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M Müller

Publications and source records attributed to M Müller.

At least 181 records · Page 10Linked to original sources
PubMed2002

Lateral versus perpendicular segregation in mixed polymer brushes.

Grafting of incompatible polymers on a substrate prevents macrophase separation and the chains self-assemble laterally. Mixed brushes are exposed to different solvents and the morphology is observed via atomic force and x-ray photoemission microscopy. In a nonselective solvent the different species segregate into parallel cylinders ("ripple structure"). Upon exposure to a selective solvent, we encounter a transition to a "dimple" structure, in which the unfavored component forms clusters. Simultaneously, we observe an enhanced perpendicular segregation. The experimental observations are compared to self-consistent field calculations, where qualitative agreement is found.

Journal Article↗
PubMed2002

Nucleolar protein allocation and ultrastructure in bovine embryos produced by nuclear transfer from granulosa cells.

In the present study immunofluorescence confocal laser scanning microscopy, autoradiography following (3)H-uridine incubation and transmission electron microscopy were used to evaluate the nucleolar protein localization, transcriptional activity, and nucleolar ultrastructure during genomic re-programming in bovine embryos reconstructed by nuclear transfer from granulosa cells into non-activated cytoplasts followed by activation. During the 1st cell cycle (1-cell embryos), no autoradiographic labelling was detected. Ultrastructurally, nucleoli devoid of a granular component were observed. During the 2nd cell cycle (2-cell embryos) autoradiographic labelling was also lacking and the embryos displayed varying degrees of nucleolar inactivation. During both the 3rd (4-cell embryos) and 4th (tentative 8-cell embryos), cell cycles autoradiographic labelling was lacking in some embryos, while others displayed labelling and associated formation of fibrillo-granular nucleoli. During the 5th cell cycle (tentative 16-cell embryos), all embryos displayed autoradiographic labelling and fibrillo-granular nucleoli. In some blastomeres, however, deviant nucleolar ultrastructure was observed. During the first cell cycle labelling of RNA polymerase I, fibrillarin, upstream binding factor (UBF) and nucleolin (C23) was localized to nuclear entities. During the 2nd cell cycle, only labelling of RNA polymerase I and fibrillarin persisted. During the 3rd and 4th cell cycle labelling of fibrillarin persisted, labelling of nucleophosmin (B23) appeared and that of nucleolin re-appeared. During the 5th cell cycle almost all embryos showed complete labelling of all proteins except for UBF, which lacked in more than half of the embryos. In conclusion, bovine granulosa cell nuclear transfer embryos showed re-modelling of the nucleoli to an inactive form followed by re-formation of fibrillo-granular nucleoli. The re-formation of fibrillo-granular nucleoli was initiated already during the 3rd cell cycle, which is one cell cycle earlier than in in vivo- and in vitro-derived bovine embryos. Moreover, in more than half of the embryos, UBF could not be immunocytochemically localized to the nucleolar compartment during the 5th cell cycle indicating lack of developmental potentials.

Animals↗
PubMed2002

Expression and characterization of functional recombinant bovine follicle-stimulating hormone (boFSHalpha/beta) produced in the milk of transgenic rabbits.

Bovine follicle-stimulating hormone (boFSH) is a heterodimeric glycoprotein that belongs to the pituitary gonadotropins. Bioactive FSH is composed of alpha and beta subunits which require extensive N-glycosylation and sialylation. The mammary gland of transgenic livestock is an attractive source for the synthesis of post-translationally modified proteins. Two mammary gland-specific gene constructs with the cDNA for the boFSH alpha (boFSHalpha) and beta (boFSHbeta) subunits controlled by bovine alpha-s1 casein regulatory sequences were co-microinjected into fertilized rabbit oocytes. Two FSHalpha/FSHbeta double transgenic rabbit lines were established. The transgene expression was strictly lactation and mammary gland specific. Protein analysis revealed the presence of the boFSH heterodimer in the milk of transgenic rabbits showing a molecular weight similar to that of purified pituitary gland derived boFSH (boFSH-P). Subunit specific antibodies detected both polypeptides with the expected molecular sizes. Biochemical characterization demonstrated the expected isoelectric points of the recombinant boFSH. The presence of the post-translationally added terminal sialic acid residues was indicated by wheat germ agglutinin (WGA) lectin Western blotting. The biological activity of the recombinant mammary gland produced boFSH was determined using a FSH-dependent reporter cell line. The bioactivity of the recombinant boFSH was comparable to that of purified boFSH-P.

