Review of the Clinical Experiences of Feeding Infants Formula Containing the Human Milk Oligosaccharide 2'-Fucosyllactose.

Human milk oligosaccharides (HMOs) are the third most abundant solid component in human milk after lactose and lipids. Preclinical research has demonstrated that HMOs and specifically 2'-fucosyllactose (2'-FL) are more than a prebiotic and have multiple functions, including immune, gut, and cognition benefits. Previously, human milk has been the only source for significant levels of HMOs. The most abundant HMO in most mothers' breast milk is 2'-FL. Recently, 2'-FL has been synthesized and shown to be structurally identical to the 2'-FL found in human milk. 2'-FL HMO is now available in some commercial infant formulas. The purpose of this narrative review was to summarize the clinical experiences of feeding infant formula supplemented with the HMO, 2'-FL. Most of these studies investigated standard intact milk protein-based infant formulas containing 2'-FL, and one evaluated a partially hydrolyzed whey-based formula. Collectively, these clinical experiences demonstrated that 2'-FL being added to infant formula was safe, well-tolerated, and absorbed and excreted with similar efficiency to 2'-FL in human milk. Further, infants that were fed formula with 2'-FL had immune benefits, fewer parent-reported respiratory infections, and improved symptoms of formula intolerance. Ultimately, infant formula with 2'-FL supports immune and gut health and is closer compositionally and functionally to human milk.

A novel synthesis of 6''-[18 F]-fluoromaltotriose as a PET tracer for imaging bacterial infection.

The aim of this study was to develop a positron emission tomography (PET) tracer to visualize and monitor therapeutic response to bacterial infections. In our continued efforts to find maltose based PET tracers that can image bacterial infections, we have designed and prepared 6''-[18 F]fluoromaltotriose as a second generation PET imaging tracer targeting the maltodextrin transporter of bacteria. We have developed methods to synthesize 6''-deoxy-6''-[18 F]fluoro-α-D-glucopyranosyl-(1-4)-O-α-D-glucopyranosyl-(1-4)-O-D-glucopyranose (6''-[18 F]-fluoromaltotriose) as a bacterial infection PET imaging agent. 6''-[18 F]fluoromaltotriose was prepared from precursor, 2'',3'',4''-tri-O-acetyl-6''-O-nosyl-α-D-glucopyranosyl-(1-4)-O-2',3',6'-tri-O-acetyl-α-D-glucopyranosyl-(1-4)-1,2,3,6-tetra-O-acetyl-D-glucopyranose (per-O-acetyl-6''-O-nosyl-maltotriose 4). This method utilizes the reaction between precursor 4 and anhydrous [18 F]KF/Kryptofix 2.2.2 in dimethylformamide (DMF) at 85°C for 10 minutes to yield per-O-acetyl-6''-deoxy-6-'' [18 F]-fluoromaltotriose (7). Successive acidic and basic hydrolysis of the acetyl protecting groups in 7 produced 6''-[18 F]fluoromaltotriose (8). Also, cold 6''- [19 F]fluoromaltotriose was prepared from per-O-acetyl-6''-hydroxymaltotriose via a diethylaminosulfur trifluoride reaction followed by a basic hydrolysis. A successful synthesis of 6''-[18 F]-fluoromaltotriose has been accomplished in 8 ± 1.2% radiochemical yield (decay corrected). Total synthesis time was 120 minutes. Serum stability of 6''-[18 F]fluoromaltotriose at 37°C indicated that 6''-[18 F]-fluoromaltotriose remained intact up to 2 hours. In conclusion, we have successfully synthesized 6''-[18 F]-fluoromaltotriose via direct fluorination of an appropriate precursor of a protected maltotriose.

Major human milk oligosaccharides are absorbed into the systemic circulation after oral administration in rats.

