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PubMed1991

Anaphylactic reaction because of intrauterine 32% dextran-70 instillation.

Anaphylactic reaction associated with hysteroscopy using 32% dextran-70 as a distending medium is a rare phenomenon. We report anaphylactic reaction associated with hysteroscopy using dextran that was delivered manually in three otherwise healthy women occurring within a 6-month period. The rapidity and pressure of dextran administered might facilitate intravascular absorption and predispose patients to this phenomenon.

Adult↗
PubMed1996

Randomized trial comparing albumin, dextran 70, and polygeline in cirrhotic patients with ascites treated by paracentesis.

BACKGROUND & AIMS: Paracentesis associated with plasma expanders is widely used for the treatment of ascites in cirrhosis. This study investigated the clinical importance of paracentesis-induced-circulatory dysfunction and compared the efficacy of albumin, dextran 70, and polygeline in preventing this complication. METHODS: A total of 289 cirrhotic patients with ascites were randomized to treatment by total paracentesis plus intravenous albumin (97 patients), dextran 70 (93 patients), or polygeline (99 patients). Postparacentesis circulatory dysfunction was defined as an increase in plasma renin activity on the sixth day after paracentesis of more than 50% of the pretreatment value to a level > 4 ng.mL-1.h-1. RESULTS: Postparacentesis circulatory dysfunction occurred more frequently in patients treated with dextran 70 (34.4%; P = 0.018) or polygeline (37.8%; P = 0.004) than in those receiving albumin (18.5%). The plasma expander used and the volume of ascites removed were independent predictors of this complication. Postparacentesis circulatory dysfunction persisted during follow-up and was associated with a shorter time to first readmission (1.3 +/- 0.5 vs. 3.5 +/- 0.8 months, median +/- SEM; P = 0.03) and shorter survival (9.3 +/- 4.2 vs. 16.9 +/- 4.3 months; P = 0.01). Creatinine and sodium levels in serum, and Child-Pugh score at inclusion, and postparacentesis circulatory dysfunction were independent predictors of survival. CONCLUSIONS: Postparacentesis circulatory dysfunction is not spontaneously reversible and is associated with a shorter time to first readmission and shorter survival. Albumin is the best plasma expander to prevent this complication.

Adult↗
PubMed1979

Affinity partition of proteins in aqueous two-phase systems containing polyoxyethylene glycol-bound ligand and charged dextrans.

The partition of the delta 5 leads to 4 3-oxosteroid isomerase of Pseudomonas testosteroni in aqueous two-phase systems containing both the macroligand, polyoxyethylene glycol-bound estradiol, and charged (cationic or anionic) dextrans has been studied. If the enzyme is well retained in the upper phase by an adequate amount of macroligand, it is possible to improve the removal of the contaminating proteins by extracting them into a lower phase containing positively or negatively charged dextran. Some mult-step extraction experiments were carried out to purify isomerase, by washing the upper phase successively with cationic and anionic dextran-rich phases.

Anions↗
PubMed1998

A novel method for DEAE-dextran mediated transfection of adherent primary cultured human macrophages.

Primary cultured human macrophages are difficult to transfect. We have developed a DEAE-dextran DNA transfection method that mediates the reproducible transfection of primary cultured adherent human macrophages. Three factors essential for successful transfection were identified: DEAE-dextran concentration, the quantity of DNA per transfection and the incubation time of the macrophages with the transfection medium. Maximum levels of luciferase expression were attained within 24 h and maintained for at least 56 h after transfection. While serum in the transfection medium attenuated transfection, the treatment of the macrophages with chloroquine, DMSO, or glycerol did not enhance transfection within this system. A CMV enhancer/promoter mediated substantially greater luciferase expression in the macrophages than either HIV or RSV LTRs. DEAE-dextran facilitated superior transfection compared to either cationic liposome and calcium phosphate methods, and was more practical compared to electroporation for multiple transfections. This transfection protocol provides a simple, inexpensive, reproducible method for the evaluation of gene expression in primary cultured adherent human macrophages.

Adult↗
PubMed1998

Detection of low-affinity adhesion ligands by linking recombinant cell adhesion molecules in uniform orientation to a fluorescently labelled dextran molecule by means of hexahistidine tagging: the case of multimeric CD40.

