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Regina Hollweck

Publications and source records attributed to Regina Hollweck.

15 recordsLinked to original sources
PubMed2006

Comparison between breast volume measurement using 3D surface imaging and classical techniques.

Quantification of the complex breast region can be helpful in breast surgery, which is shaped by subjective influences. However, there is no generally recognized method for breast volume calculation. Three-dimensional (3D) body surface imaging represents a new alternative for breast volume computation. The aim of this work was to compare breast volume calculation with 3D scanning and three classic methods, focusing on relative advantages, disadvantages, and reproducibility. Repeated breast volume calculations of both breasts in six patients (n=12) were performed using a 3D laser scanner, nuclear magnetic resonance imaging (MRI), thermoplastic castings, and anthropomorphic measurements. Mean volumes (cc) and mean measurement deviations were calculated, and regression analyses were performed. MRI showed the highest measurement precision, with a mean deviation (expressed as a percentage of mean breast volume) of 1.56+/-0.52% compared with 2.27+/-0.99% for the 3D scanner, 7.97+/-3.53% for thermoplastic castings, and 6.26+/-1.56% for the anthropomorphic measurements. Breast volume calculations using MRI showed the best agreement with 3D scanning measurement (r=0.990), followed by anthropomorphic measurement (r=0.947), and thermoplastic castings (r=0.727). Compared with three classical methods of breast volume calculation, 3D scanning provides acceptable accuracy for breast volume measurements, better spatial interpretation of the anatomical area to be operated on (due to lack of chest deformation), non-invasiveness, and good patient tolerance. After this preliminary study and further development, we believe that 3D body surface scanning could provide better preoperative planning and postoperative control in everyday clinical practice.

Adult↗
PubMed2006

Impaired cardiac autonomic nervous activity predicts sudden cardiac death in patients with operated and unoperated congenital cardiac disease.

OBJECTIVES: Sudden cardiac death is a leading cause of mortality in patients with congenital cardiac disease after surgical correction and is potentially preventable. The identification of patients at risk is therefore of major interest. We sought to assess the prognostic value of impaired cardiac autonomic nervous activity in patients with congenital cardiac disease. METHODS: Forty-three consecutive patients with congenital cardiac disease were included in this prospective study. Parameters of heart rate turbulence and heart rate variability were calculated from Holter electrocardiograms. In addition, serum brain natriuretic peptide levels were measured. A combined end point of sudden cardiac death or nearly missed sudden cardiac death was used. RESULTS: During a mean follow up of 27 +/- 12.7 months, 5 patients died, and another 2 were successfully resuscitated. On univariate analysis, both brain natriuretic peptide levels and parameters of heart rate variability and heart rate turbulence were associated with impaired prognosis. On multivariate analysis, pathologic heart rate turbulence was found to be the strongest independent risk stratifier (hazard ratio, 61.5; P < .001). CONCLUSIONS: Impaired cardiac autonomic nervous activity is associated with an increased risk of sudden cardiac death in congenital cardiac disease. Our results suggest that heart rate turbulence might be superior to established markers of cardiac autonomic dysfunction, such as heart rate variability. The combined use of heart rate turbulence, heart rate variability, and markers of neurohormonal activation, such as brain natriuretic peptide, might further improve the prognostic value.

Adult↗
PubMed2006

Real-time quantitative RT-PCR shows variable, assay-dependent sensitivity to formalin fixation: implications for direct comparison of transcript levels in paraffin-embedded tissues.