Human milk oligosaccharides (HMO) are involved in many biological functions influencing infant health. Although HMO act locally at the intestine, recent evidence has demonstrated that HMO are partially incorporated into the systemic circulation of breast-fed infants. In the last few years, a large amount of research has been conducted using preclinical models to uncover new biological functions of HMO. The aim of this study was to evaluate the absorption and urine excretion of HMO in rats. We administered a single oral dose of the following HMO: 2'-fucosyllactose (2'-FL), 6'-sialyllactose and lacto-N-neotetraose at different concentrations to adult rats. The time course of absorption of HMO into the bloodstream and their appearance in urine was studied. Our results showed that rats, similar to human infants, are able to effectively absorb a portion of HMO from the intestine into plasma and to excrete them in urine. On the basis of this, we also conducted a specific kinetic absorption study with 2'-FL, the most predominant HMO in human milk, in 9-11-d-old rat pups. Our results confirmed that a significant amount of 2'-FL was absorbed into the systemic circulation and subsequently excreted in urine during lactation in rats in a dose-depended manner. We also found basal levels of these HMO in plasma and urine of adult rats as well as rat pups as a natural result of nursing. Our data suggest that the rat may be a useful preclinical model that provides new insights into the metabolism and functions of HMO.

Effect of a mixture of GOS/FOS® on calcium absorption and retention during recovery from protein malnutrition: experimental model in growing rats.

INTRODUCTION: During growth, protein deprivation impairs epiphyseal growth plate (EGP) height, bone volume (BV) and endochondral ossification. During catch-up growth, Ca availability becomes essential to ensure the extra amount needed to achieve optimal peak bone mass and strength. GOS and FOS improve mineral absorption in the colon. PURPOSE: The effect of a mixture of GOS/FOS® 9:1 added to a 0.5 %Ca (NCa) and a 0.3 %Ca (LCa) diets on Ca, P and Mg absorptions and bone mineralization, density and structure using an experimental model of growing rats recovering from early protein malnutrition was investigated. METHODS: To induce protein malnutrition, rats were fed a low protein diet: 4 % (LPD) during 1 week and then were randomly assigned to recovery groups (R) until day 50 (T = 50) as follows: R0.5 %: NCa; RP0.5 %: NCa + 5.3 % GOS/FOS®; R0.3 %: LCa and RP0.3 %: LCa + 5.3 % GOS/FOS®. Control groups received the 0.5 %Ca or 0.3 %Ca diet from weaning until day 40 or 50. RESULTS: Body weight and length increased in C groups throughout the study; both were arrested in all R during LPD consumption and increased immediately after re-feeding. Independently of dietary Ca content, LS counts, ß-glucosidase and Ca, P and Mg absorption increased, whereas cecum pH, ß-glucuronidase, urease and tryptophanase decreased in RP0.5 %: and RP0.3 %: as compared to the other studied groups (p < 0.01). Prebiotic consumption decreased CTX levels and increased femur Ca, Mg and P contents, total skeleton bone mineral content, proximal tibia and spine BMD, BV, EGP height and hypertrophic zone thickness, stiffness and elastic modulus as compared to recovery groups fed the prebiotic-free diets. CONCLUSION: Under the present experimental conditions, GOS/FOS® mixture induced colonic positive effects, which increased Ca, P and Mg absorption. Thus, consuming the prebiotic-containing diet resulted in an extra amount of minerals that improved bone development in growing rats recovering from protein malnutrition.

Infants Fed a Lower Calorie Formula With 2'FL Show Growth and 2'FL Uptake Like Breast-Fed Infants.

OBJECTIVES: The aim of the present study was to examine the growth and tolerance of infants fed infant formulas with a caloric density closer to human milk (HM) supplemented with human milk oligosaccharides (HMOs) and to study uptake of the HMOs. METHODS: A prospective, randomized, controlled, growth and tolerance study was conducted in healthy, singleton infants (birth weight ≥2490 g), who were enrolled by day of life (DOL) 5. Formula-fed infants were randomized to 1 of 3 formulas with a caloric density of 64.3 kcal/dL. Each formula contained galactooligosaccharides, and the 2 experimental formulas contained varying levels (0.2 and 1.0 g/L) of the HMO 2'-fucosyllactose (2'FL). The 3 formula groups were compared with an HM-fed reference group. Infants were exclusively fed either formula (n = 189) or HM (n = 65) from enrollment to 119 DOL. 2'FL was measured in the blood and urine collected from a subset of infants at DOL 42 and 119, and in HM collected from breast-feeding mothers at DOL 42. RESULTS: There were no significant differences among any groups for weight, length, or head circumference growth during the 4-month study period. All of the formulas were well tolerated and comparable for average stool consistency, number of stools per day, and percent of feedings associated with spitting up or vomit. 2'FL was present in the plasma and urine of infants fed 2'FL, and there were no significant differences in 2'FL uptake relative to the concentration fed. CONCLUSIONS: This is the first report of infants fed 2'FL-fortified formulas with a caloric density similar to HM. Growth and 2'FL uptake were similar to those of HM-fed infants.

