NK(2)-receptor mediated contraction in monkey, guinea-pig and human airway smooth muscle.

Neurokinins (NK) are implicated in airway pathology. Selective NK(2)-receptor antagonists may prove therapeutic in airway disease. We studied Neurokinin A (NKA) responses of isolated, cryopreserved cynomolgus monkey, fresh guinea pig, and fresh and cryopreserved human airways. NKA contracted monkey trachea (pD(2)= 7.9), guinea-pig bronchus (pD(2)= 8.8) and human bronchus (pD(2)= 7.1). Potency rank order (pK(b)) of NK(2)-antagonists, SR 48968 and GR 159897, and a dual NK(1)/NK(2)-antagonist, MDL 103392, against NKA responses in monkey trachea, guinea pig and human bronchus, respectively, were SR 48968 (9.29 +/- 0.11, 9.15 +/- 0.10 and 9.51 +/- 0.17) > GR 159897 (8.45 +/- 0.26, 8.19 +/- 0.13 and 8.57 +/- 0. 22) > MDL 103392 (6.55 +/- 0.13, 6.97 +/- 0.14 and 7.16 +/- 0.13). CP 99994 (1 microM), a NK(1)-receptor antagonist, was inactive against NKA responses in all three species. The NK(3)-antagonist SR 142801 (1 microM) was inactive against NKA in monkey trachea and guinea-pig bronchus, but demonstrated weak antagonist activity (pK(b)= 6.97 +/- 0.03) in human bronchus. These findings demonstrate that NK(2)-receptors mediate tracheal smooth muscle contraction to NKA in cynomolgus monkey and that the pharmacological responsiveness of airway NK(2)-receptors in the three species studied is similar. Furthermore, our results suggest that cryopreservation may extend the viability of human and non-human primate airway tissue for studies of neurokinin receptor pharmacology. Studies are needed to further determine the similarity in neurokinin pharmacology between fresh and cryopreserved airway tissue.

Pharmacological characterization of histamine H3 receptors in human saphenous vein and guinea pig ileum.

Studies were performed to assess the functional activity of histamine H3 receptors on neurogenic sympathetic end organ responses in cryopreserved human saphenous vein. (R)-alpha-methylhistamine inhibited electrical field stimulation-evoked contractile responses in a dose dependent manner (pD2 = 8.20). Prazosin (1 microM) and tetrodotoxin (1 microM) blocked the electrical field stimulation-evoked contractile responses in human saphenous vein indicating a sympathetic neural origin of these contractions. The histamine H3 antagonists thioperamide (pA2 = 8.41) and clobenpropit (pA2 = 10.10) produced parallel rightward shifts in the concentration response curve to (R)-alpha-methylhistamine in human saphenous vein and guinea pig ileum (pA2 = 8.59 and 9.83, respectively). Pretreatment with (R)-alpha-methylhistamine (1 microM) did not alter contractions to exogenous norepinephrine in human saphenous vein. In addition, clonidine (pD2 = 10.28) inhibited electrical field stimulation-evoked contractile responses in human saphenous vein which were blocked by yohimbine (30 nM, pA2 = 9.92) but did not alter the (R)-alpha-methylhistamine dose response curve. These results demonstrate the presence of functional presynaptic histamine H3 heteroreceptors on cryopreserved human saphenous vein sympathetic nerves that, upon activation, attenuate electrical field stimulation-evoked contractile responses in this vessel.

Production of virus by mammalian cells tranformed by Rous sarcoma and murine sarcoma viruses.

Cultured cells of mammalian tumors induced by ribonucleic acid (RNA)-containing oncogenic viruses were examined for production of virus. The cell lines were established from tumors induced in rats and hamsters with either Rous sarcoma virus (Schmidt-Ruppin or Bryan strains) or murine sarcoma virus (Moloney strain). When culture fluids from each of the cell lines were examined for transforming activity or production of progeny virus, none of the cell lines was found to be infectious. However, electron microscopic examination of the various cell lines revealed the presence of particles in the rat cells transformed by either Rous sarcoma virus or murine sarcoma virus. These particles, morphologically similar to those associated with murine leukemias, were found both in the extracellular fluid concentrates and in whole-cell preparations. In the latter, they were seen budding from the cell membranes or lying in the intercellular spaces. No viruslike particles were seen in preparations from hamster tumors. Exposure of the rat cells to (3)H-uridine resulted in the appearance of labeled particles with densities in sucrose gradients typical of virus (1.16 g/ml.). RNA of high molecular weight was extracted from these particles, and double-labeling experiments showed that this RNA sedimented at the same rate as RNA extracted from Rous sarcoma virus. None of the hamster cell lines gave radioactive peaks in the virus density range, and no extractable high molecular weight RNA was found. These studies suggest that the murine sarcoma virus produces an infection analogous to certain "defective" strains of Rous sarcoma virus, in that particles produced by infected cells have a low efficiency of infection. The control of the host cell over the production and properties of the RNA-containing tumorigenic viruses is discussed.

