Bioprocess development of 2, 3-butanediol production using agro-industrial residues.

The valorization of agricultural and industrial wastes for fuel and chemical production benefits environmental sustainability. 2, 3-Butanediol (2,3-BDO) is a value-added platform chemical covering many industrial applications. Since the global market is increasing drastically, production rates have to increase. In order to replace the current petroleum-based 2,3-BDO production, renewable feedstock's ability has been studied for the past few decades. This study aims to find an improved bioprocess for producing 2,3-BDO from agricultural and industrial residues, consequently resulting in a low CO2 emission bioprocess. For this, screening of 13 different biomass samples for hydrolyzable sugars has been done. Alkali pretreatment has been performed with the processed biomass and enzyme hydrolysis performed using commercial cellulase. Among all biomass hydrolysate oat hull and spruce bark biomass could produce the maximum amount of total reducing sugars. Later oat hull and spruce bark biomass with maximum hydrolyzable sugars have been selected for submerged fermentation studies using Enterobacter cloacae SG1. After fermentation, 37.59 and 26.74 g/L of 2,3-BDO was obtained with oat hull and spruce bark biomass, respectively. The compositional analysis of each step of biomass processing has been performed and changes in each component have been evaluated. The compositional analysis has revealed that biomass composition has changed significantly after pretreatment and hydrolysis leading to a remarkable release of sugars which can be utilized by bacteria for 2,3-BDO production. The results have been found to be promising, showing the potential of waste biomass residues as a low-cost raw material for 2,3-BDO production and thus a new lead in an efficient waste management approach for less CO2 emission.

A Comparative Study of Pyrolysis Liquids by Slow Pyrolysis of Industrial Hemp Leaves, Hurds and Roots.

This study assessed the pyrolysis liquids obtained by slow pyrolysis of industrial hemp leaves, hurds, and roots. The liquids recovered between a pyrolysis temperature of 275-350 °C, at two condensation temperatures 130 °C and 70 °C, were analyzed. Aqueous and bio-oil pyrolysis liquids were produced and analyzed by proton nuclear magnetic resonance (NMR), gas chromatography-mass spectrometry (GC-MS), and atmospheric pressure photoionization Fourier transform ion cyclotron resonance mass spectrometry (APPI FT-ICR MS). NMR revealed quantitative concentrations of the most abundant compounds in the aqueous fractions and compound groups in the oily fractions. In the aqueous fractions, the concentration range of acetic acid was 50-241 gL-1, methanol 2-30 gL-1, propanoic acid 5-20 gL-1, and 1-hydroxybutan-2-one 2 gL-1. GC-MS was used to compare the compositions of the volatile compounds and APPI FT-ICR MS was utilized to determine the most abundant higher molecular weight compounds. The different obtained pyrolysis liquids (aqueous and oily) had various volatile and nonvolatile compounds such as acetic acid, 2,6-dimethoxyphenol, 2-methoxyphenol, and cannabidiol. This study provides a detailed understanding of the chemical composition of pyrolysis liquids from different parts of the industrial hemp plant and assesses their possible economic potential.

Polysomnographic scoring of sleep bruxism events is accurate even in the absence of video recording but unreliable with EMG-only setups.

PURPOSE: To determine the accuracy of scoring masticatory muscle activity (MMA) events in seven different polysomnography (PSG) setups. METHODS: Nineteen volunteers (13 females, 6 males, age 31.1 ± 12.9 years, 12 self-proclaimed bruxers) attended one-night PSG recording, supplemented with audio, video, and a separate frontal electroencephalography electrode set (FES). The same examiner scored the MMA events with seven different setups, with varying number of channels available: (1) one, (2) two, and (3) four EMG channels, (4) PSG without audio or video (PSG-N), (5) home PSG with FES and audio (FES-A), (6) PSG with audio (PSG-A), and (7) PSG with audio and video (PSG-AV). A subset (n = 10) of recordings was scored twice to determine intra-scorer reliability. MMA indices and accuracy of scoring the events in different setups were compared against PSG-AV. RESULTS: The intra-class correlation coefficient (ICC) between PSG-AV and PSG-A was high (0.940, p < 0.001) as well as for FES-A (0.927, p < 0.001), whereas for PSG-N, it was lower (0.835, p < 0.001); for setups with only EMG channels, coefficients were very low (ICC < 0.100 for all). Intra-examiner reliability was high (ICC > 0.939 for all setups), with the exception of PSG-N (ICC = 0.764, p = 0.002). When comparing against the MMA events scored in PSG-AV, the sensitivity of MMA event recognition for PSG-A was 78.5% and specificity 95.5%, which were substantially higher than sensitivity (52.0%) and specificity (87.2%) of PSG-N. CONCLUSIONS: MMA event scoring accuracy with PSG-A or FES-A is almost comparable to PSG-AV. Since precise event recognition is essential for accurate MMA scoring, it is evident that one cannot rely exclusively on EMG.

