Androgen therapy does not prevent bone loss and arterial calcifications in male rats with chronic kidney disease.

Patients suffering from chronic kidney disease (CKD) often experience bone loss and arterial calcifications. It is unclear if hypogonadism contributes to the development of these complications and whether androgen therapy might prevent them. Male adult rats were randomized into four groups. The first group received standard chow (control), while three other groups were fed a 0.25% adenine/low vitamin K diet (CKD). Two CKD groups were treated with testosterone or dihydrotestosterone (DHT), whereas the control group and one CKD group received vehicle (VEH). CKD animals had 10-fold higher serum creatinine and more than 15-fold higher parathyroid hormone levels compared to controls. Serum testosterone levels were more than two-fold lower in the CKDVEH group compared to control + VEH and CKD + testosterone groups. Seminal vesicle weight was reduced by 50% in CKDVEH animals and restored by testosterone and DHT. CKD animals showed a low bone mass phenotype with decreased trabecular bone volume fraction and increased cortical porosity, which was not rescued by androgen treatment. Aortic calcification was much more prominent in CKD animals and not unequivocally prevented by androgens. Messenger RNA expression of the androgen receptor-responsive genes Acta1 and Col1a1 was reduced by CKD and stimulated by androgen treatment in levator ani muscle but not in the bone or aortic tissue. We conclude that adenine-induced CKD results in the development of hypogonadism in male rats. Androgen therapy is effective in restoring serum testosterone levels and androgen-sensitive organ weights but does not prevent bone loss or arterial calcifications, at least not in the presence of severe hyperparathyroidism.

[Innovative methods and developments in oral care. 3D planning in oral and maxillofacial surgery]. / Serie: Innovatieve technieken en ontwikkelingen in de mondzorg. 3D-planning in de mka-chirurgie.

With the use of cone beam computed tomography, intraoral scanning and 3D stereophotogrammetry, a virtual 3D head model of a patient can be reconstructed with image fusion. In this way, the malposition, deficiency and other anomalies at the level of bone, dentition and soft tissue can be quantified objectively. The desired position of the dentition, occlusion and soft tissue in the facial profile can be virtually drawn in and used as a guideline for treatment planning. Based on the principle of backward planning, it is possible to determine what repositioning of the jaw is required, where there is a need for bone augmentation and how many dental implants are necessary to obtain the desired treatment outcome. From this perspective, 3D treatment planning has become a treatment standard for the 4 clinical pillars supporting oral and maxillofacial surgery, specifically orthognathic surgery, implantology, craniofacial surgery and head & neck oncology. 3D planning has influenced today's workflow, planning of complex surgery and contributed to useful further innovations and efficient healthcare.

[The 3D-printed surgical guides used during genioplasty]. / De 3D-geprinte zaag- en repositiemal voor een kinplastiek.

Genioplasty is a seemingly simple procedure performed to correct the bony chin. The results of the procedure are, however, strongly correlated with the experience of the surgeon. 3D-printed surgical guides could act as a transfer modality to translate the preoperative planning directly into the achieved result. Prospective studies evaluating the usefulness of the 3D-printed surgical guides have not yet been carried out and consensus regarding the best design is lacking. In order to become more familiar with working with surgical guides, a genioplasty using 3D-printed surgical guides was performed. The postoperative analysis of the achieved result showed minor differences compared to preoperative planning. Surgical guides have the potential to improve the accuracy and predictability of genioplasty. The design should be further refined and the added value of the guides should be confirmed by means of prospective research.

Oxalobacter formigenes treatment confers protective effects in a rat model of primary hyperoxaluria by preventing renal calcium oxalate deposition.

