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PubMed1997

Improved dextran preparation of human leucocytes for chemiluminescence analysis of the oxidative burst of polymorphonuclear cells.

An improved method for the preparation of leucocyte-rich plasma from human blood samples for chemiluminescence (CL) analysis is described. Heparinized blood is layered over 4% dextran in a ratio of 1:1 (v/v). The leucocyte-rich plasma is obtained after a 1 h sedimentation of the erythrocytes. When compared with the plasma obtained by the usual method of mixing blood with dextran, the residual red cell count was reduced. On the other hand, the index of phagocytosis (peak values of activated phagocytosis/spontaneous phagocytosis) was increased. This is caused by increased spontaneous CL activity after mixing blood with dextran, which can activate leucocytes. Such activation was observed both in plasma samples and in whole blood samples when measured immediately after dextran addition or after 1 h incubation with dextran.

Dextrans↗

PubMedDate not supplied

A prospective study of the effect of dextran administration on compatibility testing.

The effects of dextran therapy on pretransfusion compatibility testing were evaluated in 24 patients with a variety of vascular disorders. Specimens were drawn before, during, and after the administration of low-molecular-weight dextran (average molecular weight, 40 kd). Forty-three specimens were studied extensively with several immunohematologic techniques. Dextran levels were measured to determine whether the concentration influenced the results of serologic tests. In no instance could we demonstrate any interference by dextran with pretransfusion tests, even at high serum levels of dextran.

Blood Banks↗

PubMed2001

Dextran sedimentation in a semi-closed system for the clinical banking of umbilical cord blood.

BACKGROUND: The results of current processing procedures for reducing volume and recovering HPCs from umbilical cord blood (UCB) before cryopreservation vary. STUDY DESIGN AND METHODS: Dextran was added to bags containing UCB, followed by sedimentation for 30 minutes. The processed UCB was then frozen. RBCs, nucleated cells, MNCs, CD34+ cells, CFUs and long-term culture-initiating cells (LTC-ICs), viability, and sterility were evaluated. Fractionations in ficoll-hypaque and hydroxyethyl starch (HES) were also run in parallel for comparison. RESULTS: The nucleated cell (NC) recovery and RBC depletion were 86.1 percent and 94.3 percent, respectively (n = 50). Sedimentation with dextran also enabled the recovery of 80.7 percent MNCs and 82.6 percent CD34+ cells (n = 30). Postsedimentation samples displayed no impairment of CFU growth (n = 42, 108.7% CFU-C, 104.6% CFU-GEMM, 107% CFU-GM, and 95.7% BFU-E). Long-term cultures on five paired samples before and after sedimentation generated similar numbers of CFU-C each week (p = 0.88). Limiting dilution analysis of 12 paired pre/postsedimentation samples showed comparable median proportions of LTC-ICs (1/6494 vs. 1/5236; p = 0.18). The cell viability of 24 samples of thawed UCB after sedimentation was 90.3 percent (77.5-96%) and the recovery of CFU-C, CFU-GEMM, CFU-GM, and BFU-E of 11 postsedimentation samples was 93.4 percent, 84.9 percent, 92.3 percent, and 83.4 percent, respectively. NC recovery was significantly higher after treatment with dextran than with ficoll-hypaque (n = 30; 88.5% vs. 29.1%; p<0.005) and HES treatment (n = 21; 88.5% vs. 76.4%; p = 0.004). However, MNCs, CD34+ cells, CFUs, LTC-ICs, and RBCs were comparable. Two cycles of dextran sedimentation recovered 93.9 percent of NCs with cell viability of 98.6 percent (96.5-100%), whereas 11.7 percent of RBCs were retained (n = 20). The final yield volume was 33.5 (28-41) mL. CONCLUSION: In a semi-closed system, dextran sedimentation enabled volume reduction of UCB without significant quantitative and qualitative losses of HPCs.

Blood Banks↗

PubMed1998

A randomized trial of three iron dextran infusion methods for anemia in EPO-treated dialysis patients.

