Conjugates of methionine γ-lyase with polysialic acid: Two approaches to antitumor therapy.

The methionine dependence is a well known phenomenon in metabolism of cancer cells. Methionine γ-lyase (EC 4.4.1.11, MGL) catalyzes the γ-elimination reaction of L-methionine and thus could effectively inhibit the growth of malignant cells. Recently we have demonstrated that the mutant form of the enzyme C115H MGL can be used as a component of the pharmacological pair enzyme/S-(allyl/alkyl)-L-cysteine sulfoxides to yield thiosulfinates in situ. Thiosulfinates were shown to be toxic to various cancer cell lines. Therefore the application of the enzyme in enzyme pro-drug therapy may be promising. The conjugates of MGL and C115H MGL with polysialic acid were obtained and their kinetic and pharmacokinetic parameters were determined. The formation of polysialic shell around the enzyme was confirmed by atomic force microscopy. The half-life of conjugated enzymes increased 3-6 times compared to the native enzyme. The cytotoxic effect of conjugated MGL against methionine dependent cancer cell lines was increased two times compared to the values for the native enzymes. The anticancer efficiency of thiosulfinates produced by pharmacological pair C115H MGL/S-(allyl/alkyl)-L-cysteine sulfoxides was demonstrated in vitro. The results indicate that the conjugates of MGL with polysialic acid could be new antitumor drugs.

Effect of cadmium sulfide quantum dots on physical properties of R-phycoerythrin as a protein matrix.

The synthesis and analysis of nanostructures in the cavities of protein molecules is a promising research field in the industry of nanosystems. In this study, atomic force microscopy (AFM) has been used to evaluate the properties of CdS quantum dots synthesized in the tunnel cavities of R-phycoerythrin, a 290 kDa water-soluble pigment protein responsible for light harvesting in red algae. It has been shown that R-phycoerythrin dissolved in deionized water to a concentration of 50 µg/ml is prone to self-organization into regular spatial structures upon adsorption on the surface of mica, but no such structuring takes place in films prepared from R-phycoerythrin solutions diluted tenfold. In the latter case, protein molecules are deformed, as judged from the analysis of the surface profile. R-phycoerythrin with CdS quantum dots in protein cavities (the concentration of the preparation was (48 µg/ml) loses the self-organization ability and is not deformed upon adsorption on the mica surface. Analysis of AFM images by flicker-noise spectroscopy has shown that incorporation of CdS quantum dots into R-phycoerythrin molecules provides for "smoothing" of the protein surface, with various irregularities being leveled off. Conversely, the irregularity of the protein surface increases when R-phycoerythrin molecules are arranged into three-dimensional branching structures. It is concluded that CdS quantum dots interfere with protein-protein interactions and restrain the conformational mobility of the protein. The anomalously rigid structure of R-phycoerythrin in the presence of CdS is due to its conformational rearrangements during the synthesis of quantum dot.

Porphyrin effect on the surface morphology of amphiphilic polymers as observed by atomic force microscopy.

Complexes of porphyrin photosensitizers (PPS) with triblock copolymers of ethylene- and propylene oxide - Pluronics(®) - exhibit markedly increased activity in the generation of singlet oxygen in aqueous media, as compared to pure porphyrins. Pluronics are amphiphilic polymers with surfactant properties suitable for a number of medical applications. PPS-Pluronic systems are considered as promising agents for photodynamic therapy which implies generation of singlet oxygen in the water-based human tissue. Importantly, Pluronics are capable of solubilization of not only water-soluble, but also hydrophobic PPS providing their transfer into the aqueous phase. It has been shown earlier that specific interactions of PPS with Pluronics must play a primary role for the photocatalytic properties of PPS-Pluronic systems. In the process of solubilization of a hydrophobic porphyrin by a Pluronic, both components are dissolved in an organic solvent, which is then removed, and the dry film is re-dissolved in water. Apparently, the initial binding between the porphyrin and the lipophilic part of the polymer takes place already at the stage of the film formation. We applied atomic force microscopy (AFM) to visualize structures formed by Pluronics upon their interactions with meso-tetraphenylporphyrin (TPP). We studied the surface structure of Pluronics(®) F87, F108 and F127 crystallized alone or together with TPP on silicon substrates from chloroform solutions. We found Pluronics to form similar dendritic structures independently of their molecular weight and degree of hydrophobicity. In the presence of TPP, though, we observed formation of distinct convex structures on top of the Pluronic dendrites. These structures appeared to consist of multiple flat layers placed on top of each other. Their sizes varied among the three Pluronics. We believe that TPP aggregates interact with the hydrophobic units of Pluronics causing the polymer chains to pack themselves in a distinct manner around those TPP-containing "cores". These interactions apparently direct formation of complexes between the porphyrin and the polymer upon their dissolution in water, thus resulting in the encapsulation of TPP aggregates inside a Pluronic micelle. A single mechanism for the TPP solubilization by Pluronics is consistent with the same catalytic activity of the three TPP-Pluronic systems observed in the photooxidation of tryptophan.

