Biomedical subjects

B Waldecker

Publications and source records attributed to B Waldecker.

41 records · Page 3Linked to original sources

PubMed1983

[Prolapse of the lumbar vertebral disk--correlation of CT and myelographic findings with surgical findings].

Side by side with myelography, computed tomography is growing in importance as far as the diagnosis of the lumbar compression syndrome is concerned. From May 1980 to the end of April 1982, the authors employed at the Cologne University Clinic of Orthopaedics in 176 patients operated either for the first time or several times, myelography alone in 54 cases, and myelography combined with computed tomography in 98 cases, whereas computed tomography alone was used 24 times, in each case for the purpose of preoperative diagnosis. An epicritical analysis of the two last-named groups of examinations, basing on the findings made as a result of the operation, showed that computed tomography was superior in respect of the accuracy in determining the level and affected side of the compression. Two CT examinations only could not be utilised for technical reasons. Nine false-positive or false-negative cases (plus two examinations which were useless for technical reasons) were seen among the 98 myelographies of the patient group in question. Besides the equivalent information given by computed tomography in respect of the level and side of the compression, CT supplies additional information regarding constriction of the vertebral canal, defined osseous stenoses, preference for a particular side and site of prolapsed disk tissue, and on the cause of the compression in case there is a considerable stoppage of contrast medium. Computed tomography is better suited than myelography in the immediate postoperative phase for follow-up examinations which are aimed at differentiating renewed prolapses, haemorrhages, or cicatrised changes. Provided there is enough capacity for examination, it seems possible that the noninvasive computed tomography will eventually replace invasive myelography as a routine examination method in case of relevant indications.

Diagnostic Errors↗

PubMed1983

[Surgically verified CT findings after previous lumbar discotomy].

Our experience has shown that computed tomography is superior to myelography as a diagnostic tool after lumbar discotomy. Provided the examination is carried out correctly, CT has always supplied a precise anatomic diagnosis in cases where the myelogram was ambiguous. In particular, it was possible to differentiate between discogenic, cicatrized, haematoma-conditioned and osseous compression. However, two facts have to be reiterated: 1. The reference method in the cases under report was exclusively the surgical finding, representing a relatively clearly defined part of the patient material. 2. It goes without saying that the indication for a repeat operation must be based on the clinical findings as well.

Adult↗

PubMed1982

Comparison of the antiarrhythmic activity of mexiletine and lorcainide on ventricular arrhythmias.

In a blind cross-over study, 12 patients with ventricular arrhythmias (VPC's; Lown Grades II-IVB) resistant to a daily dose of quinidine 1.2 g, disopyramide 0.8 g, N-propyl-ajmaline 0.1 g were randomly given, each dose for one week, placebo (PL), mexiletine (MEX; 400, 600, 800 mg daily) and lorcainide (LOR; 200, 300, 400 mg daily). On the last day of each treatment period, patients were evaluated by 24-h continuous ambulatory monitoring, 6-channel surface ECG, plasma concentrations and side-effects. During PL I (before) and PL II (after drug treatment), the mean number of VPCs per hour was 670 and 701. VPCs were reduced in 5 of the 12 patients with MEX by 43% (400 mg), 74% (600 mg) and 91% (800 mg). VPCs were reduced in 10 patients with LOR by 60% (200 mg), 78% (300 mg) and 93% (400 mg). Log. lin. plasma conc. effect relationships were constructed for MEX and LOR. Vomiting, nausea, and abdominal pain were seen in 2 patients with MEX; insomnia and feeling heat in 10 patients with LOR. At the end of the LOR-treatment, these side-effects were less in 5 and absent in 5 patients. In this study, LOR seems superior to MEX in refractory ventricular arrhythmias.

Adult↗

PubMedDate not supplied

[Computerized tomography in lumbar compression syndrome].

Computertomography has been shown to be a reliable method for evaluation of lumbar compression syndromes. Excellent apparative equipment and differentiated examination techniques are required. As compared with myelography CT offers the advantages of a non-invasive procedure. Due to simultaneous axial visualisation of bone and soft tissue all components contributing to lumbar compression syndromes are included. This so far cannot be achieved by conventional radiographic methods. CT is superior to myelography concerning specificity and sensitivity of the diagnosis of primary and surgically treated herniated discs. It demonstrates extreme lateral dislocation of disc tissue as well as centrally located disc material at the L5/S1 level. Furthermore, compressing structures such like monosegmental osseous stenosis and stenosis of the spinal canal are well to be recognized. Tumors may be ruled out. Verification of postoperative hematoma and scar formation is of high clinical value. Myelography, however, remains being the method of choice when clinical symptoms are not to be appointed to a certain segment.

Diagnosis, Differential↗

PubMedDate not supplied

Blockade of Ca2+-activated K+ channels inhibits proliferation of human endothelial cells induced by basic fibroblast growth factor.

Basic fibroblast growth factor (bFGF) exerts angiogenic and mitogenic properties in human tissue. Since changes in ion currents modulate essential Ca2+-dependent intracellular pathways in endothelial cells, we have investigated a possible contribution of Ca2+-activated K+ channels (BKCa) on bFGF-induced endothelial cell proliferation. The patch-clamp technique was used to identify BKCa and to study their modulation by bFGF in cultured endothelial cells of human umbilical cord veins (HUVEC). Cell counts of HUVEC were carried out on different days to analyze bFGF-induced cell proliferation and its influence by the specific BKCa blocker iberiotoxin (IBX). Using single-channel recordings, we found characteristic BKCa with a single-channel slope conductance of 170.3 +/- 2.1 pS (n = 7), half-maximal activation at internal pCa = 5.7 (n = 5; test potential: 80 mV), and dose-dependent block by IBX (25-100 nmol/l). In cell-attached patches bFGF (50 ng/ml) caused a significant increase in the open-state probability (NPo) after 6 min at test potentials of 80 and 100 mV (n = 28; p < 0.001), respectively, which lasted up to 30 min. After preincubation with pertussis toxin (100 ng/ml; 4 h) bFGF superfusion did not cause a significant increase in BKCa activity until 25 min had passed (n = 20; p < 0.01). Addition of 100 nmol/l IBX to the pipette solution caused a total block of BKCa within 2 min in cell-attached patches, whereas bFGF (50 ng/ml) was not able to activate BKCa. When incubated with IBX (25-100 nmol/l) every 2 days, bFGF-induced proliferation of HUVEC was significantly decreased by 50 (-41%) and 100 nmol/l (-50%) IBX (n = 5; p < 0.001) after 7 days. We conclude that activation of BKCa by bFGF may play an important role in bFGF-induced proliferation of human endothelial cells and thus might be important in the process of angiogenesis and vascular remodelling.

Calcium↗