Biomedical subjects

Thorsten Fischer

Publications and source records attributed to Thorsten Fischer.

13 recordsLinked to original sources

PubMed2006

The impact of breast cancer awareness and socioeconomic status on willingness to receive breast cancer prevention drugs.

PURPOSE: To find associations between knowledge about risk factors for breast cancer and the socioeconomic status of healthy women, as well as their attitude toward taking chemopreventive drugs. PATIENTS AND METHODS: Between April and September 1999, 7135 healthy women completed questionnaires providing information about their willingness to take chemopreventive drugs. Items in the questionnaire included the sources of the information they had, their estimates of the population and personal lifetime risk, and risk factors for breast cancer. RESULTS: A total of 6597 questionnaires were evaluable. The responders' median age was 44. Fifty-five percent of the women were willing to consider receiving chemopreventive drugs to lower their risk for breast cancer. Participants who estimated the population risk as being very high were more disposed to receive chemoprevention (65.3%), as were women who estimated their own breast cancer risk as being high (74.1%). A family history of breast cancer only had a low impact on willingness to receive chemoprevention. Women with a family history of breast cancer were willing to take chemopreventive agents in 57.2% of cases. The multivariate analysis showed that knowing about risk factors and having a lower educational level were factors positively correlated with willingness to consider chemoprevention. CONCLUSION: These findings emphasize the role of estimations of the risk of breast cancer for patients considering whether to accept chemoprevention treatment. To date, only a few modern models of risk estimation have been evaluated in relation to chemoprevention. There is a need for better integration of professional risk estimations into clinical practice.

Adult↗

PubMed2006

[Reduced serotonin levels in platelet-free plasma of adolescents with externalizing behaviour problems].

OBJECTIVES: A serotonergic dysfunction, in particular a reduced serotonergic neurotransmission in the frontal cortex and limbic brain regions, has been discussed in connection with the aetiology of aggressive and impulsive behaviour. Assessment of the activity in the central serotonergic system in children and adolescents is limited due to its technical complexity and ethical restrictions. Therefore, peripheral serotonergic parameters have been used as a model to obtain deeper insight into central serotonergic functions. The aim of this investigation is to examine the significance of plasma serotonin measurement with regard to behavioural problems in adolescents at risk for psychopathology. METHODS: Within the framework of a prospective longitudinal study of children at risk, serotonin levels in platelet-free blood plasma were measured in a group of n = 10 adolescents aged 15 years with persistent externalizing behaviour (T-score > or = 60 on the "Externalizing Problems" scale of the CBCL) and in a control group of n = 20 mentally undisturbed adolescents. Groups were matched according to age and gender. Externalizing behaviour was assessed by means of a parent questionnaire, the Achenbach Child Behavior Checklist (CBCL). RESULTS: Significantly lower levels of plasma serotonin were found in adolescents with persistent behaviour problems than in the control group. Significant negative correlations between serotonin levels and the CBCL scales "Aggressive Behavior" and "Externalizing Problems" were obtained for the total sample. CONCLUSIONS: Earlier findings that described a serotonergic deficit as a key mechanism in the manifestation of aggressive and antisocial behaviour are confirmed for adolescents at risk taken from a community sample.

Adolescent↗

PubMed2005

Polarization multiplexed write-once-read-many optical data storage in bacteriorhodopsin films.

In polymeric films of bacteriorhodopsin (BR) a photoconversion product, which was named the F620 state, was observed on excitation of the film with 532 nm nanosecond laser pulses. This photoproduct shows a strong nonlinear absorption. Such BR films can be used for write-once-read-many (WORM) optical data storage. We demonstrate that a photoproduct similar or even identical to that obtained with nanosecond pulses is generated on excitation with 532 nm femtosecond pulses. This photoproduct also shows strong anisotropic absorption, which facilitates polarization storage of data. The product is thermally stable and is irretrievable to the initial B state either by photochemical reaction or through a thermal pathway. The experimental results indicate that the product is formed by a two-photon absorption process. Optical WORM storage is demonstrated by use of two polarization states, but more polarization states may be used. The combination of polarization data multiplexing and extremely short recording time in the femtosecond range enables very high data volumes to be stored within a very short time.

