Search

The research described here presents data on the effect of galactans of red algae, carrageenans (λ/μ/ν-, κ-, κ/β-, and ι/κ-types), and agar on complement system activation in normal human serum. The experiments were based on well surfaces coated with triggering agents for binding initiating complement components -C3 and C4. The sulfated galactans inhibited C3 binding to lipopolysaccharide with direct dependence on the sulfation degree of polysaccharides. Sulfation degree was also important in carrageenans' capacity to reduce C4 binding to mannan. However, C4 binding to antibodies was considerably activated by carrageenans, especially with 3,6-anhydrogalactose. The gelling carrageenans were able to block antigen binding centers of total serum IgM and with more intensity than non-gelling. No structural characteristics mattered in ameliorating C5 cleavage by plasmin in extrinsic protease complement activation, but λ/μ/ν- and κ/β-carrageenans almost completely inhibited C5 cleavage. Thus, galactans participated in cell surface biology by imitating surface glycans in inhibition of C3 binding and mannose binding lectin, but as to the tthe heclassical pathway these substances stimulated complement, probably due to their structure based on carrabiose., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Background and Aims: Whey protein and guar gum have both been reported to reduce postprandial glycemia in health and type 2 diabetes, associated with stimulation of glucagon-like peptide-1 (GLP-1) and/or slowing of gastric emptying. Our aim was to evaluate, in type 2 diabetes, the acute effects of low dose "preloads" of whey and guar, given alone or in combination before a meal, on postprandial glycemia, insulin, GLP-1, and gastric emptying., Methods: 21 patients with type 2 diabetes, managed by diet or metformin alone, were each studied on 4 days. They received a preload "shake" 15min before a mashed potato meal (368.5 kcal) labeled with 13 C-octanoic-acid. The preloads comprised either (i) 17 g whey (W), (ii) 5 g guar (G), (iii) 17 g whey + 5 g guar (WG) each sweetened with 60 mg sucralose, and (iv) 60 mg sucralose alone (control; C), all dissolved in 150 mL water. Venous blood was sampled frequently for measurements of glucose, insulin, and GLP-1 concentrations. Gastric half-emptying time (T50) was calculated from breath 13 CO 2 excretion over 240 min., Results: Postprandial blood glucose concentrations were lower with W and WG compared to C (each P < 0.0001, treatment × time interaction), and lower after G than C only at 30min. Insulin, GLP-1, and glucagon concentrations were higher after W than WG, G, or C (P < 0.05, treatment × time interaction), without differences between the latter three. Gastric emptying was slower with W (T50: 179.6 ± 6.1 min, P < 0.05) and WG (T50: 197.6 ± 9.7 min, P < 0.0001) when compared to C (T50: 162.9 ± 6.2 min), but did not differ between G (T50: 171.3 ± 7.0) and C (P > 0.99)., Conclusion: Both whey and whey/guar preloads reduced postprandial glycemia, associated with slowing of gastric emptying. Low dose guar was less effective as a preload for glucose-lowering and did not slow gastric emptying., Clinical Trial Registry Number and Website: Australian and New Zealand Clinical Trials Registry, Trial ID ACTRN12615001272583, http://www.anzctr.org.au., (Copyright © 2018 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.)

Objectives: We evaluated the presence of anti-glycan antibodies (aGA) in patients with antiphospholipid syndrome (APS), and associations between aGA and clinical features of the disease., Methods: Sera from APS patients and healthy controls were analyzed for aGA levels by ELISA. Analysis of the association of specific aGA with clinical manifestations of APS was performed. Selected aGA were affinity-purified and injected intravenously into naive mice which were tested for fetal loss. Matrigel invasion assay was performed for detection of choriocarcinoma cells (JAR) invasion and proliferation in the presence of selected aGA. Culture fluid of JAR invasion assays was analyzed for the presence of MMP2 and MMP9., Results: High levels of several aGA were found in APS sera, of which anti-GalNAc-β was significantly associated with recurrent pregnancy loss. Naive mice infused intravenously with anti-GalNAc-β developed increased fetal loss. Anti-GalNAc-β significantly inhibited the in-vitro percentage of JAR invasiveness and the secretion of MMP2 and MMP9 by human JAR cells., Conclusions: APS sera contain significant levels of aGA directed against several glycans. Anti-GalNAc-β Ab is specifically associated with recurrent pregnancy loss both in human patients and experimental mouse model. The pathogenic effects of anti-GalNAc-β include inhibition of JAR cells invasiveness accompanied by decreased MMP2 and MMP9 secretion., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

