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Biomedical subjects

M Teschner

Publications and source records attributed to M Teschner.

At least 37 records · Page 2Linked to original sources
PubMed2000

[Computer-assisted planning of corrective osteotomies in cases of epiphysiolysis capitis femoris].

Slipped capital femoral epiphysis (SCFE) leads to an unphysiologic function in adolescent hips. Evaluation of the slippage as well planning of corrective osteotomies is a major three-dimensional (3D) problem. Therefore, the current clinical evaluation, which is based on biplanar plain radiographs, cannot be satisfying. More is needed than simply measuring the femoral geometry to evaluate the impact of a slippage onto the physiologic hip function. We have developed a computer-based system for planning and evaluation of reorienting osteotomies in severe cases of SCFE. In our system, CT-based 3D computer models of the hip are used to simulate the range of motion within physiologic cartilage-to-cartilage contact. This helps to visualize and quantify the early impingement due to the slippage. In addition, 3D techniques allow to simulate and plan the corrective osteotomy in an intuitive way on the computer screen. Using the same range of motion system mentioned above, the projected result can be evaluated quantitatively and compared to other approaches. The motion simulation is based on the surface geometry of the joint partners rather than on a predefined, fixed rotation center. The presented system allows a much more intuitive and appropriate system for indicating and planning corrective osteotomies than conventional methods.

Adolescent↗
PubMed2000

[Possibilities of computer graphics simulation in orthopedic surgery].

BACKGROUND: In addition to standard X-rays, photographic documentation, cephalometric and model analysis, a computer-aided, three-dimensional (3D) simulation system has been developed in close cooperation with the Institute of Communications of the Friedrich-Alexander-Universität Erlangen-Nürnberg. With this simulation system a photorealistic prediction of the expected soft tissue changes can be made. Prerequisites are a 3D reconstruction of the facial skeleton and a 3D laser scan of the face. After data reduction, the two data sets can be matched. Cutting planes enable the transposition of bony segments. The laser scan of the facial surface is combined with the underlying bone via a five-layered soft tissue model to convert bone movements on the soft tissue cover realistically. CONCLUSION: Further research is necessary to replace the virtual subcutaneous soft tissue model by correct, topographic tissue anatomy.

Cephalometry↗
PubMed1999

Impingement simulation of the hip in SCFE using 3D models.

OBJECTIVE: Affecting as it does the geometry of adolescent hips, slipped capital femoral epiphysis (SCFE) and its evaluation represent a major three-dimensional problem. The current methods of clinical assessment-geometric measurements of the femur on plain radiographs or on axial computed tomographic (CT) cross-sections-address only one of the two joint components. MATERIALS AND METHODS: We have developed a system to simulate motion of hip joints with physiologic joint contact. In our system, CT-based computer models of the femur, pelvis, etc., are fitted with oriented bounding boxes (OBBs) and manipulated. Collision detection algorithms control the hip motion, which, in this virtual joint, is based on the surface geometry of the joint partners rather than on a predefined fixed rotation center. RESULTS: An illustrative case is presented to show the advantages of the new biomechanical evaluation method over conventional radiological assessments for SCFE. The proposed system provides remarkably high speed, and the necessary data can be prepared in a reasonable time. CONCLUSION: The range-of-motion assessment provides the surgeon with information about the site and the impact of nonphysiologic contact in the hip joint. The information thus obtained can be valuable for indication and planning of corrective surgery in cases of SCFE.

Adolescent↗
PubMed1999

[Effect of diclofenac on human osteoblasts and their stromal precursors in vitro in relation to arthroplasty].

