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Biomedical subjects

M Lein

Publications and source records attributed to M Lein.

At least 19 recordsLinked to original sources
PubMed2006

Fast-track surgery in laparoscopic radical prostatectomy: basic principles.

Fast-track surgery describes innovative treatment concepts ensuring a faster convalescence phase. The aim of this study was to allow hospital discharge 3 days after surgery without additional complications in patients receiving LRPE for localized prostate cancer. Twenty-five patients each were randomized in the study groups to verify if a fast-track regimen could be transferred into clinical routine. The perioperative data, early complications, hospital stay as well as readmission rate were analyzed. The mean postoperative stay was 3.6 days in the fast-track group versus 6.7 days in the conventional group. The overall complications were significantly less in the fast-track procedure. The readmission rate was low and not significant. Patients receiving an LRPE benefit from a suitable fast-track concept. The postoperative hospital stay could be shortened nearly by half with a significantly decreased overall complication rate. Thus, fast-track concepts might contribute to saving resources in the long term. However, more evidence based on larger prospective trials is needed to achieve optimal quality of life for patients perioperatively.

Aged↗
PubMed2006

Treatment of varicocele with reference to age: a retrospective comparison of three minimally invasive procedures.

BACKGROUND: This study investigated whether the therapeutic efficacy and morbidity of three minimally invasive techniques for varicocele correction--laparoscopic varicocelectomy (LV), antegrade sclerotherapy (AS), and retrograde embolization (RE)--differed between children and adults. METHODS: During a 10-year period, 356 procedures for varicocele correction, including 122 cases of LV, 108 cases of AS, and 126 cases of RE, were performed for 314 patients at our institution. Of these patients, 223 were 19 years of age or younger (group 1), and 133 were older than 19 years (group 2). Diagnosis and postoperative results were established clinically and with the use of Doppler ultrasonography. The failure rates and complications for each procedure were retrospectively evaluated and compared between the two age groups. RESULTS: The median follow-up period was 69 months (range, 6-122 months). For 25 patients (19.8%), RE was not feasible for technical reasons. In both groups, LV had a lower failure rate than AS or RE, but the difference between LV and AS was not significant in group 1 (7.7(% vs 11.9%; p > 0.5). Also in group 1, AS was associated with fewer complications than LV 1 (4.5% vs 15.4%; p < 0.05). In group 2, LV was significantly more effective in correcting varicoceles than the other two techniques (p < 0.01). In this group, the complication rates for all three procedures did not differ significantly (p > 0.05). CONCLUSIONS: In our experience, LV was more effective than AS or RE in correcting varicoceles. For children and adolescents, AS may be more indicated because of the slightly lower complication rate and similar recurrence rates, as compared with LV, for this age group. The higher incidence of postoperative hydrocele formation after LV warrants more refined techniques such as the lymphatic-sparing approach.

Adolescent↗
PubMed2006

Enhanced recollisions for antisymmetric molecular orbitals in intense laser fields.

The peculiarities of antisymmetric molecular orbitals are investigated in very intense linearly polarized laser pulses. For this purpose, the ionization-recollision quantum dynamics is evaluated theoretically beyond the dipole approximation. As opposed to the usual situation, the laser magnetic field component is found to strongly enhance recollision probabilities for particularly oriented antisymmetric molecular orbitals. Harmonic generation and related processes are thus allowed at high laser intensities without the common limitations by the laser magnetic field.

Journal Article↗
PubMed2006

Probing proton dynamics in molecules on an attosecond time scale.

We demonstrate a technique that uses high-order harmonic generation in molecules to probe nuclear dynamics and structural rearrangement on a subfemtosecond time scale. The chirped nature of the electron wavepacket produced by laser ionization in a strong field gives rise to a similar chirp in the photons emitted upon electron-ion recombination. Use of this chirp in the emitted light allows information about nuclear dynamics to be gained with 100-attosecond temporal resolution, from excitation by an 8-femtosecond pulse, in a single laser shot. Measurements on molecular hydrogen and deuterium agreed well with calculations of ultrafast nuclear dynamics in the H2+ molecule, confirming the validity of the method. We then measured harmonic spectra from CH4 and CD4 to demonstrate a few-femtosecond time scale for the onset of proton rearrangement in methane upon ionization.