Forty-three hemodialysis patients receiving recombinant erythropoietin (rHuEPO, epoietin alpha) were randomized to receive intravenous iron dextran as a total-dose infusion, 500-mg infusion to total dose, or 100-mg bolus to total dose, in each case during the dialysis procedure. The dose of iron dextran was calculated from the patient's existing hemoglobin to achieve a desired hemoglobin. Patients were eligible to receive intravenous iron dextran if they had a serum ferritin of < or = 100 ng/mL or a serum ferritin of 100 to 200 ng/mL, along with a transferrin saturation of < or = 19%. Patients were excluded if they had prior therapy with iron dextran, aluminum intoxication, or transfusion during the study. The time to the maximum hemoglobin, acute adverse reactions, and delayed adverse reactions were analyzed statistically, and no differences were seen in any of the three groups. Total-dose intravenous iron dextran infusion is safe, convenient, less expensive, and as efficacious as divided-dose infusions.

Anemia↗

PubMed2001

Low molecular weight heparin (enoxaparin) versus dextran in the prevention of early occlusion following arterial bypass surgery distal to the groin.

AIM: to compare the effect of perioperative dextran and low molecular weight heparin on early graft patency after femorodistal bypass surgery. DESIGN: prospective randomised multicentre study. PATIENTS AND METHODS: three hundred and fourteen patients were randomised to dextran 70 or the low molecular weight heparin enoxaparin during and after femorodistal bypass surgery. Patency was evaluated at days 1, 5-7, 30 and 90. RESULTS: there was no difference in patency at any time point between the two regimens, the crude 90 days patency being 88 and 83%, respectively. There were significantly more patients with heart failure in the dextran group (12.8 vs 0.7%), with other side effects being evenly distributed. CONCLUSION: dextran 70 and the low molecular weight heparin enoxaparin have the same effect on 90 days femorodistal graft patency, but care must be taken using the dextran to patients with a potential heart insufficiency.

Anticoagulants↗

PubMed1976

[Treatment of acute cerebral ischaemia with low-molecular dextran: results of a retrospective study (author's transl)].

Between 1968 and 1970, 226 patients with acute cerebral ischaemia were treated with vasodilator drugs. In the subsequent three years (1971 to 1973) 202 patients were instead treated with dextran (Rheomacrodex) infusions. tin the latter period the death-rate was 35%, 19% less than during the preceding period of vasodilator treatment. In the dextran group among patients over 65 years the death-rate was 42%, 21% less than in the vasodilator group of the same age. Dextran treatment caused complete disappearance of neurological signs in 25%, compared with 7.5% in the vasodilator group. Dividing patients into those with normal blood pressure, hypertension and diabetes gave corresponding differences among the two groups. The death-rate during the period of dextran treatment was significantly less in all the sub-groups than in the vasodilator years. The results of this retrospective study provide important pointers to the effectiveness of dextran infusion in the treatment of acute cerebral ischaemia.

Aged↗

PubMed1994

Reaction of germinal centers in the T-cell-independent response to the bacterial polysaccharide alpha(1-->6)dextran.

Primary immunization of BALB/c mice with alpha(1-->6)dextran (DEX), a native bacterial polysaccharide, induces an unexpected pattern of splenic B-cell responses. After a peak of antibody-secreting B-cell response at day 4, deposition of dextran-anti-dextran immune complexes, as revealed by staining with both dextran and antibodies to dextran, occurs and persists in splenic follicles until at least the fourth week after immunization. Antigen-specific B cells appear and proliferate in such follicles, leading by day 11 to development of DEX-specific germinal centers as characterized by the presence of distinct regions of DEX+ peanut agglutinin-positive (PNA+) cells. At this time, fluorescence-activated cell sorter analysis also reveals the appearance of a distinct population of DEX+ PNA+ splenic B cells. In contrast, DEX+ PNA- cells, characterized by intense cytoplasmic staining, are present outside of splenic follicles, peak at day 4 to day 5, and persist until at least day 28. The frequency of these cells correlates with DEX-specific antibody-secreting cells, as detected by the ELISA-spot assay. Thus, in addition to the expected plasma cellular response, the typical T-cell-independent type II antigen, DEX, surprisingly also elicits the formation of antigen-specific germinal centers. These observations raise fundamental questions about the roles of germinal centers in T-cell-independent immune responses.

