Non-union site debridement increased the efficacy of rhBMP-2 in a rodent model

In our study we investigated the influence of debridement on bone healing in a rodent critical size defect model with and without rhBMP-2 in fibrin matrix. A total of 58 male Sprague-Dawley rats underwent a first surgical procedure where a femoral osteotomy was performed. In the single step group the defect remained empty and the specimens were collected 4 weeks later. A silicone spacer was implanted to inhibit bone healing within the defect in all the other groups. At 4 weeks the spacer was removed in a second operation with and without debridement of the bone ends and fibrin matrix alone or combined with 10 μg rhBMP-2 were applied. 4 weeks after the primary operation those specimens were collected. All the specimens were evaluated by μCT scans and histological analysis. Debridement of the defect significantly increased bone volume in the animals treated with rhBMP-2. In the control groups without growth factor application the effect of debridement was not significant concerning the union rate and the bone volume. In our experimental setting surgical debridement of the non-union site particularly promoted bone healing in combination with BMP-2 administration in fibrin matrix.

Investigation of Laplace barriers for arrayed electrowetting lab-on-a-chip

Partial-post Laplace barriers have been postulated as a means to allow electrowetting transport and geometrical reshaping of fluids, followed by the preservation of fluid geometry after the electrowetting voltage is removed. Reported here is the first investigation of Laplace barriers with the arrayed electrodes and splitting/merging transport functions for an electrowetting lab-on-a-chip. Laplace barriers optimized for 500 × 500 μm(2) electrodes and 78 μm channel height are shown to provide geometrical control of fluid shape down to radii of curvature of ~70 μm. The Laplace barriers increase the splitting volume error, but with proper electrical control, the average error in the split volume is reduced to 5%. Improved programmable fluid storage in droplets or reservoirs and continuous channel flow are also shown. This work confirms the potential benefits of Laplace barriers for lab-on-a-chip and also reveals the unique challenges and operation requirements for Laplace barriers in lab-on-a-chip applications.

Generation of retinal pigment epithelial cells from small molecules and OCT4 reprogrammed human induced pluripotent stem cells

Autologous retinal pigment epithelium (RPE) grafts derived from induced pluripotent stem cells (iPSCs) may be used to cure blinding diseases in which RPE dysfunction results in photoreceptor degeneration. Four-, two-, and one-factor-derived iPSCs (4F-, 2F-, and 1F-iPSCs, respectively) were differentiated into fully functional cuboidal pigmented cells in polarized monolayers that express RPE-specific markers. 1F-iPSCs-RPE (1F-iPS-RPE) strongly resembles primary human fetal RPE (hfRPE) based on proteomic and untargeted metabolomic analyses, and using novel in vivo imaging technology coupled with electroretinography, we demonstrated that 1F-iPS-RPE mediate anatomical and functional rescue of photoreceptors after transplantation in an animal model of RPE-mediated retinal degeneration. 1F-iPS0RPE cells were injected subretinally as a suspension and formed a monolayer dispersed between host RPE cells. Furthermore, 1F-iPS-RPE do not simply provide trophic support to rescue photoreceptors as previously speculated but actually phagocytose photoreceptor outer segments in vivo and maintain visual cycling. Thus, 1f-iPS-RPE grafts may be superior to conventional iPS-RPE for clinical use because 1F-IPS-RPE closely resemble hfRPE, mediate anatomical and functional photoreceptor rescue in vivo, and are generated using a reduced number of potentially oncogenic reprogramming factors.

Hot topic: apparent total-tract nutrient digestibilities measured commercially using 120-hour in vitro indigestible neutral detergent fiber as a marker are related to commercial dairy cattle performance

