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R Schmitt

Publications and source records attributed to R Schmitt.

At least 37 records · Page 2Linked to original sources
PubMed2002

[Scapholunate ligament tears in MR arthrography compared with wrist arthroscopy].

In a blinded study from January to July 2000, 125 patients suffering from specific complaints of the wrist were prospectively examined with direct MR arthrography. Within 24 hours an arthroscopy of the wrist was performed. With MR arthrography in 21 patients or 17 % of all patients, injury of the scapho-lunate ligament was diagnosed. In all patients this could be verified arthroscopically. In the remaining 104 patients, no SL-ligament lesions were diagnosed with the MR arthrography. However, partial lesions were found via arthroscopy in seven cases and complete lesions of the ligament were found in one case, where MRI findings expected an intact SL ligament. In the remaining 96 cases, the MRI could correctly exclude a lesion of the SL-ligament. The diagnosis of a SL-ligament lesion by means of MRI was correct in 100 % of the cases (specificity), the exclusion of such lesions in 72 % (sensitivity). Positive or negative predictive values of 100 % or 92 % were achieved. Since a sensitivity of 100 % cannot be reached at the moment, MR arthrography cannot replace arthroscopy. However, it could be a potent additional tool for wrist diagnosis if intraarticular contrast is used. It can facilitate the diagnostics and the indication for surgery of the wrist and help to reduce arthroscopic interventions for purely diagnostic purposes and without any therapeutic consequences. With improvement of the technique of magnet resonance tomography we can expect a further increase of accuracy in the clinical use of the MR arthrography in the diagnostic workup of the wrist.

Adult↗
PubMed2002

Simultaneous ERP and event-related fMRI: focus on the time course of brain activity in target detection.

The event-related P300 potential has been widely used in neurophysiological research. It is usually evoked with an oddball paradigm. One main reason for its broad application in neurophysiological research is the fact that in several brain/mental diseases, such as Alzheimer's disease or schizophrenia, attenuations of the P300 amplitude and latency have been described. However, a precise correlation of the scalp data to the underlying brain regions was not possible, as the correct localization of the generators of scalp-measured electroencephalogram (EEG) data was limited, due to the low spatial resolution of EEG-data. With the availability of modern imaging technologies, functional Magnetic Resonance Imaging (fMRI) in particular, the underlying brain activations could be detected using an oddball task. Although the spatial resolution of fMRI is excellent, the time resolution is restricted. For a comprehensive understanding of the brain activity underlying the P300 paradigm, we have used a combination of EEG and fMRI to get a precise localization and a high-time resolution of the underlying brain activity.

Acoustic Stimulation↗
PubMed2001

Two enhancers and one silencer located in the introns of regA control somatic cell differentiation in Volvox carteri.

The regA gene plays a central role in germ-soma differentiation of Volvox carteri by suppressing all reproductive functions in somatic cells. Here we show that the minimal promoter of regA consists of only 42 bp immediately upstream of the transcription start site, and that it contains no discernible regulatory elements. However, introns 3 and 5 are both required for regA expression in somatic cells, and intron 7 is essential for silencing regA in gonidia (asexual reproductive cells). A regA gene lacking intron 7 rescues the normal phenotype of mutant somatic cells, but also results in gonidia that reproduce only weakly and soon die out. The same phenotype is observed when a regA gene containing intron 7 is placed under control of a constitutive promoter, suggesting that the silencing activity of intron 7 is promoter specific. Intron 7 is unusual in that it contains a potential ORF that is in frame with exons 7 and 8, and some transcripts are produced in which intron 7 is retained. However, a regulatory role for the intron 7 translation product can be ruled out, because a construct in which intron 7 must be translated, and one in which it cannot be translated, both result in wild-type development of both cell types. Furthermore, intron 7 is unable to act in trans to silence regA, but is able to exert its normal effect when placed in a different location within the gene. Therefore, it appears that intron 7 functions in gonidia as a classical cell-type-specific and promoter-specific enhancer, of the inhibitory type that is often referred to as a silencer.

