The origin of the instantaneous elasticity in single frog muscle fibres.

High-speed cinematographic recordings of single tetanized muscle fibres during a quick decrease in length revealed that the shortening was mostly localized at the fibre segment nearest the released end of the fibre, indicating that the instantaneous elasticity may not originate from the elasticity of the cross-bridges.     

The late-twentieth century resolution of a mid-nineteenth century dilemma generated by the eighteenth-century experiments of Ernst Chladni on the dynamics of rods

Communicated by C. Truesdell     

The origin of the series elastic component in single crayfish muscle fibres.

High-speed cinematographic studies on the length changes of single tetanized crayfish muscle fibres during a step decrease in length revealed a farily uniform distribution of a highly compliant series elastic component along the fibre length, suggesting that it mainly originates from some structures in each sarcomere other than the cross-bridges.     

Characterization of the third component of pig complement and its utilization in a C3b receptor study

Summary The third component of the pig complement system (C3) was isolated in hemolytically active form and characterized. The C3 component is a -globulin with the molecular weight of 191,000 and is composed of 2 non-identical polypeptide chains of M_t 112,000 and 74,000. The isolated C3 can be used for the detection of the C3b receptor on the membranes of heterologous peritoneal macrophages.     

The role of the subependymal plate in the origin of gliomas induced by ethylnitrosourea in the rat brain

Summary The fine structure of early cell proliferations induced transplacentally by ethylnitrosourea in the rat brain reveals that the cells show features of the undifferentiated cells of the subependymal plate: high nuclear-cytoplasmic ratio, scarcity of cell organelles and dominance of free over membrane-bound ribosomes. These findings suggest that most, if not all, gliomas induced by ethylnitrosourea originate from these primitive cells.Acknowledgments. I thank D. J. Cox and G. J. Pilkington for their skilful technical assistance.     

The Hill equation and the origin of quantitative pharmacology

This review addresses the 100-year-old Hill equation (published in January 22, 1910), the first formula relating the result of a reversible association (e.g., concentration of a complex, magnitude of an effect) to the variable concentration of one of the associating substances (the other being present in a constant and relatively low concentration). In addition, the Hill equation was the first (and is the simplest) quantitative receptor model in pharmacology. Although the Hill equation is an empirical receptor model (its parameters have only physico-chemical meaning for a simple ligand binding reaction), it requires only minor a priori knowledge about the mechanism of action for the investigated agonist to reliably fit concentration-response curve data and to yield useful results (in contrast to most of the advanced receptor models). Thus, the Hill equation has remained an important tool for physiological and pharmacological investigations including drug discovery, moreover it serves as a theoretical basis for the development of new pharmacological models.     

On the origin of the antiheparin activity of serum. The effect of reserpin

Zusammenfassung Es wurde gezeigt, dass Zusatz von Reserpin zum Blut die Antiheparinaktivität im Serum deutlich steigert. Da Reserpin zugleich die Thrombocyten beeinflusst, wird vermutet, dass diese für die Antiheparinaktivität verantwortlich sind.     

The micro-focal x-ray unit and its application to bio-medical research.

The micro-focal X-ray unit is a modified Cosslett and Nixon X-ray microscope of greater operational stability and flexibility. Its combination with a closed circuit television system provides a quick method of obtaining a point source of X-rays to examine the detailed structure of organs and biological specimens.     

The origin of the action potential in frog stomach muscle and heart

Zusammenfassung Das Aktionspotential von Herz- und Magenmuskulatur des Frosches scheint nicht vom Einund Ausstoss der Ionen, sondern vom elektronischen Aufbau der Zellmembran abhängig zu sein.     

The consequences of the discovery by W. C. Röntgen for present-day medical physics and radiation protection

When the German physicist W. C. Röntgen discovered X-rays, which were named after him, he introduced a new development in medicine and biology: together with the discoveries of A. H. Becquerel and M. Curie, radiology with its diagnostic and therapeutic methods was made possible. The medical physicist has an important task to fulfill in modern radiotherapy, nuclear medicine and radiodiagnostics. The longtime interdisciplinary collaboration has won the international recognition of medical physics as a scientific discipline, a health care profession and a university subject. Several incidents, including contemporary ones, show that the efforts made towards radiation protection must remain an important domain of the specialist.