Classification of Wood Chips Using Electrical Impedance Spectroscopy and Machine Learning.

Wood chips are extensively utilised as raw material for the pulp and bio-fuel industry, and advanced material analyses may improve the processes in utilizing these products. Electrical impedance spectroscopy (EIS) combined with machine learning was used in order to analyse heartwood content of pine chips and bark content of birch chips. A novel electrode system integrated in a sampling container was developed for the testing using frequency range 42 Hz-5 MHz. Three electrode pairs were used to measure the samples in x-, y- and z-direction. Three machine learning methods were used: K-nearest neighbor (KNN), decision tree (DT) and support vector machines (SVM). The heartwood content of pine chips and bark content of birch chips were classified with an accuracy of 91% using EIS from pure materials combined with a k-nearest neighbour classifier. When using mixed materials and multiple classes, 73% correct classification for pine heartwood content (four groups) and 64% for birch bark content (five groups) were achieved.

Screen-printed ambulatory electrode set enables accurate diagnostics of sleep bruxism.

Currently, definite diagnosis of sleep bruxism requires polysomnography. However, it is restrictedly available, and too cumbersome and expensive for the purpose. The aim of this study was to introduce an ambulatory electrode set and evaluate its feasibility for more cost-effective diagnostics of sleep bruxism. Six self-assessed bruxers (one male, five females; aged 21-58 years) and six healthy controls (four males, two females, aged 21-25 years) underwent a standard polysomnographic study and a concurrent study with the ambulatory electrode set. Bruxism events, cortical arousals and sleep stages were scored for the two montages separately in a random order, and obtained sleep parameters were compared. In addition, the significance of video recording and sleep stage scoring for the diagnostic accuracy of ambulatory electrode set was determined. Ambulatory electrode set yielded similar diagnoses as standard polysomnography in all subjects. However, compared with standard polysomnography the median (interquartile range) tonic bruxism event index was significantly higher in the control group [+0.38 (+0.08 to +0.56) events per hour, P = 0.046], and the phasic bruxism event index was significantly lower in the bruxer group [-0.44 (-1.30 to +0.07) events per hour, P = 0.046]. Exclusion of video recording and both video recording and sleep stage scoring from analysis increased overestimation of the tonic bruxism event index in the control group +0.86 (+0.42 to +1.03) and +1.19 (+0.55 to +1.39) events per hour, P = 0.046 and P = 0.028, respectively], resulting in one misdiagnosed control subject. To conclude, ambulatory electrode set is a sensitive method for ambulatory diagnostics of sleep bruxism, and video recording and sleep stage scoring help reaching the highest specificity of sleep bruxism diagnostics.

Concentric Ring Probe for Bioimpedance Spectroscopic Measurements: Design and Ex Vivo Feasibility Testing on Pork Oral Tissues.

