Effects of a new mixture of prebiotics on faecal flora and stools in term infants

A double-blind, randomized, controlled study was performed in 90 full term infants to evaluate dose-related bifidogenic effects of a new synergistic mixture of galacto-oligosaccharides (GOS) and fructo-oligosacharides (FOS). The GOS/FOS mixture showed a dose-dependent stimulatory effect on the intestinal growth of bifidobacteria. Also stool consistency and faecal pH were positively affected.

A human flora-associated rat model of the breast-fed infant gut

OBJECTIVES

Bacterial colonization of the infant gut may have important influences on the development of gastrointestinal, respiratory, and allergic disease. Early diet is a major determinant of the gut microflora. It is very difficult to carry out studies in human infants that can investigate the interaction of diet, flora, and mucosa. In this study we have developed an infant human flora-associated (IHFA) rat model to allow such investigation.

METHODS

Germ-free infant rats were infected with fecal bacteria from exclusively breast-fed infants and were maintained on a modified infant formula for 8 weeks. The fecal and cecal contents were collected and compared with feces of breast-fed infants for bacterial populations, bacterial metabolites, and enzymes and for the ability to inhibit adhesion of pathogenic bacteria to human mucosal cells.

RESULTS

The IHFA cecum and feces were dominated by lactic acid bacteria, Bifidobacterium, and lactobacilli, which were representative of the infant feces. The fecal short-chain fatty acid profile was dominated by acetic and lactic acid in a similar manner to human infant feces. Other bacterial metabolites were similar to those of the human infant. Rat intestinal samples were able to inhibit the adhesion of pathogens to mucosal cells, but to a lesser extent than the human samples.

CONCLUSIONS

This IHFA infant model of the intestinal flora of the breast-fed infant is considered valid for studying the effect of diet on bacterial colonization and metabolism.

Testing of endocrine active substances using an enhanced OECD test guideline 407: Experiences from studies on flutamide and ethinylestradiol

Groups of five male and five female Wistar rats were treated by gavage with 0, 1, 10, and 100 mg/kg body weight (b.w.) flutamide (FLU) or 0.01, 0.05, and 0.2 mg/kg b.w. of ethinylestradiol (EE2) for at least 28 days according to an enhanced Organization for Economic Cooperation and Development (OECD) test guideline (TG) 407 to investigate which of the current and/or additional parameters would detect effects on the endocrine system and to provide data on intralaboratory variability. Two identical studies were performed in parallel on each compound. Common enhancements were determination of thyroid hormones (T3, T4) and thyroid stimulating hormone (TSH), of the stage of the estric cycle to ensure necropsy of females in diestrus, of the number and morphology of epididymal sperm, and of additional organ weights (e.g., male accessory sex organs, MASO) and histopathology of additional organs (e.g., pituitary, vagina). Endocrine-mediated findings consistently observed in these studies were decreased relative weights of MASO at 100 mg/kg FLU and at 0.2 mg/kg EE2, histological changes in pituitary and testes at > or = 10 mg/kg and in MASO, epididymis and adrenals at 100 mg/kg in FLU-treated males, histological changes in the mammary gland at > or = 0.05 mg/kg and in testes, MASO and adrenals at 0.2 mg/kg in EE2-treated males, estrogenization of uterus and vagina (despite necropsy in diestrus) at > or = 0.01 mg/kg EE2, and changes in the ovary at 0.2 mg/kg EE2. Spermatology was insensitive (EE2) or revealed changes only at the maximum tolerated dose (MTD). Determination of T3, T4, and TSH did not contribute to the detection of the endocrine effects (FLU) or provided equivocal results. Doubling the group size to 10 animals by combining the studies run in parallel did not increase the sensitivity of detection of endocrine-mediated effects above the level obtained by histopathological examination of groups of five animals. Only some of the proposed enhancements evaluated were helpful in detecting the endocrine-mediated effects of FLU and EE2. Evaluation of studies according to an enhanced TG 407 on 10 compounds with different endocrine activities will identify the most appropriate enhancements.

