Collagen type I fibril packing in vivo and in vitro

Reviewed are works concerning the mechanisms of collagen (type I) fibril packing and the influence of macromolecular structure and physicochemical parameters of the medium on the process.     

Effects of organic fluorosilicone compounds on the development of tumors in mice

The influence of new synthesized fluoro-silicium-organic complexes on the virus-induced Rauscher leukosis and cell-transferred MX-11 mouse sarcoma was studied. We also studied the cytotoxic effects of these complexes in vitro in the human CaOv cells. Two complexes from seven studied were cytotoxic for CaOv cells. Five complexes from seven studied diminished the mortality of animals with MX-11 tumors on the 27-th day of observation, but the total life duration of the animals in the experimental group was the same as in controls. One complex from seven studied increased the life duration of mice with MX-11 tumors. No effects were noted in relation to mice virus-induced Rauscher leukosis.     

Erythrocyte antigen: isolation, biochemical and immunologic properties]

The authors suggest a simple method of obtaining erythrocytic antigen in considerable amounts. This antigen is of stromal origin, contains from 10 to 20% protein, and is relatively homogenous. With the concentration of from 1 to 50 microgram by protein the preparation represents a transparent solution; with greater concentrations the antigen is white, turbid, but is well dissolved and convenient for administration to the animals. In case of a single administration without any adjuvants the antigen is highly immunogenic in low doses by protein. To the optimal immunizing dose of erythrocytes (5 X 10(8)) correspond about 100 microgram of the antigen by protein. The primary response to the antigen is similar to the response to sheep red blood cells (SRBC). It is exceedingly effective for the formation of immunological memory. The level of secondary responses in the adoptive transfer to all the EAG doses always exceeded the secondary response to SRBC. By adding EAG into agar during the local hemolysis in gel test determined the avidity of the antibodies synthesized at various periods of the immune response to SRBC.     

The effect of picolinic acid and iron ions on the proliferation of SPEV cells

The effect of picolinic acid (PA) on SPEV cell proliferation is found to be different from that on normal and virus transformed NRC cells, and on spontaneously transformed CHO cells. It is shown that SPEV cells are arrested by PA at the end of G1-phase and at the beginning of S-phase and probably in G2-phase of the cell cycle. Ferrous ions remove the G1/S block induced by PA to permit the cell transfer through S-phase. On the one hand, PA chelates ferrous ions from the cells, and on the other one it inhibits the replicative DNA synthesis. It can be suggested that PA may arrest the SPEV cell growth affecting the iron-depend stable radical formation which is introduced into the active centre of ribonucleotiDE reduCTase. This results in the lower enzyme activity.     

Improved Dot-Blot Hybridization Assay for Large-Scale Detection of Potato Viruses in Crude Potato Tuber Extracts

Abstract A rapid and simple technique has been developed to enhance the sensitivity of virus detection in dot-blot hybridization assay by up to 1000 fold. The procedure generally follows that of B aulcombe et al. (1984) but includes moderate heating of the nitrocellulose filter in 10XSSC, 0.5% SDS solution at 55°C after sample application. Using this procedure, four potato viruses (PVX, PVS, PVM and PVY) were detected with cloned virus-specific ³²P-cDNA probes in 2 μl spots containing 0.2–2 pg of purufied virus (0.1–1 ng/ml). The procedure was also successfully applied for the detection of PVX, PVS, PVM and PVY in crude potato tuber extracts.     

Effect of radiation on cell interactions in the phenomenon of non-syngeneic stem cell inactivation. Changes in B-lymphocyte function after irradiation

A study was made of the changes in the mode of interaction between T- and B-lymphocytes of mouse lymph nodes with respect to the phenomenon of inactivation of non-syngeneic haemopoietic stem cells. It was shown that irradiation of B-lymphocytes with doses of 77.4--232.2 mC/kg changes their helper activity into a suppressor activity with regard to T-cell-killers having a low electrophoretic mobility.     

The secondary structure of bacteriophage DNA in situ. VIII. The reaction of sodium bisulphite with intraphage cytosine as a probe for studying the DNA-protein interaction

To obtain data on the viral nucleoprotein a study has been made of the reaction of sodium bisulphite with cytosine in the intraphage DNA of the phage Sd. The CHlO4 hydrolysates of the bisulphite-modified phage Sd have demonstrated a decrease of 18% in the cytosine content and the presence of the products with the properties of cytosyl-amino acids (the main amino acid responsible for the DNA-protein interaction involving cytosine is lysine). But when prior to hydrolysis the modified phage was disintegrated under mild conditions in 0.1--1 M NaCl solution or Tris-HCl buffer (pH 7), neither the decrease in the cytosine content nor cytosyl-amino acids have been found. An exception is the heating of the phage at 70 degrees C in a medium containing 0.05 M phosphate buffer (pH 7.9--8.5), when an 18% decrease in the cytosine content and subsequent appearance of cytosyl-amino acids have also been observed. The presence of cytosyl-amino acids which are the nucleotide-protein cross-links is confirmed by the results of viscometry, equilibrium centrifugation in cesium sulphate gradient and determinations of the survival percentage. It is suggested that the reaction between bisulphite and cytosine in the phage Sd stops at the stage of the intermediate product C5-C6-dihydro-C6-sulphopyrimidine whose amino group is shielded by interaction with protein (product VII). This product can exist only under in situ conditions: with disintegration of nucleoprotein (destruction of phage particles or ejection of the DNA) in phosphate-free media the product VII reverts into the initial cytosine. Under the conditions of acid hydrolysis or destruction of phage in the presence of phosphate ions product VII undergoes transamination with cleavage of SO3 and restoration of the C5-C6 double bond producing cytosyl-amino acids. The factors determining the stability of the product VII are discussed.