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PubMed1976

Dextran degrading bacteria in human oral cavity and their activity against insoluble glucan from Streptococcus mutants.

The distribution of dextran-degrading microorganisms in the saliva and plaque samples from the human oral cavity was assayed on 9 subjects. Approximately 2/3 of the saliva samples degraded Dextran T-150 (Pharmacia, M.W. 150,000) and 1/10 the Blue Dextran (Pharmacia), while 2/5 and 1/8 of the plaque samples degraded Dextran T-150 and Blue Dextran, respectively. Thirty-seven strains of the Blue Dextran degrading bacteria were isolated from the saliva and plaque samples and were classified into 6 groups by their morphology, gram staining and oxygen tolerance. The 24 strains from the 37 isolates, more or less, were shown to degrade the insoluble glucan extracted from Streptococcus mutans FA-1 on the agar plate. The 8 strains, selected from each group, were tested for their activity against the insoluble glucan extracted from Str. mutans (FA-1, HS-6, BHT, CHT, GS-5, LM-7 and PK-1) and Str. salivarius (HHT). The strains belonging to Groups I, II, IV and V showed activity against the insoluble glucan used. Among them, the strains of Group IV (gram negative facultative cocci) and Group V (gram negative strict anaerobic rod) were the most active against the insoluble glucan.

Adult↗

PubMed2001

Aggregation of human RBC in binary dextran-PEG polymer mixtures.

The present study was prompted by prior reports suggesting that small polymers can affect RBC aggregation induced by large macromolecules. Human RBC were washed and re-suspended in isotonic buffer solutions containing 72.5 kDa dextran (DEX 70, 2 g/dl) or 35.0 kDa poly(ethylene glycol) (PEG 35, 0.35 g/dl), then tested for aggregation in these solutions with and without various concentrations of smaller dextrans (10.5 and 18.1 kDa) or PEGs (3.35, 7.5 and 10.0 kDa). RBC aggregation was measured at stasis and at low shear using a photometric cone-plate system (Myrenne Aggregometer) and RBC electrophoretic mobility (EPM) in the various polymer solutions via an automated system (E4, HaSoTec GmbH). Our results indicate: (1) a heterogeneous effect with greater reduction of aggregation for small PEGs added to DEX 70 or for small dextrans added to PEG 35 than for small polymers of the same species; (2) for cells in DEX 70, aggregation decreased with increasing molecular mass and concentration of the small dextrans or PEGs; (3) for cells in PEG 35, small dextrans decreased aggregation with increasing molecular mass and concentration, whereas small PEGs had minimal effects with a minor influence of concentration and an inverse association between molecular mass and inhibition of aggregation. RBC EPM results indicated the expected polymer depletion for cells in DEX 70 or PEG 35, and that small PEGs yielded greater EPM values than small dextrans for cells in PEG 35 whereas the opposite was true for cells in DEX 70. Interpretation of our results in terms of the depletion model for RBC aggregations appears appropriate, and our findings are consistent with the assumption that inhibition of aggregation occurs because of an increase of small molecules in the depletion region. Our results thus suggest the merit of further studies of red blood cell aggregation in binary polymer systems.

Adult↗

PubMedDate not supplied

Effect of dextran molecular weight on protein stabilization during freeze-drying and storage.

The effect of dextran molecular weight on structural stability of freeze-dried products and protein stability in amorphous matrices was investigated during storage at elevated temperatures. Glucose-6-phosphate dehydrogenase (G6PDH) was freeze-dried in 10% (w/v) dextrans of five molecular weights (12 kD, 42 kD, 71 kD, 512 kD and 2000 kD) to residual water content of 0.027 ( 0.004 g/g dry mass. The molecular weight of dextrans affected the glass transition temperature (Tg) of freeze-dried products and the recovery of enzyme activity after freeze-drying. As the molecular weight of dextrans increased from 12 kD to 2000 kD, the Tg increased from 100 degrees C to 120 degrees C, whereas the recovery of protein activity decreased from 85 +/- 4 % to 70 +/- 5%. The inactivation of freeze-dried protein during storage followed a bi-phasic first-order kinetics. The stability of amorphous matrices and protein increased significantly as the molecular weight increased from 12 kD to 512 kD. However, at a higher molecular weight (2000 kD), the stability was reduced. In a separate experiment, the stability of dried dextran/protein samples was studied during heating from 30 degrees C to 99 degrees C at 0.2 degrees C/min and subsequent incubation at 99 degrees C. Dextran with an average molecular weight of 512 kD was again found to provide the best protection. Mechanisms that cause the differences in protein stability among different molecular weight dextrans remain unclear.

