[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.

[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.

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.

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.

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.

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.

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.

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.

Expression of H-2Db on the cell surface in the absence of detectable beta 2 microglobulin.

In this report we describe a variant of the C57BL/6 T lymphoma EL4 (EL4/Mar) which, in contrast to the parental cell line, expresses neither H-2Kb nor beta2-microglobulin (beta2m) but which does express H-2Db detectable by serology and by alloreactive cytotoxic T lymphocytes (CTL). This observation raises the possibility that H-2Db and perhaps other major histocompatibility complex class I molecules are normally not associated with beta2m on the cell surface. In addition, this report is the first to indicated that alloreactive CTL can interact with a beta2m-free class I antigen.

Multiple H-2 linked immune response gene control of H-2 D-associated T-cell-mediated lympholysis to trinitrophenyl-modified autologous cells: Ir-like genes mapping to the left of I-A and within the I region.

One of the more recent associations of the murine H-2 major histocompatibility complex (MHC) with immune function has been the finding that cytotoxic T-effector cells generated by sensitization with viral-infected (1-6), chemically modified (7-9), or weak transplantation antigen-associated (10,11) syngeneic cells can efficiently lyse target cells which express the same viral, chemical, or weak antigenic agent, and which share the H-2K and/or H-2D regions of the MHC with the responding and/or stimulating cells. Furthermore, an additional contribution of a gene(s) within the H-2 complex has been demonstrated which controls immune response potential (Ir genes) in the generation of cytotoxic effector cells to trinitrophenyl (TNP)-modified self components (12,13). In such studies it was found that certain B10 congenic strains generated good cytotoxic responses to both TNP- modified H-2K and H-2D region products, whereas other B10 congenic strains exhibited preferential or exclusive reactivity against TNP-modified H-2K region products. Some of these recombinant strains differing in response potential to TNP- modified H-2D products expressed the same haplotype at the D end, but differed at the K end of H-2. The low responsiveness observed in the B10.A strain to TNP-modified H-2D(d) when compared to B10.D2 and (B10.A x B10.D2)F(1) for the same specificity, suggested a role of dominant Ir genes which map in K, I-A, I-B, I-J, and/or I-E (12, 14). In the present report an attemnpt was made to further map within the MHC the Ir gene(s) controlling cell-mediated lympholysis (CML) to TNP-modified H-2D(d), by using recombinant mouse strains on the A and B10 backgrounds. Irrespective of the genetic background, the s and k haplotypes at the K end generated high and low cytotoxic responses, respectively, to H-2D(d)-TNP. The intermediate responder and low responder status of the A.TL and A.AL strains, respectively, indicated that a gene mapping in the K region of H-2 influences response potential. Furthermore, the differences in the levels of cytotoxicity detected in the A.TH and A.TL strains suggested an additional I region influence. Taken together these findings raise the possibility that multiple genes mapping within different regions of the MHC control the level of T-cell-mediated cytotoxicity to chemically modified autologous cells.

Bifunctional major histocompatibility-linked genetic regulation of cell-mediated lympholysis to trinitrophenyl-modified autologous lymphocytes.

Murine thymus-derived lymphocytes can be sensitized in vitro to trinitrophenyl (TNP)-modified autologous spleen cells (1, 2). Cytotoxic effector cells were generated which were specific for TNP-modified target cells expressing the same H-2K and H-2D serological regions as the modified stimulator cells (3, 7). Spleen cells from two C57BL/10 congenic strains of mice sharing common I-C, S, and D regions, but differing at K, I-A, and I-B regions, generated different levels of lytic responses to the shared modified H-2Dd products upon sensitization with auto logous TNP-modified cells. Lymphocytes from an F1 between responder and nonresponder strain generated a level of cytolysis toward the H-2Dd modified specificity which was of the same order of magnitude as that obtained with the high responder, irrespective of whether F 1 or either parental strain of modified stimulator cell was used. These results suggest that the modification of H-2Dd products resulted in formation of new antigenic determinants in both parental strains. However, the difference observed in responsiveness appeared to be due to a gene or genes mapping in the K, I-A, or I-B region which influenced the ability of the responding lymphocytes to react to these modified H-2Dd products. Responsiveness was expressed as a dominant trait in the F1.

