PubMed HealthSearch

Biomedical subjects

K Steffens

Publications and source records attributed to K Steffens.

17 recordsLinked to original sources

Training in basic microsurgical techniques without experiments involving animals.

Until recently, anaesthetised rats have been the usual material employed for learning basic microvascular and microneurosurgical techniques. However, ethical considerations, the costs involved and legislation controlling experiments with animals allow training in microsurgery for extended periods of time at a few medical centres only. This paper reports on our experience of an alternative training programme largely conducted without using live animals. As the basic material we selected legs of slaughtered pigs. According to the developing skill of the trainee, basic microsurgical techniques can be practised on arteries and veins of various sizes in these legs. To verify positive results, the vessels are subsequently perfused with human blood under pressure. The model described is particularly suited to the acquiring of skills in microneurosurgery. Mono-, oligo- and polyfascicular nerves, structurally similar to the configurations found in human extremities, are found in pig legs. The ever-increasing importance of microsurgery in modern medicine requires more and more surgeons and orthopaedists to familiarize themselves with these techniques. The model we propose for teaching and training substantially facilitate such further professional training in an efficient way, and at the same time allows a substantial reduction in the number of experiments conducted on animals.

Animal Testing Alternatives

[A realistic practice model for learning microneural surgery without experiments on live animals].

The increasing importance of microneurosurgery in hand and plastic surgery makes it necessary for surgeons to familiarize themselves with these techniques. In most training programs, anesthetized rats have been used to learn basic microneurosurgical techniques. Ethical considerations, the costs involved, and the legislation concerning experiments with live animals permit extensive training in microneurosurgery in only a few medical centers. This paper relates our experience with an alternative training program not involving live animals. Instead, we chose the legs of slaughtered pigs. Mono-, oligo-, and poly-fascicular nerves, structurally similar to the configurations found in human extremities, can be found in pig legs. Neurolysis, primary nerve sutures, and nerve transplantations can be practiced.

Animal Testing Alternatives

[Long-term spontaneous course of carpal instability].

The authors report on the natural history of 26 cases of carpal instabilities observed over a period of 25 to 74 months. Apart from the subjective criterion pain, the parameters range of motion and grip strength have been documented in the course of their development. In addition, radiographic findings have been evaluated. We confirm that carpal instabilities can lead to degenerative arthrosis. The expectation that there would be a progressive deviation from the norm of the angles between radius, scaphoid, lunate, and capitate bones measured in lateral radiographs did not prove to be true.

Adult

[Isolated compression of the dorsal branch of the ulnar nerve].

The dorsal branch of the ulnar nerve was dissected in 20 upper extremities. The nerve arises from the ulnar aspect of the ulnar nerve at an average distance of 8.5 centimeters from the proximal border of the pisiforme. It courses deep to the palmar carpal ligament and pierces the ligament dorsal to the tendon of the flexor carpi ulnaris, becoming subcutaneous. The palmar carpal ligament has been found to be a cause of isolated entrapment of the dorsal branch of the ulnar nerve. A report of eleven operative cases is presented.

Adult

[Determination of the endotoxin content of egg products using a miniaturized chromogenic Limulus test].

A chromogenic Limulus amoebocyte lysate assay was applied to monitor endotoxin concentration in egg products. Analysis of differently contaminated whole egg probes revealed a strong correlation of endotoxin concentration to total bacterial count 6 x 10(4) cfu x ng-1, where cfu = colony-forming unit) as well as to number of Enterobacteriaceae (1 ng/7 x 10(2) cfu). Similar relations were also found for egg white and egg yolk probes. A significant influence of heat pretreatment of egg probes (65 degrees C, 60 min) on endotoxin detection could be excluded. Up to a concentration of 10 mg x ml-1 endotoxin-free whole egg material did not interfere with the test system. A miniaturized version of the chromogenic Limulus test, which can be carried out in microtiter plates, is described.

Animals

[The supinator syndrome--an anatomical and clinical study].