Animals↗
PubMed2002

[Partial CO(2) rebreathing technique versus thermodilution: measurement of cardiac output before and after operations with extracorporeal circulation].

BACKGROUND: The NICO(2) monitor determines "pulmonary capillary blood flow" (Qpc) and cardiac output (Qt) using the "partial CO(2) rebreathing technique". The agreement between NICO(2) and thermodilution (TD) cardiac output was compared before and after cardiac surgery with cardiopulmonary bypass (CBP). In addition, the possibility of calculating the intrapulmonary shunt fraction (Qs/Qt) by combining data from the NICO(2) monitor and the TD was investigated. METHODS: In 32 patients measurements were made following induction of anesthesia ("pre-CBP"), 30 min after weaning from CBP ("post-CBP"), and 6-8 h after surgery ("post-OP"). Qt was determined by the NICO(2) monitor and TD, Qpc by the NICO(2) monitor, and Qs/Qt(O(2)) from the standard formula. An intrapulmonary shunt was calculated using Qpc(NICO(2)) and Qt(TD) according to the equation Qs/Qt=1-Qpc/Qt. Bland-Altman and regression analysis techniques were used for statistical evaluation. RESULTS: "Pre-CBP" there was a good agreement between Qt(NICO(2)) and Qt(TD) with both a bias and precision of -0.13+/-0.46 l/min and a correlation of r=0.88+/-0.47 ( p<0.001). In contrast, "post-CBP" and "post-OP" there was a lack of agreement for Qt (bias and precision: 0.97+/-1.05 l/min and -0.33+/-0.8 l/min, respectively). Regarding the shunt calculations no significant correlations between methods could be found. CONCLUSION: Cardiac output measurement by the NICO(2) monitor agree well with TD under steady-state conditions but after CBP the agreement was too small. Combining Qpc(NICO(2)) and Qt(TD) does not offer a reliable possibility for calculating intrapulmonary shunt.

Algorithms↗
PubMed2002

[Iatrogenic "metalloma" (titanoma) caused by implant failure in "metal-backed" patellar joint surface replacement].

Patellofemoral problems frequently provide the cause for revisions after total knee replacements (TKR). Problems with metal-backed patellae, in particular, have been reported on in the past, with a failure rate of 33%. As a result of implant failure, there is an increase of polyethylene and metallic wear, which eventually leads to a synovialitis and metallosis. We report a case of a iatrogenic induced metallosis of the knee joint resulting from failure of a metal-backed patella component with the formation of a substantial pseudotumor within the popliteal fossa. Intraoperatively, a browny-grey, knotted and hard structure was to be seen, which histologically imposed as a hyalinated scar tissue with black particular deposits. Energy dispersive X-ray microanalysis showed a high level of titanium within the intra- and extracellular deposits. In differential diagnosis these findings were postulated as "metalloma" (titanoma). In cases of periprosthetic pseudotumors, particular those with implant failure, a iatrogenic-induced metalloma should be considered.

Adult↗
PubMed2002

Optimizing local anesthesia during 10-core biopsy of the prostate.

