Possible interaction of platelets and adrenaline in the early phase of myocardial infarction.

It is known that in most cases of transmural acute myocardial infarction a platelet clot originates within a coronary artery. In acute myocardial infarction patients increased levels of the plasma catecholamines adrenaline and noradrenaline as well as the platelet release proteins platelet factor 4 and beta-thromboglobulin have been reported. In this study, significantly higher values were found of platelet factor 4 (P less than 0.

[Separation of a Beall Surgitool prosthesis disk 15 years after mitral valve replacement].

The case of a 46-year-old woman who survived disc embolization of a Beall Surgitool prothesis for 10 days is described. The patient presented to another hospital 15 years after implantation of a mitral valve prothesis with acute severe heart failure refractory to medical therapy. Ten days later she was referred for cardiological investigation and a missing mitral valve disc was diagnosed by echocardiography and right heart catheterization.

Inhibition of the uptake of nucleosides in cultured Harding-Passey melanoma cells by diflubenzuron.

Diflubenzuron (DFB) significantly inhibited the uptake of uridine, adenosine, and cytidine but not thymidine, in cultured Harding-Passey melanoma cells. Inhibition of nucleoside uptake was rapid (i.e.

[Influence of x-rays and quinacrine (atebrine) or chloroquine (resochine)--alone or in combination--on growth and melanin formation of Harding-Passey melanoma cells in monolayer culture].

Harding-Passey melanoma cells in monolayer culture (HPM-73 line) were treated during exponential growth phase with single doses of X-rays (85 kV) from 2 up to 16 Gy (200 to 1600 rd). While 2 or 4 Gy resulted in a growth retardation (up to 2 days) followed by resumption of proliferation thereafter, 8 Gy, and still more pronounced 16 Gy, resulted in a significant decrease of the survival rate (till about 5 to 10% after 8 Gy). In the course of several days after 8 or 16 Gy numerous large cells--in comparison with controls--were formed, and following exposure to 8 Gy the average cellular protein content had more than doubled (and after 16 Gy more than tripled) in the course of 11 days.

Enhanced melanization of Harding-Passey mouse melanoma cells following treatment with exogenous melanosomes in monolayer culture.

Purified melanosomes isolated from subcutaneously growting Harding-Passey melanomas of NMRI-mice were labeled either in vitro with [14C]tyrosine or [14C]DOPA in the melanin portion, or in vivo in the melanin and protein portion following i. p. injection of [14C]tyrosine.

The effect of atebrine and an acridine analog (BCMA) on the coenzyme fluorescence spectra of cultured melanoma and Ehrlich ascites (EL2) cells.

Coenzyme fluorescence spectra of single living cells are due to free pyridine nucleotides (folded configuration), bound pyridine nucleotides (unfolded configuration) and a third component, possibly a mixture or flavins. Such spectra can be used to recognize possible differences in coenzyme composition between cell lines or changes of metabolic pathways due to chemicals acting at levels below or above cytotoxicity, by high resolution spectrofluorometry. A study of spectra recorded from cultured Ehrlich ascites (EL2), and Harding Passey melanoma cells (HPM-67 and HPM-73 line) grown under comparable conditions, shows that free NAD(P)H predominates in HPM-67 and EL2, while this coenzyme is bound in HPM-73.

Uptake of melanosomes and increased melanin formation by cultured melanoma cells after treatment with isolated melanosomes.

Melanosomes isolated from a subcutaneous Harding-Passey mouse melanoma and purified by density gradient centrifugation were labelled in vitro with 14C-tyrosine or 3H-dihydroxyphenylalanine in the melanin portion. Incubation of monolayer cultures of Harding-Passey melanoma cells during exponential growth phase (wherin cells contained relatively few melanosomes) with isolated and labelled melanosomes during a time-period of up to 3 days resulted in rapid cellular uptake of label (reaching a saturation level after about half a day). Following a lag period of several hours, the melanin content rose near-linearly in the course of 3 days.

Stimulation of tyrosinase activity and melanin formation of cultured melanoma cells by serum deprivation alone or in combination with dibutyryl cyclic AMP and theophylline.

Serum removal from the media of serial monolayer cultures of the Harding-Passey melanoma during an incubation period of 3 days resulted in an exponentially declining DNA synthesis rate (measured by the incorporation of [14C]thymidine) and in an inhibition of cell proliferation. Protein synthesis, as measured by the incorporation of radioactive leucine, was less affected than DNA synthesis. Incubation in serum-free culture medium resulted in significant rises of tyrosinase activity and cellular melanin content.