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Biomedical subjects

K Küper

Publications and source records attributed to K Küper.

At least 19 recordsLinked to original sources
PubMed1999

[Allogenic heterotopic cartilage transplantation for primary corneal replacement in a rabbit model].

BACKGROUND: Aim of the present study was to investigate woundhealing after allogen heterotopic cartilage transplantation in a rabbit model. MATERIAL AND METHODS: Cartilage discs were transplanted by central lamellar keratoplasty (diameter 5.0 mm) in eleven New Zealand White Rabbits. Cartilage was harvested of the ears of rabbits at the day of transplantation. The cartilage discs 0.5-0.6 mm thick were prepared with 5.2 mm diameter and transplanted within 12 hours. Fixation was performed by eight 10-0 nylon sutures. Postoperatively, dexamethasone ointment containing gentamicin was applied three times a day for three weeks. Clinical course was documented by photographs. For histological examinations the transplanted eyes were enucleated after one day or three days, and after 3, 6 or 12 months. RESULTS: Allogen cartilage healed firmly in the cornea within two months. During the course of observation the cartilage grafts thinned and were replaced by normal appearing collagen fibrills. In one case neovascularisation of the cornea occurred and reached the cartilage graft, but did not invate. Histologically, in all cases no leukocytes could be seen in the cartilage or its neighbourhood. The cartilage grafts did not proliferate and remained avascular. The intraocular structures showed no inflammatory reaction. CONCLUSIONS: Allogen cartilage grafts to a clear corneal pounch do not induce an inflammatory reaction. Therefore, autologous cartilage prepared of ears seems to be useful biological material in ophthalmologic surgical procedures, for example to fill up corneal defects. To investigate if cartilage grafts will be helpful to stop neovascularisation in keratoplasty further studies with vascularisized corneas are necessary.

Animals↗
PubMed1997

[Lymphangioma of the conjunctiva].

A 23-year-old female presented with a yellow-brownish, asymptomatic tumour of the bulbar conjunctiva in her left eye. The lesion had been detected 5 years previously and had grown since then. Prior to presentation there were 2 episodes of intratumoral hemorrhage. Funduscopy revealed tortuous vessels on the left. Complete tumour excision was performed. Histology showed numerous channels lined by a flat endothelium, and inflammatory cells in the fibrous septae. A diagnosis of a conjunctival lymphangioma was established. The tortuosity of the retinal vessels was probably associated by chance or caused by an undetected orbital lymphangioma.

Adult↗
PubMed1995

[Erythema exsudativum multiforme major].

UNLABELLED: Erythema exudativum multiforme major (EEMM), also know as Stevens-Johnson syndrome, may cause severe conjunctival and corneal alterations. The etiology remains unknown. The aim of are study was to evaluate the clinical course, therapy and prognosis of ocular involvement. PATIENTS AND METHODS: In a retrospective study, we evaluated ten patients with EEMM who were treated between 1986 and 1994 at the University Eye Clinic Tübingen. RESULTS: The age of the four female and six male patients varied between 5 and 70 years. Drugs as a possible precipitating factor were found in all cases (acetylsalicylicacid, sulfonamide, erythromycin, cotrimoxazole, Valproinicacid, paracetamol). Eight patients experienced an infection at the same time. Clinically, we were able to differentiate two groups regarding severity of the disease. Seven patients were characterized by ocular alterations that only involved the conjunctiva, leading to conjunctival scars. In those cases local treatment with antibiotics and corticosteroids was effective. In the second group severe ocular damage occurred, with symblephara, keratinization and consecutive perforating keratoplasty. Secondary infections became evident in a total of six cases from the two groups. SUMMARY: Drugs as a possible precipitating factor could be identified in all cases. In eight of ten patients previous infection was known. This agrees with literatures reports of viral infections (e.g. herpes simplex) as cofactors causing EEMM, especially for the aggressive form, remains unresolved. The danger of possible superinfection should always be taken into consideration.

Adolescent↗
PubMed1994

Spin-echo methods for the determination of 31P transverse relaxation times of the ATP NMR signals in vivo.

