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Biomedical subjects

T Vogl

Publications and source records attributed to T Vogl.

At least 199 records · Page 11Linked to original sources
PubMed1981

[Mineral content of the peripheral skeleton in patients with diabetes mellitus ].

In order to determine the effect of diabetes mellitus on bone mineral content, measurements with the iodine 125 isotope method of Cameron were carried out in the distal ulna and calcaneus of 40 patients. 38% of female and 20% of male diabetic patients showed abnormally low values. The most severe changes were found in patients with complications of diabetes. There was a correlation between the duration of the diabetes and the severity of the mineral loss.

Adult↗
PubMedDate not supplied

Blood coagulation factors in the elderly.

To investigate causes of the age-dependent increase of thromboembolic events, plasma coagulation parameters were determined in healthy elderly blood donors in comparison with young, and elderly diseased blood donors. Partial thromboplastin and thrombin clotting times were slightly shortened, whereas prothrombin and reptilase clotting times were unaltered. Plasma concentration of clotting factors like F I, VII, VIII: C, X, HMW-kininogen and prekallikrein were increased, whereas the coagulation inhibitor antithrombin III was decreased. Concerning fibrinolysis, plasminogen and alpha-2-antiplasmin were not affected by age, but plasminogen activators in the euglobulin fraction were lower. This shift in the pattern of coagulation factors favors enhanced fibrin formation and delayed fibrinolysis in the elderly. Higher intermediary products demonstrate that activation of coagulation and fibrinolysis happen more often in elderly healthy people. Together with blood stasis and vessel wall damage, this shift of the hemostatic balance contributes to a higher incidence of thromboembolic disorders in the aged.

Aging↗
PubMedDate not supplied

Three-dimensional magnetic resonance imaging in skull base lesions.

Three-dimensional (3D) magnetic resonance (MR) imaging is a new digital technique developed 2 years ago by a multidisciplinary group of head and neck surgeons, clinical radiologists, and mathematicians at the University of Munich. In this study, the clinical value of this method, which has been improved significantly during the last 9 months, is evaluated in lesions of the skull base. Our results indicate that 3D reconstruction based on two-dimensional (2D) MR images reveals topographic details of interesting structures. In addition, this method offers new possibilities for the preoperative planning of tumor resection, particularly in lesions close to the skull base. However, this imaging technique will have to be improved before it achieves widespread clinical use.

Carcinoma, Squamous Cell↗
PubMedDate not supplied

31P-spectroscopy of head and neck tumors--surface coil technique.

Comparative phosphorus-31 magnetic resonance spectroscopy (MRS) and magnetic resonance imaging (MRI) of 15 patients with superficial masses such as sarcoma, carcinoma, lymphoma, adenoma, and tuberculosis revealed significant increased concentrations of phosphomonoester, phosphodiester, and inorganic phosphorus in the lesion, whereas the concentration of the phosphocreatine was lower in comparison to muscle tissue. In nearly all masses, pH showed a slight alkaline shift. Existence of necrotic regions detected by MRI was marked by an increase of inorganic phosphorous in the spectra. Tumor growth was characterized by raised concentrations of phosphomonoester. Follow-up studies in a case of lymphoma showed a six-fold decrease of the tumor, while the spectra indicated a gradual transition of tumor values to muscle values. A follow-up study during irradiation of a squamous cell carcinoma revealed a considerable decrease of inorganic phosphate and a subsequent increase of phosphodiester.

Adult↗
PubMedDate not supplied

[MR-based 3D-analysis of the pathomechanics of traumatic and atraumatic shoulder instability].

AIM: Until now it is unknown to what extent malpositioning of the scapula is a relevant factor in shoulder instability that should be considered in therapy. The objective was to analyse 3D-scapular kinematics and humeral head (de-)centering in patients with atraumatic and/or traumatic shoulder instability and to investigate the correlation between the two factors. METHOD: The shoulders of 28 healthy volunteers and of 14 patients each with atraumatic or traumatic instability were examined in various arm positions - with and without muscle activity - using open MR imaging. After 3D reconstruction, analyses of scapular kinematics and glenohumeral translation were performed. RESULTS: In atraumatic unstable shoulders, the scapular position [30 degrees of abduction: scapulo-humeral rhythm: 3.5 +/- 2.6 : 1 vs. healthy 2.4 +/- 1.3 : 1; internal rotation: 59 +/- 9 degrees vs. healthy 49 +/- 3 degrees (p < 0.05)] and humeral head position was significantly decentered in both planes (p < 0.05). While the correlation between the two factors was high during passive elevation (r = 0.60-0.87), it was low during muscular activity (r = 0.25-0.62). In patients with traumatic instability no alterations of the scapula kinematics were observed. Significant humeral head decentering (p < 0.05) occurred only during abduction and external rotation. CONCLUSIONS: Patients with atraumatic instability demonstrated significant alterations of scapular kinematics and decentering of the humeral head. In traumatic instability a decentering occurred only in specific arm positions with no changes in scapula position. Because of the high correlation between the two factors, physiotherapeutic strategies for the scapula-stabilising muscles should be adapted to the direction of instability.