Journal Article↗
PubMed2006

Body size and weight as predisposing factors in varicocele.

OBJECTIVE: The literature regarding the constitutional type of children and adolescents with varicocele is inconsistent. The aim of this investigation was to examine a possible influence of weight, height and body mass index (BMI) on the formation of varicoceles during childhood and adolescence. MATERIAL AND METHODS: In a retrospective data analysis, 193 Caucasian children and adolescents aged 9-19 years (mean age 14.7 years) with left-sided varicocele grade 2-3 were studied. The weight, height and BMI of the subjects were compared with the age-correlated normal values currently accepted in Germany. Additionally, the familial disposition for varicocele and the occurrence of relevant concurrent diseases were considered. RESULTS: In the group of patients examined, the mean percentiles of weight (57th) and height (58th) were significantly above and the mean BMI percentile (42th) was significantly below the age-correlated 50th percentile for the normal population (p=0.019, 0.005 and 0.002). In our case material, 12.2% of all brothers of the patients had varicoceles. CONCLUSIONS: The results of this investigation suggest a correlation between physical appearance and the formation of a varicocele during childhood or adolescence. We were able to demonstrate that patients with varicocele were heavier and taller than an age-correlated normal population, but had a distinctly lower BMI. Further studies are needed to verify whether this rather athletic habitus, together with the postulated difference in muscle:fat ratio, represents an important etiologic factor for varicocele formation.

Adult↗
PubMed2005

[Clinical pathway "laparoscopic prostatectomy". Analysis of anesthesiological procedures in a randomized study].

METHODS: In this study we investigated the anesthesiological module of a clinical pathway. We chose the pathway of "laparoscopic prostatectomy" as an example for time-consuming minimally invasive surgery and 40 patients were randomly assigned to 2 groups receiving either total intravenous anesthesia (TIVA) using propofol/ remifentanil or balanced minimal flow anesthesia using desflurane/ remifentanil. During this module the indicators of quality such as vigilance, pain, postoperative nausea and vomiting (PONV) and mobilization were measured. Costs were evaluated and analyzed by a bottom-up procedure. RESULTS: There were no anesthesia-related deviations from clinical pathways and both forms of anesthesia management were equally well tolerated by the patients. No significant difference was observed regarding hemodynamic measurements or PONV. The patients in the desflurane/ remifentanil group recovered more rapidly (p=0.037) and had more pain. The amount of analgesic agents given immediately following anesthesia was significantly higher than in the TIVA group (p=0.017). The median anesthesia costs per minute for laparoscopic prostatectomy in the propofol group were 2.79 EUR (minimum cost 2.41 EUR, maximum cost 3.21 EUR) and in the desflurane group 2.68 EUR (minimum cost 2.45 EUR, maximum cost 3.39 EUR). The total anesthesia costs for both groups were within the proceeds matrix range for diagnosis-related groups (DRG). However, the cost analysis for medication was slightly higher than the proceeds matrix range for DRGs. CONCLUSION: Both forms of anesthesia can be implemented for time-consuming surgical procedures and allow a cost-effective anesthesia management. Anesthesiological procedures must go hand-in-hand with the type of anesthesia selected. The prophylactic use of analgetics for desflurane/ remifentanil anesthesia should be given earlier and in higher doses than in propofol/ remifentanil anesthesia. The prophylactic use of antiemetics following laparoscopic procedures of long duration is indicated. Optimizing anesthesiological procedures could lead to a continuous improvement in the quality of therapeutic pathways.

Aged↗
PubMed2005

Laparoscopic donor nephrectomy.

