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PubMed2000

Peripheral blood stem cell mobilization with cyclophosphamide in combination with G-CSF, GM-CSF, or sequential GM-CSF/G-CSF in non-Hodgkin's lymphoma patients: a randomized prospective study.

We designed a randomized, prospective three-arm mobilization study to determine the kinetics of peripheral blood stem cell (PBSC) mobilization in 60 non-Hodgkin's lymphoma (NHL) patients primed with cyclophosphamide (CTX) in combination with granulocyte colony-stimulating factor (G-CSF) (arm A), granulocyte-macrophage (GM)-CSF (arm B) or GM-CSF/G-CSF (arm C). We also compared mobilization and transplant-related toxicities, pre- and post-transplant support and the probability of survival among the three arms. To date, 35 patients have been enrolled in the study; 13 patients have been enrolled in arm A, 10 patients in arm B, and 13 patients in arm C. Successful collection of the target of > or = 2 X 10(6) CD34+ cells/kg in one to four apheresis collections was 10/13, 6/10, and 7/12 in arms A, B, and C, respectively. The differences between arms were not statistically significant. The median time to achieve the target CD34+ cells in patients who successfully mobilized the target CD34+ cells was 3 days, 2 days, and 1 day, in patients in arms A, B, and C, respectively. The time for neutrophil engraftment was 11, 10, and 10 days in arms A, B, and C, respectively. The time for platelet engraftment was 11 days for patients in all arms of the study. Most importantly, no significant differences were observed among the three arms in the duration of neutropenic fever, the extent of mucositis, diarrhea, and nausea/vomiting, or in the number of units of platelets or red cells transfused after transplantation. Risk factors associated with poor mobilization were > or = 3 regimens of chemotherapy prior to mobilization, older age, and disease histology (follicular versus diffuse). Therefore, we conclude that the type of growth factor used for mobilization did not play a major role in the outcome of mobilization and recommend mobilizing NHL patients before they receive multiple regimens of chemotherapy.

Adult↗

PubMed2002

Decreased stroma adhesion capacity of CD34+ progenitor cells from mobilized peripheral blood is not lineage- or stage-specific and is associated with low beta 1 and beta 2 integrin expression.

Molecular mechanisms leading to mobilization of hematopoietic cells from bone marrow (BM) to peripheral blood (PB) involve modulation of adhesion molecule expression on these cells that probably result in changes in adhesion capacity to the microenvironment. However, it is not clear whether these changes involve different stages or lineages of progenitor cells. In this study, we compared the capacity of mature and immature clonogenic progenitor cells from granulocyte colony-stimulating factor (G-CSF)-mobilized PB and normal BM CD34+ cells to adhere to complete marrow stroma. This functional capacity was assessed concurrently with molecular expression on CD34+ cells of integrins VLA-4 (alpha 4/beta 1), VLA-5 (alpha 5/beta 1), and LFA-1 (alpha L/beta 2) by interindividual (between mobilized PB and normal BM) and intraindividual (between mobilized PB and steady-state BM and PB in the same patient) analysis. The proportion of adherent clonogenic progenitor cells was significantly lower in PB than in BM, not only for total progenitor cells but also for mature and immature progenitor cells, and the difference was found for granulocytic and particularly for erythroid lineages. The lower adhesion capacity of PB CD34+ cells to stroma was associated with decreased expression (signal/noise MFI ratio) of integrin alpha 4, beta 1, alpha L, and beta 2 chains whereas that of alpha 5 chain did not differ from BM cells with the lowest expression level. Similar differences in integrin expression levels were also found between mobilized PB and steady-state BM CD34+ cells in the same patient except for the alpha L chain. Moreover, we demonstrated for the first time a strong positive correlation between mobilizing capacity and expression levels on mobilized CD34+ cells for the LFA-1 alpha L chain but not for VLA-4 or VLA-5. In conclusion, the decreased adhesion capacity of mobilized PB progenitor cells to stroma involves different maturation stages and different lineages. This is associated with down-regulation of integrins VLA-4 and LFA-1, but mobilizing capacity appears positively correlated with LFA-1 levels.