Adolescent↗
PubMedDate not supplied

[Magnetic resonance tomography studies of the hypophysis in children with growth hormone deficiency, born with umbilical cord entanglement].

Eight children with either panhypopituarism, severe growth hormone deficiency or neurosecretory dysfunction for growth hormone with a common history of umbilical cord encirclement around the neck underwent magnetic resonance imaging of the pituitary gland and the hypothalamus. Panhypopituitarism was associated with small to absent adenohypophysis, narrow or absent stalk and ectopic neurohypophysis whereas patients with partial GHD showed normal anatomical structures. Etiology of the endocrinopathy could be a primary malformation of the pituitary gland, an apoplexy of the gland or disturbation within the hypothalamus. We believe that the latter cause is predominant in umbilical cord encirclement.

Adolescent↗
PubMedDate not supplied

MR imaging of the oropharynx and tongue: comparison of plain and Gd-DTPA studies.

The effect of intravenously administered gadolinium-diethylene-triamine pentaacetic acid (Gd-DTPA) on signal intensity in comparison to plain noncontrast imaging was analyzed. Sixty-one patients with diseases of the oropharynx and tongue base were examined using multiplanar magnetic resonance (MR) imaging. The contrast medium Gd-DTPA was administered in 26 cases. Thirty-eight patients also underwent CT. Forty-one patients had surgery and pathological verification. Plain MR imaging was equal or superior to CT in all except one patient. Marked contrast enhancement produced by Gd-DTPA was observed in carcinomas, sarcomas, inflamed salivary glands, and in normal pharyngeal mucosa. The usefulness of Gd-DTPA may be increased by measuring the enhancement in signal intensity versus time to allow a better differentiation of histological features.

Gadolinium↗
PubMedDate not supplied

MR imaging in pediatric airway obstruction.

Magnetic resonance (MR) imaging of the trachea was performed in 27 children with congenital tracheal narrowing. The diagnoses included aortic arch anomalies (n = 7), innominate artery compression (n = 13), pulmonary artery compression (n = 5), and tracheomalacia (n = 2). Demonstration of the trachea and the surrounding tissue and vessels on MR images allowed the evaluation of the cause of tracheal compression and the degree and location of collapse. Patients were examined with MR imaging if the cause of airway obstruction was still unclear after bronchoscopy. It is concluded that MR imaging is a well suited modality for characterizing tracheal narrowing without using ionizing radiation or intravenous contrast medium.

Airway Obstruction↗
PubMedDate not supplied

Influence of magnetic resonance imaging on human body core and intravascular temperature.

Deep and superficial body temperatures were measured by in vitro and in vivo experiments, using a fluoroptic procedure and a variety of magnetic and electromagnetic fields, in the course of magnetic resonance imaging (0.35 T; 1.5 T). In vitro experiments were performed to select and check the appropriate temperature method. Temperature measurements in the human body were carried out centrally (esophageal and rectal measurements). In vivo experiments in 30 volunteers showed no significant changes (p = 0.05) in central or peripheral temperatures resulting from the application of static or dynamic fields or radiofrequency.

Blood Circulation↗
PubMedDate not supplied

Cellular uptake of magnetic fluid particles and their effects on human adenocarcinoma cells exposed to AC magnetic fields in vitro.