Mass spectrometric investigations of human milk oligosaccharides

Human milk oligosaccharides (OS) have been fractionated by gel permeation chromatography (GPC) and analyzed by mass spectrometry (MS). Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF/MS) and electrospray ionization (ESI) ion trap/MS were used. Using a large human milk pool, the MALDI-TOF/MS analysis of high-molecular-mass GPC fractions showed that complex, multiply fucosylated and/or sialylated OS are present over a larger mass range than described previously Acidic oligosaccharides could be detected from low-retention-time GPC fractions with masses up to 4000 Da, which has not been reported before.

Detection of four human milk groups with respect to Lewis-blood-group-dependent oligosaccharides by serologic and chromatographic analysis

Oligosaccharides from human milk samples obtained from individual donors were analyzed using high-pH anion-exchange chromatography. Three patterns of neutral oligosaccharides were detected corresponding to milk groups already described. These oligosaccharide groups correspond to the Lewis blood types Le(a-b+), Le(a+b-), and Le(a-b-). A new carbohydrate pattern was detected in a milk sample from a Le(a-b-) person in which only nonfucosylated oligosaccharides and compounds bearing alpha1,3-linked fucosyl residues were found. This finding led to the hypothesis that there exist 4 different oligosaccharide milk groups that fit well to the genetic basis of the Lewis blood group system.

Supplementation of a bovine milk formula with an oligosaccharide mixture increases counts of faecal bifidobacteria in preterm infants

BACKGROUND

The establishment of a balanced intestinal microflora which may protect against infection is desirable for the preterm infant.

OBJECTIVE

To investigate the effect of a preterm formula milk supplement consisting of oligosaccharides in similar proportions to human milk on the faecal flora and stool characteristics of preterm infants.

STUDY DESIGN

To resemble the effect of human milk, an oligosaccharide mixture consisting of 90% galacto-oligosaccharides and 10% fructo-oligosaccharides was used to supplement a standard preterm formula at a concentration of 10 g/l. This supplemented formula was studied in 15 preterm infants, and the results were compared with those found in 15 infants fed a formula supplemented with maltodextrin as placebo. A group fed fortified mother's milk was investigated as a reference group (n = 12). On four days during a 28 day feeding period (1, 7, 14, and 28), the faecal flora was investigated, and stool characteristics, growth, and possible side effects were recorded.

RESULTS

During the study period, the number of bifidobacteria in the group fed the oligosaccharide supplemented formula increased to the upper range of bifidobacteria counts in the reference group. The difference between the supplemented and non-supplemented groups was highly significant (p = 0.0008). The stool characteristics were also influenced by the supplement: the stool frequency after 28 days was significantly lower in the control group than in the oligosaccharide supplemented group (p = 0.0079) and the reference group (p < 0.0001). Over the study period, the stool consistency in the control group became harder, but remained fairly stable in the other two groups. There was no effect of the different diets on the incidence of side effects (crying, regurgitation, vomiting) or on weight gain or length gain.

CONCLUSION

Supplementing preterm formula with a mixture of galacto- and fructo-oligosaccharides at a concentration of 10 g/l stimulates the growth of bifidobacteria in the intestine and results in stool characteristics similar to those found in preterm infants fed human milk. Therefore prebiotic mixtures such as the one studied may help to improve intestinal tolerance to enteral feeding in preterm infants.

Dosage-related bifidogenic effects of galacto- and fructooligosaccharides in formula-fed term infants

BACKGROUND

Human milk oligosaccharides have been shown to stimulate selectively the growth of Bifidobacteria and Lactobacilli in the intestine. In this study, the bifidogenic effect of an experimental prebiotic oligosaccharide mixture consisting of low-molecular-weight galactooligosaccharides and high-molecular-weight fructooligosaccharides was analyzed in 90 term infants.

METHODS

Two test formulas were supplemented with either 0.4 g/dL or with 0.8 g/dL oligosaccharides. In the control formula, maltodextrin was used as placebo. At study day 1 and study day 28, the fecal species, colony forming units (cfu) and pH were measured and stool characteristics, growth, and side effects were recorded.

