Gaussian Process-based prediction of memory performance and biomarker status in ageing and Alzheimer's disease-A systematic model evaluation

Neuroimaging markers based on Magnetic Resonance Imaging (MRI) combined with various other measures (such as genetic covariates, biomarkers, vascular risk factors, neuropsychological tests etc.) might provide useful predictions of clinical outcomes during the progression towards Alzheimer's disease (AD). The use of multiple features in predictive frameworks for clinical outcomes has become increasingly prevalent in AD research. However, many studies do not focus on systematically and accurately evaluating combinations of multiple input features. Hence, the aim of the present work is to explore and assess optimal combinations of various features for MR-based prediction of (1) cognitive status and (2) biomarker positivity with a multi-kernel learning Gaussian process framework. The explored features and parameters included (A) combinations of brain tissues, modulation, smoothing, and image resolution; (B) incorporating demographics & clinical covariates; (C) the impact of the size of the training data set; (D) the influence of dimensionality reduction and the choice of kernel types. The approach was tested in a large German cohort including 959 subjects from the multicentric longitudinal study of cognitive impairment and dementia (DELCODE). Our evaluation suggests the best prediction of memory performance was obtained for a combination of neuroimaging markers, demographics, genetic information (ApoE4) and CSF biomarkers explaining 57% of outcome variance in out-of-sample predictions. The highest performance for Aβ42/40 status classification was achieved for a combination of demographics, ApoE4, and a memory score while usage of structural MRI further improved the classification of individual patient's pTau status.

Inputs of disinfection by-products to the marine environment from various industrial activities: Comparison to natural production

Oxidative treatment of seawater in coastal and shipboard installations is applied to control biofouling and/or minimize the input of noxious or invasive species into the marine environment. This treatment allows a safe and efficient operation of industrial installations and helps to protect human health from infectious diseases and to maintain the biodiversity in the marine environment. On the downside, the application of chemical oxidants generates undesired organic compounds, so-called disinfection by-products (DBPs), which are discharged into the marine environment. This article provides an overview on sources and quantities of DBP inputs, which could serve as basis for hazard analysis for the marine environment, human health and the atmosphere. During oxidation of marine water, mainly brominated DBPs are generated with bromoform (CHBr₃) being the major DBP. CHBr₃ has been used as an indicator to compare inputs from different sources. Total global annual volumes of treated seawater inputs resulting from cooling processes of coastal power stations, from desalination plants and from ballast water treatment in ships are estimated to be 470-800 × 10⁹ m³, 46 × 10⁹ m³ and 3.5 × 10⁹ m³, respectively. Overall, the total estimated anthropogenic bromoform production and discharge adds up to 13.5-21.8 × 10⁶ kg/a (kg per year) with contributions of 11.8-20.1 × 10⁶ kg/a from cooling water treatment, 0.89 × 10⁶ kg/a from desalination and 0.86 × 10⁶ kg/a from ballast water treatment. This equals approximately 2-6% of the natural bromoform emissions from marine water, which is estimated to be 385-870 × 10⁶ kg/a.

Abstract P3-08-18: Clinicopathological characteristics associated with intermediate and high-risk ODx RS

Background: The gene expression profiling assay OncotypeDx (ODx) prognosticates the risk of estrogen receptor positive (ER+) breast cancer (BC) recurrence and assesses the likely benefit from adjuvant chemotherapy in addition to endocrine therapy. There have been several attempts to develop algorithms that provide similar outcome prediction to the ODx assay with the use of routine clinicopathological characteristics. These models appear to predict high-risk ODx RS but are unable to reliably rule out the presence of patients with intermediate-risk disease. Our objective was to identify the clinicopathological factors associated with intermediate and high-risk categories.

Methods: We retrospectively reviewed the electronic medical records of patients with early-stage ER+ BC for whom ODx recurrence score (RS) was available. Patients were diagnosed and treated at 3 specialized cancer centers between 2010 and 2017. Two multinomial logistic regression models (crude and adjusted) were constructed to assess the association between clinicopathological characteristics and ODx RS as a categorical variable. The adjusted model included the following variables: ODx RS, age, tumor size, node status, grade, lymphovascular invasion and hormonal receptors. The reported association measure was the relative prevalence ratio (RPR) with its respective 95%CI.