Induced fit or conformational selection? The role of the semi-closed state in the maltose binding protein.

A full characterization of the thermodynamic forces underlying ligand-associated conformational changes in proteins is essential for understanding and manipulating diverse biological processes, including transport, signaling, and enzymatic activity. Recent experiments on the maltose binding protein (MBP) have provided valuable data about the different conformational states implicated in the ligand recognition process; however, a complete picture of the accessible pathways and the associated changes in free energy remains elusive. Here we describe results from advanced accelerated molecular dynamics (aMD) simulations, coupled with adaptively biased force (ABF) and thermodynamic integration (TI) free energy methods. The combination of approaches allows us to track the ligand recognition process on the microsecond time scale and provides a detailed characterization of the protein's dynamic and the relative energy of stable states. We find that an induced-fit (IF) mechanism is most likely and that a mechanism involving both a conformational selection (CS) step and an IF step is also possible. The complete recognition process is best viewed as a "Pac Man" type action where the ligand is initially localized to one domain and naturally occurring hinge-bending vibrations in the protein are able to assist the recognition process by increasing the chances of a favorable encounter with side chains on the other domain, leading to a population shift. This interpretation is consistent with experiments and provides new insight into the complex recognition mechanism. The methods employed here are able to describe IF and CS effects and provide formally rigorous means of computing free energy changes. As such, they are superior to conventional MD and flexible docking alone and hold great promise for future development and applications to drug discovery.

Oligosaccharide promotes bioavailability of a water-soluble flavonoid glycoside, alpha G-rutin, in rats.

This study examined the effects of a nondigestible saccharide, difructose anhydride (DFA) III, and fructooligosaccharides (FOS) on the intestinal absorption and metabolism of alpha G-rutin, a quercetin glycoside in rats during a 2 week feeding period with diets containing 1% alpha G-rutin with or without 1.5 or 3% DFAIII and FOS. Blood concentrations and urinary excretion of quercetin derivatives were largely and dose-dependently increased during the test period with feeding DFA III and FOS. The amounts of quercetin derivatives in the cecal contents and feces were also much higher in both saccharide groups than in the control group. The degradation rate of aglycone, estimated by differences between ingestion and sum of fecal and urinary excretion, were suppressed in the both saccharide groups. Cecal fermentation was dose-dependently modified by the oligosaccharides. It was concluded that suppression of degrading quercetin aglycone in the large intestine has a major role for increasing alpha G-rutin bioavailability by DFA III and FOS feedings.

Global transcriptional analysis of Streptococcus mutans sugar transporters using microarrays.

The transport of carbohydrates by Streptococcus mutans is accomplished by the phosphoenolpyruvate-phosphotransferase system (PTS) and ATP-binding cassette (ABC) transporters. To undertake a global transcriptional analysis of all S. mutans sugar transporters simultaneously, we used a whole-genome expression microarray. Global transcription profiles of S. mutans UA159 were determined for several monosaccharides (glucose, fructose, galactose, and mannose), disaccharides (sucrose, lactose, maltose, and trehalose), a beta-glucoside (cellobiose), oligosaccharides (raffinose, stachyose, and maltotriose), and a sugar alcohol (mannitol). The results revealed that PTSs were responsible for transport of monosaccharides, disaccharides, beta-glucosides, and sugar alcohol. Six PTSs were transcribed only if a specific sugar was present in the growth medium; thus, they were regulated at the transcriptional level. These included transporters for fructose, lactose, cellobiose, and trehalose and two transporters for mannitol. Three PTSs were repressed under all conditions tested. Interestingly, five PTSs were always highly expressed regardless of the sugar source used, presumably suggesting their availability for immediate uptake of most common dietary sugars (glucose, fructose, maltose, and sucrose). The ABC transporters were found to be specific for oligosaccharides, raffinose, stachyose, and isomaltosaccharides. Compared to the PTSs, the ABC transporters showed higher transcription under several tested conditions, suggesting that they might be transporting multiple substrates.