Animals↗

PubMed2003

A comparative study between intramuscular iron dextran and oral ferrous sulphate in the treatment of iron deficiency anaemia in pregnancy.

A comparative study was conducted to demonstrate the difference, if any, in effectiveness of treatment of iron deficiency anaemia in pregnancy with either iron dextran or ferrous sulphate. Sixty pregnant women with iron deficiency anaemia were assigned randomly to either group and treated for 6 weeks. The age and parity distributions with mean packed cell volumes (PCVs) and gestational age at onset of treatment in the two groups were comparable. Comparing the mean PCVs at week 2, week 4 and week 6 of treatment the iron dextran group recorded higher and statistically significant mean PCVs (P<0.001). Thirty-six per cent of patients in the iron dextran group compared to 3.3% in the oral iron group (P=0.004) had their anaemia corrected by the sixth week. No significant side effects accompanied the use of intramuscular iron dextran. It was concluded that iron dextran corrects iron deficiency anaemia faster than ferrous sulphate. Parenteral iron should be considered in pregnant woman with moderate and asymptomatic severe anaemia between gestation ages of 28 weeks and 34 weeks; this may reduce the frequency of blood transfusion both in the antenatal and postnatal periods in these patients.

Administration, Oral↗

PubMed2005

Drug release from core-shell type nanoparticles of poly(DL-lactide-co-glycolide)-grafted dextran.

This study prepared core-shell type nanoparticles of a poly(DL-lactide-co-glycolide) (PLGA) grafted-dextran. The synthesis of the PLGA-dextran conjugate was confirmed by Fourier transform-infrared (FT-IR) spectroscopy. The PLGA grafted-dextran was able to form nanoparticles in water by self-assembly and their particle size was 245.3 +/- 95.1 nm. From fluorescence probe study using pyrene as a hydrophobic probe, critical association concentration (CAC) values were determined from the fluorescence excitation spectra and were found to be 0.006 g l(-1). Morphological observations using a scanning electron microscope (SEM) showed that the polymeric nanoparticles of the PLGA-dextran conjugate have uniformly spherical shapes. Their size and morphology provide them with acceptable properties for use as a drug-targeting carriers. Drug release from core-shell type nanoparticles was faster in the presence of dextranase, indicating that core-shell type nanoparticles of PLGA grafted-dextran can be used as an oral drug carriers.

Administration, Oral↗

PubMed1982

Charcoal as a phase separating agent in ligand assays: mechanism of action and the effect of dextran and various proteins on the adsorption of of small molecules.

In ligand assays, charcoal mixed with dextran is sometimes used to separate free from bound ligand. This is done with the view that dextran "coats" the charcoal and produces a sieve effect on its surface. To further elucidate the mechanism of differential adsorption of small molecules to charcoal, studies were made on the interaction between a number of commonly measured ligands and charcoal, either unmixed or mixed with dextran, albumin, immunoglobulin (IgG) or insulin. "Coating" with dextran was shown not to have any effect on subsequent adsorption of the various ligands. However, coating charcoal with albumin, IgG or insulin did have an effect and even augmented subsequent adsorption of small molecules under certain conditions. It is concluded that the use of "dextran coating" of charcoal to give a sieve effect for the separation of small molecules from large ones is unnecessary and has no basis in fact. This is not the case for coating charcoal with proteins.

Animals↗

PubMed1995

Resting cytoplasmic free Ca2+ concentration in frog skeletal muscle measured with fura-2 conjugated to high molecular weight dextran.

