Biomedical subjects

W W Meyer

Publications and source records attributed to W W Meyer.

At least 37 records · Page 2Linked to original sources

PubMed1980

Branching coefficient ("area ratio") of the human aortic bifurcation determined in distended specimens.

Branching coefficient or "area ratio" is the ratio of the sum of the cross-sectional areas of the daughter vessels of a bifurcation to that of the parent stem. The value of area ratio is important for the assessment of flow patterns in the bifurcation and, consequently, of its functional load. In this series of cases, the area ratio was determined in aortic bifurcations of 19 young persons who died suddenly. The specimens were distended during fixation. The area ratio found in this study (1.18 +/- 0.6 SE) corresponded to the optimal value (1.15) predicted on a theoretical basis for an equibifurcation. Our ratio demonstrates an increase of 1.18 in size of the vascular bed of the human aortic bifurcation. We found a significant difference between the aortic circumference measured at the level of the divider compared with the circumference 2-2.5 cm above the bifurcation. The precise level of measurement is therefore critical for a correct determination of the area ratio of the aortic bifurcation and may explain varying values reported in the literature. Deviation from optimal value, e.g. with age, may be accompanied by increased mechanical stress and could favor the prominent involvement of aortic bifurcation by atherosclerotic lesions in man.

Adolescent↗

PubMed1978

Structure and closure mechanism of the human umbilical artery.

The structure of the fully-patent umbical artery and rearrangement of its structural elements with postnatal closure were examined 10 centimeter long umbilical cord segments which were double-clamped at different time intervals after delivery. The fully-patent umbilical artery consists of two main layers: an outer layer of circularly arrange smooth muscle cells and an inner layer which shows rather irregularly and loosely arranged cells embedded in abundant metachromatic ground substance. No predominantly longitudinal arrangements of cells and fibers reported by earlier investigators could be identified in the inner layer. Closure of the umbilical arteries is initiated by numerous localized contractions which are mainly formed by muscle cells of the outer circular layer. Ultimate closure of larger segments of the umbilical arteries is also mainly produced by contractions of the outer layer. In contrast, the inner layer (which is rich in ground substance) seems to serve mainly as a plastic tissue which can easily be shifted in an axial direction and then folded into the narrowing lumen to complete closure. Electron microscopy reveals that the cells of this layer represent rather poorly differentiated smooth muscle cells which contain only a few tiny myofilaments and can therefore hardly contribute actively to the process of closure.

Cell Differentiation↗

PubMed1977

Aneurysms of the coronary arteries in infants and children. A review, and report of six cases.

In recent years large numbers of the so-called "mucocutaneous lymph node syndrome" or "Kawasaki's disease" have been described by Japanese workers, but instances of this disorder are only now being reported as isolated cases by European or North American physicians. The disease has, therefore, been considered to be a new entity. One of its most striking features is the development of aneurysms of the coronary arteries in infants or children, which may lead to sudden death. Aneurysms of the coronary arteries in childhood are rare, and hence it was considered relevant to report six such cases, and to examine their possible relationship to Kawasaki's disease. The pathological changes underlying the latter disorder are not well known; they are considered to be indistinguishable from infantile polyarteritis nodosa. A diagnosis of polyarteritis nodosa was also thought to be most likely to apply in the cases presented here, particularly in view of the frequency with which aneurysms of the coronary arteries have been found in this disorder. In the absence of valid pathological distinctions between Kawasaki's disease and infantile polyarteritis nodosa, the question arises whether these entities are, in fact, different, and whether Kawasaki's disease is the new entity it is assumed to be.

Age Factors↗

PubMed1977

The mode of calcification in atherosclerotic lesions.

In serveral arterial provinces, atherosclerosis and atherosclerotic calcifications are preceded by primary calcifications which develop in a seemingly unchanged arterial wall and often show regular gross patterns. In contrast, secondary calcifications which appear in the atherosclerotic lesions are irregularly distributed along the thickened atherosclerotic intima. At the predilection sites of atherosclerotic lesions, pronounced primary calcifications often precede the fatty streaking representing an independent pathological process. The deformation of the arterial wall resulting from calcific plaques may favor the activation of intimal mesenchyme and contribute to increased accumulation of lipid above and around calcific deposits. The exact nature of structural and biochemical changes which precede and result in primary and secondary arterial calcification still remains obscure.

Arteries↗

PubMed1976

[Primary generalization in alveolar rhabdomyosarkom (author's transl)].

Rhabdomyosarcomas are surpassed in frequency only by neuroblastomas and Wilms' tumors in pediatric oncology. An unusual variant is the primarily generalized alveolar rhabdomyosarcoma. Reviewing a case history, diagnostic, differential diagnostic and therapeutic problems are discussed. Cure appears to be unobtainable at the present time; nevertheless an aggressive approach by modern therapy seems justified as prolonged symptomfree intervals are possible without considerable side effects.

Autopsy↗

PubMed1974