Measuring individual feed nutrient concentration is common practice for field dairy nutritionists. However, accurately measuring nutrient digestibility and using digestion values in total digestible nutrients models is more challenging. Our objective was to determine if in vivo apparent total-tract nutrient digestibility measured with a practical approach was related to commercial milk production parameters. Total mixed ration and fecal samples were collected from high-producing cows in pens on 39 commercial dairies and analyzed at a commercial feed and forage testing laboratory for nutrient concentration and 120-h indigestible NDF (iNDF) content using the Combs-Goeser in vitro digestion technique. The 120-h iNDF was used as an internal marker to calculate in vivo apparent nutrient digestibilities. Two samples were taken from each dairy and were separated in time by at least 3 wk. Samples were targeted to be taken within 7d of Dairy Herd Improvement (DHI) herd testing. Approved DHI testers measured individual cow milk weights as well as fat and protein concentrations. Individual cow records were averaged by pen corresponding to the total mixed ration and fecal samples. Formulated diet and dry matter intake (DMI) records for each respective pen were also collected. Mixed model regression analysis with dairy specified as a random effect was used to relate explanatory variables (diet nutrient concentrations, formulated DMI, in vivo apparent nutrient digestibilities, and fecal nutrient concentrations) to milk production measures. Dry matter intake, organic matter (OM) digestibility, fecal crude protein (CP) concentration, and fecal ether extract concentration were related to milk, energy-corrected milk, and fat yields. Milk protein concentration was related to CP digestibility, and milk protein yield was related to DMI, OM digestibility, CP digestibility, and ether extract digestibility. Although many studies have related DMI and OM digestibility to milk production under controlled experimental settings, very few have related practical in vivo measures to milk production. By documenting the practical OM digestibility relationship with milk production, nutritionists and scientists may have confidence in this approach for measuring diet performance and collecting nutritional data for commercial dairies.

Prevalence of alkane monooxygenase genes in Arctic and Antarctic hydrocarbon-contaminated and pristine soils

Abstract The prevalence of four alkane monooxygenase genotypes (Pseudomonas putida GPo1, Pp alkB; Rhodococcus sp. strain Q15, Rh alkB1 and Rh alkB2; and Acinetobacter sp. strain ADP-1, Ac alkM) in hydrocarbon-contaminated and pristine soils from the Arctic and Antarctica were determined by both culture-independent (PCR hybridization analyses) and culture-dependent (colony hybridization analyses) molecular methods, using oligonucleotide primers and DNA probes specific for each of the alk genotypes. PCR hybridization of total soil community DNA detected the rhodococcal alkB genotypes in most of the contaminated (Rh alkB1, 18/20 soils; Rh alkB2, 13/20) and many pristine soils (Rh alkB1, 9/10 soils; Rh alkB2, 7/10), while Pp alkB was generally detected in the contaminated soils (15/20) but less often in pristine soils (5/10). Ac alkM was rarely detected in the soils (1/30). The colony hybridization technique was used to determine the prevalence of each of the alk genes and determine their relative abundance in culturable cold-adapted (5 degrees C) and mesophilic populations (37 degrees C) from eight of the polar soils. The cold-adapted populations, in general, possessed relatively higher percentages of the Rh alkB genotypes (Rh alkB1, 1.9% (0.55); Rh alkB2, 2.47% (0.89)), followed by the Pp alkB (1.13% (0.50)), and then the Ac alkM (0.53% (0.36)). The Rh alkB1 genotype was clearly more prevalent in culturable cold-adapted bacteria (1.9% (0.55)) than in culturable mesophiles (0.41 (0.55)), suggesting that cold-adapted bacteria are the predominant organisms possessing this genotype. Overall, these results indicated that (i) Acinetobacter spp. are not predominant members of polar alkane degradative microbial communities, (ii) Pseudomonas spp. may become enriched in polar soils following contamination events, and (iii) Rhodococcus spp. may be the predominant alkane-degradative bacteria in both pristine and contaminated polar soils.

Long-term, high intake of vitamin C decreases size and increases quantity of liver mitochondria in Guinea-pigs

Microsomal cytochrome P450 is an important enzyme involved in drug metabolism and bioactivation in the liver. In guinea-pigs, the specific amount of cytochrome P450 depends on dietary vitamin C intake. Short-term vitamin C treatment can induce non-genomic effects on hepatocytes, such as activating mitochondrial respiration without changing cytochrome concentration. The aim of this investigation was to elucidate the long-term effects of a low or high vitamin C diet on the quantity and size of mitochondria in the hepatocytes of guinea-pigs. After 6 - 8 weeks of vitamin C feeding, the group receiving a low vitamin C content in their food (10 mg/100 g food) had significantly less mitochondria, but of a larger size, than the group receiving a high vitamin C content (680 mg/100 g food). This animal model investigation demonstrated that treatment with long-term vitamin C can induce morphological changes in the mitochondria of hepatocytes.

