RESUMEN
The research described here presents data on the effect of galactans of red algae, carrageenans (λ/µ/ν-, κ-, κ/ß-, 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/ß-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.
Asunto(s)
Activación de Complemento/efectos de los fármacos , Galactanos/química , Galactanos/farmacología , Algas Marinas/química , Anticuerpos/sangre , Conformación de Carbohidratos , Secuencia de Carbohidratos , Carragenina/química , Carragenina/farmacología , Vía Alternativa del Complemento/efectos de los fármacos , Vía Clásica del Complemento/efectos de los fármacos , Galactanos/sangre , Humanos , Técnicas In Vitro , Estructura Molecular , Resonancia Magnética Nuclear Biomolecular , Polisacáridos/química , Polisacáridos/farmacología , Rhodophyta/química , Espectroscopía Infrarroja por Transformada de Fourier , Sulfatos/químicaRESUMEN
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 13C-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 13CO2 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.
Asunto(s)
Diabetes Mellitus Tipo 2/sangre , Galactanos/sangre , Galactanos/farmacología , Índice Glucémico/efectos de los fármacos , Mananos/sangre , Mananos/farmacología , Gomas de Plantas/sangre , Gomas de Plantas/farmacología , Periodo Posprandial , Proteína de Suero de Leche/sangre , Proteína de Suero de Leche/farmacología , Anciano , Glucemia/efectos de los fármacos , Femenino , Galactanos/administración & dosificación , Vaciamiento Gástrico/efectos de los fármacos , Humanos , Insulina/sangre , Masculino , Mananos/administración & dosificación , Gomas de Plantas/administración & dosificación , Proteína de Suero de Leche/administración & dosificaciónRESUMEN
SCFA are important end products formed during colonic fermentation of dietary fibre (DF). It has been suggested that propionic and butyric acids affect metabolic parameters, low-grade systemic inflammation, insulin resistance and obesity. The aim of the present study was to investigate whether the various SCFA profiles observed after fermentation in the caecum of rats fed pectin, guar gum and fructo-oligosaccharides (FOS) were also represented in hepatic portal and aortic serum. The SCFA in serum were extracted using hollow fibre-supported liquid membrane extraction before GLC analysis. The concentrations of acetic, propionic and butyric acids in caecal content correlated well with those in portal serum (P< 0·001) for all the three diets. A weaker correlation was found for propionic and butyric acids between the caecal content and aortic serum (P< 0·05). Butyric acid concentration in caecal content was also reflected in the aortic serum (P= 0·019) of rats fed FOS. FOS gave rather low amounts of the SCFA, especially butyric acid, but caecal tissue weight was higher with FOS than with the other two diets. This may be explained by rapid fermentation and quick utilisation/absorption of the SCFA. The present study also showed that propionic acid was metabolised/utilised to a higher extent than butyric acid by colonocytes before reaching the liver. We conclude that the formation of propionic and butyric acids in the caecum is reflected by increased concentrations in the aortic blood. This approach may therefore simplify the evaluation and study of SCFA from DF in human subjects.
Asunto(s)
Aorta/metabolismo , Ácido Butírico/metabolismo , Ciego/metabolismo , Fibras de la Dieta/metabolismo , Hígado/metabolismo , Sistema Porta/metabolismo , Propionatos/metabolismo , Ácido Acético/sangre , Ácido Acético/metabolismo , Animales , Ácido Butírico/sangre , Colon/metabolismo , Dieta , Fermentación , Fructosa/sangre , Fructosa/metabolismo , Galactanos/sangre , Galactanos/metabolismo , Masculino , Mananos/sangre , Mananos/metabolismo , Oligosacáridos/sangre , Oligosacáridos/metabolismo , Pectinas/sangre , Pectinas/metabolismo , Gomas de Plantas/sangre , Gomas de Plantas/metabolismo , Propionatos/sangre , Ratas , Ratas WistarRESUMEN
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-ß was significantly associated with recurrent pregnancy loss. Naive mice infused intravenously with anti-GalNAc-ß developed increased fetal loss. Anti-GalNAc-ß 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-ß Ab is specifically associated with recurrent pregnancy loss both in human patients and experimental mouse model. The pathogenic effects of anti-GalNAc-ß include inhibition of JAR cells invasiveness accompanied by decreased MMP2 and MMP9 secretion.