Results: A total of 551 patients were included. Patients had a mean age of 56.2 ± 11.9 (SD) (range: 26-89). 9.6% (n=53) of patients were≤40 years old.The size of the tumors ranged from 0.1 cm to 7.2 cm (median = 1.5 cm; IQR 1.0-2.2cm). A minority of patients had lymph node involvement (5.8%, n=32). By subtype, carcinomas were mostly ductal (83.5%, n=460), followed by lobular (10.0%, n=55) and mucinous (3.5%, n=19). The majority of tumor exhibited an intermediate histological grade (71.6%, n=386). Ki 67 was available in 58.8% patients (n= 324), with a median Ki67 of 20 (IQR 10-30). In the adjusted multinomial logistic regression model, factors associated with ODx intermediate-risk category were grade 3 (RPR=4.78; 95%CI: 2.01-11.39) and having either ER or PR <50 (RPR=2.80; 95%CI: 1.83-4.27). Factors associated with ODx high-risk category were grade 3 (RPR=15.89; 95%CI: 3.23-78.19), having either ER or PR <50 (RPR=4.58; 95%CI: 2.37-8.87), age≤40 (RPR=2.96; 95%CI: 1.20-7.29) and T2-3 (RPR=2.20; 95%CI: 1.13-4.32).

Conclusion: Grade 3, ER o PR <50, age ≤40 years and T2-3 are clinicopathological characteristics strongly associated with high-risk ODx RS. The associations with intermediate-risk ODx RS are weaker. The way these factors could be integrated into a clinicopathologic risk prediction model to identify high-risk patients needs further analysis.

Citation Format: Ruiz R, Morante Z, Namuche F, Urrunaga D, Leon M, Ziegler G, Aguilar A, Chavez Mac Gregor M, Gomez H. Clinicopathological characteristics associated with intermediate and high-risk ODx RS [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-08-18.

Abstract P3-08-16: Age's importance in early breast cancer: Oncotype Dx results in patients ≤40 years

Background

The 21-gene recurrence score (RS) predicts the benefit of adjuvant chemotherapy (CT) in ER-positive HER2-negative breast cancer (BC) and has been validated in population where women under 40 are underrepresented.Young BC pts are more likely to receive adjuvant chemotherapy (CT) in addition to endocrine therapy (ET). Our objective was to assess the RS results in young (≤40 yo) vs older (>40 yo) pts and evaluate the impact of age on clinical decision-making according to RS categories.

Methods

We retrospectively reviewed electronic medical files of all patients with early stage hormone receptor BC for whom RS was available between 2007 and 2017 in 3 specialized cancer centers. We used the Mann-Whitney and Chi-squared tests to assess differences between age group. Similarly, we evaluated the association between age groups and treatment, within each ODx category. To determine if age was associated with CT use in the low risk category, a logistic regression model was constructed.

Results

A total of 551 pts were included, 53 (9.6%) ≤40 yo and 498 (90.4%) >40 yo. No statistical differences were found between the younger and older groups in T (p=0.874), N (p=0.794), stage (p=0.188), or grade (p=0.791). Young patients underwent radical surgery more frequently than their older counterparts (41.5 vs 25.7%, p=0.014). Statistically significant differences were also observed in ER mean, which was lower in the younger group (80 vs 90%, p<0.001). The median RS result was significantly higher in the younger group (19 vs 16, p=0.009). Also, high-risk recurrence score category was significantly more frequent in the younger group (22.6 vs 9.2%, p=0.009). In the intermediate-risk category there were no differences in the proportion of patients who received CT according to age groups (p=0.484). In the low-risk category, 28.0% of patients ≤40 years vs 11.3% of patients >40 years received CT (p=0.037).

Conclusions

Our results indicate that RS tends to be higher in patients with BC ≤ 40 yo and that the frequency of high-risk RS is significantly higher in the younger group, suggesting biological differences between groups. 28% of young patients with low-risk RS from our cohort are overtreated. Based on these results, it should be considered to develop a test adjusted to the age of the patients.

