Glycemic response to low sugar apple juice treated with invertase, glucose oxidase and catalase.

BACKGROUND/OBJECTIVES: Investigating the effect on post-prandial glycemic and venous serum insulin response of an apple drink following the conversion of its glucose to gluconate. SUBJECTS/METHODS: In a double-blind randomized placebo-controlled clinical trial with cross-over design, 30 male adults with impaired fasting glucose (IFG) received a drink of 500 ml: 1. Verum: Apple juice treated with invertase, glucose oxidase/catalase (glucose 0.05 g; gluconate 18.2 g); 2. CONTROL: Untreated apple juice (free glucose 8.5 g; bound glucose 6.7 g; gluconate below detection limit). Postprandial fingerprick capillary blood glucose and venous serum insulin were measured twice at baseline and at times 0 (start of drink), 15, 30, 45, 60, 90 and 120 min. Gastrointestinal symptoms, stool consistency and satiety were also assessed. RESULTS: The incremental area under the curve (iAUC120) of glucose levels (primary parameter) was significantly lower after verum (mean ± SD: 63.6 ± 46.7 min × mmol/l) compared to control (mean ± SD: 198 ± 80.9 min × mmol/l) (ANOVA F = 137.4, p < 0.001; α = 0.05). Also, iAUC120 of venous serum insulin levels (secondary parameter) was significantly lower after verum (mean ± SD: 2045 ± 991 min × mmol/l) compared to control (3864.3 ± 1941 min × mmol/l), (ANOVA F = 52.94, p < 0.001; α = 0.025). Further parameters of glucose metabolism and ISI = 2/[AUC venous serum insulin × AUC glucose +1] were also improved after verum compared to control. Verum increased stool frequency and decreased stool consistency, as assessed by Bristol stool form scale. CONCLUSIONS: By enzymatic treatment of apple juice its sugar content could be reduced by 21% and postprandial glycemic and venous serum insulin response by 68 and 47%, respectively resulting in a reduction of glycemic load by 74.6% without any adverse gastrointestinal side-effects.

Impact of oral administration of four Lactobacillus strains on Nugent score - systematic review and meta-analysis.

We aimed at assessing the evidence for an effect on vaginal dysbiosis by oral administration of a mixture of Lactobacillus strains isolated from vaginal microbiota. For this purpose, we systematically reviewed the literature for randomised clinical trials (RCTs) in which the effect of oral administration of a mixture of four Lactobacillus strains (Lactobacillus crispatus LbV 88 (DSM 22566), Lactobacillus gasseri LbV 150N (DSM 22583), Lactobacillus jensenii LbV 116 (DSM 22567) and Lactobacillus rhamnosus LbV96 (DSM 22560)) on vaginal dysbiosis was examined based on Nugent score. Four RCTs were identified: a double-blind (DB)-RCT in 60 male-to-female transsexual women with neovagina; an open label RCT in 60 pregnant women with herpes virus infection; a DB-RCT in 36 women with bacterial vaginosis; a DB-RCT in 22 postmenopausal breast cancer patients receiving chemotherapy. Only in the three DB-RCTs Nugent score was assessed. The meta-analysis of these trials showed a significant reduction of Nugent score by probiotics compared to placebo in the fixed (standardised mean differences (SMD) -0.561; confidence interval (CI) -0.935 to -0.186; P=0.004 and random effect models (SMD -0.561; CI -0.935 to -0.186; P=0.004). The odds ratio (OR) of the cases presenting with improved Nugent score after probiotics compared to placebo treatment showed a significant effect in the fixed (OR=3.936; CI 1.702 to 9.100; P=0.001) and random effect model (OR=3.902; CI 1.681 to 9.059; P=0.001) Cochran's Q and I2 statistics showed no heterogeneity. This meta-analysis indicates that the oral intake of the pertinent Lactobacillus strains improves the microbial pattern in vaginal dysbiosis.

Calcium isotope ratios in blood and urine: A new biomarker for the diagnosis of osteoporosis.

