Search PubMed⌕ Search

Biomedical subjects

M Zborowski

Publications and source records attributed to M Zborowski.

54 records · Page 3Linked to original sources
PubMedDate not supplied

Evaluation of eluents from separations of CD34+ cells from human cord blood using a commercial, immunomagnetic cell separation system.

Human CD34+ cells from cord blood were separated in a two-step process using a commercial, immunomagnetic cell retention system. The performance of the system was evaluated by analyzing a number of eluents from the separations with a number of analytical techniques. In addition to cell counts and flow cytometry analysis, a new experimental technique that is undergoing development, cell tracking velocimetry (CTV), was used. CTV measures the degree to which a cell is immunomagnetically labeled, known as the magnetophoretic mobility, of a population of cells on a cell-by-cell basis and presents the results in the form of a histogram similar to flow cytometry data. The average recovery and purity of CD34+ cells from 10 separations was 52% and 60%, respectively. CTV analysis indicated that the mean magnetophoretic mobility of the positively enriched CD34 cells was 9.64 x 10(-5) mm3/T-A-s, while the mean mobility from negative eluents was -2.02 x 10(-6) mm3/T-A-s, very similar to the mobility of unlabeled cells. Within the positive eluents, the range of magnetophoretic mobility was approximately 50-fold, representing a plausible 50-fold range in surface CD34 antigen expression. CTV analysis also indicated that in some separations, positive cells were not retained by the immunomagnetic cell retention system. Finally, preliminary studies indicate that monocytes might be a primary cause in the lower purities and recoveries seen in this study. It is suggested that the monocytes phagocytose the magnetic nanobeads and become sufficiently magnetized to be retained within the Miltenyi column, reducing the purity of the positive eluent.

Antigens, CD34↗
PubMedDate not supplied

Separation of a breast cancer cell line from human blood using a quadrupole magnetic flow sorter.

We have developed a quadrupole magnetic flow sorter (QMS) to facilitate high-throughput binary cell separation. Optimized QMS operation requires the adjustment of three flow parameters based on the immunomagnetic characteristics of the target cell sample. To overcome the inefficiency of semiempirical operation/optimization of QMS flow parameters, a theoretical model of the QMS sorting process was developed. Application of this model requires measurement of the magnetophoretic mobility distribution of the cell sample by the cell tracking velocimetry (CTV) technique developed in our laboratory. In this work, the theoretical model was experimentally tested using breast carcinoma cells (HCC1954) overexpressing the HER-2/neu gene, and peripheral blood leukocytes (PBLs). The magnetophoretic mobility distribution of immunomagnetically labeled HCC1954 cells was measured using the CTV technique, and then theoretical predictions of sorting recoveries were calculated. Mean magnetophoretic mobilities of (1-3) x 10(-4) mm(3)/(T A s) were obtained depending on the labeling conditions. Labeled HCC1954 cells were mixed with unlabeled PBLs to form a "spiked" sample to be separated by the QMS. Fractional recoveries of cells for different flow parameters were examined and compared with theoretical predictions. Experimental results showed that the theoretical model accurately predicted fractional recoveries of HCC1954 cells. High-throughput (3.29 x 10(5) cells/s) separations with high recovery (0.89) of HCC1954 cells were achieved.

Algorithms↗
PubMedDate not supplied

Flow through, immunomagnetic cell separation.

A brief, process-oriented overview of immunologically based cell separation technology is presented. In addition, the design and preliminary experimental data of two unique flow-through immunomagnetic cell separation devices are presented. The first design is based on a dipole magnetic field, while the second design is basis on a quadrupole magnetic field. The dipole design can "fractionate" an inlet, magnetically labeled, cell stream into different outlet streams on the basis of the degree to which the cell is immunomagnetically labeled. The quadrupole separator splits an inlet, immunomagnetically labeled, cell stream into two outlet streams in which the purity, recovery, and potentially the degree to which the cells are immunomagnetically labeled is controlled by the flow rates in the inlet and outlet flows. A 99% purity and 86% recovery have been achieved with this system. Some distinct advantages of these two systems are the potential of high purity, recovery, and throughput at a cost which is potentially significantly lower than current, comparable technologies.