Cryopreservation↗

PubMed2002

[Analysis of effect of dextran sulfate on cancer cells].

Peritoneal recurrence is one of the critical problems that occurs after surgery for gastrointestinal cancers. Since no curative treatment has been established for peritoneal recurrence, many efforts have been made to develop an effective method for preventing such recurrence. We focused on dextran sulfate, an anti-cell-adherence agent, to prevent peritoneal metastasis. Our previous studies in vitro and in vivo clarified that dextran sulfate prevents cancer cells from adhering to plastic flasks and the abdominal wall. In this study, we investigated the effects of dextran sulfate on cancer cells from the viewpoint of the cell cycle. Changes in gene expression caused by dextran sulfate were analyzed by cDNA microarrays. Analysis by cDNA microarray revealed the decreased expression of the genes essential to the progression of G1 and S phases. Our results indicate that dextran sulfate suppresses progression of the cell cycle as well as cell adhesion, suggesting that dextran sulfate could be used as an antimetastatic agent. Anti-cell-adherence agents with such mechanisms of action could be effective drugs for treatment during and after operation to prevent peritoneal metastases induced by surgical operation.

Animals↗

PubMed1992

Heparin, dextran and trypan blue allosterically modulate M2 muscarinic receptor binding properties and interfere with receptor-mediated inhibition of adenylate cyclase.

The influences of heparin, dextran and trypan blue on muscarinic receptor binding properties and inhibition of adenylate cyclase were investigated in homogenates of the rat heart. These compounds caused a concentration-dependent enhancement in the specific binding of the muscarinic antagonist [3H]N-methylscopolamine ([3H]NMS) when measured at a radioligand concentration of approximately 0.5 nM in magnesium-containing, low ionic strength buffer. The maximal enhancements of [3H]NMS binding were 2.89-, 1.68- and 1.43-fold increases for heparin, dextran and trypan blue, respectively; the EC50 values for this effect were 0.12, 0.033 and 4.6 microM, respectively. The effects of heparin, dextran and trypan blue on [3H]NMS binding were attributed mainly to an increase in the overall affinity of muscarinic receptors for [3H]NMS, and were greatly attenuated by 100 mM NaCl. These effects were qualitatively similar to those produced by GTP. Heparin, dextran and trypan blue also affected the binding of the muscarinic agonist oxotremorine-M in a manner similar to that of GTP; that is, in the presence of these compounds, agonist affinity was decreased. Our experiments also showed that heparin and dextran attenuate the inhibition of adenylate cyclase activity caused by oxotremorine-M in myocardial homogenates without influencing basal adenylate cyclase activity. We conclude that heparin and dextran interfere with the muscarinic receptor-G protein coupling in the rat heart.

Adenylyl Cyclase Inhibitors↗

PubMed1992

[Prevention of thromboembolism in hip traumatology: low molecular weight heparin versus dextran].

A prospective, randomized trial has been undertaken to evaluate the prophylactic effects of low molecular weight heparin (LMWH) and dextran-70 in 216 patients with hip fracture during a postoperative period of ten days. Deep vein thrombosis (DVT) was diagnosed using the 125Iodine fibrinogen uptake test, confirmed by ascending venography. 113 patients received LMWH and 103 dextran-70. The frequency of DTV of 14.2% in the LMWH group was significantly lower compared with the 30.1% in the dextran group (p less than 0.003). During the first 10 days postoperative there were no fatal pulmonary embolism (PE). After this period PE occurred in 2 patients (1.8%) in the LMWH group and 1 patient (1.0%) in the dextran group. In each group one patient died from PE. There was no major bleeding in either group. The frequency of local complications was slightly higher in the dextran group (10.7%) compared with the LMWH group (3.5%). The postoperative hemoglobin level was significantly lower in dextran treated patients than in patients receiving LMWH (p less than 0.0001).

Adult↗

PubMed1992

Dextran sulfate complexes with potassium phosphate to interfere in determinations of high-density lipoprotein cholesterol.