We assessed the potential of Calcium (Ca) isotope fractionation measurements in blood (δ44/42CaBlood) and urine (δ44/42CaUrine) as a new biomarker for the diagnosis of osteoporosis. One hundred post-menopausal women aged 50 to 75 years underwent dual-energy X-ray absorptiometry (DXA), the gold standard for determination of bone mineral density. After exclusion of women with kidney failure and vitamin D deficiency (<25 nmol/l) 80 women remained in the study. Of these women 14 fulfilled the standard diagnostic criteria for osteoporosis based on DXA. Both the δ44/42CaBlood (p < 0.001) and δ44/42CaUrine (p = 0.004) values were significantly different in women with osteoporosis (δ44/42CaBlood: -0.99 ±â€¯0.10‰, δ 44/42CaUrine: +0.10 ±â€¯0.21‰, (Mean ±â€¯one standard deviation (SD), n = 14)) from those without osteoporosis (δ44/42CaBlood: -0.84 ±â€¯0.14‰, δ44/42CaUrine: +0.35 ±â€¯0.33‰, (SD), n = 66). This corresponded to the average Ca concentrations in morning spot urine samples ([Ca]Urine) which were higher (p = 0.041) in those women suffering from osteoporosis ([Ca]Urine-Osteoporosis: 2.58 ±â€¯1.26 mmol/l, (SD), n = 14) than in the control group ([Ca]Urine-Control: 1.96 ±â€¯1.39 mmol/l, (SD), n = 66). However, blood Ca concentrations ([Ca]Blood) were statistically indistinguishable between groups ([Ca]Blood, control: 2.39 ±â€¯0.10 mmol/l (SD), n = 66); osteoporosis group: 2.43 ±â€¯0.10 mmol/l (SD, n = 14) and were also not correlated to their corresponding Ca isotope compositions. The δ44/42CaBlood and δ44/42CaUrine values correlated significantly (p = 0.004 to p = 0.031) with their corresponding DXA data indicating that both Ca isotope ratios are biomarkers for osteoporosis. Furthermore, Ca isotope ratios were significantly correlated to other clinical parameters ([Ca]Urine, ([Ca]Urine/Creatinine)) and biomarkers (CRP, CTX/P1NP) associated with bone mineralization and demineralization. From regression analysis it can be shown that the δ44/42CaBlood values are the best biomarker for osteoporosis and that no other clinical parameters need to be taken into account in order to improve diagnosis. Cut-off values for discrimination of subjects suffering from osteoporosis were - 0.85‰ and 0.16‰ for δ44/42CaBlood and δ44/42CaUrine, respectively. Corresponding sensitivities were 100% for δ44/42CaBlood and ~79% for δ44/42CaUrine. Apparent specificities were ~55% for δ44/42CaBlood and ~71%. The apparent discrepancy in the number of diagnosed cases is reconciled by the different methodological approaches to diagnose osteoporosis. DXA reflects the bone mass density (BMD) of selected bones only (femur and spine) whereas the Ca isotope biomarker reflects bone Ca loss of the whole skeleton. In addition, the close correlation between Ca isotopes and biomarkers of bone demineralization suggest that early changes in bone demineralization are detected by Ca isotope values, long before radiological changes in BMD can manifest on DXA. Further studies are required to independently confirm that Ca isotope measurement provide a sensitive, non-invasive and radiation-free method for the diagnosis of osteoporosis.

Effect of a yoghurt drink containing Lactobacillus strains on bacterial vaginosis in women - a double-blind, randomised, controlled clinical pilot trial.

Bacterial vaginosis (BV) is characterised by a depletion of lactobacilli in favour of an overgrowth of anaerobic bacteria. It is associated with increased risk for urogenital infections and abortion. In this study we assessed the effect of a yoghurt drink containing Lactobacillus strains on BV. The strains had been isolated from healthy pregnant women and selected for acidification capacity, production of H2O2, glycogen utilisation, bile salt tolerance and inhibition of pathogens. Using Amsel criteria BV was diagnosed in 36 women aged ≥18 years with stable menstrual cycle or menopause. They were treated with oral metronidazole for 7 days (2×500 mg/d). Starting with the treatment, women consumed twice daily either verum or placebo during 4 weeks. Verum was 125 g yoghurt containing (besides Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus thermophilus) living strains Lactobacillus crispatus LbV 88 (DSM 22566), Lactobacillus gasseri LbV 150N (DSM 22583), Lactobacillus jensenii LbV 116 (DSM 22567) and Lactobacillus rhamnosus LbV96 (DSM 22560), each 1×107 cfu/ml; placebo was 125 g chemically acidified milk. After 4 weeks of intervention 0 of 17 had BV in the verum group versus 6 of 17 in the s.a. control (0.018 in Fisher Exact test). Amsel score decreased during the intervention period by 4.0 (median) (4.0; 3.0) (25th; 75th percentile) in the verum group compared to 2.0 (4.0; 0.0) in the control group (P=0.038 in Mann-Whitney test). Discharge and odour (Amsel criteria 2+3) also decreased by 2.0 (2.0; 1.0) in the verum compared to 1.0 (2.0; 0.0) in the control group (P=0.01) and differed after 4 weeks intervention between the groups 0.0 (0.0; 0.0) versus 1.0 (0.0; 2.0) (P=0.001). Nugent score decreased during the intervention period by 5.5 (7.0;2.3) in the verum compared to 3.0 (6.0;0.5) in the control group (P=0.158). Additional intake of yoghurt containing these probiotic strains improved the recovery rate and symptoms of BV and tended to improve the vaginal microbial pattern.

