Serial measurements of body composition in obese subjects during a very-low-energy diet (VLED) comparing bioelectrical impedance with hydrodensitometry

Bioelectrical impedance analysis (BIA) is a convenient, inexpensive, and noninvasive technique for measuring body composition. BIA has been strongly correlated with total body water (TBW) and also has been validated against hydrodensitometry (HD). The accuracy and clinical utility of BIA and HD during periods of substantial weight loss remain controversial. We measured body composition in moderately and severely obese patients serially using both methods during a very-low-energy diet (VLED). Mean initial weight in these patients was 116 (+/-30) kg (range, 74-196 kg). Mean weight loss was 24 (+/-13) kg with a decrease in fat mass (FM) by HD of kg (p < 0.001) and a decrease in fat-free mass (FFM) of 3.6 kg (p < 0.05). Loss of FFM is best predicted by the rate (kg/wk) of weight loss (r2 = 0.86, p < 0.0001). FFM, as predicted from BIA equations, was highly correlated with FFM as estimated by HD during all testing sessions (r = 0.92-0.98). Although highly correlated, BIA overestimated FFM relative to HD and this difference appeared to be more pronounced for taller patients with greater truncal obesity. Although the discrepancy was no greater during weight-loss treatment, the level of disagreement was considerable. Therefore, the two methods cannot be used interchangeably to monitor relative changes in body composition in patients with obesity during treatment with VLED. The discrepancy between BIA and HD may be caused by body mass distribution considerations and by perturbations in TBW which affect the hydration quotient for FFM (BIA) and/or which affect the density constants for FFM and FM (HD).     

A technique for selecting γ rays with energies above 50 GeV from the background of charged particles in the GAMMA-400 space-based γ-ray telescope

The task of selecting neutral γ rays from the background of charged particle fluxes, which arises in investigation of high-energy (>50 GeV) cosmic rays, is complicated by the presence of the backsplash effect. The backsplash is composed of a great number of low-energy (~1 MeV) particles produced in an electromagnetic shower being developed in the calorimeter of the γ-ray telescope. A technique of charged particle rejection using an anticoincidence system has been developed. A method for discriminating events of charged particle detection from γ-ray detection events accompanied by the backsplash phenomenon is proposed. This method is based on the difference of the signals in time and makes it possible to maintain a high detection efficiency even for high-energy γ rays.     

Simulation of nanochannel membrane formation

Monte Carlo simulations of atomic processes on the surface of silicon nanochannel membranes during molecular-beam epitaxy and subsequent thermal oxidation are performed. It is demonstrated that silicon deposition on Si(001) wafers with 1–100 nm cylindrical pores results in constriction of channel inlets. The rates of reduction of the nanochannel diameter are estimated as functions of the wafer temperature, silicon deposition rate, and initial nanochannel diameter. Optimal conditions of silicon deposition on nanochannel membranes are determined: the wafer temperature of 250–450°C and silicon flux intensity of 10⁻² to 10 monolayers (ML) per second. Under these conditions, the rate of reduction of the nanochannel inlet diameter is 0.13–0.15 nm/ML, which allows membrane channel modifications over a wide range down to several nanometers. Simulations of nanochannel membrane oxidation in an oxygen flux shows that precise reduction of nanochannel inlet diameters down to complete sealing of the channel due to oxide growth is only possible for small diameters of the initial pores. For channels with large lateral sizes, the effect of reduction of the channel inlet diameter due to oxidation is insignificant. Oxidation of pores enhances their stability to subsequent high-temperature treatment.     

Certain aspects of sheet glass coloring

The Saratov Institute of Glass uses local raw materials with substantial deviations from standard parameters in production of thermally polished light- and heat-absorbing glass. A block system for prediction and fine correction of the color and light characteristics of tinted glass is developed in terms of using local material resources (sand, chalk, and dolomite).     

Sotahexal pharmacodynamics in patients with ischemic heart disease

Therapeutic and prophylactic antiarrhythmic efficacy of sotalol hydrochloride (Sotahexal, "Hexal", Germany) and its effects in intracardiac hemodynamics and ECG parameters were evaluated in 95 patients with ischemic heart disease (IHD). The highest response to the drug was observed in ventricular extrasystoles, arterial flutter and fibrillation. Acute episodes of arrhythmia are managed by bolus administration of Sotahexal [correction of Hexal]. In this case greater risk of side effects exists. It is desirable to decide on the drug dose, mode of administration on the individual basis with due consideration of the risks and dangers which could be avoided in case of adequate instrumental control.     

Movement disorders in the context of P.K. Anokhin's theory of functional systems

The authors' own findings and the data available in the literature as to movement diseases (MD) in animals and man were reviewed in the context of P. K. Anokhin's theory of functional systems. The functional system of the human body's gravity center is detailed. There is evidence for that disintegration processes underlying MD first occur in the mnestic sphere since due to genetic and/or ontogenetic causes, memory has no preserved no motor programme required to achieve the end net efficiency of performance of this functional system,--to maintain the definite position of the gravity center of the body and its related vegetative status upon stress-induced vestibular exposures. Based on the above concepts of the pathogenesis of MD, its preventive measures have been proposed and tested, which include drug (nootropic agents) and non-drug (a special complex of physical exercises for children aged 2 to 7 years, which will form permanent motor programs in memory in definite periods of their ontogenesis) measures.     

Experience in the health promotion of children in opisthorchiasis foci

The analysis covers 2555 appendectomies, performed on an emergency and scheduled surgery basis in the clinic of emergency surgery.--State University Hospital "Queen Giovanna", Sofia, over the period 1985-1997. Relaparotomy is necessitated in 28 cases (1.09 per cent) because of various postoperative complications. Data are presented on the number of relaparotomies, done under conditions of emergency and scheduled surgery, and with a special reference to the pathoanatomical character of appendicitis. The underlying causes of undertaking relaparotomy and postoperative lethality are analyzed. As shown by the obtained results post-relaparotomy mortality rate is the highest after primary operation for destructive form of appendicitis and advanced form of peritonitis.     

Synthesis of the nitrogen-fixing enzyme system in oligonitrophilic bacteria

Oligonitrophilic bacteria were cultivated on a medium containing only 2.5--10.0 mg/litre of nitrogen compounds. They assimilated elementary nitrogen only after utilization of these nitrogen compounds during growth and formation of nitrogen-fixing enzyme system. Their cells grown on a medium containing high concentrations of bound nitrogen did not fix nitrogen during further incubation in the atmosphere of 15N; therefore, the enzymes involved in nitrogen fixation were induced. These organisms are characterized by diauxia during their growth on media containing "start" doses of nitrogen. Enzymes catalysing nitrogen fixation in azotobacter are also induced. But, contrary to oligonitrophilic bacteria, the azotobacter does not require nitrogen compounds in the medium in order to adapt to molecular nitrogen, and its growth curve is not of a biphasal character. These data and the evidence of other authors suggest that all nitrogen-fixing microorganisms are characterized by the induced, not constitutive, enzymes involved in reduction of molecular nitrogen.