Gromochytrium mamkaevae gen. & sp. nov. and two new orders: Gromochytriales and Mesochytriales (Chytridiomycetes).

During the last decade several new orders were established in the class Chytridiomycetes on the basis of zoospore ultrastructure and molecular phylogeny. Here we present the ultrastructure and molecular phylogeny of strain x-51 CALU - a parasite of the alga Tribonema gayanum, originally described as Rhizophydium sp. based on light microscopy. Detailed investigation revealed that the zoospore ultrastructure of this strain has unique characters not found in any order of Chytridiomycetes: posterior ribosomal core unbounded by the endoplasmic reticulum and detached from the nucleus or microbody-lipid complex, and kinetosome composed of microtubular doublets. An isolated phylogenetic position of x-51 is further confirmed by the analysis of 18S and 28S rRNA sequences, and motivates the description of a new genus and species Gromochytrium mamkaevae. The sister position of G. mamkaevae branch relative to Mesochytrium and a cluster of environmental sequences, as well as the ultrastructural differences between Gromochytrium and Mesochytrium zoospores prompted us to establish two new orders: Gromochytriales and Mesochytriales.

[Phenomenon of ischemic steal syndrome in patients with different arteriovenous fistulas for hemodialysis and its surgical correction].

Patients with arteriovenous fistulas (648 cases) were examined for hemodialysis. The ischemic steal syndrome was detected in 47 patients and it was associated with vascular access for hemodialysis. A frequency of given complication was studied with correlation of the type of vascular access. The data of clinical and instrumental examination were described. It was revealed, that the development of steal syndrome was influenced by the blood circulation volume velocity on fistulas. Different reconstructive operations were performed on 42 patients in order to save the access for hemodialysis and eliminate the ischemia. The ligation of fistula was carried out for 5 patients. The survival of arteriovenous fistulas after reconstructive operations was till 46 months during the period of follow-up study.

[Hemodynamic abnormalities in different kind of arteriovenous access for hemodialysis].

On the basis of examination of 35 dialytic patients, who had clinical findings of progressed chronic cardiac insufficiency against the background of the large arteriovenous shunt through existing vascular access, the authors show the complications. The volume of blood circulation along the arteriovenous fistula, which was more than 30% of cardiac output, caused dilatation of heart cavities with cardiac decompensation. If the largest potency to volume remodeling of native proximal arteriovenous fistulas is taken into account, this kind of access could cause hemodynamic abnormalities more often than others (in 22 (62.9%) of patients). The best primary survival was demonstrated by arteriovenous shunts (87.1%) during 2 years. However, long-term survival of native arteriovenous fistulas dramatically outperformed the other kinds of accesses. The choice of constant vascular access for hemodialysis is an important and difficult task in chronic renal disease of V degree patients.

Preliminary observations on the ultrastructure of mitosis in choanoflagellates.

Mitotis in the choanoflagellate Monosiga sp. has been studied by electron microscopy for the first time based on serial sections of metaphase and anaphase. The dense metaphase plate is formed by chromosomes at the centre of the nucleus. Spindle poles are located at the opposite sides of this plate. The nuclear envelope is intact except for fenestrae at the poles through which the spindle microtubules from the MTOCs penetrate. The MTOC is formed by the entire flagellar apparatus of the interphase cell, often with an axoneme lying in cytoplasm. At anaphase, the chromosomes move to the poles with different speeds and the nuclear envelope fragments and disappears.

Comparative morphology of kinetoplastids.

The common structural plan of bodonids, cryptobiids and trypanosomatids permits placing them in one phylum Kinetoplastidae. Analysis of evolutionary changes in the initial "bodonid" structural plan in separate groups within the Kinetoplastidae, illustrated by an evolutionary series of homologous characters, enables us to conclude that the cryptobiids occupy an intermediate position in kinetoplastid evolution between the free-living bodonids and Trypanosoma spp from lower vertebrates and can be considered to be potential ancestors of the latter.

[Phagocytosis and endocytosis in the colorless flagellate Thaumatomonas lauterborni]. / Fagotsitoz i éndotsitoz u bestsvetnogo zhgutikonostsa Thaumatomonas lauterborni.

Phago- and endocytosis have been studied in the colourless flagellate T. lauterborni using electron microscope. The coated pits are formed on the dorsal surface of the cells and in the flagellar pocket; then they are transformed into coated vesicles and transported into the ventral part of the cell loosing their clathrin coat. The storing of small vesicles in the ventral groove region is constant. To begin to feed a flagellate stops and produces within several seconds long ramified filopodia from the ventral groove. These filopodia serve to phagocyte bacteria. Small ventral vesicles represent the membrane pull which is necessary for a quick formation of the vast surface of filopodia. By means of peroxidase reaction in was shown that these vesicles were of endocytotic origin, rather than being the product of the Golgi apparatus functioning.