Antigens, CD34↗

PubMed2002

Peripheral blood stem cells differ from bone marrow stem cells in cell cycle status, repopulating potential, and sensitivity toward hyperthermic purging in mice mobilized with cyclophosphamide and granulocyte colony-stimulating factor.

Peripheral blood stem cells (PBSCs) are increasingly used in autologous stem cell transplantations. We investigated the mobilizing effect of a combined cyclophosphamide (CTX) and granulocyte colony-stimulating factor (G-CSF) treatment on progenitor cells (STRA) and primitive stem cells (LTRA) in normal and splenectomized CBA/H mice. This combined treatment not only resulted in mobilization but also in expansion of hematopoietic stem cell subsets. The latter phenomenon was somewhat suppressed in splenectomized animals, but in these mice an enhanced mobilization of STRA and LTRA cells into the peripheral blood was observed. Furthermore, we studied the engraftment potential of mobilized PBSCs. Mice transplanted with PBSCs engrafted significantly better compared to mice transplanted with bone marrow stem cells from control and mobilized mice. The repopulation curve was characterized by a less-deep nadir indicating that the differences occur during the initial phase after transplantation. Contamination of autologous PBSC transplants with malignant cells is noticed frequently and is the basis for urging the use of purging modalities. Here we used hyperthermia and found that the mobilized progenitor cells in peripheral blood are more resistant to hyperthermia than those in the bone marrow (i.e., a survival of 11 +/- 5% after 90 min at 43 degrees C for peripheral blood progenitors, compared to 0.5 +/- 0.4% in bone marrow of mobilized animals and 1.6 +/- 0.5% in normal animals, respectively). Hyperthermic purging does not eliminate the superior repopulating features of a PBSC graft, as is demonstrated by an increased median survival time of lethally irradiated mice transplanted with purged PBSCs. In conclusion, our data demonstrate that CTX + G-CSF-mobilized PBSCs have an enhanced engraftment potential concomitantly with a decreased cycling activity and hence a decreased hyperthermic sensitivity. These findings support the use of these mobilized PBSCs for autologous stem cell transplantation and strengthen the basis for using hyperthermia as a purging modality.

Animals↗

PubMed2006

The dynamic nature of mobility disability in older persons.

OBJECTIVES: To determine the rates of clinically meaningful transitions in mobility disability; evaluate how these transitions differ according to age, sex, and physical frailty; and depict the duration of the resulting episodes of mobility disability. DESIGN: Prospective cohort study. SETTING: General community in greater New Haven, Connecticut, from March 1998 to October 2004. PARTICIPANTS: Seven hundred fifty-four community-living older persons, aged 70 and older, who were nondisabled (i.e., required no personal assistance) in four activities of daily living. MEASUREMENTS: Mobility disability, defined as the inability to walk one quarter of a mile and to climb a flight of stairs, respectively without personal assistance, was assessed every month for up to 5 years. RESULTS: For both mobility tasks, rates per 1,000 person-months were higher for transitions from no disability to intermittent disability (34.7 for walking one quarter of a mile and 17.4 for climbing a flight of stairs), intermittent to continuous disability (52.0 and 42.5), continuous to intermittent disability (35.4 and 31.5), and intermittent to no disability (68.6 and 85.4) than for other transitions. Older age, female sex, and physical frailty were associated with greater likelihood of transition to states of greater disability and lower likelihood of regaining independent mobility. CONCLUSION: Mobility disability in older persons is a highly dynamic process, characterized by frequent transitions between states of independence and disability. Programs designed to enhance independent mobility should focus not only on the prevention of mobility disability but also on the restoration and maintenance of independent mobility in older persons who become disabled.