RESULTS

At study day 1, the median number of Bifidobacteria did not differ among the groups (0.4 g/dL group, mean [interquartile range] 8.5 [1.9] cfu/g; 0.8 g/dL group, 7.7 [6.1] cfu/g; and the placebo group, 8.8 [6.1] cfu/g) (figures in square brackets are interquartile range). At the end of the 28-day feeding period, the number of Bifidobacteria was significantly increased for both groups receiving supplemented formulas (the 0.4 g/dL group, 9.3 [4.9] cfu/g; the 0.8 g/dL group, 9.7 [0.8] cfu/g) versus the placebo group (7.2 [4.9] cfu/g, P < 0.001). This effect was dose dependent (0.4 g/dL versus 0.8 g/dL, P < 0.01). The number of Lactobacilli also increased significantly in both groups fed the supplemented formulas (versus placebo, P < 0.001), but there was no statistically significant difference between the group fed formula with 0.4 g/dL oligosaccharides and the group fed formula with 0.8 g/dL oligosaccharides. The dosage of supplement significantly influenced the change in fecal pH (P < 0.05) (placebo, pH 5.5-6.1; 0.4 g/dL formula, pH 5.48-5.44; 0.8 g/dL formula, pH 5.54-5.19). Slight changes in the stool frequency resulted in a significant difference between the placebo group and the group fed the 0.8 g/dL formula at day 28 (P < 0.01). Supplementation had a significant dose-dependent influence on stool consistency (0.8 g/dL versus placebo, P < 0.0001; 0.8 g/dL versus 0.4 g/dL, P < 0.01). Supplementation had no influence on the incidence of side effects (crying, regurgitation, vomiting) or growth.

CONCLUSIONS

These data indicate that supplementation of a term infant's formula with a mixture of galacto- and fructooligosaccharides has a dose-dependent stimulating effect on the growth of Bifidobacteria and Lactobacilli in the intestine and results in softer stool with increasing dosage of supplementation.

A trimeric protein complex functions as a synaptic chaperone machine

We identify a chaperone complex composed of (1) the synaptic vesicle cysteine string protein (CSP), thought to function in neurotransmitter release, (2) the ubiquitous heat-shock protein cognate Hsc70, and (3) the SGT protein containing three tandem tetratricopeptide repeats. These three proteins interact with each other to form a stable trimeric complex that is located on the synaptic vesicle surface, and is disrupted in CSP knockout mice. The CSP/SGT/Hsc70 complex functions as an ATP-dependent chaperone that reactivates a denatured substrate. SGT overexpression in cultured neurons inhibits neurotransmitter release, suggesting that the CSP/SGT/Hsc70 complex is important for maintenance of a normal synapse. Taken together, our results identify a novel trimeric complex that functions as a synapse-specific chaperone machine.

Epiretinal membranes after extracapsular cataract surgery

PURPOSE

To determine whether uneventful extracapsular cataract extraction (ECCE) with posterior chamber intraocular lens (PC IOL) implantation induces epiretinal membranes (ERMs).

SETTING

Private practice, with statistical evaluation at a university department in Germany.

METHODS

This prospective study comprised 296 consecutive patients (332 eyes) who had uneventful ECCE with PC IOL implantation for senile cataract. Eyes were examined within 2 weeks preoperatively and 2 weeks and 6, 9, and 12 months postoperatively. The macula was examined with a 78.0 diopter Volk lens. The main outcome measure was the presence of ERM. The membranes were classified as present when cellophane macular reflex (CMR) or macular pucker (MP) was observed.

RESULTS

The median age of the patients was 78 years (range 50 to 97 years). At baseline, ERM was present in 49 of 332 eyes (14.8%), 40 (12.1%) with CMR and 9 (2.7%) with MP. Six months postoperatively, ERM was present in 84 of 332 eyes (25.3%), 72 (21.7%) with CMR and 12 (3.6%) with MP. The difference between the baseline and 6 month incidence was significant (P <.001). All new cases of ERM were of the CMR type. One year after surgery, ERM was present in 54 of 198 eyes (27.3%), 47 (23.7%) with CMR and 7 (3.5%) with MP. The ERMs rarely influenced visual acuity; however, 6 of 12 eyes (50.0%) with MP and 13 of 72 (18.1%) with CMR had metamorphopsia.