3' Untranslated Regions↗
PubMed2001

A link between DNA methylation and epigenetic silencing in transgenic Volvox carteri.

Epigenetic silencing of foreign genes introduced into plants poses an unsolved problem for transgenic technology. Here we have used the simple multicellular green alga VOLVOX: carteri as a model to analyse the relation of DNA methylation to transgenic silencing. VOLVOX: DNA contains on average 1.1% 5-methylcytosine and 0.3% N6-methyladenine, as revealed by electrospray mass spectrometry and phosphoimaging of chromatographically separated (32)P-labelled nucleotides. In two nuclear transformants of V.carteri, produced in 1993 by biolistic bombardment with a foreign arylsulphatase gene (C-ars), the transgene is still expressed in one (Hill 181), but not in the other (Hill 183), after an estimated 500-1000 generations. Each transformant clone contains multiple intact copies of C-ars, most of them integrated into the genome as tandem repeats. When the bisulphite genomic sequencing protocol was applied to examine two select regions of transgenic C-ars, we found that the inactivated copies (Hill 183) exhibited a high-level methylation (40%) of CpG dinucleotides, whereas the active copies (Hill 181) displayed low-level (7%) CpG methylation. These are average values from 40 PCR clones sequenced from each DNA strand in the two portions of C-ars. The observed correlation of CpG methylation and transgene inactivation in a green alga will be discussed in the light of transcriptional silencing.

5-Methylcytosine↗
PubMed2001

[Stener lesion yes or no? Diagnosis by ultrasound].

25 patients with clinical signs for ulnar collateral ligament injury to the metacarpophalangeal joint of the thumb were examined by ultrasonography before operation to verify Stener's lesion. The results were compared with intraoperative findings. In 18 patients (74%), ultrasound and surgical exploration yielded equivalent results. Seven patients showed signs of Stener's lesion in ultrasound that could not be verified during surgery. No Stener's lesion was missed.

Adult↗
PubMed2001

[Experiences with the STT (scapho-trapezio-trapezoid) arthrodesis. A retrospective evaluation].

From 1992 until 1998, 98 fusions of the scapho-trapezio-trapezoid joint on 97 patients were performed in our clinic. The indications were dissociation of the scapho-lunate joint (n = 32), necrosis of the lunate stage III/IV (Lichtman classification) (n = 39), and idiopathic arthrosis of the scapho-trapezio-trapezoid joint (n = 27). 87 patients with 88 procedures were reviewed after an average follow-up period of three years. The review included a clinical examination with determination of a traditional wrist-score and a DASH questionnaire, X-rays of the wrist and CT of the carpal bones. The results in the wristscore were on average 74 of maximal 100 points. The DASH-score was on average 29. The best results were in the group with arthrosis of the scapho-trapezio-trapezoid joint. The results in the groups with scapho-lunate dissociation and necrosis of the lunate were also good. The rate of non-union was within an acceptable level with 7.7%. In the examined group, five patients underwent fusion of the wrist for persisting pain after scapho-trapezio-trapezoid arthrodesis. The examination of the radiological investigations in the reviewed group demonstrated, that CT shows arthritic degeneration in patients where the conventional X-ray does not. In conclusion, scapho-trapezio-trapezoid arthrodesis is a valid therapeutic method in the above mentioned indications. However, the question how early arthritic degeneration will affect long-term results remains unanswered for the moment.

Adolescent↗
PubMed2001

[Radiologic diagnosis of lunate necrosis].

In the literature little is to be found concerning diagnosis and differential diagnosis of Kienböck's disease. Because of technical development in radiological imaging, we now possess very detailed pictures. However, there are many radiological findings within the lunate bone, which can be misinterpreted as Kienböck's disease. Pathological findings of the lunate bone are demonstrated, which are not Kienböck's disease. These findings were compared to different stages of Kienböck's disease and identified. The early stages of Kienböck's disease show changes especially in the MRI, which are very similar to acute bone bruise, ulnar impaction syndrome, synovialitis or gout. Vessel tubes or an intraosseous ganglion can be mistaken for Kienböck's disease. In the late stages of Kienböck's disease, it can be difficult to differentiate this from pseudarthrosis of the lunate bone. The differentiation between Kienböck's disease and other pathological findings is at times very difficult--even with MRI. However, sometimes diagnosis can only be verified by MRI. We therefore suggest that Kienböck's disease must be correctly diagnosed with help of the MRI before commencing with any therapeutic steps.