Cell-cell interactions involve highly polyvalent associations between receptors on adjacent cells. In order to mimic this process, we have prepared a highly polyvalent form of CD40 attached to a dextran backbone. This was accomplished by engineering a hexahistidine tag on the C-terminus of the CD40 and binding, in a uniform orientation, up to 100 molecules of hexahistidine CD40 by metal chelation to a single fluorescently tagged dextran molecule. The advantage of this 'multimeric' CD40 is that it would be expected to bind to any counterstructure with a significantly higher avidity compared to monomeric CD40. The multimeric CD40 bound with high affinity to stably transfected mouse fibroblasts expressing CD40L. The multimeric ligand also bound to the activated T cell clone, D10, but did not bind to resting cells, showing that it bound to the physiological ligand. Using this system, we found no evidence to support the claim [Heath et al., 1993. Cell. Immunol. 152, 468.] that the A20 cells have a counterstructure for CD40, and propose that the high binding of CD40 observed in this study may have been due to an exposed hexahistidine tag on the molecule. This multimeric technology has considerable potential for detecting low-affinity interactions between cell adhesion receptors and ligands. The uniform orientation of the molecules on the dextran is an advantage over previous systems and permits the preparation of heterogeneous, multimeric ligands which more closely mimic the conditions at the cell surface.

3T3 Cells↗
PubMed1999

Orally administered dextran sulfate is absorbed in HIV-positive individuals.

Preliminary in vivo studies suggested that oral dextran sulfate was poorly absorbed, but investigations were limited by inadequate methods for measuring the drug in the body. To determine absorption in HIV-positive subjects, hydrogenated dextran sulfate, average molecular weight 8000 (Usherdex 8), was orally administered in a short-term (single dose, 4 g/day for 5 days, 7 subjects) and in a long-term study (1 g, 4 times per day for 29 to 335 days, 8 subjects), which was a continuation of the short-term study with the inclusion of an additional subject. When an agarose gel electrophoresis technique with toluidine blue staining was used, the drug was recovered from plasma (67%, peak 2.2 microg/mL) and circulating peripheral blood lymphocyte (PBL) samples (50%, peak 333 microg/L blood) obtained at 5 and 15 minutes and 1, 3, 6, and 24 hours after the first day's dose and from plasma (56%) and PBL samples (38%) obtained 5 minutes after administration on 4 subsequent days in the short-term study. In the long-term study, the drug was found in plasma (67%, peak 2.4 microg/mL) and PBL samples (25%, peak 126 microg/L blood) obtained at monthly visits within 4 hours of the last dose. The drug was found in all urine samples from all subjects in both studies (short-term study, 24-hour samples up to 4 days after the final dose; long-term study, monthly samples within 4 hours of the last dose). In the long-term study, bone marrow preparations from 3 subjects showed metachromatic inclusions present in reticular cells when the cells were stained with toluidine blue, indicating the presence of sulfated polyanions. A significant rise in activated partial thromboplastin time and a drop in platelet count (P < .025) were demonstrated, with thrombocytopenia developing in 3 patients. Mild-to-moderate gastrointestinal disturbances were experienced by 6 subjects in the short-term study and by all subjects in the long-term study. One subject experienced mild central nervous system symptoms in the short-term study. These results indicate that dextran sulfate is absorbed after oral administration; therefore, further studies on its efficacy, particularly in the early stages of the disease, along with additional observations on its toxicity, are warranted.

Absorption↗
PubMed1999

Dextran sulfate inhibits E-selectin-mediated neutrophil adhesion to endotoxin-activated vascular endothelial cells.

Effects of heparin-like glycosaminoglycans (h-GAGs) on neutrophil adhesion to endothelial cells (ECs) were investigated under physiological flow conditions using human umbilical vein ECs. Neutrophil adhesion to lipopolysaccharide-activated ECs was assayed under rotating conditions with addition of h-GAGs or monoclonal antibodies (mAbs) against selectins. Neutrophil adhesion to activated ECs under rotating conditions was suppressed completely by anti-E-selectin mAb and partially by anti-L-selectin mAb. Addition of dextran sulfate or heparin also significantly inhibited neutrophil adhesion to ECs under the same conditions. Moreover, effects of h-GAGs on neutrophil adhesion to recombinant E-selectin-coated plates were analyzed. Anti-E-selectin mAb and dextran sulfate, but not heparin, significantly inhibited neutrophil adhesion to E-selectin-coated plates. Results suggest that dextran sulfate inhibited E-selectin-mediated neutrophil adhesion to endotoxin-activated ECs under physiologic flow conditions.

