Biomedical subjects

Edgar Brunner

Publications and source records attributed to Edgar Brunner.

12 recordsLinked to original sources

PubMed2006

Effect of bleaching on subsurface micro-hardness of composite and a polyacid modified composite.

OBJECTIVE: To investigate the influence of different bleaching techniques on subsurface physical properties of composite and polyacid modified composite tested via determination of micro-hardness. METHODS: Specimens of Tetric Flow, Tetric EvoCeram and Compoglass were light cured (2.5mm thickness) and stored in artificial saliva for 2 weeks (n=12/group). The samples were only removed for application of the following bleaching agents in a humid atmosphere: Either Vivastyle (1h/d), Whitestrips (30min/d), sodium-perborate-water mixture (once for 72h), Simply White (1h/d), or Opalescence XtraBoost (1st and 5th day for 15min) were applied on the surfaces of the samples. Untreated specimens served as negative controls, samples treated with ethyl alcohol for 1h acted as positive controls. After the bleaching period, samples were cross-sectioned and the micro-hardness (Knoop) of different subsurface levels (0.1mm-2.0mm) was determined. RESULTS: All bleaching techniques significantly reduced the Knoop-hardness of the restoratives compared to untreated controls. Thereby, bleaching significantly affected not only superficial but also the deep layers of the specimens: in superficial layers (0.1mm, 0.2mm) lowest micro-hardness values amounted to 69.5% and 76.3% of the respective untreated controls (Compoglass/Vivastyle). In deeper subsurface levels, the lowest hardness was observed with Opalescence/Tetric EvoCeram (0.3mm: 78.3%; 0.4mm: 80%; 0.5mm: 80.5%; 1.0mm: 84.2%; 2.0mm: 84.4%). SIGNIFICANCE: Bleaching with the tested bleaching agents softens the adhesive restorative materials examined. Due to the fact that subsurface layers are also affected, polishing of the surface may not suffice for re-establishing the physical properties of the surface of the fillings.

Borates↗

PubMed2005

In situ background estimation in quantitative fluorescence imaging.

Fluorescence imaging of bulk-stained tissue is a popular technique for monitoring the activities in a large population of cells. However, a precise quantification of such experiments is often compromised by an ambiguity of background estimation. Although, in single-cell-staining experiments, background can be measured from a neighboring nonstained region, such a region often does not exist in bulk-stained tissue. Here we describe a novel method that overcomes this problem. In contrast to previous methods, we determined the background of a given region of interest (ROI) using the information contained in the temporal dynamics of its individual pixels. Since no information outside the ROI is needed, the method can be used regardless of the staining profile in the surrounding tissue. Moreover, we extend the method to deal with background inhomogeneities within a single ROI, a problem not yet solved by any of the currently available tools. We performed computer simulations to demonstrate the accuracy of our method and give example applications in ratiometric calcium imaging of bulk-stained olfactory bulb slices. Converting the fluorescence signals into [Ca2+] gives resting values consistent with earlier single-cell staining results, and odorant-induced [Ca2+] transients can be quantitatively compared in different cells. Using these examples we show that inaccurate background subtraction introduces large errors (easily in the range of 100%) in the assessment of both resting [Ca2+] and [Ca2+] dynamics. The proposed method allows us to avoid such errors.

Algorithms↗

PubMed2005

A novel ultrasonographic synovitis scoring system suitable for analyzing finger joint inflammation in rheumatoid arthritis.

OBJECTIVE: To develop an ultrasonographic (US) synovitis scoring system suitable for evaluation of finger joint inflammation in patients with active rheumatoid arthritis (RA) and to compare semiquantitative US scoring with quantitative US measurements. METHODS: US was performed at the palmar and dorsal sides of the second through fifth metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joints in 10 healthy subjects and in the clinically more affected hand in 46 RA patients. Ten patients additionally underwent magnetic resonance imaging (MRI). Synovitis was measured, standardized, and scored according to a semiquantitative method. The 2 methods (semiquantitative US scoring, quantitative US) were compared and statistical cutoffs were identified using receiver operating characteristic (ROC) curve analysis. MRI results were compared with semiquantitative US scoring and quantitative US results. The optimal US scoring method from 6 joint combinations was identified (ROC curve analysis). RESULTS: Synovitis was most frequently detected in the palmar proximal area (86% of affected joints). We found no significant differences between individual PIP joints or between individual MCP joints, indicating that all fingers within each of these joint groups should be treated equally for statistical calculations, although each joint group as a whole should be treated separately. The optimal cutoff point to distinguish between "health" and "pathology" was 0.6 mm both for MCP joints (sensitivity 94%, specificity 89%) and for PIP joints (sensitivity 90%, specificity 88%). There was no significant difference between semiquantitative US scores and quantitative US measurements. The best results for joint combinations were achieved using the "sum of 4 fingers" (second through fifth MCP and PIP joints) and "sum of 3 fingers" (second through fourth MCP and PIP joints) methods. Comparison of MRI results with semiquantitative US scores revealed high concordance. CONCLUSION: US evaluation of finger joint synovitis can be considerably simplified by focusing on the palmar side and by applying semiquantitative grading instead of quantitative measurements. For evaluation of treatment efficacy based on synovitis in RA patients, we recommend using the "sum of 3 fingers" method in longitudinal trials.

