Biomedical subjects
Publications and source records attributed to C Gärtner.
The accuracy, reliability, and reproducibility of the virtual articulator as applied in functional diagnostics are examined. Its potential in planning and simulating orthodontic treatment is also explored.
OBJECTIVES: The aim of this study was to evaluate in vitro the relationship between polymerization shrinkage and microleakage in dentin-bordered restorations. METHODS: Four light-cured restorative materials in combination with their respective dental bonding agents (DBA) were investigated: Tetric Ceram/Syntac classic (Vivadent), Solitaire/Gluma Solid bond (Heraeus Kulzer), Definite/Etch & Prime 3.0 (Degussa), Solitaire 2/Gluma Solid bond (Heraeus Kulzer). The chemically cured resin Degufill sc microhybrid (Degussa) in combination with ART Bond (Coltène) was also included. Polymerization shrinkage of the restorative materials was measured using three different methods (dilatometer, linometer, buoyancy method) and analyzed with ANOVA. For the determination of microleakage, caries-free human molars were embedded in acrylic resin and subsequently abraded with a wet abrasion machine to produce four level dentin surfaces. One hundred sixty cavities (3 mm diameter/1.5 mm deep) were randomly assigned to four groups of equal size. The groups were restored without (group 1 and 2) and with DBA (group 3 and 4), and either not subjected (group 1 and 3) or subjected (group 2 and 4) to 2000 cycles from 5-55 degrees C. Each group was further divided into five material subgroups of eight cavities each. Microleakage was determined using a dye penetration test assessed at depths of 200, 400 and 600 microm into the fillings. Data were analyzed with the Kruskal-Wallis and the Mann-Whitney test. RESULTS: All three methods of measuring polymerization shrinkage (PS) generated the same, statistically secured ranking for the four light-cured restorative materials: PS Definite < PS Tetric Ceram < PS Solitaire 2 < PS Solitaire. In the microleakage study, only a few statistically significant differences were observed. Etch & Prime 3.0/Definite in group 3 and Solid Bond/Solitaire 2 in group 4 tended to exhibit the least microleakage. Correlation coefficients between aggregated shrinkage and microleakage data were 0.3 for group 3 and -0.2 for group 4. SIGNIFICANCE: The results do not suggest any correlation between polymerization shrinkage and microleakage in dentin of direct adhesive restorations.
In this paper, we describe the fabrication technologies necessary for the production of polymer-based micro-fluidic devices. These technologies include hot embossing as a micro-structuring method as well as so-called back-end processes to complete the micro-devices. Applications such as capillary electrophoresis, micro-mixers and nanowell plates are presented.
A growing number of microsystem technology (MST) applications, particularly in the field of microfluidics with its applications in the life sciences, have a need for novel fabrication methods which account for substrates other than silicon or glass. We present in this paper an overview of existing polymer microfabrication technologies for microfluidic applications, namely replication methods such as hot embossing, injection molding and casting, and the technologies necessary to fabricate the molding masters. In addition, techniques such as laser ablation and layering techniques are examined. Methods for bonding and dicing of polymer materials, which are necessary for complete systems, are evaluated.
