Initial Cell Volume Research Articles

Study of microstructure, magnetic and gas sensing properties of porous Ni0.4+xZn0.6-xCeyFe2-yO4 magnetic nanoparticles

The spinel ferrite systemsNi0.4+xZn0.6−xCeyFe2−yO4 (0≤x+y≤0.3) were synthesized by a modified glycol-thermal technique. X-ray diffractometer (XRD) confirmed formation of single phase cubic spinel structure with average crystallite sizes 8–21 nm. The crystallite sizes were found to be in agreement with the particle sizes obtained from the high resolution transmission electron microscopy (HRTEM) indicating formation of single domain nanoparticles. Scanning electron microscopy (SEM) showed a homogeneous spread of semi-spherical nanoparticles. Brunauer-Emmett-Teller (BET) revealed specific surface area ranging between 64 and 108 m2/g, while Barrett-Joyner-Halenda (BJH) showed the pore sizes varying between 48 and 126 nm. Cation distribution obtained from Rietveld refinement revealed all Ce3+ occupied B- sites whilst Ni2+, Zn2+, Fe3+ occupied both A and B sites. Magnetization measurements were performed using the vibration samples magnetometer (VSM). The saturation magnetization varied between 51 and 60 emu/g, while the coercivity dropped from 114 to 89Oe. The remnant magnetization varied between 3 and 12 emu/g. A correlation was observed between the saturation magnetization and the effective magnetic moments confirming cation distribution to be reliable. A strong correlation between initial susceptibility and unit cell volume was found. The crystallite sizes varied inversely with initial magnetic susceptibility. The magnetic characteristics of presented materials make them useful in high frequency device applications and has potential use as contrast agent in magnetic resonance imaging (MRI). 57Fe Mössbauer spectroscopy revealed the strengthening of ferromagnetic coupling. Gas sensing tests revealed a decrease in sensing response with the transition from paramagnetic state to ferromagnetic state. The Ni0.4Zn0.6Fe2O4 sample showed the best sensing response to SO2 at 100 °C compared to CO gas. However, at 150 °C the sample was more sensitive to CO gas than SO2 gas.

First principle investigation on properties of MnO2 as an electrode material for Li, Na, Mg, and Al -ion batteries

This study uses noble evaluations in Density Functional Theory (DFT) framework to investigate the structural, electrochemical, magnetic, and electrical properties of AMn2O4 (A = Li, Na, Mg, and Al) cathode materials for various metal-ion batteries. The calculations are performed by four DFT methods (GGA/+U, LSDA/+U). Considering volume change Both GGA and LSDA methods showed that NaMn2O4 had the highest and AlMn2O4 had the lowest volume reduction, caused by electronegativity of Al and the initial unit cell volume. The cell voltages were calculated with two different approaches called as internal and Fermi energy. It was concluded that the probable low cycle-ability of this family can be attributed to remarkable alteration of magnetic moment of manganese transition metal during extraction/insertion of intercalating ions. The electrical properties of AMn2O4 materials were investigated evaluating BGs and electrical rate-capability. For each material two kinds of band-gap (BG) and two criterions for rate-capability were considered, i.e. ILBG/ELBG, and Delta/CCTB, respectively. The BG evaluation showed that all the considered materials have appropriate conductivity. Both of the evaluated Delta and CCTB approaches predicted high rate-capability for the AMn2O4 materials. Our calculations demonstrated that MnO2 is a suitable and highly considerable cathode material for the Li and beyond-Li -ion batteries.

