The effect of morphine on RNA synthesis in some brain structures of rats with various narcological resistance

Different incorporation of³H-uridine in RNA and increased RNA synthesis after the addition of morphine are demonstrated in all brain structures of resistant rats, as well as in the cortex, nucleus accumbens, griseum centrale, and nucleus ventriculus hypothalami of prone rats. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 117, N ^o 1, pp. 100–102, January, 1994     

Transport of nitrullin,a new nitrosoalkylurea derivative,into tumor and normal cells

The interaction between the antitumor drug nitrullin and the system providing the transport ofl-lysine into P388 leukemic cells and murine enterocytes is studied. Two types of lysine carriers with low and high affinity for the substrate are identified. Nitrullin competitively inhibits the transport of³H-lysine and shows the same affinity for both carriers. It is similar to that of lysine for the low-affinity carrier and is 80-fold lower than lysine affinity for the high-affinity carrier. Kinetic characteristics of the low-affinity transport of³H-lysine and K_i of nitrullin are similar to those obtained at a reciprocal substrate-inhibitor ratio. Nitrullin does not inhibit active transport of³H-lysine into enterocytes against the background of considerable (70%) passive diffusion. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 122, No. 12, pp. 648–650, December, 1996     

Functional nuclear suppressor of mitochondrialoxi2 mutations in yeast

Summary A semidominant nuclear suppressor, callednam6, ofoxi2-V276 mitochondrial mutation has been isolated and characterized. The nuclear character ofnam6 was proved by its retention inrho° strains, lack of mitotic segregation in diploids and meiotic 2:2 segregation in tetrads. The specificity ofnam6 was tested on 315mit ^– mutations of four mitochondrial genes (oxi1, oxi2, oxi3, andcob-box). It suppresses clearly only three mutations in theoxi2 gene, restoring partially or completely cytochrome aa₃ formation. The results suggest a functional character of the suppression.     

Cellular mechanism of force development in cat middle cerebral artery by reducedPCO2

These studies were undertaken to determine the effect of reducing aPCO₂ below physiological levels on cat middle cerebral artery. Upon reduction ofPCO₂ from 37 to 14 torr (pH 7.4) we observed membrane depolarization and force development. ReducingPCO₂ decreased the slope of theE _m vs. log [K]_o curve and increased the slope of the steady-state I/V relationship suggesting that the change inE _m was due to reduction of outward K⁺ conductance (g _k). Elevation of pH from 7.37 to 7.6 had a very similar effect on these cerebral arterial muscle cells, depolarizing the muscle membrane (reducing theE _m vs. log [K]_o curve) and increasing the slope of the I/V relationship to statistically equivalent values as reduction ofPCO₂. ReturningPCO₂ from 14 to 37 torr rapidly relaxed these preparations, but only transiently. This relaxation was followed by a rebound contraction within 3 min, demonstrating a transient nature for the action of elevatingPCO₂ in cerebral arteries. The response to changing pH_o followed a slower time course but did not change with time. These studies demonstrate that both elevated pH_o and reducedPCO₂ activate cerebral arterial muscle by a mechanism which includes reduction ing _k. However, it can not be determined if these similar responses and reduction, ofg _k are mediated by changing pH_i or mediated through different mechanisms. It is possible that pH_o andPCO₂ can modify cerebral arterial tone by direct mechanisms and not necesarily by their effect on pH_i. It is clear, however, that reduction ofPCO₂ and elevation of pH_o both activate cerebral arterial muscle by a mechanism which includes reduction ofg _k.This study was supported by NIH grant no. HL-32871. Dr. Harder is an established investigator of the American Heart Association     

Effect of human defensins on the cytoplasmic Ca2+ content in platelets

The effect of the total fraction of human defensins (HNP-1, HNP-2, and HNP-3) on the cytoplasmic Ca²⁺ content ([Ca²⁺]_i) in the platelets of healthy donors was studied. At concentrations of 0.1–40 μg/ml and an incubation time of 10 min defensins have no effect on [Ca²⁺]_i in platelets labeled with Fura-2AM. However, at higher concentrations (100 μg/ml) they increased platelet [Ca²⁺]_i. In addition, defensins (40 μg/ml) inhibited the Ca²⁺ increase in platelets induced by thrombin, adenosine diphosphate, and the lipopolysaccharide ofS. typhimurium endotoxin. The most pronounced inhibitory effect was observed in a suspension of thrombin-stimulated platelets. It is shown that the effect of human defensins on the functional activity of platelets is due to the alterations in the intracellular Ca²⁺. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 118, N ^o 12, pp. 600–603, December, 1994     

