[Modification of chromatin condensation in cultured macrophages during induction of cell division by an inflammatory exudate]

The determination of chromatin condensation in rat peritoneal macrophages in culture showed a predominance of heterochromatin with low transcriptory activity. After induction of division in rat peritoneal macrophages in culture by an acute inflammatory exudate, a decrease of heterochromatin and an increase of euchromatin were observed. This result brings further evidence to support previous observations according to which this type of exudate shows mitogenic properties.

Inhibitory action of human serum on the isoprenaline-induced chronotropic effect in cultured rat heart cells. Influence of sex and pregnancy

Cultures of beating rat myocardial cells brought into contact with various human sera during 24 hours were infused with isoprenaline. The isoprenaline-induced positive chronotropic effect (IIPCE) was not found with all sera. IIPCE was present in all the male sera, but was absent in the cases of clinically beta-blocked pindolol treated men. IIPCE was present only in about 50% of the female sera, menopaused or not. IIPCE was absent in 95% of the sera of pregnant women in the late phase of pregnancy. This suggests the presence in female sera, especially during pregnancy, of a circulating factor capable of "in vitro" inhibition of isoprenaline-induced positive chronotropic effect.

Differences between elevations of plasma and serum potassium in pentobarbital-narcotized cats during asphyxia

During acute asphyxia in pentobarbital-narcotized cats, the elevation in plasma potassium level was parallel to that of PCO2. From the time when PO2 reached its minimum, the elevation in serum potassium was higher than that of plasma potassium. The increase of the difference between serum and plasma potassium values seems therefore to be more related to hypoxia than hypercapnia; it could be due to membrane alteration of blood cells.

[The effect of mepyramine and 48/80 on the histamine content of pleural exudates in the rat]

The influence of pretreatment with the antihistaminic, mepyramine, or with the histamine liberator 48/80 was studied on the volume and the histamine content of pleural exudates induced in rats by intrapleural injection of turpentine, silver nitrate or carrageenan. The fluorometric determination of histamine was performed in the exudates collected at different times after injection of the irritant. In control animals the histamine levels were different from those previously found by the authors using biological assays. In rats pretreated with mepyramine or compound 48/80, the effects observed varied according to the nature of the irritant used to induce pleurisy.

Induction of DNA synthesis in rat peritoneal macrophages in culture by a pleural inflammatory exudate

Peritoneal macrophages in culture are blocked in the G0 phase of the cell cycle, but retain many of their functional characteristics such as phagocytic ability. Peritoneal macrophages have been thought to be a terminal cell type. It has been investigated whether such properties could be modified by a substance released in acute inflammatory exudates. For this purpose a pleural exudate obtained from rats injected with dextran (40,000) 4 hours before, was centrifuged to eliminate cells, sterilized by filtration on Millipore filter 0.22 mum and diluted 50% with 199 medium culture. This medium was used to treat normal and activated peritoneal macrophages in culture. The effects were observed 24, 48, 72, 96 hours after the beginning of treatment. An enhancement of spreading and capacity of phagocytosis was observed 24 hours after the beginning of treatment. After 48 hours, the number of cells incorporating tritiated thymidine increased and became highest 4 days later. These phenomena were also obtained with pleural exudate of inbred rats (Lewis, Wag) treating macrophages of the same strain and with rat pleural exudate treating mouse macrophages. No effects were observed with dextran alone. The chemical nature of the stimulatory factor remains to be elucidated.

Comparison of the biological effects in rat of high doses of two 4-amino-7-chloroquinoline derivatives: chloroquine and glafenine

When given orally in elevated but nonlethal doses (150 to 450 mg/kg, on 2 consecutive days), glafenine induces in rats (body weight 100 g) a transient nephritis with an increase in blood urea, hypertrophy of adrenals, and some changes in the serum proteinogram. These effects do not appear to be due to the 4-amino-7-chloroquinoline structure from which glafenine is derived, as they are not observed with the structural analogue chloroquine given at equimolar doses under the same conditions. Further, they do not appear to be due to glycerol, the by-product of metabolic glafenine hydrolysis. The responsible molecule appears to be either glafenine itself or its acid metabolite 4-(0-carboxyphenylamino) 7-chloroquinoline.

[Changes in transmitter release at frog neuromuscular junction induced by 4-aminopyridine]

4-aminopyridine (4-AP) at micromolar concentrations, increases the end-plate potential amplitude in curarized preparations and the mean quantal content in every preparation tested, but the spontaneous release is not modified by 4-AP. These results can explain the anticurare activity observed in the wole animal or in vitro. 4-AP prolongs the falling phase of the muscle action potential without change in the muscle membrane potential.

[Chemistry and pharmacology of glucocorticosteroids]

The glucocorticosteroids are derived chemically from androsterone or pregnane. Their natural models are cortisone and cortisol (or hydrocortisone), characterised by the presence of oxygen or an oxydryle group at 11, of a --CO -- CH2OH group in the 17 position and of an-OH group in the 17 position. Their anti-inflammatory power dominate their pharmacodynamics: it goes hand in hand with their power to increase gluconeogenesis. They have an immunodepressant effect whose power seems to be proportional the their anti-inflammatory action. The use of hydrocortisone in the treatment of shock remains empirical. The mechanism of their anti-allergic effect remains debated. Glucocorticosteroids disturb lipid and protein metabolism, water and electrolyte balance, the central nervous system, and gastric secretion; they inhibit the secretion of ACTH. Their pharmaceutical forms are numerous: they are adapted to the oral route and to the parenteral routes (i.m., i.v., i.r., intra-articular) and to external use (cutaneous and mucosal applications).

[Electrophysiological analysis of the effects of 4-amino-pyridine in the isolated heart ventricle of the guniea pig]

The effects of 4-aminopyridine (4-AP) on guinea pig myocardial ventricular isolated strips were studied by means of intracellular microelectrodes. 4-AP increased the maximal depolarization velocity and decreased the effects of quinidine. In contrast to adrenaline, 4-AP antagonized the effects of MnCl1, but was ineffective against the alterations induced by a sodium poor solution. These findings support the suggestion that 4-AP modifies the electrophysiological membrane properties probably by increasing the Na+ inward current.