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Biomedical subjects

P Steffen

Publications and source records attributed to P Steffen.

At least 19 recordsLinked to original sources
PubMed2006

[Delta(9)-tetrahydrocannabinol and the opioid receptor agonist piritramide do not act synergistically in postoperative pain].

BACKGROUND: It is concluded from animal experiments that cannabinoid receptor and mu-opioid receptor agonists act synergistically with respect to antinociception. In order to demonstrate this effect under clinical conditions, we conducted a randomized double blind trial with patients after radical prostatectomy. PATIENTS AND METHODS: From the evening before the operation until the morning of the second postoperative day, all patients received eight oral doses of either placebo or 5 mg Delta(9)-tetrahydrocannabinol (dronabinol). Postoperatively patients had access to patient-controlled analgesia with the micro-opioid agonist piritramide for 48 h. We expected patients receiving dronabinol to require significantly less piritramide compared to patients on placebo. RESULTS: The consumption of piritramide was recorded in 100 patients after radical retropubic prostatectomy with regional lymphadenectomy. Patients in the placebo group consumed 74 mg (median), interquartile range (IQR) 44-90 mg, patients in the verum group consumed 54 mg (median) IQR 46-88 mg. The difference between groups was not statistically significant. Plasma concentrations of Delta(9)-THC were measurable in all patients in the verum group. The levels (median) were 1.5 ng/ml (IQR 0.6-2.3), 1.3 ng/ml (IQR 0.5-2.2) and 1.9 ng/ml (IQR 0.8-2.7) on the day of operation, the first and second postoperative day, respectively. CONCLUSION: We found neither a synergistic nor even an additive antinociceptive interaction between Delta(9)-tetrahydrocannabinol and the micro-opioid agonist piritramide in a setting of acute postoperative pain.

Aged↗
PubMed2004

[Postoperative analgesia with rofecoxib. How effective is the preoperative application of a 25 mg dose?].

OBJECTIVE: The purpose of this study was to evaluate the analgesic efficacy of 25 mg rofecoxib. METHODS: In a randomized, prospective double-blind study we investigated the analgesic efficacy of 25 mg rofecoxib in 62 patients scheduled for minor trauma surgery. Patients received 2 h before induction of anesthesia either 25 mg rofecoxib (verum) orally or placebo. These applications were repeated postoperatively after 24 h. Postoperative pain intensity was measured by the numeric rating scale (NRS). All patients were allowed to order piritramid from a PCA-device (bolus 2 mg, lockout 5 min in the recovery room, 15 min on the ward) for 24 h after surgery. 10/20/30 min, as well as 1/2/4/6 h and 24 h after surgery cumulated doses of piritramid, pain scores (0-10) and side effects were recorded. RESULTS: Pain relief and cumulated doses of piritramid in both groups were comparable at all points in time. There were no significant differences in the incidence of side effects between the two groups. CONCLUSION: Preoperative application of 25 mg rofecoxib is not effective for postoperative analgesia in patients after minor trauma surgery.

Adult↗
PubMed2003

Limits on diffuse fluxes of high energy extraterrestrial neutrinos with the AMANDA-B10 detector.

Data from the AMANDA-B10 detector taken during the austral winter of 1997 have been searched for a diffuse flux of high energy extraterrestrial muon neutrinos. This search yielded no excess events above those expected from background atmospheric neutrinos, leading to upper limits on the extraterrestrial neutrino flux measured at the earth. For an assumed E-2 spectrum, a 90% classical confidence level upper limit has been placed at a level E2Phi(E)=8.4 x 10(-7) cm(-2) s(-1) sr(-1) GeV (for a predominant neutrino energy range 6-1000 TeV), which is the most restrictive bound placed by any neutrino detector. Some specific predicted model spectra are excluded. Interpreting these limits in terms of the flux from a cosmological distributions of sources requires the incorporation of neutrino oscillations, typically weakening the limits by a factor of 2.