Palm oil carotenoids are a mixture of alpha- and beta-carotenes, which are used as food colorants. They may also be applied as a functional food ingredient because of the provitamin A activity of alpha- and beta-carotenes and their proposed beneficial roles in the prevention of chronic diseases. This paper discusses the results of an incomplete balanced crossover study with 69 healthy adult volunteers to compare palm oil carotenoids with synthetic beta-carotene in their efficacies to increase plasma levels of carotenoids. Four days of supplementation with natural palm oil carotenoids (7.6 mg/day of alpha-carotene, 11.9 mg/day of all-trans-beta-carotene, 7.5 mg/day of cis-beta-carotene) or synthetic beta-carotene (23.8 mg/day of all-trans-beta-carotene, 4.4 mg/day of cis-beta-carotene), added to a mixed meal, resulted in significant increases in plasma levels of the supplied carotenoids as compared to consumption of a low-carotenoid meal (i.e., 7.2-fold increase in alpha-carotene and 3.5-fold increase in all-trans-beta-carotene following palm oil carotenoids; 6.9-fold increase in all-trans beta-carotene following synthetic beta-carotene). As the carotenoid content differed between the treatments, the relative plasma responses were calculated per milligram of beta-carotene intake. These were similar for the two supplements, suggesting that the presence of alpha-carotene does not affect the bioavailability of beta-carotene from palm oil. It was concluded that 4 days of supplementation with palm oil carotenoids or synthetic beta-carotene improves the plasma beta-carotene status substantially, whereas alpha-carotene is additionally delivered by the palm oil supplement.
It has been suggested that carotenoids contribute to the inverse association between vegetable consumption and risk for coronary heart disease and cancer. However, there are indications that the bioavailability of beta-carotene from vegetables is less than previously thought. Therefore, it is of interest to explore whether the bioavailability of carotenoids from vegetables can be improved. We have reviewed data on the effect of vegetable processing on carotenoid bioavailability. Based on this analysis, we conclude that processing of vegetables by mechanical homogenization or heat treatment has the potential of increasing the bioavailability of carotenoids. Addition of fat during processing may also have an effect.
Lycopene bioavailability from a single dose of fresh tomatoes or tomato paste (23 mg lycopene) ingested together with 15 g corn oil was compared by analyzing carotenoid concentrations in the chylomicron fraction. The lycopene isomer pattern was the same in both fresh tomatoes and tomato paste. The triacylglycerol response in chylomicrons was not significantly different after both treatments. Ingestion of tomato paste was found to yield 2.5-fold higher total and all-trans-lycopene peak concentrations (P < 0.05 and P < 0.005, respectively) and 3.8-fold higher area under the curve (AUC) responses (P < 0.001) than ingestion of fresh tomatoes. The same was calculated for lycopene cis-isomers, but only the AUC response for the cis-isomers was significantly higher after ingestion of tomato paste (P < 0.005). No difference was observed in the alpha- and beta-carotene response. Thus, in humans, the bioavailability of lycopene is greater from tomato paste than from fresh tomatoes.
OBJECTIVE: This study was conducted to show vascularization of Schmorl's nodes with enhanced MR imaging and to correlate this finding with clinical complaints. MATERIALS AND METHODS: Retrospectively, 412 gadopentetate dimeglumine-enhanced MR imaging examinations of the lumbar and thoracic spine of 372 patients were reviewed for Schmorl's nodes, vascularization of Schmorl's nodes, and associated bone marrow edema. Sagittal T2-weighted spin-echo and unenhanced and enhanced T1-weighted spin-echo images with and without fat suppression were evaluated in symptomatic and asymptomatic patients. RESULTS: Of the 372 patients, 142 (38%) had 341 Schmorl's nodes. Gadopentetate dimeglumine-enhanced MR imaging revealed vascularized tissue in 30 Schmorl's nodes of 23 patients (mean age of patients, 53 years old). Associated bone marrow edema was found in nine of 30 vascularized Schmorl's nodes. The mean diameter (8.2 mm) of the nine vascularized Schmorl's nodes that were surrounded by bone marrow edema was significantly (p < .05) greater than the mean diameter (6.4 mm) of the 21 vascularized Schmorl's nodes that had no bone marrow edema. The vascularized Schmorl's nodes were significantly (p < .05) smaller in the seven asymptomatic patients (mean, 5.2 mm) than in the 23 patients with back pain (mean, 7.9 mm). We saw bone marrow edema adjacent to Schmorl's nodes less frequently in asymptomatic patients (one of seven) than in symptomatic patients (10 of 23). CONCLUSION: Vascularized Schmorl's nodes were larger and more frequently associated with bone marrow edema in patients with back pain than in asymptomatic patients. Enhanced MR images of Schmorl's nodes revealed vascularity, which was not shown on unenhanced MR images.