Structural and magnetic characterization of Co2+ substituted Ni-Zn ferrite nanoparticles synthesized by refluxing co-precipitation and their potential application as gas sensors

This work investigates the effect of Co2+ content on the structural, magnetic, and gas sensing properties of Ni0.3Zn0.7-xCoxFe2O4 (x=0.00, 0.05, 0.15, 0.25, 0.35) nanoferrites synthesized by refluxing co-precipitates of metal chlorides. X-ray diffraction and electron microscopy were used to study the structure and morphological aspects of the materials. X-ray diffraction (XRD) patterns revealed single-phase nanomaterial with shrinking lattice constants from 8.41 to 8.38 Å with increasing Co2+ content. The crystallite sizes varied slightly between 9.95 and 10.06 nm. The vibrating sample magnetometer (VSM) was used to extract information of the magnetization of the materials at room temperature. Saturation magnetization increased from 39.5 to 48.5 emu/g from x = 0 to 0.25 and dropped at x = 0.35 to 46.2 emu/g. Furthermore, the coercivity, effective anisotropy constant and remnant magnetization increased from 170 to 400 Oe, 696 to 1925 erg/Oe, and 1.15 to 2.72 emu/g respectively. A distinct correlation between the inverse initial magnetic susceptibility and unit cell volume of the materials was found. Room temperature 57Fe Mössbauer spectra revealed a magnetic transition from paramagnetic to ordered magnetic phase with increased Co2+ content. Except for sample with x = 0 and 0.15, where suspected co-existence of Fe3+ and Fe2+ was observed Fe3+ ions were observed. Zn2+ ions were found to largely occupy the B sites. Specific surface area and the average pore size distribution increased from 61 – 85 m2 g−1 and 22 – 25 nm respectively, with the addition of Co2+ content. The composition x= 0 showed exceptional response to propanol suggesting good suitability for sensor fabrication. All samples revealed the selectivity preferences in the order of propanol > ethanol > methanol.

Asymptotic behavior of two competing cancer cell migration mechanisms driven by interstitial fluid flow

In this paper, we will investigate two competing mechanisms of cancer cell migration, which are driven by interstitial fluid flow and satisfy the suitable boundary conditions in two different radial symmetry domains, respectively. For both mechanisms, we will study their asymptotic behavior in different environments with low and high initial cell volume fraction separately. More precisely, our first result is to analyze the convergence of the solution to a downstream-dominated steady state over time in BR(0)﹨Bρ(0)⊂Rd(d≥2) with 0<ρ<R when the initial unit volume fraction is sufficiently low, while our second result is to investigate the convergence of the solution to an upstream-dominated steady state in BR(0)⊂Rd(d≥2) when the initial cell volume fraction is high enough.

Metal Halide Perovskites Demonstrate Radiation Hardness and Defect Healing in Vacuum.

Herein, we subject formamidinium lead iodide films to oxygen-containing gases (flowing O2 or free diffusion of lab atmosphere), inert gases (flowing He, Ar, or N2), and vacuum. Our films are irradiated by Cu Kα X-rays and held at 75 °C while X-ray diffraction is recorded. Under all gas conditions, we observe a reproducible 1.1 ± 0.5 Å3 perovskite lattice contraction from an initial unit cell volume of 256.5 ± 0.8 Å3 concurrent with continuous perovskite loss and lead iodide growth. Oxygen-containing gases increase the reaction rates without materially altering perovskite structural changes. Under the same temperature and irradiation conditions in vacuo, a self-healing reaction is observed, exhibited by a reproducible (0.9 ± 0.3 Å3) lattice expansion and stabilization of the perovskite. Interactions between the perovskite, defects, and minority phases are simulated by generalized gradient approximation Perdew-Burke-Ernzerhof (GGA-PBE) density functional theory. Lattice contraction indicates an increase in the concentration of Schottky defects─pairs of formamidinium and iodine vacancies. Under irradiation in every atmospheric condition, a solid solution of Schottky defects with a concentration of several percent diffuses and precipitates forming lead iodide and consuming the defects. In the presence of ionized gases, this framework is modified to include the continual loss of formamidinium and iodine ions from the perovskite forming Schottky defects.

