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PubMed1990

Dextran deposits in tissues of patients undergoing haemodialysis.

Recently the possible storage of dextran-related material in patients undergoing regular haemodialysis has been suggested. We examined biopsy and autopsy specimens of 32 patients treated with regular haemodialysis for 61 +/- 34 months. All patients received dextran-40 as a plasma expander because of hypotension during haemodialysis. The same study was carried out in a control group of 11 haemodialysed patients who were given other plasma expanders. In the 11 patients who received larger doses of dextran-40 (0.38 g/kg body weight per week) we found particles in the cytoplasm of macrophages in various organs, which proved PAS positive and diastase resistant on light microscopy, and birefringent on polarisation. Electron microscopy revealed a fibrillar structure, but ionic analysis by electronic sampler on scanning electron microscopy excluded the presence of silicon. No intracellular inclusions were observed in the control group, nor in the patients given dextran-40 in doses lower than 0.08 g/kg body weight per week. As we also found a linear relationship between the number of particles and the dextran-40 doses given, we hypothesise that the material demonstrated in the macrophages is a structurally modified dextran.

Cytoplasm↗

PubMed1999

Tc-99m dextran and Tc-99m HIG findings in patients with ulcerative colitis.

PURPOSE: Various radionuclide methods have been studied for the evaluation of the disease activity and extent of ulcerative colitis and other protein-losing enteropathies. Recently, Tc-99m dextran and Tc-99m human immunoglobulin (HIG) have been used to detect inflammation and protein loss into the intestine, but only a few studies have been reported with these agents. MATERIALS AND METHODS: In this study, Tc-99m dextran and Tc-99m HIG were used to evaluate disease activity and extent in patients with ulcerative colitis. These agents were used in 12 patients with active disease and in five patients in remission, and five healthy control participants also were included. RESULTS: Large bowel activity was detected in 11 of the 12 patients with active ulcerative colitis using Tc-99m dextran and in 10 patients using Tc-99m HIG. Fifty-eight bowel segments were found to be active with endoscopy, 39 with Tc-99m dextran, and 31 with Tc-99m HIG. No intestinal activity was detected in the control participants. Grade 1 activity localization in the large bowel was detected in three patients with ulcerative colitis in remission using Tc-99m dextran and in one patient using Tc-99m HIG. CONCLUSION: Tc-99m dextran is more sensitive for detecting disease activity and extent than is Tc-99m HIG.

Adult↗

PubMed1999

Tc-99m dextran: a new and sensitive general purpose scintigraphic agent for diagnosing intestinal inflammation.

PURPOSE: This feasibility study was undertaken to compare the sensitivity of Tc-99m dextran with that of Tc-99m human immunoglobulin G to diagnose ulcerative colitis, and to explore its possible role in disease follow-up. MATERIALS AND METHODS: Twenty-six patients with active disease and six patients in remission underwent serial Tc-99m dextran scanning for as long as 3 hours or more after injection. Eight of the patients with active disease also underwent Tc-99m human immunoglobulin G imaging. RESULTS: Twenty-four of 26 (92%) patients with active ulcerative colitis had a positive result of the Tc-99m dextran study, mainly within 1 hour. In comparison, Tc-99m human immunoglobulin G accumulated abnormally in four of eight (50%) patients and had a relatively poor target localization with high persisting background even after 6 hours. Four of the six patients in remission still had a positive result of the dextran scan, but the abnormal uptake was less than that in the patients with active disease. The disease has recurred already in one of these patients. A patient with pancolitis who was receiving steroid enema therapy had intense uptake of Tc-99m dextran in the ascending colon, probability because it was outside the range of the enema. CONCLUSIONS: Tc-99m dextran is a sensitive and cost-effective agent to diagnose ulcerative colitis, and it may have a role in disease follow-up.

Adult↗

PubMed2000

Observation of corneal epithelial disturbance through soft contact lens using fluorescein dextran.

PURPOSE: To confirm the usefulness of fluorescein dextran as a vital dye for observing corneal epithelial disturbance through a medical-use soft contact lens. METHODS: Ten percent fluorescein isothiocyanate-dextran (FITC-dextran) was used as the staining dye. Patients with corneal epithelial disturbance who were wearing therapeutic soft contact lenses were observed using FITC-dextran. RESULTS: Through the soft contact lens, FITC-dextran enabled corneal disturbance observation similar to that seen with sodium fluorescein. In a case of corneal perforation, as well, positive Seidel's test was confirmed through the soft contact lens using this technique. CONCLUSION: FITC-dextran is considered a useful dye for examining the corneal epithelial condition without contact lens removal.

