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Nel corso del presente esperimento abbiamo studiato gli effetti di un’unica somministrazione intraperitoneale di particelle di carbone colloidale, vale a dire di un agente ingolfante i macrofagi, sul quadro istologico e sulla reattivita immunitaria primaria ai G.R.M., nel topo di ceppo BALB/c. Il carbone colloidale e stato iniettato a diversi intervalli di tempo prima, contemporaneamente o dopo l’immunizzazione. I risultati indicano che il trattamento con carbone deprime la risposta immunitaria primaria solo se questo e stato somministrato a brevi intervalli prima dell’antigene. Di conseguenza i macrofagi sembrano giocare un ruolo molto importante negli eventi cellulari associati alla risposta immunitaria primaria ai G.R.M. Appare anche evidente dalle riportate osservazioni che l’interazione macrofago-antigene avviene effettivamente e precede l’interazione fra T-linfocita ed antigene. Inoltre si ritiene di poter suggerire che i macrofagi peritoneali costituiscano un terzo tipo cellulare necessario per l’instaurarsi della risposta immunitaria primaria ad alcuni antigeni particolati somministrati per via peritoneale.

Tritiated thymidine radioautography was employed to study the effect of epinephrine on cellular proliferation in the aorta and pulmonary artery of rabbits with cholesterol atherosclerosis. Rabbits fed cholesterol for 90 days were given epinephrine intravenously in a single large dose or in multiple low daily doses. Labeled cell counts in animals killed at intervals ranging from one to twelve days after the start of treatment showed that both treatments, as compared with controls, increase the deoxyribonucleic acid synthesis both in intimal plaques and in the media. This effect was particularly evident in the animals treated with low daily doses which, otherwise, in light and electron microscopy studies showed less marked structural changes of the medial coat. No definite relationship was found to exist between increased rate of DNA synthesis and serum cholesterol levels. It is suggested that the increased DNA synthesis induced in the atherosclerotic vessels by epinephrine is not merely a consequence of the structural damage, but should also be regarded as a response of the arterial wall to functional and/or metabolic stimuli that are as yet undetermined. On the other hand it is concluded that the contributing or enhancing effect of epinephrine on cholesterol atherogenesis might be due, at least partly, to the increased mitotic rate into the arterial wall.

DeBoer and Broekhoff have proposed that inflections occur in adsorption isotherms at one-third of a monolayer if the adsorbent is homogeneous and the adsorbate does not undergo two-dimensional condensation. This concept has been applied to data for furan, thiophene, and 1,4-cyclohexadiene adsorbed on Graphon carbon black. The method needs only sample weight and thermocouple readings from which to compute the inflection corresponding to one-third of a monolayer. It is shown that this method can agree with the Brunauer-Emmett-Teller method for determining monolayer points only if the BET constant c has a value near 10.

Sequential fine structural changes were assessed in the aortic media of rabbits shortly after the intravenous injection of a massive single dose of adrenaline. Slight changes first appeared at 1 hour and by 6 hours marked changes were present which included accumulation of Alcian-stainable material in the intercellular spaces and alterations in mitochondria of smooth muscle cells. The mitochondria were swollen and showed decreased matrix density together with the presence of electron dense microcrystalline inclusions. Electron diffraction studies showed that these inclusions were composed by apatite-like crystals. The mechanism(s) involved and the possible pathological role of the mitochondrial calcification are discussed.