31P magnetic resonance spectroscopy (MRS) examinations of the calf muscles of healthy volunteers were performed to determine T2 of the coupled ATP signals by use of the Hahn spin-echo and the frequency-selective spin-echo method. Additional measurements with the J-coupling refocused double echo are presented. The most reliable determination of T2 relaxation times is possible with the frequency-selective spin echo. The other methods yield substantially wrong results. Theoretical explanations are given how J-coupling and pulse-angle deviations affect the signals and therefore the T2 determinations. The calculations for a weakly coupled homonuclear AX spin system are shown because they demonstrate most of the relevant facts. In addition, some important results for a homonuclear AMX spin system, which the ATP is considered to be, are given.

Adenosine Triphosphate↗
PubMed1994

[Diffuse xanthogranuloma as a cause of infantile heterochromia].

A 7-month-old female infant presented with a heterochromia and an anisocoria. A spontaneous hyphema and a secondary glaucoma had developed. Under topical and systemic steroid therapy the eye improved continuously. At the time of the last ocular examination the hyphema had resorbed, and the intraocular pressure was normal. Heterochromia had almost completely vanished, and dilation of the pupil was much better. Since even a massive juvenile xanthogranuloma of the iris responds well to steroids, operative and radiation treatment should be limited to cases refractory to antiinflammatory drug therapy.

Administration, Oral↗
PubMed1993

A pitfall associated with determination of transverse relaxation times of the 31P NMR signals of ATP using the Hahn spin-echo.

T2 measurements of 31P NMR signals of ATP using the Hahn 90 degrees-180 degrees spin-echo sequence imply difficulties whenever the 180 degrees pulse angle is not completely perfect. The reason for this finding is the crucial influence of the J-couplings of the ATP signals which result in intensity modulations and consequently in false T2 values even when the echo times are chosen to TE = n/J. Examinations on the calf muscles of healthy volunteers were performed to demonstrate this effect and its influence on in vivo T2 determinations. The T2 relaxation times evaluated with the Hahn spin-echo in combination with a Helmholtz coil are far shorter than the true T2 values.

Adenosine Triphosphate↗
PubMed1993

31P transverse relaxation times of ATP in human brain in vivo.

31P MRS examinations of the brain of 10 healthy volunteers were performed to determine T2 of the coupled ATP signals by use of the localized 90 degrees-TE/2-2662-TE/2-acq frequency selective spin echo sequence for elimination of phase and intensity distortions. The T2 relaxation times obtained are much longer than usually assumed: gamma-ATP: 89 +/- 9 ms; alpha-ATP: 84 +/- 6 ms; beta-ATP: 62 +/- 3 ms.

Adenosine Triphosphate↗
PubMed1993

Imaging of the human cardiovascular system using the rapid echo flow-rephased spin-echo technique.

Using a flow-rephased spin-echo technique with a short echo time of TE = 9.7 msec, "white blood" multislice and single slice first echo images of the human heart were acquired using standard 1.5 T whole-body imagers. The technique almost completely eliminates phase shifts for flow with constant velocity and constant acceleration, so the investigations with healthy volunteers show images which are almost free of the artifacts often found in ECG-gated standard spin-echo imaging of the heart. T1-weighted images with good contrast between tissue and blood are achieved at any time during the whole heart cycle. The results obtained indicate that the technique might be helpful for imaging small vessels, vessels which contain slowly flowing blood, and vessels located in regions with static field inhomogeneities, for example, lung vessels.

Adult↗
PubMed1992

31P transverse relaxation times of the ATP NMR signals of human skeletal muscle in vivo.

31P MRS examinations of the calf muscles of 12 healthy volunteers were performed to determine T2 of the coupled ATP signals by using the 90 degrees-TE/2-2662-TE/2-acq selective spin-echo sequence for elimination of phase and intensity distortions. The T2 relaxation times obtained are much longer than those usually assumed: gamma-ATP, 93 ms; alpha-ATP, 74 ms; beta-ATP, 75 ms.

Adenosine Triphosphate↗
PubMed1992

Localized phosphorus NMR spectroscopy: a comparison of the FID, DRESS, CRISIS/CODEX, and STEAM methods in vitro and in vivo using a surface-coil.

