Magnetic resonance of a dextran-coated magnetic fluid intravenously administered in mice

Magnetic resonance was used to investigate the kinetic disposition of magnetite nanoparticles (9.4 nm core diameter) from the blood circulation after intravenous injection of magnetite-based dextran-coated magnetic fluid in female Swiss mice. In the first 60 min the time-decay of the nanoparticle concentration in the blood circulation follows the one-exponential (one-compartment) model with a half-life of (6.9 +/- 0.7) min. The X-band spectra show a broad single line at g approximately 2, typical of nanomagnetic particles suspended in a nonmagnetic matrix. The resonance field shifts toward higher values as the particle concentration reduces, following two distinct regimes. At the higher concentration regime (above 10(14) cm(-3)) the particle-particle interaction responds for the nonlinear behavior, while at the lower concentration regime (below 10(14) cm(-3)) the particle-particle interaction is ruled out and the system recovers the linearity due to the demagnetizing field effect alone.

Blood compatibility of particulate carriers investigated by cell electrophoresis and particle electrophoresis: a preliminary report

Polyethylene glycol (PEG) and dextran were covalently coupled, or only adsorbed, to the surface of three kinds of inorganic particles in order to shield their surface and reduce their nonspecific binding to red blood cells. Surface modification as well as interaction of particles with red blood cells was followed up by particle electrophoresis. This allowed a quick evaluation of the efficiency of polymer coupling. Moreover, the nonspecific binding of particles to red blood cells was easily investigated with cell electrophoresis, showing the inhibitory effect of immobilized PEG-5000 or dextran. The electrophoretic mobility analysis presented here may be used for screening blood compatibility of particulate drug carriers and could be helpful in formulating long-living circulating particles.

Covalent binding of polyethylene glycol to the surface of red blood cells as detected and followed up by cell electrophoresis and rheological methods

Cyanuric chloride activated polyethylene glycol (PEG)-5000 was covalently coupled to murine and human red blood cells (pegylated RBC). Our purpose was to camouflage RBC receptors, which is necessary for parasite invasion, a process essential to sustain parasitemia. Cell electrophoretic mobility analysis (CEM) of pegylated RBC distinguished a new population of cells bearing characteristic CEM. Pegylation of RBC also modified their rheological properties, which were documented by evaluation of cell deformability (based on cell transit time through calibrated micropores) and cell aggregation (as measured by ultrasonic interferometry). Homologous transfusion of pegylated RBC into murine malaria-infected mice had no significant effect on the cerebral malaria death rate in Plasmodium berghei-infected mice, but it reduced the peripheral blood parasitemia by a factor 2 while in Plasmodium yoelii infected mice, the parasitemia was dramatically reduced by a factor of 4. These experiments demonstrate that transfusion of pegylated RBC may inhibit peripheral parasitemia. Cell electrophoresis appears to be a useful tool to allow in vivo detection and to investigate the fate of transfused pegylated RBC.

Particle electrophoresis of micrometric-sized superparamagnetic particles designed for magnetic purification of cells

Measuring the electrophoretic mobility of superparamagnetic particles (0.5-4.5 microns mean size) was undertaken to probe the coupling of lectins and antibodies to their surface. Coupling was either noncovalent (antigen-antibody and biotin-streptavidin linkage) or covalent (tosyl-activated beads). The direct observation of the electrophoresis of single particles illuminated in dark field and processed by image analysis allowed the determination of their apparent electrophoretic mobility. Mobilities ranged from -0.5 micron s-1/CmV-1 to +1 micron s-1/CmV-1 when measured at 20 degrees C in 0.15 M NaCl and 30 mg/mL sorbitol, pH 7.4. The relative standard deviation was less than 0.1%. Surface immobilization of charged proteins onto the superparamagnetic beads shifted their electrophoretic mobility up to 200%; this was also quantitatively correlated with some specific properties (enzymatic activity, antigen-binding activity, lectin-binding activity). Although particle electrophoresis has mainly been reported for the study of surface adsorption phenomenon, it may be a versatile tool for controlling covalent modifications of particles designed for therapeutical targeting or chromatographic use and may also apply to a quantitative analysis of ligand-binding interactions.

