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Biomedical subjects

J Fritz

Publications and source records attributed to J Fritz.

At least 19 recordsLinked to original sources
PubMed2006

Magnetic resonance imaging for hepatic radiofrequency ablation.

Image-guided radiofrequency (RF) ablation is a minimally invasive therapy option in the treatment of primary and secondary hepatic malignancies. Magnetic resonance (MR) imaging offers an accurate pre-interventional imaging having important impact on patient selection and planning of the ablation procedure. Peri-interventional imaging is used for targeting, monitoring, and controlling of the ablation procedure. Due to a high soft-tissue contrast offering delineation of tumor tissue and the surrounding anatomy, coupled with multiplanar capabilities, MR imaging is an advantageous targeting technique compared with ultrasonography (US) or computed tomography (CT). MR imaging is sensitive to thermal effects enabling a monitoring of ablation therapy subsequently being supportive to control the ablation procedure. Therefore, MR imaging can fulfil the conditions for overlapping ablations by enabling a precise repositioning of the MR compatible RF applicator if required. Thus, the probability of achieving complete coagulation in larger tumors within a single therapy session is potentially increased. A monitoring of thermal effects is moreover essential in order to prevent unintended tissue damage from critical structures in the surrounding of the target tissue. Post-interventional imaging is performed to assess treatment response after RF ablation and has prognostic impact, as an early detection of treatment failure, e.g. residual tumor tissue, enables immediate therapy. Nevertheless, differential diagnostic difficulties arise from benign periablational enhancement which may cover tumor tissue. Hence, further evaluation and improvement in the assessment of treatment response is essential.

Catheter Ablation↗
PubMed2006

[Cartilage repair in the knee joint].

Full thickness defects of the articular cartilage in the knee joint have lower regenerative properties compared to chondral lesions of the ankle. In order to avoid early osteoarthritis, symptomatic articular cartilage defects in younger patients should undergo biological reconstruction as early as possible. There are different surgical procedures available to achieve a biological resurfacing of the articular joint line. Numerous animal experiments and clinical studies have shown that early biological reconstruction of circumscribed cartilage defects in the knee is superior to a conservative or delayed operative treatment. This effect refers not only to the defect healing but also to the elimination of changes following secondary osteoarthritis. The different surgical procedures can be differentiated concerning the various indications and the final outcome. Additional malalignment, meniscus tears, and/or ligament instabilities should be treated simultaneously together with the cartilage resurfacing. The mid- and long-term results of the different current techniques are promising, but further modifications and improvements are needed.

Arthroplasty↗
PubMed2005

Magnetic resonance imaging guided corticosteroid injection of sacroiliac joints in patients with spondylarthropathy. Are multiple injections more beneficial?

Efficacy of a second magnetic resonance (MR) imaging guided corticosteroid injection of inflamed sacroiliac joints (SIJ) in patients with spondylarthropathy. Thirty-one patients received 50 injections in an outpatient basis. Fifteen of 31 patients who relapsed or were non-responders received a second injection. All had MR guided injection of 40 mg triamcinolone acetonide into SIJ using an open 0.2 Tesla unit. Twenty of 31 patients after the first injection, and 9 of 15 patients after the second injection reported subjective improvement, which lasted for a mean of 8.7+/-10.9 and 16.1+/-15.8 months for each group. Subchondral bone marrow edema resolved in 15 of 20 patients who reported subjective improvement, after the first injection. No complications occurred. MR guided steroid injection of SIJ is effective and safe. Since there is no exposure to radiation it could be performed many times. Repeated injections seem to be beneficial for primary non-responders and patients who relapsed.

Adolescent↗
PubMed2005

Effect of human platelet supernatant on proliferation and matrix synthesis of human articular chondrocytes in monolayer and three-dimensional alginate cultures.