Electrochemistry↗
PubMedDate not supplied

Temperature dependent protein removal by large pore membrane filtration.

The high cost and clinically associated side-effects of plasma exchange treatment warrant development of on-line plasma fractionation techniques. Cryoglobulin removal from cryoglobulinemic plasma is particularly amenable to membrane filtration in the cold (cryofiltration). Temperature effects on filtration were studied in vitro using a large pore (nominal average size, 3 microns), low surface area (0.14 m2) filter. Plasmas with high concentrations of cryoprecipitable proteins (CPP; greater than 1.1 micrograms/ml) and immune complexes (IC; greater than 400 U/ml) were obtained from consenting cryoglobulinemic patients by plasma exchange. Removals of IC and CPP were highly temperature dependent, and high ratios of IC, CPP, and albumin removal were achieved (e.g., sieving coefficient [SC] = 0.05 and 0.91 for CPP, and SC = 0.94 and 0.95 for albumin at 4 degrees C and 23 degrees C, respectively). Clinically required volumes of plasma (greater than 2L) were processable. Cryofiltration with this new, high performance cryoglobulin filter is selective and may substantially reduce the clinical need for plasma replacement products.

Cryoglobulinemia↗
PubMedDate not supplied

Extracorporeal endotoxin removal in a canine model of septic shock.

The authors induced endotoxic shock in an animal model and attempted to treat this state by direct hemoperfusion over a modified anion sorbent column. It has been shown that the reversal of septic shock correlates with the efficiency of extracorporeal endotoxin removal. In this experiment, there were five control animals (sham) and five test animals (hemoperfusion over sorbent column). The efficacy of treatment was evaluated by survival at 24 hr, changes in mean arterial pressure, blood-acid base balance, and plasma endotoxin levels. There was 0% survival in the control group and 100% survival in the test group. The control dogs never recovered from shock or metabolic acidosis, but the test animals were at their initial values for these parameters by 6 hr. The endotoxin levels measured at 6 hr were higher in the control group (265 +/- 88 ng/ml) as compared with the test group (7.0 +/- 6.2 ng/ml). Direct hemoperfusion over a modified sorbent column effectively removed endotoxin and reversed the course of fatal septic shock.

Acid-Base Equilibrium↗
PubMedDate not supplied

Clinical trials of a cryoglobulin filter.

The authors report the results of clinical trials of a high capacity cryoglobulin filter (Cryofilter) in seven patients with cryoglobulinemia unresponsive to high doses of prednisone or immunosuppressive drugs who required plasmapheresis. The objective of this study was to test the safety and efficacy of the cryofilter in a limited patient population according to the investigational Device Exemption guidelines of the FDA. The cryoglobulins were selectively filtered from plasma at 4 degrees C by a cryofilter characterized by a membrane surface area of 0.135 m2 and an average pore size of 4.3 microns. Safety was evaluated by patients vital signs, complement activation, and clinical score of symptoms in the course of 10 treatments. Efficacy of cryofiltration was evaluated by comparing sieving of the cryoglobulins to that of albumin; immunoglobulins G, A, and M; and fibrinogen. All seven patients completed the series of 10 treatments without notable complement activation or any signs of discomfort. The cryofilter was particularly selective in patients with high cryoglobulin concentrations. Improvement in clinical symptoms was observed in all patients.

Adult↗
PubMedDate not supplied

Cryofiltration apheresis for treatment of cryoglobulinemia associated with hepatitis C.