The interference of dextran sulfate with the colorimetric determination of free cholesterol causes an increase in the absorbance that is proportional to the dextran sulfate concentration in the sample. This makes estimation of the free cholesterol concentration unreliable in high-density lipoprotein-containing supernates obtained after plasma precipitation with dextran sulfate/MgCl2. Analysis of the absorption spectrum demonstrated that the absorbance increase was due to turbidity. We observed this effect with colorimetric reagents based on potassium phosphate buffer but not with those based on sodium phosphate or Tris buffers. This effect is ascribed to dextran sulfate because neither the omission of Mg2+ ions nor their chelation with EDTA prevented turbidity, whereas precipitation of dextran sulfate with Ba2+ counteracted this effect. Therefore, potassium phosphate-buffered reagents appear unsuitable for colorimetric lipid determinations in samples containing dextran sulfate.

Barium↗

PubMed1990

[Erythrocyte elongation with 10% dextran 40,000: comparison of 2 substances].

A dosage-effect-study with two 10% dextrans 40,000 was carried out in 12 venous blood samples of healthy men aged from 21 to 45 years. Dextran A (trade name: Dextran 40,000 "Ebewe") and Dextran B (trade name: "Rheomacrodex") were added in dosages of 0.5 to 10 mg/ml whole blood and the elongation-index of erythrocytes at shearrate 50/sec was determined. From 1 mg up to 10 mg/ml the elongation-index in Dextran B showed a stronger decrease than in Dextran A. Under the highest dosage the difference was about 20%. So it was possible to show that in spite of identical molecular weight there are different effects on deformability of erythrocytes. This should be taken into account for parenteral treatment.

Adult↗

PubMed1990

[Volume replacement with 2 equivalent molecular weight dextrans: effect on erythrocyte elongation in vitro].

The influence of 2 dextranes with the identical molecular weight of 70,000 Dalton for erythrocytes' elongation was investigated in-vitro in 12 healthy male subjects. An increasing dosage between 0.5 and 10 mg/ml Dextran (trade name: Dextran 70 "Ebewe") and Dextran B (weight-equivalent) was added and the elongation index of erythrocytes at shear-rate 50/sec was determined under fluid conditions. Dextran B showed a stronger reduction of elongation index than Dextran A with an elevation of difference up to the highest dosage. The results show that although the molecular weight is identical, differences in hemorheological properties could observed. This should be taken into consideration for volume substitution therapy.

Adult↗

PubMed1991

Abdominal instillation of high-molecular-weight dextran or lactated Ringer's solution after laparoscopic surgery. A randomized comparison of the effect on weight change.

Abdominal fluid retention after the instillation of lactated Ringer's solution into the abdomen after operative laparoscopy was evaluated by comparing the serial weights of patients receiving lactated Ringer's after surgery to those of patients treated with the abdominal instillation of high-molecular-weight dextran and to those of negative controls. Twenty-four patients were randomized to receive either lactated Ringer's or high-molecular-weight dextran after operative laparoscopy. Patients undergoing only diagnostic laparoscopy served as negative controls. Patients receiving either lactated Ringer's or high-molecular-weight dextran had increased weights as compared to the negative controls for at least 36 hours (P less than .5), although the weight gain in the treatment groups did not differ statistically significantly. The weight gain remained significantly greater than in the negative controls on postoperative days 3 and 4 in patients treated with dextran. Since the "flotation" effect of dextran in preventing pelvic adhesions is likely to be most pronounced in the immediate postoperative period, the findings suggest the need for a reinterpretation of adhesion prevention studies in which the use of dextran was compared to that of lactated Ringer's solution or to saline as a negative control.

Dextrans↗

PubMedDate not supplied

Peritoneal fluid kinetics during CAPD measured with intraperitoneal dextran 70.

Simultaneous measurement of transcapillary ultrafiltration (TCUF), lymphatic absorption rate (LAR), and intraperitoneal volume (IPV) was performed by means of intraperitoneally-administered polydisperse dextran 70 in nine CAPD patients during a 4 hr dialysis dwell (glucose 1.36%). The recovery of dextran was 88 +/- 1%. LAR, calculated as the amount of dextran lost, divided by the dialysate dextran concentration, was 1.30 +/- 0.12 ml/min. The time course of TCUF could be described as a hyperbola. Therefore, the application of the Lineweaver-Burke plot made it possible to calculate TCUFmax (median 641 mL) and its half-time (t50: median 211 min). delta IPV4h, calculated as the difference between the Lineweaver-Burke adjusted TCUF4h and LA4h, was correlated with measured delta IPV4h after drainage (r = 0.89, p less than 0.001). The latter was dependent upon LAR (r = -0.71) and effective peritoneal surface area, as represented by mass transfer area coefficients (MTC) of low molecular weight solutes (creatinine r = -0.76, glucose r = -0.81). High MTC values of these solutes were exponentially related to a short t50 (creatinine r = -0.76). LAR was correlated with the MTC of intraperitoneally administered inulin (r = 0.83). Dextran 70 had no measurable effect on solute transport. It is concluded that dextran 70 is a useful marker for the measurement of peritoneal fluid kinetics, even during CAPD with a low glucose concentration in the dialysate.

