and in some studies survival benefits have been demonstrated. The non-steroidal antiandrogen bicalutamide ('Casodex') has undergone extensive evaluation and is currently undergoing clinical trials as immediate therapy, either alone or as adjuvant to treatment of curative intent in patients with localized or locally advanced disease. Data from the first analysis of one of the studies in the Early Prostate Cancer (EPC) programme involving 3,603 patients have shown that, after a median follow-up of 2.6 years, the risk of prostate cancer progression was significantly reduced (by 43%) in patients receiving bicalutamide 150 mg compared with those receiving standard care alone (HR 0.57; 95% CI 0.48, 0.69; p << 0.0001). The risk of PSA progression was also significantly reduced (by 63%). At this stage the survival data are still immature. Side effects of bicalutamide were mostly gynaecomastia and breast pain, which is consistent with its pharmacology. Overall withdrawal rates were similar in the bicalutamide 150 mg and standard care alone groups. In the bicalutamide 150 mg group, withdrawals were mainly due to side effects, whereas in the group receiving standard care alone, withdrawals were mainly due to disease progression. The programme is ongoing, and survival data are awaited.

Androgen Antagonists↗
PubMed2000

Development of a self-inactivating, minimal lentivirus vector based on simian immunodeficiency virus.

In contrast to oncoviruses, lentiviruses do not require target cell division for integration into the host genome. Lentiviral vectors can therefore expand the spectrum of target cells susceptible to retroviral gene transfer. To analyze whether vectors based on simian immunodeficiency viruses (SIVs) could be used for gene transfer, a three-plasmid vector-packaging system was developed, in which Gag-Pol and the vector itself are of SIV origin, while Env is derived either from SIV, amphotropic murine leukemia virus (MuLV), or the G glycoprotein of vesicular stomatitis virus (VSV-G). To increase the safety of the SIV vector system, a self-inactivating SIV vector was constructed. After optimization of the SIV gag-pol expression plasmid, a minimal SIV vector, which contained only SIV sequences present on the multiply spliced nef transcript, could still be produced at titers of 2 x 10(5) infectious units/ml. Growth-arrested cells could be transduced with this vector even if vif, vpr, vpx, and nef had been deleted from the packaging construct and the vector.

Animals↗
PubMed2000

Chemical and biochemical composition of caviar from different sturgeon species and origins.

The chemical and biochemical composition of caviar in 22 specimens of wild caught and of 2 farmed animals were measured. The results include grain size, protein and fat content, fatty acid composition of triglycerides and phospholipids, as well as the concentrations of relevant heavy metals and chlorinated hydrocarbons. The average protein content varied between 26.2 and 31.1% (wet weight) and fat from 10.9 to 19.4% (wet weight) with lowest values for caviar from farmed sturgeon. The triglycerides and phospholipids contained more n-3 fatty acids, especially eicosapentaenoic and docosahexaenoic acid than n-6 fatty acids. The copper and zinc concentrations varied between 1.20 and 1.69 and 10.3 and 12.4 mg/kg (wet weight), respectively. These values reflect the elevated requirement of sturgeons for these components. Lead content varied between 0.06 and 0.15 mg/kg (wet weight). The cadmium concentrations were less than 5 micrograms/kg (wet weight) leading to the conclusion that no accumulation took place in the eggs. The concentrations of sigma DDT and sigma PCB were extremely high in caviar from Huso huso compared to the samples of the other species thus reflecting the different food habits leading to increased bio-accumulation.

Animals↗
PubMed2000

[PSA rise after radical prostatectomy].

Approximately 18 % of patients will experience PSA failure only after radical prostatectomy. The rate of clinical (local or systemic) recurrence is in the same range. Clinical recurrence is accompanied by an increasing PSA in almost all cases. Altogether, the 10-year risk of PSA recurrence after radical prostatectomy for clinically localized prostate cancer is about 35 %. PSA relapse precedes the development of metastases by a median time of 8 years. The median survival after the manifestation of metastases is about 4-5 years. To differentiate the reasons of PSA failure, recurrence-free interval, Gleason score and PSA doubling time deliver important information. Patients with a high probability of isolated local failure (PSA relapse later than two years after radical prostatectomy) should undergo a biopsy, if a local radiotherapy is considered. The results of current clinical trials are eagerly awaited to answer the question weather immediate, delayed or intermittent hormonal therapy offer best results in individual cases.

Biomarkers, Tumor↗
PubMed2000

[Early detection of prostatic carcinoma in urologic practice with digital rectal examination and prostate-specific antigen. Early Detection Project Group].

For the early detection of prostate cancer, a patient should undergo digital rectal examination (DRE) and PSA investigation. Follow-up of increased PSA levels detects nearly 80% of cancers. Positive predictive value of suspicious DRE and PSA is about 50%. Whereas in the first evaluation of this case-finding trial about 70% of the patients had organ-confined cancers, nearly all of the detected cancers in the follow-up investigation were organ confined. The increased number of organ-confined cancers detected in early periodical examinations can lead to a reduction of mortality and morbidity from prostate cancer.

Adult↗
PubMed2000

Lectin-mediated bioadhesion: preparation, stability and caco-2 binding of wheat germ agglutinin-functionalized Poly(D,L-lactic-co-glycolic acid)-microspheres.

To take advantage of the cytoadhesive characteristics of Wheat germ agglutinin (WGA) for improved particulate drug delivery, the interaction between WGA-grafted poly(D,L-lactic-co-glycolic acid)-microspheres and Caco-2 monolayers was investigated using bovine serum albumin (BSA) or glycine coated microspheres as a control. Covalent immobilization of WGA by the carbodiimide/N-hydroxysuccinimide-method on 4 microm microspheres yielded a surface density of 9.67+/-1.21x10(6) molecules/particle, whereas 0.22+/-0.04x10(6) WGA-molecules were bound by physical adsorption. After storage for 21 days in HEPES-buffer and treatment of the particles with 5 M urea, 86% of covalently linked lectin was still attached to the particles. At 4 degrees C the Caco-2 binding rate of both, WGA- and BSA-modified particles increased with addition of increasing numbers of particles until saturation was reached at 38150+/-1740 (WGA) or 12066+/-1195 (BSA) microspheres bound/mm(2) Caco-2 monolayer. Inhibition of Caco-2 binding of WGA-functionalized microspheres by chitotriose indicated for specificity of the interaction. As observed by confocal laser scanning microscopy, the fluorescein-loading of the particles was accumulated intracellularly after incubation of Caco-2 monolayers with WGA-modified microspheres contrary to glycine-grafted microspheres. Additionally, in case of WGA-functionalized microspheres the amount of cell associated fluorescein was 200-fold higher than that of the free solution. In conclusion, WGA-modified microspheres are expected to enhance intestinal transport of incorporated drugs due to cytoadhesion provided by the lectin coating.

Animals↗