The effect of high-pressure jet processing on cocoa stability in chocolate milk.

Fat-free chocolate milk formulations containing skim milk, cocoa powder, and sugar were thermally treated and then processed using high-pressure jet (HPJ) technology from 125 to 500 MPa. The rheological properties and stability of HPJ-treated chocolate milks were compared with controls (no HPJ processing) prepared both with and without added κ-carrageenan. As expected, carrageenan-free chocolate milk exhibited immediate phase separation of the cocoa powder, whereas formulations containing κ-carrageenan were stable for 14 d. An increased stability was observed with increasing HPJ processing pressure, with a maximum observed when chocolate milk was processed at 500 MPa. The apparent viscosity at 50 s-1 of HPJ-processed samples increased from ~3 mPa·s to ~9 mPa·s with increasing pressure, and shear-thinning behavior (n < 0.9) was observed for samples processed at HPJ pressures ≥250 MPa. We suggest that HPJ-induced structural changes in casein micelles and new casein-cocoa interactions increased cocoa stability in the chocolate milk. Because casein seemed to be the major component enhancing cocoa stability in HPJ-treated samples, a second study was conducted to determine the effect of additional micellar casein (1, 2, or 4%) and HPJ processing (0-500 MPa) on the stability of fat-free chocolate milk. Formulations with 4% micellar casein processed at 375 and 500 MPa showed no phase separation over a 14-d storage period at 4°C. The addition of micellar casein together with HPJ processing at 500 MPa resulted in a higher apparent viscosity (~17 mPa·s at 50s-1) and more pronounced shear-thinning behavior (n ≤ 0.81) compared with that without added micellar casein. The use of HPJ technology to improve the dispersion stability of cocoa provides the industry with a processing alternative to produce clean-label, yet stable, chocolate milk.

Estimating anatomical trajectories with Bayesian mixed-effects modeling.

We introduce a mass-univariate framework for the analysis of whole-brain structural trajectories using longitudinal Voxel-Based Morphometry data and Bayesian inference. Our approach to developmental and aging longitudinal studies characterizes heterogeneous structural growth/decline between and within groups. In particular, we propose a probabilistic generative model that parameterizes individual and ensemble average changes in brain structure using linear mixed-effects models of age and subject-specific covariates. Model inversion uses Expectation Maximization (EM), while voxelwise (empirical) priors on the size of individual differences are estimated from the data. Bayesian inference on individual and group trajectories is realized using Posterior Probability Maps (PPM). In addition to parameter inference, the framework affords comparisons of models with varying combinations of model order for fixed and random effects using model evidence. We validate the model in simulations and real MRI data from the Alzheimer's Disease Neuroimaging Initiative (ADNI) project. We further demonstrate how subject specific characteristics contribute to individual differences in longitudinal volume changes in healthy subjects, Mild Cognitive Impairment (MCI), and Alzheimer's Disease (AD).

Individualized Gaussian process-based prediction and detection of local and global gray matter abnormalities in elderly subjects.

Structural imaging based on MRI is an integral component of the clinical assessment of patients with potential dementia. We here propose an individualized Gaussian process-based inference scheme for clinical decision support in healthy and pathological aging elderly subjects using MRI. The approach aims at quantitative and transparent support for clinicians who aim to detect structural abnormalities in patients at risk of Alzheimer's disease or other types of dementia. Firstly, we introduce a generative model incorporating our knowledge about normative decline of local and global gray matter volume across the brain in elderly. By supposing smooth structural trajectories the models account for the general course of age-related structural decline as well as late-life accelerated loss. Considering healthy subjects' demography and global brain parameters as informative about normal brain aging variability affords individualized predictions in single cases. Using Gaussian process models as a normative reference, we predict new subjects' brain scans and quantify the local gray matter abnormalities in terms of Normative Probability Maps (NPM) and global z-scores. By integrating the observed expectation error and the predictive uncertainty, the local maps and global scores exploit the advantages of Bayesian inference for clinical decisions and provide a valuable extension of diagnostic information about pathological aging. We validate the approach in simulated data and real MRI data. We train the GP framework using 1238 healthy subjects with ages 18-94 years, and predict in 415 independent test subjects diagnosed as healthy controls, Mild Cognitive Impairment and Alzheimer's disease.

Partial least squares correlation of multivariate cognitive abilities and local brain structure in children and adolescents.