Cell electrophoretic mobility and glycerol lysis of human erythrocytes in various diseases

Using an automated cell electrophoresis system equipped with an image processor, we studied electrophoretic mobilities of erythrocytes of healthy donors and of patients suffering from systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), hypergammaglobulinemia and diabetes mellitus (DM). On average, erythrocytes from SLE patients showed mean electrophoretic mobilities (EPM) which were significantly lower (p < 0.005) than the EPM of red blood cells of normal donors. Evaluation of mean EPM and standard deviations revealed that three groups of SLE patients could be distinguished regarding the electrophoretic behavior of their erythrocytes. Some patients had red blood cells with normal EPM, others had erythrocytes with significantly reduced EPM, and a third group appeared to have both kinds of erythrocytes. In addition, erythrocytes of various SLE patients showed enhanced resistance to lysis by glycerol and their membranes contained less quantities of band 3 proteins.

Characterization of a subpopulation of mouse red blood cells as preferential target for malarial invasion

Cell electrophoresis was used to study a distinct subpopulation of murine red blood cells (RBC). These RBC are normally found in the spleen and bone marrow. They appear in the peripheral blood when mice are mildly bled or sucked by mosquitos. These cells have been characterized as having larger size, light density, lower electrophoretic mobility, and being more resistant to lysis with unsaturated fatty acids and in glycerol-containing medium than mature erythrocytes. All their features suggest that their differentiation status represents an intermediate stage between reticulocytes and adult RBC. In vitro Plasmodium invasion tests showed their increased sensitivity to invasion by the parasites. The extent of their spreading in the blood was found to be strain-dependent, being more pronounced in C57B1/6 mice, highly susceptible to developing cerebral malaria after infection with Plasmodium berghei, as compared to Balb/c, a nonsusceptible strain of mice.

Surface modification of superparamagnetic nanoparticles (Ferrofluid) studied with particle electrophoresis: application to the specific targeting of cells

Colloidal aqueous suspension of superparamagnetic nanoparticles (9 nm in diameter) composed of maghemite (gamma Fe2O3) and forming an ionic ferrofluid in aqueous solution are covalently coupled with lectins, enzymes or antibodies, using specific thiol chemistry. The surface charge modifications of nanoparticles, caused by ligand coupling, were monitored by measuring their electrophoretic mobilities using laser-Doppler velocimetry. Particle electrophoretic mobility (PEM) changes are shown to correlate well with the amount of ligand fixed on the particles, as probed by its biological activity. The PEM method provides a useful tool to optimize ligand immobilization at the surface of nanoparticles, and may be advantageous when biological activity measurements are not convenient.

Membrane modifications of red blood cells in Alzheimer's disease

Red blood cells (RBC) from 24 Alzheimer's disease (AD) patients, 18 age- and sex-matched nondemented (ND) patients, hospitalized in the same facility for orthopedic problems, and 18 healthy volunteers aged 30-52 years were studied in order to gain insight into the nature of RBC membrane modifications in AD. Significant differences were found between RBC from AD and ND patients or young controls respectively for annexin V-binding (45.5 +/- 18.0% vs 27.1 +/- 14.7 and 2.7 +/- 1.9, p = .003), fraction of glycerol resistant cells (30.8 +/- 11.1% vs 19.6 +/- 6.4 and 10.2 +/- 3.1, p = .026), cell electrophoretic mobility in polymer (1.028 +/- 0.022 microns sec-1 V-1 cm vs 1.046 +/- 0.022 and 1.053 +/- 0.021, p = .02) and only limited significance for the filterability (1.46 +/- 0.12 msec vs 1.58 +/- 0.11 and 1.54 +/- 0.11, p = 0.1). A logistic analysis, using simultaneously several features as independent variables, suggested the combined use of annexinV- binding, glycerol resistance, and cell filterability which allowed the assignment of 95% of patients from this cohort to the right group. A prospective analysis of a larger cohort is required for the estimation of the diagnostic value of this test battery. In addition, the high level of annexin binding is characteristic of a disruption of the phospholipid asymmetry in aged or damaged cells, while the high glycerol resistance combined with low electrophoretic mobility an rigidity characterize young RBC, thus indicating an enhanced turnover of RBC in Alzheimer's disease.