In primary hyperoxaluria, increased hepatic oxalate production sometimes leads to severe nephrocalcinosis and early end-stage kidney disease. Oral administration of Oxalobacter formigenes (O. formigenes), an oxalate-degrading bacterium, is thought to derive oxalate from systemic sources by inducing net enteric oxalate secretion. Here, the impact of O. formigenes on nephrocalcinosis was investigated in an ethylene glycol rat model mimicking hepatic oxalate overproduction in primary hyperoxaluria. Eighteen rats were administered ethylene glycol (0.75% in drinking water) for 6 weeks, of which 9 were treated by oral gavage with O. formigenes and 9 received vehicle. Five control rats did not receive ethylene glycol or O. formigenes. Plasma and urinary oxalate levels, calcium oxalate crystalluria, urinary volume, fluid intake, and serum creatinine were monitored during the study. On killing, nephrocalcinosis was quantified. Ethylene glycol intake induced pronounced hyperoxalemia, hyperoxaluria, calcium oxalate crystalluria and nephrocalcinosis. Concomitant O. formigenes treatment partially prevented the ethylene glycol-induced increase in plasma oxalate and completely prevented nephrocalcinosis. Urinary oxalate excretion was not reduced by O. formigenes treatment. Nevertheless, absence of crystals in renal tissue of O. formigenes-treated ethylene glycol animals indicates that the propensity for oxalate to crystallize in the kidneys was reduced compared to non-treated animals. This is supported by the lower plasma oxalate concentrations in O. formigenes-treated animals. This study shows a beneficial effect of O. formigenes treatment on ethylene glycol-induced hyperoxalemia and nephrocalcinosis, and thus supports a possible beneficial effect of O. formigenes in primary hyperoxaluria.

Virtual occlusion in orthognathic surgery.

The aim of this retrospective study was to determine whether a virtually created occlusion is as accurate as a conventionally created occlusion. Seventeen orthognathic patients were included in the study, which was conducted in a university clinic. Plaster cast models were obtained and digitized. Two experienced observers created the conventional (gold standard) and virtual occlusion to assess inter-observer variability. One observer created the conventional and virtual occlusion a second time to assess the intra-observer variability. The criterion for accepting the virtual occlusion was that the difference between the gold standard and the virtual occlusion was not larger than the intra-observer variability for the gold standard. A non-parametric Kruskal-Wallis H test was performed to detect statistically significant differences between the intra- and inter-observer groups for both the conventional and virtual occlusion. No statistically significant differences were found between the different groups. The difference between the conventional and virtual occlusion group was 0.20mm larger than the intra-observer variability of the gold standard. The virtual occlusion tool presented here can be utilized in daily clinical practice and makes the use of physical dental models redundant.

[Innovations in dentistry. The influence of build angle on the fit of a 3D printed occlusal splint]. / Serie: Innovaties in de tandheelkunde. Het effect van printoriëntatie op de pasvorm van een 3D-geprinte occlusale wafer.

3D virtual planning optimises the predictability of orthognathic surgery. The planning is based on a cone beam computed tomography-scan of the patient as well as a plaster model, and is transferred to the patient by a 3D printed occlusal splint. In 3D printing the build angle influences, among other things, the accuracy (in earlier research, proven in dental crowns), manufacturing time and capacity. In this research, using 10 plaster models, 3 different build angles (0°, 30° and 90°) are compared. The fit of the splints was tested by 2 physicians using plaster models. According to this small sample, the fit does not depend on the build angle. When considering the manufacturing time and capacity, there is a preference for the 90º oriëntation, because it increases the manufacturing capacity and decreases the manufacturing time per splint.

Effect of skin tone on the accuracy of hybrid and passive stereophotogrammetry.

