Biomedical subjects

H W Neumann

Publications and source records attributed to H W Neumann.

At least 37 records · Page 2Linked to original sources

PubMed1999

[Experiences with the GSB (Geschwend-Scheier-Bähler) III total endoprosthesis in the elbow joint].

Studies on the results with elbow prostheses published in the seventies reported on marked problems such as high loosening rates and instabilities of the joints. However, enormous progresses in elbow replacements have been made in the meantime. Therefore, we analyzed the results of the GSB III-elbow-prostheses that were implanted in our department for 9 years. Between January 1, 1987 and April 1995 at our department 34 total elbow replacements were performed in 32 patients. In this study, we reviewed 25 patients with elbow replacements both clinically and radiologically. The clinical outcome was rated according to the score of INGLIS and PELLICI. The mean follow-up time was 3.7 years. Our follow up examination revealed a total complication rate of 22%. Septic prosthesis loosening with explantation of the prostheses occurred in 3 patients resulting in a prosthesis survival-rate of 88%. However, clinical assessment revealed 80% excellent or good results. While the range of motion could only be improved to a small degree, a marked reduction of the preoperative pain could be achieved. Patients were satisfied with the outcome of the operation in 97%. Although the results of total elbow arthroplasties cannot be compared with those of hip or knee arthroplasties, in selected patients with rheumatoid arthritis and osteoathrosis the use of elbow replacements proved to be a successful procedure with satisfactory results. The implantation of elbow prostheses should mainly be considered when debilitating pain, strongly limited range of motion and instability of the joint are the main problems.

Arthritis, Rheumatoid↗

PubMed1999

[New findings in orthopedic pathology].

The term orthopedic pathology refers to bone- and joint-affecting diseases which are important for the orthopedic surgeon. In the report presented here, emphasis is placed on the membrane-associated proteolysis, which is essential for the degradation of the extracellular matrix. Matrix-degrading processes play a role not only in arthrosis but also in rheumatoid arthritis. Moreover, they are strongly associated with the problem of loosening of protheses, which is of utmost importance for the orthopedic surgeon. In these processes, major roles are played by the plasminogen activator system, plasmin, different matrix metalloproteinases, including the membrane type matrix metalloproteases and different cathepsins. A deeper insight into the function of these proteins and their influence on the matrix degradation in joint diseases will open the way for new diagnostic and therapeutic strategies. Investigations into a large number of chondrosarcomas have shown that for this type of bone lesions, urokinase plasminogen activator and cathepsin B are prognostic parameters that are independent of the differentiation grade. Also, in this context, investigations into the membrane-bound proteases will be of great practical and diagnostic value.

Arthroplasty, Replacement↗

PubMed1998

Genetic instability in osteoblastic tumors of the skeletal system.

At the histological level, the differential diagnosis of osteoblastic bone tumors is characterized by several problems that cannot be solved by conventional histological methods including immunohistology. Differentiating aneurysmal bone cyst from telangiectatic osteosarcoma or giant cell tumor from giant cell-containing highly malignant osteosarcoma are only two examples reflecting the complexity of this field. To develop a new approach to these diagnostic problems, we analyzed the genetic instability in a large number of bone-forming tumor-like lesions as well as in benign and malignant osteoblastic tumors. Our research concentrated on genetic alterations in cell cycle regulator genes: mutations in the p53 gene and ras gene, loss of heterozygosity at the p53, p16 and Rb-locus, and amplification of the mdm2-gene and the c-myc-gene. In addition to cell cycle regulators, the telomerase activity has also been analyzed. The results show that the number of genetic alterations increases with the malignancy of the tumors. The highest number of genetic alterations could thus be found in conventional intraosseous osteosarcoma. In tumor-like lesions, genetic alterations have rarely been observed. The results of this study show that analyzing the genetic instability probably contributes to an improvement in the differential diagnosis of osteoblastic tumors.

Bone Neoplasms↗

PubMed1998

[Genetic instability in osteoblastic tumors of the skeletal system].