Many oral diseases, such as oral leukoplakia and erythroplakia, which have a high potential for malignant transformations, cause abnormal structural changes in the oral mucosa. These changes are clinically assessed by visual inspection and palpation despite their poor accuracy and subjective nature. We hypothesized that non-invasive bioimpedance spectroscopy (BIS) might be a viable option to improve the diagnostics of potentially malignant lesions. In this study, we aimed to design and optimize the measurement setup and to conduct feasibility testing on pork oral tissues. The contact pressure between a custom-made concentric ring probe and tissue was experimentally optimized. The effects of loading time and inter-electrode spacing on BIS spectra were also clarified. Tissue differentiation testing was performed for ex vivo pork oral tissues including palatinum, buccal mucosa, fat, and muscle tissue samples. We observed that the most reproducible results were obtained by using a loading weight of 200 g and a fixed time period under press, which was necessary to allow meaningful quantitative comparison. All studied tissues showed their own unique spectra, accompanied by significant differences in both impedance magnitude and phase (p ≤ 0.014, Kruskal-Wallis test). BIS shows promise, and further studies are warranted to clarify its potential to detect specific pathological tissue alterations.

Assessment of the suitability of using a forehead EEG electrode set and chin EMG electrodes for sleep staging in polysomnography.

Recently, a number of portable devices designed for full polysomnography at home have appeared. However, current scalp electrodes used for electroencephalograms are not practical for patient self-application. The aim of this study was to evaluate the suitability of recently introduced forehead electroencephalogram electrode set and supplementary chin electromyogram electrodes for sleep staging. From 31 subjects (10 male, 21 female; age 31.3 ± 11.8 years), sleep was recorded simultaneously with a forehead electroencephalogram electrode set and with a standard polysomnography setup consisting of six recommended electroencephalogram channels, two electrooculogram channels and chin electromyogram. Thereafter, two experienced specialists scored each recording twice, based on either standard polysomnography or forehead recordings. Sleep variables recorded with the forehead electroencephalogram electrode set and separate chin electromyogram electrodes were highly consistent with those obtained with the standard polysomnography. There were no statistically significant differences in total sleep time, sleep efficiency or sleep latencies. However, compared with the standard polysomnography, there was a significant increase in the amount of stage N1 and N2, and a significant reduction in stage N3 and rapid eye movement sleep. Overall, epoch-by-epoch agreement between the methods was 79.5%. Inter-scorer agreement for the forehead electroencephalogram was only slightly lower than that for standard polysomnography (76.1% versus 83.2%). Forehead electroencephalogram electrode set as supplemented with chin electromyogram electrodes may serve as a reliable and simple solution for recording total sleep time, and may be adequate for measuring sleep architecture. Because this electrode concept is well suited for patient's self-application, it may offer a significant advancement in home polysomnography.

Biomechanical evaluation of bone screw fixation with a novel bone cement.

BACKGROUND: Bone cement augmentation is commonly used to improve the fixation stability of orthopaedic implants in osteoporotic bone. The aim of this study was to evaluate the effect of novel bone cements on the stability of bone screw fixation by biomechanical testing and to compare them with a conventional Simplex(®)P bone cement and requirements of the standards. METHODS: Basic biomechanical properties were compared with standard tests. Adhesion of bone cements were tested with polished, glass blasted and corundum blasted stainless steel surfaces. Screw pullout testing with/without cement was carried out using a synthetic bone model and cancellous and cortical bone screws. RESULTS: All the tested bone cements fulfilled the requirements of the standard for biomechanical properties and improved the screw fixation stability. Even a threefold increase in shear and tensile strength was achieved with increasing surface roughness. The augmentation improved the screw pullout force compared to fixation without augmentation, 1.2-5.7 times depending on the cement and the screw type. The good biomechanical properties of novel bone cement for osteoporotic bone were confirmed by experimental testing. CONCLUSION: Medium viscosity of the bone cements allowed easy handling and well-controlled penetration of bone cement into osteoporotic bone. By proper parameters and procedures it is possible to achieve biomechanically stable fixation in osteoporotic bone. Based on this study, novel biostable bone cements are very potential biomaterials to enhance bone screw fixation in osteoporotic bone. Novel bone cement is easy to use without hand mixing using a dual syringe and thus makes it possibility to use it as required during the operation.

A Handy EEG Electrode Set for patients suffering from altered mental state.