OBJECTIVES: To examine, in a prospective, randomized study, the effect of different anesthetic techniques versus no anesthesia in a 10-core prostate biopsy. Reports thus far have shown a high variability in assessing the pain intensity of prostate biopsies and the effectiveness of anesthesia. METHODS: Ultrasound-guided 10-core prostate biopsy was performed. Patients were prospectively randomized into four groups: no local anesthesia (group 1); anesthetic block of the prostatic plexus (group 2); local anesthesia onto the capsula of the apex (group 3); and a combination of the anesthesia used for groups 2 and 3 (group 4). The degree of pain was recorded using the visual analog scale/numeric analog scale (VAS/NAS) score. RESULTS: The study included 187 patients. Results were assessed in 170 patients: 44 in group 1, 44 in group 2, 40 in group 3, and 42 in group 4. In group 1 (no anesthesia), 2 (4.5%) of 44 patients had no pain during biopsy (VAS/NAS = 0); the pain was mild (VAS/NAS of 1 to 4) in 38 (86.4%), moderate (VAS/NAS of 4 to 7) in 3 (6.8%), and severe (VAS/NAS of greater than 7) in 1 (2.3%) of 44 patients. The mean pain scores were 2.33 in group 1, 1.68 in group 2 (P = 0.05), 1.07 in group 3 (P <0.001), and 1.23 in group 4 (P <0.001). Pain caused by the local anesthesia itself was 0 in group 1, 1.52 in group 2 (P = 0.001), 1.05 in group 3 (P = 0.001), and 1.79 in group 4 (P = 0.001). CONCLUSIONS: Local anesthesia significantly reduces pain. An injection onto the capsule at the apex was the most effective technique. It is technically easier to perform than an anesthetic block of the prostatic plexus and can be recommended.

Aged↗
PubMed2002

ATP-independent anoxic activation of ATP-sensitive K+ channels in dorsal vagal neurons of juvenile mice in situ.

The role of ATP in anoxic activation of ATP-sensitive K+ (KATP) channels was studied in dorsal vagal neurons of mouse brainstem slices. In the whole-cell configuration, cyanide-induced chemical anoxia evoked within 10 s a 300-pA outward current that gave rise to a hyperpolarization of 24 mV. These responses were mimicked by nitrogen-aerated saline, rotenone or diazoxide and abolished by tolbutamide. The cyanide-induced hyperpolarization was due to activation of 70 pS K(ATP) channels that were half-maximally blocked by 5 microM internal ATP. Dialyzing the cells with either 1, 20 or 0 mM ATP did not, however, affect the time to onset, the kinetics or the magnitude of the cyanide-induced hyperpolarization. Impairment of ATP consumption by ouabain, vanadate or reduced temperature had no effect either. Thus, anoxia-induced activation of these KATP channels cannot be explained by a fall of cellular ATP or a concomitant rise of ADP. Anoxia-related changes of the actin cytoskeleton or the composition of the plasma membrane are also not likely to be involved, as cytochalasin D did not affect the cyanide-evoked hyperpolarization and phosphatidylinositol 4,5-bisphosphate failed to decrease the ATP sensitivity of single KATP channels. Finally, because of a lack of effects of reduced/oxidized glutathione and the oxidase blocker diphenyliodonium on the cyanide-induced hyperpolarization, cellular redox state does not appear to be involved. Our results indicate that despite a high sensitivity to ATP in excised patches, anoxic activation of KATP channels is independent of cellular ATP. Rather the ATP block seems to be removed as a consequence of impaired mitochondrial function.

Actin Cytoskeleton↗
PubMed2002

Pulse contour analysis versus thermodilution in cardiac surgery patients.

BACKGROUND: Previous studies have demonstrated that there is a lack of agreement between intermittent cold bolus thermodilution (ICO) and a semicontinuous method with dilution of heat (CCO) in cardiac surgical patients following hypothermic extracorporeal circulation (HCPB). Therefore, the aim of the present study was to compare both ICO and CCO with continuous pulse contour analysis (PCCO): a method based on a fundamentally different principle of determining cardiac output (CO). METHODS: A prospective criterion standard study of 25 cardiac surgery patients undergoing HCPB. Cardiac output was determined using the three methods (ICO, CCO, and PCCO) before and after HCPB up to 12 h after arrival on the ICU. Bias and precision were evaluated. RESULTS: A total of 380 triple determinations of CO could be analyzed. During the entire study period bias PCCO-ICO was -0.14 l*/min (precision 1.16 l*/min) and bias CCO-ICO was -0.40 l*/min (precision 1.25 l*/min). Up to 45 min after bypass PCCO agreed with ICO (bias -0.21 l*/min, precision 1.37 l*/min), while bias CCO-ICO was -1.30 l*/min (precision 1.45 l*/min). CONCLUSION: The agreement between PCCO and ICO in contrast to CCO in the first 45 min after HCPB indicates that CCO underestimates CO during this period.