Journal Article↗
PubMed2002

Cavitation of Langmuir monolayers.

Cavitation in liquid expanded and liquid condensed Langmuir monolayers induced by laser heating or microbubble coalescence is studied experimentally using fluorescence and Brewster angle microscopy. The kinetics of hole closure of two-dimensional (2D) gaseous cavitation bubbles exhibits a decelerated dynamics for cavities surrounded by a liquid expanded phase and an accelerated dynamics for cavities in a liquid condensed phase. Most of the cavities in liquid condensed phases possess a nonconvex shape and do not close. The results are compared with theoretical predictions derived for 2D cavitation of liquid monolayers of different surface shear viscosities, and for solid monolayers with diffusive flux of vacancies and interstitials. While part of the theory is in qualitative agreement with the experiment, the experimentally observed hole persistence within the liquid condensed phases and the hole closure within liquid expanded phases remains to be explained. The technique of microbubble coalescence might be particularly useful for the study of the rheological properties of hexatic phases.

Journal Article↗
PubMed2001

Blunted nighttime blood pressure dipping in postmenopausal women.

Blunting of the normal drop in blood pressure (BP) from day to night is emerging as a strong prognostic indicator of cardiovascular morbidity and mortality. This study evaluated the effects of natural menopause on BP dipping in African American and white women. A total of 112 women (62 premenopausal and 50 postmenopausal) took part in the study. Pre- and postmenopausal groups were comparable in terms of clinic BP, body mass index, and ethnic composition. Ambulatory BP was recorded over 24 h during a typical workday, with measurements programmed to be taken every 15 min during waking hours and every 30-minutes during sleeping hours. Nocturnal BP dipping was defined as the difference between waking and sleep BP. Waking BP did not differ by menopausal status. However, nocturnal systolic BP (SBP) and diastolic BP (DBP) dipping were attenuated in postmenopausal women, with both SBP (P < .05) and DBP (P < .05) higher during nighttime sleep in postmenopausal than in premenopausal women. Ethnicity was also related to BP dipping, with African American women tending to show blunted SBP dipping (P = .055) compared with white women; BP dipping was most blunted in postmenopausal African American women. These observations suggest that blunted nighttime BP dipping may contribute to increased cardiovascular disease risk in postmenopausal women.

Black People↗
PubMed2000

Listeria monocytogenes ActA protein interacts with phosphatidylinositol 4,5-bisphosphate in vitro.

The N-terminal region of the Listeria monocytogenes ActA protein, in conjunction with host cell factors, is sufficient for actin polymerization at the bacterial surface. Previous data suggested that ActA could protect barbed ends from capping proteins. We tested this hypothesis by actin polymerization experiments in the presence of the ActA N-terminal fragment and capping protein. ActA does not protect barbed ends from capping protein. In contrast, this polypeptide prevents PIP(2) from inhibiting the capping activity of capping protein. Gel filtration and tryptophan fluorescence experiments showed that the purified ActA N-terminal fragment binds to PIP(2) and PIP, defining phosphoinositides as novels ligands for this functional domain of ActA. Phosphoinositide binding to the N-terminal region of ActA may induce conformational changes in ActA and/or facilitate binding of other cell components, important for ActA-induced actin polymerization.

Actin Depolymerizing Factors↗
PubMed2000

Initial extractions and tooth loss during supportive care in a periodontal population seeking comprehensive care.