Activities of Daily Living↗

PubMed2005

The use of AMD3100 plus G-CSF for autologous hematopoietic progenitor cell mobilization is superior to G-CSF alone.

Hematopoietic progenitor cells (HPCs) traffic to and are retained in the marrow through the trophic effects of the chemokine stromal cell-derived factor-1alpha (SDF-1alpha) binding to its receptor, CXC chemokine receptor 4 (CXCR4). AMD3100 reversibly inhibits SDF-1alpha/CXCR4 binding, and AMD3100 administration mobilizes CD34(+) cells into the circulation. We therefore tested the hypotheses that the combination of AMD3100 plus granulocyte colony-stimulating factor (G-CSF) (hereafter A + G) would be superior to G-CSF alone (hereafter G) in mobilizing hematopoietic progenitor cells (HPCs) and that A + G-mobilized cells would engraft as well as G-mobilized cells. The primary objective was to determine whether patients mobilized more progenitor cells per unit of blood volume of apheresis after A + G administration versus G alone. Secondary objectives were to determine whether patients mobilized with A + G compared with G alone required fewer apheresis procedures to reach the target level at least 5 x 10(6) CD34(+) cells/kg for transplantation and to determine whether patients mobilized with A + G had at least a 90% success rate of autologous transplantation as assessed by neutrophil engraftment by day 21. Each patient served as his or her own control in a sequential mobilization design. All study objectives were met without significant toxicity. The results demonstrate that the combination of A + G is generally safe, effective, and superior to G alone for autologous HPC mobilization.

Adolescent↗

PubMed2000

Characterization and outcome of "hard to mobilize"' lymphoma patients undergoing autologous stem cell transplantation.

A "hard to mobilize" patient was defined as one in whom >or= 1x10(6) CD 34+ cells/kg cannot be obtained after two consecutive large volume aphereses. Forty-four consecutive Hodgkin's and non-Hodgkin's lymphoma patients who underwent autologous peripheral blood stem cell (PBSC) transplant treatment between June 1996 and June 1998 were included in this study. Twenty-one patients (48%) met the definition of "hard to mobilize" (Group I). All the rest of the patients (n=23) were the good mobilizers (Group II). The initial mobilization protocol for most patients was 10 microg/kg of G-CSF alone for both groups. For Group I, 7/21 (33%) patients were unable to achieve a minimal dose of >or= 1x10(6) CD34+ cells/kg even after a second mobilization attempt and/or bone marrow (BM) harvest (n=5). Overall, 11/21 (52%) required an additional mobilization and/or BM harvest. Only 3/21 (14%) patients were able to meet the target cell dose of >or= 2.5x10(6) CD34+ cells/kg (median of 4 apheresis). In contrast, 87% of Group II achieved the target dose with a median of 2 aphereses. Predictors of poor mobilization were greater than two prior treatment regimens (p=0.038) and the WBC count (<25,000/microL) on the first day of apheresis (p=0.053). Nineteen patients in Group I and all Group II completed treatment with a median time to engraftment of ANC>500/microl of 12 and 11 days, and platelet >20x10(3)/microl of 31 and 13 days, respectively. Outcome analysis revealed that 6/19 patients in Group I died of relapse within one year from transplant compared with only 2/23 of Group II who died of relapse (p=0.005, log rank test). There were no treatment related deaths in either group. Independent predictive features for "hard to mobilize" patients are a lack of significant increase in WBC count on the first day of apheresis and the number of prior treatment regimens. Poor mobilization appears to predict a worse outcome after autografting for lymphoma patients.

Actuarial Analysis↗

PubMed2000

Expression of the G-CSF receptor on hematopoietic progenitor cells is not required for their mobilization by G-CSF.

