Sugar-dependent aggregation of glycoconjugated chlorins and its effect on photocytotoxicity in HeLa cells

In order to explore the influence of the sugar moieties of glycoconjugated chlorins on the photocytotoxicity, we studied the photochemical properties of four glycoconjugated chlorins in aqueous media such as cytoplasm and the concentration dependence of photocytotoxicity in HeLa cells. In phosphate-buffered saline, the fluorescence intensities of 5,10,15,20-tetrakis[3-(beta-D-glucopyranosyloxy)phenyl]chlorin (m-1a) and 5,10,15,20-tetrakis[3-(beta-D-galactopyranosyloxy)phenyl]chlorin (m-1b), i.e., chlorins having hexose groups, were about 2-fold greater than those of 5,10,15,20-tetrakis[3-(beta-d-xylopyranosyloxy)phenyl]chlorin (m-1c) and 5,10,15,20-tetrakis[3-(beta-d-arabinopyranosyloxy)phenyl]chlorin (m-1d), i.e., chlorins having pentose groups, owing to a sugar-dependent difference of aggregation behavior. While no cytotoxicity was found in the dark, the highest photocytotoxicity was shown by m-1a (82% inhibition) in HeLa cells. This was higher than those of m-1b, m-1c, m-1d and tetraphenylporphyrin tetrasulfonic acid. The glycoconjugated chlorins except for m-1b appeared to be distributed diffusely throughout the cytoplasm. Among the four photosensitizers, m-1a showed the highest intensity in confocal fluorescence images, in agreement with the in vitro photocytotoxicity results. For m-1c, no photocytotoxicity was found at drug concentrations from 0.2 to 0.04 microM. Hence, sugar-dependent aggregation is not the major reason for the unexpected lack of efficacy of m-1c, which is uptaken efficiently by HeLa cells. For the glycoconjugated chlorins, these results suggest the biological aspects of sugar moiety play much crucial role rather than chemical aspects.     

Spatiotemporal alteration of phospholipids and prostaglandins in a rat model of spinal cord injury

We determined quantitative and qualitative alterations in lipids during the occurrence and progression of spinal cord injury (SCI) in rats to identify potential clinical indicators of SCI pathology. Imaging mass spectrometry (IMS) was used to visualize twelve molecular species of phosphatidylcholine (PC) on thin slices of spinal cord with SCI. In addition, twelve species of phospholipids and five species of prostaglandins (PGs) were quantified by liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) of lipid extracts from control/injured spinal cords. Unique distribution patterns were observed for phospholipids with different fatty acid compositions, and distinct dynamic changes were seen in both their amounts and their distributions in tissue as tissue damage resulting from SCI progressed. In particular, PCs containing docosahexaenoic acid localized to the large nucleus in the anterior horn region at one day post-SCI and rapidly decreased thereafter. In contrast, PCs containing arachidonic acid (AA-PCs) were normally found in the posterior horn region and were intensely and temporarily elevated one week after SCI. Lysophosphatidylcholines (LPCs) also increased at the same SCI stage and in regions with elevated AA-PCs, indicating the release of AA and the production of PGs. Moreover, LC-ESI-MS/MS analysis of lipid extracts from the spinal cord tissue at the impact site demonstrated a peak in PGE2 that reflected the elevation/reduction pattern of AA-PCs and LPC. Although further investigation is required, we suggest that invasive immune cells that penetrated from the impaired blood-brain barrier at 1-2 weeks post-SCI may have produced LPCs, released AA from AA-PCs, and produced PGs in SCI tissue at sites enriched in AA-PCs/LPC.     

Formation of octacalcium phosphates with co-incorporated succinate and suberate ions

Octacalcium phosphates (OCPs) co-incorporated with various molar ratios of succinate and suberate ions were synthesized by wet processing. The interplanar spacings of the (100) planes (d(100)) of OCPs formed in the presence of succinic acid (Suc) or suberic acid (Sub) were larger than those of OCPs formed without addition of a dicarboxylic acid to the reaction solvent. The increases in the interplanar spacings of the (100) planes were caused by substitution of HPO(4)(2-) by dicarboxylate ions. The OCPs with co-incorporated succinate and suberate ions, i.e. solid solutions of OCP with incorporated Suc and Sub, were formed by reactions in the presence of Suc and Sub. When the Suc/(Suc + Sub) values in the starting compositions were in the range 0.45-1.0, Suc was preferentially incorporated into the OCP. In contrast, when the Sub/(Suc + Sub) values in the starting compositions were in the range 0.60-1.0, Sub was preferentially incorporated into the OCP crystals.     

DNA-bleomycin interaction: Nucleotide sequence-specific binding and cleavage of DNA by bleomycin

Biosynthetic intermediates and synthetic analogues of bleomycin (BLM) have been investigated for their metal binding, dioxygen activation, and DNA cleavage. Molecular O₂ was activated by the Fe(II) complex of a synthetic model ligand. Nucleotide sequence specificities in DNA cleavage by the BLM-Fe(II) and deglyco-BLM-Fe(II) complexes were almost identical. It has been shown that (1) the β-aminoalanine-pyrimidine-β-hydroxyhistidine portion of BLM is essential for the metal binding and dioxygen activation and (2) the bithiazole moiety contributes to the specific binding to guanine base of DNA.     

A verified method for bounding clusters of zeros of analytic functions

In this paper, we propose a verified method for bounding clusters of zeros of analytic functions. Our method gives a disk that contains a cluster of m   zeros of an analytic function f(z)$f(z)$. Complex circular arithmetic is used to perform a validated computation of n  -degree Taylor polynomial p(z)$p(z)$ of f(z)$f(z)$. Some well known formulae for bounding zeros of a polynomial are used to compute a disk containing a cluster of zeros of p(z)$p(z)$. A validated computation of an upper bound for Taylor remainder series of f(z)$f(z)$ and a lower bound of p(z)$p(z)$ on a circle are performed. Based on these results, Rouché's theorem is used to verify that the disk contains the cluster of zeros of f(z)$f(z)$. This method is efficient in computation of the initial disk of a method for finding validated polynomial factor of an analytic function. Numerical examples are presented to illustrate the efficiency of the proposed method.