Solid-state dynamics and single-crystal to single-crystal structural transformations in octakis(3-chloropropyl)octasilsesquioxane and octavinyloctasilsesquioxane.

Reactive octahedral silsesquioxanes of rod-like [octakis(3-chloropropyl)octasilsesquioxane - T8(CH2CH2CH2Cl)8] and spherical [octavinyloctasilsesquioxane - T8(CH[double bond, length as m-dash]CH2)8] structure can undergo reversible thermally induced phase transitions in the solid state. The phase behaviour has been studied with differential scanning calorimetry (DSC, including temperature modulated DSC), X-ray diffraction, dielectric relaxation spectroscopy (DRS), and nuclear magnetic resonance spectroscopy in the solid state (SS NMR), as well as positron annihilation lifetime spectroscopy (PALS) and polarized optical microscopy (POM). The mechanisms involving fitting the molecules into most symmetrical crystal lattices vary for species of different structure. Thermal energy can be used to expand the crystal lattice leading to thermochromism in the case of T8(CH[double bond, length as m-dash]CH2)8 or conversely to an unusual negative thermal expansion of crystals of T8(CH2CH2CH2Cl)8 that results in their self-actuation. The complex behaviour is reflected in unusual changes in the capacitance and fractional free volume of the material. These phenomena can be used for molecular design of advanced well-defined hybrid materials capable of reversible thermally induced structural transformations. The findings present a new perspective for POSS-based flexible metal-organic frameworks (MOF) of cooperative structural transformability via entropy-based translational sub-net sliding.

[Influence of patient age and year of developing the disease on immunologic response to measles virus in subacute sclerosing panencephalitis (SSPE)]. / Wplyw wieku chorych i roku zachorowania na odpowiedz immunologiczna dla wirusa odry u osób z podostrym stwardniejacym zapaleniem mózgu (SSPE).

Analyses were concerning 338 SSPE patients investigated in the years 1984-1989 from a group in which 305 persons were known regarding year of illness development and their age at the time of sample taking. The analysis has shown statistically significant decrease of antibodies against measles virus with increase of age of tested patients. At the same time, it was found that in persons who developed disease in 1983-1985 and in 1988, increase of mean value of antibodies against measles virus was evident during first 2-3 years from beginning of the SSPE. Comparison of mean values of antibodies against measles virus in age groups of SSPE patients and normal population, revealed existence of relation between these groups where source of antibodies constituted of a wild measles virus. Our analyses indicate influence of measles wild virus circulating in the population on immunological response to this virus in sera of patients with SSPE.

[Use of western blotting methods in diagnosis of viral infection causing tick-borne encephalitis]. / Zastosowanie metody western blott w diagnostyce zakazen wirusem kleszczowego zapalenia mózgu.

A Western blot method for investigation of antigens and of immunological response to tick-borne encephalitis was prepared. An analysis was performed testing cross reactions of proteins of prepared antigen with sera for four Polish strains of tick-borne encephalitis and four other flaviviruses. Usefulness for diagnosis of infections in humans was determined by comparison of Western blot method with ELISA immunoenzymatic test. It was found that elaborated method permits equally as ELISA for evaluation of immune response in immunoglobulin classes. By evaluation of response for individual virus components, Western blot method enables at the same time verifications of nonspecific determinations which result from reaction of antibodies present in tested diagnostic materials with nonviral antigens.

Siloxane and silsesquioxane molecules--precursors for silicate materials.

Preparation of ceramics by sol-gel method has been known for many years, but recently it has been developed as a method for the synthesis of nanostructural ceramic materials. Hydrolytic polycondensation of simple molecules [e.g. most widely used tetraethoxysilane (TEOS)] leads to xerogel materials that can contain macromolecules of distinct random, ladder and cage or partial cage structure. In order to obtain well-defined silsesquioxanes it is preferred to start the process with more complex molecules, bringing in a specific framework that can govern the structure of the product. In the presented work alkoxy derivatives of cyclosiloxanes and polysiloxanes as well as a hydride derivative of octahedral silsequioxane (T(8)(H)) were applied as precursors in the process of hydrolytic polycondensation. Depending on the reaction conditions, silsesquioxane macromolecules or silica material of ordered structure were obtained. We have prepared mesoporous organiosilica materials without using any template or surfactant whatsoever. The meso-pores are created due to the unique structure of initial oligosiloxane or silsequioxane molecules and the specific interactions in the used catalyst/solvent system. In the case of octasilsesquioxane precursor, the condensation process gives directly mesoporous silica material. Dried polysilsesquioxanes were heated at the temperature of 600°C in argon or air atmosphere (pyrolysis or ceramization). In the atmosphere of argon SiC(x)O(y) glass materials were obtained.

Short-term fasting and lipolytic activity in rat adipocytes.

The aim of this experiment was to study the influence of 18-hour food deprivation on basal and stimulated lipolysis in adipocytes obtained from young male Wistar rats. Fat cells from fed and fasted rats were isolated from the epididymal adipose tissue by collagenase digestion. Adipocytes were incubated in Krebs-Ringer buffer (pH 7.4, 37 degrees C) without agents affecting lipolysis and with different lipolytic stimulators (epinephrine, forskolin, dibutyryl-cAMP, theophylline, DPCPX, amrinone) or inhibitors (PIA, H-89, insulin). After 60 min of incubation, glycerol and, in some cases, also fatty acids released from adipocytes to the incubation medium were determined. Basal lipolysis was substantially potentiated in cells of fasted rats in comparison to adipocytes isolated from fed animals. The inhibition of protein kinase A activity by H-89 partially suppressed lipolysis in both groups of adipocytes, but did not eliminate this difference. The agonist of adenosine A (1) receptor also did not suppress fasting-enhanced basal lipolysis. The epinephrine-induced triglyceride breakdown was also enhanced by fasting. Similarly, the direct activation of adenylyl cyclase by forskolin or protein kinase A by dibutyryl-cAMP resulted in a higher lipolytic response in cells derived from fasted animals. These results indicate that the fasting-induced rise in lipolysis results predominantly from changes in the lipolytic cascade downstream from protein kinase A. The antagonism of the adenosine A (1) receptor and the inhibition of cAMP phosphodiesterase also induced lipolysis, which was potentiated by food deprivation. Moreover, the rise in basal and epinephrine-stimulated lipolysis in adipocytes of fasted rats was shown to be associated with a diminished non-esterified fatty acids/glycerol molar ratio. This effect was presumably due to increased re-esterification of triglyceride-derived fatty acids in cells of fasted rats. Comparing fed and fasted rats for the antilipolytic effect of insulin in adipocytes revealed that short-term food deprivation resulted in a substantial deterioration of the ability of insulin to suppress epinephrine-induced lipolysis.