The mechanisms that regulate hematopoietic progenitor cell (HPC) mobilization from the bone marrow to blood have not yet been defined. HPC mobilization by granulocyte colony-stimulating factor (G-CSF), cyclophosphamide (CY), or interleukin-8 but not flt-3 ligand is markedly impaired in G-CSF receptor-deficient (G-CSFR-deficient) mice. G-CSFR is expressed on mature hematopoietic cells, HPCs, and stromal cells, which suggests that G-CSFR signals in one or more of these cell types was required for mobilization by these agents. To define the cell type(s) responsible for G-CSF-dependent mobilization, a series of chimeric mice were generated using bone marrow transplantation. Mobilization studies in these chimeras demonstrated that expression of the G-CSFR on transplantable hematopoietic cells but not stromal cells is required for CY- or G-CSF-induced mobilization. Moreover, in irradiated mice reconstituted with both wild type and G-CSFR-deficient bone marrow cells, treatment with CY or G-CSF resulted in the equal mobilization of both types of HPCs. This result held true for a broad spectrum of HPCs including colony-forming cells, CD34(+) lineage(-) and Sca(+) lineage(-) cells, and long-term culture initiating cells. Collectively, these data provide the first definitive evidence that expression of the G-CSFR on HPCs is not required for their mobilization by G-CSF and suggest a model in which G-CSFR-dependent signals act in trans to mobilize HPCs from the bone marrow.

Animals↗

PubMed2002

A review of the clinical management of mobile teeth.

The clinical management of mobile teeth can be a perplexing problem, especially if the underlying causes for that mobility have not been properly diagnosed. In some cases, mobile teeth are retained because patients decline multidisciplinary treatment that might otherwise include strategic extractions. This article discusses the relationship between occlusion and tooth mobility with an emphasis on identifying differences between increased mobility and increasing mobility. The indications, contraindications, and basic principles of tooth splinting are also reviewed. Provisional and definitive splints are defined and described with their respective occlusal considerations. Some mobile teeth can be treated through occlusal equilibration alone (primary occlusal trauma). Whereas mobile teeth with a compromised periodontium can be stabilized with the aid of provisional and/or definitive splinting (secondary occlusal trauma). It is important to consider splint therapy, because it may not only improve the prognosis of teeth, but may actually enhance the stability of the final prosthodontic treatment. The ultimate goal of successful management of mobile teeth is to restore function and comfort by establishing a stable occlusion that promotes tooth retention and the maintenance of periodontal health.

Dental Occlusion, Traumatic↗

PubMed1990

Anomalously slow electrophoretic mobilities of DNA restriction fragments in polyacrylamide gels are not eliminated by increasing the gel pore size.

The effect of gel pore size on the anomalous mobility of certain curved DNA restriction fragments in polyacrylamide gels was studied by comparing the electrophoretic mobilities of normal and anomalous fragments in gels of varying composition but constant acrylamide concentration. Molecular weight ladders were prepared from two 147 base pair G-C rich restriction fragments, called 12A (anomalous) and 12B (normal), obtained from the MspI digestion of plasmid pBR322. The electrophoretic mobilities of multimers of the two fragments increasingly diverged with increasing molecular weight. The anomalous mobility of fragment 12A was essentially independent of gel pore size, regardless of whether the pore size was varied by increasing the acrylamide concentration at constant cross-linker concentration or by increasing the cross-linker concentration at constant acrylamide concentration. The anomalous mobility of higher multimers of fragment 12A decreased with increasing gel pore size when the pore size was varied by changing the gel concentration. However, when the gel pore size was changed by varying the cross-linker concentration at constant acrylamide concentration, the anomalous mobility of higher multimers of fragment 12A went through a maximum and then decreased as the pore size was increased. Copolymerizing acrylamide with high molecular weight linear polyacrylamides had no effect on the anomalous mobility of the 12A multimer ladder, even though the apparent absolute mobilities of all fragments increased markedly. Only by incorporating charged residues into the gel matrix or by copolymerizing acrylamide with the intercalator ethidium bromide could the difference in mobility between the 12A and 12B multimer ladders be substantially reduced or eliminated. Similar results were observed with a molecular weight ladder containing 78 base pair repeats of the bending locus of kinetoplast DNA. These results suggest that pore size alone is not responsible for the anomalously slow migration of curved DNA molecules in polyacrylamide gels.