BACKGROUND: Three-dimensional (3D) surface images acquired from stereophotogrammetry are increasingly being used to plan or evaluate treatment by plastic surgeons. Stereophotogrammetry exists in active, passive, and hybrid forms. Active and hybrid stereophotogrammetry are believed to capture darker surfaces more accurately than passive stereophotogrammetry. The purpose of this study was to investigate whether skin tone has a clinically relevant effect on the accuracy of hybrid and passive stereophotogrammetry. MATERIALS AND METHODS: Seven subjects with different skin tones were recruited. 3D-printed face and breast were spray-painted in six different colors, ranging from white to black. The skin tones and paint colors were objectified by measuring their melanin index. 3D photos of the subjects and 3D prints were acquired with hybrid and passive stereophotogrammetry. These 3D photos were matched with specialized software, and their geometric differences were calculated. RESULTS: None of the 3D photos showed a clinically relevant mean inaccuracy. On the 3D prints, hybrid stereophotogrammetry resulted in a smaller standard deviation of the inaccuracies than passive stereophotogrammetry (0.20 ± 0.06 mm vs. 0.35 ± 0.07 mm, p < 0.001). Passive stereophotogrammetry yielded a correlation between the melanin index of the spray paint colors and the standard deviation of the inaccuracy (Pearson's R = 0.60, p = 0.04). On human subjects, no correlation or difference in standard deviation of the accuracy was found. CONCLUSION: Skin tone does not influence the accuracy of hybrid and passive 3D stereophotogrammetry in a clinically relevant way.

New software and breast boundary landmarks to calculate breast volumes from 3D surface images.

BACKGROUND: A method to accurately calculate breast volumes helps achieving a better breast surgery outcome. 3D surface imaging potentially allows these calculations in a harmless, quick, and practicable way. The calculated volume from a 3D surface image is dependent on the determined breast boundary and the method of chest wall simulation by software. Currently, there is no consensus on a robust set of breast boundary landmarks and validation studies on breast volume calculation software are scarce. The purposes of this study were to determine the robustness of newly introduced breast boundary landmarks and introduce and validate a new method to simulate a chest wall. METHODS: Sixteen subjects who underwent a unilateral simple mastectomy were included. In addition to the natural skin fold of the breast, the sternomanubrial joint, the transition of the pectoral muscle curve into the breast curvature, and the midaxillary line were used as landmarks to indicate the breast boundary. The intra- and interrater variability of these landmarks was tested. Furthermore, new chest wall simulation software was validated on the breastless chest side of the subjects. RESULTS: The intra- and interrater variability of the three breast boundary markers was small (mean 3.5-6.7 mm), and no significant difference was found between the intra- and interrater variability (p = 0.08, p = 0.06, and p = 0.10). The mean volume error of the most accurately simulated chest wall was 4.6 ± 37 ml. CONCLUSION: The newly introduced landmarks showed to be robust and our new chest wall simulation algorithm showed accurate results.Level of Evidence: Level IV, diagnostic study.

Accuracy and reproducibility of a newly developed tool for volume measurements of the arm using 3D stereophotogrammetry.

BACKGROUND: Lymph edema of the arm is a common complication after breast cancer treatment. To evaluate lymph edema volume and treatment outcome, an easy to use, objective quantification method of arm volume is necessary. Most often, water displacement is used to measure arm volume, as it is an easy and robust method that can be performed at any place with a simple equipment. However, when using water displacement, no exact localization of volume difference can be seen. To accurately measure hand and forearm volumes separately, an in-house-developed device was constructed for an accurate landmark placement. METHOD: An in-house developed measurement tool was used for placing artificial landmarks proximal to the wrist crease on ten healthy subjects. Three-dimensional (3D) images of the hand and forearm were acquired, and volume measurements of the hand and forearm were performed. Measurements were repeated to investigate the intra- and inter-rater variability caused by the landmark placement. RESULTS: Measuring volume of the hand and forearm while using artificially placed landmarks turned out to be a highly reproducible, quick, and easy procedure. Both intra- and inter-rater variability showed high reproducibility for hand (ICC = 0.96 and 0.98, respectively) and forearm (ICC = 0.99 and 0.99, respectively) volumes. CONCLUSION: Measuring volumes of the hand and forearm while using artificially placed landmarks was found to be a highly reproducible, quick, and easy procedure. The device enables to analyze the localization of lymph edema in greater details.

Potential impact of sitagliptin on collagen-derived dipeptides in diabetic osteoporosis.