In the histological differential diagnosis of osteoblastic bone tumors, several problems could not have been solved by conventional histological methods including immunohistology. Some well-known examples are the differential diagnosis between aneurysmal bone cyst and telangiectatic osteosarcoma and giant cell tumor versus giant cell-containing highly malignant osteosarcoma. As a new approach to these diagnostic problems, we analyzed the genetic instability in a larger number of bone-forming tumor-like lesions, benign and malignant osteoblastic tumors. Analysis focused on genetic alterations in cell cycle regulator genes: Mutations in the p53 gene and ras gene, loss of heterozygosity at the p53, p16 and Rb-locus, and amplification of the mdm2 gene and the c-myc-gene. In addition to cell cycle regulators, the telomerase activity has also been analyzed. The results show that the number of genetic alterations increases with the malignancy of the tumors. The highest number of genetic alterations could thus be found in conventional intraosseous osteosarcoma. In tumor-like lesions, genetic alterations have rarely been observed. The results of this study show that the analysis of genetic instability will probably contribute to an improved differential diagnosis of osteoblastic tumors.

Bone Neoplasms↗

PubMed1996

[A new score for comparing outcome of surgical management of Achilles tendon ruptures].

From January 1987 to March 1994 three hospitals in the city of Magdeburg treated a total of 103 subcutaneous Achilles tendon ruptures operatively. We created a special score to compare the outcome of the different operation techniques used. Important aspects of the follow-up examination were isokinetic measuring of power and staying power by means of a KIN-TREX dynamic measuring device and the clinical check-up in comparison with the histological results and the patients' history. Degeneration could only be proved histologically in 38,8% of the cases. The average score of all OP methods applied was 767 of possible 1000 points. The adaptation suture (781 points), Silfverskiold's technique (772 points) and the fibrin adhesive technique (754 points) showed approximately the same results. The theory that all of the ruptures have a histological degeneration background seems to be wrong. Isokinetic measuring can be very helpful in preparing a postoperative regimen to find the optimum load.

Achilles Tendon↗

PubMed1994

Caffeine and Ca2+ stimulate mitochondrial oxidative phosphorylation in saponin-skinned human skeletal muscle fibers due to activation of actomyosin ATPase.

The rate of mitochondrial oxidative phosphorylation of saponin-skinned human muscle fibers from m. vastus lateralis in the presence of glutamate, malate and ATP is reported to be sensitive to caffeine and to changes of free calcium ion concentration. An approximately twofold increase in respiration was observed by the addition of 15 mM caffeine, because of the efflux of calcium from sarcoplasmic reticulum. Direct addition of a Ca2+/CaEGTA buffer, containing 1.5 microM free calcium ions had a similar effect. The ATP-splitting activity of skinned fibers was also stimulated by caffeine or calcium. These observations can be explained exclusively by the calcium-induced activation of actomyosin ATPase. (i) Thapsigargin, an inhibitor of the sarcoplasmic reticulum Ca(2+)-ATPase, had no influence. (ii) In myosin-extracted 'ghost' fibers containing intact mitochondria and an intact sarcoplasmic reticulum caffeine had a negligible effect on oxidative phosphorylation. (iii) The caffeine-induced increase in rate of fiber respiration was concomitant with a decrease in mitochondrial membrane potential and a decrease in the redox state of the mitochondrial NAD system. (iv) The calcium ionophore A 23187 caused a stimulation of respiration and ATP-splitting activity, similar to caffeine. (v) The calcium dependencies of respiration and ATP splitting activity of saponin-skinned human muscle fibers were in experimental error identical. Therefore it is concluded that calcium efflux from sarcoplasmic reticulum affects oxidative phosphorylation in skeletal muscle mostly via the stimulation of actomyosin ATPase.

Caffeine↗

PubMed1994

Measurement of fluorescence changes of NAD(P)H and of fluorescent flavoproteins in saponin-skinned human skeletal muscle fibers.