Journal Article↗

PubMed2005

Physician-based active cost management of oncological therapies reducing pharmaceutical costs by 83.4% in two years without leaving standard of care.

We report about the 2-year results of a physician-based active cost management model for oncological therapies in a German OB/GYN university clinic. Over 2 years more than 4,000 oncological cycles were prospectively and individually analyzed regarding costs and reimbursement mode. Main aim was reducing costs without lowering cycle number and standard of care. Within two years pharmaceutical costs were reduced by 83.4% or 785,976-EUR. All causes for a previous financial loss were identified and eliminated. Debts were paid back and employment of new staff and investments were possible. With this first active cost management model by and for physicians, oncological therapies can be performed cost covering even in a university clinic. Although developed for optimization of cost coverage of oncological therapies in Germany, this model is universally transferable.

Antineoplastic Agents↗

PubMed2005

Two-photon absorption of bacteriorhodopsin: formation of a red-shifted thermally stable photoproduct F620.

By means of high-intensity 532 nm laser pulses, a photochemical conversion of the initial B(570) state of bacteriorhodopsin (BR) to a stable photoproduct absorbing maximally at approximately 620 nm in BR suspensions and at approximately 610 nm in BR films is induced. This state, which we named F(620), is photochemically further converted to a group of three products with maximal absorptions in the wavelength range from 340 nm to 380 nm, which show identical spectral properties to the so-called P(360) state reported in the literature. The photoconversion from B(570) to F(620) is most likely a resonant two-photon absorption induced step. The formation of F(620) and P(360) leads to a distinguished photo-induced permanent optical anisotropy in BR films. The spectral dependence of the photo-induced anisotropy and the anisotropy orientations at the educt (B(570)) and product (F(620)) wavelengths are strong indicators that F(620) is formed in a direct photochemical step from B(570). The chemical nature of the P(360) products probably is that of a retro-retinal containing BR, but the structural characteristics of the F(620) state are still unclear. The photo-induced permanent anisotropy induced by short laser pulses in BR films helps to better understand the photochemical pathways related to this transition, and it is interesting in view of potential applications as this feature is the molecular basis for permanent optical data storage using BR films.

Bacteriorhodopsins↗

PubMed2005

Effect of pregnancy on long-term kidney function in renal transplant recipients treated with cyclosporine and with azathioprine.

In order to investigate the effect of different immunosuppressive regimens and the time interval between transplantation and pregnancy on long-term outcome, we performed a case-control study in pregnant renal allograft recipients. Eighty-one pregnancies of kidney transplanted recipients were identified [cyclosporine (CYA): n = 40; azathioprine (AZA): n = 41]. Controls were matched with respect to important prognostic factors. Posttransplant follow-up was 91.3 +/- 5 months. Graft and patient survival were similar in both groups and there was no apparent effect of immunosuppression. A total of 28 recipients (33%) delivered within 2 years and 6 (8%) subjects within 1 year after transplantation, but these short transplantation-to-pregnancy intervals had no apparent adverse effect on long-term outcome. In contrast to AZA-treated patients, CYA-treated patients experienced an increase in serum creatinine postpartum (1.15 +/- 0.2 mg/dL vs. 1.61 +/- 0.1 mg/dL; p < 0.05). Whole blood CYA levels decreased transiently during pregnancy from 115.9 +/- 8 ng/mL to 80.7 +/- 7 ng/mL leading to a gradual increase in drug dose from 240 +/- 14 mg/day to 324 +/- 21 mg/day (p < 0.05). Following delivery, there was an increase in CYA concentrations to 173 +/- 5.4 ng/mL, requiring rapid dose tapering to baseline of 246 +/- 15 mg/day. Pregnancies in renal recipients do not affect long-term patient and graft survival, independent of the immunosuppression. No detrimental effect of short transplantation-to-pregnancy intervals on long-term graft function was detected.

Adult↗

PubMed2004

Prolongation of pregnancy following eclampsia.

Eclampsia is a serious complication of preeclampsia with high maternal and perinatal mortality and morbidity rates. The recommended management is induction of labour when convulsions are controlled and the women's condition is stabilised. Here, we report about stabilisation after eclampsia followed by prolongation of a preterm pregnancy for 11 days within early gestational weeks.