Difructose anhydride III promotes absorption of the soluble flavonoid alphaG-rutin in rats.

A highly soluble quercetin glycoside, alphaG-rutin, is a glucose adduct of insoluble rutin. We examined the effects of difructose anhydride III (DFAIII; di-D-fructofuranosyl 1,2':2,3'-dianhydride) on intestinal absorption of alphaG-rutin by rat experiments. alphaG-rutin, rutin, quercetin, and the quercetin conjugate appeared in the portal blood after an intubation of alphaG-rutin (100 micromol), DFAIII effected higher portal concentrations of alphaG-rutin in portal cannulated rats. In ligated jejunal and ileal loops of rats, alphaG-rutin, rutin, quercetin, and the quercetin conjugate appeared in the intestinal mesenteric blood at both 30 and 60 min in both loops; the concentration of alphaG-rutin was 1.5-3 times higher when absorbed in the presence DFAIII. In the isolated mucosae of the jejunum and ileum, mucosal-to-serosal passage of alphaG-rutin increased with the addition of 100 micromol of DFAIII. These results indicate that alphaG-rutin is absorbed as the intact form and that DFAIII stimulates its absorption in the small intestine.

[123I]Mtr-TOCA, a radioiodinated and carbohydrated analogue of octreotide: scintigraphic comparison with [111In]octreotide.

PURPOSE: Scintigraphy with maltotriose-[123I]Tyr3-octreotate ([123I]Mtr-TOCA) is compared with [111In]DTPA-Phe1-octreotide ([111In]OC) to assess the differences in pharmacokinetics and imaging properties as well as to estimate the therapeutic potential of the corresponding [131I]Mtr-TOCA. METHODS: Six patients with somatostatin receptor (sstr)-positive tumours were assessed using a dual-head gamma camera. After injection of 137 +/- 28 MBq [123I]Mtr-TOCA, dynamic data acquisition of the upper abdomen (30 min) was performed followed by whole-body scans at 0.5 h, 1 h, 3 h and 20 h as well as by SPECT imaging (tumour) at 2 h. [111In]OC scintigraphy was performed by acquiring whole-body scans (4 h, 24 h) and SPECT (24 h). Using a region of interest (ROI) method, tissue and tumour bound activity was assessed and dosimetry performed. RESULTS: [123I]Mtr-TOCA shows rapid tumour uptake. Up to 4 h, tumour/organ (tu/org) ratios are stable and generally higher than with [111In]OC. From 3 h to 20 h, tu/org ratios increase for spleen, remain stable for liver and decrease significantly for all other tissues. In contrast, with [111In]OC, tu/org ratios decrease slightly between 4 h and 24 h for liver, spleen and kidney and increase for all other tissues. On [123I]Mtr-TOCA scintigraphy, a total of 27 lesions are detected, whereas 33 lesions are detected on [111In]OC scintigraphy (p=0.50). Effective patient absorbed dose is 1.9 +/- 0.9 mSv per 100 MBq [123I]Mtr-TOCA. CONCLUSION: Compared with [111In]OC, [123I]Mtr-TOCA enables faster imaging of sstr-positive tumours with a lower radiation burden to the patient. [123I]Mtr-TOCA and [111In]OC allow for tumour imaging with almost identical contrast and diagnostic yield. As regards peptide receptor radionuclide therapy, radioiodinated Mtr-TOCA is hampered by limited intratumoural activity retention

In vitro and in vivo effects of soluble, monovalent globotriose on bacterial attachment and colonization.