It is known that diabetes coincides with an increased risk of osteoporosis. While a disturbed collagen metabolism is proposed as a possible cause, much remains unknown about the enzymes involved and changes in the collagen-derived dipeptides and amino acids. Therefore, we sought to study this intricate pathway and the effect of dipeptidyl peptidase 4 (DPP4) inhibitors. Control and streptozotocin-nicotinamide-induced diabetic rats were treated for 12 weeks with vehicle or sitagliptin, a DPP4 inhibitor (Con/VH, Con/SG, DM/VH and DM/SG). The activities of four key enzymes involved in collagen breakdown were determined in serum (DPP4, matrix metalloproteinase 2 and 9 and prolidase). Dipeptide (Ala-Pro, Gly-Pro, Pro-Pro and Pro-Hyp) and amino acid (Pro and Hyp) concentrations were measured by liquid chromatography coupled to mass spectrometry. We found three-fold higher MMP9 activities in DM/VH than in controls, while in DM/SG this rise was attenuated. MMP2 and prolidase did not differ in the investigated groups. Furthermore, we are the first to report on two-fold higher Ala-Pro and Pro-Pro levels in diabetes compared to controls. In contrast, Pro-Hyp concentrations were lower in diabetes (DM/VH and DM/SG). DPP4 inhibition does not seem to have a direct influence on the collagen metabolism in streptozotocin-nicotinamide-induced diabetic rats. Instead, it probably acts through its effect on osteoprotective substrates. In diabetes, increased MMP9 activities seem to favour the production of Ala-Pro and Pro-Pro containing collagen fragments. The high Pro-Hyp levels in untreated controls might have a bone-stimulating effect. Nevertheless, the biological significance of these dipeptides is not yet clear and should be further investigated.

Quantitative three-dimensional carrier mapping in nanowire-based transistors using scanning spreading resistance microscopy.

The performance of nanoelectronic devices critically depends on the distribution of charge carriers inside such structures. High-vacuum scanning spreading resistance microscopy (HV-SSRM) has established as the method of choice for quantitative 2D-carrier mapping in nanoscale devices during the last decade. However, due to the 3D-nature of these nanoscale device architectures, dopant incorporation and dopant diffusion mechanisms can vary for any of the three dimensions, depending on the particular processes used. Therefore, mapping of carriers in three dimensions with high spatial resolution is inevitable to study and understand the distribution of active dopants in confined 3D-volumes and ultimately to support the process development of next generation devices. In this work, we present for the first time an approach to extend the capabilities of SSRM from an inherent 2D-carrier profiling technique towards a quantitative 3D-characterization technique based on the example of a nanowire (NW)-based heterojunction (SiGe-Si) tunneling transistor. In order to implement a 3D-methodology with a 2D-imaging technique, we acquired 2D-carrier concentration maps on successive cross-section planes through the device of interest. This was facilitated by arranging several devices in a staggered array, allowing to produce a series of cross-sections with incremental offset by a single cleave. A dedicated interpolation algorithm especially suited for structures with rotational symmetry like NWs was developed in order to reconstruct a 3D-carrier distribution map. The validity of the method was assessed by proving the absence of variations in carrier distribution in the third dimension, as expected for NWs etched into a blanket stack.

Analysis of the lag phase to exponential growth transition by incorporating inoculum characteristics.

During the last decade, individual-based modelling (IbM) has proven to be a valuable tool for modelling and studying microbial dynamics. As each individual is considered as an independent entity with its own characteristics, IbM enables the study of microbial dynamics and the inherent variability and heterogeneity. IbM simulations and (single-cell) experimental research form the basis to unravel individual cell characteristics underlying population dynamics. In this study, the IbM framework MICRODIMS, i.e., MICRObial Dynamics Individual-based Model/Simulator, is used to investigate the system dynamics (with respect to the model and the system modelled). First, the impact of the time resolution on the simulation accuracy is discussed. Second, the effect of the inoculum state and size on emerging individual dynamics, such as individual mass, individual age and individual generation time distribution dynamics, is studied. The distributions of individual characteristics are more informative during the lag phase and the transition to the exponential growth phase than during the exponential phase. The first generation time distributions are strongly influenced by the inoculum state. All inocula with a pronounced heterogeneity, except the inocula starting from a uniform distribution, exhibit commonly observed microbial behaviour, like a more spread first generation time distribution compared to following generations and a fast stabilisation of biomass and age distributions.