Cell-mediated lympholysis of trinitrophenyl-modified autologous lymphocytes. Confirmation of genetic control of response to trinitrophenyl-modified H-2 antigens by the use of anti-H-2 and anti-Ia antibodies.

Splenic lymphocytes from B10.A and B10.D2 mice were sensitized in vitro to trinitrophenyl (TNP)-modified autologous spleen cells. The effector cells generated were assayed in a 51Cr-release assay on TNP-modified syngeneic or congenic spleen target cells. Effector cells from B10.A donors lysed TNP-modified H-2Kk- but not H-2Dd-region products, whereas B10.D2 effectors reacted with modified products of both the H-2Kd and H-2Dd regions. As an independent confirmation that this selective K-end lysis by B10.A effector cells is due to an H-2-linked responder cell defect (4), anti-H-2Kk but not anti-H-2Dd sera were shown to inhibit the lysis of B10.A-TNP targets by B10.A effectors. In contrast, anti-H-2Dd sera inhibited the lysis of B10.A-TNP targets by B10.D2 effectors. Anti-Ia antibodies had no detectable effect on lysis. Anti-TNP-keyhole limpet hemocyanin sera blocked the lysis of TNP-modified targets, irrespective of whether the effector cells were directed against TNP-modified autologous H-2 products or H-2 alloantigens. These results independently verify that B10. A responding lymphocytes do not generate effector cells to TNP-modified H-2Dd products, whereas B10.D2 lymphocytes do (4), and suggest that some TNP groups are sterically close to (or part of) the serologically defined H-2K- and H-2D-region antigens.

Mixed lymphocyte reactivity and cell-mediated lympholysis to trinitrophenyl-modified autologous lymphocytes in C57BL/10 congenic and B10-A recombinant mouse strains.

Cell-mediated lympholysis (CML) to trinitrophenyl (TNP)-modified autologous splenic lymphocytes has been recently reported in the mouse (1). Both the sensitization and effector phases of this phenomenon were shown to be T-cell mediated. Effector cell specificity studies indicated that modification of the target cells is a necessary but insufficient requirement for cytolysis, and suggested that altered cell surface components controlled by genes mapping in the mouse major histocompatibility H-2 complex (MHC) are important in the specificity of the cytotoxic reaction (1). In allogeneic models the generation of cytotoxic effector cells has been shown to be preceded or accompanied by immunogen- induced proliferation of responding lymphocytes, i.e. a mixed lymphocyte reaction (MLR) (2-5), although the generation of effectors may not necessarily always be the consequence of extensive cell proliferation (5). If the induction of cytotoxic effector lymphocytes by modified syngeneic spleen cells is characteristic of sensitization with cellular alloantigens, one would expect to find that sensitization with TNP-modified autologous cells would also induce thymidine incorporation by the responding cells in the culture. The present report demonstrates that both stimulation of thymidine incorporation and generation of cytotoxic effector cells are part of the in vitro response to TNP-modified autologous lymphocytes. However, the MLR to TNP- modified autologous cells consistently appeared to be less pronounced when compared with an allogeneic MLR, whereas the cytotoxic activity of the effector cells generated by sensitization against TNP-modified autologous cells was frequently as high as that detected against H-2 alloantigens. These two components of reactivity to "modified self" are verified in several C57BL/10 congenic and B10.A recombinant mouse strains.

H-2-linked genetic control of murine T-cell-mediated lympholysis to autologous cells modified with low concentrations of trinitrobenzene sulfonate.

