Accuracy of inlay and onlay restorations based on 3D printing or milling technique - a pilot study

PURPOSE

To evaluate and compare the accuracy of 3D printing versus CAD/CAM milling in the fabrication of inlay/onlay restorations based on pilot experiments.

MATERIAL AND METHODS

Different shaped inlay/onlay cavities were prepared on six extracted and root canal treated human molar teeth. Digital impressions were taken with a CEREC AC Omnicam© intraoral scanner. Based on the same impression data, nano-ceramic restorations were performed using milling (M group) and composite restorations (from material not for clinical use) using Multijet 3D printing technology (3D group). The accuracy was evaluated by measuring the marginal and internal gaps based on x-ray microtomography 3D imaging scans. The internal fit was evaluated using a replica technique with A-silicone impressions and weighing.

RESULTS

The 3D group restorations showed better marginal and internal fit values. The mean internal gap values of the 3D group restorations were 40-60% lower compared to the M group restorations, the difference being statistically significant at most measuring points (p⟨0.05, t-test).

CONCLUSIONS

The accuracy of the Multijet 3D printing is at least at the same level as the milling technique in the fabrication of dental inlay/onlay restorations. Additional investigations are needed to develop the 3D printing process and suitable materials for dental applications.

Salivary metabolomics in the diagnosis of oral cancer and periodontal diseases

Metabolomics is a systemic study of metabolites, which are small molecules generated by the process of metabolism. The metabolic profile of saliva can provide an early outlook of the changes associated with a wide range of diseases, including oral cancer and periodontal diseases. It is possible to measure levels of disease-specific metabolites using different methods as presented in this study. However, many challenges exist including incomplete understanding of the complicated metabolic pathways of different oral diseases. The review concludes with the discussion on future perspectives of salivary metabolomics from a clinician point of view. Salivary metabolomics may afford a new research avenue to identify local and systemic disorders but also to aid in the design and modification of therapies. A MEDLINE search using keywords "salivary metabolomics" returned 23 results in total, of which seven were omitted for being reviews or letters to the editor. The rest of the articles were used for preparation of the review, 13 of these were published in the last 5 years.

Spectroscopy in the analysis of bacterial and eukaryotic cell footprints on implant surfaces

We tested the suitability of two spectroscopic methods, x-ray photoelectron spectroscopy (XPS) and time of flight secondary ion mass spectrometry (ToF-SIMS), in the recognition of bacterial and eukaryotic cell footprints on implant surfaces. Human mesenchymal stem cells (MSCs) and Staphylococcus aureus were cultured on sample surfaces and detached using trypsin. Scanning electron microscopy confirmed that the processed surfaces did not contain any human or microbial cells. The footprints were then analysed using XPS and ToF-SIMS. XPS results showed no significant differences between the footprints, but principal component analysis of the ToF-SIMS data enabled clear separation of MSC-footprints from the S. aureus and co-culture footprints (p < 0.03). ToF-SIMS also demonstrated 'race for the surface' between proteins, which suggest surface charge (zeta-potential) dependent protein adsorption. ToF-SIMS differentiated eukaryotic and bacterial footprints and has potential for post-hoc detection of implant-related infections based on the typical ToF-SIMS spectra.

Analysis of plastic deformation in cortical bone after insertion of coated and non-coated self-tapping orthopaedic screws

Insertion of internal fracture fixation devices, such as screws, mechanically weakens the bone. Diamond-like carbon has outstanding tribology properties which may decrease the amount of damage in tissue. The purpose of this study was to investigate methods for quantification of cortical bone damage after orthopaedic bone screw insertion and to evaluate the effect of surface modification on tissue damage. In total, 48 stainless steel screws were inserted into cadaver bones. Half of the screws were coated with a smooth amorphous diamond coating. Geometrical data of the bones was determined by peripheral quantitative computed tomography. Thin sections of the bone samples were prepared after screw insertion, and histomorphometric evaluation of damage was performed on images obtained using light microscopy. Micro-computed tomography and scanning electron microscopy were also used to examine tissue damage. A positive correlation was found between tissue damage and the geometric properties of the bone. The age of the cadaver significantly affected the bone mineral density, as well as the damage perimeter and diameter of the screw hole. However, the expected positive effect of surface modification was probably obscured by large variations in the results and, thus, statistically significant differences were not found in this study. This can be explained by natural variability in bone tissue, which also made automated image analysis difficult.