Epithelial cells lining the urinary tract are rich in globo series glycolipids, structurally defined by a Galalpha1,4Gal motif in the oligosaccharide moiety of this glycolipid family. This Galalpha1,4Gal motif is the attachment target for the P-fimbrial adhesin of uropathogenic Escherichia coli. We investigated the ability of a trisaccharide analog of this core motif, globotriose (Galalpha1,4Galbeta1,4Glc), to interfere with uropathogen attachment and colonization in vitro and in vivo. We assessed the ability of globotriose to inhibit and reverse the binding and agglutination of a P-fimbriated strain of E. coli (JR1) using human erythrocytes and immortalized human colonic epithelial cells as targets. Globotriose (5 mg/ml) completely inhibited and reversed cell agglutination and caused a 10- to 100-fold reduction in JR1 binding to target cells, as determined by flow cytometry. In preparation for an in vivo efficacy study, we investigated the distribution and pharmacokinetics of globotriose in the BALB/c mouse. Globotriose was administered via the tail vein, targeting an instantaneous plasma concentration of 5 mg/ml, and in a different experiment, animals were gavaged at 10 times the intravenous (i.v.) dose. Globotriose was rapidly cleared from plasma (half-life [t1/2], 6 min) and slowly excreted via the kidney (t1/2, 4 h). Urine levels of >5 mg/ml were maintained from 4 to 12 h after the i.v. bolus dose, which resulted in a 1-log reduction in established bladder colonization by JR1. These results suggest that free, soluble globotriose is a feasible alternative therapy for urinary tract infections.

Pharmacokinetics of chitobiose and chitotriose administered intravenously or orally to rats.

Chitooligosaccharides have attracted much attention as new biomedical materials. The biologic availability of each of these chitooligosaccharides, however, has not yet been studied. In the present study, we found that chitobiose and chitotriose appeared in the blood of rats with maximum plasma concentrations at around 1 h after administration when given orally at a dose of 30 mg/kg. However, chitotetraose and chitopentaose did not appear in the blood when given at a dose of 300 mg/kg. Pharmacokinetic analysis of chitobiose and chitotriose after intravenous administration at 100 mg/kg revealed that both sugars were eliminated from the body following a one-compartment model and that the former relative to the latter was higher for both the total body clearance (224+/-43 vs. 155+/-26 ml/h/kg) and the distribution volume (107+/-15 vs. 65+/-9 ml/kg). The absolute oral bioavailability of chitobiose was higher than that of chitotriose at all doses (30, 100, and 300 mg/kg) examined. The first-order absorption rate constants for chitobiose and chitotriose at all doses were less than 1.0 h(-1) and smaller than the elimination rate constants (2.2+/-0.3, 2.7+/-0.1 h(-1), respectively). The absorption was slow, resulting in flip-flop kinetics. This study indicates that among various chitooligosaccharides, only chitobiose and chitotriose can be appreciably absorbed from the gastrointestinal tract.

Absorption and urinary excretion of quercetin, rutin, and alphaG-rutin, a water soluble flavonoid, in rats.

Quercetin, rutin, alphaG-rutin (a water soluble flavonoid), and a mixture of rutin and alphaG-rutin were administered to rats by a single gastric intubation, and their absorption and urinary excretion were examined. The plasma and 24 h urinary levels of aglycons (quercetin and tamarixetin/isorhamnetin) were measured by HPLC after deconjugation with beta-glucuronidase/sulfatase treatment. alphaG-rutin was absorbed more rapidly than quercetin or rutin, and the plasma concentrations of quercetin and tamarixetin/isorhamnetin reached the highest peak level 30 min after dosing. Quercetin, rutin, and the mixture of rutin and alphaG-rutin showed the first peak level 8 h, 8 h, and 30 min after dosing, respectively. The area under the concentration-time curve (AUC) for quercetin in rats administered alphaG-rutin was approximately 4.5- and 2-fold higher than those in rats administered quercetin and rutin, respectively, and was almost the same as that in rats administered a mixture of rutin and alphaG-rutin. The highest 24 h urinary excretion was observed in alphaG-rutin-administered rats. These results suggest that alphaG-rutin is absorbed more efficiently than either quercetin or rutin and that a high plasma concentration can be maintained by supplying rutin and alphaG-rutin in combination.

