Effects of low intensity infra-red laser irradiation on ultrastructure and proliferation of liver cells in experimental hepatitis and cirrhosis]

With the aid of light, electron transmission and scanning electron microscopy and radioautography and stereometry, the influence of low-intensive laser irradiation (LILI) (infrared) was studied in normal rat liver and in experimental cirrhosis and hepatitis. It was revealed that arsenide-gallium laser irradiation causes the change of intracellular structure. These changes show the intensification on their specific function manifest in an increase of relative volume of intracellular structures. The changes of microvessels show the activation of microcirculation. The elevation of the index of the labelled nuclei testify to increased proliferation. The similar influences of LILI on the liver ultrastructure and proliferation in hepatitis and cirrhosis are accompanied by the reduction of the pathological changes of the liver--the hepatocytes oedema, granular, vacuolar and fatty dystrophy.     

The immunostimulating properties of cholecystokinin octapeptide and its fragments]

Immunostimulating properties of cholecystokinin octapeptide (CCK-8) were evaluated in experiments on adult normal and thymectomized mice, in vitro. It was shown that CCK-8 stimulates IgM-PFC production to SRBC, but does not change the immune response to Vi-antigen. CCK-8 increases the number of Thy-I+ spleen T cells and restores thymus-dependent immune response in thymectomized mice. CCK-8 has no effect on neutrophil phagocytosis activity in vitro. The immunostimulating activity of CCK-8 is related mainly to C-terminal fragment (identical to pentagastrin tetrapeptide) since the N-terminal CCK-8 tetrapeptide displays negligible effect in all tests.     

Organization of reflex sympathetic influence on rate and force of cardiac contraction]

In acute experiments on 21 cats it was proved that the change of afferent impulse on vagus nerves by means of either freeze-block or electrostimulation of their central ends results in differential reflex influences on rhythm and force of the cardiac contractions caused by sympathetic nervous system. The cut of the lower cardiac nerves may cause 'break-up' of the observed reflex, removing or inverting its ino- or chronotropy component. The given phenomenon was revealed in the experiments with high arterial pressure and with absence of tonic chronotropy influences of the left lower cardiac nerve.     

Evoked potentials and electric resistance of the cerebral cortex under the effects of strychnine and atropine]

The effect of strychnine and atropine on the amplitude of the evoked potentials (EP) of the cerebral cortex was studied. It was shown, that both drugs increased amplitude of the EP. When we used strychnine, increased amplitude of the EP determined modification of the electrical resistance and current sources of the electrical field of the EP. Atropine did not change electrical resistance and in this case only electrical current sources determined modification of the EP.     

Molecular architecture of the neurofilament. I. Subunit arrangement of neurofilament L protein in the intermediate-sized filament

Using the smallest subunit (NF-L) of a neurofilament and a glial fibrillary acidic protein, the subunit arrangement in intermediate filaments was studied by low-angle rotary shadowing. NF-L formed a pair of 70 to 80 nm rods in a low ionic strength solution at pH 6.8. Two 70 to 80 nm rods appeared to associate in an antiparallel manner with an overlap of about 55 nm, almost the same length as the alpha-helix-rich central rod domain of intermediate filament proteins. The overlap extended for three-beaded segments, present at 22 nm intervals along the pairs of rods. The observations that (1) 70 to 80 nm rods were a predominant structure in a low ionic strength solution at pH 8.5, (2) the molecular weights of the rod and the pair were measured by sedimentation equilibrium as 190,000 and 37,000 respectively, and (3) the rods formed from the trypsin-digested NF-L had a length of about 47 nm, indicated that the 70 to 80 nm rod is the four-chain complex and the pair of rods is the eight-chain complex. Similar structures were observed with glial fibrillary acidic protein, indicating that these oligomeric structures are common to other intermediate filament proteins. NF-L assembled into short intermediate-sized filaments upon dialysis against a low-salt solution containing 1 to 2 mM-MgCl2 at 4 degrees C. The majority of these short filaments possessed four or five-beaded segments, suggesting that the pair of rods were arranged in a half-staggered fashion in neurofilaments. On the basis of these observations, we propose the following model for the intermediate filament subunit arrangement. (1) The four-chain complex is the 70 to 80 nm rod, in which two coiled-coil molecules align in parallel and in register. (2) Two four-chain complexes form the eight-chain complex by associating in an antiparallel fashion with the overlap of the entire central rod domain. (3) The eight-chain complex is the building block of the intermediate filament. The eight-chain complexes are arranged in a half-staggered fashion within the intermediate filament.     