BACKGROUND/AIMS: This retrospective survey was aimed at determining the prevalence of tooth extractions and the dental pathologies associated with them during both the active and maintenance phase of periodontal therapy in a periodontal population seeking comprehensive dental care. METHODS: A total of 273 randomly selected subjects from the oral prophylaxis clinic of the University of Berne were included. All subjects had received comprehensive care consisting of periodontal and restorative treatment and participated in a supervised maintenance program for an average of 67+/-46 months (range 5 to 278 months). The population consisted of 39.6% current smokers and 27.8% previous smokers. 6.2% of the patients had gingivitis, 20.5% mild periodontitis, 48.4% moderate and 24.9% severe periodontitis. The average frequency of the recall visits was 4.4+/-1.5 appointments/year (range 1.7-12 appointments/year). RESULTS: Results indicated that 574 out of a total of 6503 teeth were extracted; 311 teeth were extracted during active therapy and 263 during the supportive periodontal care (SPC) phase of therapy. 46% of patients received tooth extractions as part of their active treatment and 41% during their participation in the secondary prevention program. In the subgroup whose treatment plan included extractions the average number was 2.5+/-1.6 teeth per patient. Likewise, the patients who received extractions during recall lost an average of 2.35+/-1.9 teeth per subject with an incidence of 0.4+/-0.37 teeth per patient per year. These data reinforce the concept that a minority of the population is responsible for the majority of tooth extractions, both during active therapy and SPC. Periodontal disease was the only pathology observed at 57% of the extracted teeth; while caries, endodontic pathology and technical problems in the absence of periodontitis were observed in 29% of cases. CONCLUSIONS: These observations indicate that the rendered treatment was effective in the long-term maintenance of the dentition of these subjects and suggest that advanced periodontal disease represented the major cause of tooth loss in this population.

Adolescent↗
PubMed1998

An efficient Fourier method for 3-D radon inversion in exact cone-beam CT reconstruction.

The radial derivative of the three-dimensional (3-D) radon transform of an object is an important intermediate result in many analytically exact cone-beam reconstruction algorithms. We briefly review Grangeat's approach for calculating radon derivative data from cone-beam projections and then present a new, efficient method for 3-D radon inversion, i.e., reconstruction of the image from the radial derivative of the 3-D radon transform, called direct Fourier inversion (DFI). The method is based directly on the 3-D Fourier slice theorem. From the 3-D radon derivative data, which is assumed to be sampled on a spherical grid, the 3-D Fourier transform of the object is calculated by performing fast Fourier transforms (FFT's) along radial lines in the radon space. Then, an interpolation is performed from the spherical to a Cartesian grid using a 3-D gridding step in the frequency domain. Finally, this 3-D Fourier transform is transformed back to the spatial domain via 3-D inverse FFT. The algorithm is computationally efficient with complexity in the order of N3 logN. We have done reconstructions of simulated 3-D radon derivative data assuming sampling conditions and image quality requirements similar to those in medical computed tomography (CT).

Algorithms↗
PubMed1998

Hybrid Bordetella pertussis-Escherichia coli RNA polymerases: selectivity of promoter activation.

We constructed hybrid Bordetella pertussis-Escherichia coli RNA polymerases and compared productive interactions between transcription activators and cognate RNA polymerase subunits in an in vitro transcription system. Virulence-associated genes of B. pertussis, in the presence of their activator BvgA, are transcribed by all variants of hybrid RNA polymerases, whereas transcription at the E. coli lac promoter regulated by the cyclic AMP-catabolite gene activator protein has an absolute requirement for the E. coli alpha subunit. This suggests that activator contact sites involve a high degree of selectivity.

Amino Acid Sequence↗
PubMed1997

[Postoperative analgesia after endoscopic abdominal operations. A randomized double-blind study of perioperative effectiveness of metamizole].