Intelligent behavior is not a one-dimensional phenomenon. Individual differences in human cognitive abilities might be therefore described by a 'cognitive manifold' of intercorrelated tests from partially independent domains of general intelligence and executive functions. However, the relationship between these individual differences and brain morphology is not yet fully understood. Here we take a multivariate approach to analyzing covariations across individuals in two feature spaces: the low-dimensional space of cognitive ability subtests and the high-dimensional space of local gray matter volume obtained from voxel-based morphometry. By exploiting a partial least squares correlation framework in a large sample of 286 healthy children and adolescents, we identify directions of maximum covariance between both spaces in terms of latent variable modeling. We obtain an orthogonal set of latent variables representing commonalities in the brain-behavior system, which emphasize specific neuronal networks involved in cognitive ability differences. We further explore the early lifespan maturation of the covariance between cognitive abilities and local gray matter volume. The dominant latent variable revealed positive weights across widespread gray matter regions (in the brain domain) and the strongest weights for parents' ratings of children's executive function (in the cognitive domain). The obtained latent variables for brain and cognitive abilities exhibited moderate correlations of 0.46-0.6. Moreover, the multivariate modeling revealed indications for a heterochronic formation of the association as a process of brain maturation across different age groups.

Indirect rapid prototyping of biphasic calcium phosphate scaffolds as bone substitutes: influence of phase composition, macroporosity and pore geometry on mechanical properties.

While various materials have been developed for bone substitute and bone tissue engineering applications over the last decades, processing techniques meeting the high demands of scaffold shaping are still under development. Individually adapted and mechanically optimised scaffolds can be derived from calcium phosphate (CaP-) ceramics via rapid prototyping (RP). In this study, porous ceramic scaffolds with a periodic pattern of interconnecting pores were prepared from hydroxyapatite, ß-tricalcium phosphate and biphasic calcium phosphates using a negative-mould RP technique. Moulds predetermining various pore patterns (round and square cross section, perpendicular and 60° inclined orientation) were manufactured via a wax printer and subsequently impregnated with CaP-ceramic slurries. Different pore patterns resulted in macroporosity values ranging from about 26.0-71.9 vol% with pore diameters of approximately 340 µm. Compressive strength of the specimens (1.3-27.6 MPa) was found to be mainly influenced by the phase composition as well as the macroporosity, both exceeding the influence of the pore geometry. A maximum was found for scaffolds with 60 wt% hydroxyapatite and 26.0 vol% open porosity. It has been shown that wax ink-jet printing allows to process CaP-ceramic into scaffolds with highly defined geometry, exhibiting strength values that can be adjusted by phase composition and pore geometry. This strength level is within and above the range of human cancellous bone. Therefore, this technique is well suited to manufacture scaffolds for bone tissue engineering.

Static and dynamic cultivation of bone marrow stromal cells on biphasic calcium phosphate scaffolds derived from an indirect rapid prototyping technique.

The adequate regeneration of large bone defects is still a major problem in orthopaedic surgery. Synthetic bone substitute materials have to be biocompatible, biodegradable, osteoconductive and processable into macroporous scaffolds tailored to the patient specific defect. Hydroxyapatite (HA) and tricalcium phosphate (TCP) as well as mixtures of both phases, biphasic calcium phosphate ceramics (BCP), meet all these requirements and are considered to be optimal synthetic bone substitute materials. Rapid prototyping (RP) can be applied to manufacture scaffolds, meeting the criteria required to ensure bone ingrowth such as high porosity and defined pore characteristics. Such scaffolds can be used for bone tissue engineering (BTE), a concept based on the cultivation of osteogenic cells on osteoconductive scaffolds. In this study, scaffolds with interconnecting macroporosity were manufactured from HA, TCP and BCP (60 wt% HA) using an indirect rapid prototyping technique involving wax ink-jet printing. ST-2 bone marrow stromal cells (BMSCs) were seeded onto the scaffolds and cultivated for 17 days under either static or dynamic culture conditions and osteogenic stimulation. While cell number within the scaffold pore system decreased in case of static conditions, dynamic cultivation allowed homogeneous cell growth even within deep pores of large (1,440 mm(3)) scaffolds. Osteogenic cell differentiation was most advanced on BCP scaffolds in both culture systems, while cells cultured under perfusion conditions were generally more differentiated after 17 days. Therefore, scaffolds manufactured from BCP ceramic and seeded with BMSCs using a dynamic culture system are the method of choice for bone tissue engineering.

The resorption of nanocrystalline calcium phosphates by osteoclast-like cells.

