ENERGETICS OF DNA REPAIR IN UV-IRRADIATED PERIPHERAL BLOOD LEUKOCYTES FROM CHRONIC MYELOID LEUKAEMIA PATIENTS

Abstract— The relationship between energy metabolism and UV-induced (251 nm) DNA repair has been investigated in leukocytes obtained from peripheral blood of chronic myeloid leukaemia patients. Energy supply was modulated by using inhibitors of respiratory (antimvcin-A) and glycolytic (2-deoxy-o-glucose and other glucose analogues) pathways for adenosine-triphosphatc (ATP) production. DNA repair was measured by the unscheduled DNA synthesis technique. Parameters of energy metabolism like glucose utilization. lactate production and ATP content of cells. were measured under similar experimental conditions. The observations made indicate the following results: (1) ATP for DNA repair can be supplied by the respiratory and/or by the glycolytic pathway. (2) In the absence of respiration, the rate of glycolysis bears a linear correlation with DNA repair. (3) A minimum threshold rate of ATP-production is necessary for DNA repair.     

Generation and cycloaddition reactions of indole-2,3-quinodimethanes

N-methyl and N-tert-butoxycarbonylindole-2,3-quinodimethanes ($\text{2}$ and $\text{3}$) have been generated and observed to undergo intermolecular cycloaddition reactions with dienophiles.     

The determination of rubidium by the method of stable isotope dilution

The rubidium contents of a granite (G-1), a diabase (W-1) and sea-water have been determined by mass spectrometric isotope dilution analysis. The values found are: G-1, 214 p.p.m-; W-1, 21.3 p.p.m.; sea water, 121.4 μg/l. These results show excellent agreement with values obtained at Harwell by neutron activation analysis, and the coefficient of variation for four determinations is usually ±1–2%.Rubidium ions were produced in the mass spectrometer by either a side filament or a centre filament technique. The former method enables rubidium and lithium determinations to be combined; the results obtained by the second method suggest that concentrations of the order of 1 p.p.m. may be determined for a sample of only a few mg with little chemical treatment beyond that required to decompose the sample.     

A critical comparison of computer programs for the potentiometric determination of stability constants

The performance of five of the best-known computer programs LETAGROP, SCOGS, MINIQUAD, SUPERQUAD and ESTA, is critically discussed. All these programs are based on least-squares refinement procedures but differ in some important aspects: (a) the definition of the residuals function; (b) the minimization procedure; (c) the statistical and weighting parameters. Each of these aspects is evaluated and the programs are compared on this basis.     

Semiautomatic and automatic catalytic amperometric and catalytic constant-current potentiometric titrations of gold(III)

Semiautomatic and automatic amperometry and constant-current potentiometry were used to follow the course of catalytic titration of gold(III) with potassium iodide. The Ce(IV)-As(III) system in the presence of sulfuric acid was used as the indicator reaction. The possibilities of the application of two types of graphite electrodes were investigated. The effect of concentration of the indicator reaction components, and the presence of organic solvents and acids on the shape of the catalytic titration curves was studied. Amounts of 80–900 μg of gold(III) were determined with a relative standard deviation less than 1.1%. The results obtained are in good agreement with those of comparable methods.     

PHOTOVOLTAIC ACTION SPECTRA AND EFFICIENCIES OF CHLOROPHYLL a SPECIES ABSORBING NEAR 700 nm

Abstract— Alcohol vapors affect the photovoltaic properties of anhydrous chlorophyll a (Chi a). At 23°C, a photovoltaic cell of the type Allanhydrous Chi a|Ag has been successively submitted to non saturating vapors of methanol, ethanol, 1-propanol, 2-propanol, cyclopropyl carbinol, cyclopentanol, methyl cyclopropyl carbinol, 1-butanol, 1-pentanol and chloroethanol. The action spectrum of anhydrous Chi a has a maximum in the red at 672 nm. This maximum is shifted towards 700 nm under the influence of alcohol vapors. The most important changes occur for ethanol, 1-propanol and 2-propanol. In the same way, the conversion efficiencies of light energy into electrical energy, measured at the maximum in the red are, for the same alcohols, higher than the initial value 1.7 times 10^-2% obtained on the average for anhydrous Chi a. A maximum value of 6.3 times 10^-2% has been obtained after rehydration of Chi a solvated with 2-propanol. The influence of alcohol vapors has been interpreted in terms of microcapillarity of anhydrous Chi a and a mean microcavity radius of 11 ± 6 Å has been deduced from the photocurrent variation with the amount of alcohol vapor present in the measuring area. Furthermore, the action spectrum shift towards 700 nm has been interpreted by the formation, at 23°C, of Chi a special aggregates whose action spectrum has been obtained by difference. Infrared spectroscopy demonstrated that anhydrous Chi a obtained from electrodeposition is an assembly of Chi a dimers and that alcohol vapors, producing the special aggregates formation at 23°C, induce a decrease of the free C=O ketone band and an increase of the associated C=O ketone. The C=O esters band is not affected by the Chi a reorganization.     

A comparison of phototautomerism in different sites of free-base porphin (H2P) in n-alkane crystals

Selective laser-induced phototautomerism of free-base porphin in different n-alkanes (n-hexane, n-heptane, n-octane, nnonane, n-decane, n-undecane and n-dodecane) has been used to identify tautomer splittings in a number of sites in polycrystalline samples at 2 K. Pairs or lines arising from the two molecular orientations in each site can be reversibly transformed into each other. In the odd n-alkanes the occupation of different sites was not dependent on the rate at which the samples were frozen, but in the even n-alkanes metastable sites were only occupied following rapid quenching.     

13C NMR studies of molecular relaxation processes in polar fluids

A study of the dynamical molecular structure of a dilute polar fluid is reported, in which ¹³C spin-lattice relaxation times of decanol in deuterated cyclohexane are presented for the individual carbon atoms, and the results are discussed in the context of viscosity data of decanol in alkane systems. The two techniques provide complementary information about the mobility of the alcohol chains and the onset of multimer formation, which is also pertinent to the dynamics of electron solvation in the same systems.     

Investigations in the imidazole series 97. Synthesis and some transformations of 5-nitro-5-hydroxyalkylamino- and 4-hydroxy-alkylamino-5-nitroimidazoles

A series of 1-alkyl(1,2-dialkyl)-substituted 4-nitro-5-hydroxyalkylamino- and 4-hydroxyalkylamino-5-nitro-imidazoles were obtained by the reaction of 1-alkyl(1,2-dialkyl)-substituted 4-nitro-5-chloro(bromo)imidazoles with amino alcohols. Their reactions with thionyl chloride and carboxylic acid halides and their catalytic hydrogenation were studied. For Communication 96, see [1]. Center of the Chemistry of Medicinal Agents, All-Russia Scientific-Research Chemical-Pharmaceutical Institute, Moscow 119815. Novokuznetsk Scientific-Research Chemical-Pharmaceutical Institute, Novokuznets 654034, Russia. Zaporozh'e State Medical University, Zaporozh'e 33074. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10. pp. 1346–1351, October, 1998.