Adult↗
PubMed2002

Socio-economic and schooling status of dental undergraduates from six French universities.

OBJECTIVES: The aim of this study was to evaluate the socio-economic status of French undergraduate dental students. METHODS: A 46-item questionnaire was completed by the dental students of six universities between 1992 and 1995. Subjects related to family background, housing, schooling, income, expenditure and participation in student life were investigated. RESULTS: A total of 1192 out of 1207 questionnaires were returned. Both genders had equal access to dental training. The average overall cost of the four last years of the dental course was 30,302 French francs and varied greatly between faculties, as did the number of hours spent at the faculty for lectures, tutorials and practicals, and clinical work. Overall, the majority of students came from a well off social background, and had a relatively high quality of life while a small minority received no support from their families. Thirty-four per cent of students had never worked. One third of students smoked and one third regularly consumed medication of some sort. A third did not participate in any sport. Only 25% students bought dental text books and 42% of the students reported using the library regularly. CONCLUSIONS: This study offers an accurate description of the socio-economic status of French dental students that could be used as a reference for comparable studies in other European countries.

Adult↗
PubMed2002

Complexities in ETS-domain transcription factor function and regulation: lessons from the TCF (ternary complex factor) subfamily. The Colworth Medal Lecture.

The ETS-domain transcription factor family can be divided into a series of subfamilies. Elk-1 represents the founding member of the ternary complex factor (TCF) subfamily. By focusing on the TCF subfamily, we can demonstrate the complexities that exist in the function and regulation of ETS-domain transcription factors. This article focuses on Elk-1 in detail and summarizes the functions of other TCFs. The key themes covered include the domain structure of the TCFs, the mechanisms of complex formation with serum response factor, regulation of TCFs by mitogen-activated protein kinase cascades, and transcriptional regulatory properties of the TCFs. Finally, the emerging role of the TCFs in vivo is discussed. A picture is developing indicating that, while these proteins exhibit significant sequence and functional conservation, key differences in their structure and regulation are being identified which may relate to unique functions of these proteins in vivo.

Amino Acid Sequence↗
PubMed2002

Effects of desflurane and isoflurane on intestinal tissue oxygen pressure during colorectal surgery.

Volatile anaesthetics differ in the effects they have on splanchnic haemodynamics and oxygenation. The aim of this study was to evaluate the effects of desflurane and isoflurane as part of a balanced anaesthetic technique on intestinal tissue oxygenation during colorectal surgery. Data were analysed from 44 patients randomly assigned to receive either desflurane (desflurane group, n = 20), or isoflurane (isoflurane group, n = 24) for inhalational anaesthesia. Tissue oxygen pressure (P(tiss)O2) was measured on the serosal side of the large intestine prior to colonic resection (T1) and following the completion of the bowel anastomosis (T2). In addition, haemodynamic and oxygenation parameters were assessed. No difference in mean P(tiss)O2 was observed between the groups at T1 [desflurane group: 8.1 (2.9) kPa vs. isoflurane group: 7.7 (2.7) kPa]. Following completion of the anastomosis (T2) mean P(tiss)O2 was higher in the isoflurane group [9.6 (2.9) kPa] than the desflurane group [7.7 (2.4) kPa, p = 0.025]. During surgery no difference between the groups could be observed with regard to haemodynamics and global oxygenation parameters. The lack of a difference between the groups in P(tiss)O2 before resection of the colon suggests that, under normal conditions, desflurane and isoflurane have comparable effects on intestinal blood flow and oxygenation. However, following local ischaemia, the reactive hyperaemia seems to be better preserved during isoflurane anaesthesia indicated by a local increase in P(tiss)O2blank(p = 0.013) following completion of the bowel anastomosis.

Adult↗
PubMed2002

The effect of a pre-operative infusion of Ringer's solution on splanchnic perfusion in patients undergoing coronary artery bypass grafting.