Although electroencephalography (EEG) is an important diagnostic tool for investigating patients with unexplained altered mental state (AMS), recording of emergency EEG is not a clinical routine. This is mainly due to the cumbersome electrode solutions. A Handy EEG Electrode Set consists of ten EEG, two EOG, two ground and two commutative reference hydrogel-coated silver wire electrodes attached to a thin polyester carrier film. The clinical usefulness of the Handy EEG Electrode Set was tested in 13 patients (five females, eight males) with AMS. EEG recordings were conducted at the same time with a standard 10-20 electrode set. The registration in the first patient case without the behind-ear electrodes (T9 and T10), indicated that these electrodes are very crucial to provide clinically relevant information from posterior regions of brain. In following 12 cases, the sensitivity and specificity for detecting EEG abnormality based on the Handy EEG Electrode Set recordings were 83 and 100 %, respectively. The Handy EEG Electrode Set proved to be easy to use and to provide valuable information for the neurophysiological evaluation of a patient suffering from AMS. However, further studies with larger number of patients are warranted to clarify the true diagnostic accuracy and applicability of this approach.

Accuracy of Dental Restorations Fabricated Using Milling vs 3D-Printed Molds: A Pilot Study.

PURPOSE: To compare the accuracy of 12 different dental restorations fabricated with milling or 3D-printed molds and robotically controlled casting. MATERIALS AND METHODS: Twelve dental restorations (11 inlays and onlays and 1 crown) were made per restoration type, one per each of the 12 different teeth models (total of 24 restorations). On each tooth preparation, two restorations were manufactured using different CAD/ CAM techniques: (1) milling and (2) robotically controlled casting and 3D-printed molds. In addition, twolayer restorations were manufactured with 3D-printed molds. The marginal and internal gaps were evaluated at 120 points per restoration based on micro-CT 3D imaging. Internal gaps were evaluated using a replica technique with silicone. RESULTS: Median values (interquartile ranges) for marginal gaps, middle internal gaps, and central internal gaps were significantly lower for 3D-printed mold restorations (44.3 [65.4] µm, 95.4 [96.2] µm, and 104.6 [78.1] µm) compared to milled restorations (58.4 [93] µm, 145.9 [85.8] µm, and 138.6 [65.7] µm). Internal gaps in the 3D-printed mold group were 6% to 51% smaller than in the milled group. CONCLUSIONS: The accuracy of restorations fabricated with 3D-printed molds may be preferable compared to milled restorations, except in the case of crown restoration. However, additional studies with a larger number of samples and different types of restorations are needed to confirm the results.

[Nanoscale tailoring of the surface properties of biomaterials and drug carriers]. / Nanoteknologia biomateriaalien ja lääkkeiden kantaja-aineiden pintojen räätälöinnissä.

Functionalities of biomaterials and drug delivery systems are improved by tailoring their surface properties using modern nanotechnology. Orthopedic implants and invasive electrodes are examples of implantable biomaterials. Biological interactions of orthopedic implants can be optimized by the synergetic effect of surface micro- and nanotexturing with a chemical composition of coating. Further, mechanical flexibility and electrochemical characteristics of invasive electrodes are improved by using micro- and nanotechnology. In nano-size drug delivery systems, surface properties of nanocarriers strongly affect their safety and efficacy. Mesoporous silicon nanoparticles are example of nanocarriers those properties can be tailored for drug delivery applications.

In vitro adhesion of staphylococci to diamond-like carbon polymer hybrids under dynamic flow conditions.

This study compares the ability of selected materials to inhibit adhesion of two bacterial strains commonly implicated in implant-related infections. These two strains are Staphylococcus aureus (S-15981) and Staphylococcus epidermidis (ATCC 35984). In experiments we tested six different materials, three conventional implant metals: titanium, tantalum and chromium, and three diamond-like carbon (DLC) coatings: DLC, DLC-polydimethylsiloxane hybrid (DLC-PDMS-h) and DLC-polytetrafluoroethylene hybrid (DLC-PTFE-h) coatings. DLC coating represents extremely hard material whereas DLC hybrids represent novel nanocomposite coatings. The two DLC polymer hybrid films were chosen for testing due to their hardness, corrosion resistance and extremely good non-stick (hydrophobic and oleophobic) properties. Bacterial adhesion assay tests were performed under dynamic flow conditions by using parallel plate flow chambers (PPFC). The results show that adhesion of S. aureus to DLC-PTFE-h and to tantalum was significantly (P < 0.05) lower than to DLC-PDMS-h (0.671 ± 0.001 × 10(7)/cm(2) and 0.751 ± 0.002 × 10(7)/cm(2) vs. 1.055 ± 0.002 × 10(7)/cm(2), respectively). No significant differences were detected between other tested materials. Hence DLC-PTFE-h coating showed as low susceptibility to S. aureus adhesion as all the tested conventional implant metals. The adherence of S. epidermidis to biomaterials was not significantly (P < 0.05) different between the materials tested. This suggests that DLC-PTFE-h films could be used as a biomaterial coating without increasing the risk of implant-related infections.

