Frequency, time and type of metastasis of different transplantable tumors in mice

The character of metastasis of 9 strains of transplantable mouse tumours in conventional subcutaneous inoculation was studied. There were differences in the frequency, intensity, and types of metastasis of different tumours. Periods of onset of metastases of Lewis lung carcinoma and RL-67, and also of sarcoma-37 were established. Sarcoma, Lewis and RL-67 lung carcinomas, adenocarcinoma of the colon AKATOL, Cloudman's melanoma and B-16 metastasized most intensively. Sarcoma-37 metastasizing into the regional and remote lymph nodes, Lewis lung carcinoma and melanomas metastasizing into the lungs, RL-67 lung carcinoma metastasizing into the lungs, kidneys, adrenal glands, ovaries, the heart, and also adenocarcinoma of the colon AKATOL metastasizing into the lymph nodes and the liver can be used as models for the research in the field of drug action upon metastases and the metastasis process.     

The primary structure of the operons coding for Shigella dysenteriae toxin and temperature phage H30 shiga-like toxin

Nucleotide(nt) sequences were determined for the toxin (SHT) operon present in the chromosome of Shigella dysenteriae 1 and for the shiga-like toxin (SLT) operon found in the lambdoid phage H30 genome. The coding sequences of the sht and slt genes differ in 4 nt with 1 nt change responsible for an amino acid replacement. The deduced amino acid sequence in the A chain of the toxins is highly homologous to that of the A chain of ricin, a plant toxin. SHT-coding mRNAs were detected by mapping the 5' termini and using blot-hybridisation; one of them was more abundant and coded only for the B subunit of SHT while the other (bi-cistronic mRNA) encoded both subunits. An IS element related to the IS3 element of Escherichia coli was found in the chromosome of S. dysenteriae near the sht operon.     

High-frequency components of cortical potentials and their phase-coherent characteristics during the acquisition of motor-food conditioned reflexes in dogs

Phase-coherent characteristics of neocortex background electrical activity were studied in a wide frequency range (1-100 Hz) during interstimulus periods in the process of elaboration of motor alimentary conditioned reflexes in dogs. It was shown that the process of learning led to a considerable increase of the part of high (greater than 0.75) and significant (0.5-0.75) coherences, and also of small (0 +/- 15 degrees) and accounted (+/- 16 - +/- 30 degrees) phasic shifts as compared with the state of calm wakefulness. This increase lay mainly in the high-frequency range (40-100 Hz). The analysis of the interregional relations showed that they differed not only by values of phase-coherent characteristics, but also by distributions of the latter. The obtained data testify that the state of activation is manifested both in the rise of frequency of potentials oscillations and in the increase of their synchronization.     

Conjugation transfer of the plasmid pAMbeta1 into various Bacillus species

Streptococcal broad host range plasmid pAM beta 1 was transferred by a conjugation-like process from Streptococcus faecalis to 13 strains of different Bacilli species. In intraspecies matings the frequencies of transfer of pAM beta 1 varied from 2.10(-5) to 1.10(-8). As it was shown by comparative analysis the frequency of transfer and stability of the maintainance of plasmid pAM beta 1 in Bacilli were not connected. Molecular weight and restriction pattern of pAM beta 1 DNA isolated from Bacilli were the same as those of pAM beta 1 DNA from Streptococcal donor strain.     

Mechanical properties of the red cell membrane skeleton: analysis of axisymmetric deformations

The mechanical properties of erythrocyte membrane composed of a membrane bilayer and membrane skeleton are considered. Two membrane models are described: the model of free boundaries (MFB) and the model of immobilized boundaries (MIB). In MFB, the skeleton is assumed to be attached to the bilayer at a finite number of points, whereas MIB allows the interaction of each spectrin filament with the bilayer along its whole length. For MFB an estimate was made of the mechanical strain generated in the membrane by sucking erythrocytes into a micropipette. The existence of the deformation threshold is demonstrated, below which no mechanical strain, except that of bending, appears in the membrane. Thus only deformations exceeding this threshold result in strain. The relationship between the applied tension and the height of erythrocyte "tongue" sucked into a micropipette was determined. The MIB characteristics correspond to the model of Evans: strains in the membrane are generated at any deformation, however small, i.e. the threshold is equal to zero. A basic feature of this model is quite a different distribution of the skeleton deformations in the membrane. A comparison of the theoretical models and experimental data demonstrated the possibility of either MFB or MIB occurring, depending on the characteristic measurement time.     

