Isoproterenol evokes extracellular Ca2+ spikes due to secretory events in salivary gland cells

Secretory cells should in principle export substantial amounts of calcium via exocytosis since Ca2+ is sequestered in secretory granules. Based on a new technique for measurements of the extracellular calcium concentration in the vicinity of the cell membrane and on the droplet technique, we have monitored the rate of calcium extrusion from salivary gland acinar cells. Isoproterenol (ISP), a beta-adrenergic agonist and powerful secretogogue, evoked no change in the cytosolic free Ca2+ concentration ([Ca2+]i) but induced vigorous extracellular Ca2+ concentration ([Ca2+]i) spiking. The absence of [Ca2+]i elevation and the pulsatile nature of the changes in [Ca2+]i indicate that these spikes are most likely due to calcium release from secretory granules. The cholinergic agonist acetylcholine (ACh), which induces moderate secretion, evoked a marked rise in [Ca2+]i and a smooth rise in [Ca2+]i, most likely induced by plasma membrane calcium pumps, on which shortlasting [Ca2+]i spikes were superimposed. The rate of ISP-induced calcium efflux was very substantial. The calculated calcium loss during the first 100 s of supramaximal stimulation corresponded to a reduction of the total cellular calcium concentration of approximately 0.4 mM. We conclude that in salivary glands, calcium release via exocytosis is one of the main mechanisms extruding calcium from cells to the extracellular milieu.     

Prophylactic effect of enteral feeding preparations during the chemotherapy of oncology patients

Altogether 124 patients were followed up for disseminated breast cancer (82) and hematosarcoma (42). The patients were divided into two groups: the main group was given 500 ml of 20% protein or low-lactose enteral feeding in addition to the hospital diet; the control group received only the hospital diet. Chemotherapy lasted 3 weeks. The patients on chemotherapy received enteral feeding every day throughout the entire treatment period. In the course of treatment, the patients were examined for blood characteristics, size of the tumor and affected lymph nodes, body weight, major metabolism, protein metabolism, vitamin metabolism, osmotic and peroxide resistance of red cells, and liver function. The research program covered more than 150 characteristics. The data obtained were processed by computer. It has been disclosed that inclusion of protein and low-lactose enteral feeding into the diet of cancer patients improves the alimentary status, decreases the leukopenia and thrombocytopenia incidence. It is advisable that specialized milk concentrates (enteral feeding) should be included into the diet of cancer patients as a necessary component of a complex of therapeutic measures used during chemotherapy.     

Synthesis of phosphorus-, zinc-, and chlorine-containing poly(ethylene terephthalate)

Phosphorus-, zinc-, and chlorine-containing oligomer was used as a comonomer including ionic bonds in its molecules in the synthesis of poly(ethylene terephthalate). Phosphorus-, zinc-, and chlorine-containing poly(ethylene terephthalate) including ionic bonds in its main polymer chain was synthesized. With a content of 0.6% P and 1.25% Zn and 0.1% Cl, the resin has the following characteristics: η_rel = 1.407; COOH 39.90 mg equiv KOH/g 10^?6; and mp 255.8°C. The modifier acts as a thermostabilizer. © 1993 John Wiley & Sons, Inc.