A therapeutic agent with oriented carbohydrates for treatment of infections by Shiga toxin-producing Escherichia coli O157:H7.

Infection with Shiga toxin (Stx)-producing Escherichia coli O157:H7, which causes diarrhea and hemorrhagic colitis in humans, often results in fatal systemic complications, such as neurological damage and hemolytic-uremic syndrome. Because Stx circulating in the blood is a major causative factor of these complications, the development of a Stx neutralizer that functions in the circulation holds promise as a viable therapy. Here we developed a series of carbosilane dendrimers, in which trisaccharides of globotriaosyl ceramide, a receptor for Stx, were variously oriented at their termini (referred to as SUPER TWIG), and identified a SUPER TWIG with six trisaccharides as a Stx neutralizer functioning in the circulation. This SUPER TWIG specifically bound to Stx with high affinity (K(d) = 1.1 x 10(-6) M) and inhibited the incorporation of the toxin into target cells. Intravenous administration of the SUPER TWIG along with Stx to mice substantially reduced the fatal brain damage and completely suppressed the lethal effect of Stx. Moreover, the SUPER TWIG protected mice from challenge with a fatal dose of E. coli O157:H7, even when administered after the establishment of the infection. The SUPER TWIG neutralized Stx in vivo by a mechanism in which the accumulation and immediate degradation of Stx by phagocytic macrophages present in the reticuloendothelial system were induced. Taken together, our findings indicate that this SUPER TWIG is therapeutic agent against infections by Stx-producing E. coli.

Comparison of radioiodinated TOC, TOCA and Mtr-TOCA: the effect of carbohydration on the pharmacokinetics.

Although somatostatin-based peptide receptor imaging (sst-PRI) and peptide receptor radiotherapy (sst-PRRT) of human endocrine tumours and their metastases has become a valuable method, the experience with radiohalogenated sst-directed peptides has so far been disappointing. To extend the broad spectrum of radiohalogens with suitable radionuclide properties for sst-PRI and PRRT, new strategies in ligand development are required. The major drawbacks to be overcome include fast hepatic uptake, high abdominal background activity and low tumour uptake. Recently we introduced radiolabelled glycated octreotides as a new series of sst-binding radiotracers with excellent physicochemical characteristics. In this study we compared [(125)I]Tyr(3)-octreotide ([(125)I]TOC, ( 1)), [(125)I]Tyr(3)-octreotate ([(125)I]TOCA, ( 2)) and a carbohydrated octreotide derivative, maltotriose-[(125)I]Tyr(3)-octreotate ([(125)I]Mtr-TOCA, ( 3)) to evaluate the effect of single C-terminal oxidation and simultaneous N-terminal carbohydration. The biodistribution was compared in nude mice bearing AR42J tumour xenografts. Compared with ( 1), activity uptake of ( 2) and ( 3) at 1 h was decreased in intestine [36% ( 2), 72% ( 3)], liver [62% ( 2), 79% ( 3)] and kidney [34% ( 2), 41% ( 3)], respectively. Blood clearance was fast for all compounds investigated. Using ( 1) as reference, tumour uptake of ( 2) and ( 3) was 3.8- and 4.3-fold higher at 1 h p.i. At 1 h the tumour-to-blood ratio of ( 3) was 28.2+/-7.3, and the tumour-to-muscle ratio, 147+/-48. Specificity of tumour uptake was demonstrated in AR42J tumour-bearing mice by pretreatment with 0.8 mg TOC/kg 5 min prior to injection of ( 3). In cells transfected with sst1-sst5, the binding profile of I-Mtr-TOCA revealed a very high affinity and selectivity for sst2. In a first scintigraphic [(123)I]Mtr-TOCA study of a patient with a carcinoid of the small intestine with known peritoneal carcinomatosis and a solitary liver metastasis, all tumour tissues, including the liver metastasis, were well defined and clearly visible as soon as 30 min p.i. Based on these encouraging findings we conclude that carbohydration is a powerful strategy for the development of new radiolabelled sst-binding peptides and may represent a general method to improve pharmacokinetics of other peptide radioligands. [(123)I]Mtr-TOCA is a very promising new candidate for sst-directed PRI.