Base Sequence↗

PubMed2005

Investigation of the effect of ionic strength of Tris-acetate background electrolyte on electrophoretic mobilities of mono-, di-, and trivalent organic anions by capillary electrophoresis.

The effect of ionic strength of the background electrolyte (BGE) composed of tris(hydroxymethyl)aminomethane (Tris) and acetic acid on the electrophoretic mobility of mono-, di- and trivalent anions of aliphatic and aromatic carboxylic and sulfonic acids was investigated by capillary zone electrophoresis (CZE). Actual ionic mobilities of the above anions were determined from their CZE separations in Tris-acetate BGEs of pH 8.1 to 8.2 in the 3 to 100 mM ionic strength interval at constant temperature (25 degrees C). It was found that the ionic strength dependence of experimentally determined actual ionic mobilities does not follow the course supposed by the classical Onsager theory. A steeper decrease of actual ionic mobilities with the increasing ionic strength of BGE and a higher estimated limiting mobility of the anions than that found in the literature could be attributed to the specific behavior of the Tris-acetate BGEs. Presumably, not only a single type of interaction of anionic analytes with BGE constituents but rather the combination of effects, such as ion association or complexation equilibria, seems to be responsible for the observed deviation of the concentration dependence of the actual ionic mobilities from the Onsager theory. Additionally, several methods for the determination of limiting ionic mobilities from CZE measured actual ionic mobilities were evaluated. It turned out that the determined limiting ionic mobilities significantly depend on the calculation procedure used.

Acetic Acid↗

PubMed2004

Reducing mobilization of simian immunodeficiency virus based vectors by primer complementation.

BACKGROUND: Human gene therapy vectors based on primate lentiviruses harbour in contrast to oncoretroviruses the risk of vector mobilization by human immunodeficiency viruses (HIV). Infection of cells transduced with a lentiviral vector by HIV could lead to packaging of the lentiviral vector RNA into HIV particles and transfer of the vector. METHODS: A new approach based on primer complementation was developed to reduce the risk of vector mobilization. The primer binding site (PBS) of an SIV-based vector was mutated abolishing tRNA primer binding and thus blocking reverse transcription. This block was efficiently by-passed during vector production by providing an artificial tRNA matching the mutated PBS with titers reaching 10(6) infectious units/ml. RESULTS: Primer-complemented SIV vectors were mobilized from transduced cells by HIV-1 >150-fold less efficiently than vectors with wild-type PBS. Mobilization of the primer-complemented SIV vector by SIV was inhibited to a lesser extent indicating reduced efficacy of the primer complementation approach for preventing mobilization of lentiviral vectors by homologous virus. The analysis of the PBS of the vector DNA in target cells transduced with vectors containing mutated PBS in the absence of a matched tRNA suggests that formation of heterozygous particles followed by priming on the helper RNA and strand switch during reverse transcription can lead to mobilization of the primer-complemented vector by SIV, but not HIV-1. Although self-inactivating vectors were more efficient in preventing vector mobilization by HIV-1 than primer-complemented vectors, mobilization remained undectable only if both approaches were combined. CONCLUSIONS: The primer complementation approach should further reduce the risk of mobilization of self-inactivating SIV-based vectors by HIV-1 and thus increase their safety.

Animals↗

PubMed1995

Water mobility in poly(ethylene glycol)-, poly(vinylpyrrolidone)-, and gelatin-water systems, as indicated by dielectric relaxation time, spin-lattice relaxation time, and water activity.