Intact frog skeletal muscle fibers were injected with the Ca2+ indicator fura-2 conjugated to high molecular weight dextran (fura dextran, MW approximately 10,000; dissociation constant for Ca2+, 0.52 microM), and the fluorescence was measured from cytoplasm (17 degrees C). The fluorescence excitation spectrum of fura dextran measured in resting fibers was slightly red-shifted compared with the spectrum of the Ca(2+)-free indicator in buffer solutions. A simple comparison of the spectra in the cytoplasm and the in vitro solutions indicates an apparently "negative" cytoplasmic [Ca2+], which probably reflects an alteration of the indicator properties in the cytoplasm. To calibrate the indicator's fluorescence signal in terms of cytoplasmic [Ca2+], we applied beta-escin to permeabilize the cell membrane of the fibers injected with fura dextran. After treatment with 5 microM beta-escin for 30-35 min, the cell membrane was permeable to small molecules (e.g., Ca2+, ATP), whereas the 10-kD fura dextran only slowly leaked out of the fiber. It was thus possible to estimate calibration parameters in the indicator fluorescence in the fibers by changing the bathing solution [Ca2+] to various levels; the average values for the fraction of Ca(2+)-bound indicator in the resting fibers and the dissociation constant for Ca2+ (KD) were, respectively, 0.052 and 1.0 microM. For the comparison, the KD value was also estimated by a kinetic analysis of the indicator fluorescence change after an action potential stimulation in intact muscle fibers, and the average value was 2.5 microM. From these values estimated in the fibers, resting cytoplasmic [Ca2+] in frog skeletal muscle fibers was calculated to be 0.06-0.14 microM. The range lies between the high estimates from other tetracarboxylate indicators (0.1-0.3 microM; Kurebayashi, N., A. B. Harkins, and S. M. Baylor. 1993. Biophysical Journal. 64:1934-1960; Harkins, A. B., N. Kurebayashi, and S. M. Baylor. 1993. Biophysical Journal. 65:865-881) and the low estimate from the simultaneous use of aequorin and Ca(2+)-sensitive microelectrodes (< 0.04-0.06 microM; Blatter, L. A., and J. R. Blinks. 1991. Journal of General Physiology. 98:1141-1160) recently reported for resting cytoplasmic [Ca2+] in frog muscle fibers.

Animals↗

PubMed1992

Dextran-coupled deferoxamine improves outcome in a murine model of head injury.

Tissue damage involving oxygen-derived free radicals may be greatly exacerbated by free, reactive iron, which acts as a catalyst in oxidative reactions. The effects of free iron can be attenuated by the administration of deferoxamine (DFO), an iron chelator. However, DFO has limited therapeutic utility because it has a short plasma half-life (approximately 5.5 min in mice) and produces profound hypotension upon intravenous infusion. These negative attributes have been circumvented by the covalent attachment of DFO to large polymers, such as dextran or hydroxyethyl starch. The ability of the dextran-conjugated DFO (DEX-DFO) to inhibit iron-catalyzed reactions with lipids was compared to that of the native molecule in an in vitro model of CNS lipid degradation in the presence of 200 microM ferrous iron. There was no difference between native DFO and the modified form. Modified and unmodified DFO were also compared for therapeutic efficacy in a murine model of head injury. Using a previously described "grip test" as a measure of neurologic impairment following injury, DEX-DFO, native DFO, and dextran were administered intravenously 3-5 min after injury. Dextran-DFO significantly decreased the incidence of severe neurologic impairment at dosage levels of 0.1 (n = 92), 1.0 (n = 76), and 10.0 (n = 80) mg/kg. Administration of native DFO or dextran had no effect at the same dosages and concentrations. These results suggest that the murine model of head injury contains a significant iron-dependent component that should be assessed in other models of neural injury.

Animals↗

PubMed1976

Histamine release in human subjects by modified gelatin (Haemaccel) and dextran: an explanation for anaphylactoid reactions observed under clinical conditions?