Effect of fatty acid treatment in cerebral malaria-susceptible and nonsusceptible strains of mice

Cerebral malaria-susceptible (C57BL/6) mice infected with Plasmodium berghei ANKA (PbA) developed low parasitemia and died from typical neurological symptoms between 8 to 10 days after infection. In contrast, nonsusceptible (BALB/c) mice developed high peripheral blood parasitemia and died 22-24 days later without neurological implications. Daily injections of fatty acids (FA) during the first 3 days after infection protected C57BL/6 mice from cerebral symptoms but had no effect on BALB/c mice. Thus, treated C57BL/6 mice developed hyperparasitemia and died 25 days after infection, like BALB/c mice. Red blood cells from C57BL/6 control mice were found to be more resistant to lysis by linoleic acid than those of BALB/c mice. Three days following infection with PbA, these differences disappeared. Treatment with FA prevented these changes. We concluded that the host's cells were altered soon after infection and that the nature and degree of alterations depended on the mouse strain, thus determining the eventual outcome of the infection. Likewise, the effects of FA might not be directed against the parasite but rather seem to act early after infection on these parasite-induced modifications of host cells.

Use of annexin V-ferrofluid to enumerate erythrocytes damaged in various pathologies or during storage in vitro

Recombinant human annexin V was bound covalently to 9 nm maghemite (gamma Fe2O3) nanoparticles, yielding annexin-ferrofluid (AnxFF), and used to separate annexin-bound red blood cells (RBC) in a magnetic field and estimate their percentage in various bloods. Annexin binding in normal human RBC increased proportionately with storage from 8% on day 2 to 42% on day 100. Enhanced AnxFF binding was associated with various pathologies. Thus, normal blood contained 10.7 +/- 5.9% AnxFF binding RBC; bloods with normal sedimentation rates (albeit with some disease necessitating analysis) contained 23.5 +/- 6.2%; those with high sedimentation rates contained 51.5 +/- 12.3%; sickle cell anaemia patients' blood contained 50.0 +/- 9.3%, and bloods from patients with other pathologies (deforming rheumatic disease, cancer necessitating chemotherapy, etc.) contained 58.6 +/- 7.6% AnxFF binding RBC. Enhanced Ca+2-dependent annexin binding reflects a loss of the asymmetric distribution of anionic phospholipids in plasma membranes which may constitute a signal for the destruction of the modified cells by the reticuloendothelial system. Once these preliminary results are confirmed, the determination of the fraction of AnxFF bound erythrocytes, following their magnetic separation, could prove a simple and rapid quality test for example in the context of blood transfusion.

Alterations of uninfected red blood cells in malaria

Red blood cell (RBC) negative charges and resistance to linoleic acid (LNA)-induced lysis were studied in Plasmodium yoelii-infected mice and in malaria (P. falciparum)-affected individuals. RBCs from mice infected with P. yoelii showed a progressive decrease in the net surface negative charges at 24 h after infection, reaching a minimal value on day 3, followed by a second phase that was characterised by a recovery to normal levels on day 6. Resistance to linoleic acid follows similar kinetics. These alterations preceded the appearance of parasites in the peripheral blood. A similar increase in LNA-induced lysis was observed in RBCs from malaria-affected individuals. These early membrane alterations of uninfected RBCs could be responsible for spreading of infection and RBC lysis during infection.

Cyclophosphamide-induced suppressor cells in nude mice

Lymphocytes regenerated after treatment with a high dose of cyclophosphamide (CY) were characterized in nude mice. Ten days after a single injection of 200 mg/kg CY into nude mice, regenerated spleen cells suppressed in vitro primary and second antibody production against sheep red blood cells. The CY-treated spleen cells exhibited normal natural killer (NK) activity, very low B and T cell content, but increases in cell surface charge [electrophoretic mobility (EPM)] and histamine receptors. The suppressor cells could not be removed by treatment with anti-Thy-1 plus complement (C), or treatment with antiasialo GM1 (aGM1) plus C, which abrogated NK activity. It was concluded that CY-treated spleen cells, which exhibited high EPM and histamine receptors, comprise the natural suppressor cells which are Ig-, Thy-1- and aGM-1.

