Muscarinic receptor binding sites of the M4 subtype in porcine lung parenchyma.

Muscarinic acetylcholine receptors regulate distal airway resistance and secretion. The subtype expressed in the lung in different species remains uncertain. It has recently become possible to identify the M4 subtype by careful comparison of antagonist affinities. We characterized the binding of [3H]quinuclidinyl benzilate ([3H]QNB) to muscarinic receptors in cell membranes from lung parenchyma of 2-8 week old pigs in comparison to cloned human M3 and M4 receptors expressed in COS cells, to M2 in rat atria and to M4 in bovine adrenal medulla. In porcine lung, [3H]QNB bound with high affinity (Kd = 95 +/- 9 pM) to a single homogeneous population of muscarinic receptor sites (Bmax = 340 +/- 10 fmol/mg protein). Competition studies showed that the affinity (expressed as pKi) of 3 selective blockers was in close agreement between pig lung and cloned human m4 (r = 0.996). A series of 10 blockers showed affinities closely matching reported values for M4 receptors of the adrenal medulla (r = 0.965). Conversely, affinity values in porcine lung differed significantly (P < 0.05, t-test) from those determined in parallel with either human cloned M3 or with rat atria expressing the M2 subtype. We conclude that pig lung muscarinic receptor binding sites most closely resemble the M4 subtype, in contrast to the M3 subtype typical of large airways in this species.

[Congenital deficiency of fibrin stabilizing factor [factor XIII)]. / Le déficit congénital en facteur stabilisant de la fibrine ou facteur XIII.

The authors report a new case of congenital deficiency of fibrin stabilizing factor. The defect is transmitted as an autosomal recessive trait. The earliest symptom is umbilical bleeding when the cord separates. The diagnosis is confirmed by the rapid dispersion of the clot in urea 5 M or monochloroacetic acid.

Contraception and abortion in Cuba.

PIP: The main aspects of birth control in Cuba are scientific and medico-social. The scientific approach to abortion includes 19 maternal, 4 psychiatric, and 3 fetal indications for abortion. The 5 techniques used are curettage, vacuum aspiration, intra-ovular methods after 14 weeks, Krause method, and hysterotomy. Medico-social aspects of abortion include all legislation on abortion, official standards not supported by legislation and statistical data. Contraceptives are indicated for couples who wish to plan their families, in every case of induced non-septic abortion, after repeated abortions until investigation is completed and the causes determined and in selected cases after cesarean section. While the ideal contraceptive does not exist the author considers the diaphraghm least harmful to the woman's genital organs and the most comfortable.^ieng