Diagnosis, Differential↗
PubMed2001

Mutational analysis of the Rhizobium lupini H13-3 and Sinorhizobium meliloti flagellin genes: importance of flagellin A for flagellar filament structure and transcriptional regulation.

Complex flagellar filaments are unusual in their fine structure composed of flagellin dimers, in their right-handed helicity, and in their rigidity, which prevents a switch of handedness. The complex filaments of Rhizobium lupini H13-3 and those of Sinorhizobium meliloti are composed of three and four flagellin (Fla) subunits, respectively. The Fla-encoding genes, named flaA through flaD, are separately transcribed from sigma(28)-specific promoters. Mutational analysis of the fla genes revealed that, in both species, FlaA is the principal flagellin and that FlaB, FlaC, and FlaD are secondary. FlaA and at least one secondary Fla protein are required for assembling a functional flagellar filament. Western analysis revealed a ratio close to 1 of FlaA to the secondary Fla proteins (= FlaX) present in wild-type extracts, suggesting that the complex filament is assembled from FlaA-FlaX heterodimers. Whenever a given mutant combination of Fla prevented the assemblage of an intact filament, the biosynthesis of flagellin decreased dramatically. As shown in S. meliloti by reporter gene analysis, it is the transcription of flaA, but not of flaB, flaC, or flaD, that was down-regulated by such abortive combinations of Fla proteins. This autoregulation of flaA is unusual. We propose that any combination of Fla subunits incapable of assembling an intact filament jams the flagellar export channel and thus prevents the escape of an (as yet unidentified) anti-sigma(28) factor that antagonizes the sigma(28)-dependent transcription of flaA.

Amino Acid Sequence↗
PubMed2001

Traumatic disruption of a fibrocartilage lunate-triquetral coalition--a case report and review of the literature.

Whilst osseous coalitions of the lunate and the triquetrum are known to be asymptomatic, fibrocartilage lunate-triquetral coalitions can present an uncommon cause for ulnar-sided wrist pain. To diagnose this condition a high degree of suspicion is needed. We present a case with painful post-traumatic disruption of a fibrocartilage lunate-triquetral coalition that was primary misdiagnosed to be a disruption of the interosseous lunotriquetral ligament and was initially treated arthroscopically. Persistent symptoms lead to X-ray examination of the opposite wrist, revealing a complete osseous lunate-triquetral coalition. CT and MRI investigations demonstrated the fibrocartilage coalition of the affected wrist. Subsequently, lunotriquetral fusion using a cannulated Herbert screw was performed and settled the symptoms completely.

Accidents, Traffic↗
PubMed2001

[MR angiography of pelvic and leg arteries: initiation with time-resolved data acquisition of the lower legs].

58 patients suffering from peripheral arterial vascular disease were examined using contrast-enhanced MR angiography with the intention of optimizing the visualization of lower leg arteries. Different from the customary acquisition order, were first the arteries of the lower legs depicted with three time-resolved phases. Afterwards, the iliacal and femoral vessels were imaged by applying the floating-table technique in two steps. In all cases, the lower leg arteries were depicted without overlying veins. By injecting the contrast agent in two phases, imaging quality of the iliofemoral arteries was not significantly reduced.--In conclusion, we would recommend the hybrid technique of peripheral contrast-enhanced MRA with primarily starting the acquisition of the lower legs in cases of foot infections or ulcerations where the transit time is reduced bi- or unilaterally.

Adult↗
PubMed2001

[Multi-slice spiral CT of the coronary arteries: clear vascular imaging using standard software].