Nanocrystalline calcium phosphates containing carbonate have a high similarity to bone mineral. The reactions of bone cells (primary osteoblasts and osteoclast-like cells) on these materials as well as on sintered beta-tricalcium phosphate and hydroxyapatite (HA) confirmed a good biocompatibility of the nanocrystalline samples. However, osteoclastic differentiation was constrained on the carbonate-rich samples, leading to a small number of osteoclast-like cells on the materials and few resorption pits. The grain size of the calcium phosphate ceramics (nano vs. micro) was less important than expected from to physico-chemical considerations. When comparing the nanocrystalline samples, the highest resorption rate was found for nano-HA with a low carbonate content, which strongly stimulated the differentiation of osteoclast-like cells on its surface.

Glutaraldehyde and oxidised dextran as crosslinker reagents for chitosan-based scaffolds for cartilage tissue engineering.

Chitosan crosslinked with glutaraldehyde or oxidised dextran was studied as a potential scaffold material in tissue engineering for cartilage regeneration. By mixing two solutions of both components it became a gel, which was frozen. After lyophilization a scaffold was generated with interconnected pores with diameters ranging between 120-350 microm. The mechanical properties (yielding point, elastic and viscous moduli), absolute porosity, pore morphology were determined depending on the ratio of chitosan to crosslinker. ATDC5 (murine cell line) and bovine articular chondrocytes (primary cells) were cultured for 14 days on the scaffolds. Cultivation with ATDC5 cells and bovine chondrocytes showed no negative influence of glutaraldehyde on cell vitality and growth.

Newly detected glucose disturbance is associated with a high prevalence of diastolic dysfunction: double risk for the development of heart failure?

Diastolic dysfunction is associated with a high rate of morbidity and mortality and has a high prevalence in patients with diabetes. Aim of the study was to investigate the prevalence of diastolic dysfunction in patients with newly detected glucose metabolism disorder (GMD) submitted for coronary angiography. Oral glucose tolerance test, echocardiography, and tissue Doppler imaging were performed in patients referred to coronary angiography. Prevalence of diastolic dysfunction was 97, 88, and 74% in the known diabetes, newly detected diabetes, and new diagnosed impaired glucose tolerance group, respectively. This is higher than previously reported. Severity of diastolic dysfunction was associated with higher 2-h plasma glucose levels and with new diagnosed diabetes. Screening patients with newly detected GMD for diastolic dysfunction may identify patients with double risk for cardiovascular morbidity and mortality and this group might be a target population to avoid development heart failure.

Assessing biological safety of metals associated with medical devices.

As human exposure to heavy metals increases, the impact these metals are having on morbidity is a growing concern. Methods of evaluating potential toxicity in medical device materials are discussed.

Effect of sucrose on physical properties of spray-dried whole milk powder.

Spray-dried whole milk powders were prepared from whole condensed milk with various sucrose concentrations (0%, 2.5%, 5%, 7.5%, and 10% w/w), and their glass transition temperature and some physical properties of importance in chocolate manufacture were evaluated. In milk powder samples, the glass transition temperature and free-fat content decreased in a nonlinear manner with sucrose addition. Moreover, increasing sucrose concentration reduced the formation of dents on the particle surface. Addition of sucrose in whole condensed milk increased linearly the apparent particle density and in a nonlinear manner the particle size of spray-dried milk powders. The particle size volume distribution of milk powders with the highest sucrose concentration differed from the log-normal distribution of the other samples due to the formation of large agglomerates. Neither vacuole volume, nor the amorphous state of milk powders was affected by sucrose addition.

Formation of osteoclast-like cells on HA and TCP ceramics.

An essential property of bone substitute materials is that they are integrated into the natural bone remodelling process, which involves the resorption by osteoclast cells and the formation by osteoblast cells. If monocyte cells adhere to a calcium phosphate surface (bone or bone substitute material), they can fuse together and form multinucleated osteoclast cells. In this study we show that osteoclast-like cells derived from a human leukoma monocytic lineage responded in a different way to tricalciumphosphate (TCP) than to hydroxyapatite (HA) ceramics. Both ceramics were degraded by resorbing cells; however, HA enhanced the formation of giant cells. The osteoclast-like cells on HA formed a more pronounced actin ring, and larger lacunas could be observed. TCP ceramics are medically used as bone substitute materials because of their high dissolution rate. On the other hand, highly soluble calcium phosphate ceramics like TCP seem to be inappropriate for osteoclast resorption because they produce a high calcium concentration in the osteoclast interface and in the environment.

