Spread of fast thermowaves through the cerebral cortex produced by visual stimulation

Thermowaves spreading through the cerebral cortex were observed and investigated during acute experiments on white rats using a new technique — that of thermoencephaloscopy (TES) through the intact skull. These waves were induced by regular visual stimulation (at intervals of 1.5–3 min) or by initiating one of the flashes and spread through the cortex along trajectories of five basic types; amplitude of thermowaves: 0.005–0.1°C; length: 10–15 mm; duration 1.2–11.4 sec; velocity: 1–33 mm/sec; extent of pathway: 2–56 mm. They appeared with a high degree of probability (of 0.92) during the interval between 15 sec before and 26 sec after the flash. Numbers of moving waves declined by the point of stimulus application and rose by 7–8 sec after the flash. Waves arose in 50% of cases in the contralateral visual cortex (areas 17 and 18a), spreading to the midline and crossing to the ipsilateral hemisphere (areas 17, 18a, and 7). Local waves moving along a circular trajectory were also discovered in the contralateral visual cortex. Several types of wave, differing in trajectory, also arose in the ipsilateral visual cortex. Mechanisms and possible significance of this effect are examined.Institute of Higher Nervous Activity and Neurophysiology, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 21, No. 4, pp. 467–475, July–August, 1989.     

Human prenatal palatal closure related to skeletal maturity of the jaws

The purpose of the present study was to elucidate the stages of skeletal maturation of the maxilla and the mandible at the time of soft tissue palatal closure. Similar studies were not found in the literature. This investigation was based on maxillae and mandibles from 19 human embryos/fetuses selected by visual inspection of palatal structures, eight fetuses "just before palatal closure," and 11 fetuses "just after palatal closure." The findings are related to formerly described skeletal developmental stages in the maxilla, to stages in the symphysis menti region, and to development in the mandibular condylar region. The present study revealed that elevation of the palatal shelves takes place at a specific stage of maxillary skeletal maturity (stage Max III), at a time of mandibular development characterized by absence of condylar cartilage and by constancy in symphysis menti maturity (stage SM I). Knowledge of the normal sequence of prenatal skeletal development is considered essential for understanding the abnormal sequence of skeletal development.     

Spectral features of amines of 2-phenylbenzazoles upon interaction with DNA

Absorption and fluorescent spectra of various synthetic aminophenyl derivatives of benzoxazole, benzothiazole and benzimidazole have been studied to estimate the efficiency of their binding with DNA. The significance of different functional groups of the fluorochromes for their interaction with DNA was determined, and main demands are formulated to the compounds to be used as potential fluorescent probes for DNA studies.     

Conformation-activity relations of dermorphin and its pentapeptide analogs

Low-energy peptide backbone structures of dermorphin (DM), amide of its N-terminal pentapeptide (DM 1-5) and DM 1-5 analogues with substitutions of Gly4 for Leu, D-Gln, Aal or Tal were determined by energy calculations. The above analogues were shown to possess different affinities toward opiate receptors of mu-type. The comparison of low-energy backbone structures of DM, DM 1-5 and its analogues resulted in development of the dermorphin "biologically active" conformation being characteristic of its binding with mu-type receptors. The specific binding of dermorphin to this receptor apparently depends on the conformation of the whole N-terminal pentapeptide.     

Cyclic analogs of des-Arg9-[Leu8]bradykinin

Four cyclic derivatives of des-Arg9[Leu8]bradykinin have been obtained by classical methods of peptide chemistry. They are cyclo-(-X-Arg-Pro-Pro-Gly-Phe-Gly-Pro-Leu-), where X=Lys or none, and cyclo-(Y-Arg-Pro-Pro-Gly-Phe-Ser-Pro-Leu-), where Y= Lys or Orn. Peptide bonds have been formed by the pentafluorophenylester method, and cyclization has been carried out in a diluted dioxane solution with 40% yield. Subsequent cleavage of protecting groups was made by treatment with hydrogen fluoride. The products obtained were purified by droplet counter-current chromatography. These substances liberate histamine from the rat mast cells comparably to bradykinin and fail to produce myotripic and vascular effects.     

Isolation and physico-chemical properties of a protein, included in an endotoxin from Yersinia pseudotuberculosis

A major protein of the endotoxin from Yersinia pseudotuberculosis was isolated from the complex lipid A--protein by treatment with SDS and triton X-100 followed by gel-chromatography on Sephacryl S-300. Protein has apparent molecular mass 40 kDa and alanine as N-terminal amino acid residue. CD and IR spectroscopy conformational changes of the protein molecule in the process of its isolation. The thermal and pH stabilities of the protein were investigated by the methods of intrinsic fluorescence and differential scanning microcalorimetry. The isolated protein revealed two thermal transitions (at 30-35 and 50-55 degrees C), which depend on Ca2+ concentration.     

Symmetry and dimensions of membrane-bound nicotinic acetylcholine receptors from Torpedo californica electric tissue: rapid rearrangement to two-dimensional ordered lattices

Computer-aided image-averaging methods are applied to different preparations of membrane-bound nicotinic acetylcholine receptor. Circular harmonic averaging (CHA), a novel, reference-independent averaging method developed by W. Kunath and H. Sack-Kongehl [1989) Ultramicroscopy 27:171-184) allows analyzing images of single molecules of the receptor in its native membrane-bound state. The five subunits of the receptor are clearly resolved. At the resolution obtained (approximately 20 A) no differences were observed with resting and agonist-desensitized receptors. A method is proposed for rapidly arranging the acetylcholine receptors to ordered lattices. Depending on the conditions, tetragonal or hexagonal, two-dimensional lattices can be obtained within 2 to 6 days at 4 degrees C. Analysis by CHA shows that the receptor molecules preserve their gross structure and dimensions in these membranes, but that they are randomly oriented. Both lattices, therefore, do not represent true two-dimensional crystals.     

Correction of lipid peroxidation in stress with the peptide bioregulator thymopentin

Experiments on rats subjected to acute stress have revealed protective effect of thymopentin pentapeptide on somatic disorders and the state of the antioxidation system and the processes of lipid peroxidation in blood and brain.     

Characteristics of the differentiation of hematopoietic stem cells of the bone marrow in experimental lesions of the liver

The liver lesion in the CBA mice has been induced by administration of one of three agents five times every day; gamma-globulin fraction of antihepatocytotoxic serum in doses of 4.8 and 7.7 mg of protein per 100 g of body mass; gamma-globulin fraction of normal rabbit serum and bovine serum albumin in a dose of 4.8 mg of protein; three- four- or five-fold introduction of carbon tetrachloride in a dose of 0.5 ml per 100 g of body mass with oil (1:1) each three days; calibrated stenosis of the portal vein was produced. The total number of hemopoietic stem cells in the bone marrow was estimated by the colony-forming unit/spleen assay. Histological analysis of the colony-forming units was applied. The liver lesion was accompanied by a decrease in the ratio of the erythroid/granulocytic colonies.