CONCLUSIONS

The prevalence of ERM increased by 71.4% during the first 6 months after uneventful ECCE with PC IOL implantation. Thereafter, the prevalence remained about the same. Newly formed ERMs were probably induced by the uneventful surgery. Although new-onset membranes usually do not preclude good visual acuity, they can cause metamorphopsia postoperatively.

The G protein-coupled receptor CL1 interacts directly with proteins of the Shank family

PDZ domains play a pivotal role in the synaptic localization of ion channels, receptors, signaling enzymes, and cell adhesion molecules. These domains mediate protein-protein interactions via the recognition of a conserved sequence motif at the extreme C terminus of their target proteins. By means of a yeast two-hybrid screen using the C terminus of the G protein-coupled alpha-latrotoxin receptor CL1 as bait, three PDZ domain proteins of the Shank family were identified. These proteins belong to a single protein family characterized by a common domain organization. The PDZ domain is highly conserved among the family members, significantly different from other known PDZ domains, and specifically binds to the C terminus of CL1. Shank1 and CL1 are expressed primarily in brain, and both proteins co-enrich in the postsynaptic density. Furthermore, Shank1 induces a clustering of CL1 in transfected cells, strongly supporting an interaction of both proteins in vivo.

Offline coupling of low-pressure anion-exchange chromatography with MALDI-MS to determine the elution order of human milk oligosaccharides

Pooled human milk oligosaccharides were separated into neutral and several acidic oligosaccharide fractions by preparative anion-exchange chromatography (AEC) using AG 1-X2. The oligosaccharides were eluted stepwise using deionized water and three different concentrations of ammonium acetate buffer, pH 6.8. The elution order of the compounds was determined directly by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) analysis of the AEC effluent without any cleanup or concentration steps. Up to a concentration of 500 mM ammonium acetate, the masses of acidic oligosaccharides could be detected by screening the fractions in an automated mode. The combination of the improved chromatographic procedure, the applied MALDI matrices, and operating parameters is suitable for the detection of neutral oligosaccharides as well as acidic oligosaccharides. The method provides high sensitivity and mass accuracy, including for the high-molecular-weight monosialylated oligosaccharides up to 2751.5 Da. The applied ionic strength of the anion-exchange eluents enables a rapid and an unambiguous composition assignment by MALDI-MS for neutral, monosialylated, and disialylated oligosaccharides from human milk. The acidic fractions have to be desalted by electrodialysis and were finally analyzed by HPAEC-PAD to get a high-resolution "fingerprint" of structures present in each fraction. From these analyses, it can be concluded that the isomeric variety of monosialylated oligosaccharides occurring in human milk is higher than estimated before.

Magnetic phase in the near-surface region of an FeBO3 single crystal

An FeBO3 single crystal was studied from 291 K up to the Neel temperature T(N) = 348.35 K by depth selective conversion electron Mossbauer spectroscopy in ultrahigh vacuum (10(-9) mbar). A new magnetic near-surface phase was found. Its thickness D diverges on approaching T(N) and gives a critical exponent for the correlation length of nu = 0.59(4). The phase boundary between the bulk and near-surface phase could be identified.

Human milk oligosaccharides are resistant to enzymatic hydrolysis in the upper gastrointestinal tract

BACKGROUND

Human milk oligosaccharides (HMOs) show a complexity and variety not found in milk of any other species. Although progress has been made in the past 3 decades with regard to identification and structural characterization of HMOs, not much is known about the physiologic functions of HMOs.

OBJECTIVE

As a prerequisite for biological activity in infant metabolism, HMOs have to resist enzymatic hydrolysis in the gastrointestinal tract. To assess the extent to which selected HMOs are hydrolyzed, we carried out in vitro digestion studies using enzyme preparations of human and porcine pancreas and intestinal brush border membranes (BBMs).