The PFA-100R cannot detect blood group-dependent inhibition of platelet function by eptifibatide or abciximab at therapeutic plasma concentrations

Previous investigations revealed that AB0 blood groups are associated with divergent concentrations of several coagulation factors. Concentrations of von Willebrand factor (vWF) and factor VIII are lower in individuals with blood group 0 compared to subjects with blood group A, B or AB, which might in turn result in a reduced inhibition of platelet aggregation in individuals with blood group 0. The aim of the present in vitro investigation was to elucidate the impact of AB0 blood group-dependent vWF concentrations on eptifibatide and abciximab mediated inhibition of GPIIb/IIIa function. Platelet function was measured with the platelet function analyzer PFA-100(R) at baseline and at increasing concentrations of eptifibatide and abciximab. It was stratified for blood group 0 vs A. If measured with the collagen/ADP cartridge, blood group 0 was associated with a prolonged mean baseline closure time in comparison with blood group A (94.3 +/- 14.6 s vs. 74.6 +/- 9.9 s, p = 0.007) which was paralleled by reduced concentrations of vWF and factor VIII. In contrast, no statistically significant differences in closure times (167.4 +/- 83.9 s vs. 140.1 +/- 99.0 s, p = 0.562) could be found in the presence of eptifibatide (0.1 microg/ml). Higher concentrations of abciximab (1 microg/ml) than those of eptifibatide were needed to increase the closure times in both cartridges of the PFA-100, but at this concentration of abciximab differences in closure times could not be detected most probably due to higher variability at these drug concentrations. The PFA-100(R) is not suitable for monitoring abciximab or eptifibatide within the therapeutic concentration range because the highest concentrations where the PFA-100(R) had measurable closure times of below 300 s is much too low to lead to the necessary platelet inhibition and, consequently, does not resemble the in vivo situation.

Coagulation status in coronary artery disease patients with type II diabetes mellitus compared with non-diabetic coronary artery disease patients using the PFA-100® and ROTEM®

Previous investigations in patients with coronary artery disease (CAD) revealed differences in thromboelastographic parameters indicating different states of coagulability. The aim of the present study was to investigate the coagulation status of patients with documented CAD and type II diabetes mellitus (DM) and non-diabetic patients with coronary artery disease with the PFA-100® and the ROTEM®. No differences were found in platelet function as measured with collagen/epinephrine (263.6 ± 70.6 s vs. 254.6 ± 65.3 s) and collagen/ADP cartridges (105.3 ± 63.2 s vs. 90.6 ± 47.3 s) in CAD patients with DM and CAD patients without DM. Measured with the EXTEM reagent of the ROTEM®, mean maximum clot elasticity (MCE) in patients with CAD and DM (233.6 ± 86.9) was significantly longer than in CAD patients without DM (186.7 ± 54.5), (p = 0.03). A similar result was seen using the INTEM reagent; patients with CAD and DM (234.4 ± 83.9) showed a higher value for MCE than CAD patients without DM (190.8 ± 57.8) which was of borderline significance (p = 0.053). Moreover, a weak trend for higher maximum clot firmness (MCF) was seen in CAD patients with DM compared with CAD patients without DM with the EXTEM reagent (68.1 ± 7.5 vs. 63.6 ± 8.6, p = 0.08) and the INTEM reagent (68.4 ± 7.2 vs. 64.1 ± 8.2, p = 0.09). The ROTEM® analysis indicates increased coagulability in patients with coronary artery disease and diabetes mellitus compared to non-diabetic CAD patients. Moreover, the ROTEM® device seems to be an appropriate and easy-to-use tool to describe the coagulation status in these patients groups.

The transient value of classifying preschool wheeze into episodic viral wheeze and multiple trigger wheeze

BACKGROUND

A recently proposed method for classifying preschool wheeze is to describe it as either episodic (viral) wheeze or multiple trigger wheeze. In research studies, phenotype is generally determined by retrospective questionnaire.

AIM

To determine whether recently proposed phenotypes of preschool wheeze are stable over time.