Adolescent↗

PubMed2005

Chlamydia trachomatis modulates expression of tumor suppressor gene caveolin-1 and oncogene C-myc in the transformation zone of non-neoplastic cervical tissue.

OBJECTIVES: The obligate intracellular bacterium Chlamydia trachomatis is frequently found in association with benign proliferative, pre-neoplastic and malignant changes in cervical epithelium. The present study addresses the possible role of C. trachomatis infection of the uterine cervix in modulating human cancer gene expression. METHODS: RNA was extracted from both C. trachomatis infected and non-infected human fibroblast cultures treated with ITFgamma. The extracted RNA was used for cDNA microarrays carrying 33,000 human genes to detect abnormal gene expression induced by Chlamydia. Forty specimens of cervix dissected from the transformation zone had previously tested negative for HPV and positive for C. trachomatis by standard DNA PCR (20). These samples were subjected to RT-PCR to detect the expression of the abnormal genes induced by Chlamydia infection. RESULTS: The ITFgamma-induced, non-replicative Chlamydia-infected fibroblast cultures showed significant modulation of gene expression. The cultures showed a 2-fold decrease in the expression of the gene coding for the tumor suppressor caveolin-1, and increased expression of the oncogene C-myc, a promoter of cervical carcinogenesis. In tissues from the Chlamydia-infected cervical transformation zone, real-time RT-PCR demonstrated a highly significant average 4.7-fold reduction of caveolin-1 mRNA (P < or = 0.0001) and an average 2.1-fold increase in C-myc (P < 0.05). CONCLUSIONS: Human ITFgamma-treated fibroblasts as well as non-neoplastic cervical tissues responded to C. trachomatis with a strong down-regulation of caveolin-1 mRNA and a light up-regulation of C-myc mRNA. These changes were independent of the HPV high-risk types. This study reveals possible mechanisms by which C. trachomatis infection may contribute to neoplastic changes in the transformation of uterine cervix. These possible mechanisms require further evaluation.

Caveolin 1↗

PubMed2005

Nonparametric methods for analysing the accuracy of diagnostic tests with multiple readers.

The evaluation of diagnostic agents or imaging procedures is governed by the same scientific and regulatory rules as that of other medical products. Receiver operating characteristic (ROC) curves, and especially the area under these ROC curves, are indices for the accuracy of a diagnostic test for continuous as well as ordinal data. The methodology of multivariate rank statistics for the nonparametric Behrens-Fisher problem is used to evaluate the accuracy of a diagnostic test in a complex factorial design with repeated measurements. Hypotheses are formulated by means of relative treatment effects and are tested by a multivariate extension of the Mann-Whitney statistic in a heteroscedastic model. The application of this method is demonstrated by the analysis of a data set from a diagnostic clinical trial.

Biometry↗

PubMed2004

Prostaglandin D synthase (beta-trace) in healthy human sleep.

STUDY OBJECTIVES: The prostaglandin D system plays an important role in animal sleep. In humans, alterations in the prostaglandin D system have been found in diseases exhibiting sleep disturbances as a prominent symptom, such as trypanosoma infection, systemic mastocytosis, bacterial meningitis, major depression, or obstructive sleep apnea. Assessment of this system's activity in relation to human physiologic sleep was the target of the present study. DESIGN: Serum concentrations of lipocalin-type prostaglandin D synthase (L-PGDS, former beta-trace), and plasma levels of the pineal hormone melatonin were measured in 20 healthy humans (10 women, 10 men; aged: 23.3 +/- 2.39 years) at 4-hour intervals over a period of 5 days and nights, which included physiologic sleep, rapid eye movement sleep deprivation, and total sleep deprivation. In addition, the serum L-PGDS and plasma melatonin levels of 6 subjects were determined under conditions of bright white (10,000 lux) or dark red light (< 50 lux) in a crossover design during total sleep deprivation. Nocturnal blood sampling was performed by a through-the-wall tube system. L-PGDS was measured by an automated immunonephelometric assay, and melatonin was analyzed by direct radioimmunoassay. RESULTS: Serum L-PGDS concentrations showed marked time-dependent changes with evening increases and the highest values at night (P < .0005). This nocturnal increase was suppressed during total sleep deprivation (P < .05), independent of external light conditions and melatonin secretion. Rapid eye movement sleep deprivation had no impact on circulating L-PGDS levels. CONCLUSIONS: The circadian L-PGDS pattern and its suppression by total sleep deprivation indicate an interaction of the prostaglandin D system and human sleep regulation. L-PGDS measurements may well provide new insights into physiologic and pathologic sleep regulation in humans.