3D-Cultivation of bone marrow stromal cells on hydroxyapatite scaffolds fabricated by dispense-plotting and negative mould technique.

The main principle of a bone tissue engineering (BTE) strategy is to cultivate osteogenic cells in an osteoconductive porous scaffold. Ceramic implants for osteogenesis are based mainly on hydroxyapatite (HA), since this is the inorganic component of bone. Rapid Prototyping (RP) is a new technology in research for producing ceramic scaffolds. This technology is particularly suitable for the fabrication of individually and specially tailored single implants. For tissue engineering these scaffolds are seeded with osteoblast or osteoblast precursor cells. To supply the cultured osteoblastic cells efficiently with nutrition in these 3D-geometries a bioreactor system can be used. The aim of this study was to analyse the influence of differently fabricated HA-scaffolds on bone marrow stromal cells. For this, two RP-techniques, dispense-plotting and a negative mould method, were used to produce porous ceramics. The manufactured HA-scaffolds were then cultivated in a dynamic system (bioreactor) with an osteoblastic precursor cell line. In our study, the applied RP-techniques give the opportunity to design and process HA-scaffolds with defined porosity, interconnectivity and 3D pore distribution. A higher differentiation of bone marrow stromal cells could be detected on the negative mould fabricated scaffolds, while cell proliferation was higher on the dispense-plotted scaffolds. Nevertheless, both scaffold types can be used in tissue engineering applications.

Preparation and bioactivity of novel multiblock thermoplastic elastomer/tricalcium phosphate composites.

There is a recognized need for improved treatment of osteoarthritis of the finger joints disease. Joint fusions are commonly used for treating the pain and potential deformity of arthritis. At severe deformity, artificial joint replacement is required. The most widely used are space-filler type joints made of high performance silicone rubber. One of the problems that occurs with these artificial replacements is that they can fail, because silicone elastomer used for their fabrication is relatively weak material and show to break apart and fragment. We have recently developed novel poly(aliphatic/aromatic-ester) (PED) material of sufficient mechanical properties and excellent flexibility. To enhance the bioactivity of these polymers (PED) and bone-bonding properties, PED/beta-TCP composites were prepared. The ceramic particles were homogeneously distributed during conventional blending and showed good adhesion to the polymer matrix. The thermal characteristics and mechanical properties of the composites were investigated as a function of beta-TCP content. The Youngs modulus and the yield strength of the composites increased with the increase in beta-TCP volume while the tensile strength and fracture strain decreased. In vitro investigations demonstrated an increase in cytocompatibility with increasing amount of beta-TCP up to 20 vol%.

Quantitative density profiling with pure phase encoding and a dedicated 1D gradient.

A new centric scan imaging methodology for density profiling of materials with short transverse relaxation times is presented. This method is shown to be more robust than our previously reported centric scan pure phase encode methodologies. The method is particularly well suited to density imaging of low gyro-magnetic ratio non-proton nuclei through the use of a novel dedicated one-dimensional magnetic field gradient coil. The design and construction of this multi-layer, water cooled, gradient coil is presented. Although of large diameter (7.62 cm) to maximize sample cross section, the gradient coil has an efficiency of several times that offered by conventional designs (6 mT/m/A). The application of these ideas is illustrated with high resolution density-weighted proton (1H) images of hazelnut oil penetration into chocolate, and lithium ion (7Li) penetration into cement paste. The methods described in this paper provide a straightforward and reliable means for imaging a class of samples that, until now, have been very difficult to image.

[Corrosion behaviour, metal release and biocompatibility of implant materials coated by TiO2-sol gel chemistry]. / Einfluss einer TiO2-beschichtung auf Biokompatibilität, Korrosions- und Auslaugverhalten verschiedener Implantatlegierungen.

Alloys based on titanium or cobalt have been used as implant materials for decades with good success. Because of their natural oxide layer these alloys reveal good corrosion behaviour. In contact with physiological solution metal release takes place, which can cause inflammation. Coatings can improve the corrosion behaviour. In this study Ti6Al4V and Co28Cr6Mo alloys, which are frequently used as implant materials, were tested. Polished discs of these alloys and polished discs, which were coated with TiO2-layers by sol-gel chemistry, were compared regarding their corrosion behaviour and metal ion releasing. The releasing of Al, V, Ti, Co, Cr and Mo was quantified by ICP-MS analysis. The TiO2-coating reduced the release of all ions except of the Al-ion. Both alloys showed a deviating kinetic of ion releasing. In addition, cell response (cell vitality, cell proliferation, endothelial marker CD31 and actin allocation) of osteoblasts and endothelial cells were investigated.