Adult↗

PubMed1977

Altered growth behavior of virus-transformed cells after treatment with dextran sulfate.

Growth behavior in vitro of 3T3 cells and the cells transformed by polyoma or SV40 virus was studied after their treatment with dextran sulfate. The transformed cells treated with dextran sulfated showed decreased saturation density compared with untreated cells, whereas saturation density of 3T3 cells was hardly affected by treatment with dextran sulfate. The ratio of saturation density of untreated SV3T3 cells to that of the treated cells was 64.1% at 5 microng/ml and was 43.4% at 10 microng/ml of dextran sulfate. In Py3T3 cells the ratio was 45.0% at both concentrations of 10 and 20 microng/ml. Plating efficiency was not affected in 3 cell lines tested after treatment with dextran sulfate. The treated cells showed a tendency to form thin and not piled-up colonies in the central area. The treated SV3T3 and Py3T3 cells were flattened in shape compared with the untreated cells. In agar medium the treated SU 3T3 and Py 3T3 cells showed the tendency to stop growing after forming small colonies, whereas the untreated cells kept growing anf formed large colonies. These results suggested that dextran sulfate altered temporarily the growth of the transformed cells to that of untransformed cells.

Agar↗

PubMed1985

[Inhibition of liver lysosomal cholesterol esterase activity in rats by dextran blue in vivo and in vitro].

Dextran blue decreases the activity of lysosomal acid cholesteryl esterase of rat liver at a concentration from 0.25 M to 10 M without altering acid phosphatase, acid beta-galactosidase and beta-glucosidase activities. The dextran blue filled lysosomes with a high degree of purity prepared by centrifugation over the linear sucrose density gradient contained insignificant impurities (up to 19%) of protein from other organelles. The specific activity of acid phosphatase, beta-galactosidase and beta-glucosidase was increased 35-40-fold in this fraction, whereas the activity of acid cholesteryl esterase rose but 14.7-fold. Chromatography on a Sepharose 2B column of the digitonin-digested native and dextran-containing lysosomes attests to the formation of large dextran aggregates with lysosomal matrix proteins. Since aggregation of dextran blue with acid phosphatase, beta-galactosidase and beta-glucosidase does not affect their activities, it is concluded that to bring about hydrolysis of lipoprotein cholesterol esters, it is necessary that cholesteryl esterase be associated with hydrophobic macromolecules. Moreover, dextran blue can be used for simulation cholesterol esters deposition in lysosomes.

Animals↗

PubMed1985

Effects of dextran on five biuret-based procedures for total protein in serum.

We evaluated the effect of dextran on values for total protein in serum as measured by the biuret method with five widely used automated instruments: the American Monitor Parallel; the Du Pont aca II; the Roche Cobas-Bio; the Kodak Ektachem 400; and the Beckman Astra 8. Dextran concentrations as great as 25 or 30 g/L had relatively little or no influence on total protein measurements by the latter three instruments. Dextran concentrations exceeding 6 g/L caused falsely low results with the aca, whereas the Parallel gave falsely high results when the dextran concentration exceeded 2 g/L. The aca total protein procedure could be protected from the interference by dextran concentrations up to 30 g/L by injecting 0.4-0.8 mL of ethylene glycol directly into the reagent pack before sampling. However, we could not eliminate the interference with the Parallel procedure by any simple means; we thus recommend that it not be used for measuring total protein in serum samples from patients who are being treated with dextran.

Adult↗

PubMed1985

Regulation of the IgM and IgA anti-dextran B1355S response: synergy between IFN-gamma, BCGF II, and IL 2.