Antibodies, Monoclonal↗
PubMed1982

Failure of serum ferritin levels to predict bone-marrow iron content after intravenous iron-dextran therapy.

The relation between serum ferritin levels and stainable-iron deposits in the liver, spleen, and bone marrow was investigated in 36 patients with chronic renal failure who died after being on haemodialysis for 1-103 months. Elemental iron (mean, 5450 mg) had been given intravenously as iron dextran to patients in a long-term subgroup, who had been on dialysis for more than 3 months. The results of semiquantitative histochemical assessment of tissue iron in slides obtained at necropsy (scale 0 to 4+) were confirmed by chemical analyses of tissue iron. Serum ferritin levels correlated well with the degree of hepatosplenic siderosis but did not always correlate with bone-marrow iron stores in these patients. Serum ferritin concentrations were raised in 10 marrow-iron-depleted subjects (mean, 1336 ng/dl). The paradoxical association of hepatosplenic siderosis with marrow iron depletion was observed in most of the patients on dialysis for less than 40 months. The histochemical data show that the bulk of intravenously injected iron dextran is taken up by the liver and spleen; that the hepatosplenic stores fail to be mobilised to the bone marrow; and that intravenous iron-dextran therapy, by-passing the intestinal mechanism for the regulation of iron absorption, carries a high risk of long-term hepatosplenic siderosis.

Aged↗
PubMed2003

Biodegradable hydrogels obtained by photocrosslinking of dextran and polyaspartamide derivatives.

The functionalization of dextran with glycidyl methacrylate (GMA) leads to the formation of a derivative that generates hydrogels for irradiation at 365nm. The effects of various polymer concentrations and irradiation times on the yield and the properties of the obtained hydrogels are reported. The networks have been characterized by FT-IR spectra, dimensional analysis and swelling measurements carried out at different pH values. In vitro studies suggest that all samples undergo a partial chemical hydrolysis, whereas the incubation with dextranases causes a total degradation whose rate depends on the degree of crosslinking. In addition, aqueous solutions of functionalized dextran have been irradiated in the presence of PHG (PHEA-GMA), i.e. the copolymer obtained by the reaction of alpha,beta-poly(N-2-hydroxyethyl)-DL-aspartamide (PHEA) with GMA. The crosslinking reaction leads to the formation of new networks containing both polymers whose properties have been investigated. To evaluate the processes which occur during UV irradiation, the sol fractions have been purified and characterized by FT-IR and 1H-NMR analyses. Finally, the suitability of hydrogels deriving from functionalized dextran, crosslinked alone or in the presence of PHG, for drug delivery systems has been investigated choosing theophylline as a model drug.

Biocompatible Materials↗
PubMed1998

In vitro and in vivo biocompatibility of dextran dialdehyde cross-linked gelatin hydrogel films.

The biosafety of a new hydrogel wound dressing material consisting of dextran dialdehyde cross-linked gelatin was evaluated (i) in vitro in cultures of dermal fibroblasts, epidermal keratinocytes, and endothelial cells, three cell types which play a major role in the process of cutaneous wound healing, and (ii) in vivo by subcutaneous implantation studies in mice. The cytotoxicities of this hydrogel, two semi-occlusive polyurethane dressings (Tegaderm and OpSite), and a hydrocolloid dressing (DuoDERM) were compared by measuring cell survival with the tetrazolium salt reduction (MTT) assay after incubations of the wound dressing samples for up to 6 d, in the presence of--but not in direct contact with--the cells. In vitro, the degree of cytotoxicity of the new hydrogel was greater in keratinocyte cultures than in fibroblast and endothelial cell cultures, and increased upon longer incubation time. In keratinocyte cultures, the semi-occlusive polyurethane dressings, the hydrocolloid, and the hydrogel dressings induced low, high and acceptable degrees of cytotoxicity, respectively. The toxicity of the isolated hydrogel components was assessed in Balb MK keratinocyte cultures. In these cells, epidermal growth-factor-stimulated thymidine incorporation into DNA was higher in the presence of gelatin. By contrast, concentrations of dextran dialdehyde as low as 0.002% were found to significantly decrease thymidine incorporation (P < 0.01). Subcutaneous implantation studies in mice showed that in vivo the hydrogel was biocompatible since the foreign body reaction seen around the implanted hydrogel samples was moderate and became minimal upon increasing implantation time. These results indicate that dextran dialdehyde cross-linked gelatin hydrogels have an appropriate biocompatibility.