Clinical improvement in advanced cancer disease after treatment combining histamine and H2-antihistaminics (ranitidine or cimetidine)

In a randomized study 31 patients with advanced cancer disease in whom classical anticancer therapy had been abandoned received a daily combination of subcutaneous histamine and oral H2-antihistaminics. In 27 patients, treatment induced a marked clinical improvement as shown by a large rise in performance status (Karnofsky scale). Ten patients were still alive 3-14 months after initiation of treatment. Average survival in the 31 treated patients (172 +/- 113 days) was significantly longer than in 34 non-treated patients with similar advanced cancer (26 +/- 16 days, P less than 0.00001). In six treated patients, the size of liver and lung metastases decreased. Histamine was perfectly tolerated up to 4 mg/day.

Effect of a protein bound polysaccharide (PS-K) on tumor development and infections in splenectomized rats and mice

Daily oral administration of PS-K, an immunomodulating agent, was found to improve survival rate in tumor bearing mice and rats and to decrease susceptibility to infection in mice. Surprisingly, splenectomized tumor bearing rats and mice responded better to PS-K treatment as measured by survival rate, tumor size and immunosuppressive properties of serum. The mechanism of PS-K antitumor activity in both experimental systems might be due to the alteration of splenic immune suppressive mechanisms during tumor growth in the host. On the other hand, host resistance to acute infection was found to be less dependent upon the presence or absence of spleen suggesting a different mechanism of PS-K activity in acute infectious disease.

Spontaneous maze ambulation in two mouse strains

A simple device is described, which permits us to quantify several parameters of spontaneous behaviour of small animals. Using this device with mice we obtained statistically satisfactory results, showing a strong genetic influence on the behavioural characteristics tested.

Further studies on the H-2 linked dependence of the adjuvant action of Brucella abortus

The B 19S strain of Brucella abortus is found to act as an adjuvant to the anti-sheep red blood cell (SRBC) reaction in some congenic strains of mice but not in others. If the recipient is H-2b, there is no adjuvant effect (B 19S); neither is there (thymus-dependent anti-B 19S reaction as measured by thymocyte activation and change of electrophoretic mobility. In contrast, there is a thymus-independent anti-B 19S reaction (production of haemagglutinins) as good in the H-2b mice as in the others. Experiments with T cell deprived mice show that the adjuvant action of B 19S is thymus-dependent. As the anti-SRBC reaction without adjuvant is also thymus-dependent, it is difficult to distinguish anti-SRBC and anti-B 19S reactions from the adjuvant action of B 19S on the anti-SRBC reaction. Several explanations are possible, all involving H-2 (Ir?) controlled thymus dependent mechanisms.

Immunological characteristics of lymphoblasts and lymphocytes in acute lymphoblastic leukaemia in children

By analysing the electrophoretic mobility (EM) of lymphocytes and by comparing their surface charge it is possible to distinguish rapid-moving lymphocytes (T) and slow-moving lymphocytes (B). The authors studied the EM of blood lymphocytes in children suffering from acute lymphoblastic leukaemia, before they underwent treatment. At the same time they carried out a study of classical immunological markers (E rosettes, membrane immunoglobulins, and blastic-transformation ability). The authors were able to distinguish three types of lymphocytes according to their EM i.e., rapid, slow or intermediate. This heterogeneousness could be explained by the fact that the origin of leukaemic proliferation may vary according to different stages in the maturation of the lymphoid cells. It would seem premature to establish any correlation between the initial clinical signs of the disease and its evolution.

Influence of milk source on transplantability of histocompatible mammary tumours in mice

It is confirmed that C3H mammary tumours are much more easily transplantable in histocompatible recipients when these have been reared on C3H milk, than when they have been reared on milk from the inbred Swiss/B strain. By contrast, A.CA mammary tumours transplanted in histocompatible hosts reared on A.CA or Swiss/B milk, grow almost equally well in both sorts of recipient. Thus, rearing on Swiss/B milk has different effects on the transplantability of mammary tumours of C3H and A.CA. On the other hand, recipients which were reared on C3H or A.CA milks accept grafts of C3H mammary tumours about equally, suggesting that milks from A.CA and C3H have the same effect on the transplantability of C3H mammary tumours. The different action of Swiss/B milk on tumours of C3H and A.CA seems best attributed to differences between C3H and A.CA tumours or between mouse strain genotypes. By contrast, the transplantability of C3H mammary tumours is significantly changed when the recipients were reared on milk from the RIII strain instead of C3H. These facts suggest that the milk from RIII has an action which differs from that of both C3H and A.CA in this respect. The data are discussed on the basis of a differential tollerance-inducing action of mammary tumour viruses (MTVs) which infect C3H, A.CA and RIII, and have an important role in tumour induction.

