Untersuchungen über die Permeabilität lebender Membranen. VIII

Zusammenfassung In vorliegender Arbeit konnten wir die Anwendbarkeit unserer in der vorigen Mitteilung für tensioaktive Gifte und antekritische Vergiftungssymptome abgeleiteten Vergiftungsgleichungen auf die Ergebnisse unserer mit Saponin an Atherina hepsetus L. ausgeführten Vergiftungsversuche (vgl. III. Mitteilung) bestätigen.Mit 1 Textabbildung.VII. Mitteilung: Naunyn-Schmiedebergs Arch.191, 628 (1939).     

PLACENTAL CALCIUM PUMP: CLINICAL-BASED EVIDENCE

Placenta can be considered as a pump of calcium necessary for the normal development of the fetus. We believe that the location of this pump is in the placental basement membrane. The calcification of this membrane has been described only in cases of in utero fetal death. In this study we describe for the first time a case of placental calcification in a living fetus. The fetus of a normal 21-year-old pregnant woman showed heart abnormalities but the genetic analysis showed a normal male karyotype. The histology of the placenta demonstrated multiple intravillous linear and granular calcific incrustations The hemtoxylin/eosin stain of the sections revealed basement membrane calcific incrustations and intravillous calcium deposits. We postulate that the fetal circulation in the villi was impaired and the calcium that reached the villi from the mother was deposited at this level.     

Cellular kinetics of prednimustine versus chlorambucil plus prednisolone in vitro

Summary Intracellular concentrations of prednimustine (PM), chlorambucil (CLB), phenylacetic acid mustard (PAAM) and prednisolone (P) were measured in different experimental tumor cell lines that had been incubated with either PM or CLB+P. For intracellular analytical determination, we modified a high-pressure liquid chromatographic method for the detection of these substances in plasma. Intact PM could be detected in the intracellular compartment of the incubated tumor cells. PM-incubated cells from PM-injected rats exhibited a higher intracellular concentration-time integral (PAAM) and longer concentration-time profiles for drugs with alkylating capacity than did cells exposed to the CLB+P mixture or to CLB. PAAM was not detectable after incubation of cells with PM, whereas in CLB-incubated cells the AUC of PAAM exceeded that of the parent drug CLB. Our in vitro results therefore favour the concept of a facilitated intracellular uptake and an increased antiproliferative effect for PM versus CLB and CLB+P.Dedicated to Prof. Dr. H. J. Dengler on the occasion of his 65th birthday. This study was supported by the Ministry of Science and Research of Nordrhein-Westfalen     

Fibronectin--a plasmin-sensitive glycoprotein of the transit zone: protection by aprotinin

Intravascular and extravascular fibronectin represents an essential "early information-transmitting" molecule of the transit zone. It appears to play a part especially in the flow of information provoked by sympathetic reactions (every form of stress), which is associated with a rise in plasmin levels. The rapid proteolytic cleavage of fibronectin by plasmin alters the composition of the ground substance, hence its informational contents. This is transmitted to the glycocalyx of affected cells, provoking a reaction typical of those particular cells. When a stress goes beyond the physiological margin of tolerance, an excessive break-down of fibronectin quickly ensues so that the transit zone will transmit faulty information. It has been demonstrated on human and animal tissue that initial use of the potent plasmin inhibitor aprotinin (Trasylol) can provide a selective protection of fibronectin and, consequently, of the transit zone. Clinical results obtained in patients with multiple injuries corroborate this observation.     

Induction of vascular haemostasis by Nd:YAG laser light in melanin-rich and melanin-free tissue

Haemostasis was effected in vessels of melanin-rich (MR: choroid) and melanin-free (MF: mesentery) rabbit tissue irradiated with a cw-Nd: YAG laser. The following parameters were employed: - pulse duration: 200 ms (MR) and 100ms (MF); focal spot diameter: 200 m (MR) and 80 m (MF); pulse energies: 100–250 mJ (MR) and 0.5-1J (MF); irradiances: 1.6–4.0kWcm^–2 (MR) and 1–2 × 10²kWcm² (MF). In melanin-rich tissue, laser energy is absorbed principally by melanin granules contained within the stromal melanocytes. The heat generated in these structures radiates into the surrounding tissue where it is dissipated. The damage thus incurred by the endothelium of blood vessels encompassed within this field triggers the haemostatic mechanism whereby blood flow is arrested. This effect is realized by the formation of an occluding plug of platelets, which is stabilized by the deposition of fibrin, particularly in capillaries, and to a lesser degree in larger vessels of the vascular lamina. In melanin-free tissue, haemoglobin serves as the primary site of energy absorption, which is thus shifted from the stroma to the vessel lumen. Irradiation of vessels in such tissue leads to thermocoagulation of plasma proteins and consequent stasis of blood flow.     

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