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Biomedical subjects

Torsten Schmidt

Publications and source records attributed to Torsten Schmidt.

12 recordsLinked to original sources
PubMed2005

A new targeting approach for breast cancer gene therapy using the heparanase promoter.

Gene therapy with adenoviral (Ad) vectors is a promising new approach in the treatment of cancer. Strategies to restrict adenoviral-mediated transgene expression are important to avoid gene transfer into normal cells. Heparanase (HPR) is overexpressed in breast cancer but downregulated in differentiated normal tissue. Expression of the HPR gene was evaluated in breast cancer cells. Biodistribution and liver tropism was evaluated in a mouse model. HPR is highly expressed in breast cancer tissue. The HPR promoter retained its fidelity in an adenovirus context and was activated in breast cancer cells but showed low activity in normal breast cells and the murine liver. We conclude that the HPR pathway is a promising target for the development of breast cancer directed gene therapy strategies.

Adenoviridae↗
PubMed2005

Is there an association between septate uterus and endometriosis?

BACKGROUND: The question of whether Müllerian anomalies are significantly more often combined with endometriosis is a controversially discussed problem. Some publications described this association in patients with obstructive but not non-obstructive Müllerian anomalies or controls without Müllerian anomalies. The aim of this study was to evaluate the incidence of endometriosis in patients with a septate uterus as a non-obstructive form of Müllerian anomalies. METHODS: In a retrospective study, we evaluated 120 patients (29.4 +/- 4.7 years; mean +/- SD) with a septate uterus. The control group consisted of 486 consecutive infertile patients (30.8 +/- 6.3 years) with a normal hysteroscopy and laparoscopy. RESULTS: The incidence of dysmenorrhoea was comparable in both groups, but the incidence of endometriosis was significantly higher in patients with a septate uterus (25.8 versus 15.2%, P = 0.006). CONCLUSION: Our results suggest a higher incidence of endometriosis in patients with a septate uterus. If it can be confirmed by others, the initial finding of a septate uterus in infertile patients should be followed by a combined hysteroscopy and laparoscopy.

Adult↗
PubMed2004

Animal-free production of ccc-supercoiled plasmids for research and clinical applications.

The topological structure of plasmid DNA can be characterized by capillary gel electrophoresis (CGE analysis)-an important tool for quality control and stability assessments in DNA storage or application. Hence, a large-scale manufacturing process was developed that allows the removal of undesired open circular (oc) or linear plasmid topologies, bacterial genomic DNA, RNA, proteins as well as lipopolysaccharides (endotoxins) and results in obtaining supercoiled (covalently closed circular, ccc) plasmid DNA in a pure form without using any animal-derived substances. Using CGE, the development and in-line monitoring for pharmaceutical plasmid production starting from fermentation control throughout the whole manufacturing process including the formulated and filled product can be performed the first time in a way conforming to good manufacturing practices (GMP). Plasmid stability data were obtained from analysis of shear effects influencing the plasmid quality in DNA drug delivery formulation and application (e.g. gene gun or jet injection). The physical stability of plasmid DNA is for the first time evaluated in DNA storage experiments on the level of different plasmid forms.

DNA, Superhelical↗
PubMed2004

High apoptotic index correlates to p21 and p27 expression indicating a favorable outcome of primary breast cancer patients, but lacking prognostic significance in multivariate analysis.

This study was performed in order to investigate the role of the apoptotic index (AI) as a prediction parameter for the prognosis of patients with primary breast cancer. AI was determined by DNA fragmentation on 298 primary breast cancer samples and compared to clinically established breast cancer parameters. Additionally, we determined the expression of functional parameters including proliferating cell nuclear antigen, p21waf and p27kip by immunohistochemistry. The mean AI was found to be 11.9% (range, 0-90%). 189 tumors (63.4%) were negative for apoptosis, while 109 tissue samples (36.6%) were apoptotic with >5% positive cells. Using univariate analysis (chi2 test), the AI did not show any significant correlation to one of the established prognostic parameters of primary breast cancer (p > 0.05). In contrast, we found a significant positive correlation to the expression of the cell cycle inhibitors p21waf (p = 0.04) and p27kip (p = 0.024). During the clinical follow-up (median observation time for disease-free survival 87 months), several clinically established prognostic parameters including menopausal status, nodal status, tumor size, tumor grade, and hormone receptor expression could be confirmed and were analyzed with respect to the AI in the tumor. Furthermore, AI displayed a significant positive correlation to disease-free survival using Kaplan-Meier survival analysis (log-rank test, p = 0.04). However, AI lost its prognostic significance in multivariate analysis based on the Cox proportional hazard model (relative risk 0.8, confidence interval 0.52-1.33, p = 0.44). Our data indicate that high apoptotic rates in cancer tissues are indicative of a favorable patient outcome. However, the AI was not an independent factor. The study provides indirect evidence that this process may involve cell cycle inhibitors physiologically.