Mathematical Analysis of Two Competing Cancer Cell Migration Mechanisms Driven by Interstitial Fluid Flow

Recent experimental work has revealed that interstitial fluid flow can mobilize two types of tumor cell migration mechanisms. One is a chemotactic-driven mechanism where chemokine (chemical component) bounded to the extracellular matrix (ECM) is released and skewed in the flow direction. This leads to higher chemical concentrations downstream which the tumor cells can sense and migrate toward. The other is a mechanism where the flowing fluid imposes a stress on the tumor cells which triggers them to go in the upstream direction. Researchers have suggested that these two migration modes possibly can play a role in metastatic behavior, i.e., the process where tumor cells are able to break loose from the primary tumor and move to nearby lymphatic vessels. In Waldeland and Evje (J Biomech 81:22–35, 2018), a mathematical cell–fluid model was put forward based on a mixture theory formulation. It was demonstrated that the model was able to capture the main characteristics of the two competing migration mechanisms. The objective of the current work is to seek deeper insight into certain qualitative aspects of these competing mechanisms by means of mathematical methods. For that purpose, we propose a simpler version of the cell–fluid model mentioned above but such that the two competing migration mechanisms are retained. An initial cell distribution in a one-dimensional slab is exposed to a constant fluid flow from one end to the other, consistent with the experimental setup. Then, we explore by means of analytical estimates the long-time behavior of the two competing migration mechanisms for two different scenarios: (i) when the initial cell volume fraction is low and (ii) when the initial cell volume fraction is high. In particular, it is demonstrated in a strict mathematical sense that for a sufficiently low initial cell volume fraction, the downstream migration dominates in the sense that the solution converges to a downstream-dominated steady state as time elapses. On the other hand, with a sufficiently high initial cell volume fraction, the upstream migration mechanism is the stronger in the sense that the solution converges to an upstream-dominated steady state.

The nature of cell volume sensor in shrinkage‐induced apoptosis

Potassium loss and persistent shrinkage have been both implicated in apoptosis, but their relationship and respective roles remain obscure. We approached this problem by clamping intracellular sodium and potassium in HeLa, MDBK or MDCK cells by a combination of ionophores and ouabain. Although ionophores cause significant cell swelling, the initial volume can be restored and further reduced by applying external sucrose. We showed that swollen cells treated with ionophores remain viable for at least 4–8 hours without developing any signs of apoptosis. Application of sucrose and the resulting shrinkage caused volume‐dependent intrinsic apoptosis with all its classical features: inversion of phosphatidylserine, caspase activation, cytochrome c release from mitochondria. Furthermore, overexpression of Bcl‐2 prevents mitochondrial loss of cytochrome c in shrunken cells. All these responses occurred to approximately the same degree regardless of whether the cells were kept in a high potassium/zero sodium or in a high sodium/zero potassium buffer, with only a slight enhancement under potassium‐free conditions. However, apoptosis induced by protein kinase inhibitor staurosporine in ionophore‐treated and swollen cells was strongly inhibited by as little as 5 mM potassium. Addition of 50 mM sucrose to restore the initial cell volume eliminated potassium dependence of staurosporine‐induced caspase activation. We have eliminated potassium as a stimulus in shrinkage induced apoptosis and are left with the choice between macromolecular crowding and cytoskeleton, which according to our unconfirmed preliminary data may be cytoskeleton. Thus, our results show that: (1) persistent shrinkage (presumably mediated through macromolecular crowding) acts as a direct proapoptotic signal independently of potassium; (2) strong potassium dependence of caspase activation is only observed in swollen cells with reduced cytoplasmic density.

A study of the osmotic characteristics, water permeability, and cryoprotectant permeability of human vaginal immune cells