The mobility of water molecules present in poly(ethylene glycol) (PEG)-, poly(vinylpyrrolidone) (PVP)-, and gelatin-water systems was determined by dielectric relaxation and 17O NMR spectroscopy. Water activity was also measured. Dielectric relaxation spectra indicate that all the polymer systems studied contained water exhibiting a dispersion at a frequency > 10(9) Hz; in other words, water with high mobility close to that of bulk water. The dielectric relaxation time of the highly mobile water increased as polymer concentration increased. The PVP- and gelatin-water systems also contained water exhibiting a dispersion at a frequency < 10(9) Hz, which can be considered to be "bound water" with a restricted mobility because of its association with polymer molecules. Dielectric relaxation spectroscopy was used to determine water mobility separately for the populations of highly mobile water and bound water, whereas NMR relaxation spectroscopy was used to determine the average mobility of both populations. The spin-lattice relaxation time of water in these polymer-water systems showed a deviation from the isotropic two-state model. Dielectric relaxation data indicate that this deviation can be ascribed to variations in the relaxation time of highly mobile water caused by a change in polymer concentration. The dielectric relaxation time of highly mobile water in the gelatin system did not change with a change in polymer concentration to the extent that it did in the PEG and PVP systems. This result is consistent with a slight change in water activity of the gelatin system with increasing polymer concentration.(ABSTRACT TRUNCATED AT 250 WORDS)

Chemical Phenomena↗

PubMed2000

Self-reported and performance-based mobility related to instrumental activities of daily living in women aged 62 years and older. A population study.

This study investigated the association between self-reported and performance-based mobility and instrumental activities of daily living (IADL) in 854 women aged 62 years and older from population-based studies in Göteborg, Sweden. Self-reported mobility was assessed by asking the subjects if they experienced difficulties when walking outdoors, walking indoors and mounting stairs. Performance-based mobility was evaluated by a Postural-Locomotion-Manual (PLM) test, which objectively and precisely measured the subjects' mobility of lower and upper limbs and movement co-ordination using an optoelectronic technique. Independence/dependence in IADL was evaluated according to 4 activities, namely cleaning, shopping, transportation and cooking. IADL dependence associated with both self-reported difficulties in mobility and poor performance in the PLM test. A logistic regression analysis showed that self-reported mobility and the locomotion phase in the PLM test were two independent explanatory factors of IADL dependence. This study indicates that self-reported mobility and the PLM test can be used to evaluate the mobility components of daily life activities. The combination of these two methods improves the assessment of an individual's mobility, and defines a risk group of functional decline. Given the limitations of a cross-sectional design, further longitudinal studies are needed.

Activities of Daily Living↗

PubMed1996

Granulocyte colony-stimulating factor-induced mobilization of peripheral blood stem cells for autologous and allogeneic transplantation. Fukuoka Bone Marrow Transplantation Group.

Peripheral blood stem and progenitor cells (PBSC and PBPC), which circulate at very low levels during steady-state hematopoiesis, show a transient but marked increase during hematologic recovery from marrow-suppressive chemotherapy. To ensure rapid and sustained hematologic engraftment after autologous PBSC transplantation, sufficient PBSC or PBPC must be infused. To confirm the utility of granulocyte colony-stimulating factor (G-CSF) in chemotherapy-induced PBSC mobilization, we investigated the effect of G-CSF on PBSC mobilization in leukemia and lymphoma patients. The study design was such that PBSC mobilization with and without G-CSF was assessed in the same patients. The results indicate that PBSC mobilization can be enhanced significantly when G-CSF is given during the recovery phase postchemotherapy. Interestingly, progenitor cells of different lineages could be mobilized by G-CSF. We subsequently investigated the effect of increasing G-CSF dose on PBSC mobilization during steady-state hematopoiesis in healthy adult donors. The results indicate that not only committed but also primitive progenitor cells are mobilized into the circulation in a dose-and time-dependent manner when G-CSF at 5, 10, or 15 micrograms/kg was given on each of 5 days and leukapheresis was performed on day 6. From our data we estimate that sufficient PBSC for engraftment after allogeneic PBSC transplantation can be collected on day 5 of administration of G-CSF at 10 micrograms/kg and by 10-1 leukapheresis on days 5 and 6. Furthermore, we found that some G-CSF-mobilized PBSC retained their self-renewal capability. These observations suggest that hematopoietic stem cells for allogeneic PBSC transplantation can be mobilized by short-term administration of relatively high-dose G-CSF.