Apoptosis↗
PubMed2003

Production of supercoiled multimeric plasmid DNA for biopharmaceutical application.

Production of nucleic acids as an active pharmaceutical ingredient (API) in gene therapy and genetic vaccination is gaining more and more importance. Non-viral vectors like plasmid DNA are currently investigated in various clinical trials. Supercoiled multimeric plasmids are of particular interest for pharmaceutical purpose because they contain multiple copies of a therapeutic gene and can therefore be more efficient vectors. A process for the preparation of Escherichia coli strains replicating dimers, trimers, and tetramers of a 4.6 kb plasmid is presented. Cultivation of these clones on semi-defined glycerol medium in a 7 l bioreactor shows structural stability of dimers and trimers during the whole cultivation process. Plasmid concentrations and selectivities are compared to the corresponding cultivation with the plasmid monomer. Cultivation of the tetramer replicating strain shows a disintegration of the plasmid multimer and reconstitution of the monomer and smaller multimers.

Biopharmaceutics↗
PubMed2003

Stability analysis for long-term storage of naked DNA: impact on nonviral in vivo gene transfer.

The transfer of naked DNA is gaining growing acceptance for nonviral gene therapy. Integrity and stability of the DNA used in nonviral gene therapy is known to be decisive for efficacy of gene transfer and transgene expression. Thus, preclinical and clinical studies require the safe storage of DNA preparations to ensure defined quality and conformation. To evaluate the influence of potentially destructive processes on plasmid DNA associated with long-term storage, capillary gel electrophoresis (CGE) analysis of the LacZ-expressing pCMVbeta plasmid over a period of 13 months was performed. The CGE analysis revealed that stable storage conditions at -80 degrees C prevent an increase in open circular (oc) plasmid, preserving the covalently closed circular (ccc) form, which is sought for efficient gene transfer. By contrast, long-term storage of plasmid DNA at 4 degrees C leads to the rapid decline of the ccc form and the increase of oc and linear DNA molecules. The use of naked DNA stored for 1, 2, or 13 months at -80 degrees C showed similar in vivo transfer efficiencies by jet-injection. Therefore, analysis of plasmids by CGE allows the reliable determination of integrity and distribution of the topology of the DNA by quantitative means.

Animals↗
PubMed2003

Minihysteroscopy as routine diagnostic procedure in women with primary infertility.

STUDY OBJECTIVE: To evaluate the importance of routine minihysteroscopy in the diagnosis of primary infertility. DESIGN: Retrospective study (Canadian Task Force classification II-2). SETTING: Endoscopic center at a university hospital. PATIENTS: Three hundred seventy-nine patients with primary infertility. INTERVENTION: Diagnostic minihysteroscopy without anesthesia or sedation. MEASUREMENTS AND MAIN RESULTS: Hysteroscopy was normal in 337 patients (89.9%). In 38 patients (10.1%) an intrauterine pathology was found: 26 intrauterine adhesions, 12 cases of uterus subseptus. The procedure could not be completed in four women. CONCLUSION: Minihysteroscopy should become a routine diagnostic procedure in women with primary infertility, even those with no suspected intrauterine pathology or other risk factors.

Adult↗
PubMed2003

Hematological side-effect profiles of individualized chemotherapy regimen for recurrent ovarian cancer.

