Neutral alpha-mannosidase in human B- and T-lymphoid cells]

The presence of neutral alpha-mannosidase activity in normal and pathological lymphoid cells has been demonstrated. The specific activities of the enzyme in different cell types were similar with the exception of B-cells from B-CLL patients when it was a little higher. The activity of acid alpha-mannosidase was also determined in these lymphoid cells. The neutral to acid alpha-mannosidase activity ratio was different in B- and T-cells: in the former neutral alpha-mannosidase activity prevailed, whereas in the latter the predominance of acid alpha-mannosidase activity was apparent. Neutral alpha-mannosidases from pathological B- and T-cells were partially purified and their properties were investigated. In both cell types the enzyme was localized in the cytosol, was very labile and could be stabilized with Mn2+ and dithiothreitol. The enzyme was activated by Co2+ and inhibited by Zn2+ and EDTA. Swainsonine inhibited the B-cell neutral alpha-mannosidase somewhat more strongly in comparison with the T-cell enzyme.     

Acid glycosidases of normal cattle lymphocytes and in chronic lympholeukemia

The activity of five acid glycosidases was determined in lymphocytes from normal animals and animals with chronic lymphocytic leukemia. It was shown that alpha-D-mannosidase activity in leukemic lymphocytes was 5 times lower (p less than less than 0.001) and alpha-D-glucosidase activity was 2 times lower (p less than 0.01) than in normal controls. The progress of the disease and the increase in leukocyte count were accompanied by the decrease in alpha-D-mannosidase activity. No differences have been found in alpha-D-mannosidase properties (thermostability, Km values, ZnSl2 activation) in normal and leukemic lymphocytes.     

European checkerspots (Melitaeini: Lepidoptera,Nymphalidae) are not aposematic – the point of view of great tits (Parus major)

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Generalization of the experience of programmed control of the knowledge of students in normal anatomy]

Due to increasing significance of application of programmed control of knowledge in the process of teaching students the development and use of such method has been undertaken at the Department of Normal Anatomy of the Pavlov First Medical Institute since 1968 for examining students of the first and second year. The method was used in combination with a usual traditional form of examining. Rapid "selection" of students satisfactorily prepared for further talk at the examination, objectivity of the mark and determination of questions which should be paid special attention at the second half of the examination are positive sides of the method. The article presents tables with results of programmed control of knowledge in anatomy of students of the first and second years of medical and stomatological faculties for the last 3 years.     

Effect of O-methylhydroxylamine on extracellular phage cd]

Study was made of lethal and mutagenic effect of 1 M and 0,5 M O-methylhydroxylamine (OMHA) on extracellular phage Sd. The correlation between chemical changes of the genome and the degree of phage inactivation under the action of OMHA has been established within the range of studied pH (4,5-7,0) of the reaction medium. OMHA in activates the phage at the highest rate at pH 5,0, which agrees with chemical data indicating that the total rate of OMHA modification of cytidine units is maximal at this pH. Inactivation curves of OMHA-treated phage are single-hit at pH investigated, but have a small initial shoulder; at pH 5,0 and 4,5 inactivation curves consist of two exponents, the second exponent having the smallest slope, that is the phage is characterized by an increased resistance to OMHA at this section. The increased phage resistance can be explained by transforming the original product IV (cross-linked with protein) into the product II (N4-methoxy-6-methoxyamine-5,6-dihydrocytidine) which can be repaired in contrast to IV. OMHA has a high mutagenic effect on phage Sd. Under optimal conditions (at pH 4,5) the mutagen induces plaque mutants (up to 6%) among survived phages. The data obtained correlate with the fact that with decreasing pH (from 5,0 to 4,5) the ratio of the "mutagen" unit - N4-methoxycytidine (product III) to the "inactivating" one (product II) increases. The curves of mutation induction under the action of OMHA have a characteristic form with the initial linear section and the maximum or the plateau similar to mutation curves to be observed under the action of radiation and chemical agents.     

New conjugates of antitumor antibiotic doxorubicin with water-soluble galactomannan: synthesis and biological activity

New water-soluble conjugates in the form of Schiff bases (DGM-1 and DGM-2) were prepared by the interaction of water-soluble periodate-oxidized galactomannan with doxorubicin or N-(L-lysyl)doxorubicin, respectively. The water-soluble galactomannan (DAVANAT a commercial product of Pro-Pharmaceuticals company) was obtained by partial acidic hydrolysis of high-molecular-mass galactomannan from Cyamopsis tetragonoloba (guar gum) seeds. The conjugate stability was studied in aqueous solutions. The DGM-1 antiproliferative activity was comparable with that of doxorubicin on three models: cell lines of murine melanoma B 16-F1, human breast cancer MCF-7 (HTB-22), and human colon cancer HT-29 (HTB-38). DGM-2 was poorly active in all the three tests. DGM- 1 can thus be regarded as a high-molecular-mass depot form of doxorubicin.     

ONTOGENETIC NICHE SHIFT IN THE BRACHIOPOD TEREBRATALIA TRANSVERSA: RELATIONSHIP BETWEEN THE LOSS OF ROTATION ABILITY AND ALLOMETRIC GROWTH

Abstract: Many articulated brachiopods experience marked life habit variations during ontogeny because they experience their fluid environment at successively higher Reynolds numbers, and they can change the configuration of their inhalant and exhalant flows as body size increases. We show that the extant brachiopod Terebratalia transversa undergoes a substantial ontogenetic change in reorientation governed by rotation around the pedicle. T. transversa′s reorientation angle (maximum ability to rotate on the pedicle) decreases during ontogeny, from 180 degrees in juveniles to 10–20 degrees in individuals exceeding 5 mm, to complete cessation of rotation in individuals larger than 10 mm. Rotation ability is substantially reduced after T. transversa achieves the adult lophophore configuration and preferred orientation with respect to ambient water currents at a length of 2.5–5 mm. We hypothesize that the rotation angle of T. transversa is determined mainly by the position of ventral and dorsal points of attachment of dorsal pedicle muscles relative to the pedicle. T. transversa shows a close correlation between the ontogenetic change in reorientation angle and ontogeny of morphological traits that are related to points of attachment of dorsal pedicle muscles, although other morphological features can also limit rotation in the adult stage. The major morphological change in cardinalia shape and the observed reduction of rotation affect individuals 2.5–10 mm in length. The position of ventral insertions of dorsal pedicle muscles remains constant, but contraction of dorsal pedicle muscles is functionally handicapped because dorsal insertions shift away from the valve midline, rise above the dorsal valve floor, and become limited by a wide cardinal process early in ontogeny (<5 mm). The rate of increase of cardinal process width and of distance between dorsal pedicle muscle scars substantially decreases in the subadult stage (5–10 mm), and most of the cardinalia shell traits grow nearly isometrically in the adult stage (>10 mm). T. transversa attains smaller shell length in crevices than on exposed substrates. The proportion of small‐sized individuals and population density is lower on exposed substrates than in crevices, indicating higher juvenile mortality on substrates prone to grazing and physical disturbance. The loss of reorientation ability can be a consequence of morphological changes that strengthen substrate attachment and maximize protection against biotic or physical disturbance (1) by minimizing torques around the pedicle axis and/or (2) by shifting energy investments into attachment strength at the expense of the cost involved in reorientation.