Freezing and freeze-drying of strawberries with an additional effect of micro-vibrations.

Our research focuses on the formation of ice crystals and evaluating the structure of preserved frozen and freeze-dried strawberries. Strawberries were frozen in two ways. One-half of strawberries were frozen at - 30 °C under conditions of convective heat exchange. The other half of strawberries were frozen under the same conditions with an additional effect on the strawberries of micro-vibrations created in the air of the freezer according to a specific program. A digital frequency synthesizer that generates 250 W/m3 electromagnetic field rectangular pulse packets in the frequency bands of 2500-5000 kHz creates micro-vibrations. The microstructure of strawberries, the number of cells that have retained their structure and firmness were determined in frozen strawberries. The strawberries retained 25-30% of the cell structure of their total number during traditional freezing, and 65-70% of the cell structure when frozen under micro-vibration. The data of the penetration and shear stress showed that the strawberries frozen under micro-vibration conditions were 10-15% stronger. Then researched strawberries were vacuum freeze-dried. The primary drying temperature was 30 + 1 °C below zero and at the secondary drying the temperature was 38-40 °C. The microstructure and firmness of strawberries were researched in dried samples also. Freeze-dried strawberries frozen under micro-vibration had small and evenly distributed capillaries and their firmness was 8-10% higher than freeze-dried strawberries frozen by the traditional method. Thus, freezing strawberries with the additional effect of micro-vibration have a positive effect on the firmness of both frozen strawberries and freeze-dried strawberries.

[Krezatsin--a stimulant of the activity of regenerating liver cells]. / Krezatsin--stimuliator aktivnosti regeneriruiushchikh kletok pecheni.

In experiments with partial hepatectomy in rats, the application of cresacin was shown to potentiate processes of hepatocyte regeneration, to increase high-energy compounds therein, and to accelerate some phases of mitotic cycle. These processes occur along with an inhibition of lipid peroxidation in hepatocytes, a decrease in the rate of transmembrane oxygen transport in mitochondria, and a reduction of cytochrome oxidase amount. It was concluded that cresacin directly stimulates diverse links of metabolic pathway.

[Effect of vitamin A deficiency on the macromolecular permeability of small intestine mucosa in the adult rat]. / Vliianie nedostatochnosti vitamina A na pronitsaemost' slizistoi obolochki tonkoi kishki vzroslykh krys dlia makromolekul.

Adult rats with experimental vitamin A deficiency and control animals were intraperitoneally injected with chicken ovalbumin (OA) solution and the entrance of native OA into the blood was assessed 3 hours later by competitive radioimmunoassay. The OA amounts circulating in the blood of control animals averaged (0.39 +/- 0.06) X 10(-4)% of the consumed dose, while in the experimental group it averaged (1.33 +/- 0.42) 10(-4)%. Electron microscopy, using colloid lanthanum hydroxide, has shown vitamin A deficiency to give rise to an abrupt reduction in glycocalix layer, as compared to the control, without increasing erythrocyte membrane permeability for tracer particles. It is concluded that vitamin A deficiency leads to a considerable damage of small intestinal permeability for protein macromolecules.

[Hepatocyte ultrastructure in mice with chronic T-2 mycotoxicosis]. / Ul'trastruktura gepatotsitov myshei pri khronicheskom mikotoksikoze T-2.

Trichothecene mycotoxin (T-2 toxin) was administered by gastric intubation to CBAXC57BL/6 mice at a dose of 0.33-0.45 mg/kg for 6 months. No symptoms of intoxication were observed, however, electron microscopic studies revealed a severe damage of hepatocyte structure, especially of smooth and rough endoplasmic reticulum. Besides the destruction of hepatocytes an increase in the number of primary and secondary lysosomes was observed. Regenerating foci were found in the majority of liver cells. In chronic T-2 mycotoxicosis there is a strong correlation between the damage of hepatocyte ultrastructure and the changes in organella-specific enzymatic activity in the liver, that was described previously.

[Use of the OTO-method in electron microscopic studies]. / Primenenie oto-metoda pri élektronno-mikroskopicheskikh issledovaniiakh.

The modification of OTO-contrasting method (O-osmium, T-thiocarbohydrazide, O-osmium) allowing one to stain the structures of biological tissue in the process of its fixation is presented. The modification consists of an intermittent treatment of tissues with osmium tetroxide and thiocarbohydrazide after the tissue prefixation. This results in the formation of osmium-thiocarbohydrazide copolymer in form of "osmium black" and high tissue contrast corresponding to the true osmiophilia. The use of this modification permits one to give up an additional slide contrasting with a lead citrate and uranyl acetate.

[Electron microscopic study of hepato-enteric recirculation of bile components]. / Elektronnomikroskopicheskoe issledovanie pechenochno-kishechnoi retsirkuliatsii komponentov zhelchi.