Real-time quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) is a versatile tool for precise quantification of gene expression. Formalin-fixed and paraffin-embedded (FFPE) tissue is well suited for qRT-PCR, if RNA extraction is optimized and small amplicon sizes are used. However, little is known whether individual assays may show variable sensitivity to fixation. This is of great importance, if a direct comparison of different transcripts is performed within the same sample, such as for mRNA splice variants. We established a cell culture model to test for and quantify differences in performance of individual qRT-PCR assays on FFPE as compared with fresh material, using TaqMan methodology. RNA was isolated from 7 different cell lines either directly or after preparation of a FFPE cell block. RNA from both sources was reverse transcribed and gene expression quantified using 13 different TaqMan assays. All assays allowed highly reproducible target quantification, using both fresh and FFPE-derived cDNA. The 13 assays showed an average Ct difference of 3.2 between fresh and FFPE cells, if identical amounts of cDNA were used as template. However, the Ct shifts varied from 1.8 to 5.1 for individual assays, indicating variable resistance to fixation. These Ct shift differences were statistically highly significant in 27/78 (35%) of all possible combinations of assays. Because the Ct shift remained constant for each assay, they could be used for calculation of correction factors which rendered FFPE-derived expression data highly comparable to those obtained from fresh material, and as a consequence among each other. Thus, a standardized assessment of qRT-PCR assay efficiencies in FFPE allows for precise intraindividual comparison of mRNA species, such as splice variants with different biologic functions, in archival tissues.

Biological Specimen Banks↗
PubMed2006

Comparison of different radiography systems in an experimental study for detection of forearm fractures and evaluation of the Müller-AO and Frykman classification for distal radius fractures.

OBJECTIVES: We sought to compare the diagnostic performance of screen-film radiography, storage-phosphor radiography, and a flat-panel detector system in detecting forearm fractures and to classify distal radius fractures according to the Müller-AO and Frykman classifications compared with the true extent, depicted by anatomic preparation. MATERIALS AND METHODS: A total of 71 cadaver arms were fractured in a material testing machine creating different fractures of the radius and ulna as well as of the carpal bones. Radiographs of the complete forearm were evaluated by 3 radiologists, and anatomic preparation was used as standard of reference in a receiver operating curve analysis. RESULTS: The highest diagnostic performance was obtained for the detection of distal radius fractures with area under the receiver operating curve (AUC) values of 0.959 for screen-film radiography, 0.966 for storage-phosphor radiography, and 0.971 for the flat-panel detector system (P > 0.05). Exact classification was slightly better for the Frykman (kappa values of 0.457-0.478) compared with the Müller-AO classification (kappa values of 0.404-0.447), but agreement can be considered as moderate for both classifications. CONCLUSIONS: The 3 imaging systems showed a comparable diagnostic performance in detecting forearm fractures. A high diagnostic performance was demonstrated for distal radius fractures and conventional radiography can be routinely performed for fracture detection. However, compared with anatomic preparation, depiction of the true extent of distal radius fractures was limited and the severity of distal radius fractures tends to be underestimated.

Area Under Curve↗
PubMed2006

New aspects of breast volume measurement using 3-dimensional surface imaging.

Precise and objective calculation of breast volume is helpful to evaluate the aesthetic result of breast surgery, but traditional methods are unsatisfactory. Three-dimensional (3D) scanning of the body surface allows reproducible and objective assessment of the complex breast region but requires further investigation before clinical application. The main goal of this study was to investigate the precision and accuracy of breast volume measurement using 3D body scanning. Five independent observers standardized the 3D scanning method using 2 dummy models (n = 200) and examined its applicability with 6 test subjects and 10 clinical patients (n = 2220). Breast volume measurements obtained with the 3D-scanner technology were compared with reference measurements obtained from test subjects through nuclear magnetic resonance imaging. The mean deviation of the breast volume measurements of 1 test subject by all observers, expressed as percentage of volume, was 2.86 +/- 0.98, significantly higher than the deviation for the dummy models, 1.65 +/- 0.42 (P < 0.001). With respect to all clinical patients, the mean measurement precision obtained preoperatively was less precise than that obtained postoperatively (3.31 +/- 1.02 versus 1.66 +/- 0.49, respectively). Interobserver differences in measurement precision were not statistically significant. The mean breast volumes obtained by nuclear magnetic resonance imaging (441.42 +/- 137.05 mL) and 3D scanning (452.51 +/- 141.88 mL) significantly correlated (r = 0.995, P < 0.001). Breast volume measurement with 3D surface imaging represents a sufficiently precise and accurate method to guarantee objective and exact recording.