The time-course of appearance of five carotenoids in chylomicrons and their distribution pattern were studied following ingestion of a single dose of Betatene, a natural carotenoid source composed of 0.5% lutein, 0.75% zeaxanthin, 3.6% alpha-carotene, 70.3% all-trans beta-carotene, 22.7% beta-carotene cis isomers, 2.1% unidentified carotenoids and no lycopene. Lutein, zeaxanthin, alpha-carotene and all-trans beta-carotene but not lycopene levels in chylomicrons increased after Betatene ingestion with a maximum at 9 h and a distinct decline from 9 to 12 h. However, the carotenoid pattern in the chylomicron fraction did not match the pattern in Betatene, with a 14-fold and 4-fold higher level of lutein and zeaxanthin, respectively, compared to their content in Betatene. The contribution of alpha-carotene to the carotenoid composition in chylomicrons reflected its content in Betatene, whereas the relative amount of all-trans beta-carotene was substantially lower than in Betatene. Thus, in the presence of high amounts of beta-carotene, there is a preferential uptake of the xanthophylls lutein and zeaxanthin as compared to all-trans beta-carotene from the intestinal lumen into chylomicrons.
Narrowing of the trachea due to tracheomalacia or compression can lead to life-threatening asphyxia and may require tracheotomy with intubation or endoscopic introduction of a stent. The use of a self-expanding elastic metal prosthesis in 4 patients with airway obstruction has proved a satisfactory alternative to conventional plastic prostheses, both in the acute phase and over a long period of time. After 4 weeks total epithelium cover of the stent could be demonstrated; biopsies after 3 and 4 months showed differentiation into respiratory ciliated epithelium. Patient acceptance was excellent since there was no sensation of a foreign body, retention of secretions or cough. The physical properties of the wall stent made it a suitable mechanical replacement for an unstable or narrowed trachea during the period of observation.
42 patients with known malignancy and vertebral compressions underwent MRI. Sagittal T1-weighted spin-echo images pre and post Gd-DTPA, out of phase long TR gradient-echo images (GE) and short T1 inversion recovery images (STIR) were obtained at 1.0 T. The results were confirmed by histology (6/42) or clinical data (28/42) and follow up MRI studies (8/42). In 39 of 42 cases a correct differentiation between osteoporotic and tumorous vertebral compression fractures was possible by quantification and correlation of SE and GE signal intensities. Gd-DTPA did not improve differential diagnosis, since both tumour infiltration and bone marrow oedema in acute compression fracture showed comparable enhancement. STIR-sequences were most sensitive for pathology but unspecific due to a comparable amount of water in tumour tissue and bone marrow oedema. Susceptibility-induced signal reduction in GE images and morphologic criteria proved to be most reliable for differentiation of benign and tumour-related fractures. In the rare cases of single and nearly complete vertebral compressions with complete loss of bone marrow, differentiation with MRI was not possible.
72 T-cell lymphomas were analyzed for the presence of Epstein-Barr virus DNA using Southern or dot blot hybridization. EBV DNA was found in 25 peripheral T-cell lymphomas and in none of 6 T-lymphoblastic tumors. A high prevalence of EBV was detected in AILD type, Lennert's, pleomorphic medium and large cell nodal lymphomas and in upper aerodigestive tract lymphoma biopsies. Clonotypic analysis revealed monoclonal as well as oligoclonal viral populations. The possible influence of EBV in lymphomagenesis, the impact of virus-mediated interactions in the B- and T-cell system and factors involving site of tumor development are discussed.