Osmiophilic particles (0.05-0.1 mu) detected in enterocytes, the interepithelial space and veins were shown to represent bile micelles responsible for bile transport. Enterocytes absorb bile micelles by means of endocytosis. Most particles are transferred through the enterocyte by transit and penetrate into the interepithelial space through exocytosis. Data are obtained on bile micelles synthesis in hepatocytes and on possibility of their penetration from the blood into hepatocytes through endocytosis.

[Changes in the vessels of the kidneys in rats on a choline- and protein-deficient diet]. / Izmenenie sosudov pochek krys pri kholinobelkovoi nedostatochnosti ratsiona.

Prolonged (from 4 to 10 months) keeping of rats on a cholinoprotein- and protein-deficient diets produces an associated moderate damage to the wall on renal blood vessels and glomerulopathy. There take place dystrophic alterations in the elastic skeleton of the interlobular arteries in the form of elasticity loss and impairment of the tinctorial properties on the internal elastic membrane combined with vacuolization of the smooth muscle cells of the media.

[Vesicular transport of nutrients in the small intestine during natural feeding]. / Vezikuliarnyi transport nutrientov v tonkoi kishke pri estestvennom pitanii.

Ultrastructural aspects of the absorption of nutrients by the rat small bowel under natural feeding and administration of a food mixture homogenate to a small bowel strip were studied. It is shown that as early as 25 min after the onset of feeding, nutrients get into the proximal part of the small bowel, run across the epithelial barrier and enter the stroma of the intestinal villi and the vascular bed. Active absorption of nutrients is also observed in situ under limited intracavitary hydrolysis. The identified nutrients penetrate the apical membrane of enterocytes by pinocytosis, are detectable but inside vesicular structures of the cell, and get into the intercellular space by exocytosis. The concept of the existence of the control systems preventing foreign substances from penetration in the body and eliminating the sequels of such a penetration has been worded.

[Electron microscopic research on the mechanism of intestinal secretion]. / Elektronno-mikroskopicheskoe issledovanie mekhanizma kishechnoi sekretsii.

Electron microscopic investigation of the rat small intestine revealed a great number of vesicles 50-75 nm in diameter with enterocyte microvilli. The number of vesicles increased with the increase of digestive activity in the small intestine. Vesicles were formed by gemmation of enterocyte microvilli from the lateral membrane in contraction of microvillous actin skeleton. Simultaneously with the production of exocytotic vesicles, the formation of pinocytotic vesicles in the base of microvilli was observed. There is a supposition that the vesicle gemmation is a natural process of the intestinal secretion to fulfil numerous important function: it promotes the penetration of enterocyte hydrolases into the parietal layer; equilibrates an increase in the enterocyte volume during absorption. This is a possible way of translocation of synthesized enzymes into the cytoplasm and of transport proteins on the apical surface of epithelial cells.

[Ultrastructurometric study of the reaction of the enterocyte microvilli in the rat small intestine in natural feeding]. / Ul'trastrukturometricheskoe issledovanie reaktsii mikrovorsinok énterotsitov tonkoi kishki krys pri estestvennom kormlenii.

A study was made of the time-course of changes in the length of the microvilli at three main sites of the rat small intestine after natural feeding with a mixture of milk, bread and sunflower seeds. The length of the microvilli during fasting was shown to be maximal in the upper third of the villi and minimal in the apical pole of the villi. After feeding the microvilli experienced shortening which was least marked in the ileum. The morphometric parameters of the microvilli response in enterocytes of the intestinal parts under test are provided depending on their location on the villi. Actomyosin complex of the microvilli was found to take an active part in absorption. The findings confirm the hypothesis of the pinocytic mechanism by which the nutrients are absorbed.

[Effect of T-2 toxin on organ ultrastructure and organelle-specific enzyme activity in rats]. / Vliianie T-2 toksina na ul'trastrukturu i aktivnost' organello-spetsificheskikh fermentov nekotorykh organov krys.

The time-course of the ultrastructural changes and activities of 6 marker enzymes of subcellular particles (succinate dehydrogenase, beta-glucosidase, beta-N-acetylglucosaminidase, acid RNAse, glucose-6-phosphatase and 5'-nucleotidase) has been studied in the liver, spleen and thymus in rats administered T-2 toxin (mycotoxin produced by some Fusarium species). A pronounced difference in the effect of T-2 toxin on the organs has been found. In the liver, the toxin induced a destruction of rough endoplasmic reticulum membranes, reduced ribosome number and progressively decreased activities of most enzymes. In the spleen, early and significant ultrastructural disturbances of all the cell membrane components and simultaneous lysosomal activation were observed. The changes in the thymus were characterized by a fast development of cell hydratation, organelle swelling and necrosis of some thymocytes with parallel increase in repair processes, infiltration by phagocytes and a selective activation of lysosomal hydrolases in the end of experimental time (72 h.). The results obtained emphasize an importance of cellular and subcellular membrane alterations in the mechanism of T-2 toxin action.