Improving topical non-melanoma skin cancer treatment: In vitro efficacy of a novel guanosine-analog phosphonate.

Actinic keratosis, a frequent carcinoma in situ of non-melanoma skin cancer (NMSC), can transform into life-threatening cutaneous squamous cell carcinoma. Current treatment is limited due to low complete clearance rates and asks for novel therapeutic concepts; the novel purine nucleotide analogue OxBu may be an option. In order to enhance skin penetration, solid lipid nanoparticles (SLN, 136-156 nm) were produced with an OxBu entrapment efficiency of 96.5 ± 0.1%. For improved preclinical evaluation, we combined tissue engineering with clinically used keratin-18 quantification. Three doses of 10(-3) mol/l OxBu, dissolved in phosphate-buffered saline as well as loaded to SLN, were effective on reconstructed NMSC. Tumour response and apoptosis induction were evaluated by an increase in caspase-cleaved fragment of keratin-18, caspase-7 activation as well as by reduced expression of matrix metallopeptidase-2 and Ki-67. OxBu efficacy was superior to equimolar 5-fluorouracil solution, and thus the drug should be subjected to the next step in preclinical evaluation.

Effect of quercetin on traits of the metabolic syndrome, endothelial function and inflammation in men with different APOE isoforms.

BACKGROUND AND AIMS: The polyphenol quercetin may prevent cardiovascular diseases due to its vasorelaxant and anti-oxidative properties. We investigated the effects of quercetin on risk factors of atherosclerosis, biomarkers of inflammation and oxidative stress, depending on the apolipoprotein E (APOE) genotype. METHODS AND RESULTS: In a double-blind crossover study 49 healthy male subjects with APOE genotype 3/3 (n = 19), 3/4 (n = 22) and 4/4 (n = 8) consumed 150 mg/d quercetin or placebo for 8 weeks each, intermitted by a three-week washout phase. After each intervention, endothelial function, anthropometry, metabolic and inflammatory parameters were measured in the fasting and postprandial state following a standardized lipid-rich meal. Endothelial function was not changed. In all subjects combined, quercetin significantly decreased waist circumference (P = 0.004) and postprandial systolic blood pressure (P = 0.044). Postprandial triacylglycerol concentrations were significantly decreased and HDL-cholesterol concentrations increased after quercetin as compared to placebo consumption (P = 0.025). Quercetin also moderately increased levels of TNFα (P = 0.024). There was a significant gene-diet interaction for waist circumference and for body mass index (BMI). CONCLUSIONS: Quercetin supplementation improved some risk factors of cardiovascular disease, yet exerted slightly pro-inflammatory effects. Genotype-dependent effects were seen only on waist circumference and BMI.

Influence of different CLA isomers on insulin resistance and adipocytokines in pre-diabetic, middle-aged men with PPARγ2 Pro12Ala polymorphism.

Conjugated linoleic acids (CLAs) are natural PPARγ ligands, which showed conflicting effects on metabolism in humans. We examined metabolic effects of different isomers of CLA in subjects with PPARγ2 Pro12Ala polymorphisms. A total of 35 men underwent four intervention periods in a crossover study design: subjects with either genotypes received c9, t11 CLA or t10, c12 CLA, a commercially available 1:1 mix of both isomers or reference oil (linoleic acid (LA)). Adipocytokines, insulin, glucose and triglycerides were assessed in the fasting state and after a standardized mixed meal. Across all genotypes, there was a significant (p = 0.025) CLA treatment effect upon postprandial (pp) HOMA-IR values, with c9, t11 CLA and CLA isomer mix improving, but t10, c12 CLA isomer worsening. In Ala12Ala subjects, the t10, c12 isomer caused weight gain (p = 0.03) and tended to increase postprandial insulin levels (p = 0.05). In Pro12Pro subjects, t10, c12 resulted in reduction in waist circumference (p = 0.03). The comparison of the different genotype groups revealed statistically different changes in fasting and postprandial insulin, HOMA-IR and leptin after intervention. c9, t11 CLA and the commercial CLA mix showed beneficial effects on insulin sensitivity compared with LA, while t10, c12 CLA adversely affects body weight and insulin sensitivity in different PPAR genotypes. CLA isomers have different effects on metabolism in Ala and Pro carriers.