Citation Format: Ruiz R, Namuche F, Morante Z, Aguilar A, Urrunaga D, Ziegler G, Chavez Mac Gregor M, Leon M, Gomez H. Age's importance in early breast cancer: Oncotype Dx results in patients ≤40 years [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-08-16.

Abstract P3-08-17: Evaluation of Oncotype DX testing and subsequent treatment choices in the Latin American setting

Background: The gene expression profiling assay OncotypeDx (ODx) prognosticates the risk of estrogen receptor positive (ER+) breast cancer (BC) recurrence and assesses the likely benefit from adjuvant chemotherapy in addition to endocrine therapy. Numerous clinical utility studies have shown that acknowledging the RS impacts on clinical decision making, leading to a decrease in chemotherapy (CT) use. However, the cost of the assay limits it widespread use, especially in low and middle-income countries. Our objective was to determine the patterns of use of ODx, its results and the subsequent treatment choices in a large Latin American cohort.

Methods: We retrospectively reviewed the electronic medical records of patients with early-stage ER+ BC for whom ODx recurrence score (RS) was available. Patients were diagnosed and treated at 3 specialized Peruvian cancer centers between 2007 and 2017. Descriptive results for numeric variables were presented as means with standard deviation (SD) or medians with interquartile range (IQR), depending on their distributions; otherwise, we expressed the qualitative variables as numbers with percentages. We evaluated the association between ODx RS category and treatment using the Chi-squared test.

Results: A total of 551 patients were included. Patients had a mean age of 56.2 ± 11.9 (SD) (range: 26-89). 9.6% (n=53) of patients were ≤40 years old. The size of the tumors ranged from 0.1 cm to 7.2 cm (median = 1.5 cm; IQR 1.0-2.2cm). 36 (6.5%) patients had tumors ≤ 0.5cm and 7 (1%) had tumors > 5cm. A minority of patients had lymph node involvement (5.8%, n=32). ODx was ordered in 55 cases (10%) of lobular carcinoma and in 23 cases (4%) of favorable histology tumors (19 mucinous, 4 tubular). Most tumors exhibited an intermediate histological grade (71.6%, n=386). Ki67 was available in 58.8% patients (n= 324), with a median Ki67 of 20 (IQR 10-30). Using commercial cutoffs RS was distributed as follows: low (0–17) = 316 (57.4%), intermediate (18–30) = 177 (32.1%), and high (≥31) = 58 (10.5%). In general, 57.5% (n=317) of patients received endocrine therapy (ET) as their only systemic treatment and 42.5% (n=234), also received CT (ET + CT). In the low-risk category, 87.3% (n=276) of patients received ET and 12.7% (n=40), ET + CT. Within the intermediate-risk category, most patients received ET + CT (77.4%, n=137). Only one patient in the high-risk category did not receive CT. There was a significant association between the RS group and treatment choice (p<0.001).

Impact of ODx RS results on treatment recommendations Oncotype risk categories  LowIntermediateHighp valueTreatmentn%n%n%<0.001Endocrine therapy27687.34022.611.7 Chemotherapy + Endocrine therapy4012.713777.45798.3 

Conclusion: ODx significantly influenced treatment decisions in our cohort, however an overutilization of CT was found in low-risk patients. Further data analysis is needed to explain the higher than expected use of CT. Also, there is room for improvement in the selection of cases that undergo ODx testing.

Citation Format: Ruiz R, Morante Z, Namuche F, Urrunaga D, Aguilar A, Schwarz J, Leon M, Ziegler G, Chavez Mac Gregor M, Gomez H. Evaluation of Oncotype DX testing and subsequent treatment choices in the Latin American setting [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-08-17.

Oxidative Stress and Cardiovascular Risk in Type 1 Diabetes Mellitus: Insights From the DCCT/EDIC Study

Background

Hyperglycemia leading to increased oxidative stress is implicated in the increased risk for the development of macrovascular and microvascular complications in patients with type 1 diabetes mellitus.