Early bone growth on the surface of titanium implants in rat femur is enhanced by an amorphous diamond coating.

BACKGROUND AND PURPOSE: Amorphous diamond (AD) is a durable and compatible biomaterial for joint prostheses. Knowledge regarding bone growth on AD-coated implants and their early-stage osseointegration is poor. We investigated bone growth on AD-coated cementless intramedullary implants implanted in rats. Titanium was chosen as a reference due to its well-known performance. MATERIALS AND METHODS: We placed AD-coated and non-coated titanium implants (R(a) ≈ 0.2 µm) into the femoral bone marrow of 25 rats. The animals were divided in 2 groups according to implant coating and they were killed after 4 or 12 weeks. The osseointegration of the implants was examined from hard tissue specimens by measuring the new bone formation on their surface. RESULTS: 4 weeks after the operation, the thickness of new bone in the AD-coated group was greater than that in the non-coated group (15.3 (SD 7.1) µm vs. 7.6 (SD 6.0) µm). 12 weeks after the operation, the thickness of new bone was similar in the non-coated group and in the AD-coated group. INTERPRETATION: We conclude that AD coating of femoral implants can enhance bone ongrowth in rats in the acute, early stage after the operation and might be an improvement over earlier coatings.

The effect of loading and material on the biomechanical properties and vitality of bovine cartilage in vitro.

PURPOSE: New methodology for long-term (270 h) biomechanical testing with living cartilage was developed. Polyurethane (PU) implant material was compared with stainless steel and reference samples in static unconfined compressive loading conditions on cartilage to provide a basis for dynamic testing of novel PU implant materials under conditions that simulate an articulating human knee joint. METHODS: Custom-made tools and techniques were developed to prepare cylindrical samples from bovine patella with cartilage including subchondral bone. Specific incubator cups with static loading setups for a culture incubator were manufactured to keep bovine cartilage explants alive in cell culture conditions under unconfined static compressive loading (0.25 MPa) for 270 h (11.25 d). Four loading conditions of cartilage were studied: free (FREE), restrained minimal loading (RESTR), loading with a metal plate (MEW) and loading with polyurethane (PUW). RESULTS: After static loading for 270 h, cartilage biomechanical tests indicated clear differences between the groups in frequency dependent dynamic stiffness curves. Surprisingly, the PU curves were closest to the FREE sample curves. Those with load and direct contact with metal (MEW) became significantly stiffer, while restrained samples became softer. Significant differences (p<0.05, Mann-Whitney's U test) in cell vitality between samples from various groups could be seen in fluorescein diacetate (FDA) and propidium iodide (PI) stained samples by confocal microscopic analysis. The approximate mean percentages of living cells after 270 hours cultivation were: FREE 87%, MEW 3%, PUW 35%, and RESTR 66%. Test results indicate that it is possible to keep cartilage cells alive in cell culture incubator conditions for two weeks period under a 0.25 MPa unconfined static loading. The FREE samples were most successful and cells loaded with PU were more vital than cells loaded with metal. CONCLUSIONS: Based on the results, PU seems to be more compatible material than surgical steel in contact with living cartilage. Because of a large variation in the quality of bovine cartilage material from different animals, special care is necessary when selecting specimens to guarantee reliable and reproducible results.

Bio-based wood preservatives: Their efficiency, leaching and ecotoxicity compared to a commercial wood preservative.