INTRODUCTION: Results of animal experiments have demonstrated that the osseous integration of non-cemented prostheses can, at the very least temporarily, be impaired by the application of non-steroidal antiphlogistic agents (such as diclofenac). It is the objective of this study to examine whether there is a direct influence of diclofenac used in usual clinical dosages (3 times 50 mg daily) on bone cells and their progenitor cells which would explain the observed slow integration of the prostheses. METHODS: To investigate this, cultivated human in vitro osteoblasts and stromal bone marrow cells were incubated with increasing doses of the medications. Our study focused on the effect of diclofenac application on proliferation and functional metabolism in both cell lines. The measurable maximal plasma concentration 2 h after the application of one tablet Voltaren 50 reached 1.6 micrograms/ml. This correlated with diclofenac concentrations between 1 and 10 ml found in our experiments. The detected values were correlated to the control group (0 microgram/ml diclofenac). RESULTS: The drug effect upon osteoblasts was higher than on progenitor cells. The proliferation of in vitro stromal bone marrow cells, compared to untreated cells, was found to be decreased. We observed a decrease to 82% at a diclofenac concentration of 1 microgram/ml, Osteoblasts exhibited a decrease to 97.5% at the same concentration. The DNA synthesis increased to 118% in stromal bone marrow cells, in osteoblasts to 144%. In contrast, we detected a neglectible decrease to 92% in the collagen synthesis of osteoblasts compared to untreated cells. The synthesis of osteocalcin by osteoblasts increased to 119%. The alkaline phosphatase activity was found to be decreased to 88% in stromal bone marrow cells and increased in osteoblasts to 111%. CONCLUSION: Temporary inhibiting effects on osseous integration in non-cemented prosthesis by diclofenac could be caused by a disturbance in the anabolic bone metabolism, exhibited by an increase of osteoblastic osteocalcin expression. Osteocalcin as a known negative regulator of the osteoneogenesis is most likely inhibiting the collagen matrix deposition.

Aged↗
PubMed1999

[Influence of osteoarthrosis, osteoporosis, and rheumatoid arthritis at precision of osteodensitometry of lumbar spine and proximal femur].

UNLABELLED: Precision of osteodensitometric measurements using dual energy X-ray absorptiometry (DEXA) depends on various known factors, such as positioning, aortic calcification or vertebral fractures. The purpose of this study was to investigate the influence of various diseases or bone density on the reproducibility of measurements in the lumbar spine and the proximal femur. Measurements in the LWS p.a. , LWS lat. and at Ward's triangle were made in a total of 100 patients. The subjects were repositioned between measurements. In order to be able to determine the influence of various diseases, four groups of 25 patients each were formed: three with the diagnosis osteoarthrosis, osteoporosis and rheumatoid arthritis and one control group. The mean percentual difference and coefficient of variation were calculated as the measure for reproducibility. Mean percentual differences of 0.18 to 2.6% were found in the four groups at the three measurements sites. After calculation of coefficient of variation, a value between 1.2 and 2.7% was found for LWS p.a., between 7.1 and 15.7% for LWS lat. and between 4.1 and 9.9% at Ward's triangle. It was also conspicuous that the difference in coefficient of variation in osteoporosis patients was nearly double that in the control group in all measured areas. CONCLUSION: Lateral lumbar spinal measurements using DEXA cannot presently be recommended. LWS p.a. measurements and, with limitations, measurements at Ward's triangle have good precision and could be used for course documentation of bone density.

Absorptiometry, Photon↗
PubMed1999

Efficiency of 1-year treatment with fluvastatin in hyperlipidemic patients with nephrotic syndrome.

The influence of fluvastatin, a liver-selective, competitive inhibitor of the 3-hydroxymethyl-glutaryl-coenzyme A reductase, on the lipoprotein metabolism was investigated in 9 patients with nephrotic syndrome. All patients had biopsy-proven renal disease as cause of their nephrotic syndrome and exhibited severe hyperlipidemia [baseline: serum cholesterol 358 +/- 46 mg/dl (9.3 mmol/l), low-density lipoprotein cholesterol 236 +/- 18 mg/dl (6.1 mmol/l), triglycerides 333 +/- 28 mg/dl (3.8 mmol/l), and lipoprotein Lp(a) 46 +/- 11 mg/dl]. After 1 year of 40 mg of fluvastatin, significant reductions of total cholesterol by 31% to 242 +/- 26 mg/dl (6.3 mmol/l) and low-density lipoprotein cholesterol by 29% to 162 +/- 12 mg/dl (4.2 mmol/l) were observed. Furthermore, triglyceride values were also lowered significantly by 19% to 268 +/- 21 mg/dl (3.1 mmol/l). Lipoprotein Lp(a) and high-density lipoprotein-cholesterol remained unchanged by fluvastatin. These improvements in lipid profile were maintained during the entire follow-up period of 1 year. There were no adverse events, and the slight increase in serum creatinine observed during the study was considered to be due to the primary renal disease. In conclusion, long- term administration of fluvastatin in patients with nephrotic syndrome appears to be an effective and safe treatment of the hyperlipidemia associated with this disorder.