Adult↗

PubMed2004

Growth behavior, matrix production, and gene expression of human osteoblasts in defined cylindrical titanium channels.

The purpose of the current study was to investigate the effect of different diameters of cylindrical titanium channels on human osteoblasts. Titanium samples having continuous drill channels with diameters of 300, 400, 500, 600, and 1000 microm were put into osteoblast cell cultures that were isolated from 12 adult human trauma patients. Cell migration into the drill channels was investigated by transmitted-light microscopy. The DNA content in the drill channels was measured photometrically, collagen type I production was analyzed by enzyme-linked immunosorbent assay (ELISA) and osteocalcin gene expression by reverse transcriptase-polymerase chain reaction (RT-PCR). Formation of mineralized tissue was assessed by microradiographs of histological sections. Within 20 days, cells grew an average of 838 microm (+/-128 microm) into the drill channels with a diameter of 600 microm and were significantly faster (p < 0.05) than in all other channels. Cells produced significantly more osteocalcin messenger RNA (mRNA) in 600-microm channels (p < 0.05) than they did in 1000-microm channels and demonstrated the highest osteogenic differentiation. The channel diameter did not influence collagen type I production. The highest cell density was found in 300-microm channels (p < 0.05). The DNA content of the channels linearly decreased with increasing channel diameters. After 40 days of culture, the proportion of mineralized tissue at the mouth section amounted to 6% in 300-microm channels and to 9-11% in 400-600-microm channels. In 1000-microm channels, only traces of mineralization were detected. Our data suggest that the diameter of cylindrical titanium channels has a significant effect on migration, gene expression, and mineralization of human osteoblasts.

Biocompatible Materials↗

PubMed2004

Preserved vasopressin response to osmostimulation despite decreased basal vasopressin levels in long-term abstinent alcoholics.

BACKGROUND: Basal arginine vasopressin (AVP) plasma levels in alcoholic patients are persistently decreased over months of controlled alcohol abstinence. As a potential explanation of this phenomenon, a reduction of AVP immunoreactive neurons was described in the hypothalamus of alcohol-dependent humans and rodents. This study was therefore designed to examine whether long-term abstinent alcoholics have a compromised response of AVP to osmostimulation. METHODS: Fifteen male alcoholics, aged 42 +/- 2 years, were examined (1) over 12 months of strictly controlled abstinence (longitudinal study) and (2) during an osmostimulation test (5% NaCl infusion at 0.06 ml/kg/min over 2 hr) and were compared with 15 healthy male subjects, aged 41 +/- 2 years. AVP and routine laboratory parameters, including electrolytes and osmolality, were measured. RESULTS: Starting from lower basal concentrations, alcoholics showed increases similar to those of controls in AVP and plasma osmolality after osmostimulation. The first sensation of thirst was announced significantly later by alcoholics than by controls. Twenty-hour-posttest urine volume and sodium excretion were reduced in alcoholics compared with controls. CONCLUSIONS: Despite their persistently decreased basal AVP plasma levels, long-term abstinent alcoholics have a well preserved AVP response to osmostimulation. This finding indicates a peripheral suppression of AVP levels that is most likely due to a regulatory set-point shift toward hypotonic hyperhydration, rather than to a reduced central capacity of AVP secretion.

Adult↗

PubMed2004

Efficient two-sample designs for microarray experiments with biological replications.

In the last years, biostatistical research has begun to apply linear models and design theory to develop efficient experimental designs and analysis tools for gene expression microarray data. With two-colour microarrays, direct comparisons of RNA-targets are possible and lead to incomplete block designs. In this setting, efficient designs for simple and factorial microarray experiments have mainly been proposed for technical replicates. But for biological replicates, which are crucial to obtain inference that can be generalised to a biological population, this question has only been discussed recently and is not fully solved yet. In this paper, we propose efficient designs for independent two-sample experiments using two-colour microarrays enabling biologists to measure their biological random samples in an efficient manner to draw generalisable conclusions. We give advice for experimental situations with differing group sizes and show the impact of different designs on the variance and degrees of freedom of the test statistics. The designs proposed in this paper can be evaluated using SAS PROC MIXED or S+/R lme.