Articular cartilage is rich in collagen type II fibres and proteoglycans and is characterized by low cell density. Chondrocytes have specific nutritional requirements and therefore cannot be expanded in vitro without the risk of generating fibroblastoid cells expressing type I collagen. Therefore, various growth conditions were tested for cartilage tissue engineering. Human platelets are a rich source of many growth factors including transforming growth factor-beta and platelet-derived growth factor. To investigate the effect of human platelet supernatant (hPS) on chondrocyte proliferation and differentiation, human articular biopsies obtained from three healthy donors. Chondrocytes were isolated and expanded separately in monolayer cultures and seeded in alginate beads in the presence and absence of hPS of 1% or 10% v/v concentration. Transcript levels of genes encoding chondrogenic factors were determined by quantitative reverse transcriptase-polymerase chain reaction. The deposition of types I and II collagen as well as proteoglycan was detected by indirect immunocytochemistry. Addition of hPS activated chondrocyte proliferation in monolayer cultures but induced a dedifferentiation of chondrocytes towards a fibroblast-like phenotype. The expression levels of mRNAs encoding type II collagen, aggrecan and bone morphogenetic protein-2 were reduced in all samples tested. Seeding chondrocytes in alginate beads in the presence of hPS generated a cell population capable of type II collagen expression, even though hPS induced considerable type I collagen expression as well. Differences (1% vs. 10% group, 1% vs. control, 10% vs. control) in the quantitative gene expression of types I and II collagen or of aggrecan were statistically significant (p<0.001). We conclude that addition of hPS may accelerate chondrocyte expansion but can lead to their dedifferentiation.

Adult↗
PubMed2005

[Significance and technique of autologous chondrocyte transplantation].

The bad risk for an early onset of osteoarthritis in the knee increases with the size of a cartilage defect. A collateral meniscus- or ligament-tear will enforce this hazard in addition. In order to avoid such a development, relevant full-thickness cartilage defects should be reconstructed biologically and attendant meniscus- or ligament-tears as well as varus- or valgus deformities should be treated. A number of studies, including some prospective-randomized trials, have shown that autologous chondrocyte transplantation (ACT) is the most reliable procedure for a surgical treatment of full-thickness cartilage defects larger than 4 cm (2) in adults. One disadvantage of ACT is the extensive approach to the joint and often a hypertrophy of the repair tissue. To solve these problems, some different biomaterials for a matrix-assisted ACT have been developed. The scaffold we use has a covering membrane upside and a collagen-sponge carrying the chondrocytes. By means of special surgical instruments a minimally invasive implantation is possible, reducing the side-effects of an extensive approach. Animal studies showed the regeneration of a hyaline cartilage using our described system. However, results of current clinical studies with the different scaffolds must be awaited before an universal application of matrix-assisted ACT can be recommended.

Adult↗
PubMed2005

[Magnetic resonance imaging -- guided corticosteroid-infiltration of the sacroiliac joints: pain therapy of sacroiliitis in patients with ankylosing spondylitis].

PURPOSE: To evaluate the efficacy and specific properties of MR imaging-guided corticosteroid infiltration of the sacroiliac (SI) joints in the treatment of therapy-refractory sacroiliitis in patients with ankylosing spondylitis. MATERIALS AND METHODS: In this study, 26 patients were prospectively included. Inclusion criteria were AS with therapy refractory acute sacroiliitis and inflammatory back pain > or = 6 months. The intervention was performed using an open low-field MR-scanner. Inflammatory back pain was assessed on a visual analog scale (VAS). Success of the therapy was defined as an absolute reduction of the VAS score </= 5, a relative reduction of the VAS score > or = 35 % and persisting improvement > or = 2 months. The grade of sacroiliitis was documented using high-field MR imaging. Variables were compared using McNemar test and Wilcoxon test. The mean remission time was calculated using a Kaplan-Meier analysis. A p-value < 0.05 was considered statistically significant. RESULTS: The intervention was technically successfully performed in all patients. Following MR imaging-guided corticosteroid infiltration of the SI joints, the VAS score improved from 8 (5 - 10) points to 4.5 (0 - 8) points (- 44 %) in all patients (n = 26), which was statistically significant (p < 0.001). Of 26 patients, 22 (85 %) fulfilled the predefined criteria for successful therapy. This group had a statistically significant (p < 0.01) improvement of the VAS score from 8 (6 - 10) to 3 (0 - 5) (- 63 %). Improvement was seen after 7 (1 - 30) days. There was a marked reduction of the subchondral bone marrow edema (- 38 %). The mean remission time was 12 (4 - 18) months. CONCLUSION: MR imaging-guided corticosteroid infiltration of the SI joints proved to be an effective therapy of inflammatory back pain in patients with therapy refractory AS. With the ability of multiplanar imaging, precise localization of the bone marrow edema and the lack of ionizing radiation, interventional MR imaging currently represents the superior method for the treatment of the predominantly young patient group presenting with ankylosing spondylitis. Owing to short intervention times, open MR-scanners are ideally suited for MR imaging-guided infiltration of the SI joints.

Adrenal Cortex Hormones↗
PubMed2004

[Radio-ulnar and radio-scaphoid-lunate arthrodesis in chronic polyarthritis. Clinical and radiologic follow-up of 32 cases].