Results of the first randomized multicentre trial on childhood acute lymphoblastic leukaemia in Russia.

Until 1990, the survival of children with acute lymphoblastic leukaemia (ALL) in Russia was below 10%. To establish a protocol feasible under conditions there, ALL-MB 91 was designed to avoid prolonged bone marrow aplasia, thereby reducing needs for extensive supportive care, blood transfusions, long-lasting hospitalization and costs. High-dose therapies were avoided, anthracycline use was limited and CNS radiation therapy only foreseen in high-risk patients (about 30%). This was randomized against a modified BFM protocol. From 1995 to 2002, 834 patients of age up to 18 years were registered in 10 centres and 713 received after central randomization the allocated risk-stratified treatment. After a median follow-up of 7 years, the event-free survival (EFS) was 67+/-3% on ALL-MB 91 (N=358) vs 68+/-3% on ALL-BFM 90m (N=355). The overall survival (OS) was 71+/-3% vs 74+/-2%, respectively. Anaemia, thrombocytopenia, agranulocytosis >10 days and hospitalization (median 35 vs 68 days) were lower on ALL-MB 91 (P<0.01, N=197). While EFS and OS were similar with both protocols, ALL-MB 91 significantly incurred fewer toxicity and resource requirements and, therefore, has been increasingly used across Russia.

[The results of a multicenter trial of acute lymphoblastic leukemia treatment on ALL-MB 91/ALL-BFM 90m in children: analysis of efficacy and toxicity].

AIM: A comparative analysis of efficacy and toxicity of two chemotherapy regimens: standard German protocol ALL-BFM 90m and less intensive original test protocol ALL-MB 91 in a multicenter trial of acute lymphoblastic leukemia (ALL) in children. MATERIAL AND METHODS: In 1995-2002 a total of 834 patients with newly diagnosed ALL aged 0-18 years were admitted to 10 clinics of Russia. Of them, 713 were randomized in two groups: treatment program ALL-BFM 90m (n = 355) and ALL-MB 91 program (n = 358). RESULTS: In 7-year follow-up median, 10-year event-free survival (EFS) and overall survival (OS) did not differ significantly between the groups and was 67 +/- 3 and 68 +/- 3% (ALL-MB 91) and 74 +/- 2, 71 +/- 3% (ALL-BFM 90m), respectively. Though the rate of isolated recurrences in CNS in patients on the protocol ALL-MB 91 was 2.8%, they developed only in 0.8% patients of the standard risk group. Anemia, thrombocytopenia and agranulocytosis developed less frequently, hospital stay was significantly shorter on the test protocol vs the control one (p < 0.01). CONCLUSION: EFS and OS on the test (ALL-MB 91) and control (ALL-BFM 90m) protocols were equivalent in lower toxicity and cost of therapy.

[Results of the treatment of childhood acute lymphoblastic leukemia according to the Berlin-Moscow-91 protocol in 1991-2000]. / Rezul'taty lecheniia ostrogo limfoblastnogo leikoza u detei po protokolu Moskva-Berlin-91 v 1991-2000 gg.

The report deals with the results of application of an original protocol--the Berlin-Moscow-91 (BM-91)--for the treatment of acute lymphoblastic leukemia (ALL) in children. The researchers' major concern was to improve survival and cut down side-effects incidence as well as to prevent and successfully manage occult neuroleukemia as a potential source of relapse. Patients aged 5 months-15 years received the BM-91 and ALL BFM-90m treatment first at one clinic and later at several centers. Out of 852 children with primary diagnosis of ALL admitted to Russian hematological hospitals (March 2, 1991-November 3, 2000), 687 were included into the study; 329 received the MB-91 protocol. Nine-year recurrence-free survival was 73% while overall survival--80%. Toxic side-effects after L-asparaginase were reported in 27 (7.9%). It is concluded that good results in childhood ALL treatment can be achieved without resorting to high-dosage chemotherapy and radiation in most cases.