3T3 Cells↗
PubMed2001

Comparison of wheat germ agglutinin-horseradish peroxidase and biotinylated dextran for anterograde tracing of corticospinal tract following spinal cord injury.

Established methods for monitoring regeneration of the corticospinal tract involve anterograde labelling of the cortical motor neuron. While wheat germ agglutinin-horseradish peroxidase conjugate has been used to anterogradely label these neurons, we demonstrate that this technique may not completely label the whole axon and fine terminal processes when this tracer is administered in dried form. An alternative method is described for anterograde labelling of cortical motor neurons using biotinylated dextran. This tracer may be applied by either microinjection of 10% biotinylated dextran or implanting small globules of the dried tracer into the motor cortex. While more laborious, microinjection results in better anterograde labelling than implantation of dried biotinylated dextran. A procedure is also described for preparing serial coronal sections through the entire spinal cord and thaw-mounted on a minimum number of slides. The labelled nerve processes in these tissue sections can be visualised in the spinal cord under a fluorescent microscope following incubation with cy3-streptavidin complex. Permanent labelling of the biotinylated nerve processes is achieved by incubation of tissue sections with streptavidin-horseradish peroxidase conjugate followed by stringent washes and staining with tetramethylbenzidine. Use of tetramethylbenzidine allows resolution of a greater number of finer labelled processes than diaminobenzindine and allows clear visualisation of individual regenerating corticospinal tract processes. Using these procedures, we demonstrate that the corticospinal tract is completely lesioned by a standardised contusion spinal cord injury produced by the New York University weight-drop device.

Animals↗
PubMed2000

Macrophage-mediated activation of camptothecin analogue T-2513-carboxymethyl dextran conjugate (T-0128): possible cellular mechanism for antitumor activity.

Camptothecin (CPT) analogue T-2513-carboxymethyl (CM) dextran conjugate (T-0128) suppressed human tumor xenografts that were refractory to CPTs. This improvement was explained by its altered pharmacokinetics, but the cellular mechanism of action is still not clear. For this reason, in the present study we examined the determinants of T-0128 action at the cellular level. In vitro tests showed that T-0128 was inactive, indicating that the requirement for its activity lies in the release of linked T-2513, accompanied by the cellular uptake of the conjugate. The accumulation varied between cell lines: tumor cells, including Walker-256 carcinoma and B16 melanoma, showed only a marginal uptake and an undetectable drug release in the medium. In contrast, macrophage-like cells, such as J774.1, internalized T-0128 very efficiently, and liberated T-2513. With regard to the mode of accumulation, fluid-phase pinocytosis seems to be a key factor based on the followings: a similar cell-specificity existed in the uptake of FITC dextran, a marker of fluid-phase pinocytosis. Also, the macrophage uptake of T-0128 increased almost linearly with its medium concentration and was insensitive to dextran sulfate, a ligand for macrophage scavenger receptor. Comparative efficacy studies of T-0128 in the presence and absence of macrophages demonstrated that macrophages increased the efficacy of T-0128. The enhancement could be explained in terms of increases in the amount of released T-2513. Overall, these results lead us to the conclusion that T-0128 acts like a Trojan horse with the help of macrophages: T-0128 is taken up by macrophages in tumor tissues, and the liberated T-2513 kills tumor cells.

Animals↗
PubMed2002

Release of recombinant human interleukin-2 from dextran-based hydrogels.

