Effects of inorganic and organic lead compounds on chromosomal length in human lymphocytes

In vitro exposure of human lymphocyte cultures to spindle inhibitors reduce the average chromosome length^1,2. In this report chromosome length measurements were used for indirect but quantitative evaluation of the effects of inorganic and organic lead compounds on spindle function. The data indicate that organic compounds are much more powerful spindle inhibitors than inorganic lead compounds, almost as potent as colchicine. Occupational exposure to organic lead compounds may result in partial spindle inhibition, leading to a high probability of nondisjunction.     

Small molecules that induce cardiomyogenesis in embryonic stem cells

A phenotypic cell-based screen of a large combinatorial chemical library led to the identification of a class of diaminopyrimidine compounds (cardiogenol A-D) which can selectively and efficiently induce mouse embryonic stem cells (ESCs) to differentiate into cardiomyocytes. ESC-derived cardiomyocytes were shown to express multiple cardiac muscle markers, including myosin heavy chain, GATA-4, MEF2, and Nkx2.5, and spontaneously form beating regions. Such small molecules will serve as useful chemical probes to study cardiac muscle differentiation and may ultimately facilitate the therapeutic application of ESCs for cardiac repair.     

Estimation of aqueous solubility for a diverse set of organic compounds based on molecular topology

An accurate and generally applicable method for estimating aqueous solubilities for a diverse set of 1297 organic compounds based on multilinear regression and artificial neural network modeling was developed. Molecular connectivity, shape, and atom-type electrotopological state (E-state) indices were used as structural parameters. The data set was divided into a training set of 884 compounds and a randomly chosen test set of 413 compounds. The structural parameters in a 30-12-1 artificial neural network included 24 atom-type E-state indices and six other topological indices, and for the test set, a predictive r2 = 0.92 and s = 0.60 were achieved. With the same parameters the statistics in the multilinear regression were r2 = 0.88 and s = 0.71, respectively.     

Photosensitization of Chinese hamster cells by water-soluble phthalocyanines

Abstract— Phthalocyanines are efficient photosensitizers of cultured mammalian cells and are considered for use in photodynamic therapy. The photobiological properties of chloroaluminum phthalocyanine sulfonate (AIPCS) were compared to those of the unsubstituted, water-insoluble derivative (AIPC). The development of photosensitization after addition of the dye into growth medium is ca. 8 times more rapid for AlPC than for AIPCS. Conversely, the loss of photosensitization when cells are incubated in a dye-free growth medium following a period of dye uptake, is also faster for AIPC. The dye uptake followed a kinetic behavior similar to the development of photosensitivity, but the loss of dye was too slow for both AlPC and AIPCS to explain loss of photosensitivity. When cells are incubated prior to illumination with AIPCS in phosphate buffered saline instead of growth medium, shorter time and smaller amount of dye are required to achieve the same level of photosensitization. The dependence of photosensitivity on dye concentration is linear for both AIPC and AIPCS. As already found for AIPC, photosensitization by the water-soluble derivative is also not enhanced in D₂O, suggesting that singlet oxygen is not involved in the cytotoxic response. Sodium salicylate, which was found to enhance the effect of AlPC was also effective with AIPCS. This effect is quite specific since the meta and para isomers had no effect. The metal atom complexed with the phthalocyanine ring is significant for the photobiological activity. Among the compounds tested, those containing Al or Zn are most active.     

Classification of IR spectra of organic compounds by the methods of multidimensional statistics

In order to clarify the possibilities of classifying the IR spectra of organic compounds by methods of multidimensional statistics, with the object of casting further light on the relationship between the structure of a compound and noncharacteristic spectral criteria, an experiment was carried out, in which methods of factor analysis were applied to the entire set of spectra. A clusterization was obtained of the original spectra conforming with the chemical classification of the compounds studied and universal vectors for transition into a low-dimensionality space, where the spectra studied are described by 11 factors instead of the initial 65. The concept of spatial identification of the spectra is discussed.K. A. Timiryazev Agricultural Academy. Translated from Zhurnal Strukturnoi Khimii, Vol. 34, No. 1, pp. 94–100, January–February, 1993.     

Resistance to induction of micronuclei,chromosomal aberrations and apoptosis by <Superscript>60</Superscript>Co gamma-ray in a cell strain M5, derived from Chinese hamster V79 cells

The paper aims to investigate cytogenetic and apoptotic responses of γ-irradiation in a radio-resistant cell strain designated as M5. Induced micronuclei, chromosomal aberrations, nuclear fragmentation and nucleosomal ladders by γ-irradiation were less at equal doses in M5 cells in comparison with that obtained in the parental Chinese hamster V79 cells. However, at equal survival, there were no differences in the end points studied. Results indicate that the residual damages that lead to reproductive cell death also resulted in the cytogenetic and apoptotic responses. We speculate that the repair efficiency in M5 cells was more efficient and increased DNA repair could be the cause of radiation resistance observed in M5 cells.     

Classification of organic nitrogen -containing compounds based on the electronic structure of their molecules

Conclusions It was shown that it is theoretically possible to classify nitrogen-containing compounds on the basis of the obtained quantum-chemical data concerning their electronic structure.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2611–2613, November, 1982.     