The interosseus posterior syndrome appears in two forms: a) the paralytical interosseus posterior syndrome, b) the painful (afferent) interosseus posterior syndrome. We report in this investigation about 12 operated patients with painful interosseus posterior syndrome. The intraoperative findings in the arcade of Frohse are compared with the findings we made at the preparation of 10 recently deceased. It was especially significant, that we found in 10 of our 12 cases intraoperatively a tendinous type of arcade. In our directioned cases we encountered this type of tendinous arcade in only 2 of 10 cases. Based on these findings we are of the opinion that the tendinous arcade of Frohse is an important factor in the development of the interosseus posterior syndrome.

Adult

[The supinator syndrome. An anatomic and clinical study].

The posterior interosseous syndrome appears in two forms, a) paralytical, and b) painful. In this investigation the authors report on twelve operated patients with painful posterior interosseous or "radial tunnel" syndrome. The intraoperative findings in the arcade of Frohse are compared with the findings on preparation of ten recently deceased. It was especially significant that in ten of twelve cases there was found intraoperatively a tendinous type of arcade. In the cadaveric studies the authors encountered this type of tendinous arcade in only two of ten specimens. Based on these findings, the authors conclude that the tendinous arcade of Frohse is an important factor in the development of the posterior interosseous syndrome.

Adult

F0 part of the ATP synthase from Escherichia coli. Influence of subunits a, and b, on the structure of subunit c.

Four different sets of proteoliposomes were prepared from F0, subunit c, a complex of subunits a and c (ac complex) and an ac complex supplemented with subunit b. Only liposomes containing intact F0 or all subunits of F0 were active in proton translocation and F1 binding [Schneider, E. and Altendorf, K. (1985) EMBO J. 4, 515-518]. The conformation of subunit c in the different preparations was analyzed by labelling the proteoliposomes with the hydrophobic photoactivatable reagent 3-(trifluoromethyl)-3-(m-[125I]iodophenyl)diazirine ([125I]TID). Subsequent isolation and Edman degradation of this polypeptide revealed distinct radioactive labelling patterns over the entire amino acid sequence. In the F0 complex and in the ac complex subunit c retains a labelling pattern which is related to that found in TID-labelled membrane vesicles of Escherichia coli [Hoppe et al. (1984) Biochemistry 23, 5610-5616]. In the absence of subunit a, considerably more and different amino acid residues of subunit c are modified. The labelling data are discussed in relation to structural aspects of F0 and functional properties of proteoliposomes reconstituted with F0 or individual subunits.

Azirines

[Compression of the median nerve by chondrosarcoma of the hand].

The authors report a case of median nerve compression due to a chondrosarcoma of the wrist. A 30 year-old right handed man complained of typical symptoms of median nerve compression. X-ray examination showed normal findings. During operation a more proximal lumbrical origin was the only abnormal finding. After nerve decompression pain relief was prompt. Six months later the patient again complained of symptoms of median nerve compression. Now X-ray examination showed scattered punctuate calcific densities of dystrophic calcification. The tumor was histologically shown to be a chondrosarcoma. It was treated by wide local excision and radiation therapy.

Adult

[True trigger wrist (a case report)].

Clicking at the wrist, in association with movements of the fingers, has been commonly but erroneously called "trigger wrist". In true trigger wrist, triggering occurs only in relation to movements of the wrist. The authors report a case of true trigger wrist in a 23-year-old professional tennis player. Triggering was caused by a "synovial mass" around partially destroyed tendons of the ECRB, ECRL, and EPL at the level of the extensor retinaculum.

Adult

Structural and functional relationship of ATP synthases (F1F0) from Escherichia coli and the thermophilic bacterium PS3.

Functional compatibility between the F1 and F0 parts of ATP synthases from Escherichia coli (EF1F0) and the thermophilic bacterium PS3 (TF1F0) was analyzed. F1-stripped everted membrane vesicles from both organisms bound the homologous or heterologous F1 part to the same extent. Titration of the reconstituted membrane vesicles with dicyclohexylcarbodiimide revealed a similar sensitivity of the homologous and hybrid F1F0 complexes towards the inhibitor. Furthermore, the heterologous enzymes exhibited ATP-dependent H+ translocation comparable to that of homologous F1F0. Antisera raised against EF1 or subunits a, b, and c of EF0 were analyzed for cross-reactivity with TF1 and TF0. Common antigenic sites have been detected with immunoblot analysis for subunit beta and subunit c of EF1F0 and the corresponding subunits from TF1F0. A weak binding of the anti-a and anti-b antisera with the TF0 part has been observed in an enzyme-linked immunosorbent assay. Based on these findings the structural and functional relationship between the mesophilic and thermophilic ATP synthase complexes is discussed.

