Assessing osseointegration of metallic implants with boronized surface treatment.

BACKGROUND: Modification of endosteal implants through surface treatments have been investigated to improve osseointegration. Boronization has demonstrated favorable mechanical properties, but limited studies have assessed translational, in vivo outcomes. This study investigated the effect of implant surface boronization on bone healing. MATERIAL AND METHODS: Two implant surface roughness profiles (acid etched, machined) in CP titanium (type II) alloy implants were boronized by solid-state diffusion until 10-15µm boron coating was achieved. The surface-treated implants were placed bilaterally into 5 adult sheep ilia for three and six weeks. Four implant groups were tested: boronized machined (BM), boronized acid-etched (BAA), control machined (CM), and control acid-etched (CAA). Osseointegration was quantified by calculating bone to implant contact (BIC) and bone area fraction occupancy (BAFO). RESULTS: Both implant types treated with boronization had BIC values not statistically different from machined control implants at t=3 weeks, and significantly less than acid-etched control (p<0.02). BAFO values were not statistically different for all 3-week groups except machined control (significantly less at p <0.02). BAFO had a significant downward trend from 3 to 6 weeks in both boronized implant types (p<0.03) while both control implant types had significant increases in BIC and BAFO from 3 to 6 weeks. CONCLUSIONS: Non-decalcified histology depicted intramembranous-like healing/remodeling in bone for controls, but an absence of this dynamic process in bone for boronized implants. These findings are inconsistent with in vitro work describing bone regenerative properties of elemental Boron and suggests that effects of boron on in vivo bone healing warrant further investigation.

[Effect of LIF factor on lipid bilayer].

It has been found that the recombinant protein LIF induces jumps of current in bilayer lipid membranes, which indicates the formation of ionic channels. Some properties of these channels (dependence on voltage, sing of potential, ionic strength of solution, and lipid composition) were studied. A difference between the effects of protein LIF of eukaryotic and prokaryotic origin was shown.

[The influence of LIF (leukemia inhibitory factor) on the functional status of mouse line R1 embryonic stem cells].

The influence of cytokine LIF (Leukemia Inhibitory Factor) on the viability, and proliferation of mouse R1 line embryonic stem cells (ESC) and their distribution by cell cycle stages has been investigated. LIF (5-20 ng/ml) increased growth of colonies and maintained high proliferative and pluripotent properties of R1. LIF was also involved into the inhibition of spontaneous cell differentiation and apoptotic cell death; it also decreased the rations of S/G2+M cell cycle and doubling-time of cell population.

[Differentiation of embryonic stem cells into cardiomyocytes with the help of cytokine LIF (leukemia inhibitory factor)].

An experimental model of differentiated mouse embryonic stem cells with retractive activity similar to that of cardiomyocytes without preliminary formation of embryoid bodies was obtained. The basic factor that induced in vitro embryonic cell differentiation into cardial type is the recombinant cytokine LIF under prolonged cultivation. The positive reaction of the cells with retractive activity to isoproterenol indicates the presence of the beta-adrenergic receptor activity characteristic only for terminal differentiated mammalian cardiomyocytes.

[Evaluation of pollution of an urban area by level of heavy metals in snow cover]. / Otsenka zagriazneniia gorodskoi territorii po soderzhaniiu tiazhelykh metallov v snezhnom pokrove.

The goal of this study was to systematize various methodological approaches to evaluating the contamination of the snow cover with heavy metals (HM) by using Kazan, an industrial city with diversified industry, as an example. The findings suggest that it is necessary to characterize the contamination of the snow cover by the actual entrance of an element per area unit of the snow cover for a definite period of time rather than by the concentration of TM in the volume unit of snow water (mg/l), which minimizes the uncertainties with spatial and temporary snow cover variations. The index of the maximum allowable entrance, which is of practical value, may be used to objectively calibrate the pollution of the snow cover, by estimating the amount of a coming element and its toxicity.

Study of fossil tracks due to 50 < or = Z < or = 92 galactic cosmic ray nuclei in meteoritic crystals: results and perspectives.

A new approach to the problem of investigation of charge and energy spectra of ultra heavy Galactic cosmic ray nuclei, based on fossil track study of extraterrestrial olivine crystals has been developed. The results of an investigation of ultra heavy Galactic cosmic ray nuclei (Z=50-92) in meteoritic olivine crystals are presented. The technique was based on calibration of olivine crystals with accelerated Xe, Au, Pb and U ions and well-controlled partial annealing of "fresh" and "fossil" tracks. It allows us to determine the charge spectra and abundances of cosmic ray nuclei based on fossil track length study in meteoritic and Moon crystals. The comparative studies of the spectra of "fossil' tracks and tracks due to 208Pb and 238U nuclei have shown that the group of 210 micrometers "fossil" tracks, first observed in 1980 at JINR is due to Th-U nuclei-products of recent r-process nucleosynthesis in our Galaxy. The method in principle allows one to resolve Pt-Pb peaks in fossil tracks, to establish the upper limit of the abundance of Z>110 nuclei in the Galactic cosmic rays at the level < or = 10(-3) to the abundance of actinide nuclei and to get information on the history of Z>50 cosmic ray nuclei in time interval up to 220 M.Y.