Cryofiltration apheresis (CA) is a specific therapy for treatment of patients with cryoglobulinemia. We evaluated the safety and efficacy of CA in patients with mixed cryoglobulinemia associated with hepatitis C. As reported previously, the Cryoglobulin Filter comprises a membrane module inside a refrigeration unit on-line with a Spectra Apheresis System (COBE, Denver, CO). The efficacy of cryofiltration was measured by comparing the sieving coefficient of cryoprecipitable proteins (CPP) to that of albumin and comparing the systemic CPP concentration ratio post to pre treatment. Five patients were enrolled in this study, and a minimum of 10 procedures were performed for each patient. The risk for hepatitis C was multiple blood transfusions, intravenous drug abuse, immunosuppressive therapy, or renal transplantation. Four patients had Type II mixed cryoglobulinemia, and one patient had Type III. Four patients had chronic renal failure; one with liver cirrhosis received alpha interferon along with CA. One patient had no response to conventional plasma exchange and immunosuppressive therapy secondary to repeated infections and sepsis; CA was the only viable therapy for this patient. The maximum CPP concentration before therapy ranged from 1,440 to 7,440 micrograms/ml. The plasma CPP sieving coefficient at 1 L filtrate ranged from 0.25 to 0.74 (average +/- SE, 0.51 +/- 0.19; n = 39). The sieving coefficient for albumin was 1 (n = 50). The systemic CPP ratio post to pre treatment ranged from 0.28 to 0.83 (average +/- SE, 0.59 +/- 0.20; n = 37). No adverse effects specific to CA were observed. The CA was safe and effective and possibly the only choice of therapy in patients with cryoglobulinemic hepatitis C who have no response to plasma exchange and immunosuppressive therapy.

Adult↗
PubMedDate not supplied

Magnetic flow sorting using a model system of human lymphocytes and a colloidal magnetic label.

Cells of identical physical properties that differ in the expression of surface proteins can be sorted conveniently using immunospecific stains conjugated to fluorescent, or magnetic, labels. Immunomagnetic cell sorting using commercial batch sorters offers advantages of high sorting capacity, high viability of sorted fractions, and high depletion rates; its disadvantages are low enrichment rate and batch processing. The authors developed and tested a continuous, flow-through magnetic cell sorter for small volume, experimental cell enrichment. Freshly isolated human peripheral lymphocytes were labeled using an immunofluoromagnetic sandwich consisting of mouse anti human CD8 monoclonal antibody-fluorescein conjugate and rat anti mouse polyclonal antibody-colloidal iron-dextran conjugate. A total of 2-3 min lymphocytes were sorted per hour using a saturation magnetic field of 1.334 T and a five channel sorter. The fluorescent cells were distributed among the channels in relation to their fluorescence intensity and magnetic susceptibility. The purity (68-85%) and enrichment rates (16-34x) were comparable to those of commercial batch magnetic separators; sorting capacity and recovery of the enriched fractions (up to 32%) were limited by the small scale of the sorter. Future direction is focused on increasing the resolution, recovery, and sorting capacity of the enriched fractions, and testing the sorter on other cell systems.

Animals↗
PubMedDate not supplied

Rapid cell isolation by magnetic flow sorting for applications in tissue engineering.

Rapid and efficient cell sorting methods are important for tissue progenitor cell isolation. We built and evaluated a laboratory prototype of a continuous flow, quadrupole magnetic cell sorter. The sorter was tested on a model cell system of human peripheral lymphocytes. The helper T cell subpopulation was targeted by primary, mouse anti-CD4 monoclonal antibody conjugated to a fluorochrome (FITC), and magnetized by secondary, anti-FITC antibody magnetic colloid. The purities and recoveries of the cell fractions were measured by flow cytometry and an automated cell counter. Cells were spread across the flow according to their magnetophoretic mobilities. The purity of the CD4 cell enriched fraction was 99.6%, and the purity of the CD4 cell depleted fraction was 2% for an initial CD4 cell purity of 36%; the corresponding recovery of the enriched CD4 cell fraction was 59% at a sorting speed of 4,200 cells/s (four experiments). The recovery could be increased to 90% with a concomitant decrease in the purity of CD4 cell enriched fraction to 66%. This type of sorting should be applicable to any cells in suspension for which a suitable antibody exists, in particular, to large, fragile cells.

Antibodies, Monoclonal↗
PubMedDate not supplied

Do humoral factors removed by plasmapheresis suppress the cellular immune system in cryoglobulinemia?