Wear and Friction of Unio Crassus Shell in Dry Sliding Contact with Steel

Biological materials such as shells possess a useful combination of mechanical properties. For instance, good fracture toughness combined with a relatively high hardness has been reported. The response of these properties to a tribological performance could presumably be very beneficial. Unfortunately no such research has been reported, although this kind of information is invaluable in possible utilization of biomimetic or biological processes in producing of materials.

In this work chemical composition of Unio Crassus shells were characterized using secondary ion mass spectroscopy (SIMS) and Rutherford backscattering spectroscopy (RBS) and the microstructure was determined with X-ray diffraction (XRD) and scanning electron microscopy (SEM). Specimens of 20×10 mm in size with a thickness of a few millimetres were cut and mechanically polished followed by ultrasonic cleaning in deionized water. Wear and friction measurements were performed in a pin-on-disc tester with a hardened steel pin 6 mm in diameter as a counter face. Tests were carried out in a relative humidity of 50 % at room temperature with a sliding speed of 15 mm/s. The measurements indicate a friction coefficient of 0.3 – 0.4 which is reasonable low. Moreover, wear resistance was found to be excellent. The wear resistance of the material was similar to those of the best synthetic diamond-like carbon films. The storage of the specimen at room temperature for 150 days deteriorated the material resulting in much worse tribological properties.

Nuadu concept for personal management of lifestyle related health risks

Majority of the health risks and diseases in the modern world are related to lifestyles, e.g., overweight, unhealthy diet, physical inactivity, sleep deprivation, and stress. Behavioral change towards healthy lifestyles is the key to the prevention and management of these risks, but early and efficient interventions are scarcely available. We present the Nuadu Concept, an ICT (Information and Communication Technologies) assisted wellness toolbox for the management of multiple, behavior-originated health risks. The concept is based on psychological models, which provide methods and motivation for behavior change. The individual is considered as the best expert of his/her own wellness. Thus, the Nuadu Concept provides a variety of personal wellness technologies and services, among which the user may freely choose the best tools for him/herself. We believe this approach has the potential to provide efficient, acceptable, available, and affordable wellness management support for a significant number of people.

Personal health promotion through personalized health technologies - Nuadu experience

Poor lifestyles - overweight, unhealthy diet, physical inactivity, sleep deprivation, and stress - are significant risk factors to chronic illnesses, which cause majority of the health care costs. Hence, behavioral change towards healthy lifestyles is one of the keys to health care cost containment. Personal health systems (PHS) offer tools to support behavioral change. As health risks, personal needs and preferences vary from an individual to another, personalization of the PHS is needed. In Nuadu project we have developed a PHS integrating several different personal health technologies. This system was studied in a large (N=354) randomized controlled trial where employees with several health risks participated in a health promotion program. The study will finish in June 2009. User feedback and technology usage logs reveal that especially simple mobile technologies were actively used during the program. However, usage models varied between individuals and time, and there was a significant number of both active users and non-users. The results emphasize that "one size" does not fit all, and instead of individual "killer applications", PHS with different personalizable and interoperable options should be developed. In addition, screening and profiling methods should be developed to identify those users who would best accept and benefit from technology-supported health promotion. Successful technologies combine high usability and conceptual simplicity to clear and perceivable added value for the end users.

Ultrasound transmission technique as a potential tool for physical evaluation of monolithic matrix tablets

The aim of this study was to investigate the effects of tablet porosity and particle size fraction of compacted Starch acetate powders, with and without model drug caffeine, on acoustic properties of tablets. The ultrasound velocity was determined from the transmission measurements. Tablets of starch acetate (SA DS 2.7) powder with two particle size fractions of 0-53 and 0-710 microm were compressed with a compaction simulator. Porosities of tablets varied in the range from 12% to 43% for both particle size fractions. Strong associations were found between the ultrasound velocity and physical properties of the tablets such as porosity and particle size fraction. Interestingly, ultrasound velocity was practically insensitive to inclusion of the model drug caffeine with the concentrations used. Based on this study ultrasound transmission method is a potential non-destructive tool for studying structural changes of tablets and other solid dosage forms.