Observation of diameter dependent carrier distribution in nanowire-based transistors.

The successful implementation of nanowire (NW) based field-effect transistors (FET) critically depends on quantitative information about the carrier distribution inside such devices. Therefore, we have developed a method based on high-vacuum scanning spreading resistance microscopy (HV-SSRM) which allows two-dimensional (2D) quantitative carrier profiling of fully integrated silicon NW-based tunnel-FETs (TFETs) with 2 nm spatial resolution. The key elements of our characterization procedure are optimized NW cleaving and polishing steps, the use of in-house fabricated ultra-sharp diamond tips, measurements in high vacuum and a dedicated quantification procedure accounting for the Schottky-like tip-sample contact affected by surface states. In the case of the implanted TFET source regions we find a strong NW diameter dependence of conformality, junction abruptness and gate overlap, quantitatively in agreement with process simulations. In contrast, the arsenic doped drain regions reveal an unexpected NW diameter dependent dopant deactivation. The observed lower drain doping for smaller diameters is reflected in the device characteristics by lower TFET off-currents, as measured experimentally and confirmed by device simulations.

Optimization of multi-walled carbon nanotube-metal contacts by electrical stressing.

We present experimental data on the contact resistances of three different metal probes, tungsten, palladium and indium, with chemical vapour deposited (CVD) multi-wall carbon nanotubes (MWCNTs). We demonstrate that there is an irreversible modification of the contacts following electrical stressing whereby the circuit resistance converges towards its optimal value prior to current-induced tube failure. Once the probe-MWCNT contact is broken, subsequent recontact experiments reveal that the circuit resistance returns to its initial high level, demonstrating that the modification occurs at the probe contact location and not elsewhere in the circuit. Contact studies with the different metals reveal that Pd metal provides the lowest resistance contact to the MWCNT in our sample.

Effect of pH, water activity and gel micro-structure, including oxygen profiles and rheological characterization, on the growth kinetics of Salmonella Typhimurium.

In this study, the growth of Salmonella Typhimurium in Tryptic Soy Broth was examined at different pH (4.50-5.50), water activity a(w) (0.970-0.992) and gelatin concentration (0%, 1% and 5% ) at 20 degrees C. Experiments in TSB with 0% gelatin were carried out in shaken erlenmeyers, in the weak 1% gelatin media in petri plates and in the firm 5% gelatin media in gel cassettes. A quantification of gel strength was performed by rheological measurements and the influence of oxygen supply on the growth of S. Typhimurium was investigated. pH, as well as a(w) as well as gelatin concentration had an influence on the growth rate. Both in broth and in gelatinized media, lowering pH or water activity caused a decrease of growth rate. In media with 1% gelatin a reduction of growth rate and maximal cell density was observed compared to broth at all conditions. However, the effects of decreasing pH and a(w) were less pronounced. A further increase in gelatin concentration to 5% gelatin caused a small or no additional drop of growth rate. The final oxygen concentration dropped from 5.5 ppm in stirred broth to anoxic values in petri plates, also when 0% and 5% gelatin media were tested in this recipient. Probably, not stirring the medium, which leads to anoxic conditions, has a more pronounced effect on the growth rate of S. Typhimurium then medium solidness. Finally, growth data were fitted with the primary model of Baranyi and Roberts [Baranyi, J. and Roberts, T. A., 1994. A dynamic approach to predicting bacterial growth in food. International Journal of Food Microbiology 23, 277-294]. An additional factor was introduced into the secondary model of Ross et al. [Ross, T. and Ratkowsky, D. A. and Mellefont, L. A. and McMeekin, T. A., 2003. Modelling the effects of temperature, water activity, pH and lactic acid concentration on the growth rate of Escherichia coli. International Journal of Food Microbiology 82, 33-43.] to incorporate the effect of gelatin concentration, next to the effect of pH and a(w). A two step and a global regression procedure were applied. Both procedures were able to fit the data well, but the global regression procedure led to smaller standard errors on the parameters.