The efficacy of plasmapheresis (PP) is believed to be primarily related to the removal of plasma humoral factors. Little is known, however, about the effect of solute removal on cellular systems. The effect of the presence of cryoprecipitable proteins (CPPT) on mononuclear blastogenesis (MNB) and polymorphonuclear cell phagocytosis (PMN-P) was studied. MNB stimulated by concanavalin A (Con A), phytohemagglutinin (PHA), and pokeweed mitogen (PWM) was significantly inhibited in cryoglobulinemic (CG) patients to 70, 75, and 60% that of normal controls, respectively. PMN-P were significantly suppressed to 30% that of normals. CPPT purified from cryoglobulinemic plasmas, type I and type III CG, exhibited higher suppressive effects (and in a concentration dependent manner) on normal MNB and PMN-P than albumin used as a control. The studies indicate that patients with CG have defective leukocyte function and that CPPT have suppressive effects on normal leukocyte function in vitro. Removal of plasma CPPT may improve the immunologic status of CG patients.

Cryoglobulinemia↗
PubMedDate not supplied

Membrane pore size and filtration selectivity in cryoglobulinemic plasma fractionation.

Efficiency of albumin (Alb) and immunoglobulin G (IgG) separation from cryoprecipitable proteins (CPP) and IgM was compared between a membrane plasma fractionator with a mean pore diameter (MPD) of 0.1 micron, surface area of 0.65 m2, and a new large pore diameter filter with a MPD of 4.3 microns, and surface area of 0.14 m2. In five in vitro tests at 4 degrees C using polyclonal cryoglobulinemic (CG) plasma from a patient treated by plasma exchange (PE), the large pore filter retained only 22% of the mass of Alb, and a comparable amount of CPP and IgM, as compared to the plasma fractionator, at a fraction of its total retention capacity. The new filter can replace PE in treatment of polyclonal CG.

Cryoglobulinemia↗
PubMedDate not supplied

Effect of a pulsing electromagnetic field on metabolically derived osteoporosis in rats: a pilot study.

The literature suggests that a pulsating electromagnetic field (PEMF) is effective against bone loss in disuse osteoporosis. This study was conducted to evaluate the effects of PEMF on metabolically derived osteoporosis in rats. Sixteen 5 month old female Sprague-Dawley rats were divided into three groups (G-1,2,3). G-1 was given a normal diet and no exposure to PEMF; G-2,3 were oophrectomized and fed a low calcium diet for 8 months; and G-3 was also exposed for 24 hr/day to PEMF generated by applying a 15 Hz, 5.6 A peak to peak square wave to Helmholtz coils (64 cm I.D., 200 turns/coil). The rats were sacrificed at 4, 6, and 8 months. Skeletal changes were analyzed by measurements of acid extracted bone calcium and bone mineral content (BMC) using single photon absorptiometry (SPA). Although all animals started at approximately the same weight (mean of 290.0 g), G-2 showed a more progressive increase. While the mean weight after 8 months in G-1 was 350.0 g, and 352.5 g for G-3, that in G-2 was 400.0 g. The calcium content of the femur in G-2 and G-3 at 8 months was lower than that of G-1, but there were no significant differences among the three groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

Pore size and temperature effects in membrane separation of albumin from immunoglobulins.

A series of ethylene-vinyl alcohol co-polymer hollow fiber membranes, differing in maximum pore diameter (0.01, 0.02, 0.03 micron), in modules of 2 m2 total surface area, were evaluated for separation of immunoglobulins G and M (IgG and IgM) from albumin (Alb) in normal human plasma at two different temperatures (4 degrees C and 37 degrees C). Separation was based on molecular size differences. In the dead end mode, with constant flow rate (20 ml/min) filtration, nearly total recovery of Alb, 27% rejection of IgG, and 87% rejection of IgM at VT = 2.4 L (total volume of filtrate accumulated at transmembrane pressure delta p = 300 mmHg) was observed for the largest pore membrane at 37 degrees C. A significant increase in IgG rejection to 50% was observed at 4 degrees C for this membrane, with a concomitant decrease of VT to 1 L. Average rejection coefficients of representative solutes, and delta p dependence on filtrate volume, were analyzed using the log-normal regression method and membrane pore blocking models. Filtration characteristics were noted to be dominated by the native membrane properties at 37 degrees C, and by solute-solute and solute-membrane interactions at 4 degrees C.

Cholesterol, HDL↗
PubMedDate not supplied

In vitro low frequency electromagnetic field effect on fast axonal transport.