DESIGN

Fractions of HMOs, including structurally defined isolated oligosaccharides, were digested for up to 20 h with human pancreatic juice and BBMs prepared from human or porcine intestinal tissue samples. HMOs were incubated by using a porcine pancreatic homogenate and BBMs as enzyme sources. HMOs and digestion products were identified by mass spectrometry and anion-exchange chromatography. Additionally, free D-glucose, L-fucose, and N-acetylneuraminic acid were determined enzymatically.

RESULTS

Whereas maltodextrin (control) was rapidly and completely hydrolyzed, neutral and acidic HMOs showed a profound resistance against pancreatic juice and BBM hydrolases. However, cleavage of most of the HMOs was achieved by using a pancreatic homogenate containing intracellular, including lysosomal, enzymes in addition to secreted enzymes.

CONCLUSIONS

The results of this study strongly suggest that HMOs are not hydrolyzed by enzymes in the upper small intestine. Although intact HMOs may be absorbed, we postulate that a majority of HMOs reach the large intestine, where they serve as substrates for bacterial metabolism. Therefore, HMOs might be considered the soluble fiber fraction of human milk.

Transient opercular syndrome: a manifestation of uncontrolled epileptic activity

Newly appearing oral motor apraxia should alert physicians to the possibility of an organic lesion in the operculum, the perisylvanian cortex. A 6 1/2-year-old boy who is being followed for complex partial seizures with secondary generalization failed to respond to carbamazepine and then to the addition of sodium valproate. The further addition of lamotrigine stopped the seizures but the patient presented with a new onset of opercular syndrome, manifested by severe oral motor apraxia with difficulties in chewing and swallowing and speech. MRI study of the brain revealed no abnormalities. The opercular syndrome resolved completely when the lamotrigine was replaced with phenobarbital, and did not recur during the follow-up period of 2 years. The EEG, however, continued to be abnormal. We conclude that opercular syndrome may be a manifestation of abnormal localized electrical activity at the operculum, even in the absence of an organic lesion on imaging studies, and it may be a marker for an epilepsy which is not easily controlled.

Analysis of high-molecular-weight oligosaccharides from human milk by liquid chromatography and MALDI-MS

Pooled human milk oligosaccharides were fractionated by anion-exchange chromatography on AG 1-X2 and by an improved gel filtration procedure that allowed the separation of large oligosaccharides on Toyopearl HW 40 (S) and Bio-Gel P-6 columns, respectively. The analysis of the resulting nonderivatizated fractions by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) revealed several neutral and acidic high-molecular-weight oligosaccharides. So far unknown acidic oligosaccharides containing up to 20 monomers were detected in a molecular mass range of 2094-3626 Da. Furthermore, neutral structures containing up to 35 monosaccharides were identified after fractionation on Toyopearl HW 40 (S) and subsequent P-6 fractionation, demonstrating the suitability of the applied method for the preparation of oligosaccharides in this high-molecular-mass range. The composition of the detected oligosaccharides was found to be the same as those previously identified in oligosaccharides of lower masses. However, an enormous structural heterogeneity was observed when acidic and neutral fractions were characterized by high-pH anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD). From our analysis we may conclude that each molecular mass identified by MALDI-MS corresponds to a variety of isomeric structures. The total number of oligosaccharides occurring in human milk may consequently be much higher than estimated before.

Two distinct domains in hsc70 are essential for the interaction with the synaptic vesicle cysteine string protein

The cysteine string protein (csp) is a synaptic vesicle protein found to be essential for normal neurotransmitter release. The precise function of csp in the synaptic vesicle cycle is still enigmatic. By interacting with the heat-shock cognate hsc70, a cochaperone-chaperone complex with an unknown function is formed. We report here that the formation of this complex is mediated by two distinct domains in hsc70. The ATPase domain and the substrate-binding domain must cooperate to create a binding site for csp. The C-terminal domain of hsc70 seems to function as a regulator for the formation of the cochaperone-chaperone complex. We also show that the interaction of csp with heat-shock proteins is confined to hsc70 and hsp70. Other heat-shock proteins, like hsp60 and hsp90, do not interact with csp.