In this study, the release of recombinant human interleukin-2 (rhIL-2) from methacrylated dextran (dex-MA) and (lactate-)hydroxyethyl methacrylated dextran (dex-(lactate-)HEMA) hydrogels with varying crosslink density was investigated. Hydrogels derived from dex-MA are stable under physiological conditions (pH 7 and 37 degrees C), whereas dex-HEMA and dex-lactate-HEMA hydrogels degrade due to the presence of hydrolytically sensitive esters in the crosslinks of the gels. The protein release profiles both the non-degradable and degradable dextran-based hydrogels showed that with increasing crosslink density of the gel, the release of rhIL-2 decreases. From dex-MA hydrogels with an initial water content above 70%, the rhIL-2 release followed Fickian diffusion, whereas from gels with an initial water content of 70% or lower the protein was fully entrapped in the hydrogel meshes. In contrast with non-degradable dex-MA hydrogels, degradable dex-lactate-HEMA gels with comparable network characteristics (degree of methacrylate substitution and initial water content) showed an almost zero-order, degradation controlled release of rhIL-2 in a time period of 5-15 days. This paper demonstrates that the release of rhIL-2 from non-degradable dex-MA and degradable dex-lactate-HEMA gels can be modulated by the crosslink density and/or the degradation characteristics of the hydrogel. Importantly, rhIL-2 was mainly released as monomer from the hydrogels and with good retention of its biological activity.

Dextrans↗
PubMed1986

Small-volume infusion of 7.5% NaCl in 6% Dextran 70 for the treatment of severe hemorrhagic shock in swine.

In the initial treatment of the hypovolemic trauma patient, commonly used crystalloids have little clinical benefit in the small volumes generally infused during transport. We evaluated the efficacy of a small-volume infusion of 7.5% NaCl in 6% Dextran 70 as a treatment modality for an otherwise lethal hemorrhage in swine. Sixty chronically instrumented swine were randomized into one of four treatment groups: 0.9% NaCl (NS, n = 15), 7.5% NaCl (HS, n = 15), 6% Dextran 70 (DEX, n = 16), and 7.5% NaCl in 6% Dextran 70 (HSD, n = 14). Each animal was bled 46 mL/kg in 15 minutes. Five minutes after the completion of hemorrhage, the animals were infused with their respective treatment in a volume (11.5 mL/kg) equal to 25% of the shed blood. Of those animals receiving HSD, 100% survived until euthanized at 96 hours. In comparison, animals infused with NS, HS, and DEX had 96-hour survival values of 13%, 53%, and 69%, respectively. The survival rate of the HSD group was significantly better than that of the NS group (P less than .001) and the HS group (P less than .01). The infusion of HSD increased mean arterial pressure, PCO2, and plasma bicarbonate to a significantly greater extent than NS alone (P less than .05). These results demonstrate that a small-volume infusion of the hypertonic sodium chloride/dextran solution is superior to equal volumes of a standard crystalloid in resuscitating animals from hemorrhagic shock.

Animals↗
PubMed1996

Rusty peritoneal dialysis fluid after intravenous administration of iron dextran.

Rusty-colored peritoneal dialysate fluid was observed after intravenous administration of iron dextran to a patient with peritonitis being treated with vancomycin and rifampicin. The discoloration gradually cleared over a 24-hour period. Analysis of the fluid demonstrated that the discoloration could not be explained by the presence of erythrocytes or free hemoglobin. Iron (52 micrograms/dL) was detected in the fluid and decreased to undetectable levels as the discoloration cleared. Addition of iron dextran to an unused bag of peritoneal dialysis fluid to achieve an iron concentration of 52 micrograms/dL resulted in no discoloration. Addition of rifampicin at a clinically relevant serum concentration (10 micrograms/dL) to a different unused bag caused a light orange discoloration. Addition of iron dextran and rifampicin simultaneously in the concentrations mentioned to an unused bag caused a rusty discoloration almost as dark as that observed in our patient. We postulate, therefore, that a combination of iron and rifampicin caused the marked discoloration of our patient's peritoneal effluent.

Ascitic Fluid↗
PubMed1997

The efferent projections of the dorsal and ventral pallidal parts of the pigeon basal ganglia, studied with biotinylated dextran amine.