Adult↗
PubMed1999

Suppressed activities of cathepsins and metalloproteinases in the chronic model of puromycin aminonucleoside nephrosis.

Glomerulosclerosis and tubulointerstitial fibrosis are the hallmarks of chronic renal diseases. In the present study, we have investigated the potential involvement of various proteinases in these alterations in the model of puromycin aminonucleoside (PAN) nephrosis. Two groups of male Wistar rats were given either three or seven injections of PAN (2.0 mg/100 g body weight) over a 4- and 12-week period, respectively. The two control groups received saline injections. Activities of cathepsins (B, H and L) were determined in isolated glomeruli and proximal tubules. Moreover, collagenase-like and gelatinase-like activities were analyzed in isolated glomeruli. Three weeks after weekly PAN injection, the rats developed heavy proteinuria (140.8+/-22.0 vs. 13.5+/-3.29 mg/day; p<0.001), and at week 11 protein excretion reached 606.6+/-23.00 vs. 22.8+/-1.5 mg/day. Renal morphology revealed minimal glomerular mesangial changes at the 4th week after PAN administration. At the 12th week a marked mesangial matrix accumulation as well as severe tubulointerstitial infiltration and fibrosis associated with tubular dilation and atrophy were observed. Glomerular cathepsins B, H, and L and gelatinase-like activities decreased at the 4th week after the first PAN injection and remained at this low level throughout the entire study period. Glomerular collagenase-like activity decreased at the 4th week (p<0.05) and was still mildly lower than that of the control group at the 12th week, but without significance. In the isolated proximal tubules, the activities of cathepsins B, H, and L showed the same pattern of decreases as those found in the glomeruli over the whole experimental period. Taken together, our data in the model of chronic PAN nephrosis suggest that the suppressed activities of cathepsins as well as the decreased gelatinase- and collagenase-like activities participate in the accumulation of extracellular matrix and thereby may contribute to the development of glomerulosclerosis and tubulointerstitial fibrosis.

Animals↗
PubMed1998

[Current indications for resection of tuberculoid lung changes--relics of the pre-chemotherapy era?].

The spectrum of indications for elective resection of pulmonary tuberculosis was considerably reduced by clinical evaluation of the effective antituberculous chemotherapy and is limited only to a few pathomorphological processes and clinical situations today. The same estimation is valid in case of nontuberculous mycobacteriosis with clinical importance. The combined therapy with new macrolid antibiotics, quinoloses and Rifampicin-derivatives current enlarged the options of conservative therapy. Thus the surgery of pulmonary tuberculosis are rare operations and are essentially limited to the therapy of late complications of a former collapse therapy, of destroyed lungs and bronchiectasis with recurrent infect exacerbations and life threatening or massive recurrent haemoptysis.

Anti-Bacterial Agents↗
PubMed1998

[Surgery of late complications of previous active treatment of lung tuberculosis with extrapleural plombage].

Between January 1984 and February 1997 10 patients with late complications of a former active collapse therapy were operated. In case of our patients between 1943 and 1960 the collaps therapy was carried out with the extrapleural instillation of plombs for therapy of pulmonary tuberculosis. At present main complications were infections of plombs with pleurobronchial and pleurocutaneus fistulas and perforation of plombs. By all patients both extirpation and pleurectomy were necessary. In case of 5 patients additionally lung resection was required, in case of 3 patients a thoracoplasty and by 1 patient a myoplasty. Although there are considerable destructions of lung parenchym in a part the results of long-term follow up are satisfactory: 6 patients are so far without complaints; only 1 patient died 10 years postoperative. Prerequisite for a successful therapy are the knowledge of the surgical methods of the collaps area, the used materials, the pathomorphological pulmonary changes and the good cooperation between pneumologists and thoracic surgeons.

Adult↗
PubMed1998

Alcohol abuse: potential role in electrolyte disturbances and kidney diseases.