Suspensions of coated superparamagnetic particles (magnetic fluids, MF) in AC magnetic fields have a pronounced specific absorption rate (SAR) per mass compared to multidomain particles. The aim of the present study was to investigate cellular uptake and the biological effects of AC magnetic field excited bio-compatible magnetic fluids on human carcinoma cells in vitro. One of the fluids tested was a dextran magnetite, which has a very low cyto-toxicity with survival fractions (SF) between 0.8 and 0.9 at concentrations of up to 5 mg ferrite per ml. Human carcinoma cells intracellularly accumulate up to 1 pg ferrite/cell which has been demonstrated by electron microscopy (TEM), X-ray spectroscopy and measurements of intracellular iron. It has been shown that the ferrite core is not altered intracellularly, but many of the dextran shells are degraded which yields particle chains and other aggregates observed in TEM. Semi-solid pellets of the tumour cells were treated with AC magnetic fields (520 kHz, 4-12.5 kA/m) or waterbath hyperthermia at 43 and 45 degrees C, in presence of extracellular and/or intracellular magnetic fluid particles. Although MF heating is produced from individual particles, the survival fractions of MF heated and water bath heated cells are equal. In fact, the extracellular MF particle distribution is homogeneous enough to obtain similar inactivation. In contrast to earlier reports intracellular dextran magnetite particles in AC magnetic fields did not induce cell inactivation. Since the amount of intracellular ferrite should be indeed large enough for cell inactivation, the loss of dextran shells is most probably the main cause of limited effectiveness of the intracellular magnetite particles. The present work has demonstrated that: (1) MFH is able to inactivate tumour cells in vitro to at least the same extent as water bath hyperthermia; and (2) that there is a sensitizer effect of ferrofluids at 43 degrees C probably caused by free ferric ions which induce oxidative stress; and (3) that there is no cytotoxic effect of intracellular dextran magnetite particles 30-180 min excited with AC magnetic fields used in this study. For the new method the term 'magnetic fluid hyperthermia (MFH)' is proposed.

Adenocarcinoma↗
PubMedDate not supplied

Effects of magnetic fluid hyperthermia (MFH) on C3H mammary carcinoma in vivo.

Magnetic fluids (MF) have a potential for hyperthermia due to their good power absorption capabilities. Recent in vitro experiments with the so-called 'Magnetic Fluid Hyperthermia (MFH)' have shown that human tumours cells are homogeneously inactivated after AC magnetic field excitation of extracellular MF. The aim of the present study was the evaluation of a high dose MFH on intramuscularly implanted mammary carcinoma of the mouse. The tumours originated from initial in vivo passages of a spontaneous parent tumour. Because of larger variations of tumour growth in this rather primary model, logistic regression of non-averaged volumes was performed for each treatment modality. All growing tumours were randomized 30 days after transplantation (day of treatment) with an overall size distribution between 120-400 mm3. An intratumoural steady state temperature of 47 +/- 1.0 degrees C was maintained for 30 minutes with whole-body AC magnetic fields of 6-12.5 kA/m at 520 kHz. The magnetic fluid was #P6, which is a high biocompatible dextran magnetite. #P6 was given intratumourally (1.5 x 10(-2) mg ferrite/mm3) 20-30 minutes before excitation and was combined with magnetic targeting (50 mT), which yielded a 2.5-fold enhancement of the intratumoural iron concentration. Histological examinations of tumour tissue after intralesional ferrofluid administration alone indicated deep infiltration of the fluid into the carcinoma tissue, but no evidence of tissue damage as compared with untreated controls. In contrast, widespread tumour necrosis was observed after MFH. After application of either dextran or ferrofluid alone (no difference, p = 0.665), tumour growth was slightly delayed in comparison with untreated controls (p < 0.001). In contrast to the good fit of the controls (R = 0.92-0.87), tumour growth after MFH was much more heterogeneous; some tumours showed no evidence for regrowth at 50 days whereas others had grown quite readily. This most probably reflected the critical problem of homogeneity of the intratumoural MF distribution, which was also confirmed qualitatively by Magnetic Resonance Imaging (MRI), heterogeneous pigmentation of MFH treated tumours, and up to 1 degree C differences between temperature probes in the same tumour during AC magnetic field application. However, a quantitative comparison between intratumoural MF-heterogeneity and tumour response could not be performed in this study. Despite these current limitations, the regression analysis of the MFH data yielded a smaller tumour volume of about 1000 mm3 at 50 days growth time in contrast to all three controls. In conclusion, encouraging results have been obtained, which show, that one single high dose MFH is already able to induce local tumour control in many cases within 30 days after treatment. To overcome the uncertainties of intratumoural MF heterogeneity, advanced intralesional application methods are currently under development.

Animals↗
PubMedDate not supplied

Heat response of HT29 cells depends strongly on perfusion--a 31P NMR spectroscopy, HPLC and cell survival analysis.