Cryopreservation of specimens taken from the genital tract of women is important for studying mucosal immunity during HIV prevention trials. However, it is unclear whether the current, empirically developed cryopreservation procedures for peripheral blood cells are also ideal for genital specimens. The optimal cryopreservation protocol depends on the cryobiological features of the cells. Thus, we obtained tissue specimens from vaginal repair surgeries, isolated and flow cytometry-purified immune cells, and determined fundamental cryobiological characteristics of vaginal CD3+ T cells and CD14+ macrophages using a microfluidic device. The osmotically inactive volumes of the two cell types (Vb) were determined relative to the initial cell volume (V0) by exposing the cells to hypotonic and hypertonic saline solutions, evaluating the equilibrium volume, and applying the Boyle van't Hoff relationship. The cell membrane permeability to water (Lp) and to four different cryoprotective agent (CPA) solutions (Ps) at room temperature were also measured. Results indicated Vb values of 0.516 V0 and 0.457 V0 for mucosal T cells and macrophages, respectively. Lp values at room temperature were 0.196 and 0.295 μm/min/atm for T cells and macrophages, respectively. Both cell types had high Ps values for the three CPAs, dimethyl sulfoxide (DMSO), propylene glycol (PG) and ethylene glycol (EG) (minimum of 0.418 × 10−3 cm/min), but transport of the fourth CPA, glycerol, occurred 50–150 times more slowly. Thus, DMSO, PG, and EG are better options than glycerol in avoiding severe cell volume excursion and osmotic injury during CPA addition and removal for cryopreservation of human vaginal immune cells.

Reciprocal space mapping of silver nanoparticle array re-assembly and oxidation

Self-assembled metal oxide nanoparticle layers have attracted much attention recently due to potential applications in sensors. Here we report on a UV/ozone-driven re-assembly and oxidation of a self-assembled silver nanoparticle bilayer deposited by a modified Langmuir-Schaefer technique that was probed in-situ by simultaneous measurements of the small- and wide-angle X-ray scattering at grazing incidence (GISAXS, GIWAXS). The experiments were performed at BL23A endstation of NSRRC, Taiwan. Four distinct stages of the system response to the UV/ozone treatment were identified. In the first stage 0-120 s, a gradual extinction of Bragg rods and the nanoparticle short-range order due to a gradual surfactant removal is observed in GISAXS that is connected with an array densification and order improvement obeying the paracrystal model in the shrinking self-assembled regions. In the second stage 120-360 s, the original self-assembly goes to a total extinction while the integral intensity of Ag 111 diffraction in GIWAXS starts to decrease, suggesting the total surfactant removal. No nanoparticle short-range order is observed in stage III 360-730 s where AgO monoclinic phase due to the nanoparticle surface oxidation appears and pure Ag phase disappears. The initial AgO unit cell volume corresponding to the unstrained phase gradually expands by 4.6 % to the end of stage III. In stage IV 730-2000 s (end of measurements), new Bragg rods appear in GISAXS, suggesting a nanoparticle agglomeration with a typical correlation length of approximately 240 nm that was confirmed by ex-situ atomic force microscopy. The agglomeration does not reach saturation even after 2000 s while the AgO phase remains stable. These results have direct implications for tailored preparation of advanced sensors based on metal oxide nanoparticles. The work was supported by the projects APVV-0308-11, VEGA 2/0041/11, SAS-NSC JRP 2011/05, SAS-TUBITAK JRP 2013/6, COST MP1203 and COST CM1101.

Possible causes of apoptotic volume decrease: an attempt at quantitative review

Cell shrinkage and dehydration are essential characteristics of apoptosis, and loss of as much as half of the initial cell volume is not uncommon. This phenomenon is usually explained by efflux of K(+) and Cl(-). We reexamine this hypothesis on the basis of the available data for ion concentrations and the requirements for osmotic equilibrium and electroneutrality. In addition to ion loss, we discuss the possible impacts of several other processes: efflux of low-molecular-weight osmolytes, acidification of the cytosol, effects of water channels and pumps, heterogeneity of intracellular water, and dissociation of apoptotic bodies. We conclude that most mammalian cells are theoretically capable of reducing their volume by 15-20% through ion loss or a decrease in cytosolic pH, although, in reality, the contribution of these mechanisms to apoptotic shrinkage may be smaller. Transitions between osmotically active and inactive water pools might influence cell volume as well; these mechanisms are poorly understood but are amenable to experimental study. Dissociation of apoptotic bodies is a separate mechanism of volume reduction and should be monitored closely; this can be best achieved by measurement of intracellular water, rather than cell volume.