The pharmacokinetics of (125I) 3-deoxy-3-iodine glucose on experimental tumor modelsin Vivo

The dynamics of¹²⁵I distribution is studied in rats with induced tumors of the prostate and mammary gland for intravenous administration of¹²⁵I-3D-G. It is found that 80% of the activity is eliminated in the first 24 hours. A relatively high level of¹²⁵I accumulation is found in necrotically altered regions of the tumor. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 117, № 3, pp. 294–295, March, 1994.     

Inheritance of morphine sensitivity in (WAG/G-fischer-344) F1 rats

The effects of morphine on the pain sensitivity and motor activity of progeny obtained by different variants of crossing purestrain WAG/G and Fischer-344 rats are studied. Four groups of rats were investigated: WAG/G (male and female WAG/G rats were crossed), Fischer-344 (Fischer-344 male and female), F/W (Fischer-344 male, WAG/ G female) F₁ hybrids, and W/F (WAG/G male, Fischer-344 female) F₁ hybrids. It is shown that the inheritance of individual features of sensitivity to the analgetic effect of morphine as well as of pain sensitivity is apparently sex-linked. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 120, N ^o 9, pp. 291–293, September, 1995 Presented by V. N. Yarygin, Member of the Russian Academy of Medical Sciences     

Binding of3H-diazepam in rat brain eleven months after termination of corazole kindling

Binding of³H-diazepam in rat cerebellum decreases by 14% (p<0.05) 11 months after termination of kindling and one day after injection of a test dose of corazole (30 mg/kg), while it increases by 19.5% after a single injection of a convulsive dose of corazole (50–75 mg/kg). No changes are found in the cortex. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 117, N ^o 2, pp. 135–137, February, 1994 Presented by G. N. Kryzhanovskii, Member of the Russian Academy of Medical Sciences     

Contribution of 5-HT1A serotonin receptors of the brain to the regulation of hereditary catalepsy

Selective agonists 5-HT_1A of serotonin receptors (8-OH-DPAT and flezinoxan) had an inhibitory effect on the manifestation of hereditary catalepsy in mice and rats. No differences were revealed in specific binding of³H-8-OH-DPAT to 5-HT_1A receptors in the striatum of either cataleptic or noncataleptic mice and rats. Nonetheless, an increase of the density of these receptors was observed in the frontal cortex of CBA mice predisposed to catalepsy in comparison with mice of the noncataleptic C57Bl strain. The data indicate a contribution of 5-HT_1A receptors to the regulation of hereditary catalepsy. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 118, N ^o 12, pp. 633–635, December, 1994 Presented by V. P. Kaznacheev, Member of the Russian Academy of Medical Sciences     

Modulation of type A K+ current inDrosophila larval muscle by internal Ca2+; effects of the overexpression of frequenin

The calcium-dependent modulation of type A K⁺ current (I _A) has been investigated using a two-electrode voltage clamp on larval muscle cells ofDrosophila. It was found that the amplitude ofI _A increases when [Ca²⁺]₀ is changed from 0.2 mM to 2 mM. The increase inI _A amplitude is not due to overlap with the Ca²⁺-dependent fast K⁺ current,I _CF, since it is observed also inslo ¹ mutants, which are deficient for this current. This effect is not due to Ca²⁺-dependent shifts in the steady-state activation/inactivation kinetics. The phenomenon is probably due to elevations in internal calcium since it is abolished by Ca²⁺ channel blockers and promoted by caffeine (5 mM) if added in the absence of external calcium. This calcium effect was dose-dependent since it was not observed in the presence caffeine plus 2 mM calcium in the bath nor for values of [Ca²⁺]₀ above 4 mM. The Ca²⁺-dependent modulation ofI _A is absent inV7, a mutation that causes overexpression of frequenin, a recoverin-like Ca²⁺-binding protein which stimulates guanylyl cyclase [31]. One possible explanation for the loss ofI _A modulation in theV7 mutation is that the excess of frequenin alters intracellular cGMP-dependent metabolic pathways responsible for the internal calcium homeostasis.     