A novel antibacterial titania coating: metal ion toxicity and in vitro surface colonization.

Postoperative implant-associated infection is still an unresolved and serious complication in modern surgery. Antibacterial and biocompatible surfaces could both reduce infection rates and promote tissue integration. In this respect, a comparative study of the antibacterial as well as the biocompatible potential of different metal ions in vitro is presented. The assays used were growth inhibition tests with different metal salts carried out with tissue cells and bacteria under corresponding culture conditions. Additionally, in vitro tests in direct surface contact with tissue cells and bacteria onto a novel copper containing sol-gel derived titanium dioxide coating (Cu-TiO2) and a fourfold Cu-TiO2 coating were performed. The values were compared to a non-filled titanium dioxide coating and standard Ti6Al4V alloy. SEM-investigations were performed to approve the results of the in vitro tests. Among Ag+, Zn2+, Co2+, Al3+ and Hg2+, the growth inhibition tests revealed an outstanding position of copper ions as antibacterial but nevertheless bio-tolerant additive. These results were affirmed by the cell tests in direct surface contact and SEM-investigations, where best cell growth was found on the Cu-TiO2 coatings. Highest antibacterial properties with a tolerable cytocompatibility could be observed on the fourfold Cu-TiO2 coatings. Consequently, surfaces with custom-tailored antibacterial properties may be established and could be of particular interest in revision and tumor arthroplasty.

The effects of sieving and spatial variability of estuarine sediment toxicity samples on sediment chemistry.

In 1998, we conducted a field-validation study of the chronic 28-day whole-sediment toxicity test with Leptocheirus plumulosus in Baltimore Harbor, MD, an area where this amphipod is indigenous. This study included an evaluation of the effect of sieving on sediment chemical concentrations and the use of field replicates, or separate grabs from the same site, which provided an estimation of within-site chemical and toxicologic variability. Six stations in Baltimore Harbor, MD, were included in this evaluation. Chemical analysis of two separate unsieved field replicates from the six sites indicated that, overall, the chemical concentrations of replicates within each site were similar, especially for metals. Organic contaminants particularly total PCBs, had the highest variability between replicates. Chemical variability did not appear to be related to differences in organic carbon content or grain size or to variability in toxicologic end points. Results supported the use of composite samples in sediment toxicity tests. In addition, in most cases, sieving had little effect on sediment chemistry. For the metals and trace elements, only selenium showed a substantial change after sieving, with some samples increasing after sieving and others decreasing. Concentrations of acid-volatile sulfide (AVS) increased 194.6% at one station after sieving, although in most other cases, AVS and simultaneously extracted metals remained relatively unchanged. As expected, concentrations of organics generally decreased after sieving, but in the majority of cases this decrease was small (i.e., coefficient of variation < or = 25%). Total benzene hexachloride and total chlordanes had the greatest changes, whereas polychlorinated biphenyl concentrations decreased at only two stations after sieving. Concentrations of polyaromatic hydrocarbons showed little change after sieving. These changes in sediment chemistry due to sieving must be viewed in the larger context of the potentially confounding effects that indigenous organisms may have on the interpretation of test results from whole-sediment toxicity tests.

Fat, moisture, and ethanol migration through chocolates and confectionary coatings.

The migration of fat, moisture, and ethanol is a common problem with chocolate-coated confectionery products. Migration of one of these components into the coating leads to visual and sensory defects such as sugar or fat bloom, making the product unacceptable to the consumer. The migration rate depends on the structure and composition of the coating. The migration of each of these species can be slowed to a certain extent by proper tempering of the coating, because proper tempering will give a structure that resists migration. In the continuous lipid phase, these chemical species migrate mainly through the liquid portion. Thus, the migration rate depends on the amount of liquid oil present in the product. Migration can be delayed either by reducing the liquid fat content or by immobilizing the liquid phase. The actual mechanisms for the migration processes are speculative, and a more thorough understanding is necessary to better abate quality deterioration. Armed with this understanding, a manufacturer would know a priori the effect of changing the ingredient or process. A few methods for control have been suggested, but have found limited application. Mathematical models have been proposed to predict the migration behavior, but their application is hindered because of the simplified assumptions employed. There is a need for developing better models that combine mass transfer with the phase behavior to be able to accurately predict the migration process. This review discusses the current understanding of fat, moisture, and ethanol migration through chocolate coatings and also includes a brief description of the theoretical aspects governing migration.