Cross Reactions

Fo portion of Escherichia coli ATP synthase. Further resolution of trypsin-generated fragments from subunit b.

F1-stripped everted membrane vesicles of the ATP synthase-overproducing Escherichia coli strain KY 7485 were treated with trypsin for different lengths of time. Subsequently, the Fo complex was isolated and analyzed by sodium dodecyl sulfate-gel electrophoresis, as well as immunoblotting using antibodies raised against subunit b. By these techniques 3 degradation products with apparent molecular masses of about 16 kDa could be detected in accordance with previous findings (Perlin, D.S., and Senior, A.E. (1985) Arch. Biochem. Biophys. 236, 603-611). Labeling of isolated trypsin-treated Fo fractions with the thiol-specific reagent N-(7-dimethylamino-4-methylcoumarinyl)-maleimide, which has been demonstrated recently to specifically modify subunit b (Schneider, E., and Altendorf, K. (1985) Eur. J. Biochem. 153, 105-109) revealed that the 16-kDa digestion products were degraded into two stable fragments of 12 and 8.3 kDa. These polypeptides do not react with the anti-b antibodies. Treatment of purified liposome-integrated Fo with trypsin resulted in a similar cleavage pattern. In both cases protease digestion inhibited F1 binding while proton-translocating activity remained unaffected. However, liposomes reconstituted with Fo isolated from trypsin-treated membranes were impaired in both binding of F1 and proton translocation. These activities could be restored when reconstitution was carried out in the presence of native subunit b. From this we conclude that the C-terminal region of subunit b is necessary for proper reconstitution of Fo into liposomes.

Cell Membrane

Evolutionary relationship between Enterobacteriaceae: comparison of the ATP synthases (F1F0) of Escherichia coli and Klebsiella pneumoniae.

The ATP synthase complex of Klebsiella pneumoniae (KF1F0) has been purified and characterized. SDS-gel electrophoresis of the purified F1F0 complexes revealed an identical subunit pattern for E. coli (EF1F0) and K. pneumoniae. Antibodies raised against EF1 complex and purified EF0 subunits recognized the corresponding polypeptides of EF1F0 and KF1F0 in immunoblot analysis. Protease digestion of the individual subunits generated an identical cleavage pattern for subunits alpha, beta, gamma, epsilon, a, and c of both enzymes. Only for subunit delta different cleavage products were obtained. The isolated subunit c of both organisms showed only a slight deviation in the amino acid composition. These data suggest that extensive homologies exist in primary and secondary structure of both ATP synthase complexes reflecting a close phylogenetic relationship between the two enterobacteric tribes.

Biological Evolution

[Doppler sonography alone in the preoperative planning of free flap transplantations].

Successful transplantation of a free flap is dependent on a thorough knowledge of the circulatory conditions of the donor and the recipient sites. The Allen-test is not feasible in all cases and is not always dependable. Angiography is not only a strain for the patients but often involves risks. This paper gives an account of the Doppler-sonography investigation method based on documented studies of the radial and ulnar arteries and of the anterior and posterior tibial arteries. This method involves no strain on the patients and allows for precise assessment of the circulatory conditions of the donor and recipient sites.

Forearm

Conformation-specific antiserum raised against subunit c of ATP synthase (F1F0) from Escherichia coli.

Subunit c of the membrane-integrated, proton-translocating F0 portion of the ATP synthase (F1F0) from Escherichia coli has been isolated under nondenaturing conditions (Schneider, E., and Altendorf, K. (1985) EMBO J. 4, 515-518) and antibodies have been raised in rabbits. The primary antisera did not recognize the antigen when present in the same buffer as used for the immunization. Surprisingly, in one of the three antisera a strong antibody binding was observed when intact F0, a.c complex or reconstituted subunit c was provided as the antigen. Incorporation of subunit c into liposomes together with subunits a and b forming an active, H+-translocating complex was not required for the recognition by the antiserum. Subunit c prepared by chloroform/methanol extraction or by chromatography in the presence of sodium dodecyl sulfate was not recognized by the anti-c antiserum when incorporated into liposomes.

Antigen-Antibody Complex