Adult↗

PubMed1990

Effects of dextran infusion on cardiac output, oxygen delivery, and oxygen utilization in piglets during the first month of life.

We determined the effects of volume infusion on cardiac output, oxygen delivery (Do2), oxygen consumption (Vo2), and oxygen extraction (O2 extr) in piglets at ages 5 to 14 days and 3 to 5 wk. Eighteen piglets were anesthetized, intubated, and mechanically ventilated. Six piglets (5 to 14 days old) and six piglets (3 to 5 wk old) received iv dextran (MW 70,000 daltons; 30 to 40 ml/kg) sufficient to raise mean left atrial pressure (LAP) from approximately 4 to 15 mm Hg over 30 min. Six piglets received 0.9% NaCl at 4 ml/kg.h to maintain LAP constant at 4 mm Hg over a 30-min period. All piglets receiving dextran had increased cardiac output (mean elevation 39 +/- 16 [SD]%; range +19% to +73%; p less than .005). This response was mediated entirely by an elevation in stroke volume, as heart rate did not change significantly. However, all piglets receiving dextran reduced Hgb concentration (10.1 +/- 1.5 to 7.5 +/- 1.4 g/dl, p less than .001), a decrease which completely offset the increase in cardiac output. Consequently, Do2 did not increase after dextran infusion (17.4 +/- 1.8 to 18.4 +/- 2.8 ml/min.kg). Neither Vo2 nor O2 extr changed significantly after dextran. No differences were noted in the response to dextran infusion comparing 5 to 14-day-old piglets with 3 to 5-wk-old piglets. Unlike fetal lambs, newborn piglets are able to elevate cardiac output significantly in response to volume loading. However, if these data can be extrapolated to human infants, volume infusion without concurrent blood transfusion is likely to increase systemic cardiac output but not improve Do2.

Animals↗

PubMed1992

Large volume paracentesis and intravenous dextran to treat tense ascites.

Forty patients with cirrhosis of the liver and tense ascites were randomized to receive either aldactone 400 mg/day and furosemide 80 mg/day (n = 20) or repeated large volume paracentesis (LVP) and infusion of low molecular weight dextran (n = 20). Both treatment groups were similar in clinical and laboratory parameters. Complete mobilization of the ascitic fluid was achieved in all receiving LVP and dextran therapy within 1 week of the treatment, in contrast to the minimal mobilization of the ascitic fluid in patients receiving diuretics even after 2 weeks of therapy. Renal function, the clinical parameters of systemic hemodynamics, serum electrolytes, and hepatic function remained stable in patients receiving LVP and dextran and were similar to those in the diuretic-treated patients. We found no deterioration of these functions in the nonedematous patients treated by LVP and dextran even though the protective effect of edema against LVP was lacking in them. Plasma volume estimation in six nonedematous cirrhotic patients treated by LVP and dextran did not reveal any hypovolemia after complete mobilization of ascites. The frequency of complications and death were similar in the two groups. Dextran infusion is a safe, effective, and low-cost replacement therapy in patients with cirrhotic ascites treated by LVP.

Adult↗

PubMed1999

Vascular permeability increase and plasma volume loss induced by endotoxin was attenuated by hypertonic saline with or without dextran.

Endotoxin given intravenously is known to cause plasma leakage and subsequent loss of circulating plasma volume. Hypertonic saline resuscitation has been successfully applied in hemorrhagic and traumatic shock, but its application for the treatment or prevention of septic or endotoxin shock is less well studied. Our aim was to investigate the effects of endotoxin on plasma leakage in hamsters when administered in two different ways: applied locally to the hamster cheek pouch microcirculation or systemically by i.v. injection. The cheek pouch was studied by intravital microscopy using FITC-labeled dextran as a tracer of plasma leakage. Escherichia coli lipopolysaccharide (LPS) was continuously added into the superfusion buffer of the cheek pouch preparation during 120 min in two control groups (each n = 6) and two further groups (each n = 6) treated with either hypertonic saline (HS) or hypertonic saline and dextran (HSD). Treatment was given as an i.v. injection 0.35 mL NaCl 7.5%/100 g b.w. during 4 min starting 15 min prior to the start of endotoxin application. Endotoxin caused a reversible increase in the number of postcapillary venular leaks with a maximal response at 70 min after start of endotoxin application. The maximal responses were reduced to 36% in the HS-treated and to 37% in the HSD-treated group in comparison to what was seen in the control groups. In the second part of the study endotoxin was given i.v. 0.3 mg/kg to anesthetized hamsters (n = 41) and arterial blood samples were collected at 0, 60, 120, and 180 min after endotoxin injection for measurement of hematocrit and plasma FITC-dextran concentration. Hamsters were divided into seven groups: untreated control group (n = 6); HSC control group given only an i.v. injection of hypertonic saline (n = 6); LPS group given endotoxin 0.3 mg/kg during 1 min (n = 9); HSp group given hypertonic saline (NaCl 7.5%) 10 min prior to i.v. endotoxin (n = 6); HSa group given hypertonic saline 10 min after i.v. endotoxin (n = 6); HSD group given hypertonic saline with dextran 40, 10 min prior to i.v. endotoxin (n = 6); HSD control group given only i.v. hypertonic saline + dextran and no endotoxin (n = 2). Injection of endotoxin caused a significant increase in hematocrit, which was counteracted by hypertonic saline treatment, with or without dextran, probably due to reduced extravasation of plasma in postcapillary venules.