Vaccination of mice with chitosan nanogel-associated recombinant NcPDI against challenge infection with Neospora caninum tachyzoites.

The effects of nanogel encapsulation of recombinant NcPDI (recNcPDI) following vaccination of mice by intranasal or intraperitoneal routes and challenge infection with Neospora caninum tachyzoites were investigated. Nanogels were chitosan based, with an alginate or alginate-mannose surface. None of the mice receiving recNcPDI intraperitoneal (i.p.) (without nanogels) survived, whereas intranasal (i.n.) application protected 9 of 10 mice from disease. Association of recNcPDI with nanogels improved survival of i.p. vaccinated mice, but nanogels without recNcPDI gave similar protection levels. When nanogels were inoculated via the i.n. route, 80% of the mice were protected. Association of recNcPDI with the alginate-coated nanogels protected all mice against disease. Quantification of the cerebral parasite burden showed a significant reduction of parasite numbers in most experimental groups vaccinated i.n., except those vaccinated with alginate-mannose nanogels with or without recNcPDI. For i.p. vaccinated groups, no significant differences in cerebral infection densities were measured, but there was a reduction in the groups vaccinated with recNcPDI associated with both types of nanogels. Analysis of the immune responses of infected mice indicated that association of recNcPDI with nanogels altered the patterns of cytokine mRNA expression profiles, but had no major impact on the antibody subtype responses. Nevertheless, this did not necessarily relate to the protection.

Isomer-specific effects of CLA on gene expression in human adipose tissue depending on PPARgamma2 P12A polymorphism: a double blind, randomized, controlled cross-over study.

BACKGROUND: Peroxisome proliferator-activated receptor (PPAR)gamma is a key regulator in adipose tissue. The rare variant Pro12Ala of PPARgamma2 is associated with a decreased risk of insulin resistance. Being dietary PPARgamma ligands, conjugated linoleic acids (CLAs) received considerable attention because of their effects on body composition, cancer, atherosclerosis, diabetes, obesity and inflammation, although some effects were only demonstrated in animal trials and the results in human studies were not always consistent. In the present study effects of CLA supplementation on genome wide gene expression in adipose tissue biopsies from 11 Ala12Ala and 23 Pro12Pro men were investigated. Subjects underwent four intervention periods (4 wk) in a randomized double blind cross-over design receiving 4.25 g/d of either cis-9, trans-11 CLA, trans-10,cis-12 CLA, 1:1 mixture of both isomers or a reference linoleic acid oil preparation. After each intervention biopsies were taken, whole genome expression microarrays were applied, and genes of interest were verified by realtime PCR. RESULTS: The following genes of lipid metabolism were regulated by CLA: LDLR, FASN, SCD, FADS1 and UCP2 were induced, while ABCA1, CD36 and CA3 were repressed. Transcription factors PPARgamma, NFAT5, CREB5 and EBF1, the adipokine NAMPT, members of the insulin signaling cascade SORBS1 and IGF1 and IL6ST were repressed, while the adipokine THBS1 and GLUT4 involved in insulin signaling were induced. Compared to trans-10,cis-12 CLA and the CLA mixture the cis-9, trans-11 CLA isomer exerted weaker effects. Only CD36 (-1.2 fold) and THBS1 (1.5 fold) were regulated. The CLA effect on expression of PPARgamma and leptin genes depends on the PPARgamma2 genotype. CONCLUSION: The data suggest that the isomer specific influence of CLA on glucose and lipid metabolism is genotype dependent and at least in part mediated by PPARgamma. TRIAL REGISTRATION: http://www.controlled-trials.com: ISRCTN91188075.

Xenotransplantation of parathyroids in rats using barium-alginate and polyacrylic acid multilayer microcapsules.