Histamine release by modified gelatin (Haemaccel) and dextran (Macrodex) has been demonstrated in volunteers by direct and indirect methods. In a pilot study of Haemaccel, histamine release was observed in six of seven volunteers. The highest plasma histamine concentration was 4.8 ng/ml, the lowest 1.7 ng/ml: two of the subjects showed slight allergic reactions. Using Haemaccel batch 2551, 10 out of 12 subjects reacted to the rapid infusion of Haemaccel with increased plasma histamine concentrations, whereas none reacted to Ringer's solution. None of the 10 subjects had an allergic reaction, but an increase in gastric secretion was observed in eight. Changes in the venous basophil granulocyte count were found in both those who reacted and those who did not react to Haemaccel. After the rapid infusion of dextran the highest plasma histamine concentration was 5.0 ng/ml, the lowest 1.3 ng/ml. The withdrawal of blood had no influence on plasma histamine concentration. The incidences of histamine release produced by Haemaccel varied with different batches. Thus, it seems unlikely that immunological mechanisms are principally responsible. Nine instances of allergic and anaphylactoid reactions to plasma substitutes have been reported, seven after Haemaccel infusion, and two after dextran administration. One of the patients who received dextran died. Histamine release was always associated with Haemaccel infusion and corresponded in extent to the clinical symptoms observed, but there was no significant histamine release associated with the reactions to dextran.

Adult↗

PubMed1997

Characterization of nephropathy induced by immunization with high molecular weight dextran.

BACKGROUND: Injection of DEAE dextran into Lewis rats can produce proteinuria and has been reported as a model of IgA nephropathy. METHODS: Cationic diethyl aminoethyl (DEAE) dextran of molecular weight 500 kDa was injected into male Lewis rats. After a pre-immunization period of 3 weeks, the animals were divided into two groups: group 1 (n = 14) received daily i.v, injections of 3.5 mg of antigen, group 2 (n = 14) was injected with 1.5 mg three times per week for a total period of 6 weeks. I.v. treatment was initiated with gradually increasing doses of DEAE dextran in both groups for 1 week, after which the maintenance dose was reached. RESULTS: We observed the appearance of proteinuria in a nephrotic range after 5 weeks of i.v. injections in group 1 (urinary excretion: 332 +/- 83 mg/24 h, controls: 53 +/- 14 mg/24 h). In group 2, the proteinuria was almost equal to protein excretion of healthy rats of the same weight (67 +/- 20 mg/24 h). The serum and urine creatinine were normal. By light microscopy of kidney biopsies, the presence of focal and segmental proliferation of mesangial cells after 6 weeks of i.v. injections was identified. Immunohistochemistry revealed no deposition of IgA, IgM, IgG, or C3. Using anti-ED1 antibodies, there was no evidence of interstitial infiltration of monocytes/macrophages after 6 weeks of i.v. injections. Staining for proliferating cell nuclear antigen (PCNA) did not show the presence of proliferating cells either in glomeruli or in the interstitium. Staining with FITC-WGA lectin revealed focal and segmental loss of the negative charge in the capillary wall. By electron microscopy there was deposition of dextran in the basal membrane and segmental and focal damage of the podocyte foot processes. As the chemokine RANTES may be involved in glomerular injury, we examined the kidneys of proteinuric and non-proteinuric rats for the presence of RANTES. By indirect immunofluorescence only the proteinuric rats showed RANTES deposition in the mesangium. CONCLUSIONS: Injection of rats with DEAE dextran leads to dose-dependent proteinuria without deposition of immune complexes but with podocyte damage. This is associated with local expression of the chemokine RANTES which may play a role in proteinuria of glomerular disease.

Animals↗

PubMed1997

Cationic dextran induces mesangioproliferative nephritis in rats independent of glomerular IgA deposition.