Methods and Results

A random subcohort of 349 participants was selected from the DCCT / EDIC (Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications) cohort. This included 320 controls and 29 cardiovascular disease cases that were augmented with 98 additional known cases to yield a case cohort of 447 participants (320 controls, 127 cases). Biosamples from DCCT baseline, year 1, and closeout of DCCT , and 1 to 2 years post‐ DCCT ( EDIC years 1 and 2) were measured for markers of oxidative stress, including plasma myeloperoxidase, paraoxonase activity, urinary F 2α isoprostanes, and its metabolite, 2,3 dinor‐8 iso prostaglandin F 2α . Following adjustment for glycated hemoblobin and weighting the observations inversely proportional to the sampling selection probabilities, higher paraoxonase activity, reflective of antioxidant activity, and 2,3 dinor‐8 iso prostaglandin F 2α , an oxidative marker, were significantly associated with lower risk of cardiovascular disease (−4.5% risk for 10% higher paraoxonase, P <0.003; −5.3% risk for 10% higher 2,3 dinor‐8 iso prostaglandin F 2α , P =0.0092). In contrast, the oxidative markers myeloperoxidase and F 2α isoprostanes were not significantly associated with cardiovascular disease after adjustment for glycated hemoblobin. There were no significant differences between DCCT intensive and conventional treatment groups in the change in all biomarkers across time segments.

Conclusions

Heightened antioxidant activity (rather than diminished oxidative stress markers) is associated with lower cardiovascular disease risk in type 1 diabetes mellitus, but these biomarkers did not change over time with intensification of glycemic control.

Clinical Trial Registration

URL : https://www.clinicaltrials.gov . Unique identifiers: NCT 00360815 and NCT 00360893.

Multivariate Analysis of the Cotton Seed Ionome Reveals a Shared Genetic Architecture

To mitigate the effects of heat and drought stress, a better understanding of the genetic control of physiological responses to these environmental conditions is needed. To this end, we evaluated an upland cotton (Gossypium hirsutum L.) mapping population under water-limited and well-watered conditions in a hot, arid environment. The elemental concentrations (ionome) of seed samples from the population were profiled in addition to those of soil samples taken from throughout the field site to better model environmental variation. The elements profiled in seeds exhibited moderate to high heritabilities, as well as strong phenotypic and genotypic correlations between elements that were not altered by the imposed irrigation regimes. Quantitative trait loci (QTL) mapping results from a Bayesian classification method identified multiple genomic regions where QTL for individual elements colocalized, suggesting that genetic control of the ionome is highly interrelated. To more fully explore this genetic architecture, multivariate QTL mapping was implemented among groups of biochemically related elements. This analysis revealed both additional and pleiotropic QTL responsible for coordinated control of phenotypic variation for elemental accumulation. Machine learning algorithms that utilized only ionomic data predicted the irrigation regime under which genotypes were evaluated with very high accuracy. Taken together, these results demonstrate the extent to which the seed ionome is genetically interrelated and predictive of plant physiological responses to adverse environmental conditions.

Genomewide association study of ionomic traits on diverse soybean populations from germplasm collections

The elemental content of a soybean seed is a determined by both genetic and environmental factors and is an important component of its nutritional value. The elemental content is chemically stable, making the samples stored in germplasm repositories an intriguing source of experimental material. To test the efficacy of using samples from germplasm banks for gene discovery, we analyzed the elemental profile of seeds from 1,653 lines in the USDA Soybean Germplasm Collection. We observed large differences in the elemental profiles based on where the lines were grown, which lead us to break up the genetic analysis into multiple small experiments. Despite these challenges, we were able to identify candidate single nucleotide polymorphisms (SNPs) controlling elemental accumulation as well as lines with extreme elemental accumulation phenotypes. Our results suggest that elemental analysis of germplasm samples can identify SNPs in linkage disequilibrium to genes, which can be leveraged to assist in crop improvement efforts.