A model system of perfused human colon adenocarcinoma cells (HT29) encapsulated in alginate was used to examine metabolic response to heat therapy with 31P NMR spectroscopy, HPLC and cell survival analysis. The presented data show, that perfused (medium flow during hyperthermia) and non-perfused (no medium flow during hyperthermia) cells are very difficult in their sensitivity to hyperthermia. Under equivalent experimental conditions with respect to medium pH, oxygen and nutrient concentration, encapsulated perfused HT 29 cells display a significantly lower thermal sensitivity than non-perfused cells. This reduced sensitivity of perfused cells is characterized by an increased cell survival and relative ATP concentration, and reduced drop of the NTP/Pi ratio in the long-term follow up towards zero. The relative ATP concentration determined by HPLC after hyperthermia is correlated with the clonogenic survival fraction. There is a direct relationship, depending on the specific experimental conditions (perfused, non-perfused). For perfused cells only a slight dependency of survival and relative ATP concentration on heat dose is observed. In consequence, the correlation between survival and relative ATP concentration is weak, described by log(SFperf) = 0.7*[ATP-12.4, R2 = 0.79, p < 0.04. For non-perfused cells the correlation is stronger resulting in a relationship of log(SFno perf) = 0.6*[ATP]-9.0, R2 = 0.98, p < 0.0002. Altogether, the presented data suggest that the relative ATP concentration measured by HPLC after hyperthermia might be predictive for cell survival. On the other hand, a dependence between cell survival and long-term changes of NTP/Pi has been found. The results confirm the importance of tumour perfusion for hyperthermia-induced metabolic changes and cytotoxicity and therefore, for the therapeutic outcome.

Adenosine Triphosphate↗
PubMedDate not supplied

Myeloid related proteins MRP8/MRP14 may predict disease flares in juvenile idiopathic arthritis.

OBJECTIVE: An unsolved problem in juvenile idiopathic arthritis (JIA) is to identify patients at special risk for relapse. It is important to adjust anti-inflammatory and immunosuppressive therapy to the children's actual disease activity especially in times of remission. Our aim was to analyze if the serum levels of MRP8/MRP14 are reliable predictive markers for the risk of relapse in clinically inactive juvenile idiopathic arthritis. METHODS: Serum concentrations of MRP8/MRP14 were determined by ELISA and correlated with laboratory and clinical parameters for disease activity in patients with JIA. 29 patients with changing disease activity were followed up for a mean time of 2.9 years. Two groups of patients--one before relapse (mean 3.7 months) but without clinical signs of disease reactivation, and one in remission for 12 further months--were compared. RESULTS: MRP8/MRP14 serum levels in patients before relapses were significantly higher than the levels in patients in stable remission for one year (662 ng/ml versus 395 ng/ml; p < 0.05). Using a cut-off for MRP8/MRP14 of 450 ng/ml the likelihood ratio for relapse was 3.7 (positive predictive value 80%), while no differences were found for C-reactive protein and erythrocyte sedimentation rate between the two groups. CONCLUSION: MRP8/MRP14 correlate with individual disease activity in patients with JIA. Our data suggest that local disease activity may be present even months before flares become clinically apparent. Serum levels of MRP8/MRP14 can give a hint as to clinically occult disease activity, in this way helping to adjust therapy in times of low disease activity.

Adolescent↗
PubMedDate not supplied

Tumors of the nasopharynx and adjacent areas: MR imaging with Gd-DTPA.

The purpose of this study was to describe our experience with Gd-DTPA-enhanced MR imaging in the evaluation of the most common nasopharyngeal tumors. Forty-two patients with tumors of the nasopharynx and adjacent spaces had MR imaging before and after IV injection of Gd-DTPA. Images were obtained with a 1.0-T superconducting magnet imaging system in transverse, coronal, and sagittal planes with T1- and T2-weighted sequences. MR images were compared with CT scans and tumor histology. The studies were categorized by using a grading system with grades ranging from unsatisfactory (grade 0) to optimal (grade 3). Contrast-enhanced MR enables better identification of small anatomic details such as both palatini muscles and the pharyngobasilar fascia. MR after Gd-DTPA was superior to CT in all cases except for tumors of the maxillary sinuses. MR with Gd-DTPA is recommended for tumors that are small and difficult to detect on the initial nonenhanced MR examination or that show subtle infiltrations. Because of the increased cost and longer examination time, MR with Gd-DTPA does not need to be done when large tumors are well delineated.

Carcinoma, Squamous Cell↗
PubMedDate not supplied

[Results of magnetic resonance tomography (MRT) in 100 temporomandibular joints].

The results obtained by MRT of 100 temporomandibular joints in 12 probands with healthy dentitions and 38 patients are reported. The findings were dominated by dislocations of the articular disk. Diagnosis of this condition presented no difficulties, as the interarticular disk can be well differentiated from the adjoining bone structures and the bilaminar zone. The high quality of the soft tissue images renders MRT a valuable procedure completing other examination methods such as panoramic or Schüller radiographs for diagnosis of TMJ diseases.

Adult↗