Asunto(s)
Aborto Espontáneo/inmunología , Síndrome Antifosfolípido/inmunología , Autoanticuerpos/inmunología , Galactanos/inmunología , Aborto Espontáneo/sangre , Aborto Espontáneo/patología , Animales , Síndrome Antifosfolípido/sangre , Síndrome Antifosfolípido/patología , Autoanticuerpos/administración & dosificación , Autoanticuerpos/sangre , Bioensayo , Línea Celular Tumoral , Movimiento Celular/efectos de los fármacos , Movimiento Celular/inmunología , Proliferación Celular/efectos de los fármacos , Coriocarcinoma/inmunología , Coriocarcinoma/metabolismo , Coriocarcinoma/patología , Colágeno , Modelos Animales de Enfermedad , Regulación hacia Abajo , Combinación de Medicamentos , Femenino , Galactanos/sangre , Humanos , Inyecciones Intravenosas , Laminina , Metaloproteinasa 2 de la Matriz/genética , Metaloproteinasa 2 de la Matriz/inmunología , Metaloproteinasa 9 de la Matriz/genética , Metaloproteinasa 9 de la Matriz/inmunología , Ratones , Ratones Endogámicos BALB C , Embarazo , Proteoglicanos , Neoplasias Uterinas/inmunología , Neoplasias Uterinas/metabolismo , Neoplasias Uterinas/patologíaRESUMEN
Despite the importance of protein glycosylation in all physiological and pathological processes and their potential as diagnostic markers and drug targets, the glycome of children is still unexplored. We analyzed N-linked plasma and IgG glycomes in 170 children and adolescents between 6 and 18 years of age. The results showed large biological variability at the population level as well as a large number of associations between different glycans and age. The plasma N-glycome of younger children was found to contain a larger proportion of large complex glycan structures (r = -0.71 for tetrasialylated glycans; r = -0.41 for trisialylated glycans) as well as an increase in disialylated biantennary structures (r = 0.55) with age. Core fucosylation and the level of agalactosylated plasma and IgG glycans decreased while digalactosylated glycans increased with age. This pattern of age-dependent changes in children differs from changes reported in adult population in both, direction and the intensity of changes. Also, sex differences are much smaller in children than in adults and are present mainly during puberty. These important observations should be accounted for when glycan-based diagnostic tests or therapeutics are being developed or evaluated.
Asunto(s)
Glicoproteínas/sangre , Inmunoglobulina G/sangre , Procesamiento Proteico-Postraduccional , Adolescente , Conformación de Carbohidratos , Secuencia de Carbohidratos , Niño , Femenino , Galactanos/sangre , Glicosilación , Hexosaminas/sangre , Humanos , Masculino , Mananos/sangre , Datos de Secuencia Molecular , Ácidos Siálicos/sangreRESUMEN
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.
Asunto(s)
Diltiazem/administración & dosificación , Diltiazem/sangre , Galactanos/administración & dosificación , Galactanos/sangre , Mananos/administración & dosificación , Mananos/sangre , Agua/metabolismo , Administración Oral , Adulto , Animales , Líquidos Corporales/efectos de los fármacos , Líquidos Corporales/metabolismo , Estudios Cruzados , Preparaciones de Acción Retardada/administración & dosificación , Preparaciones de Acción Retardada/metabolismo , Evaluación de Medicamentos/métodos , Humanos , Masculino , Gomas de Plantas , Ratas , Solubilidad/efectos de los fármacos , Comprimidos RecubiertosRESUMEN
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.
Asunto(s)
Galactanos/farmacocinética , Animales , Área Bajo la Curva , Bilis/metabolismo , Separación Celular , Cromatografía en Gel , Cromatografía Líquida de Alta Presión , Relación Dosis-Respuesta a Droga , Heces/química , Fluoresceínas , Colorantes Fluorescentes , Galactanos/sangre , Galactanos/orina , Riñón/metabolismo , Hígado/citología , Hígado/metabolismo , Masculino , Ratas , Ratas Wistar , Receptores de Droga/metabolismo , Distribución TisularRESUMEN
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.
Asunto(s)
Galactanos/análisis , Galactanos/sangre , Radioinmunoensayo/métodos , Animales , Receptor de Asialoglicoproteína , Sitios de Unión de Anticuerpos , Unión Competitiva , Carbohidratos/farmacología , Reacciones Cruzadas , Galactanos/inmunología , Glicoproteínas/inmunología , Sueros Inmunes/inmunología , Lectinas , Lectinas de Plantas , Polisacáridos/inmunología , Conejos , Ratas , Receptores de Superficie Celular , Sensibilidad y Especificidad , ÁrbolesRESUMEN
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.
Asunto(s)
Medios de Contraste/farmacocinética , Galactanos/farmacocinética , Hierro/farmacocinética , Regeneración Hepática/fisiología , Hígado/metabolismo , Óxidos/farmacocinética , Receptores de Superficie Celular/metabolismo , Toxemia/metabolismo , Animales , Receptor de Asialoglicoproteína , Transporte Biológico Activo , Endotoxinas/toxicidad , Galactanos/sangre , Hepatectomía , Hierro/sangre , Cinética , Imagen por Resonancia Magnética , Masculino , Tasa de Depuración Metabólica , Óxidos/sangre , Ratas , Ratas Sprague-DawleyRESUMEN
An experimental reproduction of CBPP was implemented and the animals were surveyed for serology during 4 months. The ELISA/IgG test detects the antibodies few days after the CF test but is more precise for detection on the longer term. The early antibody detection can be done with the ELISA/IgM test. Circulating antigen (galactan) has been detected in a cow that died of an acute form of CBPP. Excretion of mycoplasmas starts 1 to 2 weeks before the seroconversion: the ELISA/IgG test remains positive during the excretion phase and even longer.
Asunto(s)
Anticuerpos Antibacterianos/análisis , Enfermedades de los Bovinos/inmunología , Pleuroneumonía Contagiosa/inmunología , Animales , Bovinos , Enfermedades de los Bovinos/sangre , Pruebas de Fijación del Complemento , Ensayo de Inmunoadsorción Enzimática , Galactanos/sangre , Pleuroneumonía Contagiosa/sangre , Factores de TiempoRESUMEN
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.