Breast↗
PubMed2006

Effect of ozone on oral cells compared with established antimicrobials.

Ozone has been proposed as an alternative antiseptic agent in dentistry based on reports of its antimicrobial effects in both gaseous and aqueous forms. This study investigated whether gaseous ozone (4 x 10(6) microg m(-3)) and aqueous ozone (1.25-20 microg ml(-1)) exert any cytotoxic effects on human oral epithelial (BHY) cells and gingival fibroblast (HGF-1) cells compared with established antiseptics [chlorhexidine digluconate (CHX) 2%, 0.2%; sodium hypochlorite (NaOCl) 5.25%, 2.25%; hydrogen peroxide (H(2)O(2)) 3%], over a time of 1 min, and compared with the antibiotic, metronidazole, over 24 h. Cell counts, metabolic activity, Sp-1 binding, actin levels, and apoptosis were evaluated. Ozone gas was found to have toxic effects on both cell types. Essentially no cytotoxic signs were observed for aqueous ozone. CHX (2%, 0.2%) was highly toxic to BHY cells, and slightly (2%) and non-toxic (0.2%) to HGF-1 cells. NaOCl and H(2)O(2) resulted in markedly reduced cell viability (BHY, HGF-1), whereas metronidazole displayed mild toxicity only to BHY cells. Taken together, aqueous ozone revealed the highest level of biocompatibility of the tested antiseptics.

Analysis of Variance↗
PubMed2006

The long-term effect of sevoflurane on neuronal cell damage and expression of apoptotic factors after cerebral ischemia and reperfusion in rats.

We investigated the long-term effects of sevoflurane on histopathologic injury and key proteins of apoptosis in a rat hemispheric ischemia/reperfusion model. Sixty-four male Sprague-Dawley rats were randomly assigned to Group 1 (fentanyl and N2O/O2; control) and Group 2 (2.0 vol% sevoflurane and O2/air). Ischemia (45 min) was produced by unilateral common carotid artery occlusion plus hemorrhagic hypotension (mean arterial blood pressure 40 mm Hg). Animals were killed after 1, 3, 7, and 28 days. In hematoxylin and eosin-stained brain sections eosinophilic hippocampal neurons were counted. Activated caspase-3 and the apoptosis-regulating proteins Bax, Bcl-2, Mdm-2, and p53 were analyzed by immunostaining. No eosinophilic neurons were detected in sevoflurane-anesthetized rats over time, whereas 9%-38% of the hippocampal neurons were eosinophilic (days 1-28) in control animals. On days 1 and 3, the concentration of Bax was 140%-200% larger in fentanyl/N2O-anesthetized animals compared with sevoflurane. Bcl-2 was 100% less in control animals during the first 3 days. Activated caspase-3 was detected in neurons of both groups (0.75%-2.2%). These data support a sustained neuroprotective potency of sevoflurane related to reduced eosinophilic injury after cerebral ischemia/reperfusion.

Anesthetics, Inhalation↗
PubMed2006

The effect of electroencephalogram-targeted high- and low-dose propofol infusion on histopathological damage after traumatic brain injury in the rat.

