Clonogenic stromal cell count in the bone marrow of mice

The number of fibroblast colonies in bone marrow cultures depends on FCFC concentration in explanted cells and FCFC cloning efficiency. For mouse bone marrow the efficiency of fibroblast colony formation increases in the presence of the feeder (irradiated bone marrow of spleen cells). Colony-stimulating feeder activity does not depend on the presence of phagocytic and stromal cells in the feeder cell population. Trypsinization of the bone marrow leads to the release of additional FCFC and the increase of their concentration in bone marrow cell suspensions.     

The genotyping of the West Nile virus in birds in the far eastern region of Russia in 2002-2004

Samples from 20 species of trapped and dead birds were collected in the Far Eastern Region in 2002-2004 and were analyzed by the anti-WNV MAb-modified immunoenzyme assay for antigen detection and RT-PCR for viral RNA detection. Five positive samples from cinereous vultures (Aegypius monachus) and two positive samples from cattle egret (Bubulcus ibis) were found in both tests. The sequencing of the 322 bp fragments of protein E gene showed 99-99.67% homology with the strain WNV/LEIV-VlgOO-27924 of the WNV isolated in Volgograd, Russia, 2000. Additionally, five positive samples from birds (Pica pica, Corvus macrorhynchos, Larus crossirostris, Parus minor, Emberiza spodocephala) collected in autumn 2004 were found during screening with anti-WNV MAb-modified ELISA. These results confirm that the WNV is circulating in the Far Eastern Region of Russia and outbreaks of WN fever in humans may be possible. This demonstrates that the genotype 1a of the West Nile virus could spread in the southern regions of the Far East by migrating birds and introduction of the WNV into other southern regions of the Asian part of Russia are probably.     

Cortical potential imaging using L-curve and GCV method to choose the regularisation parameter

Background

The electroencephalography (EEG) is an attractive and a simple technique to measure the brain activity. It is attractive due its excellent temporal resolution and simple due to its non-invasiveness and sensor design. However, the spatial resolution of EEG is reduced due to the low conducting skull. In this paper, we compute the potential distribution over the closed surface covering the brain (cortex) from the EEG scalp potential. We compare two methods – L-curve and generalised cross validation (GCV) used to obtain the regularisation parameter and also investigate the feasibility in applying such techniques to N170 component of the visually evoked potential (VEP) data.

Methods

Using the image data set of the visible human man (VHM), a finite difference method (FDM) model of the head was constructed. The EEG dataset (256-channel) used was the N170 component of the VEP. A forward transfer matrix relating the cortical potential to the scalp potential was obtained. Using Tikhonov regularisation, the potential distribution over the cortex was obtained.

Results

The cortical potential distribution for three subjects was solved using both L-curve and GCV method. A total of 18 cortical potential distributions were obtained (3 subjects with three stimuli each – fearful face, neutral face, control objects).

Conclusions

The GCV method is a more robust method compared to L-curve to find the optimal regularisation parameter. Cortical potential imaging is a reliable method to obtain the potential distribution over cortex for VEP data.

     

Influence of digital dermatitis and sole ulcer on dairy cow behaviour and milk production

The aim of the study was to investigate whether the presence of digital dermatitis (DD) and sole ulcer (SU) in dairy cows was associated with changes in behaviour and milk production. Swedish Red and Swedish Holstein cows (mostly in the first to second lactation) were housed in a cubicle system with automatically scraped passageways. After maintenance claw trimming of all the cows in the herd, 10 cows with DD and 10 cows with SU were selected. For each DD- or SU-affected cow, a healthy control cow, matched according to breed, age, parity and lactation stage, was selected. The behaviour of each of the 20 focal cows was observed for 1 h during 2 to 3 weeks after claw trimming (WACT; period 1) and for 1 h during 5 to 6 WACT (period 2). Milk production parameters: energy-corrected milk (ECM), fat and protein percentages and somatic cell counts (SCCs) were recorded once monthly. Lameness was scored once at the start of the study and cows with SU and DD showed more score 2 lameness (42% v. 31%) than the healthy cows (12%). Most differences in behaviour were found during 2 to 3 WACT when DD- and SU-affected cows were lying less (P = 0.001 and P = 0.012, respectively) than healthy cows. Ruminating while standing was performed more in DD-affected cows (P < 0.001) and tended to be performed more in SU-affected cows (P = 0.079) than their controls. Vigilance was performed more in DD- and SU-affected cows than in healthy cows (P < 0.001 and P = 0.047). Cows with DD produced approximately 5.5 kg less ECM per day both at 2 to 3 WACT (P = 0.022) and at 5 to 6 WACT (P = 0.017) than healthy cows, whereas SU-affected cows tended to produce less ECM at 5 to 6 WACT (P = 0.059). No differences in milk fat and protein or SCC were found. It may be concluded that DD-affected cows showed a stronger behavioural response to the claw disease than the SU-affected cows. This shows the importance of regular claw checking and claw trimming of the cows in order to avoid the negative effects on behaviour and milk production.     

Influence of the shape of the cross section of a plasma-dielectric interface on the dispersion properties of high-frequency azimuthal surface modes

Theoretical study of the propagation of a packet of surface electromagnetic surface waves with a zero axial wavenumber in a circular-cross-section cylindrical metal waveguide within the frequency range that is higher than upper hybrid resonance is carried out. The waveguide is partially filled by plasma and immersed into axial magnetic field. The cross section of the plasma column is assumed to differ from circular shape. The effect of this shape on the dispersion properties of azimuthal surface modes is investigated by the method of successive approximations. The fields of the waves and their eigenfrequencies are determined up to terms of the second order in the deviation of the plasma cross section shape from the ring one. The correction to the eigenfrequency of azimuthal surface modes caused by this feature of the plasma column section is proved to increase with decreasing the external magnetic field and increasing the value of the dielectric constant of the dielectric, that separates the plasma from the metal wall of the waveguide. The spectral composition of the wave packet, in the form of which these modes propagate, is studied. The amplitudes of the satellite harmonics of these modes are found to increase with increasing the plasma density and decreasing the external magnetic field.     

Clonal nature of fibroblast colonies formed by stromal bone marrow cells in culture

The clonal nature of CFUf-derived fibroblast colonies was tested in mixed cultures of CBA and CBAT6T6 bone marrow cells. Inoculation of marrow cell suspensions into flasks coated with poly-I-lysin has proved that no stromal aggregates were present among cells subjected to explantation. Marrow cell cultures depleted of macrophages and myeloid cells were used for chromosome analysis. The coincidence of karyotypes within a stromal colony was found in mixed cultures, which proves that CFUf-derived fibroblast colonies are cell clones.     

Long-term storage of industrial microbial strains

Morphofunctional characteristics of industrial microorganisms belonging to different genera, species, and strains were investigated after 15 to 20 years of storage in liquid nitrogen. The taxonomic position of microorganisms, the cell physiological state prior to storage, and the cryoconservation regime were found to affect microbial cryoresistance. Protective media, density of cell suspensions, freezing rate, and heating temperature are the parameters important for development of efficient technologies for cryoconservation of industrial microorganisms at ?196°C.