Animals↗

PubMed2002

Dextran-induced pulmonary edema in patients with sudden deafness.

OBJECTIVE: Pulmonary complication in cases of sudden deafness after dextran treatment is rarely reported. This study discusses the management of two cases and reviews the current literature. PATIENTS: Two (1%) of 204 patients with sudden deafness patients had fever, cough, and dyspnea after intravenous dextran infusion. Pulmonary edema was diagnosed after chest radiographic examination. RESULTS: After interruption of dextran, subsequent supportive treatment relieved chest discomfort and fever without any sequelae. The results of chest radiograph and laboratory studies, including hemogram, renal function, and arterial blood oxygen saturation, were normal. CONCLUSIONS: Patients receiving dextran treatment should have their clinical symptoms, renal function, chest radiographs, hemogram, and coagulation profiles monitored. If fever, bleeding, cough, or dyspnea occurs during treatment, dextran must be immediately stopped. Subsequent treatment should focus on dextran clearance to prevent further cascade complications.

Aged↗

PubMed2003

Resuscitation from hemorrhagic shock: experimental model comparing normal saline, dextran, and hypertonic saline solutions.

OBJECTIVE: To compare the effectiveness of normal saline, dextran, hypertonic, and hypertonic-hyperoncotic solutions in hemorrhagic shock. DESIGN: Laboratory investigation. SETTING: University hospital, Emergency Surgery and Intensive Care staff. SUBJECTS: Thirty-two large white female pigs. INTERVENTIONS: Routine care included: anesthesia and sedation (ketamine 10 mg/kg, droperidol 0.25 mg/kg, diazepam 0.7 mg/kg, fentanyl 0.006 mg/kg, 2% enflurane, 20% nitrous oxide, pancuronium bromide 0.13 mg/kg); volume-controlled ventilation (Paco(2) 35-40 torr; 4.7-5.4 kPa); cannulation of right carotid artery and pulmonary artery. Three flow probes (subdiaphragmatic aorta, superior mesenteric artery, right renal artery) and regional venous catheters (superior mesenteric vein, right renal vein) were positioned. Animals were bled to 45 mm Hg for 1 hr and resuscitated with four different fluids and blood to normal aortic blood flow and hemoglobin. MEASUREMENTS AND MAIN RESULTS: Mean arterial pressure and blood flow through abdominal aorta ([OV0312](aor)), mesenteric artery ([OV0312](mes)), and renal artery ([OV0312](ren)) were continuously monitored. Cardiac output, systemic and regional oxygen delivery ([U1E0A]o(2), [U1E0A]o(2mes), [U1E0A]o(2ren)), and consumption ([OV0312]o(2), [OV0312]o(2mes), [OV0312]o(2ren)) were recorded every 30 mins. Baseline [OV0312](aor) was restored with different amounts of fluids in the four groups: normal saline (91.35 +/- 22.18 mL/kg); dextran (16.24 +/- 4.42 mL/kg); hypertonic (13.70 +/- 1.44 mL/kg); and hypertonic-hyperoncotic (9.11 +/- 1.20 mL/kg). The amount of sodium load was less using dextran and hypertonic-hyperoncotic and sodium levels were only transiently increased after hypertonic infusion. Mean arterial pressure and cardiac output were normalized in all groups. Animals resuscitated with normal saline and dextran showed increased pulmonary artery pressures. [U1E0A]o(2) was significantly higher after hypertonic-hyperoncotic infusion, because of reduced hemodilution. Hypertonic and hypertonic-hyperoncotic normalized [OV0312](mes), [U1E0A]o(2mes), [OV0312]o(2mes), [OV0312](ren), and [U1E0A]o(2ren), whereas normal saline and dextran did not achieve this result. At the end of the experiment, hypertonic-hyperoncotic maintained mean arterial pressure, cardiac output, and [U1E0A]o(2) until the end of observation in contrast to normal saline, dextran, and hypertonic. CONCLUSIONS: Resuscitation with a small volume of hypertonic-hyperoncotic solution allows systemic and splanchnic hemodynamic and oxygen transport recovery, without an increase in pulmonary artery pressure. It only transiently increased sodium concentration.