INTRODUCTION: In 75% of all cases of rheumatoid arthritis the wrist is affected and in 12% is the region of initial manifestation of this chronic inflammatory joint disease. To prevent destruction of the wrist through carpal dislocation, radiolunate and radioscapholunate arthrodeses have increased in importance. METHODS: During a 6.5-year period, 28 radiolunate and 4 radioscapholunate arthrodeses were performed in 30 patients. The indication for operation was progressive carpal translation and increasing subluxation of the wrist in which existent radiological damage had not reached more than grade III according to the classification of Larsen and co-workers. RESULTS: The results obtained during the follow-up study (median: 17.3 months) showed in most treated patients after partial arthrodesis of the wrist no or fewer complaints concerning swelling and pain and an acceptable remaining range of motion of the wrist in everyday life. In patients with preoperatively existing ulnar deviation less than 15 degrees progressive carpal collapse and dislocation could be mostly prevented. CONCLUSION: All told radiolunate and radioscapholunate arthrodeses successfully stabilized the wrist in patients suffering from rheumatoid arthritis.

Adult↗
PubMed2002

Perivenous application of fibrin glue reduces early injury to the human saphenous vein graft wall in an ex vivo model.

OBJECTIVES: From animal and clinical studies it is known that prevention of 'over-distention' of vein grafts by using extravascular support ameliorates the arterialization process in vein grafts with subsequent more favorable patency. The most ideal support is a biodegradable, porous, elastic graft (Biomaterials, 15 (1994) 83). However, a specific graft meeting these criteria is not available yet. Fibrin glue on the other hand, although used for other purposes in cardiac surgery, theoretically meets the criteria for ideal extravascular support. In this ex vivo study, we evaluated the possible beneficial effect of perivenous application of fibrin glue. METHODS: Segments of human vein graft obtained during CABG procedures in 14 consecutive patients were placed in a side loop of the extracorporeal perfusion circuit. In this way the study vein grafts did meet identical circumstances as the vein grafts implanted. Perfusion in the loop was started with a flow just enough to counteract the collapse of the vein, usually about 8 mm Hg, and alternately around the segments fibrin glue was applied or no perivenous support was administered as control. After 1 min of soldification, perfusion was started with a pressure of about 60 mm Hg (non-pulsatile flow). Perfusion was maintained for 60 min, after which the grafts were collected for light microscopic and electron microscopic assessment. RESULTS: Light microscopy and electron microscopy showed remarkable attenuation of endothelial cell loss and less injury of smooth muscle cells of the circular muscle layer of the media in the fibrin glue supported vein grafts compared to the non-supported group. CONCLUSION: Fibrin glue is able to accomplish adequate external vein graft support, preventing overdistention, in an ex vivo model. This provides a basis for clinical application. Further investigation is necessary to evaluate long-term effects.

Coronary Artery Bypass↗
PubMed2002

Novel therapeutic approach: ligands for PPARgamma and retinoid receptors induce apoptosis in bcl-2-positive human breast cancer cells.

Effective treatment of tumors is often associated with activation of the endogenous apoptosis pathways. We have studied eight breast cancer cell lines (MCF-7, BT20, BT474, MDA-MB-231, MDA-MB-436, SKBR3, T-47D, ZR-75-1) possessing a variety of genetic defects. The clonogenic growth of breast cancer cell lines was inhibited by a ligand for PPARgamma (troglitazone, TGZ) combined with a ligand for either retinoid X receptor (RXR) (LG10069) (4/8 cell lines), RAR (ATRA) (5/8 cell lines) or RAR/RXR and RXR/RXR (9-cis-RA) (5/8 cell lines) independent of their expression of bcl-2, bag-1, ERalpha, and p53. The cell lines (MCF-7, T-47D, ZR-75-1), which expressed both BRCA1 and p27, were extremely sensitive to the inhibitory effect of the combination of TGZ and either ATRA or 9-cis-RA (ED90, 2-5 x 10(-11) M). However, only MCF-7, MDA-MB-231, and ZR-75-1 cells, which expressed a high level of bcl-2 protein, underwent apoptosis when exposed to the combination of TGZ and either ATRA or 9-cis-RA. Importantly, this effect was independent of expression levels of p53, ERalpha, HER-2/neu, bag-1, and BRCA1. Therefore, the combination of ligands for PPARgamma and retinoid receptors may have a therapeutic role for breast cancer.

Apoptosis↗