Effect of human trabecular bone composition on its electrical properties

Mechanical properties of bone are determined not only by bone mineral density (BMD), but also by tissue trabecular structure and organic composition. Impedance spectroscopy has shown potential to diagnose trabecular bone BMD and strength, however, the relationships between organic composition and electrical and dielectric properties have not been systematically investigated. To investigate these issues organic composition of 26 human trabecular bone samples harvested from the distal femur and proximal tibia was determined and compared with relative permittivity, loss factor, conductivity, phase angle, specific impedance and dissipation factor measured at wide range (50 Hz to 5 MHz) of frequencies. A strong linear correlation was found between the relative permittivity at 1.2 MHz and trabecular bone fat content (r = -0.85, p<0.01, n=26). On the other hand, relative permittivity measured at 200 Hz served as a good predictor of water content (r = 0.83). Phase angle, specific impedance and especially conductivity were strongly related to the trabecular bone dry density and water content (|r| > or = 0.69). Variation in bone tissue collagen content was strongly related to the relative permittivity measured at 1.2 MHz (r = 0.64), but only moderately to other parameters. Glycosaminoglycan content showed no significant relations with any investigated electrical parameters. The present study indicates that if the trabecular bone composition is known, the relationships presented in this study could facilitate calculation of current field distribution, e.g. during electrical stimulation of osteogenesis. On the other hand, our results suggest that permittivity measured at low (<1 kHz) or high (>100 kHz) frequencies could be used, e.g. during implant surgery, for prediction of trabecular bone water or fat contents, respectively.

The effect of authentic metallic implants on the SAR distribution of the head exposed to 900, 1800 and 2450 MHz dipole near field

As the use of radiofrequency (RF) electromagnetic (EM) fields has increased along with increased use of wireless communication, the possible related health risks have also been widely discussed. One safety aspect is the interaction of medical implants and RF devices like mobile phones. In the literature, effects on active implants like pacemakers have been discussed but the studies of passive metallic (i.e. conductive) implants are rare. However, some studies have shown that the EM power absorption in tissues may be enhanced due to metallic implants. In this study, the effect of authentic passive metallic implants in the head region was examined. A half-wave dipole antenna was used as an exposure source and the specific absorption rate (SAR, W kg(-1)) in the near field was studied numerically. The idea was to model the presumably worst cases of most common implants in an accurate MRI-based phantom. As exposure frequencies GSM (900 and 1800 MHz) and UMTS (2450 MHz) regions were considered. The implants studied were skull plates, fixtures, bone plates and ear rings. The results indicate that some of the implants, under very rare exposure conditions, may cause a notable enhancement in peak mass averaged SAR.

Interrelationships between electrical properties and microstructure of human trabecular bone

Microstructural changes, such as reduction of trabecular thickness and number, are characteristic signs of osteoporosis leading to diminished bone strength. Electrical and dielectric parameters might provide diagnostically valuable information on trabecular bone microstructure not extractable from bone mineral density measurements. In this study, structural properties of human trabecular bone samples (n=26) harvested from the distal femur and proximal tibia were investigated using the computed microtomography (microCT) technique. Quantitative parameters, e.g. structural model index (SMI) or trabecular bone volume fraction (BV/TV), were calculated. In addition, the samples were examined electrically over a wide frequency range (50 Hz-5 MHz) using a two-electrode impedance spectroscopy set-up. Relative permittivity, loss factor, conductivity, phase angle, specific impedance and dissipation factor were determined. Significant linear correlations were obtained between the dissipation factor and BV/TV or SMI (|r| 0.70, p<0.01, n=26). Principal component analyses, conducted on electrical and structural parameters, revealed that the high frequency principal component of the dissipation factor was significantly related to SMI (r=0.72, p<0.01, n=26). The linear combination of high and low frequency relative permittivity predicted 73% of the variation in BV/TV. To conclude, electrical and dielectric parameters of trabecular bone, especially relative permittivity and dissipation factor, were significantly and specifically related to a trabecular microstructure as characterized with microCT. The data gathered in this study constitute a useful basis for theoretical and experimental work towards the development of impedance spectroscopy techniques for detection of bone quality in vitro or in special cases of open surgery.