Data Interpretation, Statistical↗

PubMed2003

Association of ADHD and conduct disorder--brain electrical evidence for the existence of a distinct subtype.

BACKGROUND: To evaluate the impact of psychopathological comorbidity with oppositional defiant/conduct disorder (ODD/CD) on brain electrical correlates in children with attention deficit hyperactivity disorder (ADHD) and to study the pathophysiological background of comorbidity of ADHD+ODD/CD. METHOD: Event-related potentials (ERPs) were recorded during a cued continuous performance test (CPT-A-X) in children (aged 8 to 14 years) with ICD-10 diagnoses of either hyperkinetic disorder (HD; n = 15), hyperkinetic conduct disorder (HCD; n = 16), or ODD/CD (n = 15) and normal children (n = 18). HD/HCD diagnoses in all children were fully concordant with the DSM-IV diagnosis of ADHD-combined type. ERP-microstates, i.e., time segments with stable brain electrical map topography were identified by adaptive segmentation. Their characteristic parameters and behavioral measures were further analyzed. RESULTS: Children with HD but not comorbid children showed slower and more variable reaction times compared to control children. Children with HD and ODD/CD-only but not comorbid children displayed reduced P3a amplitudes to cues and certain distractors (distractor-X) linked to attentional orienting. Correspondingly, global field power of the cue-CNV microstate related to anticipation and preparation was reduced in HD but not in HCD. Topographical alterations of the HD occurred already in the cue-P2/N2 microstate. In sum, the comorbid group was less deviant than both the HD-group and the ODD/CD-group. CONCLUSIONS: The findings suggest that HD children (ADHD-combined type without ODD/CD) suffer from a more general deficit (e.g., suboptimal energetical state regulation) including deficits of attentional orienting and response preparation than just a responseinhibitory deficit, backing the hypothesis of an involvement of a dysregulation of the central noradrenergic networks. The results contradict the hypothesis that ADHD+ODD/CD represents an additive co-occurrence of ADHD and ODD/CD and strongly suggest that it represents a separate pathological entity as considered in the ICD-10 classification system, which differs from both HD and ODD/CD-only.

Adolescent↗

PubMed2002

Effects of cerebrovascular challenges on plasma endothelin.

Plasma endothelin elevations have been associated with cerebrovascular pathology. Mechanisms of stimulation, however, are unknown. Therefore, in healthy subjects a marked physiological cerebrovascular response was experimentally provoked by hypercapnia, hypocapnia, and alternating capneic conditions. During these challenges plasma immunoreactive-endothelin-1 (ir-ET-1) concentrations were determined using a radioimmunassay. Physiological effects were continuously recorded for pCO(2), cerebral blood flow velocity, pulse frequency, and arterial blood pressure. No alterations in plasma ET-1 levels were found upon any of the cerebrovascular stimuli. We conclude that massive cerebrovascular challenges in healthy individuals do not lead to high circulating ET-1 levels.

Adult↗

PubMedDate not supplied

Substantial decrease of psychiatric comorbidity in chronic alcoholics upon integrated outpatient treatment - results of a prospective study.

It is far from clear how comorbidity changes during alcoholism treatment. This study investigates: (1) the course of comorbid Axis I disorders in chronic alcoholics over 2 years of controlled abstinence in the outpatient long-term intensive therapy for alcoholics (OLITA) and (2) the effect of comorbid Axis I and II disorders in this group of patients on subsequent drinking outcome over a four-year follow-up. This prospective treatment study evaluates psychiatric variables of 89 severely affected chronic alcohol dependent patients on admission (t(1)), month 6 (t(2)), 12 (t(3)) and 24 (t(4)). Drinking outcomes have been analyzed from 1998 to 2002. On admission, 61.8% of the patients met criteria for a comorbid Axis I disorder, 63.2% for a comorbid personality disorder. Axis I disorders remit from t(1) (59.0% ill), t(2) (38.5%), t(3) (28.2%) to t(4) (12.8%) (p < 0.0001). Anxiety disorders remit more slowly from t(1) (43.6%) to t(3) (20.5%, p = 0.0086), whereas mood disorders remit early between t(1) (23.1%) and t(2) (5.1%, p = 0.0387) with a slight transient increase at t(3) (10.3%). During the four-year follow-up, the cumulative probability of not having relapsed amounts to 0.59. Two predictors have a strong negative impact on abstinence probability: number of inpatient detoxifications (p = 0.0013) and personality disorders (p = 0.0106). The present study demonstrates a striking remission of comorbid Axis I disorders upon abstinence during comprehensive long-term outpatient alcoholism treatment. The presence of an Axis II rather than an Axis I disorder on admission strongly predicts drinking outcome over a four-year follow-up.

Adult↗