Companies in the wood industry are constantly developing their outdoor products. The possibility of using bio-based chemicals as an alternative to traditional wood preservatives-regulated in Europe by The Biocidal Products Regulation No 528/2012-has been considered, but chemical leaching from the wood decreases its effectiveness and may negatively affect the environment. This study aims to compare the effectiveness of bio-based chemicals with potential use in wood preservation to commercially available preservatives, to investigate their fixation to wood and their ecotoxicity and to quantify the potentially toxic elements leached from the wood. Pyrolysis distillates of tree bark, organic acids found in distillates, Colatan GT10 tannin extract and log soaking liquid as a hardwood veneer process residue were tested and compared with commercial pine oil and a copper-based wood preservative. In the wood decay test of impregnated pine sapwood specimens, Colatan GT10 extract performed as well as the commercial wood preservatives. The same decay trial with leached specimens significantly reduced the performance of the bio-based chemicals. The results of the ecotoxicity test with photoluminescent Aliivibrio fischeri bacteria showed that many bio-based chemicals with potential use in wood preservation have markedly lower ecotoxicity than commercially available wood preservatives, but the ecotoxicity of some bio-based chemicals is higher, as in the case of some of the pyrolysis distillates. The wood preservation efficiency and the ecotoxicity of the studied chemicals had a poor correlation, implying that other factors besides treatment agent toxicity play a role in deterring fungal growth on treated wood. The amount of elemental toxins in the leachates was low. These results emphasize the importance of the chemical ecotoxicity of bio-based preservative compounds, as their detrimental effect on the environment can be higher than that of the traditional preservatives unless effectively linked to wood to prevent leaching.

Low-Dose Doxycycline Treatment Normalizes Levels of Some Salivary Metabolites Associated with Oral Microbiota in Patients with Primary Sjögren's Syndrome.

Saliva is a complex oral fluid, and plays a major role in oral health. Primary Sjögren's syndrome (pSS), as an autoimmune disease that typically causes hyposalivation. In the present study, salivary metabolites were studied from stimulated saliva samples (n = 15) of female patients with pSS in a group treated with low-dose doxycycline (LDD), saliva samples (n = 10) of non-treated female patients with pSS, and saliva samples (n = 14) of healthy age-matched females as controls. Saliva samples were analyzed with liquid chromatography mass spectrometry (LC-MS) based on the non-targeted metabolomics method. The saliva metabolite profile differed between pSS patients and the healthy control (HC). In the pSS patients, the LDD treatment normalized saliva levels of several metabolites, including tyrosine glutamine dipeptide, phenylalanine isoleucine dipeptide, valine leucine dipeptide, phenylalanine, pantothenic acid (vitamin B5), urocanic acid, and salivary lipid cholesteryl palmitic acid (CE 16:0), to levels seen in the saliva samples of the HC. In conclusion, the data showed that pSS is associated with an altered saliva metabolite profile compared to the HC and that the LLD treatment normalized levels of several metabolites associated with dysbiosis of oral microbiota in pSS patients. The role of the saliva metabolome in pSS pathology needs to be further studied to clarify if saliva metabolite levels can be used to predict or monitor the progress and treatment of pSS.

Enhancement of silicon using micro-patterned surfaces of thin films.

Micro-textured biomaterials might enhance cytocompatibility of silicon-based micro-electro-mechanical system (bio-MEMS) dummies. Photolithography-physical vapour deposition was used to produce diamond-like carbon (DLC) or Ti squares and circles on silicon, and also their inverse replicas; then DLC and Ti were compared for their guiding potential, using a SaOS-2 cell model. Scanning electron microscopy at 48 hours indicated cells were well-spread on large-sized patterns (several cells on one pattern) and assumed the geometrical architecture of underlying features. Medium-sized patterns (slightly smaller than solitary indicator cells) were inhabited by singular cells, which stretched from one island to another, assuming longitudinal or branching morphologies. On small-sized patterns (much smaller than individual cells;rpar; cells covered large micro-textured areas, but cellular filopodia bypassed the bare silicon. Immunofluorescence and confocal laser scanning microscopy indicated that the actin cytoskeleton and vinculin-containing adhesion junctions were present on the patterned areas, but not on the bare silicon. Cell density/coverage disclosed a 3.4-3.7-fold preference for the biomaterial patterns over silicon substrate (p 0.001). Differences in the cellular response between materials were lost at 120 hours when cells were confluent. The working hypothesis was proven; enhancement by micro-patterning depends on the pattern size, shape and material and can be used to improve biocompatibility during the initial integration phase of the device.