Adult↗

PubMed2004

Encapsulation of purple membrane patches into polymeric nanofibers by electrospinning.

The formation of beaded nanofibers containing purple membrane (PM) by electrospinning of polymer solutions is reported. Electrospinning is known as a versatile method to produce polymeric fibers with diameters on the nanometer scale. Embedding of particles significantly larger than the fiber diameter is unexpected because a breakdown of the spinning process is expected when microscaled particles in the polymer solution pass the nozzle. Presumably due to the flexibility of PM patches, the embedding of the membrane patches into the fibers becomes possible. Embedding into nanofibers may be an alternative to microencapsulation for biomolecules.

Bacteriorhodopsins↗

PubMed2003

Association of maternal and/or fetal factor V Leiden and G20210A prothrombin mutation with HELLP syndrome and intrauterine growth restriction.

This study was conducted to investigate the association of maternal and/or fetal factor V Leiden (FVL) and G20210A prothrombin mutation with HELLP syndrome. FVL and G20210A prothrombin mutation were determined using PCR. Sixty-three pregnant women, 36 of them diagnosed with HELLP syndrome, were included in the study. Overall, 68 children were born as a result of these pregnancies and blood sampling was possible in 28 out of 39 children from HELLP patients and 25 out of 29 children from the control women. The prevalence of a maternal FVL was elevated 2-fold in HELLP patients compared with the control women [six out of 36 (16.7%) compared with two out of 27 (7.4%); P =0.282]. None of the HELLP patients and only one woman in the control group was found to be positive for the G20210A prothrombin mutation (P =0.251). The fetal carrier frequency was four out of 28 compared with three out of 25 for FVL (P =0.811), and two out of 28 compared with one out of 25 for G20210A prothrombin mutation (P =0.629). Intrauterine growth restriction (IUGR) was significantly higher in fetuses found to be positive for a thrombophilic mutation (P =0.022). IUGR occurred in seven out of ten fetuses with a thrombophilic mutation compared with 11 out of 43 in fetuses without a mutation. The prevalence of FVL, but not of the G20210A prothrombin mutation, seems to be elevated in women with HELLP syndrome. A fetal thrombophilic mutation does not contribute significantly to the clinical features of the HELLP syndrome. Our results demonstrate a fetal contribution to IUGR. Fetal thrombophilic mutations may lead to placental microthrombosis, which consecutively could lead to a disturbed fetoplacental blood flow and thus cause growth restriction.

Adult↗

PubMed2003

Biomolecular optical data storage and data encryption.

The use of bacteriorhodopsin (BR) as an active layer in write-once-read-many optical storage is presented. This novel feature of BR materials may be used on a wide variety of substrates, among them transparent substrates but also paper and plastics. The physical basis of the recording process is polarization-sensitive two-photon absorption. As an example for this new BR application, an identification card equipped with an optical recording strip is presented, which has a capacity of about 1 MB of data. The recording density currently used is 125 kB/cm2, which is far from the optical limits but allows operation with cheap terminals using plastic optics. In the examples given, data are stored in blocks of 10 kB each. A special optical encryption procedure allows the stored data to be protected from unauthorized reading. The molecular basis of this property is again the polarization-sensitive recording mechanism. The unique combination of optical storage, photochromism, and traceability of the BR material is combined on the single-molecule level. BR introduces a new quality of storage capability for applications with increased security and anticounterfeiting requirements.

Bacteriorhodopsins↗

PubMedDate not supplied

Breast ductoscopy with a 0.55-mm mini-endoscope for direct visualization of intraductal lesions.

Standard radiologic examinations of breast duct lesions can give only indirect information. Mini-endoscopy with a breast ductoscope of only 0.55 mm offers direct visualization of the lesion and helps in the decision to perform or avoid exploratory breast tissue resection. We used a LaDuScope (PolyDiagnost, Pfaffenhofen, Germany) with a 0.55- or 0.95-mm outer diameter and a 75-mm working length from October 2003 through July 2004 on 11 women (average age of 48.3 years [range 36-69 years]) with suspicious nipple discharge. The optics have zero-degree direct view, 70-degree field vision, and 3000 or 6000 pixel resolution. Breast ducts and walls could be easily inspected; and irrigation of breast ducts, aspiration, and use of cytology brush were possible under visual control. We had no intraoperative or postoperative complications. The new procedure of mini-ductoscopy is feasible, safe, and helpful as an additional ambulatory diagnostic method for visual inspection of breast ducts. This instrument demonstrates the latest advances of technology and a trend toward less-invasive diagnostics for breast duct lesions.