Spleen cells from B10.BR and C57BL/10 (B10) mice were compared for their ability to generate primary in vitro cytotoxic responses to syngeneic cells modified with different concentrations (from 10 to 0.031 mM) of trinitrobenzene sulfonate (TNBS) (TNP-self). Although both strains generated effector cells to TNP-self in the range of 10-0.25 mM TNBS modification, effector activity of B10 cells was weaker than that of B10.BR cells. B10 spleen cells did not respond to syngeneic stimulating cells modified at 0.1 mM or lower, whereas B10.BR cells generated effector activity even when stimulated by TNP-self modified with as low as 0.031 mM TNBS. Fluorescence analysis of the modified cells using the FACS II indicated that equivalent quantities of TNP were conjugated to the surfaces of B10.BR and B10 spleen cells for any given concentration of TNBS modification. Similar strain-dependent differences were observed when the TNP was diluted out in the cultures by reducing the number of stimulating cells modified with 10 mM TNBS. These response patterns were verified by stimulating cultures of B10.BR and B10 spleen cells either with TNP conjugated to bovine serum albumin or bovine gamma globulin (B10.BR but not B10 cells responded to TNP-conjugated proteins) or with TNBS-modified glass-adherent spleen cells. The strain-dependent differences could also be detected at the effector phase, because optimally stimulated B10.BR, but not B10 effector cells, could lyse 0.1 mM TNBS-modified syngeneic target cells. The genetic parameters associated with the response and nonresponse patterns of B10.BR and B10 mice were further investigated by comparing the cytotoxic responses to low doses of TNP-self of spleen cells from the following strains: (a) C3H/HeJ (H-2k) and C3H.SW (H-2b); (b) BALB.K (H-2k) and BALb.b (h-2b); and (c) B10.A (H-2a) and B10.D2 (H-2d). The H-2k and H-2a, but not the H-2b and H-2d, strains generated cytotoxic responses to TNP-self when the syngeneic stimulators were modified with 0.1 mM TNBS. Further studies using (B10 X B10.BR)F1 responding cells and parental or F1-modified stimulating cells, indicated that the F1 cells generated cytotoxic activity to low doses of TNP in association with H-2k but not in association with H-2b self products. The results of this study indicate that H-2-linked genetic factors, expressed in the target as well as in the responding and/or stimulating cell populations, control the ability of inbred mouse strains to generate cytotoxic effector cells to low doses of TNP-self. Such dose-dependent genetic effects may be important in the regulation of immune responses activated in vivo by chronic exposure to infectious agents.

H-2-restricted cytotoxic effectors generated in vitro by the addition of trinitrophenyl-conjugated soluble proteins.

Murine spleen cells from normal donors were cultured in vitro with trinitrobenzene sulfonate (TNBS)-conjugated soluble proteins, i.e., bovine gamma globulin (TNP-BGG) or bovine serum albumin (TNP-BSA). Addition of 100 mug of any of these TNP-proteins to the spleen cell cultures led to the generation of cytotoxic T-cell effectors which were H-2-restricted and TNP- specific. The lytic potential of such effectors was comparable to that generated by sensitization with TNBS-modified syngeneic cells, and was restricted to haplotypes shared at the K or K plus I-A, or the D regions of the H-2 complex. Greater effecter cell activity was generated by addition of TNP-BGG against TNBS-modified targets which shared K plus I-A than against modified targets which shared the D region with the responding cells, which suggests that the same immune response genes are involved when the response is generated by the addition of TNP-conjugated soluble proteins or of TNBS- modified cells. H-2-restricted, TNP-specific effecter cells were generated by culturing mouse spleen cells with syngeneic cells which had been preincubated with TNP- BGG or TNP-BSA for 1.5 h. The addition of unconjugated soluble proteins to the cultures did not result in cytotoxic effectors detectable on H-2-matched targets, whether the targets were prepared by modification with TNBS, or by incubation with either the unconjugated or TNP-conjugated proteins. Depletion of phagocytic cells in the tumor preparation by Sephadex G-10 column fractionation before incubation with TNP-BSA had no effect on their lysis by the relevant effector cells. Immunofluorescent staining of tumor target cells with anti-TNP antibodies indicated that TNP could be detected on the tumor cells within 10 rain of incubation with TNP-BSA. The cytotoxic response generated by addition of the TNP-proteins to spleen cell cultures was found to be T-cell dependent at the effector phase, as shown by the sensitivity of the lytic phase to absorbed RAMB and complement. Furthermore, the response did not appear to be attributable to antibody-dependent cellular cytotoxicity. Three mechanisms were considered which could account for the generation of H-2-restricted, TNP-specific, cytotoxic T-cell effectors by the addition of soluble TNP-proteins. These include covalent linkage of activated TNP groups from the soluble proteins to cell surface components, macrophage processing of the soluble conjugates and presentation to the responding lymphocytes in association with H-2-coded self structures, or hydrophobic interaction of the TNP-proteins to cell surfaces. Results obtained from sodium dodecyl sulfate gel patterns indicating that cell-bound TNP was still linked to BSA, and the observation that phagocytic-depleted cells could interact with the soluble TNP-proteins and function as H-2-restricted targets, appear not to favor the first two proposed mechanisms.

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 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.

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.