The objective of this study was to evaluate the effects of a low frequency electromagnetic field on fast axonal transport for future neuroprosthetic applications. Changes in speeds and densities of retrograde fast organelle transport in rat sciatic nerve preparations were measured in vitro upon exposure to 15 and 50 Hz pulsed magnetic fields with peak intensities of 4.4 and 8.8 mT. Maximum current density of the induced eddy current was calculated to be about 40 microA/cm2. Video enhanced differential interference contrast microscopy was used to record axons supporting active organelle transport. Strong effects were observed in myelinated axons (cessation of transport in up to 10 min). Such effects may eventually be used as part of a neuroprosthesis to noninvasively modify or couple to various parts of the nervous system.

Animals↗
PubMedDate not supplied

Evaluation of a miniature blood glucose sensor.

A miniature version of the electrocatalytic glucose sensor has been designed and fabricated with thick-film metalization technology. The in vitro stability tests of the sensor were performed in buffered saline, human plasma ultrafiltrate, and bovine plasma. For bovine plasma studies the sensor was directly coated with a semipermeable ethylene vinyl alcohol (EVAL) membrane. To stabilize the activity of the sensing platinum electrode, a fast-pulsing reactivation method was applied. Good performance of the continuously operating sensor was achieved in buffer (10% stability of the baseline current within 12 days) and human ultrafiltrate (10% stability of the baseline current and 5% stability of the sensitivity within 7 days). However, for measurements in plasma a slow degradation of the sensor's sensitivity (approximately 10% per day) was observed. These results indicate that when a proper screening membrane is provided the continuous glucose monitoring of body fluids with the miniature sensor is possible for at least 7 days.

Animals↗
PubMedDate not supplied

Removal of trypsin complexed alpha-2 macroglobulin by plasma fractionation.

The aim of this study is to assess in vitro the efficacy of a plasma fractionator to remove trypsin complexed alpha 2MG (alpha-2 macroglobulin) from human plasma in a manner analogous to the reticuloendothelial system (RES). Eval filter type "4A" (Kuraray Co., Osaka, Japan) was chosen as a plasma fractionator. Two and one half liters of bovine trypsin spiked human plasma was perfused in vitro through the fractionator in a single pass mode (n = 5). The concentrations of complexed alpha 2MG, total alpha 2MG, albumin, and IgM were measured before and after fractionation, and the concentration of free alpha 2MG and the sieving coefficients of each solute were calculated. The concentration of the trypsin complexed alpha 2MG measured by ELISA was significantly decreased by fractionation with Eval "4A" from 103.7 +/- 16.7 to 13.8 +/- 8.2 mg/L (reduction of 86.7%). Mean sieving coefficients of each solute were 0.133 +/- 0.079 in complexed alpha 2MG, 0.203 +/- 0.065 in free alpha 2MG, 0.203 +/- 0.065 in total alpha 2MG, 0.770 +/- 0.130 in albumin, and 0.070 +/- 0.010 in IgM. Although in vivo study will be required in patients with acute pancreatitis, in vitro study shows the feasibility of membrane plasma fractionation in eliminating trypsin complexed alpha 2MG.

Acute Disease↗
PubMedDate not supplied

Experimental study of extracorporeal perfusion for septic shock.

The authors evaluated the efficacy of treatment by extracorporeal perfusion on experimental canine septic shock. Canine septic shock was produced by intravenous infusion of Escherichia coli endotoxin and treated by three techniques: no treatment (Sham), hemoperfusion over Polymyxin B immobilized fiber (PMX), and plasma perfusion over anion exchange resin (Resin). The 24 hr survival rates of the Sham, PMX, and Resin groups were 0%, 80%, and 40%, respectively. In the PMX group, blood pressure was significantly better over 6 hr than that recorded in the Sham group. In the PMX group, phagocytic function evaluated by neutrophil function, opsonic index, and complement were better than that of the Sham group. In addition, blood endotoxin levels in the PMX group were significantly lower, resulting in a significant suppression of TNF release. In the Resin group, some parameters were significantly better than those of the Sham group, but the efficacy of this treatment was less than that of the PMX treatment. Hemoperfusion over Polymyxin B immobilized fibers can detoxify circulatory endotoxin, resulting in improvement of systemic and organic disorders caused by sepsis.

Animals↗