Animals↗

PubMed2004

A mobile phone integrated health care delivery system of medical images.

With the growing computing capability of mobile phones, a handy mobile controller is developed for accessing the picture archiving and communication system (PACS) to enhance image management for clinicians with nearly no restriction in time and location using various wireless communication modes. The PACS is an integrated system for the distribution and archival of medical images that are acquired by different imaging modalities such as CT (computed tomography) scanners, CR (computed radiography) units, DR (digital radiography) units, US (ultrasonography) scanners, and MR (magnetic resonance) scanners. The mobile controller allows image management of the PACS including display, worklisting, query and retrieval of medical images in DICOM format. In this mobile system, a server program is developed in a PACS Web server which serves as an interface for client programs in the mobile phone and the enterprise PACS for image distribution in hospitals. The application processing is performed on the server side to reduce computational loading in the mobile device. The communication method of mobile phones can be adapted to multiple wireless environments in Hong Kong. This allows greater feasibility to accommodate the rapidly changing communication technology. No complicated computer hardware or software is necessary. Using a mobile phone embedded with the mobile controller client program, this system would serve as a tool for heath care and medical professionals to improve the efficiency of the health care services by speedy delivery of image information. This is particularly important in case of urgent consultation, and it allows health care workers better use of the time for patient care.

Cell Phone↗

PubMed1985

Glucocorticoid effects on membrane lipid mobility during differentiation of murine B lymphocytes.

The lateral motion of membrane lipids on lipopolysaccharide-stimulated murine B lymphocytes was measured using photobleaching recovery techniques. The mobility of the phospholipid analog 3,3'-dioctadecylindocarbocyanine iodide (DiI) was measured at 37 degrees C on B lymphocytes 48 h after stimulation by various concentrations of lipopolysaccharide. DiI mobility on lymphoblasts from cultures stimulated with 10 micrograms/ml lipopolysaccharide was reduced 50% compared with unstimulated, small B cells. However, both lower and higher lipopolysaccharide concentrations caused some decrease in lipid mobility. Lipid mobility was measured on B cells stimulated with 10 micrograms/ml lipopolysaccharide at zero time, on lymphoblasts at 18, 24, 48 and 72 h, and on immunoglobulin (Ig) -secreting lymphocytes at 96 h. The diffusion coefficient of DiI on both control and lipopolysaccharide-treated cells at zero time is 6.3 X 10(-9) cm2 X s-1. This value remains unchanged for unstimulated cells over 72 h. Lipid mobility of lipopolysaccharide-activated lymphoblasts decreased during incubation with lipopolysaccharide to 5.0, 3.4, 2.8 and 2.4 X 10(-9) cm2 X s-1 after 18, 24, 48 and 72 h, respectively. DiI mobility on immunoglobulin (Ig) -secreting lymphocytes identified at the foci of Protein A-coated sheep red blood cells plaques is 8.6 X 10(-9) cm2 X s-1, a value similar to that of unstimulated B cells. The effect of introducing various concentrations of a synthetic glucocorticoid, triamcinolone acetonide (TA), to 48 h lipopolysaccharide-stimulated cells for 6 h was examined. Maximal TA effect was observed at a concentration of 10(-7) M, which caused an increase in lipid mobility to 7.5 X 10(-9) cm2 X s-1. Exposing resting B cells (t = 0) or lymphoblasts (t = 24, 48 or 72 h) to TA for 3 h had no effect on lipid mobility. Treatment for 6 h with 10(-7) MTA increased DiI diffusion to 12.6, 9.9, 7.5 and 6.8 X 10(-9) cm2 X s-1 on control cells and on 24, 48 and 72 h lipopolysaccharide-activated lymphoblasts, respectively. A longer incubation of 12 h with 10(-7) MTA caused no further change in lipid lateral diffusion. The response was glucocorticoid-specific. In lymphoblasts (48 h) incubated an additional 6 h with 10(-7) MTA and a 100-fold excess of cortexolone or progesterone, the increase in lipid mobility was substantively blocked; estradiol and testosterone had no effect on lipid lateral diffusion.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1996