Red Cell Volume Expansion at Altitude

Altitude acclimatization is associated with a rapid increase in hematocrit. The time course and the contribution of the red cell volume expansion are not clear. The purpose of the present meta-analysis was to explore how much altitude exposure is required to induce polycythemia in healthy lowlanders. A systematic review was performed of 66 published articles (including 447 volunteers) identified through literature search. We performed a mixed-model random-effects meta-analysis and a Monte Carlo simulation on the extracted data. The following results were obtained in this study: 1) the red cell volume expansion for a given duration of exposure is dependent on altitude (P < 0.0001), that is, that the increase in red cell volume was accelerated at higher altitudes; and 2) the extent of the erythropoietic response depends on the initial red cell volume (P < 0.0001). It seems that exposure time must exceed 2 wk at an altitude of more than 4000 m to exert a statistically significant effect. At lower altitudes, longer exposure times are needed with altitudes lower than 3000 m not yielding an increase within 4 wk. Red cell volume response to hypoxia is generally slow, although it accelerates with increasing altitude. This, in combination with a dependency on initial red cell volume, suggests that, for example, athletes may need to spend more time at altitude to see an effect on red cell volume than commonly recommended.

Osmotic fragility of human erythrocytes in vitro using Vipera lebetina venom

The objective of this study was to investigate the in vitro effect of Vipera lebetina venom on human erythrocytes’ osmotic fragility with respect to different venom concentrations, time of incubation with the venom, initial volume of red blood cells, and presence of antivenom. In vitro osmotic fragility of human erythrocytes was determined using Dacie and Lewis method. Osmotic fragility is increased significantly after incubation with the venom at different concentrations. The maximal effect was detected at the venom concentration of 400 μg. Time of incubation with the venom was an important factor in hemolytic process while the initial cell volume has no significant effect. Incubation of envenomed erythrocytes for 120 min with antivenom did not reverse the changes in osmotic fragility induced by the venom. The study suggests that the venom could alter the susceptibility of erythrocytes to hemolysis when subjected to osmotic stress and the degree of hemolysis depends on venom concentration and time of intubation with the venom.

Crystal Structure Changes of LiNi0.5Co0.2Mn0.3O2Cathode Materials During the First Charge Investigated by in situ XRD

The structural changes of Li1-xNi0.5Co0.2Mn0.3O2 cathode material for lithium ion battery during the first charge was investigated in comparison with Li1-xNi0.8Co0.15Al0.05O2 using a synchrotron based in situ X-ray diffraction technique. The structural changes of these two cathode materials show similar trend during first charge: an expansion along the c-axis of the unit cell with contractions along the a- and b-axis during the early stage of charge and a major contraction along the c-axis with slight expansions along the a- and b-axis near the end of charge at high voltage limit. In Li1-x Ni0.5Co0.2Mn0.3O2 cathode, however, the initial unit cell volume of H2 phase is bigger than that of H1 phase since the c-axis undergo large expansion while a- and b- axis shrink slightly. The change in the unit cell volume for Li1-xNi0.5Co0.2Mn0.3O2 during charge is smaller than that of Li1-x Ni0.8Co0.15Al0.05O2. This smaller change in unit cell volume may give the Li1-xNi0.5Co0.2Mn0.3O2 cathode material a better structural reversibility for a long cycling life.

Adsorption and degradation of zearalenone by bacillus strains

Two Bacillus strains; Bacillus subtilis 168 and Bacillus natto CICC 24640 separately adsorbed and degraded zearalenone in liquid media, in vitro. Viable, autoclaved (121°C, 20min) and acid-treated cells of both strains separately bound more than 55% of zearalenone (ZEN, 20μg/L) after 30min and 1-h incubation at 37°C under aerobic conditions, and the amount of ZEN adsorbed was dependent on initial cell volume. In addition, ZEN was degraded by the culture extract of both strains. Degradation by B. subtilis 168 and B. natto CICC 24640 culture extract after 24-h aerobic incubation at 30°C was 81% and 100%, respectively. B. natto CICC 24640 culture extract comprehensively degraded ZEN and, for both strains, no oestrogenic ZEN analogues were present. ZEN degradation was accompanied by carbondioxide emission indicating a decarboxylation reaction. ZEN degradation by the salient B. natto CICC 24640 culture extract varied with initial ZEN concentration, incubation time, temperature and pH. Degradation was enhanced by Mn(2+), Zn(2+), Ca(2+) and Mg(2+) but impeded by Hg(2+), Cu(2+), Pb(2+), ethylenediaminetetraacetic acid and 1,10-phenanthroline. The degradation reaction is associated with a metalloproteinase of molar mass in the range 31-43kDa. Overall, the two generally recognised as safe Bacillus strains can, potentially, be utilised for detoxification of zearalenone in food.