Adult↗

PubMedDate not supplied

Development of a thinner and more flexible type of minihysteroscope with a controlled 90-degree bendable tip for vision-guided endometrium biopsy.

STUDY OBJECTIVE: Evaluation of the uterine cavity is limited with rigid 5-mm hysteroscopes because of the need for cervical dilatation, reduced movements inside the uterus, and no option for vision-guided biopsy. In cooperation with PolyDiagnost GmbH, Pfaffenhofen, Germany, a new type of flexible minihysteroscope with bendable tip was developed and evaluated. DESIGN: Prospective and parallel observational interindividual evaluation of flexible minihysteroscope and standard hysteroscope for diagnostic hysteroscopy (Canadian Task Force classification II-3). SETTING: Obstetrics and gynecology department of a university clinic. PATIENTS: Nine women, average age 65.0 years (range 46-89 years), with indications for diagnostic hysteroscopy. INTERVENTIONS: After defining requirements, a novel, thinner, and more flexible minihysteroscope, 18-cm long with a 2.67-mm outer diameter, was developed with straight zero-degree scope, 70-degree vision field, and 6000-pixel resolution. Two working channels, 1.2 mm and 0.55 mm, allow suction-irrigation and introduction of a 1.0-mm biopsy forceps or cytology brush. The tip of the instrument is 90-degree stageless bendable to both sides. Diagnostic hysteroscopy was performed with flexible minihysteroscope followed by standard rigid hysteroscopy to verify results. MEASUREMENTS AND MAIN RESULTS: From July 2003 through March 2004, both procedures were performed in nine patients with identical visual and histologic results. No complications occurred. No cervix-dilating instruments were necessary for introduction of the flexible minihysteroscope. Visualization of the entire uterine cavity is improved with the flexible scope because a bendable tip allows better peripheral vision (e.g., of the openings of the tubes). However, movement of the tip should be performed carefully due to potential risk of uterine perforation. CONCLUSION: This new flexible minihysteroscope is less invasive compared with standard rigid hysteroscopy, which supports performance of ambulatory hysteroscopy and makes increased movements and vision-guided biopsy inside the uterine cavity possible.

Aged↗

PubMedDate not supplied

Three-dimensional model for gas flow, resistance, and leakage-dependent nominal pressure maintenance of different laparoscopic insufflators.

STUDY OBJECTIVE: To compare laparoscopic insufflators with different insufflation characteristics and evaluate the effects of resistance and leakage on maintenance of nominal pressure. DESIGN: Prospective study (Canadian Task Force classification II-2). SETTING: Laboratory of university clinic. INTERVENTIONS: Measurement in an abdomen box model of insufflator response to different resistance and leakage combinations during steady state while attempting to maintain a nominal set pressure of 12 mm Hg. MEASUREMENTS AND MAIN RESULTS: An abdomen box model for laboratory measurements was designed with differing entrance and exit diameters simulated by hole disks of 0.5 mm to 7.6 mm. With a computer-based data-acquisition model, five insufflators (Olympus 9L and 16L, Storz 10L and 30L, HiTec 16L) were evaluated with 150 disk combinations. Average abdominal box pressures were recorded in three-dimensional (3-D) profiles showing different nominal pressure maintenance response for all insufflators regarding the resistance and leakage combination, maximum flow performance, and insufflation principle of the device. Average abdomen model box pressure can increase up to 26.57 mm Hg at 12 mm Hg nominal pressure setting (+121.4%). Insufflators with high flow rates (Storz 30L) tend to compensate leakage better but with the risk of higher intraabdominal pressure peaks. Insufflators with low-pressure principle (HiTec 16L) have limited pressure compensation but are safer for the patient. CONCLUSIONS: Nominal pressure maintenance of insufflators is mainly dependent on flow resistance and leakage rate and less on potential insufflator flow capacity. With this 3-D model, the nominal pressure maintenance of different insufflators can be described for the first time regarding these main factors.

Abdominal Cavity↗