Integration of Experiments across Diverse Environments Identifies the Genetic Determinants of Variation in Sorghum bicolor Seed Element Composition

Seedling establishment and seed nutritional quality require the sequestration of sufficient element nutrients. The identification of genes and alleles that modify element content in the grains of cereals, including sorghum (Sorghum bicolor), is fundamental to developing breeding and selection methods aimed at increasing bioavailable element content and improving crop growth. We have developed a high-throughput work flow for the simultaneous measurement of multiple elements in sorghum seeds. We measured seed element levels in the genotyped Sorghum Association Panel, representing all major cultivated sorghum races from diverse geographic and climatic regions, and mapped alleles contributing to seed element variation across three environments by genome-wide association. We observed significant phenotypic and genetic correlation between several elements across multiple years and diverse environments. The power of combining high-precision measurements with genome-wide association was demonstrated by implementing rank transformation and a multilocus mixed model to map alleles controlling 20 element traits, identifying 255 loci affecting the sorghum seed ionome. Sequence similarity to genes characterized in previous studies identified likely causative genes for the accumulation of zinc, manganese, nickel, calcium, and cadmium in sorghum seeds. In addition to strong candidates for these five elements, we provide a list of candidate loci for several other elements. Our approach enabled the identification of single-nucleotide polymorphisms in strong linkage disequilibrium with causative polymorphisms that can be evaluated in targeted selection strategies for plant breeding and improvement.

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.

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We propose an approach to support individualized clinical decisions in elderlies.

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Gaussian process models are used to build a normative generative model of aging.

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It affords probabilistic predictions of local gray matter volume in subjects.

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We validate the model using simulated and large real MRI data samples.

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, β-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.

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.

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.

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.

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.

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%.

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.

Phantom materials for single point imaging pulse sequences

The popularity of pure phase encode MRI techniques, including single point imaging (SPI), is steadily increasing, particularly in instances where the samples of interest are solid-like, or for other reasons possess short effective transverse relaxation times, T2*. As the interest in these techniques grows, so too does the need for a phantom material which is representative of this class of samples. The characteristics of such a phantom should include chemical and physical stability, straightforward preparation, high signal to noise ratio and relaxation times which are both easily manipulated and representative. To this end, we have developed a gelatin/sucrose-based gel which addresses the above criteria and behaves as a very flexible short T2* phantom. An order of magnitude variation in T1 and T2 can be achieved over a reasonable range of sucrose concentration. Even larger changes can be achieved with the addition of further doping agents.

Einfluss einer TiO2-Beschichtung auf Biokompatibilität, Korrosionsund Auslaugverhalten verschiedener Implantatlegierungen / Corrosion behaviour, metal release and biocompatibility of implant materials coated by TiO2-sol gel chemistry

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.

Efficacy and tolerability of valerian extract LI 156 compared with oxazepam in the treatment of non-organic insomnia--a randomized, double-blind, comparative clinical study

Patients aged 18 to 73 years and diagnosed with non-organic insomnia according to ICD-10 (F 51.0) were treated in a multicentre, double-blind, randomised parallel group comparison with either 600 mg/die valerian extract LI 156 (Sedonium) or 10 mg/die oxazepam taken for 6 weeks. A total of 202 outpatients with a mean duration of insomnia of 3.5 months at baseline were included at 24 study centres (general practices) in Germany. - Sleep quality (SQ) after 6 weeks measured by the Sleep Questionnaire B (SF-B; CIPS 1996) showed that 600 mg/die valerian extract LI 156 was at least as efficacious as a treatment with 10 mg/die oxazepam. Both treatments markedly increased sleep quality compared with baseline (p <0.01). The other SF-B subscales, i.e. feeling of refreshment after sleep (GES), psychic stability in the evening (PSYA), psychic exhaustion in the evening (PSYE), psychosomatic symptoms in the sleep phase (PSS), dream recall (TRME), and duration of sleep confirmed similar effects of both treatments. Clinical Global Impressions scale (CGI) and Global Assessment of Efficacy by investigator and patient, again, showed similar effects of both treatments. Adverse events occurred in 29 patients (28.4%) receiving valerian extract LI 156 and 36 patients (36.0%) under oxazepam, and were all rated mild to moderate. No serious adverse drug reactions were reported in either group. Most patients assessed their respective treatment as very good (82.8% in the valerian group, 73.4% in the oxazepam group). During the 6 week treatment phase Valerian extract LI 156 (Sedonium) 600 mg/die showed a comparable efficacy to 10 mg/die oxazepam in the therapy of non-organic insomnia.