Anthracene based organic dipolar compounds for sensitized solar cells

Organic dyes that consist of an anthracene moiety between a triphenylamine donor group and a cyanoacrylic acid acceptor group displayed remarkable solar-to-energy conversion efficiency in dye-sensitized solar cells. The planar geometry of anthracene and its bulky substituents helped the dyes to form a high quality monolayer on the surface of TiO₂. A typical device made with the dye AN-Bu displayed a maximal photon-to-current conversion efficiency (IPCE) 65% in the region of 350–510 nm, a short-circuit photocurrent density (J_sc) 12.78 mA cm⁻², an open-circuit photovoltage (V_oc) 0.73 V, and a fill factor (FF) 0.67, corresponding to an overall conversion efficiency 6.23%. In an experiment of using deoxycholic acid (DCA) as a co-absorbent, the values of V_oc stayed in a similar range, yet the values of J_sc were reduced in ca. 11% due to a decrease of loading amounts. This result indicated that the quality of the dye films cannot be further improved by the adding of DCA. The photophysical properties were analyzed with the aid of a time-dependent density functional theory (TDDFT) model with the B3LYP functional.     

Performance of (consensus) kNN QSAR for predicting estrogenic activity in a large diverse set of organic compounds

A novel method (in the context of quantitative structure–activity relationship (QSAR)) based on the k nearest neighbour (kNN) principle, has recently been introduced for the derivation of predictive structure–activity relationships. Its performance has been tested for estimating the estrogen binding affinity of a diverse set of 142 organic molecules. Highly predictive models have been obtained. Moreover, it has been demonstrated that consensus-type kNN QSAR models, derived from the arithmetic mean of individual QSAR models were statistically robust and provided more accurate predictions than the great majority of the individual QSAR models. Finally, the consensus QSAR method was tested with 3D QSAR and log?P data from a widely used steroid benchmark data set.     

Performance of (consensus) kNN QSAR for predicting estrogenic activity in a large diverse set of organic compounds

A novel method (in the context of quantitative structure-activity relationship (QSAR)) based on the k nearest neighbour (kNN) principle, has recently been introduced for the derivation of predictive structure-activity relationships. Its performance has been tested for estimating the estrogen binding affinity of a diverse set of 142 organic molecules. Highly predictive models have been obtained. Moreover, it has been demonstrated that consensus-type kNN QSAR models, derived from the arithmetic mean of individual QSAR models were statistically robust and provided more accurate predictions than the great majority of the individual QSAR models. Finally, the consensus QSAR method was tested with 3D QSAR and log P data from a widely used steroid benchmark data set.     

Recovery of Chinese hamster cells following photosensitization by zinc tetrahydroxyphthalocyanine

The phthalocyanine dyes are attractive sensitizers for photodynamic therapy of cancer. The light fluence response curves for photocytotoxicity of zinc tetrahydroxyphthalocyanine were constructed using the colony-forming ability of Chinese hamster cells as an end-point. The survival curve of cells photosensitized to white light by this dye has a pronounced shoulder followed by an exponential decline. Postillumination hypertonic treatment (0.5 M NaCl for 20 min at 37 degrees C) enhanced log-phase killing, although to a lesser extent than after exposure to ionizing radiation. While such an enhancement usually indicates that the cells are able to repair potentially lethal damage, delayed trypsinization of photosensitized cells in plateau-phase failed to show a significant increase in cell survival. Thus, the repair of such a damage in plateau-phase is apparently absent. Experiments with split light fluence indicated that log-phase cells can repair sublethal damage during a 24 h interval, as evidenced by the reappearance of the shoulder on the split-dose survival curve.     

Repair replication in Chinese hamster cells after damage from ultraviolet light

Abstract— After irradiation with u.v. light, Chinese hamster cells perform repair replication of their DNA. Small numbers of nucleosides are inserted into DNA, such that when BrUdR is used there is no detectable change in density. Repair replication begins immediately after irradiation, but it decelerates steadily and at least half is complete within 4 hr. Repair replication saturates above 200 ergs/mm² at a level which represents 0.055 per cent replacement of all thymine sites in 4 hr. Repair replication in mammalian cells, in contrast to that in microorganisms, does not appear to replace pyrimidine dimers excised from DNA in acid soluble form, and neither repair nor semiconservative replication discriminates between BrUdR and TdR.     

Oxidation of organic compounds

It has been established that the main products of the oxidative ammonolysis of tris(hydroxymethyl)-4-picoline are isonicotinic acid and its amide and nitrile. At a molar ratio of the starting material to oxygen (in the form of air) to ammonia to water to 1 80–90 12–30 125–150 and with a contact time of 0.12–0.20 sec, these compounds can be obtained with yields of, respectively, 25–30, 5–10, and 45–50% of those theoretically possible on the basis of the raw material fed.For part LIII, see [1].     

Determination of nitrogen in organic compounds

Summary A simplified method is described for the electrolytic generation of oxygen for use in the micro-Dumas determination of nitrogen. A flowmeter with an adjustable range is also described.

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Zusammenfassung Eine vereinfachte Anordnung zur elektrolytischen Sauerstoffentwicklung für die Verbrennung stickstoffhältiger Substanzen nach dem MikroDumas-Verfahren in einer Kohlendioxyd-Sauerstoff-Atmosphäre wird angegeben. Außerdem wird ein justierbarer Strömungsmesser beschrieben.

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Résumé On décrit une méthode simplifiée pour la production électrolytique de l'oxygène utilisé dans le microdosage de l'azote suivantDumas. On décrit aussi un fluxmètre à échelle réglable.