In the present study we have investigated the efferent projections of both the dorsal and the ventral pallidum of the pigeon basal ganglia, using the sensitive anterograde tracer biotinylated dextran amine [Veenman C. L. et al. (1992) J. Neurosci. Meth. 41, 239-254]. Injections of biotinylated dextran amine in the pigeon dorsal pallidum produced numerous fibers and terminals in specific nuclei of the thalamus, hypothalamus, pretectum and midbrain tegmentum. In the thalamus, labeled fibers and terminals were observed in the avian thalamic reticular nucleus, the proposed motor part of the avian ventral tier (ventrointermediate area), the avian parafascicular nucleus (nucleus dorsointermedius posterior), as well as in the avian nucleus subrotundus (which may be comparable to the posterior intralaminar nuclei of mammals). Labeled fibers and terminals were also observed in the avian subthalamic nucleus (anterior nucleus of the ansa lenticularis), in the pretectum (nucleus spiriformis lateralis) and in the avian substantia nigra pars reticulata. Injections of biotinylated dextran amine in the pigeon ventral pallidum produced fibers and terminals in specific centers of the telencephalon, hypothalamus, thalamus, epithalamus, and midbrain and isthmic tegmentum. Labeled fibers and terminals were also observed in the avian subthalamic nucleus and the inmediately adjacent lateral hypothalamus, the avian thalamic reticular nucleus, the avian medidorsal nucleusaand posterior intralaminar nuclei, and the lateral habenula. Finally, labeled fibers and terminals were found in the ventral tegmental area, the avian substantia nigra pars compacta and the midbrain/isthmic tegmentum, which includes the pedunculopontine tegmental nucleus. Our results indicate that both the dorsal and ventral pallida of birds have unique and specific projection patterns, which are very similar to those of their counterparts in mammals. Our study suggests that these avian basal ganglia regions may be related mainly to somatomotor and limbic functions, respectively.

Anatomy, Artistic↗
PubMed1998

Separation of microsomal cytochrome b5 via phase separation in a mixed solution of Triton X-114 and charged dextran.

The successful introduction of a charged dextran into the Triton X-114 phase separation system for the selective extraction of cytochrome b5 (cyt. b5) in liver microsomes is described. In the absence of charged dextran, 55% of total microsomal proteins and 84% of cyt. b5 were extracted into the surfactant-rich phase. In the presence of anionic dextran sulfate, the extractability of total microsomal proteins was greatly reduced while that of cyt. b5 was increased. After triplicate extraction, cyt. b5 was purified more than 10-fold from microsomes with a recovery of 91% in the surfactant-rich phase. In view of its operational simplicity, this method provides a good means for the partial purification of cyt. b5 prior to chromatographic separations.

Animals↗
PubMed2000

Dextran-methylprednisolone succinate as a prodrug of methylprednisolone: in vitro immunosuppressive effects on rat blood and spleen lymphocytes.

The in vitro immunosuppressive activity of a conjugate of methylprednisolone (MP) with dextran 70 kDa (DEX-MPS) was tested using the lymphocyte proliferation assay after stimulation of lymphocytes with concanavalin A (Con-A). Blood and spleen lymphocytes, isolated from drug-free male Sprague-Dawley rats, were used in the assay. First, the optimum concentration of Con-A for stimulation of lymphocytes was determined. The inhibition of the lymphocyte proliferation was then tested in the presence of 0.25,0.5, 1.0,2.5,5.0,10,20, and 50 nM concentrations (MP equivalent) of DEX-MPS or free MP. The maximum stimulation of lymphocytes with Con-A was observed at mitogen concentrations of 2.5 and 10 microg/ml for the spleen and blood lymphocytes, respectively. For free MP, sigmoidal relationships were observed between the effect (% inhibition of lymphocyte proliferation) and the logarithm of MP concentration. Additionally, the maximum inhibitory effect (I(max)) and MP concentration producing half of I(max) (IC(50)) were, respectively, 98% and 1.38 nM for the blood and 86% and 3.1 nM for the spleen lymphocytes. For MP conjugated to dextran, the response-log concentration curves were substantially shifted to the right with IC(50) values of 40 and 52 nM for the blood and spleen lymphocytes, respectively. It is concluded that compared with free MP, the steroid attached to dextran has minimal immunosuppressive activity. Therefore, to be effective in vivo, DEX-MPS should release MP in the body.

Animals↗