Water Balance in Cucumis Plants, Measured by Nuclear Magnetic Resonance, I

In this paper we demonstrate the study of plant water balanceby the non-invasive measurement of tissue water content andwater flow using proton nuclear magnetic resonance (NMR). Sapvelocity and flux were measured independently in the presenceof an excess of stationary tissue water. The instrumentationdescribed allows automated and unattended measurement of flow-and water content-variables in a well-defined region of theplant over periods of several days, with a time resolution betweensuccessive measurements of c. 5 s. Using this apparatus theeffect of changes in light intensity (day/night rhythm) andrelative humidity on stem tissue water content as well as onthe velocity and flux of xylem sap in the stem were investigatedin a cucumber plant. The results are in agreement with predictionsfrom a simple model for plant water balance, which is basedon water potential, flow rate and resistance to flow. As longas only transpiration is varied, flow rate and water content(or potential) are affected in opposite ways as demonstratedin this paper. In contrast, the model predicts that changesin uptake (resulting from changes in, for example, root resistance)will induce changes in water content and flow in the same direction.An experimental verification of this prediction is given ina subsequent paper, where, in addition, the NMR results arecompared to those obtained with a dendrometer. Key words: Water balance model, Cucumis sativus L., flow, water content, NMR, water balance measurement     

Interrelation of the dynamics of antigen intake into bone marrow and the proliferation of hematopoietic stem cells

As it is previously shown (Tsyrlova et al., 1986), the level of humoral immune response is not only determined by the reaction of peripheral lymphoid system on antigenic effect, but also is bound up with the observed stem blood cell (SBC) proliferation in bone marrow (Frindel et al., 1976, Kozlov et al., 1982). Dynamics of label accumulation in bone marrow was examined when injecting antigen--sheep red blood cells labeled by radioisotope 51Cr, 125I. The peak of label accumulation in bone marrow, accompanied by the increase in proliferative SBC, was observed on the 3rd day after antigen injection. Furthermore in the course of immunization 51Cr labeled macrophage assortment was changed in time in such a way that a greater number of macrophages was accumulated in bone marrow on the 3rd and 4th days in the immunized animals in comparison with the intact ones. The macrophages in bone marrow are likely to take part in antigen uptake and to mediate its effect on SBC proliferation.     

Tightly bound adenosine diphosphate, which inhibits the activity of mitochondrial F1-ATPase, is located at the catalytic site of the enzyme

The binding of one ADP molecule at the catalytic site of the nucleotide depleted F1-ATPase results in a decrease in the initial rate of ATP hydrolysis. The addition of an equimolar amount of ATP to the nucleotide depleted F1-ATPase leads to the same effect, but, in this case, inhibition is time dependent. The half-time of this process is about 30 s, and the inhibition is correlated with Pi dissociation from the F1-ATPase catalytic site (uni-site catalysis). The F1-ATPase-ADP complex formed under uni-site catalysis conditions can be reactivated in two ways: (i) slow ATP-dependent ADP release from the catalytic site (tau 1/2 20 s) or (ii) binding of Pi in addition to MgADP and the formation of the triple F1-ATPase-MgADP-Pi complex. GTP and GDP are also capable of binding to the catalytic site, however, without changes in the kinetic properties of the F1-ATPase. It is proposed that ATP-dependent dissociation of the F1-ATPase-GDP complex occurs more rapidly, than that of the F1-ATPase-ADP complex.     

Interaction of immobilized DNA with alkaline metal and ammonium ions

Ion exchangers with various capacities (0.1-0.2 mg-equiv/g of dry gel) are synthesized by means of immobilization of DNA in polyacrylamide gel. Exchanges of alkali metal cations and ammonium are studied on these exchangers and selectively coefficients are determined. The following selectivity series of immobilized DNA in reference to the above-mentioned cations is stated: Li+ greater than or equal to NH4+ greater than or equal to Cs+ greater than Rb+ greater than K+ greater than or equal to Na+. The peculiar properties of Li+ and NH4+ in this series are noted and a possible explanation of this fact is offered. A supposition regarding the reduced activity of water in the polyacrylamide gel containing DNA is made.