Surgical patients develop a fluid deficit during pre-operative starvation. This study examines the effects of pre-operative fluid administration on haemodynamic variables, oxygenation and splanchnic perfusion in patients undergoing elective coronary artery bypass grafting. Forty-eight patients were randomised to receive either a pre-operative crystalloid infusion (crystalloid group, n = 24) or no infusion (control group, n = 24). Patients in the crystalloid group received a continuous infusion of Ringer's solution at 1.5 ml.kg(-1).h(-1) from 22:00 h until induction of anaesthesia the next morning. Immediately before induction of anaesthesia, all patients were given a colloid infusion to increase pulmonary capillary wedge pressure and central venous pressure to similar levels in both groups. Haemodynamic and oxygenation parameters were measured using invasive cardiovascular monitoring, and splanchnic perfusion was assessed by indocyanine green clearance. Patients in the crystalloid group received a mean (SD) of 1008 (140) ml of Ringer's solution overnight. Patients in the crystalloid group had a higher splanchnic blood flow than the control group before induction of anaesthesia [mean (SD) = 1782 (573) ml.min(-1) vs. 1391 (333) ml.min(-1), p < 0.05]. There were no significant differences in systemic haemodynamic data and global oxygenation parameters between the two groups. Pre-operative infusion of crystalloid appears to result in an improvement in pre-operative splanchnic perfusion.

Aged↗
PubMed2002

Quantification of telomerase activity, porphobilinogen deaminase and human telomerase reverse transcriptase mRNA in testicular tissue - new parameters for a molecular diagnostic classification of spermatogenesis disorders.

The aim of the study was to evaluate the quantitative detection of human telomerase reverse transcriptase (hTERT) mRNA and telomerase activity as new molecular diagnostic parameters for a subclassification of spermatogenesis disorders. Telomerase activity was detected by a quantitative telomerase PCR ELISA, and hTERT mRNA expression was quantified by fluorescence real-time RT-PCR in a LightCycler in cryopreserved testicular tissue specimens. This was paralleled by a histological workup. The discriminant analysis showed that detection of normalized hTERT expression was able to correctly classify 89.0% of the investigated tissue specimens into the subgroups of full spermatogenesis, maturation arrest or Sertoli-cell-only syndrome. In contrast, discriminant analysis revealed an only 58% accuracy of telomerase activity for the investigated tissue specimens. This study shows that the quantification of hTERT expression in testicular tissue by real-time fluorescence RT-PCR is well suited for correctly classifying spermatogenesis disorders and proved to be markedly superior to the determination of telomerase activity.

Biopsy↗
PubMed2002

Intestinal and renal handling of oxalate in magnesium-deficient rats. Evaluation of intestinal in vivo 14C-oxalate perfusion.

OBJECTIVE: To clarify in vivo, using isolated small intestinal loops perfused with radioactive 14C-oxalate, whether intestinal hyperabsorption or reduced secretion is important in magnesium deficiency (MgD), as this is a potential cause of calcium oxalate urolithiasis. MATERIALS AND METHODS: Twenty-four Sprague-Dawley rats were either fed a standard diet (control, 12 rats) or a magnesium-deficient diet (MgD, 12 rats) for 19 weeks. One hour before the animals were killed, a defined length of a small intestinal loop was isolated and filled with 5 mL of 0.9% NaCl and a defined amount of intravenous 14C-oxalate applied. Using this method it was possible to determine the secretion of unlabelled oxalate into the intestinal lumen, from the specific activity in plasma. RESULTS: Plasma oxalate levels doubled under MgD; urinary calcium and phosphorus also increased significantly, while urine oxalate tended to decrease. The secretion of oxalate into the intestinal lumen of MgD animals increased significantly, by five times that of the control. The relative supersaturation for calcium oxalate remained constant. Elementary analysis of renal tissue showed an increase in calcium and phosphorus under MgD, in the sense of nephrocalcinosis, but no concretions were detected (no nephrolithiasis). CONCLUSION: In contrast to earlier studies, there is no evidence that hyperoxaluria is responsible for the possible development of urolithiasis in MgD. This was confirmed by calcium phosphate deposits in renal tissue, even though there was no evidence of oxalate urolithiasis. The increase in plasma oxalate seems to be completely compensated by strongly increased oxalate secretion into the intestinal lumen.

Animals↗
PubMed2002

The new German allocation system for donated thoracic organs causes longer ischemia and increased costs.