The long-term results for patients with recurrent ovarian cancer (ROC) are poor. There is a need to optimize treatment strategies to improve outcome by avoiding ineffective regimens which are often associated with exacerbated side-effects. Individualized chemotherapy regimens guided by a chemosensitivity assay (ATP-tumor chemosensitivity assay) have already been used successfully to direct chemotherapy. Taking the results of this assay into account, application of drug combinations appears more advisable. Here we present a systematic evaluation of toxicities seen with individualized chemotherapy for ROC. A total of 62 patients who received 314 cycles of antineoplastic therapies were evaluated. Three single agents (topotecan, paclitaxel and gemcitabine) and five combinations (cisplatin/gemcitabine, carbopatin/gemcitabine, gemcitabine/treosulfan, mitoxantrone/paclitaxel and carboplatin/paclitaxel) were examined. With respect to myelotoxicity, most single agents except topotecan revealed favorable results in comparison to drug combinations. However, this observation lacks statistical significance. Generally, severe myelosuppression was rare. The highest incidence of leukopenia was seen in regimens with mitoxantrone/paclitaxel or gemcitabine/treosulfan, respectively. Thrombocytopenia accompanied most commonly a topotecan therapy. In the present study combination regimens tend to be more toxic than monotherapies. When response rates are comparable, empirically chosen treatment combination therapies should only be practiced in carefully planned clinical studies.

Adenosine Triphosphate↗
PubMed2002

Implantation despite an extensive endometrial defect after hysteroscopic resection of symptom-free residual trophoblastic tissue 15 months after cesarean section.

Successful implantation occurred after embryo transfer in the presence of an extensive endometrial defect after hysteroscopic resection of residual trophoblastic tissue 15 months after cesarean section. At the end of hysteroscopic surgery the anterior uterine wall seemed smooth, although ultimately no endometrium was left in that part and in parts of the fundus. Thus implantation is possible even with extensive endometrial defects. Interesting facts in this case were, first, the long symptom-free period with residual trophoblastic tissue in the uterus, and, second, successful implantation, pregnancy, and delivery despite at least 30% of endometrial surface being irreversibly destroyed. We suggest hysteroscopic resection as the method of choice for exact and minimally traumatic removal of especially older residual trophoblastic tissue.

Adult↗
PubMed2002

Is it possible to recommend an "optimal" postoperative management after hysteroscopic metroplasty? A retrospective study with 52 infertile patients showing a septate uterus.

BACKGROUND: The aim of the retrospective study was to evaluate the "optimal" postoperative management after hysteroscopic metroplasty. METHODS. FIFTY-TWO: infertile patients with a septate uterus were included. Hysteroscopic metroplasty was performed using electrocautery (dissection needle) with postoperative cyclical hormone replacement therapy (HRT) + intrauterine device (IUD) insertion for 3 months (Group 1, n = 22), or HRT alone for 3 months (Group 2, n = 13), or without postoperative therapy (Group 3, n = 17). RESULTS: During a median follow-up of 21+/-16.9 months 40.9% in Group 1, 53.8% in Group 2 and 41.2% in Group 3 (p > 0.05) resulted in ongoing pregnancies. The rates of delivery at term were 53.3%, 64.4% and 88.9%, respectively. CONCLUSIONS: A postoperative 3-months HRT + IUD insertion or a HRT alone after hysteroscopic metroplasty are not necessary.

Adult↗
PubMed2002

Intratumoral low-volume jet-injection for efficient nonviral gene transfer.

Jet-injection has become an applicable technology among other established nonviral delivery systems, such as particle bombardment or in vivo electroporation. The low-volume jet injector employed in this study uses compressed air to inject solutions of 1.5-10 microL containing naked DNA into the desired tissue. The novel design of this prototype makes multiple jet-injections possible. Therefore, repeated jet-injections into one target tissue can be performed easily. This jet-injector hand-held system was used for the direct in vivo gene transfer of plasmid DNA into tumors to achieve efficient expression of reporter genes (beta-galactosidase, green fluorescent protein [GFP]) and of therapeutic genes (TNF-alpha) in different tumor models. The study presented here revealed the key parameters of efficient in vivo jet-injection (jet-injection volume, pressure, jet penetration, DNA stability) to define the optimal conditions for a jet-injection-aided nonviral gene therapy.

Animals↗