Fourty-three primary cerebral lymphomas (PCL) were histologically classified and examined for genome expression of Epstein Barr Virus (EBV) and human herpes virus 6 (HHV6) using dot blotting, polymerase chain reaction, and Southern blotting. Only 20 tumors (16 high grade and 4 low grade lymphomas) could be suitably placed into a category of the Updated Kiel Classification, whereas the non-classified 23 tumors were highly malignant B-lymphomas and referred to as small-cell (SC) or large-cell (LC) blastic PCL. Most of the LC PCL showed a tumor-like infiltration pattern with high cellular density and little remaining parenchyma, whereas the SC PCL more often showed an inflammation-like pattern characterized by loose arrangement of tumor cells and marked astrocytic, microglial and T-lymphocytic reaction. EBV genome was found in 3/3 AIDS cases, but in none of 40 immunocompetent cases, while HHV6 was detected in 2 tumors of immunocompetent patients. We conclude that (1) the Updated Kiel Classification is not applicable to a majority of PCL, and (2) EBV and HHV6 do not appear to play a major role in the pathogenesis of PCL in immunocompetent subjects.
With the development of the state of medical knowledge in the special subjects and the increase of medicamentous and physiotherapeutic possibilities the indications of radiotherapy of benign nontumourous diseases changed. The application of radiotherapy altogether decreased in benign diseases. In tabular form the basic rules radiation technique of benign diseases, the indications and possibilities as well as the contraindications of the radiotherapy of benign non-tumourous diseases are described. Own experiences and evaluations confirm that the radiotherapy, for instance in acute parotitis, axillary hidradenitis, degenerative changes of the skeleton, kelloid revisions or chronic pancreatitis is an effective, rapidly acting and economic form of therapy. The knowledge about the possibilities and limits of the radiotherapy of benign non-tumourous diseases belongs to the speciality of internal medicine.
Male Wistar-H-rats were exposed monthly to a 60cobalt-source low dose whole body irradiation (0.25 Gy, total dose: 4.5 Gy). The glutathione disulphide:total glutathione ratio, the concentration of thiobarbituric acid-reactive substances and the activities of glutathione peroxidase and glutathione transferase in eight different organs and blood were analysed. The low dose irradiation is accompanied by distinct peroxidative changes in organs. These oxidative loadings occur in the small intestine, the spleen and the kidneys. The measurements of glutathione status and of thiobarbituric acid-reactive substances are proposed as sensitive parameters for low dose radiation induced changes.
The successes of modern medicine are results of the specialisation in medicine due to the technical development. With increasing specialisation several problems for education and training, for research and medical care develop, so, for instance, a total investigation of patients is not always given on a sufficient scale. Therefore it should increasedly be orientated to an education and training to a generalist both in the training of students of the subject human medicine and during the time of specialisation in the field of internal medicine. At the same time it appears necessary to discuss more intensely the integration and/or the specialisation with the internal specialists working in practice and in research, in order to develop at first a corresponding sense for the problems and to integrate the professional status of the generalist increasedly into the self-appreciation of all specialists of internal medicine.
The parvicellular carcinomas have their matrix in the neurosecretory (enterochromaffin) cells of Kultschitzky's type of the APUD-system. While in about 20% of the patients with a bronchial carcinoma a parvicellular bronchial carcinoma appears, extrapulmonary parvicellular organ carcinomas are very rarely observed. Up to 1984 altogether 72 patients with a parvicellular carcinoma of the oesophagus were world-wide registered. It is reported on an own observation of a female patient with a parvicellular carcinoma of the oesophagus and it is referred to the appearance of extrapulmonary parvicellular carcinomas. According to the present state of knowledge the extrapulmonary parvicellular carcinomas should be treated according to the therapy concepts of parvicellular bronchial carcinomas.
To informations from literature 700 patients with a hemangiopericytoma can be expected globally until the year 1988. Actually there is no uniform therapeutic procedure for this cancer disease. The own therapeutic strategy is represented, successfully applied to three patients: Actually we consider optimal the combination of surgical extirpation with following radiotherapy of the former tumor bed with a minimum target dose of 45 Gy to guarantee a total remission and a long-time survival.