Effect of the limbic cortex on regional lymph and blood flow in dogs]

Electrical stimulation of the anterior limbic area of the cortex in dogs resulted in increase of the lymph flow from the intestinal lymph duct, in enlargement of the mesenteric lymph nodes, in a fall of arterial pressure in the cranial mesenteric artery, and in decrease of the blood-stream from the homonymous vein and in the tone of the mesenteric veins. Constriction of the mesenteric veins and increase in the intestinal lymph-stream are considered to be a compensatory reaction to restore the arterial pressure to the initial level.     

Neurotrophic control of the transmembrane Cl− pump in mammalian muscle fibers

Resting membrane potential of both innervated and denervated rat diaphragm muscle fibers was investigated when the concentration of potential-producing ions was changed in the external fluid and following treatment with furosemide. It was found that equilibrium potential ( ) equalled resting potential level in innervated muscle for Cl^–, but shifts to more positive values compared with resting membrane potential following section of the nerve. Furosemide retards development of post-denervation depolarization of the muscle membrane. It is deduced that trophic influences originating from the motor nerve activates the furosemide-sensitive Cl^– influx system, leading to raised intracellular concentration of Cl^–, a shift in (E_Cl) and depolarization of the muscle membrane.S. V. Kurashov Medical Institute, Minsitry of Health of the RSFSR, Kazan'. Translated from Neirofiziologiya, Vol. 19, No. 6, pp. 766–771, November–December, 1987.     

Renal excretion capacity in hydrated desert rodents (Jaculus orientalis andJaculus deserti)

Summary The capacity to excrete a water load was studied in rats and in two desert rodents (Jaculus orientalis andJaculus deserti) adapted to either 5 or 30°C ambient temperature. The rat is able to eliminate the entire water load regardless of thermal adaptation. Cold-adaptedJ. orientalis andJ. deserti excreted 60% of the water load in comparison to 20–30% in warm-adapted jerboas.At both adaptation temperatures, antidiuretic hormone (ADH) concentration was estimated at maximum diuresis in the two desert species. Though hydration induced a significant decrease in ADH concentration in both species, its level in the plasma remained relatively high. The decrease was more pronounced inJ. orientalis thanJ. deserti.Abbreviation ADH antidiuretic hormone     

Changes in the antigenic phenotype of mouse thymocytes after exposure to chemical inducers of differentiation and ionizing radiation

Irradiation of a mouse thymocyte fraction enriched by T-lymphocyte precursors changes the antigenic phenotype of cells toward the increase of their highly differentiated forms. Similar changes in membrane marker antigens are produced by chemical inductors of differentiation and thymotropin. The changes in the cell phenotype induced by the above agents are associated with both membrane and intragenome rearrangements. The results of the experiments on preventing the expression of some antigens by puromycin and the data on the level of spontaneous genome lesions in thymocyte fractions have prompted an assumption that destabilization of the genome upon irradiation increases DNA injury above some critical level which may serve a stimulus for "sorting out" the most radiosensitive thymocyte fraction.     

Effect of acid metabolites on the osteoinductive activity of the bone matrix

The osteoinductive activity of bone matrix demineralized in acid metabolites of glycolysis and Krebs cycle have been studied in rats. The highest osteoinductive effect was reached during the demineralization in oxaloacetic acid, the lowest one--in the malic acid. The regulatory role of glycolysis metabolites and Krebs Cycle in posttraumatic osteogenesis is under discussion.     

Cyclic nucleotides in the ontogeny of the chick thymus

The dynamics of cAMP and cGMP content of the thymus homogenate from developing chick embryos and chickens was studied during ante- and postnatal development. Changes in the content of cyclic nucleotides bear an oscillatory pattern. At the early stages of embryogenesis (9 to 11 days of incubation) the content of cyclic nucleotides was low and gradually increased by 13 days of incubation. As the development proceeded, the quantitative and qualitative rearrangement of the thymus cellular composition reflected in changes in the content of cyclic nucleotides. At the same time the curves of cyclic nucleotide content became antiphasic. These reciprocal cAMP to cGMP ratios might reflect the cyclic and synchronous reproduction and functional development of the main bulk of the thymus cellular elements. The maximum content of cAMP and the minimum content of cGMP were recorded on the 17th day of embryogenesis.     

Characterization of the toxicity and cytopathic specificity of a cloned Bacillus thuringiensis crystal protein using insect cell culture

An insecticidal protein gene from Bacillus thuringiensis var. aizawal was cloned in Escherichia coli. The cloned gene expressed at a high level and the synthesized protein appeared as an insoluble, phase-bright inclusion in the cytoplasm. These inclusions were isolated by density gradient centrifugation, the isolated protein was activated in vitro by different proteloytic regimes and the toxicity of the resulting preparations was studied using insect cells grown in tissue culture. The inclusions consisted of a 130 kDa polypeptide which was processed to a protease-resist-ant 55 kDa protein by tryptic digestion. This preparation lysed lepidopteran (Choristoneura fumiferana) CFI ceils but not dipteran (Aedes albopictus) calls. When the crystal protein was activated by sequential treatment, first with trypsin and then with Aedes aegypti gut proteases, the resulting 53 kDa polypeptide was now toxic only to the dipteran cells and not to the lepidopteran cells. Thus the dual specificity of this var. aizawal toxin results from differential proteolytic processing of a single protoxin. The trypsin-activated preparation was weakly active against Spodoptera frugiperda cells. Membrane binding studies of the trypsin-activated toxin revealed a 68 kDa protein in the lepidopteran ceil membranes, which may be the receptor for this toxin.     

The interphase death of dividing cells. The effect of oxygen and the pH of the medium on the interphase death of Ehrlich ascites carcinoma cells under the action of ionizing radiation

Interphase death of in vitro irradiated (200 Gy) Ehrlich ascites tumor cells was studied as a function of oxygenation level and medium pH. The presence of oxygen both during and after irradiation as well as the increase in pH from 7.4 to 8.1 were shown to increase interphase death rate. The pronounced threshold dependence of interphase death of cells upon their concentration may be attributed to hypoxia occurring in a pericellular medium when cells concentration exceeds the threshold.     

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.     

A study of substrate specificity of DNA-methylases from Flavobacterium okeanokoites

The specificity of DNA methylase M. FokI towards oligonucleotides containing sequence 5'...GGATG.../3'...CCTAC... was investigated, and N6-methyladenine in the GGATG chain was shown to be the only product of the modification.