Saponin-skinned human muscle fibers from M. vastus lateralis were immobilized in a quartz capillary to detect the fluorescence changes of NAD(P)H and of fluorescent flavoproteins. To get sufficient intense fluorescence signals from a small amount of muscle tissue the NAD(P)H fluorescence was excited by means of an HeCd laser at 325 nm and the flavoprotein fluorescence by an argon-ion laser at 454 nm or by the second wavelength of a HeCd laser at 442 nm. Using this experimental setup the fluorescence spectra of NAD(P)H, of alpha-lipoamide dehydrogenase and of electron-transfer flavoprotein were detected in saponin-skinned human muscle fibers. These fibers behaved identically to isolated mitochondria: (i) The addition of substrates caused an increase in reduction of mitochondrial NAD+, (ii) the addition of ADP caused its reoxidation, and (iii) the addition of respiratory chain inhibitors led to an almost complete reduction of NAD+. It was observed that the redox state of the NAD(P) system and of the alpha-lipoamide dehydrogenase reached after addition of 1 mM ADP correlates with the rate of active state respiration with NAD-dependent substrates. Therefore, this fluorimetric method is suitable to compare the mitochondrial oxidation capacities of NAD-dependent substrates in less then 5 mg wet weight muscle tissue. Moreover, the maximal changes in fluorescence of NAD(P)H and flavoproteins correlate with the amount of mitochondrial marker enzymes per milligram muscle tissue. Using this method a myopathy caused by a diminished content of mitochondria per milligram muscle tissue was observed.

Adenosine Diphosphate↗

PubMed1994

[Extra-articular pathogenetic factors in arthritis and deformities in old age as exemplified by varus gonarthrosis].

Extraarticular, predominantly neuromuscular, factors are thought to contribute to the development of osteoarthritis. With increasing age, changed temporal dynamics of motor reflexes and reduced muscular force may affect the efficacy of neuromuscular protection of the knee joint. In three experimental studies conducted with osteoarthritis patients and healthy controls, no difference was found in monosynaptic reflex times and latencies of somatosensory evoked brain potentials. Muscular force was generally diminished in the patients, with the most prominent reduction during coxal abduction. Osteoarthritis patients had marked nociceptive hyposensitivity, but no difference was seen in fast conduction afferent systems. In an animal study with high locomotion load, interruption of articular afferent nerve fibers led to a precipitation of cartilage degeneration. It is concluded that minor extraarticular functional deficits acting over time, probably support and aggravate the development of osteoarthritic changes.

Aged↗

PubMed1993

Functional characterization of mitochondrial oxidative phosphorylation in saponin-skinned human muscle fibers.

The conditions of treatment of human skeletal muscle fibers from M. vastus lateralis with saponin were optimized to achieve complete permeabilization of cell membrane at intact mitochondrial oxidative phosphorylation. After 30 min of incubation with saponin all lactate dehydrogenase, 50% of creatine kinase, 30% of adenylate kinase and less than 20% of citrate synthase was released into the permeabilization medium. These skinned fibers behave similar to isolated mitochondria from human skeletal muscle: (i) the respiration with mitochondrial substrates can be stimulated by ADP, (ii) inhibited by carboxyatractyloside and (iii) it is possible to detect fluorescence changes of mitochondrial NAD(P)H on additions of substrates, uncoupler and cyanide. From a comparison of rates of respiration per cytochrome aa3 content of isolated human skeletal muscle mitochondria and saponin-skinned muscle fibers it was possible to calculate that almost 85% of mitochondria in those fibers are accessible for the investigation of oxidative phosphorylation. As shown by the investigation of biopsy samples of two patients with undefined myopathies these fibers are a suitable object for the replacement of isolated mitochondria in the diagnosis of mitochondrial myopathies and encephalomyopathies.

Animals↗

PubMed1989

[Prosthetic management of rotation-plasties according to Borggreve].

Two patients, suffering from Osteosarcoma of the distal femur, were operated in 1987. A Rotatoryplasty with resecting the half of the femur and the knee joint was performed. We would like to demonstrate our experiences in the prosthetic fitting in these patients. The Rotatoryplasty improves the prosthetic comfort in these patients cured by above knee amputation in former time.

Amputation, Surgical↗

PubMed1987