METHODS

In all, 132 two to six-year-old children with doctor diagnosed asthma on maintenance inhaled corticosteroids were classified as having episodic (viral) wheeze or multiple trigger wheeze at a screening visit and then followed up at three-monthly intervals for a year. At each follow-up visit, standardized questionnaires were used to determine whether the subjects wheezed only with, or also in the absence of colds. Stability of the phenotypes was assessed at the end of the study.

RESULTS

Phenotype as determined by retrospective parental report at the start of the study was not predictive of phenotype during the study year. Phenotypic classification remained the same in 45.9% of children and altered in 54.1% of children.

CONCLUSION

When children with preschool wheeze are classified into episodic (viral) wheeze or multiple trigger wheeze based on retrospective questionnaire, the classification is likely to change significantly within a 1-year period.

Effect of oral contraceptives and ovarian cycle on platelet function

In past decades, numerous epidemiological and clinical studies in women taking oral contraceptives revealed the impact of sex steroids on coagulation factors and the incidence of venous thrombosis. To date, only scarce data regarding the impact of oral contraceptives on platelet function are available. The aim of this study was to further elucidate the impact of sex steroids on platelet function. We conducted an observational study in young women using different types and dosages of monophasic oral contraceptives (OCs) compared to women not taking OCs. During the follicular phase, the mean closure time (CT) in Col/Epi was 168.0 +/- 64.9 s compared to 131.5 +/- 28.9 s during the luteal phase (p=0.012). In Col/Epi cartridges, no difference was detected between women taking second/third generation OCs and low-dose OCs (145.2 +/- 44.3 vs. 169.4 +/- 63.5, p=0.34). In contrast, mean Col/Epi values of women using anti-androgen-containing OCs were less (110.3 +/- 15.6 s) than in both other OC groups (p=0.03 for both comparisons). The same holds for Col/Epi values from women during the follicular- and luteal phases compared to women using anti-androgen-containing OCs (p=0.0002, p=0.013). Significant correlations between progesterone and platelet function in women not using OCs (p=0.02) could be found. In conclusion, the results of the study show that platelet function might be modulated by OCs and the female cycle. As for OCs, the main factor seems to be the progestagen. During the female cycle, the main impact on platelet function might be mediated by progesterone.

A discrete dynamics model for synchronization of pulse-coupled oscillators

Biological information processing systems employ a variety of feature types. It has been postulated that oscillator synchronization is the mechanism for binding these features together to realize coherent perception. A discrete dynamic model of a coupled system of oscillators is presented. The network of oscillators converges to a state where subpopulations of cells become phase synchronized. It has potential applications to describing biological perception as well as for the construction of multifeature pattern recognition systems. It is shown that this model can be used to detect the presence of short line segments in the boundary contour of an object. The Hough transform, which is the standard method for detecting curve segments of a specified shape in an image was found not to be effective for this application. Implementation of the discrete dynamics model of oscillator synchronization is much easier than the differential equation models that have appeared in the literature. A systematic numerical investigation of the convergence properties of the model has been performed and it is shown that the discrete dynamics model can scale up to large number of oscillators.

Beer consumption reduces cerebral oxidation caused by aluminum toxicity by normalizing gene expression of tumor necrotic factor alpha and several antioxidant enzymes

Aluminum (Al)-induced neurotoxicity is well known and different salts of aluminum have been reported to accelerate oxidative damage to biomolecules. The present study has examined whether silicon consumed in the form of silicic acid or beer could potentially inhibit aluminum toxicity in the brain. Male mice were administered with Al(NO(3))(3) orally at a dose of 450 mg/kg/day in drinking water for 3 month. Experimental mice were given Al(NO(3))(3) along with 50 mg/L of silicic acid or with 0.5 ml/day of beer. Al brain levels in the Al group were four times higher than those of control mice while silicic acid and beer group values were 40% lower than those of the Al group. We have observed that beer prevented accumulation of lipid damage significantly, which resulted from aluminum intake. Decline in the expression of mRNA of endogenous antioxidant enzymes associated with aluminum administration was also inhibited by beer and silicic acid. The tumor necrosis factor alpha (TNFalpha) RNA expression was normalized in silicic acid and beer groups. Very high and significant correlations were found for the different parameters tested suggesting that moderate consumption of beer, due to its silicon content, effectively protects against the neurotoxic effects of aluminum.