T cell help is required for the induction of the humoral antibody response to dextran B1355S, a type II thymus-independent bacterial polysaccharide antigen. In the present study we have identified three B cell growth and differentiation factors that can substitute for T cells in the induction of IgM and IgA antibody responses to alpha(1,3) glucan determinants on dextran B1355S. Dextran B1355S stimulated murine B cell cultures supplemented with a combination of murine recombinant interferon-gamma (IFN-gamma) and a late-acting B cell growth and differentiation factor, BCGF II, produced both IgA and IgM anti-alpha(1,3) dextran plaque-forming cells (PFC). Interleukin 2 (IL 2) was not required for those responses. In contrast, recombinant IFN-gamma and recombinant IL 2 in combination supported the induction of IgA but not IgM anti-alpha(1,3) dextran PFC. In all cases, depletion of surface IgA-bearing B cells significantly decreased IgA but not IgM anti-dextran responses, indicating that the B cells responding to those lymphokines already were committed to IgA expression. These studies indicate that B cell growth and differentiation factors can exhibit differential effects on the induction of IgA compared with IgM responses.

Animals↗

PubMed1985

[The effects of indomethacin and verapamil on dextran-induced shock in rats].

To clarify the mechanism of the anti-shock effect of indomethacin, dextran-induced shock in rats was used as a shock model and compared with the effect of verapamil, a calcium antagonist. Thirty minutes after pretreatment with indomethacin or verapamil, 5% dextran (1 ml/kg body weight) was iv. infused into rats. Pretreatment with indomethacin (5 mg/kg iv.) or verapamil (2 mg/kg iv.) 30 min prior to the dextran infusion prevented significantly a decrease in blood and pulse pressure, and also an increase in the hematocrit value, paw thickness and serum histamine level of rats. Neither pretreatment with indomethacin (or verapamil) nor saline control changed the serum prostaglandin E level before and after the dextran infusion. The effects of verapamil in preventing dextran-induced shock were found to be much greater than those of indomethacin. These results indicated that the shock-preventing effect of indomethacin may be ascribed, at least to some degree, to the role of the drug as a calcium antagonist like verapamil rather than as a cyclooxygenase inhibitor which lowers prostaglandins and/or thromboxane levels. The former effect may be exerted on the mast cells to inhibit calcium influx stimulated by dextran, resulting in the prevention of histamine release.

Animals↗

PubMed1986

The influence of dextran and saline solution upon platelet behavior after microarterial anastomosis.

Microarterial anastomoses were performed on the central arteries of the ears in rabbits. An untreated control group was compared with two groups treated with saline solution and dextran 70 in saline solution respectively. Anastomotic bleeding times were prolonged in both treated groups. In vivo accumulation of 32phosphorous labelled platelets infused prior to any treatment was measured at the anastomotic sites for two hours after anastomosis. Treatment with saline solution resulted in prolonged periods of platelet accumulation--desaggregation processes and abnormally high levels in 50 per cent of the rabbits. Treatment with dextran resulted in increased quantitative accumulation of platelets at all times compared with the control groups. In some rabbits treated with dextran, platelet accumulation patterns indicated microembolization due to increased platelet thrombus fragility. Despite increased platelet accumulation in the dextran groups all vessels showed good patency and only small amounts of thrombosis material compared with the control and saline solution groups. Poor patency was registered only in one instance in the control group and two instances in the saline solution group. Using ex vivo platelet aggregometry, saline solution slightly decreased and dextran slightly increased platelet aggregability. The conclusion is that dextran does not act as an antiplatelet agent but minimizes formation of dangerous solid fibrin platelet thrombi due to a defective fragile fibrin structure adn perhaps increased fibrinolysis.

Animals↗

PubMed1986

Monoclonal anti-alpha (1----3) dextran antibodies of Igha BALB/c and Ighb C.B20 mice display striking similarities.

Allotype Ighb congenic C.B20 mice when immunized with dextran B1355S are unable to produce anti-alpha (1----3) dextran antibodies that express the VH-associated cross-reactive IdX idiotype. This intrastrain-specific idiotype is normally associated only with the anti-dextran response of Igha mice of which BALB/c is a prototype strain. In this study we have obtained monoclonal hybridoma antibodies specific for the alpha (1----3) glucosidic linkage of dextran from C.B20 mice that were presensitized with rabbit anti-IdX antibodies. These antibodies display the light chain isotype distribution, the H chain amino terminal sequence, share VH-associated IdX idiotypic determinants, and finally the similar fine specificity for dextrans observed for anti-alpha (1----3) dextran antibodies of BALB/c mice.

Amino Acid Sequence↗