BACKGROUND: Propofol is commonly used to sedate patients after traumatic brain injury. However, the dose-dependent neuroprotective effects of propofol after head trauma are unknown. We compared histopathological damage after 6 h of electroencephalogram-targeted high- and low-dose propofol infusion in rats subjected to controlled cortical impact (CCI). METHODS: Animals were randomly assigned to CCI/propofol with electroencephalogram burst-suppression-ratio 1%-5% (CCI/lowprop), CCI/propofol with burst-suppression-ratio 30%-40% (CCI/highprop), control group CCI/1.0 vol % halothane (CCI/halo), or sham group with halothane anesthesia (SHAM/halo). Brain slices were stained with kresyl violet (KV) and hematoxylin/eosin (HE) to evaluate lesion volume, number of eosinophilic cells, and activation of caspase-3 in the hippocampus. RESULTS: Lesion volume (mm3) and number of eosinophilic cells in the hippocampus did not differ significantly [lesion volumes: CCI/lowprop 31.55 +/- 14.66 (KV) and 53.77 +/- 8.62 (HE); CCI/highprop 33.81 +/- 10.57 (KV) and 52.30 +/- 11.55 (HE); CCI/halo 36.42 +/- 17.06 (KV) and 57.95 +/- 8.49 (HE)]. Activation of caspase-3 occurred in the ipsilateral hippocampus in all CCI-groups. CONCLUSION: Despite different levels of cortical neuronal function, there were no relevant differences in the short-term histopathological damage. These results challenge the view that the neuroprotective effect of propofol relates to the suppression of cerebral metabolic demand.

Animals↗
PubMed2005

Detection of consciousness by electroencephalogram and auditory evoked potentials.

BACKGROUND: A set of electroencephalographic and auditory evoked potential (AEP) parameters should be identified that allows separation of consciousness from unconsciousness (reflected by responsiveness/unresponsiveness to command). METHODS: Forty unpremedicated patients received anesthesia with remifentanil and either sevoflurane or propofol. With remifentanil infusion (0.2 microg . kg . min), patients were asked every 30 s to squeeze the investigator's hand. Sevoflurane or propofol was given until loss of consciousness. After intubation, propofol or sevoflurane was stopped until patients followed the command (return of consciousness). Thereafter, propofol or sevoflurane was started again (loss of consciousness), and surgery was performed. Return of consciousness was observed after surgery. The electroencephalogram and AEP from immediately before and after the transitions were selected. Logistic regression was calculated to identify models for the separation between consciousness and unconsciousness. For the top 10 models, 1,000-fold cross-validation was performed. Backward variable selection was applied to identify a minimal model. Prediction probability was calculated. The digitized electroencephalogram was replayed, and the Bispectral Index was measured and accordingly analyzed. RESULTS: The best full model (prediction probability 0.89) contained 15 AEP and 4 electroencephalographic parameters. The best minimal model (prediction probability 0.87) contained 2 AEP and 2 electroencephalographic parameters (median frequency of the amplitude spectrum from 8-30 Hz and approximate entropy). The prediction probability of the Bispectral Index was 0.737. CONCLUSIONS: A combination of electroencephalographic and AEP parameters can be used to differentiate between consciousness and unconsciousness even in a very challenging data set. The minimal model contains a combination of AEP and electroencephalographic parameters and has a higher prediction probability than Bispectral Index for the separation between consciousness and unconsciousness.

Adult↗
PubMed2005

Different relation between 24-h blood pressure and distensibility at different peripheral arteries. Data from the European Lacidipine Study on Atherosclerosis (ELSA).

INTRODUCTION: The European Lacidipine Study on Atherosclerosis (ELSA) has been planned to investigate the effect of reduction in office and ambulatory blood pressure by lacidipine versus atenolol on carotid artery wall thickness in mild to moderate essential hypertensive patients with no metabolic abnormalities. One prespecified sub-study of ELSA focused on measurements of arterial distensibility in the carotid as well as in the radial artery to determine the relationship of functional arterial properties with office versus ambulatory blood pressure (BP) values as well as the correspondence between functional and structural arterial alterations. METHODS: The sub-study was conducted on 124 patients recruited in four centres (Monza-Milan, Paris, Grenoble and Glasgow). BP was measured both by a mercury sphygmomanometer and by 24-h ambulatory monitoring. Common carotid artery wall thickness was measured by certified sonographers as described in the main study. Common carotid and radial artery distensibility were obtained by echotracking techniques, which allowed to relate changes in arterial diameter with systo-diastolic BP changes. RESULTS: Carotid artery wall distensibility showed (1) a negative correlation with office and more so 24-h average systolic BP (r = -0.45 and -0.58, P < 0.008 and 0.001) but not with office or 24-h diastolic BP) and (2) a negative correlation with the corresponding wall thickness (r = -0.47, P < 0.005). In contrast, at the radial artery level distensibility and thickness showed no correlation with each other and with BP. Carotid (but not radial) artery distensibility also correlated with ambulatory systolic BP variability but the correlation was lost after adjustment for age and mean BP values. CONCLUSION: These data suggest that stiffening of large elastic artery is reflected more by ambulatory than office BP elevations, systolic BP being much more important than diastolic. Alterations of large elastic arteries function is related to structural wall changes. Functional and structural properties of middle-size muscle arteries are independent of BP.