Effect of sonication on paraffin-embedded tissue preparation for DNA flow cytometry

Since the publication of paraffin block extraction procedures, flow cytometric analysis of DNA ploidy and S-phase of tumor specimens has been widely applied. DNA aneuploidy, DNA tetraploid (elevated G2/M), and elevated S-phase are clinically significant in some tumor systems. True DNA tetraploid cell lines will contain a large 4c population and perhaps an 8c population; samples with cell aggregates will also contain a 6c population. Microscopic examination of samples having a 6c peak revealed nuclei with adhering debris and doublets, triplets, and larger nuclear aggregates. After sonication, a uniform suspension of single nuclei without adherent debris was seen. In addition to reducing the percent of G2/M cells, sonication also reduced S-phase percent such that it was closer to the bromodeoxyuridine labeling index. The DNA ploidy classification of specimens was also compared pre- and post-sonication. Four of 96 breast cancer samples changed classification; all were specimens in which the histogram became cleaner and a small DNA aneuploid peak became apparent after sonication.     

Refined crystal structure of the phosphorylase-heptulose 2-phosphate-oligosaccharide-AMP complex

The crystal structure of phosphorylase b-heptulose 2-phosphate complex with oligosaccharide and AMP bound has been refined by molecular dynamics and crystallographic least-squares with the program XPLOR. Shifts in atomic positions of up to 4 A from the native enzyme structure were correctly determined by the program without manual intervention. The final crystallographic R value for data between 8 and 2.86 A resolution is 0.201, and the overall root-mean-square difference between the native and complexed structure is 0.58 A for all protein atoms. The results confirm the previous observation that there is a direct hydrogen bond between the phosphate of heptulose 2-phosphate and the pyridoxal phosphate 5'-phosphate group. The close proximity of the two phosphates is stabilized by an arginine residue, Arg569, which shifts from a site buried in the protein to a position where it can make contact with the product phosphate. There is a mutual interchange in position between the arginine and an acidic group, Asp283. These movements represent the first stage of the allosteric response which converts the catalytic site from a low to a high-affinity binding site. Communication of these changes to other sites is prevented in the crystal by the lattice forces, which also form the subunit interface. The constellation of groups in the phosphorylase transition state analogue complex provides a structural basis for understanding the catalytic mechanism in which the cofactor pyridoxal phosphate 5'-phosphate group functions as a general acid to promote attack by the substrate phosphate on the glycosidic bond when the reaction proceeds in the direction of glycogen degradation. In the direction of glycogen synthesis, stereoelectronic effects contribute to the cleavage of the C-1-O-1 bond. In both reactions the substrate phosphate plays a key role in transition state stabilization. The details of the oligosaccharide, maltoheptaose, interactions with the enzyme at the glycogen storage site are also described.     

Preservation of plastic properties of synaptic transmission in long-lasting hippocampal slices under the effects of a peptide analog of piracetam, L-pGlu-D-Ala-NH2

The tetanic stimulation of the Schaffer collaterals (SC) in rat hippocamp slices after 6 hrs in vitro conditions did not produce long-term potentiation (LTP) of the field response amplitude in the CA1 pyramidal cell layer. In contrast, LTP after the late tetanization was well preserved in the slices that were perfused for 20 minutes with 0.5 mkM L-pGlu-D-Ala-NH2 (PGAA) after 4-4.5 hrs in vitro. There were no significant reactivity changes during the perfusion of the slices with this drug concentration. Two other drugs with nootropic activity, piracetam (100 mkM) and gamma-hydroxybutyrate (100 mkM, Na-salt) did not prevent the disappearance of LTP in the late period in vitro, while enhanced the reactivity during perfusion period. The maintenance of the plastic properties of the SC-CA1 synaptic transmission under the influence of PGAA is thought to be the result of some specific interaction of the drug with LTP induction mechanisms. LTP damaged in the late period in vitro might be a new model of memory disturbances and this model can turn out to be useful for the comparative estimation of the effectiveness of the drugs with proposed nootropic activity and for the analysis of the possible mechanisms of their action.