Fine structure and host-virus relationship of a marine bacterium and its bacteriophage.

Valentine, Artrice F. (Georgetown University, Washington, D.C.), and George B. Chapman. Fine structure and host-virus relationship of a marine bacterium and its bacteriophage. J. Bacteriol. 92:1535-1554. 1966.-The fine structure of a gram-negative marine bacterium, Cytophaga marinoflava sp. n., has been revealed by ultrathin sectioning and electron microscopy. Stages in the morphogenesis of the bacterial virus NCMB 385, which has been shown to be highly specific for this organism, were also demonstrated in bacterial cells fixed according to the Kellenberger technique. The bacterium possessed a cell wall, cytoplasmic membrane, and nuclear and cytoplasmic regions typical of bacterial cells. Both the cell wall and the cytoplasmic membrane showed a tripartite structure, i.e., each was composed of two dense layers separated by a low-density zone. Intracytoplasmic membrane systems were also observed, especially in dividing cells and in cells in which new viruses were being formed. As many as 18 hexagonally shaped, empty phage heads (membranes only) were observed in untreated, infected bacterial cells. Phage heads, intermediate in density to empty heads and fully condensed ones, possibly representing stages in the morphological development of the virus, were also seen.

Expression of epithelial cadherin in the developing and adult pig ovary.

Epithelial cadherin (E-cadherin) is one member of a family of intracellular calcium (Ca(2+))-dependent adhesion molecules that mediates selective cell-cell adhesion in a variety of species. Since changes in adhesive function accompany ovarian tissue development and remodeling, we were interested in studying the expression of E-cadherin during ovarian maturation in the pig. The objectives of this study were 1) to investigate the pattern of E-cadherin mRNA and protein expression during ovarian ontogeny in the pig, 2) to identify specific cells expressing E-cadherin in the mature porcine ovary, and 3) to compare E-cadherin expression in cells of morphologically healthy and atretic follicles. The results showed the presence of a 120-kDa protein, corresponding to E-cadherin, which was highest in fetal and neonatal ovaries and declined markedly (3- to 8-fold, p < 0.05) with maturity (16 wk to adult). In the adult ovary, E-cadherin was highest in ovarian surface epithelium (OSE) whereas in healthy follicles, granulosa cells had the highest levels. A significant decline (p < 0.05) in E-cadherin expression was evident in granulosa and theca cells from atretic follicles when compared with E-cadherin expression in cells of healthy follicles. A 4.2-kb E-cadherin transcript was detected in ovaries from 15-day-old pigs, and expression was markedly reduced (p < 0.05) by 16 wk of age. In the ovary of pregnancy, there was a faint E-cadherin mRNA signal, whereas in follicles the signal was stronger and uniform across follicle size. This is the first report that E-cadherin is expressed by the porcine ovary during ontogeny and that follicular and OSE cells of the adult ovary express the protein. Although the role of E-cadherin in the porcine ovary is unknown, the decline in E-cadherin expression in atretic follicular cells suggests that E-cadherin has a role in maintaining the structural integrity of the ovarian follicle during growth and development.

Structure of a marine bacteriophage as revealed by the negative-staining technique.

Valentine, Artrice F. (Georgetown University, Washington, D.C.), Peter K. Chen, Rita R. Colwell, and George B. Chapman. Structure of a marine bacteriophage as revealed by the negative-staining technique. J. Bacteriol. 91:819-822. 1966.-The morphology of a marine bacteriophage has been determined by negative-staining techniques and electron microscopy. The virus possesses a head, 600 A in diameter, and a tail which may be from 860 to 1,000 A in lenght. No tail sheath is seen. The appearance of the terminal tail structure is discussed.