The present review summarizes the current knowledge on the multiple effects of alcohol overconsumption on the kidney function as well as on water, electrolyte and acid-base homeostasis. In contrast to the well known transitory diuretic effects, the overall long-term effect of chronic alcohol overconsumption is water and salt retention with expansion of extracellular volume. Furthermore, depletion of magnesium, phosphate and calcium is also frequently found in alcohol-dependent patients. These electrolyte disturbances may be associated with the alcohol-induced hypoparathyroidism and parathyroid hormone resistance of the skeletal muscle as well as with the decrease of serum osteocalcin. Metabolic acidosis with lower arterial blood pH and plasma bicarbonate concentrations was revealed in alcoholic patients upon admission and a significant correlation between chronic alcohol overconsumption and increased incidence of hyperuricemia and gout attacks was also reported. Alcohol seems to have dual effects on the blood pressure. Increased blood pressure was demonstrated in men above 80 g and in women above 40 g ethanol consumption daily. In contrast, young adults consuming only 10 to 20 g per day had lower blood pressure than the abstinent group indicating a J-curve relationship. This is in line with the lowered risk for coronary heart disease associated with regular consumption of small alcohol amounts. The mechanisms responsible for the association between alcohol overconsumption and postinfectious glomerulonephritis have not been elucidated yet. Finally severe alcohol abuse predisposes to acute renal failure and seems to be associated with the general catabolic effects.

Acute Kidney Injury↗
PubMed1998

[Endobronchial chondroma--bronchoscopic resection or thoracic surgery intervention?].

Endobronchial chondromas as a rare form of benign tumors of the bronchial tree lead not only to diagnostic problems because of the unspecific often latent pattern of symptoms, but also to therapeutic difficulties because of the macroscopic findings and the poststenotic changes of the bronchial tree and the lung parenchyma. In case of a 75-year old female patient the various therapeutic possibilities are discussed. The therapy must be individual and consider the extent of simultaneous lung changes and the general criteria of operability in thoracic surgery.

Aged↗
PubMed1996

[Malignant tracheal tumors--surgical experiences in 6 patients with primary malignancies of the trachea. Current diagnosis and therapy].

In a retrospective study six patients with malignant tumours of the trachea located distal to the cricoid and proximal to the carina tracheae were operated on during the period of December 1983 to July 1995 in the Department of Thoracic Surgery in Hannover (Heidehaus). Histopathological examination revealed two adenoid cystic carcinomas, two squamous cell carcinomas, one mucoepidermoid carcinoma, and one low-grade sarcoma. Laser bronchoscopic resection was performed in one patient and tracheotomy one other avoid imminent asphyxia. Physical examination mainly showed a range of symptoms such as stridor and dyspnoea; spirography showed increased airway resistance, and X-ray of the trachea was important in the diagnostic process. The tracheal tumours were diagnosed by histopathological examination of excised material obtained by bronchoscopy. Three patients underwent resection and primary reconstruction of the trachea, with a length of resection between 2.0 and 3.5 cm and end-to-end anastomosis. Endotracheal afterloading was necessary in the case of one female patient with tumour infiltration of the proximal end of the upper trachea. Neoadjuvant irradiation was followed by resection of the whole trachea and implantation of a tracheal prosthesis (Neville) in the case of a patient with extensive endo- and extraluminal tumour infiltration. An extensive recurrence led to the death of this patient 5 months after the surgical intervention. Because of the distal location, resection of the tracheal bifurcation was necessary in two patients, in one combined with a pneumonectomy on the right side. Stenosis of the main bronchus and development of granuloma made stent implantation unavoidable. Dislocation of the stents and recurrent pneumonia caused the patients deaths 74 days and 18 months postoperatively. On follow up 17, 93, and 120 months postoperatively none of the other patients had recurrences. Current diagnostic and therapeutic options for malignant tracheal tumours are discussed.

Adult↗
PubMed1996

Role of lysosomal cathepsin activities in cell hypertrophy induced by NH4Cl in cultured renal proximal tubule cells.