[Toxicologic evaluation of propyneb on the Wistar rat]. / Evaluation toxicologique du propyneb chez le rat Wistar.

This experiment was performed in Wistar rats of both sexes exposed subchronically to 1:100, 1:500, 1:1000 and 1:1500 LD50. The evaluation was based on endpoints measured on the 30th and 90th after starting exposure and after a recovery period of 30 days: these included clinical signs, functional changes, hematological parameters, urine analysis, biochemical, histochemical, immunomorphological endpoints, electron microscopy of internal organs, chromosome examination of bone marrow. A high lethality was shown to occur with a characteristic clinical picture: interruption of weight gain, behavioural changes, leucopenia mainly involving neutrophil leucocytes, biochemical changes characteristic of liver, cardio-vascular system (myocardium and aorta) together with pathologic, biochemical, histochemical and ultrastructural changes in liver, brain, thyroid gland, myocardium, spleen and bone marrow. Endpoints were shown to be clearly dose-dependently related with small variations with the low dose, i.e. 1:1500 LD50 (5 mg/kg-1 bw).

[The effect of the motor regimen on the state of the blood circulation in 6-year-old children in kindergarten]. / Vliianie dvigatel'nogo rezhima na sostoianie krovoobrashcheniia u 6-letnykh detei v usloviiakh detskogo sada.

Six-year old children attending day-care centers' groups with different motor regimens (a regular group and experimental classes where children spend 2.5-3.5 hours a day at the desk) were examined at the beginning (September) and at the end (May) of a school year for the following parameters: arterial blood pressure, pulse and breathing rate, as well as a step of regulation of the cardiac rhythm and spontaneous motor activity (determined with the help of coherent optics equipment according to ECG and actogram recordings). It has been found out that children from the experimental class have the bloodcirculation regulation status which is worse than that in children following a regular regimen. The authors suppose that it might be due to the reduction of physical activity.

A possible correlation of electro-optic changes with the deformability of erythrocytes.

A novel electro-optical technique for deformability measurement is described. This method is faster and more convenient than "standard" procedures. Erythrocytes (RBC, 10(6) cells/mL suspended in isotonic sucrose 10%, ionic strength 10(-4) M/L, pH 6.5) are ordered in an electric field (E = 10(4) Vp-p/m, v = 10(3) Hz) following the field direction, as a result of an induced electric dipole moment. After the switching off of the electric field, a certain time is required for the electro-optic effect to subside. Under the action of thermal motion, the suspended erythrocytes virtually return to their initial unordered state. The decay time (return time) is the investigated parameter. Results show that if erythrocyte deformability is reduced, the return time is longer than in control RBC. Suspensions of erythrocytes with reduced deformability, achieved by treatment with glutaraldehyde at concentrations ranging from 10(-8) to 10(-1) M/L, are measured. The suggested electro-optic method has good precision and requires a very small quantity of blood (about 0.1 mL), which makes it potentially useful in clinical practice.

[The effect of diet therapy on the hormonal spectrum of patients with bronchial asthma]. / Vliianie dieticheskoi terapii na gormonal'nyi spektr u bol'nykh bronkhial'noi astmoi.

Results are reported of an investigation of the levels of cortisol, pancreatic and thyroid hormones in 38 patients with the infectious-allergic form of bronchial asthma. Unloading dietotherapy was accompanied by an improvement of the clinical course of the disease, reduction of necessity in broncholytic and hormonal agents. During the unloading dietotherapy period some variants of hormonal response to hunger were revealed. Patients with a severe course of the acidotic crisis revealed a reduction of the insulin level, changes in the cortisol dynamics, T4, a tendency to an increase of T3 in the blood.

Neurotropin effect on the deformability and electrophoretic mobility of rabbit erythrocytes.

The effect of neurotropin (a drug with antioxidant action) on the deformability and electrophoretic mobility (EM) of rabbit erythrocytes was investigated and compared to that of endotoxin from E. Coli (0111:B4) using an electrooptical technique. Endotoxin decreased the erythrocyte deformability in vitro. Upon incubation with neurotropin the endotoxin effect was reversed, i.e. the deformability of the erythrocytes increased. The electrophoretic mobility of red blood cells exposed to the simultaneous action of endotoxin and neurotropin was substantially closer to that of the control cells, as compared to the one of erythrocytes incubated with endotoxin alone. Neurotropin (1 mg.kg-1 given 1 hour after endotoxin administration) decreased the mortality of the animals, injected with endotoxin (2 mg.kg-1) namely by in the first day 63.6% versus 9.1%.