OBJECTIVE: To visualize the coronary arteries with a clear view and over a long distance by using data sets from contrast-enhanced computed tomography of the heart. MATERIAL AND METHODS: Image data of 151 patients suffering from coronary artery disease were calculated by means of retrospective triggering at four different diastolic delay times in contrast-enhanced CT. The large coronary segments were subsequently reconstructed in two planes with multiplanar volume reconstruction (MPVR)--a non-dedicated postprocessing software. RESULTS: On the pre-condition that data sets were acquired at sinus rhythm and at a heart beat rate lower than 65/min coronary arteries could be depicted over a long distance in single or double angulated reconstruction planes with the help of multiplanar volume reconstruction (MPVR). Time consumption for image reconstruction was reasonable. Additionally to the anatomy of the coronary arteries in two different planes, typical CT findings in occluding coronary artery disease are presented. CONCLUSION: Multiplanar volume reconstruction (MPVR) implemented on most workstations is a powerful and ideal postprocessing tool in reconstructing coronary arteries from contrast-enhanced CT data sets.

Coronary Angiography↗
PubMed2000

[Scaphoid fractures--diagnosis, classification and therapy].

Herbert's classification of scaphoid fractures provides the underlying rationale for treatment according to the fracture type. A CT bone scan in the long axis of the scaphoid is the best means of differentiating between stable and unstable fractures. This is difficult from conventional X-rays due to the particular three-dimensional anatomy of the scaphoid. To avoid long-term plaster immobilization and to diminish the risk of a nonunion, unstable fractures of type B should be fixed operatively. With headless screws such as the Herbert screw, which are now available in a cannulated shape, the majority of scaphoid fractures of type B1 and B2 can be stabilized using minimally invasive procedures. Severely displaced fractures require the classical open palmar approach. Proximal pole fractures (B3) are best managed from the dorsal approach, using the Mini-Herbert screw. Stable fractures of type A2 can be treated conservatively in a below-elbow cast or, alternatively, stabilized percutaneously, which allows early mobilization.

Bone Screws↗
PubMed2000

In vitro synchronization of embryonic mouse incisor preodontoblasts and preameloblasts: repercussions on terminal differentiation.

Preodontoblasts divide asynchronously and their terminal differentiation occurs gradually. Experimental data suggested that the expression of competence by preodontoblasts to respond to specific epigenetic signals, triggering their overt differentiation, requires a minimal number of cell cycles. The intrinsic timing mechanism could imply division counting and preodontoblasts of juxtaposed cell generations might sequentially withdraw from the last physiological cycle. To test such an hypothesis, embryonic mouse lower incisors were cultured in vitro and treated sequentially with nocodazole in order to induce a transitory synchronization of the dividing preodontoblasts and preameloblasts. This synchronization led to a disorganization of the physiological gradual terminal differentiation of the odontoblasts, giving rise to three distinct domains comprising respectively: 1) odontoblasts with altered polarization and predentin secretion; 2) odontoblasts demonstrating equivalent polarization and predentin deposition; and 3) preodontoblasts-odontoblasts involved in gradual terminal differentiation. These results strongly suggest that the gradient of odontoblast functional differentiation results from sequential withdrawal from asynchronous cell cycles of competent cells able to overtly differentiate.

Ameloblasts↗
PubMed2000

[Bursitis of the ulnar recess].

We investigated 20 patients suffering from wrist pain accompanied by local swelling of the recessus ulnaris. Pain could be produced by direct pressure to the recessus ulnaris or by rotation of the forearm during prehension grip. One group (n = 14) had no previous operation or trauma. A second group (n = 6) had undergone previous surgery or suffered from trauma. All patients were treated by injection of cortisone and lidocaine into the recessus ulnaris. In the first group, ten (71%) remained pain-free during a period of 19 (9 to 40) months. In the second group, no improvement could be achieved. Based on anatomy and evolution of the recessus ulnaris, we try to establish a theory of the pathology.

Adult↗