[Treatment of acute lymphoblastic leukemia in children according to the ALL-BFM-90m protocol in the Russian Federation and the Republic of Belarus]. / Lechenie ostrogo limfoblastnogo leikoza u detei po protokolu OLL-BFM-90m v Rossiiskoi Federatsii i Respublike Belarus'.

Prognosis for children treated according to the BFM-90m protocol (Berlin-Frankfurt-Munster Group) for acute lymphoblastic leukemia (ALL) improved significantly as compared with previous modalities. Methotrexate was used in the dose of 1,000 mg/m2, 36 h. The paper presents the 10-year results for this modification. Patients aged 0-15 years were treated at hematological hospitals of Moscow, other Russian towns and in Minsk, Belarus, (July 5, 1990-November 11, 2000). BFM-90m treatment was given to 682 children out of 1,326 with primary diagnosis of ALL; a comparative trial of the MB-91 protocol hed been carried out at the same clinics since 1991. During 10 years, recurrence-free survival was 72% while overall survival--77%. Toxicity of side-effects was tolerable. The BFM-90m treatment showed significantly better results in both countries.

[Age-dependent status of the antioxidant system of rat tissues under the effect of short-term vibration]. / Vozrastnye osobennosti sostoianiia antioksidantnoi sistemy tkanei krys pri deistvii na nikh kratkovremennoi vibratsii.

Oxidation of low molecular thiols and ascorbic acid, alterations in superoxide dismutase, catalase, glutathione reductase and glucose-6-phosphate dehydrogenase activities were observed in erythrocytes and tissues of rats after short-term total vertical vibration. The rate of alterations found depended on the initial state of the antioxidative system components as well as on the vibration duration. The most pronounced impairments of the antioxidative system were detected in blood and nervous system of old animals in which the initial level of the antioxidative system functional activity was minimal.

[New data on characteristics of the chemism of erythrocytes in patients with metabolic-alimentary obesity]. / Novye dannye ob osobennostiakh khimizma éritrotsitov u bol'nykh obmenno-alimentarnym ozhireniem.

A study was made of the erythrocytic membranes in patients with stage II-III metabolic and alimentary obesity. The red blood cells may serve as model of the membranes of other cells of the internal organs, that is why their changes are likely to mirror the total impairment of the function of the cell membranes in the illness under consideration. The patients' red blood cells were characterized by high permeability, increased ATPase activity, catalase activation, reduction of the content of the thiol groups, and by the displacement of the thiol-disulfide balance towards oxidized forms. A correlation was discovered between the elevation of red blood cell permeability and red blood cell K+, Na+-ATPase activation. The changes in the thiol-disulfide balance brought about inconclusive shifts in the magnitude of permeability, in the activity of ATPase isoenzymes, and in the content of cholesterol fractions in red blood cells of patients with metabolic and alimentary obesity. The changes thus discovered are of paramount importance for understanding the pathogenesis of metabolic abnormalities associated with obesity and for rational treatment of this patients' group.

[Age-related and organ-tissue characteristics of the function of the antioxidant system in white rats]. / Vozrastnye i organotkanevye osobennosti sostoianiia antioksidantnoi sistemy belykh krys.

Various components of antioxidant system (concentration of the reduced and oxidated forms of non-protein thiol compounds and ascorbic acid, the activity of glucose-6-phosphate dehydrogenase, glutathione reductase, catalase, superoxide dismutase) have been investigated in the blood, brain and liver of growing albino rats. It was found that the specific condition of this system depends on the age of animals and on the source of the system. Disorganization of the antioxidant system in senile animals was noted which results from intensification of free radical oxidation.

[Hydrolases of the digestive organs during ontogenesis]. / Gidrolazy pishchevaritel'nykh organov v ontogeneze.

A wide variety of enzymes actualizing membrane hydrolysis of nutrients and their distribution in the gastro-intestinal tract were characterized in one-day old and adult rats and rabbits. The comparison of enzymatic activities of various animal species suggests that some enzymes are responsible for the adaptation to milk diet (lactase), others--to definitive nutrition (invertase, maltase). A number of enzymes (peptidase, alkaline phosphatase) do not depend on the type of nutrition. High activity of some hydrolases in the colon has been demonstrated confirming the A. M. Ugolev hypothesis of its digestive functions in the early ontogenesis.