In comparison to conventional operating technique endoscopic surgery reveals numerous advantages, particular rapid mobilisation and earlier discharge from observation. For a effective utilization of these advantages, it is desirable to have a efficient postoperative analgesic scheme, which can be continued into the period after discharge from hospital. In a randomised, prospective double-blind study we investigated the analgesic efficacy of dipyrone in 40 patients, scheduled for endoscopic abdominal surgery (mainly endoscopic cholecystectomy). Patients received before induction of anesthesia either dipyrone (1 g/100 ml NaCl i.v.) or placebo (100 ml NaCl i.v.). These infusions were repeated 6 h and 12 h after first application. After surgery all patients were allowed to self-administer buprenorphine intravenously from a PCA-pump (Bolus 30 micrograms, lockout 5 min in the recovery room, 30 min on the ward). Every hour for the first 6 h and after 24 h, cumulated doses of buprenorphine, pain scores (0-10), pulse, blood pressure and side effects were recorded. Dipyrone-treated patients had significantly less pain immediately after surgery and used a significantly lower cumulated dose of buprenorphine (-67%; 90 micrograms vs. 270 micrograms buprenorphine) in the first 24 h after surgery.

Adolescent↗
PubMed1997

The Bordetella pertussis sigma subunit of RNA polymerase confers enhanced expression of fha in Escherichia coli.

We have cloned the rpoD gene coding for the major sigma factor of Bordetella pertussis. The deduced amino acid sequence reveals a protein of 733 residues which has extensive amino acid homology with the principal sigma factors of a number of divergent prokaryotes. It is larger than most sigma factors identified to date, having a molecular mass of 81.3 kDa. We have designated this factor sigma 80. In a heterologous complementation assay, B. pertussis rpoD was able to complement the Escherichia coli rpoD temperature-sensitive mutant UQ285. Furthermore, B. pertussis rpoD conferred better specificity to the E. coli RNA polymerase, allowing increased expression of the B. pertussis virulence-associated tha promoter, but could not activate the ptx and cya promoters in the E. coli UQ285 strains carrying the B. pertussis bvg locus. We discuss the implications of these results on the mechanisms involved in the activation of virulence-associated promoters.

Amino Acid Sequence↗
PubMed1997

[Effectiveness, side effects and costs of postoperative pain therapy: intravenous and epidural patient-controlled analgesia (PCA)].

PURPOSE: Improvement of the quality of analgesia, reduction of side effects and costs by application of epidural (PCEA) in comparison to intravenous patient-controlled analgesia (PCA) in postoperative pain treatment. METHODS: 62 patients with upper abdominal surgery took part in this randomised prospective study which was approved by the local ethics committee. Epidural catheters were inserted at T 8/9 (group PCEA). General anaesthesia was performed with propofol, sufentanil 2 micrograms/kg, pancuronium, enflurane and O2:N2O = 1:2. Postoperative analgesia consisted of epidural bupivacaine 0.25% + sufentanil 2 micrograms/ml (BS). (bolus 0.05 ml/kg, lockout 10 min) in group PCEA, or of intravenous morphine (bolus 2 mg. lockout 10 min) in group PCA. The following parameters were recorded until the evening of postoperative day 4: pain intensity at rest (VASR, 1-10) and on coughing (VASH, 1-10), blood pressure, heart rate, blood gas analysis, ability to ambulate, pruritus, nausea/vomiting (PONV), patient satisfaction (0-4), time and expenses for postoperative pain treatment. RESULTS: Median VASR (1 vs 2) and VASH (3 vs 4.5) were lower, cough intensity (2 vs 1) and patient satisfaction score (4 vs 3) were higher in PCEA compared to PCA. Ability to ambulate, pruritus, PONV, haemodynamics, paO2 and paCO2 were comparable. Postoperative pain treatment with PCEA was more time-consuming (407 vs 299 min) and expensive (71 vs 40 S/day) than PCA. CONCLUSION: PCEA in comparison to PCA after major abdominal surgery provides superior analgesia with comparable side effects at approximately 80% higher costs.

Abdomen↗
PubMed1997

[Differential indications for non-opioids for postoperative analgesia III. Analgesic effect of perioperative administration of metamizole plus diclofenac after spinal anesthesia].