The integrity and function of encapsulated parathyroid tissue following xenotransplantation is limited by oxygen and nutrition supply and capsule fibrosis. Since some of these factors depend on stability and biocompatibility of the coating material, multilayer microcapsules have been developed. Parathyroid tissue pieces and digested single cells from pigs were encapsulated in barium-alginate and in polyacrylic acid (PAA) multilayer capsules. After 7 days of culture the function of the encapsulated cells were assessed. Subsequently, in a part of the cultured microcapsules the viability was directly assessed whereas the other part was transplanted in dark animal [DA] rats for 30 days. After explantation viability and fibrotic reaction were examined. Single cells showed a significant increase in parathyroid hormone [PTH] secretion when exposed to medium low in calcium, whereas minced tissue pieces revealed necrosis without stimulatory responsiveness. Morphometry showed significantly better viability of single cells compared with minced tissue in vitro and in vivo. The fibrotic reaction against capsules with minced tissue was more pronounced than for capsules containing single cells. There was no difference between barium alginate and PAA capsules when containing minced tissue. In single cells, however, the fibrous tissue reaction differed significantly between barium alginate and PAA capsules. Encapsulated single cells of parathyroid tissue maintain detectable function and viability. In contrast minced tissue underwent necrosis and induced significantly more connective tissue reaction than single cells indicating an interrelationship between necrosis and fibrosis.

Improved yield and functionality of parathyroid cells separated by using collagenase-digestion with cold pre-incubation.

Preparation of cells from solid organs often induces a functional impairment due to the proteolytic cell damage by the applied digestive enzyme like collagenase, trypsin or dispase. To preserve the tissue and to enhance the yield of cells, Laue et al. reported an islet cell isolation with pre-incubation at 4 C permitting the enzyme to diffuse into the tissue and explicite activity equally throughout the whole particle. The aim of this study was to investigate whether this procedure can be applied to parathyroid glands. Therefore porcine parathyroid glands were dissected into 1 mm3 pieces. Subsequently one group of these pieces was incubated 22 h at 4 C in 2 mg/ml collagenase before activating the enzyme by elevating the temperature to 37 C for 30 min. The other group was incubated directly at 37 C for 30 min. The yield of cells and their viability was assessed by light-microscopy and staining with trypan-blue. After the cells were immobilized in barium-alginate and cultivated for 7 days, the function was tested by incubation in different calcium concentrations and PTH-measurement. Finally, the viability was assessed by histology. Using a cold pre-incubation with collagenase, a significantly higher number of isolated cells was retrieved compared with collagenase-digestion without pre-incubation. The viability was about 100% and did not differ between both groups. After immobilization and cultivation the viability decreased to less than 30%, with and without pre-incubation. In contrast to viability the PTH-secretion of the cells differed significantly between both procedures. By pre-incubation with collagenase at 4 C a gentle method is presented resulting in an enhancement of yield and function of single cells of parathyroid glands.

Probiotics--compensation for lactase insufficiency.

Yogurt and other conventional starter cultures and probiotic bacteria in fermented and unfermented milk products improve lactose digestion and eliminate symptoms of intolerance in lactose maldigesters. These beneficial effects are due to microbial beta-galactosidase in the (fermented) milk product, delayed gastrointestinal transit, positive effects on intestinal functions and colonic microflora, and reduced sensitivity to symptoms. Intact bacterial cell walls, which act as a mechanical protection of lactase during gastric transit, and the release of the enzyme into the small intestine are determinants of efficiency. There is a poor correlation between lactose maldigestion and intolerance; in some studies, low hydrogen exhalation without significant improvement of clinical symptoms was observed. Probiotic bacteria, which by definition target the colon, normally promote lactose digestion in the small intestine less efficiently than do yogurt cultures. They may, however, alleviate clinical symptoms brought about by undigested lactose or other reasons.

Wavelength tuning and spectral properties of distributed feedback diode lasers with a short external optical cavity.

We report on the wavelength tuning and spectral properties of distributed feedback (DFB) diode lasers operated with a plane external cavity (XC) mirror positioned as close as possible to the diode-laser front facet. These lasers generate single-frequency near IR radiation at wavelengths of 1392, 1580, 1602, and 1653 nm. A piezoelectric variation of the XC length provided continuous single-frequency tuning to as high as 19 GHz. A further benefit of XC DFB lasers is a residual amplitude modulation per gigahertz tuning of less than 10(-3). The XC feedback also suppresses residual side-mode oscillations to less than 60 dB. The laser's total intensity noise is close to the shot noise limit. The laser linewidth (measured in a beat note experiment) is less than 90 kHz within an acquisition time of 40 ms. The advantageous properties of XC DFB lasers for molecular spectroscopy are demonstrated by recording R(3) 2nu(3) overtone spectra of methane by single-scan single-pass absorption or frequency-modulation spectroscopy.