Direct interaction of Alzheimer's disease-related presenilin 1 with armadillo protein p0071

Alzheimer's disease-related presenilins are thought to be involved in Notch signaling during embryonic development and/or cellular differentiation. Proteins mediating the cellular functions of the presenilins are still unknown. We utilized the yeast two-hybrid system to identify an interacting armadillo protein, termed p0071, that binds specifically to the hydrophilic loop of presenilin 1. In vivo, the presenilins constitutively undergo proteolytic processing, forming two stable fragments. Here, we show that the C-terminal fragment of presenilin 1 directly binds to p0071. Nine out of 10 armadillo repeats in p0071 are essential for mediating this interaction. Since armadillo proteins, like beta-catenin and APC, are known to participate in cellular signaling, p0071 may function as a mediator of presenilin 1 in signaling events.

Chemical analysis and antimicrobial activity of the resin Ladano, of its essential oil and of the isolated compounds

Fractionation of the resin Ladano from Cistus creticus subsp. creticus and susceptibility testing using the chromatographic fractions showed that its antistaphylococcal activity was mainly due to the diterpene sclareol. The antimicrobial activity of its essential oil, of the chromatographic fractions, and of the isolated compounds was also evaluated against Staphylococcus aureus, Staphylococcus epidermidis, and Staphylococcus hominis.

Matrix optimization for matrix-assisted laser desorption/ionization mass spectrometry of oligosaccharides from human milk

Neutral and acidic oligosaccharides from human milk were analyzed by matrix-assisted laser desorption/ionization mass spectrometry (MALDI/MS). These experiments require suitable matrices; their selection and particularly their preparation protocols must be optimized. Important criteria are sensitivity, reproducibility, tolerance against impurities and resolution over a wide mass range. For analytical investigations of these oligosaccharides, containing labile fucosylated and sialylated components, another property of a matrix becomes a significant factor, namely the influence on ion stability and the extent of (metastable) fragmentation. The experience gained with the MALDI/MS of neutral and acidic oligosaccharides is summarized taking into account different intentions of measurement and typical problems, such as impurities after enzymatic treatment. For a rapid screening of an oligosaccharide sample, superior results were obtained with a new preparation technique using 5-chloro-2-mercaptobenzothiazole (CMBT) as the first layer for 2,5-dihydroxybenzoic acid. For structural analysis by post-source decay, CMBT as the first layer for 3-aminoquinoline is a favoured preparation protocol, because extensive fragmentation is achieved. For acidic oligosaccharides, a special preparation protocol makes it possible to determine the number of sialic acids by inducing highly effective cationization. Matrix-assisted laser desorption/ionization mass spectrometry; matrices; oligosaccharides; post-source decay.

High-sensitivity analysis of neutral underivatized oligosaccharides by nanoelectrospray mass spectrometry

Nanoscale electrospray ionization (nano-ESI) overcomes the sensitivity problems found and reported for neutral oligosaccharides in conventional microscale forced-flow ESI. For a series of compounds ranging from trisaccharides to larger polymers with molecular masses up to 6 kDa, sample concentrations of 10(-5) M, i.e., 10 pmol total sample load, yielded very intense singly or multiply cationized molecule ions in an ion-trap mass spectrometer. In a dilution series, it is exemplified that, at the 10(-8) M level, molecule ion signals can be clearly registered with a S/N ratio of about 7. Only 100 amol of sample has been consumed in this experiment. Investigation of an oligosaccharide-peptide mixture revealed that the oligosaccharide is suppressed in conventional ESI, whereas in nano-ESI both analytes are detected at comparable and high intensities. Mechanistic implications are discussed, emphasizing the influence of surface activity for the two ESI techniques. The very low flow rates inherent to nano-ESI of about 30 nL/min, together with the high signal intensity, make it possible to fully employ the MSn capabilities of an ion-trap mass spectrometer for structural analysis. From less than 1 microL of sample solution it is possible to make consecutive fragmentation experiments up to MS7 to obtain valuable information about the structure of complex oligosaccharides.