PURPOSE: In a previous study we investigated the analgesic efficacy of a combination of metamizol plus diclofenac after general anaesthesia. After minor orthopaedic surgery postoperative opioid requirements were reduced by 73% during the first 24 h after surgery. In the present study, we have investigated the efficacy of this analgesic combination after minor orthopaedic operations performed in spinal anaesthesia. METHODS: Seventy four patients, scheduled for minor orthopaedic surgery, participated in this double-blind, randomised, placebo-controlled study. The setting was comparable to our previous study. Before induction of spinal anaesthesia, verum-treated patients received a diclofenac suppository (100 mg), and metamizol (1 g/100 ml NaCl 0.9% intravenously over 15 min). These infusions were repeated at 6 h and 12 h. In addition to the third infusion, the patients received a further diclofenac suppository (100 mg). Cumulated doses of buprenorphine (PCA, patient-controlled analgesia), pain scores (0-10), blood pressure, heart rate and side effects were recorded during the first 6 h and again at 24 h. RESULTS: After spinal anaesthesia had subsided, all patients required increasing doses of buprenorphine. Verum-treated patients required significantly lower doses during the first 24 h after surgery (median -29%). CONCLUSIONS: The combination of metamizol and diclofenac causes a clinically relevant reduction in opioid requirements after minor orthopaedic surgery in spinal anaesthesia.

Adult↗
PubMed1997

[Fourier analysis as a mathematical model for evaluating and presenting postoperative corneal topography data after non-mechanical perforating keratoplasty].

BACKGROUND: Videokeratography has given the possibility to obtain information in curvature from a much larger region of the cornea than that covered by keratometry. Fourier analysis as a mathematical model can be used to represent real physical attributes of the cornea and to divide corneal topography in its basic components: the zero-frequency component as the mean ring power, the one-cycle component as a representation of decentration and the two-cycle component as a representation of regular corneal toricity. The purpose of this study was the reconstruction of the corneal refraction after penetrating keratoplasty with a small number of characteristic parameters and the evaluation of the time course of the fourier coefficients as indices for a regular astigmatic cornea in the postkeratoplasty period including suture removal. PATIENTS AND METHODS: Fourty patients (group 1: 20 primary dystrophies, group 2: 20 keratoconus) underwent nonmechanical trephination (excimer laser MEL60, Aesculap-Meditec, Heroldsberg, Germany) in penetrating keratoplasty. All procedures (7.5 mm in dystrophies, 8.0 mm in keratoconus, 8 orientation teeth, double-running 10-0 nylon suture) were performed by one surgeon. At a postoperative gate of 6 weeks, 6 months, before partial suture removal and after complete suture removal, corneal topography (TMS1, Tomey, Tennenlohe, Germany), keratometry, visual acuity and subjective refraction were assessed. Radial approximation with a 5th order polynomial fit of the refractive data on 25 non-centric rings of the TMS, within 256 hemimeridians was performed to get data at equally spaced concentric rings. Fast Fourier transformation of the data sets in the mid periphery (1.4-1.8 mm apical distance) was done to get DC-, one-cycle and two-cycle component. Fourier coefficients were correlated with keratometric readings, subjective refractive values and visual acuity. RESULTS: Spherical equivalent was fairly constant in the postoperative interval before suture removal. After suture removal, a corneal flattening of about 3 diopters occurred. The one-cycle component before suture removal tended to be higher in group 1 compared to group 2 before suture removal. This difference was statistically significant (p = 0.01) after suture removal. Comparing keratometry, calculated meridians by the Tomey software, two-cycle component of the fourier decomposition and subjective refraction, the best correlation (p = 0.02) was observed between two-cycle-component and the refractive cylinder in amplitude and axis after suture removal. Best corrected visual acuity was inversely correlated with the amount of energy of higher harmonics compared to the whole energy before (p = 0.04) and after (p = 0.01) suture removal. CONCLUSIONS: Fourier transformation renders reconstruction of corneal topography data with a marked data reduction and a small error. From fourier coefficients conclusions may be drawn concerning potential best-corrected visual acuity and amplitude/axis of subjective cylinder, even in corneas with severe local irregularities.