Adhesion, spreading and osteogenic differentiation of mesenchymal stem cells cultured on micropatterned amorphous diamond, titanium, tantalum and chromium coatings on silicon.

It was hypothesized that human mesenchymal stromal cell (hMSC) can be guided by patterned and plain amorphous diamond (AD), titanium (Ti), tantalum (Ta) and chromium (Cr) coatings, produced on silicon wafer using physical vapour deposition and photolithography. At 7.5 h hMSCs density was 3.0-3.5 x higher (P < 0.0003, except Ti) and cells were smaller (68 vs. 102 microm, P 0.000006-0.02) on patterns than on silicon background. HMSC-covered surface of the background silicon was lower on Ti than AD patterns (P = 0.015), but at 5 days this had reversed (P = 0.006). At 7.5 h focal vinculin adhesions and actin cytoskeleton were outgoing from pattern edges so cells assumed geometric square shapes. Patterns allowed induced osteogenesis, but less effectively than plain surfaces, except for AD, which could be used to avoid osseointegration. All these biomaterial patterns exert direct early, intermediate and late guidance on hMSCs and osteogenic differentiation, but indirect interactions exist with cells on silicon background.

Novel 3D printing-based probe for impedance spectroscopic examination of oral mucosa: design and preliminary testing with phantom models.

The diagnosis of oral potentially malignant disorders currently relies on histopathological examination of surgically removed biopsies causing pain and discomfort for the patient. We hypothesise that non-invasive bioimpedance spectroscopy (BIS) method would overcome these problems and could make possible regular screening of at-risk patients. Previously several hand-made probes have been introduced in such BIS studies. However, for the first time, we aimed to design a 3D printed probe and test it with model samples (saline solutions, cucumber and porcine tongue). We found that it is extremely crucial to select proper printable materials and optimise electrode geometries to avoid electrochemical corrosion problems, short-circuiting and other signal instabilities related to miniaturised probe. However, our final prototype constructed with four high purity silver made electrodes showed a good linearity (R 2 = 0.999) in diluted saline solution measurements over a wide conductivity range (0.25‒8 mS/cm), which covers well the range of values for the different biological tissues. Moreover, our data show that high reproducibility of the manufacturing and measurement is one important merit in the present 3D printed probe. However, further studies are needed to clarify the importance of fixed pressure especially when the tetrapolar 3D printed probe is used as a hand-held apparatus.

Variability of salivary metabolite levels in patients with Sjögren's syndrome.

PURPOSE: To investigate inter- and intra-individual variation in the levels and outputs (concentration multiplied by salivary flow rate) of salivary metabolites in patients with primary Sjögren's syndrome (pSS). METHODS: A total of 56 samples of stimulated saliva were collected from 14 female pSS patients during four laboratory visits within 20 weeks and analyzed using proton nuclear magnetic resonance spectroscopy. Single saliva samples from each of 15 controls were also analyzed. RESULTS: Among 21 quantified metabolites, choline was significantly elevated in the pSS patients at each time point (P ≤ 0.015), taurine at the last three time points (P ≤ 0.013), alanine at the last two time points (P ≤ 0.007) and glycine at the last time point (P = 0.005). Inter-individual variation in metabolite concentrations was generally larger among the patients than among the controls, and significantly large variations were observed for glycine (P ≤ 0.007, all time points), choline (P ≤ 0.033, three last time points) and alanine (P = 0.028, baseline). Metabolite output analysis showed that choline had the lowest intra-patient variation. CONCLUSION: In spite of considerable intra- and inter-individual variation, levels and outputs of specific metabolites in patients with pSS differ from those in controls, and may be potentially applicable as new biological markers for monitoring of the response to treatment.