Identification and localization of a novel cathepsin S-like proteinase in guinea pig spermatozoa.

Guinea pig spermatozoa were found to contain a novel cysteine proteinase that most closely resembled lysosomal cathepsin S. The responsible enzyme was shown to have an acrosomal localization. Like the cathepsin S of lymphocyte-rich tissues, e.g., lymph nodes and spleen, the spermatozoal enzyme digested protein substrates such as hemoglobin and Azocoll optimally at about pH 3.5 in the presence of pepstatin. No appreciable action was manifested in the range of pH 5-6 on protein substrates nor on the 7-(4-methyl)coumarylamide (NMec) derivatives of peptides commonly employed for the fluorometric assay of cathepsins B (benzyloxycarbonyl (Z)-Arg-Arg-NMec), H (Arg-NMec), and L (Z-Phe-Arg-NMec). Like spleen cathepsin S, the sperm enzyme selectively hydrolyzed Z-Phe-Arg-NMec, but its activity was uncharacteristically limited to a pH range of 3.0-3.5, where it displayed a typical high sensitivity to sulfhydryl reagents (HgCl2, mersalyl acid, iodoacetate), leupeptin, Z-Phe-Phe-CHN2, and L-trans-epoxysuccinylleucylamido(3-methyl)butane. Gossypol (a male antifertility agent) was also inhibitory. Inhibition by the mercurial sulfhydryl reagents was completely reversible with dithiothreitol. Pepstatin, a potent inhibitor of aspartic proteinases, and serine proteinase inhibitors (phenylmethylsulfonyl fluoride, benzamidine) were ineffective. Other properties displayed by the sperm extract that were uniquely characteristic of cathepsin S included stability under alkaline conditions, and a greater rate of hydrolysis when the P2-phenylalanine of the assay substrate was replaced by two aliphatic residues, as in Z-Leu-Leu-Arg-NMec.

Anatomic pathways facilitating middle cerebral artery bypass.

Occlusion of the middle cerebral artery by thrombi is a relatively common occurrence resulting in stroke. Prompt intervention by dissolution or bypassing the thrombi could reduce the severity of the effects. Here, the anatomic pathways facilitating a bypass are explored. Four possible arteries, the two superficial temporals, left and right, and two middle meningeals, left and right, are in positions adjacent to branches of the middle cerebral arteries, the trunks of which are located in the lateral fissures of the brain. The first possibility is anastomosing a branch of the superficial temporal artery with the middle cerebral artery segment in the lateral fissure where this segment is usually clear of thrombi. The second possibility is anastomosing a branch of the middle meningeal artery with the postthrombotic segment of the middle cerebral artery. These anastomoses are to be done with donor and recipient arteries of the same side. In the unlikely event that these two possibilities are lost, it is still possible to anastomose the affected middle cerebral artery with the superficial temporal or middle meningeal artery of the opposite side using several inches of saphenous vein.

Acid-proteinase activity of rat cartilage dependent on growth hormone.

Cartilage slices from normal rats, incubated at pH 4 for 3 to 7 hours, on a gelatin-membrane substrate, digested the membrane, whereas cartilage from rats hypophysectomized for 21 days or more did not. Injection of 15 or 45 microgram of bovine growth hormone into hypophysectomized rats restored the lytic activity of the cartilage. It is concluded that an acid proteinase is present in cartilage of normal rats, that is lost after hypophysectomy, and that the enzyme is restored by injection of growth hormone.