Chromatographic behaviour in reversed-phase high-performance liquid chromatography with micellar and submicellar mobile phases: effects of the organic modifier.

Continuing our earlier study of the retention behaviour in reversed-phase systems with aqueous mobile phases containing surfactants in concentrations lower (submicellar systems) and higher (micellar systems) than the critical micellar concentration (CMC), we investigated the chromatographic behaviour of various non-ionic solutes in mixed aqueous-organic micellar and submicellar mobile phases and their dependence on the methanol concentration. CMC values were measured for two cationic surfactant and one anionic surfactant in mixed aqueous-methanolic solvents, and were found to increase slightly with increasing methanol concentration. Depending on the character of the surfactant, a limiting concentration of methanol was found, above which micelles do not occur anymore. Sorption isotherms of the surfactants on an octylsilica gel column were measured as a function of the concentration of methanol in aqueous-methanolic solvents. A modified Langmuir equation was used to describe the distribution of the surfactants between the stationary and the mobile phases in the concentration range below CMC. The retention of several polar solutes was measured on an octylsilica gel column both in micellar and submicellar mobile phases containing methanol. The dependencies of the capacity factors of the solutes studied on the concentration of methanol in the mobile phase can be suitably described by the same form of equation as that conventionally used for aqueous-organic mobile phases that do not contain surfactants, but the slopes of the dependencies for a given solute are different in the two ranges of surfactant concentrations. The ratio of the two slopes is controlled by the interaction with micelles and is approximately equal to, below or above 1, depending on whether the solutes do or do not associate with the micelles, or are repulsed from them. Simultaneous control of the concentrations of the organic solvent and of the surfactant in the mobile phase can be used for fine tuning the selectivity of separation as a complement to commonly used adjusting concentrations of two organic solvents in ternary aqueous-organic mobile phases. These effects are illustrated by practical examples of submicellar HPLC with mobile phases containing methanol.

Adsorption↗

PubMed2005

Suppression of electroosmotic flow and its application to determination of electrophoretic mobilities in a poly(vinylpyrrolidone)-coated capillary.

A hydrophilic polymer, poly(vinylpyrrolidone) (PVP), was employed for suppressing the electroosmotic flow (EOF). A capillary was filled with aqueous PVP solution for coating the capillary wall with PVP; the PVP solution was then replaced by a migration buffer solution containing no PVP. Three types of PVP with different molecular weights were examined. The EOF was suppressed more effectively as the molecular weight of PVP increased. The EOF in the coated capillary was approximately 10-fold smaller than that of a bare capillary and was constant in the pH range of 6-8. The suppressed EOF was stable even when no PVP was added to the migration buffer. However, the EOF increased significantly when sodium dodecyl sulfate was added into the migration buffer. The method was applied for determining the electrophoretic mobilities of inorganic anions that have negative electrophoretic mobilities larger than the electroosmotic mobility of the bare capillary. A novel method for determining the electrophoretic mobilities was proposed based on the linear relationship between electric current and electrophoretic mobility. The electrophoretic mobility was proportional to the electric current. Therefore, the intercept of the regression equation represents the electrophoretic mobility at room temperature. The electrophoretic mobilities were in good agreement with the absolute electrophoretic mobilities.

Electrophoresis, Capillary↗