Inactivation model equations and their associated parameter values obtained under static acid stress conditions cannot be used directly for predicting inactivation under dynamic conditions.

Organic acids (e.g., lactic acid, acetic acid and citric acid) are popular preservatives. In this study, the Listeria innocua inactivation is investigated under dynamic conditions of pH and undissociated lactic acid ([LaH]). A combined primary (Weibull-type) and secondary model developed for the L. innocua inactivation under static conditions [Janssen, M., Geeraerd, A.H., Cappuyns, A., Garcia-Gonzalez, L., Schockaert, G., Van Houteghem, N., Vereecken, K.M., Debevere, J., Devlieghere, F., Van Impe, J.F., 2007. Individual and combined effects of pH and lactic acid concentration on L. innocua inactivation: development of a predictive model and assessment of experimental variability. Applied and Environmental Microbiology 73(5), 1601-1611] was applied to predict the microbial inactivation under dynamic conditions. Because of its non-autonomous character, two approaches were proposed for the application of the Weibull-type model to dynamic conditions. The results quantitatively indicated that the L. innocua cell population was able to develop an induced acid stress resistance under dynamic conditions of pH and [LaH]. From a modeling point of view, it needs to be stressed that (i) inactivation model equations and associated parameter values, derived under static conditions, may not be suitable for use as such under dynamic conditions, and (ii) non-autonomous dynamic models reveal additional technical intricacies in comparison with autonomous models.

Proposed mechanisms in renal tubular crystal retention.

The production of concentrated urine inevitably leads to the precipitation of poorly soluble waste salts in the renal tubular fluid. These crystallization processes are physiologic and without consequences as long as all crystals are excreted with the urine. The retention of crystals in the renal tubules, however, may lead to tubular nephrocalcinosis. Here, we present a brief survey of the possible mechanisms involved in this process, which seems to depend predominantly on the presence of regenerating/(re)differentiating cells in the renal tubules. Crystal binding to the surface of these cells can be mediated by a number of luminal membrane molecules, including acidic fragment of nucleolin-related protein, annexin-II, osteopontin, and hyaluronan.

RelA regulates the survival of activated effector CD8 T cells.

Nuclear factor of kappa B (NF-kappaB) transcription factors are critical regulators of T-cell activation and survival. The relative contribution of individual NF-kappaB members to these processes remains elusive. We investigated the role of RelA in the regulation of CD8 T-cell activation. We overexpressed, in mature CD8 T cells, a transactivation domain-deficient RelA molecule (p65TAD). We show that p65TAD forms homo- and heterodimers with p50 that bind kappaB sites and selectively inhibit RelA-dependent transactivation. Expression of p65TAD does not affect initial activation or cell cycle progression but induces the death of activated CD8 T cells in vitro and in vivo. However, the long-term survival of resting effector CD8 T cells seems not to be affected by p65TAD expression. Collectively, our results indicate that RelA is a critical regulator of survival of proliferating CD8 T cells but may be dispensable for the survival of resting effector T cells.

Genotypes of Pestivirus RNA detected in anti-influenza virus vaccines for human use.

Nine polyvalent human influenza virus vaccines were tested by reverse transcriptase-polymerase chain reaction (RT-PCR) for the presence of pestivirus RNA. Samples were selected from manufacturers in Europe and the USA. Three samples of the nine vaccines tested (33.3%) gave positive results for pestivirus RNA. The 5'-untranslated genomic region sequence of the contaminant pestivirus RNA was analysed based on primary nucleotide sequence homology and on secondary sequence structures characteristic to genotypes. Two sequences belonged to Pestivirus type-1 (bovine viral diarrhoea virus [BVDV]) species, genotypes BVDV-1b and BVDV-1e. These findings confirm previous reports, suggesting an improvement in preventive measures against contamination of biological products for human use.