Animals↗

PubMed2004

(99m)Tc-dextran scintigraphy to detect disease activity in patients with rheumatoid arthritis.

AIM: To test the applicability of Tc-dextran joint scintigraphy in the assessment of disease activity in patients with rheumatoid arthritis (RA), and to compare it with the clinical disease activity scores and laboratory parameters. METHODS: Twenty-seven patients with RA were investigated using Tc-dextran joint scintigraphy. The images were evaluated semi-quantitatively and the regional uptakes of the radiopharmaceutical were calculated for the knee, wrist and ankle joints. The clinical and laboratory parameters were collected and fully analysed. An articular Ritchie index (a tender joint score), the number of swollen joints (Sw), the number of tender joints, the morning stiffness (h), the total Ritchie articular index (R), the visual analogue scale (VAS) and the Disease Activity Score (DAS) were determined for all patients. RESULTS: Compared with controls, patients with RA had significantly higher regional Tc-dextran uptake in the knee, wrist and ankle joints (P=0.001). The regional Tc-dextran uptake showed no correlation with the patient's age, gender, duration of disease, number of swollen joints (Sw), number of tender joints, morning stiffness (h), VAS, total Ritchie articular index and DAS, or any laboratory parameters. There was a significant correlation between the regional Tc-dextran uptake for individual joints and the articular Ritchie index of the right and left wrist (r=0.42, P=0.03; r=0.45, P=0.02), right and left knee (r=0.66, P<0.0001; r=0.80, P<0.0001) and right and left ankle (r=0.47, P=0.014; r=0.76, P<0.0001), respectively. CONCLUSIONS: This study demonstrates that Tc-dextran scintigraphy is a sensitive method to detect active joint inflammation and could be useful in the management of patients with RA.

Adult↗

PubMed2001

Adherence of Burkholderia cepacia to respiratory tract epithelial cells and inhibition with dextrans.

Adherence of Burkholderia cepacia to cells of the respiratory tract of patients with cystic fibrosis (CF) appears to be a necessary precondition for colonization and infection. To date, no effective anti-adhesive strategy has been devised for preventing B. cepacia infection in CF patients. It was found in this study that B. cepacia adhered to respiratory epithelial cells both in vitro and in vivo. However, strains with cable-like pili (Cbl) exhibited the typical clump formation on pneumocytes, whereas non-cable piliated strains predominantly showed single-cell adherence. Dextrans (nominally 4000-10000 Da) significantly inhibited adhesion of B. cepacia to A549 pneumocytes. When compared on an equal weight basis, the nominally 10000 Da dextran was most inhibitory. A dose-dependent inhibitory effect (up to 80 mg ml(-1)) was observed for most strains. Dextran exerted less of an anti-adhesive effect on the two Cbl+ strains than on the others which were Cbl-. Dextrans appeared to block the adherence in a non-specific fashion, as shown by the observations that the inhibitory effect was readily reversible and oligosaccharides composed of 2-4 glucose units with the same alpha-1,6 linkage were not inhibitory. The mean molecular masses of dextrans used in this study, as determined by gel filtration and MS, were approximately 10-fold lower than those indicated by the manufacturers. Our data suggest that dextran of nominal molecular mass 4000 Da at a concentration of 40 mg ml(-1) (10 mM according to manufacturer's quoted molecular mass) or more may be useful in patients with CF to prevent colonization and infection with B. cepacia.

Animals↗

PubMed1986

Immunochemical similarity of synthetic alpha-(1----3)-branched D-glucans to dextran B1375.