Effect of extracellular pH on insulin secretion and glucose metabolism in neonatal and adult rat pancreatic islets.

Changes in extracellular pH are known to affect glucose-stimulated insulin secretion. In the present study, glucose metabolism in pancreatic islets cultured at different pHs was investigated. Also, for islet transplantation purposes, insulin secretion and glucose metabolism were compared in neonatal and adult islets at different pHs to determine which islet preparation is more tolerant to acidity and alkalinity. The results revealed a dependency of insulin secretion on the external pH in both neonatal and adult islets. Reduction of insulin secretion was observed at both the acidic and alkaline sides of pH 7.3. Glucose stimulated increases of insulin secretion in all cases. Similar results were obtained for ATP and pyruvate contents. Intracellular insulin increased with the increase of pH value. In contrast, calcium content decreased with the increase of pH. The results demonstrate that neonatal islets are more acid tolerant than adult islets. Both basal and glucose-stimulated insulin secretions, as well as other parameters of neonatal islets were significantly higher than those of adult islets in response to low pH. The differences under alkaline conditions were not significant but give an indication that neonatal islets are more tolerant to alkalinity than are adult islets.

Parameters of self-organization in Hydra aggregates.

Self-organization has been demonstrated in a variety of systems ranging from chemical-molecular to ecosystem levels, and evidence is accumulating that it is also fundamental for animal development. Yet, self-organization can be approached experimentally in only a few animal systems. Cells isolated from the simple metazoan Hydra can aggregate and form a complete animal by self-organization. By using this experimental system, we found that clusters of 5-15 epithelial cells are necessary and sufficient to form de novo head-organizing centers in an aggregate. Such organizers presumably arise by a community effect from a small number of cells that express the conserved HyBra1 and HyWnt genes. These local sources then act to pattern and instruct the surrounding cells as well as generate a field of lateral inhibition that ranges up to 1,000 microm. We propose that conserved patterning systems in higher animals originate from extremely robust and flexible molecular self-organizing systems that were selected for during early metazoan evolution.

WNT signalling molecules act in axis formation in the diploblastic metazoan Hydra.

Members of the Wnt/wingless family of secreted proteins act as short-range inducers and long-range organizers during axis formation, organogenesis and tumorigenesis in many developing tissues. Wnt signalling pathways are conserved in nematodes, insects and vertebrates. Despite its developmental significance, the evolutionary origin of Wnt signalling is unclear. Here we describe the molecular characterization of members of the Wnt signalling pathway--Wnt, Dishevelled, GSK3, beta-Catenin and Tcf/Lef--in Hydra, a member of the evolutionarily old metazoan phylum Cnidaria. Wnt and Tcf are expressed in the putative Hydra head organizer, the upper part of the hypostome. Wnt, beta-Catenin and Tcf are transcriptionally upregulated when head organizers are established early in bud formation and head regeneration. Wnt and Tcf expression domains also define head organizers created by de novo pattern formation in aggregates. Our results indicate that Wnt signalling may be involved in axis formation in Hydra and support the idea that it was central in the evolution of axial differentiation in early multicellular animals.

Effect of media composition on long-term in vitro stability of barium alginate and polyacrylic acid multilayer microcapsules.

For a number of applications stability of microcapsules is a critical factor. Since the maintenance of polyelectrolyte complexes depends considerably on the ion composition we tested the physical properties of barium alginate capsules and searched for conditions to improve stability by a multilayer coating with polyethylenimine (PEI) and polyacrylic acid (PAA). Mechanical stability and diameters were determined in barium alginate capsules and compared with multilayer capsules. Multilayer coating resulted in smaller capsules than barium complexing alone. The difference was more pronounced when CaCl2 was used instead of NaCl during coating. Barium alginate capsules and application of CaCl2 during coating led to continuous pressure profiles, whereas NaCl resulted in bursting at a defined pressure, indicating the additional contribution to mechanical stability by the outer layers. After 7 d culture, mechanical stability of coated capsules decreased in RPMI and NaCl but was most pronounced in sodium citrate. The capsule diameter increased in sodium citrate, less pronounced in NaCl and was significantly different to RPMI and double distilled water. During long-term culture in RPMI, the diameter increased and mechanical stability decreased significantly. Multilayer coating improved mechanical stability which was impeded most in sodium citrate, to a lesser extent by NaCl and RPMI even after long-term exposure.