Adult↗
PubMed1997

Reduced postoperative analgesic demand after inhaled anesthesia in comparison to combined epidural-inhaled anesthesia in patients undergoing abdominal surgery.

We studied the effect of epidural/general combination anesthesia, in comparison to inhaled anesthesia, on postoperative pain and analgesic consumption in patients undergoing upper abdominal surgery. Anesthesia was induced with propofol and maintained with enflurane in 70% N2O as necessary to maintain arterial blood pressure within 20% of baseline. Group I received bupivacaine 0.25% 0.2 mL/kg and sufentanil 1 microgram/kg 65 +/- 3 min before dermal incision and 0.1 mL/kg bupivacaine 0.25% + sufentanil 2 micrograms/mL (BS) every hour thereafter. Group II received 0.2 mL/kg of BS 316 +/- 15 min after dermal incision in the recovery room. Postoperative patient-controlled epidural analgesia (PCEA) with BS was provided. Pain intensities and consumption of PCEA BS were recorded on postoperative days (PODs) 1 to 5. Inspiratory fraction of enflurane was lower (0.5% +/- 0.01% vs 1.6% +/- 0.04%; P < 0.001) in Group I compared with Group II. Cumulative postoperative consumption of PCEA BS was higher in Group I compared with Group II from the evening of POD 2 until the end of the study (301 +/- 19 mL vs 249 +/- 17 mL; P < 0.001), while pain intensities were comparable at all times. The intraoperative effects of combined BS and enflurane/N2O (inspiratory fraction [Fi] approximately 1 minimum alveolar anesthetic concentration [MAC]) did not preempt postoperative pain in contrast to enflurane/N2O anesthesia (Fi approximately 2.8 MAC).

Abdomen↗
PubMed1997

Epidural bolus clonidine/morphine versus epidural patient-controlled bupivacaine/sufentanil: quality of postoperative analgesia and cost-identification analysis.

UNLABELLED: We compared the costs, quality of analgesia, and side effects of postoperative patient-controlled epidural analgesia (PCEA) with bupivacaine/sufentanil versus an epidural bolus (BOLUS) of clonidine/morphine in 68 patients with pancreatic surgery. Postoperative pain treatment was performed over 4 days: the PCEA pump was filled with bupivacaine 0.25% and sufentanil 2 micrograms/mL and set to 3-mL bolus and 10-min lockout time. BOLUS patients received injections of clonidine 150 micrograms plus morphine 2 mg on demand. Visual analog scale (VAS) score at rest and during coughing, heart rate (HR), systolic arterial pressure (SAP), incidence of postoperative nausea and vomiting, pruritus, duration of intestinal paralysis, hospital treatment, and costs for personnel and material were recorded. VAS scores during coughing (3 +/- 2.5 vs 5 +/- 3, P < 0.001) was higher, and HR (79 +/- 13 vs 89 +/- 15, P < 0.001), and SAP (110 +/- 18 vs 124 +/- 23, P < 0.001) were lower, in the BOLUS compared with the PCEA group. The incidence of hypotension (SAP < 80 mm Hg) was greater (6 vs 0, P < 0.001) in the BOLUS group. The incidence of all other side effects was comparable. The costs of personnel ($204 +/- $40 vs $166 +/- $38, P < 0.001) were higher in the BOLUS group, but the costs of material ($51 +/- $17 vs $87 +/- $18, P < 0.001) were higher in the PCEA group. Total costs ($62 +/- $9 vs $62 +/- $11 per day, P = 0.9) were comparable. We conclude that because of superior analgesia and reduced side effects at analogous costs, PCEA is preferable to the BOLUS technique for the treatment of postoperative pain. IMPLICATIONS: An epidural clonidine/morphine bolus technique resulted in inferior analgesia, more side effects, and comparable costs compared with a bupivacaine/sufentanil patient-controlled regimen in a randomized controlled trial after abdominal surgery.

Adult↗