Photodynamic activity of chlorin e6 and chlorin e6 ethylenediamide in vitro and in vivo.

Several parameters of chlorin e6 and its derivative chlorin e6 ethylenediamide have been investigated as these compound are potential sensitizers for photodynamic therapy. A study carried out to compare the cellular uptake of the pigments indicates that chlorin e6 ethylenediamide possesses an enhanced affinity for tumour cells and cellular membranes. Comparison of the uptake in induced sarcoma shows that chlorin e6 ethylenediamide is a much better tumour localizer than chlorin e6. The efficiency of phototherapy with chlorin e6 ethylenediamide is higher than that with chlorin e6. These data show the influence of the substitution of the carboxyl groups in chlorin e6 by ester and amide groups on the photosensitizing properties of the pigments.     

Assessment of the In Vivo Release and Biocompatibility of Novel Vesicles Containing Zinc in Rats

This paper is focused on the in vivo release and biocompatibility evaluation in rats of some novel systems entrapping zinc chloride in lipid vesicles. The particles were prepared by zinc chloride immobilization inside lipid vesicles made using phosphatidylcholine, stabilized with 0.5% chitosan solution, and dialyzed for 10 h to achieve a neutral pH. The submicrometric systems were physico-chemically characterized. White Wistar rats, assigned into four groups of six animals each, were treated orally with a single dose, as follows: Group I (control): deionized water 0.3 mL/100 g body weight; Group II (Zn): 2 mg/kg body weight (kbw) zinc chloride; Group III (LV-Zn): 2 mg/kbw zinc chloride in vesicles; Group IV (LVC-Zn): 2 mg/kbw zinc chloride in vesicles stabilized with chitosan. Haematological, biochemical, and immune parameters were assessed after 24 h and 7 days, and then liver fragments were collected for histopathological examination. The use of zinc submicrometric particles—especially those stabilized with chitosan—showed a delayed zinc release in rats. No substantial changes to blood parameters, plasma biochemical tests, serum complement activity, or peripheral neutrophils phagocytic capacity were noted; moreover, the tested substances did not induce liver architectural disturbances. The obtained systems provided a delayed release of zinc, and showed good biocompatibility in rats.     

Resonance raman spectra of π-anions of Zn-porphyrins

Institute of Molecular and Atomic Physics Academy of Sciences of Belarus, 70, F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 62, No. 2, pp. 128–136, March–April, 1995.     

Effect of low radiation doses on the content of endogeneous porphyrins in the living organism

Investigations of urinary excretion of copro- and uroporphyrins from the organism of healthy humans and humans exposed to low radiation doses (children and adolescents, adults and pregnant females) have been performed with the use of the high-sensitivity fluorescence method of determination of endogeneous porphyrins in the living organism. The ranges of the most probable concentrations of copro- and uroporphyrins in the morning portion of urine were determined for three control groups of healthy humans and six test groups of humans exposed to low radiation doses. It was established that the concentration of endogeneous porphyrins excreted from the organism of adults subjected to the action of ionizing radiation is significantly decreased as compared with the norm and that living for a long time in radionuclidecontaminated territories leads to steady disturbances of porplyrin excretion from the organism. It was also established that the concentration of endogenous porphyrins excreted from the organism of children and adults evacuated from the radionuclide-contaminated zone is significantly increased as compared with the norm. Reported at the VIIIth International Conference on Spectroscopy of Porphyrins and Their Analogs, Minsk, September 22–26, 1998. Institute of Molecular and Atomic Physics, National Academy of Sciences of Belaus, 70, F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 4, pp. 545–548, July–August, 1999.     

Impedance Study of GaN and InGaN Semiconductor Anion Selective Electrodes

The response of potentiometric anion selective electrodes employing undoped GaN or In_0.2Ga_0.8N films as sensing element to detect various anions was investigated in solutions of KF, KNO₃, KCl, HOC₆H₄COONa, KSCN, CH₃COOK, KClO₄ and KBr salts. The calibration plots for the GaN and In_0.2Ga_0.8N semiconductor electrodes contained linear regions extending over four decades of activity change in most solutions. The structure of the GaN and In_0.2Ga_0.8N semiconductor electrode/ electrolyte interface was studied through electrochemical impedance spectroscopy. Analogous equivalent circuits modeling the GaN or In_0.2Ga_0.8N electrode/electrolyte interface were proposed and their parameters were calculated. The space charge layer of the GaN and In_0.2Ga_0.8N semiconductors dominated the impedance of the electrochemical system at high frequencies (>10 kHz), whereas at low frequencies (<10 kHz), the impedance was controlled by the diffusion of electroactive species across the layer of adsorbed ions at the surface of the electrode. Results imply a strong dependence of the electrodes performance on the adsorption capacity of tested anions.     

Luminescence studies of porphyrin exchange in pregnant females

Results of investigations of the level of proto- and coporphyrins in erythrocytes and excretion of coproto- and uroporphyrins from the organism for two control groups are presented. The first group consisted of healthy males and females 20–33 years of age; the second group was consisted of females with nonpathological pregnancy. Levels of proto- and coporphyrins in erythrocytes and copro- and uroporphyrins in urine are investigated. A reliable (P<0.03) increase in the protoporphyrin concentration in erythrocytes of pregnant females compared to the first control group is found. The average protoporphyrin levels in the first and second groups are 344±18 and 488±20 μg/liter, respectively. Coporphyrin levels in these groups differ insignificantly. Coporphyrin excretion from the organism of pregnant females has shown a tendency to increase for pregnancy terms of up to eight weeks and decrease for long terms (more than 32 weeks). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 5, pp. 633–636, September–October, 1997.     

Determination of the content of endogenic porphyrins in children and adolescents with thyroid pathology

The aim of the present work was to use the fluorescence method for elucidating the laws governing porphyrin exchange in children with thyroid pathology to estimate the possibility of creating in future nontradiational approaches to the diagnosis of oncologic diseases. A systematic investigation of the level of photo- and coproporphyrins in the erythrocytes of children and adolescents of from 8 to 17 years old with thyroid pathology (cancer, ganglia, autoimmune thyroiditis) is carried out. A control group of the same ages was examined for comparison. It is shown than in all of the pathologies considered one observes an individual character of porphyrin variation, which affects the content of protoporphyrin and corproporphyrin in erythrocytes. A decrease in the level of endogenic porphyrins in the blood of children with malignant tumors is discovered. Institute of Molecular and Atomic Physics of the Academy of Sciences of Belarus, 70, Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 6, pp. 748–752, November–December, 1997.     

Evaluation of GaN and In0.2Ga0.8N Semiconductors as Potentiometric Anion Selective Electrodes

The response of potentiometric anion selective electrodes consisting of undoped GaN or In_0.2Ga_0.8N films grown on Al₂O₃ (sapphire) was measured in electrolyte solutions of F^?, NO₃^?, Cl^?, SCN^?, ClO₄^? or Br^? anions at concentrations ranging from 10^?6 to 10^?1 M. The slope of the linear regions varied between ?32.8 and ?51.9 mV/decade for the GaN electrode and between ?31.0 and ?72.0 mV/decade for the In_0.2Ga_0.8N electrode. The drift of the GaN electrode reached 1.57 mV/day in KNO₃ solutions, whereas the drift of the In_0.2Ga_0.8N electrode could not be evaluated due to large drops in the slope of its linear range over time. Both electrodes were sensitive to pH variations over the pH range from 12.8 to 1.3. The GaN electrode surface could be electrochemically etched under anodic polarization; however, both GaN and In_0.2Ga_0.8N electrodes remained chemically stable and mechanically intact under open circuit conditions even after prolonged use.