Antihypertensive Agents↗
PubMed2005

Quality control of B-mode ultrasonic measurement of carotid artery intima-media thickness: the European Lacidipine Study on Atherosclerosis.

BACKGROUND: The European Lacidipine Study of Atherosclerosis (ELSA) was a prospective, randomized, double-blind, multinational interventional trial using B-mode ultrasound measurement of carotid intima-media thickness (IMT) in 2259 hypertensive individuals. ELSA showed that 4-year treatment with the calcium antagonist, lacidipine, significantly slowed down progression of carotid atherosclerosis as compared with treatment with the beta-blocker, atenolol. OBJECTIVE: To report data on cross-sectional and longitudinal quality control of the ultrasound measurements implemented throughout ELSA. METHODS: Patients underwent scans at baseline and at each annual visit. All endpoints were measured while the study was in progress (initial measurements). In addition to the cross-sectional quality control procedures, a longitudinal quality control procedure of re-reading 250 baseline scans at yearly intervals was implemented, to control possible reader drift. After the study had been completed, the primary endpoint was measured again under the same condition of cross-sectional quality control. RESULTS: Cross-sectional quality control data showed high reliability for all endpoints at all time points except for single maximum IMT (Tmax) and internal carotid IMT. Within-reader reliability was constantly better than between-reader reliability but, for the primary endpoint, between-reader reliability remained excellent. Initial and longitudinal quality control measurements showed a time trend toward lower IMT values. After application of a correction factor calculated from longitudinal quality control, all initial measurements no longer decreased with time, and the corrected IMT measurements were reasonably similar to those made after completion of the study. CONCLUSION: For long-term epidemiological studies and clinical trials, both cross-sectional and longitudinal quality control are critical to the reliability of measurements. In order to evaluate the absolute change in IMT and interpret study results without bias, both must be implemented.

Carotid Arteries↗
PubMed2005

Chest radiography with a digital flat-panel detector: experimental receiver operating characteristic analysis.

PURPOSE: To evaluate the influence of different detector radiation doses and peak kilovoltage settings on diagnostic performance and radiation dose at posteroanterior (PA) chest radiography performed with an amorphous silicon flat-panel detector (FPD). MATERIALS AND METHODS: All examinations were performed by using a digital FPD. PA chest radiographs of an anthropomorphic chest phantom were obtained with detector radiation doses of 2.50 microGy (system speed, 400), 1.56 microGy (speed, 640), and 1.25 microGy (speed, 800) and with peak kilovoltage values of 100, 120, and 140 kVp. Four types of simulated lesions-nodules of different sizes, polylobulated lesions, interstitial-nodular lesions, and interstitial-reticular lesions-were superimposed on the phantom. After four radiologists assessed all of the images, receiver operating characteristics analysis was performed. In addition, the entrance surface dose was measured and the effective dose was calculated. RESULTS: Reduced detector dose led to significantly decreased diagnostic performance in overall lesion detection (P <.05). However, over pulmonary areas only, this effect could not be seen. With use of the same kilovoltage values, reducing the detector dose, even to 1.25 microGy (speed, 800), did not lead to significantly decreased lesion detectability. In terms of diagnostic performance and effective dose, 120 kVp was the most effective. CONCLUSION: Standard PA chest radiographs should still be acquired at a detector dose of 2.50 microGy (speed, 400) with 120 kVp to yield the highest diagnostic performance. However, when the present analysis was focused on the lung fields only, no significant loss in diagnostic performance could be demonstrated, even after a 50% reduction in radiation dose.