Anti-dextran B1375 antibodies were raised in rabbits by injecting formalin-killed Leuconostoc mesenteroides strain NRRL B1375, and the anti-dextran serum was used to examine native dextran B1375, and synthetic linear and four alpha-(1----3)-branched alpha-(1----6)-D-glucopyranans for similarities. The antiserum reacted with the homologous dextran B1375 and also with all the synthetic linear and branched glucans. Precipitation and precipitation-inhibition studies indicated that the antiserum contained at least three groups of antibodies with different specificities, the first specific for linear alpha-(1----6)-D-glucopyranan structure, the second specific for alpha-D-glycopyranosyl-(1----3)-branching and the last specific for another, unknown structure present in the dextran B1375 molecule. Two samples of the synthetic branched glucans were shown to be immunochemically the most similar to natural dextran B1375 by inhibition experiments.

Antibodies↗

PubMed2006

Natural killer cell activities of synbiotic Lactobacillus casei ssp. casei in conjunction with dextran.

We have reported previously that Lactobacillus casei ssp. casei, together with specific substrate dextran, exhibited an adjuvant effect of stimulating humoral immune responses against bovine serum albumin (BSA) as a model antigen in BALB/c mice. In the present study, among the Lactobacillus species tested, L. casei ssp. casei with dextran significantly elevated the natural killer (NK) cell activities in spleen mononuclear cells from BALB/c mice in comparison to L. casei ssp. casei alone or other Lactobacillus species with or without dextran. Oral administration of L. casei ssp. casei together with dextran also resulted in a significant increase of NK cell activities in healthy human volunteers. Further, L. casei ssp. casei induced significant production of interleukin (IL)-12 in human peripheral blood mononuclear cells and IL-15 mRNA expression in the human intestinal epithelial cell line Caco-2. L. casei ssp. casei with dextran in food also significantly elevated the survival rate of BALB/c mice bearing Meth-A cells. Taken together, these results demonstrate that dietary synbiotic supplementation which is a combination of the L. casei ssp. casei used as a probiotic together with the dextran, a specific substrate as a prebiotic, efficiently elicits murine and human NK cell activities.

Adult↗

PubMed1991

The influence of T cells on the immunoglobulin repertoire and the affinity maturation of the immune response against dextran B512 in C57BL/6 mice.

A collection of hybridomas from C57BL/6 mice producing antibodies to dextran B512 was analysed and found to reflect the immune response in vivo with regard to immunoglobulin class expression, T cell dependency and antibody affinity. IgM-, IgG-3, and IgG-2b, and IgA-producing hybridomas were found. IgG3-producing hybridomas were obtained from nude mice, indicating T cell independent IgG3 synthesis. All monoclonal antibodies were of kappa light chain. A major anti-dextran idiotype was expressed in many monoclonals. Secondary immune responses to dextran were also suppressed at the hybridoma cell level. However, hybridomas from secondary responses produced antibodies expressing the major idiotype, suggesting that anti-idiotype mediated suppression was not responsible for the reduced secondary response. Most monoclonals belonged to the VHJ558 family, but the IgG3-producing hybridomas showed a preferential use of genes from the VHX24 family. All monoclonals were directed against internal structures of the dextran molecule. The affinity for dextran of the IgG antibodies produced in secondary immune responses was drastically increased, even when the mice were immunized with thymus-independent forms of dextran, indicating that T helper cells need not be involved in affinity maturation of the immune response.

Animals↗

PubMedDate not supplied

A comparison of the effects of salbutamol, etilefrine and dextran during hypotension and low cardiac output states in rabbit.

The effects of salbutamol (25 and 50 micrograms/kg), etilefrine (50 and 200 micrograms/kg) and dextran (8 ml/kg) on cardiovascular function have been studied in the rabbit. The three drugs raised the resting cardiac output (with salbutamol producing delta max 52%, P less than 0.001, n = 5) and right heart filling pressure (RHFP, delta max from dextran 3.5 cmH2O; P less than 0.001, n = 6) and lowered total peripheral resistance (TPR, delta max from salbutamol 46%, P less than 0.001, n = 5). However, TPR rose with the 200 micrograms/kg etilefrine (P less than 0.05, n = 5). Pulse pressure rose with salbutamol (P less than 0.001, n = 6) and etilefrine (P less than 0.05, n = 6). Etilefrine raised resting BP (delta max, P less than 0.001, n = 6); salbutamol lowered resting BP (delta max, P less than 0.001, n = 6) while dextran (n = 6) had little effect on resting BP. The actions of salbutamol are mediated mainly through beta 2-adrenoceptors although the drug also has some minor beta 1-adrenoceptor action. With etilefrine, the increase in cardiac output and the reduction in TPR are mediated through beta-adrenoceptors while the increases in RHFP, blood pressure and TPR are a direct action on the alpha-adrenoceptors. However, during haemorrhage the fall in diastolic pressure produced by salbutamol was considerably reduced while the reduction in mean BP and systolic pressure (which sometimes rose) was abolished. Dextran raised BP during hypotension produced by either sympathectomy or haemorrhage but not during normotension. The reflex recovery in RHFP and the reflex tachycardia were slightly attenuated during lower body negative pressure (LBNP) after salbutamol or dextran. The reflex recovery in blood pressure was complete and the pressure sometimes exceeded the resting level by up to 10 mmHg during LBNP after salbutamol, etilefrine (50 micrograms/kg only) and dextran. The reduced TPR (presumably due to vasodilation) and the increases in cardiac output and RHFP at an adequately maintained blood pressure produced by suitable doses of the three drugs may be useful in the management of circulatory shock and related states.