[The adhesive properties of meningococci from serogroups A, B and C]. / Adgezivnye svoistva meningokokkov serogrupp A, B i C.

The adhesive properties of 261 meningococcal strains have been studied by the methods of the hemagglutination test, the test of adhesion on buccal epithelial cells and electron microscopy. The study has revealed that adhesive properties can be observed in the strains of all groups under study (A, B and C) isolated from patients and carriers, including those isolated from the nasopharynx, blood and liquor, adhesive properties occurring in newly isolated strains with greater frequency than in museum ones. The simultaneous use of all three above-mentioned methods increases the possibility of the detection of meningococcal strains with adhesive activity.

[Hydrodynamic investigations of the current mechanical artificial heart valves]. / Gidrodinamicheskie issledovaniia sovremennykh mekhanicheskikh iskusstvennykh klapanov serdtsa.

The work presents results of comparative investigations of the integral hydrodynamic characteristics of the best for today domestic mechanical heart valve (MHV) Medinzh-2 (MI-2) and the turn-disk domestic MHV--LIKS-2, EMIKS (E) and foreign MHV--Medtronic-Hall, Bjork-Shiley (BS), Sorin (SO) and bicuspid valves--St. Jude Medical (SJ), Carbomedics in the stationary and in the pulsatile flows. It was found that according to the main hydrodynamic characteristics including the outlet flow structure, MHV MI-2 was substantially superior to MHV E, BS and SO, and by certain characteristics it approximated to the best foreign MHV SJ. Like all mechanical heart valves, the valve MI-2 disturbs the uniformity of the inlet flow and forms a complex non-stationary flow with detached zones, areas of great shear stresses, with vortex structures of different types, and hence the task of hydrodynamic optimization of its construction is thought to become actual. The comparison of clinical parameters of work of the valve MI-2 with its hydrodynamic characteristics confirms its high hemodynamic effectiveness and thrombo-resistance in patients at long-term periods of follow-up, taking into account the adequate correction of disbalance of hemostasis.

[The influence of hereditary thrombophilic mechanisms on the degree of permanent intravascular coagulation in patients with artificial heart valves]. / Vliianie nasledstvennykh trombofilicheskikh mekhanizmov na stepen' postoiannogo vnutrisosudistogo svertyvaniia u bol'nykh s iskusstvennymi klapanami serdtsa.

The genotyping of 40 patients with artificial heart valves (AHV) was performed after prosthesis of the mitral and aotic valves with bicuspid AHV (Medinzh-2 and CarboMedics). The patients took phenylin and varfarin. The patients' genotype was estimated by the thrombophylic genes: factor V Leiden (FVL), prothrombin G20210A, methylene tetrahydrofolate reductase C677T, G/A--455FGB, 4G/5G PAI-1, PI A1/A2 GPIIIa. The genes determining the thrombocytic activity or the vascular wall state substantially influence the third degree of the intensity of the permanent intravascular coagulation (PIC-3) independent of the degree of correction of hemostasis of oral anticoagulants. The addition of anti-aggregants to therapy is the only that can normalize functional activity of thrombocytes in patients with AHV having such defects. The laboratory detection of the genetic defects is of great practical importance for the determination of risk groups of formation of PIC-3 and the strategy of antithrombotic protection of patients with AHV.

Cyst formation in a freshwater strain of the choanoflagellate Desmarella moniliformis Kent.

Cyst formation in a freshwater strain of the colonial freshwater choanoflagellate Desmarella moniliformis Kent (Protozoa: Choanoflagellida) has been studied with light and electron microscopy for the first time. Batch cultures inoculated with motile vegetative cells start to produce cysts within 3 days during the exponential phase of growth. Cyst production proceeds until in late stationary phase there is a preponderance of cysts. Transfer of cysts to fresh medium results in limited excystment. Encystment involves the production of electron-dense fibrillar wall material, firstly around the neck of the cell and then around the posterior end. As the wall material is deposited the neck of the cell elongates and the dictyosome rotates from the horizontal to vertical plane. The number of mitochondrial profiles seen in individual sections of cells increases. Finally the neck of the cell is retracted, the flagellum and collar tentacles are withdrawn, and the bottom of the neck of the cyst wall is sealed with a diaphragm of wall material. Excystment, which has not been observed directly, appears to involve the disruption of the wall at the base of the neck, the remainder of the cyst wall remains intact. Comparisons are made between encystment in Desmarella and cyst development in other protists.