Laparoscopic live donor nephrectomy (LDN) has removed disincentives of potential donors and may bear the potential to increase kidney donation. Multiple modifications have been made to abbreviate the learning curve while at the same time guarantee the highest possible level of medical quality for donor and recipient. We reviewed the literature for the evolution of the different LDN techniques and their impact on donor, graft and operating surgeon, including the subtleties of different surgical accesses, vessel handling and organ extraction. We performed a literature search (PubMed, DIMDI, medline) to evaluate the development of the LDN techniques from 1995 to 2003. Today more than 200 centres worldwide perform LDN. Hand-assistance has led to a spread of LDN. Studies comparing open and hand-assisted LDN show a reduction of operating and warm ischaemia times for the hand-assisted LDN. Different surgical access sites (trans- or retroperitoneal), different vessel dissection approaches, donor organ delivery techniques, delivery sites and variations of hand-assistance techniques reflect the evolution of LDN. Proper techniques and their combination for the consecutive surgical steps minimize both warm ischaemia time and operating time while offering the donor a safe minimally invasive laparoscopic procedure. LDN has breathed new life into the moribund field of living kidney donation. Within a few years LDN could become the standard approach in living kidney donation. Surgeons working in this field must be trained thoroughly and well acquainted with the subtleties of the different LDN techniques and their respective advantages and disadvantages.

Journal Article↗
PubMed2003

[An artificial neural network as a tool in risk evaluation of prostate cancer. Indication for biopsy with the PSA range of 2-20 microg/l].

In this prospective study covering 5.5 years we evaluated the diagnostic power of an artificial neural network (ANN) based on PSA, %fPSA, and clinical data in the PSA range 2-20 microg/l as prostate biopsy indicator. A total of 944 patients with prostate cancer or benign hyperplasia (BPH) were analyzed. The calculation of the individual patient's risk before prostate biopsy was performed at the 90% and 95% specificity and sensitivity levels within the PSA ranges 2-4, 4.1-10, and 10.1-20 microg/l. For the low PSA range 2-4 microg/l, we recommend a first time biopsy at an ANN specificity level of 95%. For PSA range 4.1-10 microg/l, we recommend a first time biopsy at an ANN sensitivity level of 95%. A rebiopsy at the PSA range 10.1-20 micro g/l should be performed based on a 95% sensitivity level. The use of an ANN at PSA 2-20 microg/l enhances the specificity and sensitivity of %fPSA by 9-39%. The application of an ANN based on %fPSA and clinical data improves the diagnostic performance compared to %fPSA only.

Adult↗
PubMed2002

Role of the intramolecular phase in high-harmonic generation.

We study numerically the generation of high-order harmonics by two-center molecules for arbitrary angles between the molecular axis and the laser polarization axis. For fixed angle, the harmonic spectrum exhibits a minimum at a frequency which is independent of the laser parameters. The amplitude of each harmonic is strongly angle dependent, and a pronounced minimum is found at the same angle where a sudden jump in the harmonic phase occurs. By calculating the spatial dependence of the harmonic amplitudes and phases, we are able to explain these effects in terms of interfering contributions from various regions within the molecule.

Journal Article↗
PubMed2002

The novel synthetic inhibitor of matrix metalloproteinases Ro 28-2653 induces apoptosis in Dunning tumor cells.

The effect of synthetic inhibitors of matrix metalloproteinases (MMP) has been shown against a variety of tumors in preclinical models. Ro 28-2653, a novel synthetic MMP inhibitor, is able to reduce tumor growth in orthotopic prostatic cancer in rats (R3327 Dunning tumor). However, at present this inhibitory mechanism in tumor inhibition in vivo can only be partly explained by the inhibition of the catalytic activity of MMPs overexpressed in cancereous tissue. Using the flow cytometric method, we have investigated the effect of various concentrations of Ro 28-2653 on the Dunning tumor cells with regard to the staining of F-actin and DNA as markers of apoptosis. In combination with fluorescence microscopy we detected the loss of F-actin and the degradation of internucleosomal DNA. This effect of Ro 28-2653 on apoptosis was dose- and time-dependent increasing with concentration between 10 and 100 microg/ml as well as with time of treatment between 24 and 48 h.

Actins↗
PubMed2001

Iron bispentazole Fe(eta5-N5)2, a theoretically predicted high-energy compound: structure, bonding analysis, metal-ligand bond strength and a comparison with the isoelectronic ferrocene.