Splenic modifications induced by cyclophosphamide in C3H/He, nude, and "B" mice

The spleen cell population of adult C3H/He mice injected with a single sublethal dose of cyclophosphamide (CY) has been analyzed. An initial phase of spleen atrophy is followed by a considerable hypertrophy, and a progressive return to normal. During the phase of spleen atrophy, both B and T cell compartments are depleted, as estimated by the percentages of cells killed by anti-Thy 1-2 and anti-Ig antisera plus complement. During the stage of regeneration, the percentage of Ig + cells increases rapidly, and at the peak of splenomegaly, the percentage of Ig + cells is high whereas almost no Thy 1-2 + cells are detectable. Progresively, the spleen cell content returns to the original values. In thymo-deprived mice (nude mice and B mice) the percentage of null cells increases during the stage of regeneration, and B mice develop a large number of Ig +-bearing cells. Histologic examination shows that follicles (B-dependent areas) disappear 1 to 2 days before periarteriolar sheaths (T-dependent areas). At the peak of splenomegaly the architecture of the spleen is destroyed, and the interstitial tissue is composed of a dense and uniform layer of lymphoid cells. Progressively, the architecture returns to normal. In nude mice, the disappearance of follicles, and the appearance of a homogenous layer of lymphocytes has been observed. When analyzed for their pattern of electrophoretic mobilities (E.M.), spleen cells from untreated mice reveal two peaks of E.M. 0.80 and 1.15 micron x s-1 x V-1 x cm-1. After CY treatment, during the step of splenic hypertrophy, these two peaks disappear, and a single peak of intermediate mobility appears. In T-deprived mice, a single peak of the same mobility is detected at this stage. The nature and origin of cells which appear during the phase of regeneration are unclear, but their appearance in T-deprived mice argues against thymo dependence. These spleen cells have the ability to suppress the response of normal spleen lymphocytes to T and B cell mitogens.

Electrophoretic mobility of lymphocytes in new born

T lymphocytes in normal new born at the 4th day after birth have an electrophoretic mobility of 1.04, quite slower than adult normal T lymphocytes (1.13), but the same of the EM of lymphoblasts of ALL (1.04).

The action of various sera on colony formation and DNA synthesis of murine thymocytes in culture

Murine thymus cells were caltivated up to 10 days in a semi-solid medium. Both macroscopically visible colonies and DNA synthesis (identified by 3H-thymidine incorporation) were counted with and without added sera. According to their origins the sera exerted different modifications of the cultivated cells behaviour. Changes of colony number and of thymidine incorporation were quite independent on each other.

Blood lymphocytes in acute lymphoid leukaemia in remission and in relapse. Predictive value of electrophoretic mobility and refringence

Blood lymphocytes were studied during the evolution of acute lymphocytic leukaemia, including remissions and relapses, under chemotherapy and immunotherapy. Lymphoblasts migrate as a uniform population and have a mean electrophoretic mobility of 1.04 mum-sec-1. V-1cm. These lymphoblasts are also refringent. The relapse seems to be preceded by a slowing of the electrophoretic mobility of fast cells and a rise in the percentage of refringent lymphocytes.

Immunological reactivity to sheep red blood cells in three congenic resistant strains of mice

(1) Immunological reactivity to sheep red blood cells was tested in three congenic resistant strains of mice and was found to vary according to the H-2 locus and its alleles. The reactivity of the strains in decreasing order is: A. CA, A/Sn, A. BY.

(2) Non-specific immunostimulation with Brucella increases the immune response to sheep red blood cells in the A. CA and A/Sn strains but not in strain A. BY. This immunostimulation with Brucella is H-2 dependent.

(3) Methylcholanthrene has an immunodepressive effect on the immunological reactivity to sheep red blood cell antigens in the three strains of mice, each strain being equally affected.