The FID, DRESS, CRISIS/CODEX, and STEAM techniques for localized 31P NMR spectroscopy were compared using a Siemens Magnetom SP63 1.5 T whole-body imager and a surface-coil, 80 mm in diameter, acting as transmitter and receiver coil. The comparison was performed with phantom experiments and human in vivo investigations on the calf muscle. The phantom experiments which used the same volume size showed a comparable signal-to-noise ratio for FID and DRESS, while the two fully localized techniques showed a reduction in signal-to-noise ratio to 76% for CRISIS/CODEX and 31% for STEAM. The in vivo measurements confirm the phantom results and reveal that CRISIS/CODEX gains a 2.5 fold higher signal-to-noise ratio than STEAM under the same conditions.

Humans↗
PubMed1989

[NMR tomography of the shoulder joint: clinical experiences with the saturation pulse technic].

High zoom factors for MRT of the shoulder joint can lead to disturbing artifacts. The use of special saturation coils can improve longitudinal magnetisation of the central image, making it possible to produce artifact-free images of the shoulder with high resolution. Two normals and 20 patients with the rotator cuff syndrome, as well as other inflammatory and neoplastic processes, have been examined. The findings have been correlated with those of arthrography, arthro-sonography, bone scintigraphy, CT and simple radiographic examination. The MRT findings were compared with the other imaging techniques and the results are discussed. MRT proved superior to other techniques, particularly in the elucidation of soft tissue abnormalities in the rotator cuff syndrome.

Adolescent↗
PubMed1989

[T2*-weighted MR images of gynecologic tumors with the FLASH sequence: the initial experiences at 1.5 T].

To speed up the time taken for MR examinations, 20 patients with malignant gynaecological lesions (carcinoma of the cervix, uterus or ovary) and two operative specimen (carcinoma of the cervix) were examined by T2*-weighted flash sequences; the results were compared with T2-weighted spin echo sequences. In ten out of 20 in vivo examinations, the flash method produced a similar contrast range between tumour and normal tissues, cystic lesions being particularly well seen in gradient echo sequences. In the remaining patients, and in the surgical specimen, demarcation of the tumour was significantly poorer on the flash sequences. There was also loss of anatomic detail and an increased susceptibility to artifacts. The flash sequence as used here can therefore not be regarded as of the same diagnostic value as T2-weighted spin echo sequences in the diagnosis of gynaecological malignancies.

Carcinoma↗
PubMed1988

[Optimized study technic in meniscopathies by NMR tomographic 3D imaging at 1.5 tesla].

Traumatic and degenerative changes in the meniscus can be demonstrated well by MRT, but the small size and complex anatomical structure of the menisci present practical problems. A correct understanding is only possible by images in several planes and good resolution, making the examination a lengthy procedure. A technique is therefore described using 3-D images and reconstruction of high-resolution films, which allows rapid examination of the menisci in optimal planes.

Cartilage Diseases↗
PubMed1988

[Parameter-weighted MR images and their optimization: theory and example of images for the flash sequence compared to the spin-echo sequence].

In this paper the signal intensity and parameter-weighting zones of spin echo and gradient echo sequences (FLASH) have been analysed. Using information available in the literature, with additional analytical and numerical techniques, it is possible to determine parameters which maximise tissue contrast for T1, T2 and proton-weighted images. The technique is equally applicable to spin echo and FLASH sequences. The advantages of optimised gradient echo sequences compared with spin echo sequences with respect to its signal to noise ratio for short repetition times are analysed quantitatively. T2-weighted images can be generated as rapid as T1-weighted images, using the FLASH sequences when using a small angle of spin and relatively long echo. Illustrations are shown to demonstrate the numerical results (field strength 1.5 tesla). This is followed by a discussion of possible opposing effects.

Humans↗
PubMed1988

[Technics of secondary reconstruction of planar images from magnetic resonance tomographic 3D data sets].

Description of a method to reconstruct planar images from MRT 3D data sets. These images can be of varying orientation. Reconstruction requires a computer and the control panel of a normal magnetic resonance tomography equipment. Calculation of reconstruction is done in a few minutes. Patients can be examined parallel to this without difficulty. The method yields in a much shorter time than before images with a definitely higher resolution than by the conventional technique.

Humans↗