Ion channels in volume regulation of clonal kidney cells

Clonal kidney cells (Vero cells) are extensively utilized in the manufacture of biological preparations for disease diagnostics and therapeutics and also in preparation of vaccines. In all cells, regulation of volume is an essential function coupled to a variety of physiological processes and is a topic of interest. The objective here was to investigate involvement of ion channels in the process of volume regulation of Vero cells. Involvement of ion channels in cell volume regulation was studied using video-microscopy and flow cytometry. Pharmacologically unaltered cells of different sizes, which are presumably at different phases of the cell cycle, were used. Ion transport inhibitors altered all phases of regulatory volume decrease (RVD) of Vero cells, rate of initial cell swelling, V(max) and volume recovery. Effects were dependent on type of inhibitor and on cell size (cell cycle phase). Participation of aquaporins in RVD was suggested. Inhibitors decelerated growth, arresting Vero cells at the G(0) /G(1) phase boundary. Electrophysiological study confirmed presence of volume-activated Cl(-) channels and K(+) channels in plasmatic membranes of the cells. Vero cells of all sizes maintained the ability to recover from osmotic swelling. Activity of ion channels was one of the key factors that controlled volume regulation and proliferation of the cells.

Using single cell cultivation system for on-chip monitoring of the interdivision timer in Chlamydomonas reinhardtii cell cycle

Regulation of cell cycle progression in changing environments is vital for cell survival and maintenance, and different regulation mechanisms based on cell size and cell cycle time have been proposed. To determine the mechanism of cell cycle regulation in the unicellular green algae Chlamydomonas reinhardtii, we developed an on-chip single-cell cultivation system that allows for the strict control of the extracellular environment. We divided the Chlamydomonas cell cycle into interdivision and division phases on the basis of changes in cell size and found that, regardless of the amount of photosynthetically active radiation (PAR) and the extent of illumination, the length of the interdivision phase was inversely proportional to the rate of increase of cell volume. Their product remains constant indicating the existence of an 'interdivision timer'. The length of the division phase, in contrast, remained nearly constant. Cells cultivated under light-dark-light conditions did not divide unless they had grown to twice their initial volume during the first light period. This indicates the existence of a 'commitment sizer'. The ratio of the cell volume at the beginning of the division phase to the initial cell volume determined the number of daughter cells, indicating the existence of a 'mitotic sizer'.

Tissue and cellular morphological changes in growth plate explants under compression

The mechanisms by which mechanical loading may alter bone development within growth plates are still poorly understood. However, several growth plate cell or tissue morphological parameters are associated with both normal and mechanically modulated bone growth rates. The aim of this study was to quantify in situ the three-dimensional morphology of growth plate explants under compression at both cell and tissue levels. Growth plates were dissected from ulnae of immature swine and tested under 15% compressive strain. Confocal microscopy was used to image fluorescently labeled chondrocytes in the three growth plate zones before and after compression. Quantitative morphological analyses at both cell (volume, surface area, sphericity, minor/major radii) and tissue (cell/matrix volume ratio) levels were performed. Greater chondrocyte bulk strains (volume decrease normalized to the initial cell volume) were found in the proliferative (35.4%) and hypertrophic (41.7%) zones, with lower chondrocyte bulk strains (24.7%) in the reserve zone. Following compression, the cell/matrix volume ratio decreased in the reserve and hypertrophic zones by 24.3% and 22.6%, respectively, whereas it increased by 35.9% in the proliferative zone. The 15% strain applied on growth plate explants revealed zone-dependent deformational states at both tissue and cell levels. Variations in the mechanical response of the chondrocytes from different zones could be related to significant inhomogeneities in growth plate zonal mechanical properties. The ability to obtain in situ cell morphometry and monitor the changes under compression will contribute to a better understanding of mechanisms through which abnormal growth can be triggered.