Albuterol↗

PubMed1974

Inhibition by cromoglycate of histamine release from rat peritoneal mast cells induced by mixtures of dextran, phosphatidyl serine and calcium ions.

1 Dextran releases histamine from rat peritoneal mast cells in the presence but not in the absence of phosphatidyl serine (PS). With PS (10 mug/ml) present the effect of dextran was concentration-dependent in the range of 0.2-6 mg/ml.2 PS releases little histamine on its own but mixed with dextran (6 mg/ml) produces a graded effect in the range of 0.3-10 mug/ml.3 The combination of dextran and PS releases no histamine in a medium containing less than 0.1 mM calcium. As the calcium concentration is increased, release occurs and a maximum is reached at calcium 1 mM; at higher concentrations release falls off sharply.4 Histamine release by the combination of dextran (6 mg/ml), PS (10 mug/ml) and calcium (1.8 mM) is inhibited by cromoglycate in the same range (1-30 muM) that inhibits anaphylactic histamine release from rat peritoneal cells.5 Inhibition by cromoglycate occurred with all dextran concentrations tested (0.2-15 mg/ml) but high concentrations of PS (30 and 100 mug/ml) overcame the effect of cromoglycate (2 and 10 muM). Calcium concentrations above 1 mM augmented inhibition by cromoglycate 2 and 10 muM.

Animals↗

PubMed1991

Effects of dextran sulphate on renal dysfunctions induced by gentamicin as determined by the kidney perfusion technique in rats.

The effect of dextran sulphate on accumulation of gentamicin within the renal cortex and on renal functional changes induced by gentamicin has been investigated using the rat renal perfusion technique. Gentamicin accumulation decreased by the coadministration of dextran sulphate, the degree being proportional to dextran sulphate concentration. The filtered load of gentamicin was unaffected by dextran sulphate. The perfusion of kidney with gentamicin brought about a decrease in the reabsorption of Na+ and an increase in the rate of urine flow with no effect on that of glomerular filtration. The addition of dextran sulphate in the perfusate resulted in the resumption of these levels to those of the control. Dextran sulphate thus apparently interacts with gentamicin in the lumen of proximal tubules to inhibit the reabsorption of gentamicin by proximal tubular cells, and prevents the renal dysfunctions induced by gentamicin.

Animals↗

PubMed1983

Dextran-induced aggregation in a mutant of Streptococcus sobrinus 6715-13.

A mutant of wild-type Streptococcus sobrinus 6715-13 has been isolated which resists aggregation by exogenous dextran. This variant is able to form adherent plaque deposits in vitro when cultured in the presence of sucrose and has dextranase activity. In these respects it is the complement of previously described isolates which are plaque formation defective but aggregation normal. Measurements of the incorporation of glucose from glucosyl-labeled sucrose into glucan by cell-associated glucosyltransferase enzyme activity and the thermal labilities of catalytic and receptor functions, as well as the binding of labeled dextrans to the cells, provide evidence that neither dextranase nor glucosyltransferase is the receptor involved in dextran-induced aggregation. Blockage of such bacterial aggregation by anti-glucosyltransferase or anti-dextranase sera suggests cross-reactivity between the antigenic determinants of proteins which recognize alpha(1-6) glucan linkages. A model is proposed, consistent with these and previous findings, in which enzymatic function precedes dextran receptor activity in emergence from the cell. It is also proposed that dextran receptor components of the multireactive glucosyltransferase enzyme(s) and dextranase(s) are spatially separate from, although functionally and antigenically related to, the receptors on the bacterial surface involved in dextran-induced aggregation.

Agglutination↗