Cytochrome c-poly(acrylic acid) conjugates with improved peroxidase turnover number.

Cytochrome c-poly(acrylic acid) (cyt c-PAA) conjugates with 34-fold enchancement in peroxidase turnover number (kcat) are reported. Cyt c-PAA conjugates were prepared by carbodiimide coupling. PAA with molecular weight (Mw) ranging from 1.8k to 250k g mol-1 were employed, and the effect of PAA Mw on peroxiodase kinetics was assessed. The kcat value increased with increased Mw of PAA, ranging from 0.077(±0.002) s-1 in the absence of PAA to 2.66(±0.08) s-1 for the conjugate of cyt c with 250k PAA. Enzymatic activity studies over pH 6-8 indicated improved activity for cyt c-PAA conjugates at neutral or slightly alkaline pH. Examination of the cyt c heme spectroscopy in the presence of H2O2 revealed that formation of compound III, a reactive intermediate that leads to enzyme inactivation, was supressed in cyt c-PAA conjugates. Thus, we suggest the kcat enhancement can be attributed to acidification of the pH microenvironment and inhibition of the formation of a reactive intermediate that deactivates cyt c during the catalytic cycle.

Analysis of the Efficiency of Microencapsulated Sustained-Release Form of Naloxone on the Experimental Model of Fentanyl Poisoning.

We compared samples of microencapsulated naloxone prepared by using spray drying technique. 2-Hydroxypropyl-ß-cyclodextrin, sodium alginate, polycaprolactone, and carboxymethyl cellulose were used as the carriers. It was found that the combination of naloxone with sodium alginate was characterized by the highest naloxone content in the matrix and the lowest release rate (100% release time was 60 min). Using the model of respiratory disturbances caused by 10 ED50 fentanyl (anesthetic effect), we studied the effects of naloxone-sodium alginate complex on the dynamics of CO2 concentration in the expired air. It was shown that treatment with the developed microencapsulated naloxone after fentanyl injection allowed reducing the therapeutic dose of the antagonist by more than 2 times and eliminated the necessity of repeated injections.

[Pharmacological activity of n-(1-phenethyl-4-piperidyl) propionanilide modified by encapsulation in PLGA nanoparticles].

Technological parameters for the effective encapsulation of n-(1-phenethyl-4-piperidyl)propionanilide in poly(lactid-co-glycolide) (PLG) nanoparticles have been determined. Depending on the ratio of drug fractions adsorbed on the particle surface and associated with the polymer matrix, n-(1-phenethyl-4-piperidyl)propionanilide (200 microg/kg, i/m) loaded PLG nanospheres accelerated time onset and increased duration of sleep in rats: by a factor of 1.6 - 2.0 for polymer associated drug fraction within 40 - 60% and by a factor of 2.2 - 2.6 for polymer associated drug fraction within 60 - 80%. A similar increase of sleep duration was observed when free n-(1-phenethyl-4-piperidyl)-propionanilide was administered at doses within 400 - 500 microg/kg.

[Combined use of local anesthetic with clonidine in cases of tooth extraction].

The technique of local anesthesia by lidocain in combination with clonidine (clofelinum) as vasoconstrictor in the dose of 1 microg/kg was compared with local anesthesia by novocain in combination with adrenaline (1:200 000) or by lidocain without vasoconstrictor or by articain in combination with adrenaline (0.012 mg/ml). Lidocain use led to expressed tachycardia and considerable increase of cardiac oufput in moderate hypertension reactions. Adrenaline addition in anesthetic solution increases general peripheral resistance and all parameters of arterial pressure with simultaneous rise of heart contractions. Adrenaline substitution as local vasoconstrictor for clofelinum decreases sympathetic tension during operation, prevents hypertensive reactions as the result of general peripheral resistance decrease, stabilizes heart rhythm and basic indices of central hemodynamics, that testifies to its (technique) adequacy.

Reduced extractability of the XPA DNA repair protein in ultraviolet light-irradiated mammalian cells.

The XPA protein is essential for both of the known modes of nucleotide excision repair (NER) in human cells: transcription-coupled repair (TCR) and global genome repair (GGR). In TCR, this protein is thought to be recruited to lesion sites in DNA at which RNA polymerase II is blocked and in GGR, by direct recognition of damages by repair protein complex containing XPC/HR23B or DNA damage-binding protein. However, details of the recruitment of the XPA protein in vivo are unknown. It was shown earlier that a portion of another NER protein, PCNA, which is completely extractable from non-S-phase mammalian nuclei, becomes insoluble after ultraviolet (UV) light irradiation and cannot be extracted by methanol or buffer containing Triton X-100. In the present study, we have found that UV light irradiation of human or Chinese hamster cells leads to decrease of extractability of the XPA protein by Triton X-100. Maximal insolubilization of the XPA protein is observed 1-4 h after irradiation but it is not detectable by 22 h. This effect is dose-dependent for UV light from 2.5 to 15 J/m(2) and is unaffected by the pre-treatment of cells with sodium butyrate, an inhibitor of histone deacetylation. The UV light-induced insolubilization of the XPA protein was also observed in two lines of Cockayne syndrome complementation group A cells, indicating that the effect is not dependent upon TCR. The results are discussed in relation to possible mechanisms of NER.

[General status of patients before dental treatment]. / Obshchee sostoianie bol'nykh pered lecheniem u stomatologa.

Arterial pressure (AP), heart rate, and stress index (estimated by ECG) were measured in 20 patients several minutes before dental treatment. Systolic AP was normal in 56% patients (mainly elderly), diastolic was normal in 50.5% and increased in 36% (particularly so in elderly patients). Heart rats was normal in 33% patients, the rest had bradycardia (6%) or tachycardia (61%); the latter condition was more typical of young patients and was paralleled by high systolic AP. 10.5% patients had normal stress index and in 87.5% it was increased, indicating extreme stress of the sympathoadrenal system. All 4 parameters were normal in 3.5% patients, half of whom were youths aged under 20 years. 10.5% examinees had three normal parameters, 32.5% had two normal parameters, and 37.5% had one normal parameters; 16% examinees had all parameters beyond the threshold values. The authors point to the double hazard of such a state (possible complications and decreased pain sensitivity) and emphasize the need in preventive measures to correct the general status of patients.