Diurnal and weekly rhythms of health-related variables in home recordings for two months

Several telecare systems for long-term monitoring of the well-being of patients at home have been developed as an aid in healthcare and to reduce hospitalization costs. Most of the systems have been designed to measure only one or two variables. Because well-being is a combination of both psychological and physiological wellness, there is a need to monitor several psychophysiological variables simultaneously in out-of-hospital conditions for a long period. To understand better the variability of patients' wellness-related variables in long-term recordings, the knowledge of the normal variation in health-related variables in healthy people is necessary. In our study, 14 healthy working middle-aged men were studied daily for 24 h and periods of 50 to 79 days. The variables measured were beat-to-beat heart rate, motor activity, blood pressure, body weight, and temperature. At night respiratory frequency, time of movements, amount of quiet sleep, and ballistocardiographic respiratory variation were also measured. Heart rate variability in the waking period was calculated later (standard deviation of the 5 min average of the successive normal to normal beat to beat intervals). Daily self-reported well-being, activities, and consumption of alcohol were monitored by keeping a behavioral diary. After normalizing the physiological data, the diurnal and weekly variability was calculated for each variable. In several variables the most notable diurnal and weekly variability was found between working time and free time. In conclusion, diurnal and weekly rhythms in several wellness-related physiological and psychological variables were identified, depending on working and free-time in healthy middle-aged men.

Expression of ADAM9 (meltrin-gamma) around aseptically loosened total hip replacement implants

OBJECTIVE

To investigate the involvement of a disintegrin and the metalloproteinase ADAM9 (meltrin-gamma) in the formation of multinuclear giant cells and osteoclasts in aseptic loosening of hip replacement implants.

METHODS

We used in situ hybridization, immunohistochemical staining and western blotting of interface membrane surrounding loosened hip implants, macrophage-colony stimulating factor (M-CSF) and receptor activator of nuclear factor kappaB ligand (RANKL) costimulation and polymethyl methacrylate (PMMA) particle stimulation of human monocytes followed by immunofluorescence staining and flow cytometric analysis.

RESULTS

Morphometric analysis revealed that the ADAM9+ area in the revision total hip replacement (THR) interface was larger than in primary THR samples (37.6+/-5.1 vs 5.2+/-0.8%, P=0.002). Double immunofluorescence staining showed that CD68+ interface tissue macrophages and multinuclear giant cells were ADAM9+. ADAM9 mRNA containing mononuclear and multinuclear cells was often seen in a close spatial relationship with other ADAM9+ cells. Western blotting disclosed a 50 kDa ADAM9 band in tissue extracts. Upon M-CSF and RANKL costimulation of human monocytes, the ADAM9 staining pattern changed over time and ADAM9+ cells formed bi- and multinuclear cells. Flow cytometry disclosed that cells of the monocyte/macrophage lineage changed from ADAM9-negative cells into strongly positive cells during a 3-day culture.

CONCLUSION

ADAM9 is expressed in interface tissues around aseptically loosened THR implants. ADAM9 may play a role as a fusion molecule in the formation of multinuclear giant cells and osteoclasts from mononuclear precursors in diseases characterized by bone tissue destruction.