Disturbances of hypoxanthine metabolism in the liver of resuscitated rats

Catabolism of purine mononucleotides to hypoxanthine and xanthine in the liver is enhanced in rats resuscitated after a 6.5-min asphyxia. Reduced incorporation of¹⁴C-hypoxanthine into these nucleotides 30 min 1, and 3 days after resuscitation attests to its disturbed reutilization. This probably promotes activation of the xanthine oxidase reaction, leading to purine deficit and hyperproduction of reactive oxygen species. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 124, No. 12, pp. 629–631, December, 1997     

cAMP-dependent inward rectifier current in neurons of the rat suprachiasmatic nucleus

Electrophysiological properties of the inward rectification of neurons in the rat suprachiasmatic nucleus (SCN) were examined by using the single-electrode voltage-clamp method, in vitro. Inward rectifier current (I _H) was produced by hyperpolarizing step command potentials to membrane potentials negative to approximately −60 mV in nominally zero-Ca²⁺ Krebs solution containing tetrodotoxin (1 μM), tetraethylammonium (40 mM), Cd²⁺ (500 μM) and 4-aminopyridine (1 mM).I _H developed during the hyperpolarizing step command potential with a duration of up to 5 s showing no inactivation with time.I _H was selectively blocked by extracellular Cs⁺ (1 mM). The activation of the H-channel conductance (G _H) ranged between −55 and −120 mV. TheG _H was 80–150 pS (n=4) at the half-activation voltage of −84±7 mV (n=4). The reversal potential ofI _H obtained by instantaneous current voltage (I/V) relations was −41±6mV (n=4); it shifted to −51±8mV (n=3) in low-Na⁺ (20 mM) solution and to −24±4 mV (n=4) in high-K⁺ (20 mM) solution. Forskolin (1–10 μM) produced an inward current and increased the amplitude ofI _H. Forskolin did not change the half-activation voltage ofG _H. 8-Bromo-adenosine 3′,5′-cyclic monophosphate (8-Br-cAMP, 0.1–1 mM) and dibutyryl-cAMP (0.1–1 mM) enhancedI _H. 3-Isobutyl-1-methylxanthine (IBMX, 1 mM) also enhancedI _H. The results suggest that the inward rectifier cation current is regulated by the basal activity of adenylate cyclase in neurons of the rat SCN.     

Stimulation of the DNA replication and murine bone marrow cell proliferation with exogenous zinc-metallothionein

It is shown that zinc-metallothionein from rat liver increases 1.5-fold thein vitro incorporation of³H-thymidine in murine bone marrow cells. The same concentrations of zinc chloride and a mixture imitating zinc-metallothionein (zinc, cysteine, and albumin) inhibit DNA synthesis. In mice receiving an intraperitoneal injection of zinc-metallothionein 10–15 min before γ-irradiation, the incorporation of³H-thymidine and the content of nucleated cells in the bone marrow is 1.5- to 2-fold higher than those in unprotected animals, the number of endogenous splenic colonies in pretreated mice being 2.7-fold higher. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 122, No. 11, pp. 505–508, November, 1996     

Non-invasive imaging of optical parameters of biological tissues

The normalised back-scattered intensity (NBI) profiles at various locations on the forearms of ten human subjects were obtained by moving the multi-probe of a laser reflectometer. The statistical analysis of the NBI data showed that the variation in the NBI was significantly higher at the ulnar region compared with that at other regions. For determination of the scattering (μ _s ) and absorption (μ _a ) coefficients and the anisotropy parameter g at each location on the forearm, these profiles were matched with the NBI profiles simulated by a Monte Carlo procedure (χ _0.99 ² ). For the reconstruction of images of variation of these parameters, the averaged values ofμ _a ,μ _s and g at all locations on the forearms of the subjects were determined. The absorption coefficient had a minimum (1.92 cm⁻¹) and maximum (2.21 cm⁻¹) at the wrist and the lateral region of the forearm, respectively. The scattering coefficient had a maximum (194 cm⁻¹) at the medial side and near the elbow, and a minimum (186 cm⁻¹) at the lateral side of the forearm. Similar changes in the anisotropy parameter were also observed. By interpolation of the data of each parameter on a 100×100 image matrix and after median filtering, colour-coded images of the variation in the optical parameters were constructed. These images could be useful for diagnostic and therapeutic applications of lasers.     