BACKGROUND: Dextran-induced mesangioproliferative glomerulonephritis in mice and, as recently reported, in rats is used as a model of IgA nephropathy. The pathogenetic role of the glomerular IgA deposits in this model, however, is unclear since IgG is often deposited in parallel. METHODS: Lewis rats were immunized with cationic DEAE-dextran. Following this, rats received 5 x/week i.v. injections of 3 mg DEAE-dextran each, from days 20 to 80 and were then followed until day 120. RESULTS: Rats developed transient proteinuria (range 63-152 mg/24 h) and haematuria on day 80. Renal biopsies obtained at days 60, 80, 100 and 120 showed mild to severe mesangioproliferative changes at days 80 and 100 which did not persist at day 120. Electron-microscopy revealed mesangial immune deposits, signs of endothelial activation and vacuoles in mesangial cells and podocytes. Compared to normal, age-matched controls, in the nephritic rats significant (P < 0.05) increases were noted for glomerular total cellularity, alpha-smooth-muscle actin expression (a marker of activated mesangial cells), monocyte/macrophage counts, and matrix proteins. Using three different antibodies, no evidence of glomerular IgA deposition was detected at any time point. In contrast, glomerular IgG, IgM, C3, and occasional small C5b-9 deposits were present in nephritic rats. Circulating IgG but not IgA anti-dextran antibodies could be demonstrated in nephritic rats. CONCLUSIONS: The data confirm that mesangioproliferative glomerulonephritis can be induced in rats by immunization and chronic challenge with cationic dextran. Our data also show that in rats glomerular IgG deposition rather than IgA, appears to play an important pathogenetic role in this mesangioproliferative glomerulonephritis model.

Animals↗

PubMed2002

Acute renal failure during dextran-40 antithrombotic prophylaxis: report of two microsurgical cases.

Dextran is often used to enhance the successful outcome of microvascular transplantations. So far, some 60 cases of dextran-induced acute renal failure have been reported. Among them, only one has been reported as an adverse reaction to antithrombotic prophylaxis during microvascular surgery. To stress that dextran prophylaxis can be a serious threat to microsurgical patients, the authors report on two more such patients and discuss how to prevent and treat this condition. Hypovolemic patients of older age are at risk, as are patients with cardiovascular diseases, renal artery stenosis, and preexisting renal insufficiency. Dextran should be discontinued promptly in patients with decreased urinary output or with high urine specific gravity. Dextran-induced acute renal failure may be severe and it may last several days. Plasmapheresis is the therapy of choice and, usually, diuresis and renal function resume shortly after such treatment.

Acute Kidney Injury↗

PubMed1979

Effect of dextran on factor VIII (antihemophilic factor) and platelet function.

Three different properties of factor VIII (antihemophilic globulin) were studied after infusion of 500 ml of six per cent Dextran 70 to healthy volunteers. This dose caused no change in the factor VIII coagulant activity while there was a significant but temporary decrease of factor VIII related antigen. The Ristocetin induced platelet aggregation analysed with native as well as with formalin-fixed platelets, also decreased significantly. The maximal decrease was found a few hours after the infusion. The decrease was seen only if Dextran was infused in vivo and not if Dextran was added to blood in vitro. The dysfunction of factor VIII caused by Dextran resembles that found in one variant of von Willebrand's disease. This finding probably explains the platelet function inhibiting properties of Dextran, and may be of significance for its antithrombotic effects.

Adolescent↗

PubMed2000

Intraperitoneal injection of dextran sulfate as an anti-adherent drug for the prevention of peritoneal metastasis of cancer shows low toxicity in animals.

Intraperitoneal dextran sulfate with a mean molecular weight of 5 x 10(5) has been developed for use in an anti-adherent therapy against peritoneal carcinomatosis. The present study examined acute toxicity of i.p. injection of dextran sulfate in mice and rabbits. The 10, 50 and 90% lethal dose values are 0.213 (0.146-0.252), 0.336 (0.291-0.405) and 0.530 mg/g (0.431-0.873 mg/g: 95% confidence interval) in mice, respectively. These are markedly larger than the efficacious dose of 0.005-0.01 mg/g obtained previously. Death or symptoms of intoxication were seen within 3 days after administration of toxic doses. Rabbits received i.p. injection of dextran sulfate at 0.02 mg/g, which was close to the efficacious dose. At 2, 4, 6, 8 and 13 days after administration, blood was taken for biochemical and hematological analyses. Dextran sulfate at 0.02 mg/g induced no remarkable abnormal findings. These results suggest that the i.p. dextran sulfate is safe as an anti-adherent agent against peritoneal metastasis of cancer.

Animals↗