Electrophysiologic effects of serotonin on atrioventricular conduction in dogs

In 12 anaesthetized dogs acute effects of serotonin on the atrioventricular conduction system were studied by obtaining intracardiac electrograms. The significant increase in the heart rate and decrease in aortic pressure elicited by an intravenous infusion of 50 mg/kg.min serotonin for 30 minutes were comparable to those observed in previous investigations. Our data indicate a serotonin induced acceleration of the sinus node pacemaker and atrioventricular conduction by direct and indirect mechanisms.     

NMR studies of the conformational change in human N-p21ras produced by replacement of bound GDP with the GTP analog GTP gamma S.

1H-Detected 15N-edited NMR in solution was used to study the conformational differences between the GDP- and GTP gamma S-bound forms of human N-p21ras. The amide protons of 15N-labeled glycine and isoleucine were observed. Resonances were assigned to residues of particular interest, glycines-60 and -75 and isoleucines-21 and -36, by incorporating various 13C-labeled amino acids in addition to [15N]glycine and [15N]iosleucine and by replacing Mg2+ by Co2+. When GTP gamma S replaced GDP in the active site of p21ras, only 5 of the 14 glycine amide resonances show major shifts, indicating that the conformational effects are fairly localized. Responsive glycines-10, -12, -13, and -15 are in the active site. Gly-75, located at the far end of a conformationally-active loop and helix, also responds to substitution of GTP gamma S for GDP, while Gly-77 does not, supporting a role for Gly-75 as a swivel point for the conformational change. The amide proton resonances of isoleucines-36 and -21 and a third unidentified isoleucine also undergo major shifts upon replacement of GDP by GTP gamma S. Thus, the effector-binding loop containing Ile-36 is confirmed to be involved in the conformational change, and the alpha-helix containing Ile-21 is also shown to be affected.     

Development and characterization of a human cell line from an ovarian mixed mullerian tumor (carcinosarcoma)

Summary A cell line derived from a human ovarian carcinosarcoma was established in tissue culture and in nude mice. Two sublines, LDF and HDF, separated by discontinuous density centrifugation were also established from the parent line JoN. The cloning efficiency of the JoN line was 21%. Morphologic features of adenocarcinoma cells characteristic of the parent JoN cells were retained in the sublines and clones; all lines showed the same karyotype and DNA content (pseudodiploid and pseudotetraploid). Keratin, as demonstrated immunohistochemically, was strongly expressed in the parent line JoN and the xenograft tumor, but not at all in the LDF sublines and only moderately in the HDF sublines. Vimentin, however, was expressed in neither the parent line JoN nor the xenograft tumor, but was present in both sublines. Transglutaminase and plasminogen activator activity was high in the parent line JoN. Neither, sublines nor clones showed the same high enzyme activity as the parent line. It is concluded that this human tumor line JoN is comprised of epithelial cells, capable of multidirectional differentiation.     

Comparative analysis of the HBsAg level in human blood preparations

A total of 218 batches of blood preparations produced from different raw materials have been studied by means of enzyme immunoassay kits (Abbott Laboratories, USA). The assays have revealed that the preparations under study are nonstandard with respect to the content and isolation rate of HBsAg, the marker of hepatitis B virus. These data necessitate search for the ways of improving the quality of blood preparations.     

Contractile properties of reinnervated skeletal muscle and their relation to the degree of nerve damage

Experiments with 22 rats have shown that the anterior tibial muscle in the stage of incomplete reinnervation is marked by decreased force and retardation of the semi-relaxation of an isometric contraction. In completely reinnervated muscles, the changes in the contractility are determined by the degree of nerve damage. The group of animals with the sciatic nerve injury demonstrated the contractility characteristic of a slower muscle, in contrast to the group with the fibular nerve damage.