The objective of the study was to develop guar gum matrix tablets for oral controlled release of water-soluble diltiazem hydrochloride. Matrix tablets of diltiazem hydrochloride, using various viscosity grades of guar gum in 2 proportions, were prepared by wet granulation method and subjected to in vitro drug release studies. Diltiazem hydrochloride matrix tablets containing either 30% wt/wt low-viscosity (LM1), 40% wt/wt medium-viscosity (MM2), or 50% wt/wt high-viscosity (HM2) guar gum showed controlled release. The drug release from all guar gum matrix tablets followed first-order kinetics via Fickian-diffusion. Further, the results of in vitro drug release studies in simulated gastrointestinal and colonic fluids showed that HM2 tablets provided controlled release comparable with marketed sustained release diltiazem hydrochloride tablets (D-SR tablets). Guar gum matrix tablets HM2 showed no change in physical appearance, drug content, or in dissolution pattern after storage at 40 degrees C/relative humidity 75% for 6 months. When subjected to in vivo pharmacokinetic evaluation in healthy volunteers, the HM2 tablets provided a slow and prolonged drug release when compared with D-SR tablets. Based on the results of in vitro and in vivo studies it was concluded that that guar gum matrix tablets provided oral controlled release of water-soluble diltiazem hydrochloride.

Fluorescein-labeled arabinogalactan (FA) was prepared by the reaction with FITC in methyl sulphoxide according to the method of deBelder and Granath. A systemic kinetic analysis of FA in rats was carried out by using a specific high-performance size-exclusion chromatography. Intravenously administered FA was rapidly eliminated from the blood circulation followed by an appreciable distribution to the liver and kidney. FA was accumulated in these organs over a long period whereas negligible levels of FA were detected in the other organs. A marked dose-dependency was seen in the hepatic uptake of FA which was markedly reduced by coinjected asialofetuin whereas the renal uptake of FA was not altered. Measurement of the hepatocellular localization demonstrated the overwhelming distribution of FA in the parenchymal liver cell fraction. Furthermore, the microscopic examination revealed FA that was effectively endocytosed by the parenchymal liver cells. These results suggested that FA which is bound to the asialoglycoprotein receptor with a high affinity is subsequently internalized to the hepatocyte via receptor-mediated endocytosis. FA was partially activated by periodate oxidation in order to acquire aldehyde groups to which guest molecules can be bound. A 12.5% oxidized arabinogalactan keeping a hepatocellular targetability showed a good conjugating reactivity to guest molecules via Schiff-base formation or by reductive amination. It was suggested that arabinogalactan can serve as a potential carrier for the delivery of enzymes and drugs to the parenchymal liver cells via the asialoglycoprotein receptor.

We describe a sensitive and convenient immunoassay for larch arabinogalactan and demonstrate its specificity for larch arabinogalactan. Anti-larch arabinogalactan antiserum is about 10(4) and 10(6) times more selective for detecting larch arabinogalactan than antiserum binds to branch terminal disaccharides consisting of the terminal beta-D-galactosyl residue and the penultimate branch (1-->6)-beta-D-galactosyl residue. It does not bind L-arabinose. The sensitivity of the assay for larch arabinogalactan is less than 0.1 microgram/mL. The application of the assay for measuring arabinogalactan pharmacokinetics in rat blood is illustrated.