An increase of renal ammoniagenesis has been implicated in renal hypertrophy associated with various clinical disorders such as metabolic acidosis, diabetic nephropathy, and renal insufficiency. In vivo and in vitro studies have shown that ammonia promotes hypertrophy in tubular epithelial cells. To elucidate its role on protein turnover, the effects of NH4Cl on the activities of cathepsins B, H, and L+B, as well as on protein synthesis and degradation in LLC-PK1 cells, were investigated. The results show that NH4Cl (20 mM) induced cell hypertrophy, as defined by an increase in both cell protein content and cell volume (+25.5 +/- 1.3 and +10.4 +/- 0.1% after 48 h). This hypertrophy was associated with the suppression of the activities of cathepsins B and L+B (-57.0 +/- 0.9 and -54.5 +/- 1.5% after 48 h) and a reduction of protein degradation rate (-59.7 +/- 4.1% after 48 h), but without enhanced protein synthesis. The findings were further supported with an additional experiment, showing that the protein synthesis inhibitor cycloheximide (10 microM) did not blunt NH4Cl-induced cell hypertrophy. Moreover, NH4Cl (20 mM) resulted in a persistent elevation of the lysosomal pH, whereas the rise in the cytosolic pH was only transient. This alkalinization in lysosomes may be causatively involved in the impairment of the activities of cathepsins B and L+B. In conclusion, the suppression of the activities of cathepsins B and L+B and the subsequent reduction of protein breakdown due to intralysosomal alkalinization contribute to NH4Cl-induced hypertrophy in LLC-PK1 cells.

Ammonium Chloride↗
PubMed1996

Protein restriction influences glomerular matrix turnover and tubular hypertrophy by modulation of renal proteinase activities.

Following renal ablation, there is marked compensatory renal growth, which is associated with alterations in the activities of renal proteinases. In the present study, rats underwent 5/6 nephrectomy (5/6-NX). Sixteen weeks after surgery, glomeruli and tubules were isolated and proteinase activities were determined using fluorogenic peptidyl substrates. Following 5/6-NX, there was considerable compensatory renal growth resulting in a final weight of 1,923 +/- 46 mg for the remnant kidney as compared to 1,402 +/- 63 mg for the left kidney of SHAM animals. This hypertrophic response was associated with lower activities of tubular cysteine proteinases (cathepsin L & B: -43%; cathepsin B: -61%; cathepsin H: -53%). Significantly reduced activities were also observed for glomerular collagenase (20.2 +/- 6.2 vs. 53.4 +/- 5.7 mU/micrograms DNA) and gelatinase (24.1 +/- 5.0 vs. 130.8 +/- 8.4 mU/micrograms DNA) activities. Protein restriction (5 vs. 20% casein) considerably attenuated compensatory renal growth after surgical ablation (790 +/- 45 vs. 1,923 +/- 46 mg) and partially prevented the fall in tubular cathepsin activities. In terms of glomerular enzymes, protein restriction caused a significant increase in the activity of gelatinase from 24.1 +/- 5.0 to 66.7 +/- 9.2 mU/micrograms DNA, while collagenase remained unchanged. From these data, we conclude that compensatory renal growth is strongly influenced by the amount of protein ingested. It appears that this effect is mediated by modulation of renal proteinase activities.

Animals↗
PubMed1996

Influence of nitric oxide on renal function in toxic acute renal failure in the rat.

Besides other mechanisms, nitric oxide (NO) plays a major role in maintaining the high renal blood flow (RBF) and is also involved in the regulation of glomerular hemodynamics and contractility of mesangial cells. We examined the hypothesis that L-arginine-derived NO exerts beneficial effects in toxic acute renal failure (ARF) in the rat. To induce ARF uranyl nitrate (UN) was given intravenously as a bolus injection (25 mg/kg over 5 min) following a basal period. After the initiation phase of ARF (3 h) saline in the control group (C) and drugs in the experimental groups (I-III, each n = 8) were administered for 60 min. Group I: Arg (= L-arginine, 300 mg/kg), group II: MeArg (= N-methyl-L-arginine, 30 mg/kg), group III: Arg + MeArg (300 mg/kg, 30 mg/kg respectively). The experiments were continued for additional 60 min following the infusion period. Glomerular filtration rate (GFR, inulin clearance) was reduced 3 h after UN to about 50% of normal values in group I-III and control group. After infusion of Arg GFR had significantly improved, but remained unchanged after MeArg in relation to control. One hour after the infusion period these effects were even more pronounced. We conclude that NO exerts beneficial effects on renal function in this animal model of ARF. These results underline the regulatory role of the L-arginine/NO pathway for renal function not only under basal conditions but also in ARF.

Acute Kidney Injury↗