Observer Variation↗
PubMed2004

Influence of propofol on neuronal damage and apoptotic factors after incomplete cerebral ischemia and reperfusion in rats: a long-term observation.

BACKGROUND: Propofol reduces neuronal damage from cerebral ischemia when investigated for less than 8 postischemic days. This study investigates the long-term effects of propofol on neuronal damage and apoptosis-related proteins after cerebral ischemia and reperfusion. METHODS: Male Sprague-Dawley rats were randomly assigned as follows: group 1 (n = 32, control): fentanyl and nitrous oxide-oxygen; group 2 (n = 32, propofol): propofol and oxygen-air. Ischemia (45 min) was induced by carotid artery occlusion and hemorrhagic hypotension. Pericranial temperature and arterial blood gases were maintained constant. After 1, 3, 7, and 28 postischemic days, brains were removed, frozen, and sliced. Hippocampal eosinophilic cells were counted. The amount of apoptosis-related proteins Bax, p53, Bcl-2, and Mdm-2 and neurons positive for activated caspase-3 were analyzed. RESULTS: In propofol-anesthetized rats, no eosinophilic neurons were detected, whereas in control animals, 16-54% of hippocampal neurons were eosinophilic (days 1-28). In control animals, the concentration of Bax was 70-200% higher after cerebral ischemia compared with that in animals receiving propofol over time. Bcl-2 was 50% lower in control animals compared with propofol-anesthetized rats during the first 3 days. In both groups, a maximal 3% of the hippocampal neurons were positive for activated caspase-3. CONCLUSIONS: These data show sustained neuroprotection with propofol. This relates to reduced eosinophilic and apoptotic injury. Activated caspase-3-dependent apoptotic pathways were not affected by propofol. This suggests the presence of activated caspase-3-independent apoptotic pathways.

Animals↗
PubMed2004

Absolute and relative changes in carotid intima-media thickness and atherosclerotic plaques during long-term antihypertensive treatment: further results of the European Lacidipine Study on Atherosclerosis (ELSA).

BACKGROUND: In ELSA, a randomized, double-blind trial in 2334 hypertensives, 4-year antihypertensive treatment with lacidipine slowed down progression of carotid atherosclerosis significantly more than atenolol treatment. To avoid bias, the primary outcome was measured blindly at study-end on a randomized sequence of scans, but measurements were limited to the four far walls of common carotids and bifurcations (CBMmax) and to one of each couple of duplicate scans recorded yearly. OBJECTIVES AND METHODS: Secondary outcomes included measurements made on all duplicate scans of both near and far walls, not only of common carotids and bifurcations, but also of internal carotids (12 walls). These measurements were made blindly during the 4-year study, shortly after recording. To avoid possible readers' drift or bias, 250 duplicate baseline scans were re-read at yearly intervals (longitudinal on-line quality control) and a correction factor calculated. RESULTS: Measurements during the 4-year study showed a trend toward decreased values, with the lacidipine effect significantly greater than the atenolol one. A trend toward lower values was also observed in the longitudinal quality control of baseline scans. After applying a correction factor calculated from this longitudinal control, all measurements no longer decreased with time, but significantly increased, with progression being significantly smaller in lacidipine than in atenolol patients. Corrected values were quite similar to those calculated on measurements carried out at study-end. CONCLUSION: The relative benefit of lacidipine over atenolol could be measured precisely by reading scans either during the study or at study-end. However, absolute treatment-related changes (progression versus regression) cannot safely be judged by readings made during a long-term study, unless a longitudinal quality control of readings is performed.

Aged↗