Facilitated substrate transport through membrane proteins.

Substrate transport through the membrane protein maltoporin is facilitated by an affinity site in the channel. The analysis of the ion current fluctuations induced by penetration of the sugar into the channel yields the kinetic constants. Modification of the affinity site by replacing the aromatic residues suggests that nature has optimized the channel protein for maximum affinity at the extracellular side, as well as for an increased off-rate to eject a sugar trapped in the pore towards the periplasmic side.

Intravenous synthetic alphaGal saccharides delay hyperacute rejection following pig-to-baboon heart transplantation.

Several oligosaccharides containing the terminal structure Gal(alpha)1-3Gal (alphaGal) and different side chains were tested in vitro for their ability to block natural anti(alpha)Gal antibodies. A di-and a trisaccharide (di(alpha)Gal and tri(alpha)Gal) were selected. A blood group B baboon, having IgG and IgM natural antipig titers of 1:256 and 1:1024 and a hemolytic titer (to pig red blood cells, RBCs) of 1:8, was chosen to measure pharmacokinetic parameters of the saccharides and to assess the extent of in vivo neutralization of the antibodies. Three grams each of the di(alpha)Gal and the tri(alpha)Gal dissolved in saline were administered by bolus intravenous (i.v.) injection. Blood samples were collected at various times and urine was collected at 8 and 24 h. Plasma and urine concentrations of the alphaGal saccharides were estimated by an ELISA specially developed for this study. A fast distribution phase followed by equilibrium and excretion phases were observed, indicating a T1/2 in the order of 1 h. Fifty-eight per cent of the saccharides were recovered in the urine within 24 h. Determination of antipig antibody binding by FACS analysis and of serum cytotoxicity titers for pig endothelial cells demonstrated that a 70% reduction in binding and cytotoxicity could be achieved with plasma saccharide levels of 300-400 microg/ml. Six months later, a pig heart was transplanted heterotopically into the baboon. A 3-g bolus of the saccharide mixture (1.5 g of each saccharide) was given i.v. before allowing blood reperfusion of the transplanted heart, followed by an i.v. infusion of 1 g/hr for 1 hr and 0.5 g/hr for the 3 succeeding hours. Blood concentrations of the saccharides, CH50, hematology and cytotoxicity for PK15 cells were estimated in blood samples taken at various times. Heart function was observed to be satisfactory for 8 h, but was found to have ceased at 18 h. Myocardial biopsies taken at 3 and 5 h showed congestion only, suggestive of minimal vascular rejection, but by 18 h demonstrated severe vascular rejection. In conclusion, alphaGal saccharide therapy given for a period of 4 h delayed, but did not totally prevent, the development of vascular rejection in the pig-to-baboon heart transplant model. alphaGal saccharide therapy may be one of several useful approaches for the prevention of hyperacute rejection in pig-to-primate organ transplantation.

Effects of beano on the tolerability and pharmacodynamics of acarbose.

