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.     

A division inhibitor and a topological specificity factor coded for by the minicell locus determine proper placement of the division septum in E. coli

The E. coli minicell locus (minB) was shown to code for three gene products (MinC, MinD, and MinE) whose coordinate action is required for proper placement of the division spetum. Studies of the phenotypic effects of expression of the three genes, alone and in all possible combinations, indicated the following: cell poles contain potential division sites that will support additional septation events unless specifically inactivated; the minC and minD gene products act in concert to form a nonspecific inhibitor of septation that is capable of blocking cell division at all potential division sites; and the minE gene codes for a topological specificity factor that, in wild-type cells, prevents the division inhibitor from acting at internal division sites while permitting it to block septation at polar sites.     

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.     

Prediction of "hot spots" in interleukin-2 based on informational spectrum characteristics of growth-regulating factors. Comparison with experimental data

The Resonant Recognition Model (RRM) is a theoretical method for analysis of protein and nucleotide sequences, based on the Fourier transform of the numerical representation of sequences. The amplitude spectrum of this transform is designated Informational Spectrum (IS). There are certain common frequencies in IS of growth-regulating factors. These characteristic frequencies may correlate with their roles in cell proliferation and metabolism, and in antitumor activity. IS of IL-2 has prominent characteristics in the main frequency domain of growth factors, frequency domain of antitumor factors, and frequency domain characteristic for IL-2-alpha receptor. By means of the inverse method for these 3 domains, the amino acids in the sequence of human IL-2 that may be relevant to its biological function, the so-called "hot spots", were predicted. The most probable hot spots, obtained in this way, are in the potential binding site of IL-2 to its receptor, which agrees with experimental data.     

Occurrence of the hepatotoxic cyanobacterium Nodularia spumigena in the Baltic Sea and structure of the toxin

Water blooms formed by potentially toxic species of cyanobacteria are a common phenomenon in the Baltic Sea in late summer. Twenty-five cyanobacterial bloom samples were collected from open and coastal waters of the Baltic Sea during 1985 to 1987, and their toxicity was determined by mouse bioassay. All of 5 bloom samples from the southern Baltic Sea, 6 of 6 from the open northern Baltic Sea (Gulf of Finland), and 7 of 14 Finnish coastal samples were found to contain hepatotoxic cyanobacteria. Nodularia spumigena and Aphanizomenon flos-aquae occurred together in high amounts in blooms from the open-sea areas. In addition, coastal samples contained the species Anabaena lemmermannii, Microcystis aeruginosa, and Oscillatoria agardhii. Eighteen hepatotoxic N. spumigena cultures were isolated from water bloom and open-sea water samples. High-pressure liquid chromatographic analysis of both hepatotoxic bloom samples and Nodularia strains showed a single toxic fraction. The toxin concentrations of the blooms were less than or equal to 2.4 mg/g of freeze-dried material, and those of laboratory-grown cultures were 2.5 to 8.0 mg/g of freeze-dried cells. A single toxin was isolated from three N. spumigena-containing bloom samples and three N. spumigena laboratory isolates. Amino acid analysis and low- and high-resolution fast-atom bombardment mass spectroscopy indicated that the toxin from all of the sources was a cyclic pentapeptide (molecular weight, 824) containing glutamic acid, beta-methylaspartic acid, arginine, N-methyldehydrobutyrine, and 3-amino-9-methoxy-2,6,8-trimethyl-10-phenyl-4,6-decadienoic acid.(ABSTRACT TRUNCATED AT 250 WORDS)     

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.