Matrix metalloproteinase-like activity from hemocytes of the eastern oyster, Crassostrea virginica

Investigation of oyster blood cell lysate revealed one prominent band of proteolytic activity when analyzed using gelatin and collagen impregnated polyacrylamide gel electrophoresis. The proteolytic activity was inhibited by 1,10 phenanthroline and EDTA, but not by other proteinase inhibitors. Maximal activity was shown at pH 8.2 and the molecular weight of the protein responsible for the activity was estimated to be 68 kDa. Proteolytic activity was also measured by fluorescence assays containing hemocyte lysate and fluorescein-labeled gelatin, type I or type IV collagen. Characteristics of this proteolytic activity suggest that an invertebrate matrix metalloproteinase is responsible.

[Interventional therapy after failed fibrinolysis in acute myocardial infarct. Acute and long-term outcome of referral for rescue balloon angioplasty]

BACKGROUND

The results from studies of coronary angioplasty after failed thrombolysis (rescue-PTCA) in acute myocardial infarction are contradictory. Long-term results were not presented till now. Therefore we analyzed the data from our registry of those patients whose acute and long-term results were available.

PATIENTS AND METHODS

Data of 49 patients were analyzed who had been admitted for rescue-PTCA from other hospitals. Thrombolysis had to be started < 6 hours (mean 2.7 hours) from onset of symptoms. Rescue-PTCA had to be completed within < 24 hours (mean 10.5 hours). 37 patients received streptokinase, seven rt-PA, three urokinase and two prourokinase. Electrocardiographic and clinical criteria were used to define failure of thrombolysis. The data of the acute results were from a prospective registry and the long-term results came from clinical follow-up visits and a questionnaire sent to the patients.

RESULTS

Mean age of the patients was 48.5 years (38-78 years), 45 male, nine patients in cardiogenic shock (18%), infarct related artery (IRA): RCA 22x, LAD 21x, LCX 5x, CABG 1x, single vessel disease 27x, multiple vessel disease 22x. Acute results: Initial IRA-TIMI flow 0 in 28 patients, 1 in twelve patients, 2 in 9 patients; after rescue-PTCA TIMI flow 1 in one patient, 2 in two patients, 3 in 46 patients (procedural success 94%). Hospital mortality 8.2% (four patients), all in cardiogenic shock. Early reocclusion rate 10%. Bleeding complications 14%, no fatal complications. Long-term results: Observation period 2.5 years in 42 patients (0.5-6.5 years). Three more deaths. Total mortality 14% (7/49). Angiographic follow-up: Ejection fraction initially 50%; 53% after 3 months. Repeat revascularization in 43% (15/35): Re-PTCA in 8/35, surgery in 6/35 patients, 1x transplantation. 80% of the patients were free from angina or heart failure.

CONCLUSIONS

Rescue-PTCA in acute myocardial infarction has a high procedural success rate with a low hospital mortality. It is the treatment of choice for patients in cardiogenic shock. Transportation to an interventional center is safe. The reintervention rate is comparably high. The long-term results are good.

Expression of altered alpha2-adrenergic phenotypic traits in normotensive humans at genetic risk of hereditary (essential) hypertension

BACKGROUND

Essential (hereditary) hypertension is a common, though complex, trait with substantial heritability, but a still-obscure mode of inheritance. In this disorder with relatively late onset, knowledge of phenotypes with earlier penetrance would aid genetic analyses, as well as assessment of risk.

OBJECTIVE

Because alpha2-adrenergic receptor alterations are among the most heritable in experimental genetic hypertension, we hypothesized enhanced expression of alpha2-adrenergic phenotypic traits in still-normotensive humans at genetic risk of hypertension.