Functional activity of catecholaminergic system in human fetal midbrain and diencephalon

The development of catecholaminergic system of the midbrain and diencephalon was studied in human embryos and fetuses aged 6, 8, 10, and 12 weeks by specific capture and K⁺-stimulated release of³H-dopaminein vitro. Specific capture of³H-dopamine was first detected in the midbrain of 6-week embryos and in the diencephalon of 8-week fetuses. The time course of the capture points to on-going differentiation of catecholaminergic neurons and fiber growth and the presence of the caudorostral gradient in the development of brain catecholaminergic system. The release of catecholamines was not stimulated in response to membrane depolarization in the midbrain and diencephalon at any of the studied stages of development. The difference in the time of capture and K⁺-stimulated release of catecholamines is related to specific features of differentiation of these neurons in human fetuses. Tranlated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 124, No. 9, pp. 259–262, September, 1997     

Immunological correlation between morphine tolerance and the effect of naloxone in rats of different age

In 3–6-week-old morphine-sensitive rats, in which morphine injection produced an analgetic effect, the serum titer of antimorphine antibodies 24 h postinjection is less than half that observed in morphine-resistant animals. Administration of naloxone to morphine-sensitive rats induces hyperalgesia and considerably raises the serum titer of antimorphine antibodies. Chronic injections of the same dose of morphine, which cause its analgetic effect to disappear, increase the titer of antibodies in morphine-sensitive rats 2-fold. In morphine-resistant rats naloxone produces an analgetic effect followed by its gradual decay and disappearance in the course of chronic administration. Subsequent administration of morphine induces analgesia, raises the titer of antimorphine antibodies, and lowers the titer of antiidiotypic antibodies. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 121, N ^o 1, pp. 67–70, January, 1996 Presented by K. V. Sudakov, Member of the Russian Academy of Medical Sciences     

An experimental model of pseudotuberculosis infection in monkeys

An experimental model of pseudotuberculosis infection was developed usingPapio hamadryas monkeys. Clinical manifestations and some microbiological and immunological aspects of pseudotuberculosis caused by oral infection of animals are studied. The values of LD₅₀ of the pseudotuberculosis agent are established for monkeys, white mice, and guinea pigs. Oral infection of monkeys with sublethal doses ofYersinia pseudotuberculosis is found to induce a pronounced specific immunity. The efficacy of immunoblotting for serologic diagnosis of pseudotuberculosis in clinically obscure cases is demonstrated. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 118, N ^o 7, pp. 59–62, July, 1994     

Specificities of the mechanism of bacterial development during the lag phase

The mechanisms ofE. coli development during the lag phase are described on the basis of biophysical characteristics of the bacterial cell. A bioelectromagnetic model closely approximates the experimental parameters of the time course ofE. coli andE. aerogenes development in the mono- and mixed culture. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 117, N ^o , 3, pp. 331–336, March, 1994 Presented by A. D. Ado, Member of the Russian Academy of Medical Sciences     

Graphic analysis of contraction-distension isotherms for pulmonary surfactant monolayers

A new method for analyzing the surface-active properties of pulmonary surfactants is proposed, based on calculating a “local stability index” and then plotting this index as a function ofS/S _o, whereS _o andS are, respectively, the initial and contracted areas of the surfactant monolayer formed at the interface. The course of the curves thus obtained allows for reasonably precise and easy comparisons of alterations in the surface-active properties of pulmonary surfactants in response to different factors acting on the body. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 120, N ^o 10, pp 370–372, October, 1995 Presented by B. I. Tkachenko, Member of the Russian Academy of Medical Sciences