Quantum-chemical calculations with gradient-corrected (B3LYP) density functional theory have been carried out for iron bispentazole and ferrocene. The calculations predict that Fe(eta5-N5)2 is a strongly bonded complex which has D5d symmetry. The theoretically predicted total bond energy that yields Fe in the 5D ground state and two pentazole ligands is Do = 109.0 kcal mol(-1), which is only 29 kcal mol(-1) less than the calculated bond energy of ferrocene (Do = 138.0 kcal mol(-1); experimental: 158 +/- 2 kcal mol(-1)). The compound Fe(eta5-N5)2 is 260.5 kcal mol(-1) higher in energy than the experimentally known isomer Fe(N2)5, but the bond energy of the latter (Do = 33.7 kcal mol(-1)) is much less. The energy decomposition analyses of Fe(eta5-N5)2 and ferrocene show that the two compounds have similar bonding situations. The metal-ligand bonds are roughly half ionic and half covalent. The covalent bonding comes mainly from (e1g) eta5-N5- --> Fe2+ pi-donation. The previously suggested MO correlation diagram for ferrocene is nicely recovered by the Kohn-Sham orbitals. The calculated vibrational frequencies and IR intensities are reported.

Journal Article↗
PubMed2001

Molecular forms of prostate-specific antigen in serum with concentrations of total prostate-specific antigen <4 microg/L: are they useful tools for early detection and screening of prostate cancer?

Molecular forms of prostate-specific antigen (PSA) improve the differentiation between benign prostatic hyperplasia (BPH) and prostate cancer (PCa) in men with total PSA concentrations between 4 and 10 microg/l. To evaluate the diagnostic utility of free PSA (fPSA) and complexed PSA forms for identification of men with PCa in the low PSA range of <4 microg/l, total PSA (tPSA), alpha(1)-antichymotrypsin complexed PSA (PSA-ACT) and fPSA (Roche Elecsys [ES] system) as well as tPSA and complexed PSA (cPSA) (Bayer Immuno 1 system) were measured in archival serum samples from 31 untreated patients with PCa, 66 patients with BPH, and 90 men without prostatic disease. The median ratios of fPSA/tPSA, PSA-ACT/tPSA and cPSA/tPSA were significantly different between patients with BPH and PCa (27.2 vs. 19.4%, 64 vs. 88%, 77.2 vs. 88.2%, p < 0.05). No associations between PSA forms and tumor stage and grade were found. Analysis of the receiver operating characteristic curves showed that these ratios could discriminate better between BPH and PCa patients than determination of the analytes tPSA, fPSA, cPSA and PSA-ACT alone. The use of one of the ratios would have eliminated roughly half of the unnecessary biopsies in this study. The ratios should be considered as potential tools to increase the selectivity of PCa detection at low PSA concentration. The ratios fPSA/tPSA and cPSA/tPSA can be determined using commercially available assays so that one of these ratios could be preferred instead of PSA-ACT determination. The ratios could be useful in assessing the risk of PCa in the individual and therefore in deciding on prostate biopsy for final diagnosis.

Aged↗
PubMed2001

Even-harmonic generation due to beyond-Born-Oppenheimer dynamics.

We calculate the harmonic spectrum generated by a model HD molecule in a strong laser pulse. The unequal nuclear masses lead to the emission of even harmonics, i.e., photon frequencies which are even multiples of the laser frequency. The effect does not occur within the Born-Oppenheimer approximation. In the high-frequency region, the even harmonics are almost of the same order of magnitude as the odd ones.

Journal Article↗
PubMed2001

A multicenter clinical trial on the use of alpha1-antichymotrypsin-prostate-specific antigen in prostate cancer diagnosis.