METHODS

We evaluated hemodynamic (blood pressure, cardiac output, systemic vascular resistance, stroke volume, and cardiac contractility) and biochemical (plasma drug, catecholamine, renin, and chromogranin A levels) responses to alpha2-adrenergic blockade with intravenous yohimbine in 84 normotensive subjects stratified by genetic risk of essential hypertension (67 with positive family histories and 17 with negative family histories of hypertension), as well as 18 subjects with established essential hypertension. Results were evaluated by analysis of variance, normal likelihood ratio test, and by maximum likelihood analysis for bimodality (i.e. mixtures) of response distributions.

RESULTS

Blood pressure rose (P<0.001) during alpha2-adrenergic blockade, with greater response (P<0.001) in members of the hypertensive than in members of the normotensive group. Hemodynamically, the rise in blood pressure resulted from an increase in cardiac output (P<0.001), with associated increases in stroke volume (P=0.002) and cardiac contractility (P=0.006), without an overall change in systemic vascular resistance. Biochemically, plasma norepinephrine (P<0.001), epinephrine (P=0.001), and chromogranin A (P=0.02) rose, suggesting augmentation of efferent exocytotic sympathoadrenal activity. Cardiac output and stroke volume responses were correlated to increments in plasma catecholamines (especially epinephrine) for the positive group, but not for the negative group. Baseline plasma catecholamines predicted increments of stroke volume after administration of yohimbine (P=0.003-0.007) for the positive but not for the negative group. Simultaneous comparison of means and variances of cardiac output and stroke volume alpha2-adrenergic responses, by using a normal likelihood ratio test, revealed highly significant (P=0.025 to P<0.0001) differences between the groups of subjects with and without family histories of hypertension. Frequency histogram suggested that there was a bimodal distribution of responses of stroke volume to alpha2-adrenergic blockade for the normotensive group with positive family histories of hypertension; maximum likelihood analysis strongly rejected the hypothesis of a unimodal distribution, whereas the hypothesis of bimodality could not be rejected (chi2=18.4, P=0.0004). The second (exaggerated) mode of response of stroke volume to alpha2-adrenergic blockade, defined by maximum likelihood analysis, was found for 9.5% of subjects in the normotensive group with positive family histories of hypertension, and was characterized by significantly different responses of cardiac output (P=0.001), stroke volume (P<0.001), contractility (P<0.001), heart rate (P=0.03), systemic vascular resistance (P<0.001), and epinephrine (P<0.001). Even prior to alpha2-adrenergic blockade, baseline stroke volume (P=0.01), heart rate (P=0.04), systemic vascular resistance (P=0.005), and catecholamine (P=0.001-0.005) values for this subgroup were different than control values.

CONCLUSIONS

We conclude that heterogeneous, bimodally distributed hemodynamic responses to alpha2-adrenergic blockade in subjects with positive family histories of hypertension suggest a discrete subgroup with early expression of perhaps Mendelian traits associated with risk of later development of hypertension. Such phenotypic traits ('intermediate phenotypes'), with earlier penetrance than hypertension itself, can be

Inhibition of dextromethorphan metabolism by moclobemide

This pilot study was conducted to evaluate the potential of the new antidepressant moclobemide to inhibit the cytochrome enzyme P4502D6 (CYP2D6) using the cough suppressant dextromethorphan as a substrate in four extensive metabolizers (EM) of debrisoquine. The subjects received seven oral doses of 20 mg dextromethorphan at 4-h intervals over 2 days (1 and 2) and subsequently moclobemide (300 mg b.i.d.) for 9 days. On days 10 and 11, they received seven doses of 20 mg dextromethorphan in addition to moclobemide. During monotreatment and combined treatment, blood was collected on days 2 and 11, respectively, for determination of dextromethorphan and its demethylated metabolites using automated high-performance liquid chromatography with column switching. Concurrent administration of moclobemide markedly reduced the O-demethylation of dextromethorphan, whereas the N-demethylation of dextrorphan to hydroxymorphinan was not affected. The findings indicate that moclobemide can affect the pharmacokinetics of drugs that are mainly metabolized by CYP2D6.