OBJECTIVE: Allocation criteria changed in 2000 as a result of Germany's new transplantation law. Before, thoracic organs were primarily allocated electively within the donor region (according to urgency and waiting time). Afterwards, all patients in Germany eligible for heart transplants were registered in a national waiting list. With the exception of high-urgency patients that are approved by an audit committee, waiting time has become the major criteria for allocation. In this study, we investigated the impact of the new allocation system on economic aspects as on clinical results. METHODS: One year in the new allocation system (NA) was compared to the previous year in the old allocation system (OA) regarding explantation/transportation distance, costs, ischemia time and clinical outcome. All explantations performed by our institution within Germany were evaluated. RESULTS: The number of transplantations and the spectrum was similar between the two time periods (NA vs. OA: 61 vs. 57 overall). Eighty-two percent of these explanted organs were transplanted within the donor region in the OA time period, but only 37 % in the NA period. This resulted in higher transportation distances (NA: 441 +/- 177 km vs. OA: 179 +/- 118 km), higher transportation cost (NA: EUR 4,472 +/- 2,858 per explantation vs. OA: EUR 1,858 +/- 2,293 explantation, p = 0.001), and therefore longer ischemia times in the NA period (NA: 264 +/- 56 min: OA: 208 + 61 min, p = 0.001). Perioperative results and survival after a mean clinical follow-up of 21 +/- 8 (OA) and 11 +/- 5 (NA) months were comparable (86 % vs. 87 % (p = 0.93). CONCLUSION: Transportation distance, costs for explantation and ischemia time increased significantly with the NA period. While the clinical short-term outcome proved to be comparable, we cannot yet judge the long-term impact of the prolonged ischemia time on the development of chronic rejection.

Germany↗
PubMed2002

[The free gracilis perforator flap for autologous breast reconstruction].

The free gracilis perforator flap is an alternative possibility for autologous breast reconstruction, if previous abdominal operations preclude this donor site, or if there is atypical distribution of fat tissue. The perforator flap is based on the main pedicle of the gracilis muscle. The muscle itself and its innervation can be completely preserved, if the angiosome of this vascular pedicle offers sufficient tissue. In skinny patients however it may be necessary to include the neighbouring angiosome of the second gracilis pedicle by means of the intramuscular anastomosis between both pedicles. In such a case a thin muscle strip with the joining vessel must be included in the flap. The bulk of the gracilis muscle and its motor nerve can, however, still be preserved. Breast reconstruction with this technique was successfully performed on six patients (two bilateral). It is a good alternative to a reconstruction with gluteal, or anteromedial, or lateral thigh perforator flaps.

Adult↗
PubMed2002

Pharmacokinetic and mass balance study of unlabelled and (14)C-labelled emedastine difumarate in healthy volunteers.

1. In a mass balance study, six healthy male volunteers received a single oral dose of 4 mg (14)C-labelled emedastine difumarate. The pharmacokinetics of the total radioactivity and unchanged drug were assessed over 48 h. Urinary and faecal excretion were measured over 120 h. Additionally, urinary metabolites were investigated. 2. In a single- and multiple-dose pharmacokinetic study, nine male and nine female healthy volunteers received 2 mg oral emedastine difumarate b.i.d. or 4 mg o.d. for 7 consecutive days. The plasma pharmacokinetics were assessed on day 1 and at steady-state. 3. The mass balance study demonstrated almost complete gastrointestinal absorption of the administered dose. A total of 94.2% of the radioactivity was eliminated via the kidneys. Unchanged emedastine in the urine accounted for <5% of dose. 5-Hydroxy, 6-hydroxy and N-oxide metabolites previously identified in the Japanese were present in Caucasian subjects. 4. AUC after single and multiple dosing were dose-proportional. On day 7, no statistical difference in AUC(0-24) could be detected between the two regimens, with AUC = 70.6 +/- 36.1 and 71.7 +/- 52.3 ng h ml(-1), respectively. There were no gender differences in the pharmacokinetics of emedastine. 5. The results corroborate the use of emedastine in a Caucasian population and support the extrapolation of safety and efficacy data from Asians to Caucasians.

Adult↗