19. Intracellular freezing behavior under conditions of altered water permeability and initial cell volume

19. Intracellular freezing behavior under conditions of altered water permeability and initial cell volume

Evaluation of an Automated Ficoll Procedure To Enrich for Mononuclear Cells for Use in Clinical Trials.

Mononuclear cell fraction (MNC) enrichment from hematopoietic progenitor cells (HPC) cells is required for a number of clinical applications. Previously, we have used a manual method for enrichment of these cells. We evaluated an automated procedure for better consistency and patient safety (reduce risk of contamination). We have been using the Sepax (BioSafe) for the past 18 months to process Cord Blood (RBC depletion) before cryopreservation. Since the instrument can also do density gradient enrichment of mononuclear cells, we evaluated the ability to process different sources of hematopoietic progenitor cells (HPC) on the Sepax.Methods: Bone marrow, non-mobilized apheresis and cord blood were evaluated as a source of HPC. Briefly, 100ml of Ficoll solution were added to the chamber of the Sepax disposable. After initiating centrifugation, 50–110 ml of HPC were then overlayed onto the density gradient. The cells were fractionated, mononuclear cell fraction isolated, and then washed three times before final resuspension in 50ml of Saline/5% albumin. In some experiments the HPC were divided into two fractions so that a direct comparison of the Manual vs Automated enrichment procedure could be compared. Finally, a recent publication from Seeger et al (European Heart Journal 28:766, 2007) suggested different density gradient solutions have an effect on MNC enrichment. Therefore, four different brands of density gradient solution (GE Ficoll-Paque Premium, Sigma Histopaque 1077, Accurate Lymphoprep and Lonza Lymphocyte Separation media) were evaluated to determine if there was a differential separation of subsets of cells.Results: The total nucleated cell (TNC), MNC and CD34 recoveries after MNC enrichment were similar for either bone marrow or cord blood HPC comparing the manual procedure and the automated procedure. The TNC and MNC recovery was higher for apheresis products (66% and 69% respectively) than the other two sources of HPC. This most likely reflects the enriched MNC starting population from an apheresis device. We evaluated the TNC and MNC recoveries over a range of initial TNC (7.5–20 × 108 cells) but could not see an effect of either cell number or cell concentration on recoveries. Nor could we see an effect of initial cell volume (50–100 mls) on recovery of cells post processing. Finally, we could not see a difference in either TNC or MNC recovery when the four different sources of density gradient solution were compared.Conclusion: We have shown that the Sepax instrument can be used for enrichment of mononuclear cells from HPC, Marrow, HPC, Apheresis and HPC, Cord. The benefits of an automated system are1.consistency,2.functionally closed system which reduces possibility of contamination3.documentation of run parameters and4.shorter processing time. [Display omitted]

Relationship between the replicative age and cell volume in Saccharomyces cerevisiae.

Reaching the limit of cell divisions, a phenomenon referred to as replicative aging, of the yeast Saccharomyces cerevisiae involves a progressive increase in the cell volume. However, the exact relationship between the number of cell divisions accomplished (replicative age), the potential for further divisions and yeast cell volume has not been investigated thoroughly. In this study an increase of the yeast cell volume was achieved by treatment with pheromone alpha for up to 18 h. Plotting the number of cell divisions (replicative life span) of the pheromone-treated cells as a function of the cell volume attained during the treatment showed an inverse linear relationship. An analogous inverse relationship between the initial cell volume and replicative life span was found for the progeny of the pheromone-treated yeast. This phenomenon indicates that attaining an excessive volume may be a factor contributing to the limitation of cellular divisions of yeast cells.