BACKGROUND: The aim was to evaluate the clinical performance of alpha(1)-antichymotrypsin prostate-specific antigen (PSA-ACT) for early diagnosis of prostate cancer (PCa) in a multicenter trial. METHODS: Three hundred sixty-seven white men with PCa and 290 with benign prostatic hyperplasia (BPH) with tPSA concentrations between 2 and 20 microg/L were analyzed. The Elecsys system 2010 (Roche Diagnostics, Germany) was used for determination of total PSA (tPSA) and free PSA (fPSA). The PSA-ACT test was a prototype assay used on the ES system (Roche Diagnostics). RESULTS: The median concentrations of tPSA (PCa: 8.43 microg/L vs. BPH: 6.60 microg/L) and PSA-ACT (8.30 microg/L vs. 6.46 microg/L) were significantly different, respectively. The median ratios of fPSA/tPSA (PCa: 12% vs. BPH: 16%) and PSA-ACT/tPSA (98% vs. 95%) were significantly different. Receiver operating characteristics (ROC) analysis for discrimination between PCa and BPH (tPSA between 2 and 20 microg/L) was performed with 252 matched pairs and showed that the area under the curve (AUC) of the ratio fPSA/tPSA (0.66) was significantly different from tPSA (0.50) and PSA-ACT (0.52). PSA-ACT alone or the ratio PSA-ACT/tPSA (0.56) were not significantly different from tPSA. For tPSA between 4 and 10 microg/L (n = 145 pairs), the AUC of the ratio fPSA/tPSA (0.65) was significantly higher than tPSA (0.50) and PSA-ACT (0.54). Significant differences between tPSA and PSA-ACT or PSA-ACT/tPSA (0.56) were not found. CONCLUSIONS: The determination of PSA-ACT as well as the PSA-ACT/tPSA ratio did not improve the diagnostic impact in patients undergoing evaluation for PCa compared to fPSA/tPSA ratio.

Adult↗
PubMed2001

Receiver-operating characteristic as a tool for evaluating the diagnostic performance of prostate-specific antigen and its molecular forms--What has to be considered?

BACKGROUND: Receiver-operating characteristic (ROC) analysis is often applied as evaluation tool to compare the diagnostic validity of laboratory tests. The aim of this study was to draw attention to preconditions which should be taken into account when ROC analysis is used to assess the diagnostic performance of total prostate-specific antigen (tPSA) and its molecular forms in differential diagnosis between prostate cancer and benign prostatic hyperplasia (BPH). METHODS: Using a standard software (GraphROC for Windows), ROC analyses were performed and the areas under the curves were calculated for four hypothetical pairs of groups. Every group included 40 patients with prostate cancer and with BPH showing different tPSA concentrations (range of 2-10 microg, but similar free-to-total PSA ratios (fPSA%). RESULTS: The area under the fPSA% ROC curve showed the highest value, whereas the areas under the tPSA ROC curves were dependent on the distributions of tPSA concentrations in the patients. The ability of fPSA% to improve the differential diagnosis between prostate cancer and BPH in comparison to tPSA was not furthermore evident, if the prostate cancer group included more patients with higher tPSA concentrations than the BPH group. CONCLUSIONS: When the diagnostic performance of tPSA and its derivatives like molecular forms in patients with prostate cancer and BPH should be compared by ROC analysis, a matching procedure is recommended prior to ROC analysis to compensate the effect of possible unequal tPSA distributions in both groups. Each BPH (or PCa) patient should be matched with a PCa (or BPH) patient with nearest tPSA concentration so that an optimum of overlapping tPSA concentrations in both groups can be achieved.

Diagnosis, Differential↗
PubMed2001

Blood specimen collection methods influence the concentration and the diagnostic validity of matrix metalloproteinase 9 in blood.

BACKGROUND: Matrix metalloproteinases (MMP) in blood are promising new diagnostic tools. It was shown that the blood sampling process resulted in different blood concentrations of MMPs. To clarify whether the sampling process also influences the diagnostic validity of MMPs, MMP-9 measurements were performed in plasma and serum samples of patients with prostate carcinoma and renal cell cancer. METHODS: MMP-9 ELISAs were performed in samples of heparin plasma and serum collected in blood tubes with and without clot accelerator. Measurements were undertaken in 78 healthy persons, 33 patients with prostate carcinoma and 33 patients with renal cell carcinoma. RESULTS: MMP-9 showed higher concentrations in serum samples than in heparin plasma and was about threefold higher in serum samples collected in tubes with clot activator than in native serum samples. Both patient groups had lower MMP-9 concentrations in serum, whereas in plasma, patients with renal cell carcinoma had higher, but patients with prostate cancer unchanged MMP-9 concentrations. 13 of 33 patients with renal cell carcinoma had increased MMP-9 plasma values but no patient had increased serum concentrations. CONCLUSIONS: To optimise the diagnostic validity of the MMP-9 in blood, measurements should be performed in heparin plasma but not in serum.

Blood Specimen Collection↗