The hepatic asialoglycoprotein receptor is responsible for rapid clearance of desiaylated glycoproteins from the circulation by receptor-mediated endocytosis. Previous in vitro studies in hepatocyte preparations from rats subjected to partial hepatectomy (PH) of 70% to stimulate hepatic regeneration showed decreased asialoglycoprotein (ASGP) receptor binding. We used an ASGP receptor-targeted hepatic magnetic resonance imaging (MRI) agent, BMS 180550, to demonstrate similar changes in receptor biology in vivo. BMS 180550 is an arabinogalactan-coated ultrasmall superparamagnetic iron oxide preparation. Arabinogalactan is a ligand for the ASGP receptor and, thereby, targets the contrast agent exclusively to hepatocytes. Hepatic uptake of BMS 180550 was assessed by sequential precontrast and post-contrast MRI in rats subjected to PH of 70%. In regenerating liver 1 and 3 days after PH, the maximum decrease in hepatic signal intensity (62.2% +/- 6.1 and 59.4% +/- 3.8, respectively) was significantly less than the maximum decrease seen in sham-operated animals at 1 and 3 days postsurgery (39.5% +/- 2.5 and 44% +/- 1.0, respectively). The time necessary to reach 80% of the maximum decrease in hepatic signal intensity, (t80), was less than 2 minutes in control rats and increased to 7.5 +/- 1.3 min and 11.0 +/- 2.3 minutes at 1 and 3 days post-PH, respectively. By 7 days post-PH, contrast-enhanced MRI no longer detected a difference in regenerating liver. Because BMS 180550 is taken up exclusively by the liver, clearance of the agent from the blood was used as a measure of hepatic clearance. Concentration-time curves constructed by measuring changes in blood T2 after an intravenous dose of BMS 180550 were used to determine clearance of the agent. Blood clearance of BMS 180550 in normal liver (15.4 +/- 1.08 mL/min) obeyed first-order kinetics and did not vary over the dose range tested (10 to 100 micromol/L/kg iron). One, 3, 7, and 14 days post-PH, clearance varied with dose, suggesting ASGP receptor saturation. As regeneration proceeded, the dose of contrast agent needed to cause a deviation from first-order kinetics increased, suggesting gradual recovery of ASGP receptor function. Hepatic relaxation was determined by in vitro spectroscopy 60 minutes after administration of graded doses of BMS 180550 and showed dose-dependent increases in relaxation. Kinetic analysis at 1 day post-PH demonstrated a decrease in the apparent k(m) and the maximum response, R(max), suggesting a decrease in the number of functional asialoglycoprotein receptors with concomitant increase in receptor affinity. Systemic endotoxemia, which normally accompanies hepatic regeneration induced by PH, also decreased clearance of BMS 180550 and slowed hepatic uptake of the contrast agent. Altered BMS 180550 pharmacokinetics in endotoxin-treated rats was enhanced by prior administration of small doses of competing ligand. Our studies document the value of BMS 180550 in following changes in ASGP function that accompany PH or systemic endotoxemia. This agent may be useful in assessing the degree of hepatic regeneration in patients with clinical liver disease.

The effect of guar gum on glucose and lipid metabolism and on body insulin sensitivity was examined in nine type 1 diabetic patients treated with continuous subcutaneous insulin infusion. The study was done in a randomized, double-blind, crossover fashion with either guar gum or a placebo added to the usual diet four times per day for 4 wk each. Blood glucose levels after breakfast and lunch and daily insulin requirements were significantly lower during the guar-gum than the placebo diet. After a 4-wk guar-gum supplementation, blood glucose response to a test meal was significantly reduced by guar gum compared with the placebo. Hemoglobin A1 (HbA1) and insulin sensitivity remained unchanged. Serum total cholesterol fell by 21% (p less than 0.025). Thus, guar gum can reduce postprandial blood glucose, insulin requirements, and serum total cholesterol levels in type 1 diabetic patients.