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Biomedical subjects

P Wiederkehr

Publications and source records attributed to P Wiederkehr.

11 recordsLinked to original sources
PubMed1988

[Computed tomographic diagnosis of dissecting aneurysm of the aorta].

Twenty-four patients with dissecting aortic aneurysms have been examined by CT and possible causes of mistaken diagnosis are discussed. Failure to diagnose a dissection by CT may be due to atypical localisation and thrombosis of the aortic dissection; dissections of small volume, particularly in the ascending aorta; failure to demonstrate an intimal flap and inadequate contrast enhancement. A false positive diagnosis may be due to fibrotic, inflammatory or neoplastic periaortic changes, aneurysm of the sinus of Valsalva, or artifacts.

Aged↗
PubMed1986

Androgen and estrogen effect on guinea pig seminal vesicle muscle: a combined stereological and biochemical study.

A combined electron microscopic stereological and biochemical study of the smooth muscle cells of guinea pig seminal vesicles was performed in intact, castrated, castrated and dihydrotestosterone- or estradiol-treated adult animals. Castration led to cell atrophy as determined stereologically by a decreased single cell volume and biochemically by no change in DNA content coupled with an increase in the DNA concentration. Treatment of castrates with dihydrotestosterone restored both the stereological and biochemical parameters of the cell size to slightly supranormal levels. The estrogen-induced increase in muscle weight and DNA content appeared to be due only to hyperplasia of muscle cells and not to a proliferation of fibroblasts or to infiltration by inflammatory cells. In all treatment groups, including the estrogen-treated castrates, more than 95% of the cells in the tissue were smooth muscle cells, and there was no evidence that polyploidy contributed to changes in DNA levels. In addition, in the estrogen-treated muscles, DNA concentration remained high, and the stereologically determined cell size remained low. Therefore, both morphological and biochemical evidence indicate that androgen induces hypertrophy, whereas estrogen induces hyperplasia of muscle cells. The correction of stereological and biochemical data validates the application of stereological cell size determination for smooth muscle cells in organs that hardly can be separated into stromal and epithelial components; eg, the prostate.

Animals↗
PubMed1985

[Tumor of the hand, free flap and irradiation. Anatomo-pathologic study apropos of 1 case].

After excision of a recurrent squamous cell carcinoma of the ulnar border of the right hand and forearm, we covered the defect with a free scapular flap. The flap and the tumor site were irradiated post-operatively (4 000 Rad). In spite of the irradiation the tumor recurred and we performed a below elbow amputation. Angiography of the amputated part showed the patency of all the flap vessels. However the histological features confirming the effect of the radiotherapy, particularly on the vessels, showed intimal proliferation and signs of necrosis of the media. We concluded that despite these findings the viability of free flaps is not jeopardized by radiotherapy, as long as their size is not reduced by more than 30% as compared to normal, and as long as the vascular anastomoses are done outside of the field of irradiation.

Aged↗
PubMed1982

[Scintigraphic study of reflex algodystrophy].

Isotope investigation of reflex sympathetic dystrophy is not limited to an evaluation of bony up-take, it also includes examination of the early dynamic scintigraphy of the vessels. The late views of bone scans reflect, above all, the bone's affinity for phosphate complexes i.e. the degree of osteoblast activity. Generally, dystrophies, independent of their site, show increased locoregional uptake, often quite intense, which appears early in the course of the disease. This supports histopathological findings. There are several advantages in using the bone scan in the investigation of reflex dystrophy: early diagnosis before the development of radiological signs, precise evaluation of the local extension of the dystrophic process and detection of the incidence of multifocal forms, follow-up of the course of the disease, definition of new clinical forms: patchy algodystrophy partial, decalcifying dystrophy, sub-radiological dystrophy, the aetiology in certain sites (especially the hip). Early dynamic scans that dystrophy is accompanied by an increase in the vascular compartment and decreased circulatory flow, a sign of the local stage of the disease. There is also an increase of the interstitial compartment, greater than that of the vascular compartment, explaining the presence of edema. The pathophysiological information gained from dynamic studies is matched by the therapeutic information: evaluation, or even prediction, of the effect of a given drug (cortisone, calcitonin).

Bone and Bones↗
PubMedDate not supplied

[Stress fractures of the pelvis].

Stress fractures of the pelvic ring should be suspected everytime a patient complains of hip pain. These stress fractures are more likely to occur in elderly, obesity, rheumatoid arthritis, osteoarthritis of the hip and after total hip replacement. A bone scan should be performed for early diagnosis, for roentgenolographic evidence of stress fracture often one ago two or three weeks behind the onset of symptoms.

Adult↗