The sensitivity mechanisms of a bipolar magnetotransistor. Part 1

Investigations of a bipolar magnetotransistor have shown that its sensitivity is determined by a concentration-recombination mechanism, which depends on the magnetic induction, and it increases in weak magnetic fields. When the base-emitter bias voltage changes, the sign of the relative current sensitivity changes, and its maximum value when measuring a magnetic field of induction 0.3 mT amounts to 3300 T⁻¹. __________ Translated from Izmeritel’naya Tekhnika, No. 11, pp. 39–44, November, 2006.     

Biologically active amphiphilic derivatives of chitosan

Amphiphilic N-derivatives of chitosan containing C₁₂ alkyl and carboxyl groups were obtained. It was shown that the compounds obtained have fungicidal activity and form intermolecular associates in solutions. __________ Translated from Khimicheskie Volokna, No. 6, pp. 57–58, November–December, 2005.     

N-Heterocyclic Carbenes and Their Metal Complexes Based on Histidine and Histamine Derivatives of Bacteriopurpurinimide for the Combined Chemo- and Photodynamic Therapy of Cancer

Photodynamic therapy (PDT) is currently regarded as a promising method for the treatment of oncological diseases. However, it involves a number of limitations related to the specific features of the method and the specific characteristics of photosensitizer molecules, including tumor hypoxia, small depth of light penetration into the tumor tissue, and low accumulation sensitivity. These drawbacks can be overcome by combining PDT with other treatment methods, for example, chemotherapy. In this work, we were the first to obtain agents that contain bacteriopurpurinimide as a photodynamic subunit and complexes of gold(I) that implement the chemotherapy effect. To bind the latter agents, N-heterocyclic carbenes (NHC) based on histidine and histamine were obtained. We considered alternative techniques for synthesizing the target conjugates and selected an optimal one that enabled the production of preparative amounts for biological assays. In vitro studies showed that all the compounds obtained exhibited high photoinduced activity. The C-donor Au(I) complexes exhibited the maximum specific activity at longer incubation times compared to the other derivatives, both under exposure to light and without irradiation. In in vivo studies, the presence of histamine in the NHC-derivative of dipropoxy-BPI (7b) had no significant effect on its antitumor action, whereas the Au(I) metal complex of histamine NHC-derivative with BPI (8b) resulted in enhanced antitumor activity and in an increased number of remissions after photodynamic treatment.     

Changes in the impulse activity of neurons of the human thalamic ventrolateral nucleus during voluntary movement

Functional differences were revealed in evoked activity of two types (A and B) of units of the human thalamic ventro-lateral nucleus (VL). Collective activities of these polyfunctional neurons were selectively related to triggering and execution phases of movement. Common character of dynamics of the responses seems to be due to similar polyfunctional nature as well as to the functional role of these two complementary elements in the motor signal transmission. The collective activities reflect in the VL the integrative processes related to processing and programming of generalised parameters of motor signals, but unrelated to performance of a concrete motor act.     

New methods of rectum and colon x-ray study in patients with constipation

In the 14, 3 and 90 day-experiments with tail-suspended rats, histochemical determination of myosin ATP-ase activity in m. soleus and m. gastrocnemius preincubated in acid and neutral media was followed by measurement of the cross-sectional areas (CSAs) of muscular fibers (MF) and calculation of the percentage of various types of MF. By day 30 of testing atrophy in m. soleus reached maximum and stabilized. By that time, MF CSAs were less than in the control by 69, 62, and 68% in MF-I, -IIA and -IIC, respectively. Slow MF underwent the transformation into fast and intermediate. In slow MF this process peaked by day 3 when the number of these fibers decreased by 28% as compared to the control, and stabilized. The transformation of intermediate fibers into the fast ones was progressing simultaneously. This process was not finished by day 90. Atrophy of m. gastrocnemius was less pronounced than in m. soleus. On day 14 of experiment, MF CSAs, except for IIB, were by 30% smaller than in the control. Type IIB MF were less affected as their CSAs decreased by only 17% as compared with the control. On day 90, CSAs in both slow and IIC-type fast MFs remained approximately same as in the rats investigated on day 14. Fast MF CSAs either tended to (IIA) or regained (IIB) the norm. Hence, atrophy in m. gastrocnemius stabilized earlier than in m. soleus. Besides, longer suspension led to a partial or complete reconstruction of two out of three types of fast fibers. The percent ratio of MFs was unchanged; however, during the ATP-ase determination slow IB-type MFs assumed th color typical of fast MFs.     

Thin Films of Cadmium and Dysprosium Oxides as Gas-Sensitive Elements of Sensors

Polycrystalline nanofilms of Dy₂O₃ and CdO are prepared by hydropyrolysis from aqueous solutions of dysprosium and cadmium nitrate salts. The surface morphology of the films and their polycrystalline structure are investigated by X-ray diffraction and electron microscopy. The synthesis of powders is performed by thermolysis of aqueous solutions of cadmium and dysprosium nitrates. The sequence of formation and crystallization of oxide phases of CdO and Dy₂O₃ is ascertained from the X-ray powder diffraction data. The temperature dependence of the electrical resistance of the films obtained is studied in air and argon atmosphere.     

The current course and treatment of infectious endocarditis

Clinical study of 172 patients treated in the Burdenko Military Hospital for subacute infectious endocarditis in 1980-1996 compared with 192 cases in 1950-1979. Contemporary course of the disease is attended by a few symptoms, primordiality and single-valve affection. On the grounds of antibiotics sensitivity of the most prevalent infection agents discovered in 1996, the article develops some schemes of antibacterial therapy for Streptococcus, Enterococcus and staphylococcal etiology of disease. Rational antibiotic therapy together with surgery measures reduced lethality to 14.3% for Streptococcus endocarditis, to 16.7%--for Enterococcus and to 34.4%--for Staphylococcus.