Acarbose is an alpha-glucosidase inhibitor approved for the treatment of type 2 diabetes mellitus. Acarbose inhibits carbohydrate digestion, allowing an excessive amount of undigested carbohydrate to reach the colon. Bacterial fermentation of the carbohydrate produces intestinal gas, which can cause flatulence and abdominal pain. Beano, an over-the-counter enzyme preparation (alpha-galactosidase), diminishes intestinal gas production by enhancing the breakdown of certain carbohydrates before they reach the lower intestine. This study was undertaken to investigate whether concomitant administration of Beano and acarbose could reduce the flatulence associated with acarbose and, if so, whether Beano would interfere with the effects of acarbose on postprandial serum glucose concentration. In this randomized, double-masked, placebo-controlled, three-period crossover study, 37 patients with type 2 diabetes mellitus received acarbose 100 mg, acarbose 100 mg plus Beano, or placebo. The study population consisted of 20 males and 17 females who ranged in age from 36 to 72 years (mean, 56 years) and in weight from 62 to 142 kg (mean, 92 kg). Each treatment period consisted of 3 days, during which both acarbose and Beano were given at the beginning of each of three meals. There was a 4-day washout interval between each treatment period. The frequency and severity of flatulence were measured using a score compiled from patient diaries. As an additional measure of intestinal gas production, breath hydrogen concentration was measured on day 3 of each treatment period. Postprandial serum glucose concentration was measured at predetermined times after each morning dose to assess pharmacodynamic activity. Patients who took Beano with acarbose had a significantly lower flatulence score than did those who took acarbose alone (0.79 vs 1.09). Consistent with this finding, breath hydrogen concentration was lower after administration of acarbose plus Beano than with acarbose alone (31.2 ppm vs 50.5 ppm). Beano had variable effects on the ability of acarbose to reduce the postprandial serum glucose concentration. Although postprandial serum glucose levels were higher in patients who received acarbose plus Beano than in those who received acarbose alone, both treatments (with or without Beano) resulted in postprandial serum glucose levels that were significantly lower than those seen with placebo. Therefore, although Beano appeared to diminish the activity of acarbose, postprandial serum glucose concentrations still decreased significantly in patients taking Beano with acarbose. Beano has been shown to alleviate the flatulence accompanying acarbose treatment, but it may also interfere with the glucose-lowering effect of acarbose.

Effect of acarbose and simultaneous antacid therapy on blood glucose.

In a single-centre, placebo-controlled, clinical study, the influence of an antacid containing magnesium hydroxide and aluminium hydroxide (Maalox 70; 10 ml) on the pharmacodynamics of the oral antidiabetic drug acarbose (Glucobay 100, Bay g 5421, CAS 56180; 100 mg) was tested in 24 healthy male volunteers. The drugs were given alone or in combination and were compared with placebo. Volunteers were randomized into four different treatment groups. The daily medication over 4 days was 1 x 1 placebo tablet, or 1 x 1 tablet containing 100 mg acarbose, or 1 x 1 tablet containing 100 mg acarbose plus 10 ml antacid suspension, or 1 x 1 placebo tablet plus 10 ml antacid suspension, interrupted by wash-out phases of 6-10 days between successive treatments. Efficacy was assessed on the basis of postprandial blood glucose and serum insulin levels after administration of 75 g sucrose, and was measured as maximal concentrations and 'area under the curve' (0-4 h). No influence of the antacid on the blood glucose and insulin-lowering effect of acarbose could be detected. Hence, there does not appear to be a significant interaction between acarbose and the antacid tested. Antacids similar to that tested do not need to be classified as a contraindication when used in combination with acarbose.

Fructose transport mechanisms in humans.

BACKGROUND & AIMS: The possible mechanisms of fructose transport are diffusion, a disaccharidase-related transport system, and glucose-facilitated fructose transport. However, these mechanisms in the human small intestine have not been systematically examined. This study was designed to investigate the mechanisms of fructose transport in the human duodenojejunum. METHODS: A triple-lumen tube was fluoroscopically positioned in the duodenojejunum of 7 men. Nine carbohydrate-electrolyte solutions were perfused at the rate of 15 mL/min. Acarbose and lactulose were used to examine the disaccharidase-related transport system and glucose-facilitated fructose transport, respectively. RESULTS: Fructose absorption was greater (P < 0.05) from fructose-glucose (FruGlu) and fructose-glucose-acarbose (FruGluA) solutions than from fructose-mannitol (FruMann) and fructose-mannitol-acarbose (FruMannA) solutions, but there was no difference between FruGlu and FruGluA solutions. A sucrose solution produced greater (P < 0.05) sucrose absorption than a sucrose-acarbose solution. Lactulose absorption (0.016-0.039 mmol.h-1.cm-1) was observed from solutions containing glucose or sucrose. Water absorption was not different among sucrose, FruGlu, and glucose solutions. FruMann solution produced net water secretion. These data suggest that free fructose and glucose transport were not inhibited by acarbose and that the presence of glucose induced lactulose absorption and enhanced fructose absorption. CONCLUSIONS: Fructose is transported transcellularly by facilitated diffusion and paracellularly (based on lactulose transport) via glucose-activated solution drag. In the human small intestine, free fructose and glucose transport does not occur via the disaccharidase system.