The effect of powder blend and tablet structure on drug release mechanisms of hydrophobic starch acetate matrix tablets

This study investigates the release mechanism of a hydrophilic drug (caffeine) from hydrophobic matrix tablets composed of starch acetate. Different particle size fractions of starch acetate were mixed with caffeine (22% V/V) to obtain various mixture organisations in the powder, as well as in the final tablet. The organisation of powder mixtures was calculated by the carrier payload of starch acetate particles, while the pore size distributions in tablets were measured by mercury intrusion porosimetry. A carrier payload below 1 indicated the existence of a free starch acetate particle surface, while numbers greater than 1 pointed to a complete occupation of the starch acetate particle surface area by caffeine particles. The carrier payload calculations gave a good prediction for the existence of a starch acetate matrix in the tablet structures. Caffeine matrices in tablets compressed from the mixtures could be detected by mercury intrusion porosimetry measurements. The existence of different matrices, as well as different pore networks, determined the physical changes of the tablets and the release mechanism of caffeine during dissolution tests. When a tablet contained only a caffeine matrix, rapid tablet disintegration and immediate release of the total amount of caffeine occurred. A single matrix of starch acetate resulted in tablets that remained intact, although cracks were formed. The co-existence of matrices of both materials created surface erosion of the tablet. The caffeine release profiles of tablets that remained intact or showed erosion were fitted by an equation containing both diffusional and relaxational factors to describe the effect of tablet porosity on drug release.

Interaction of mobile phones with superficial passive metallic implants

The dosimetry of exposure to radiofrequency (RF) electromagnetic (EM) fields of mobile phones is generally based on the specific absorption rate (SAR, W kg(-1)), which is the electromagnetic energy absorbed in the tissues per unit mass and time. In this study, numerical methods and modelling were used to estimate the effect of a passive, metallic (conducting) superficial implant on a mobile phone EM field and especially its absorption in tissues in the near field. Two basic implant models were studied: metallic pins and rings in the surface layers of the human body near the mobile phone. The aim was to find out 'the worst case scenario' with respect to energy absorption by varying different parameters such as implant location, orientation, size and adjacent tissues. Modelling and electromagnetic field calculations were carried out using commercial SEMCAD software based on the FDTD (finite difference time domain) method. The mobile phone was a 900 MHz or 1800 MHz generic phone with a quarter wave monopole antenna. A cylindrical tissue phantom models different curved sections of the human body such as limbs or a head. All the parameters studied (implant size, orientation, location, adjacent tissues and signal frequency) had a major effect on the SAR distribution and in certain cases high local EM fields arose near the implant. The SAR values increased most when the implant was on the skin and had a resonance length or diameter, i.e. about a third of the wavelength in tissues. The local peak SAR values increased even by a factor of 400-700 due to a pin or a ring. These highest values were reached in a limited volume close to the implant surface in almost all the studied cases. In contrast, without the implant the highest SAR values were generally reached on the skin surface. Mass averaged SAR(1 g) and SAR(10 g) values increased due to the implant even by a factor of 3 and 2, respectively. However, at typical power levels of mobile phones the enhancement is unlikely to be problematic.

Prediction of mechanical properties of human trabecular bone by electrical measurements

In trabecular bone, the interrelationships of electrical and dielectric properties with mechanical characteristics are poorly known. Information on these relations is crucial for evaluation of the diagnostic potential of impedance techniques. In this study, electrical and dielectric properties, i.e. permittivity, conductivity, phase angle, loss factor, specific impedance and dissipation factor of human trabecular bone samples (n=26, harvested from the distal femur and proximal tibia) were characterized in a wide frequency range (50 Hz-5 MHz). Mechanical properties, i.e. Young's modulus, ultimate strength, yield stress, yield strain and resilience of the samples (n=20) were determined by using destructive compressive testing. Subsequently, measurements of electrical and dielectric properties were repeated after mechanical testing. The measurements were also repeated for the control samples (n=6) that were not mechanically tested. Electrical, dielectric or mechanical properties showed no significant differences between the intact femoral and tibial samples. The electrical and dielectric parameters as well as the linear correlations between the dielectric and electrical parameters with mechanical parameters were strongly frequency dependent. At the frequency of 1.2 MHz, the relative permittivity showed the strongest linear correlations with the Young's modulus (r=0.71, p<0.01, n=20) and ultimate strength (r=0.73, p<0.01, n=20). Permittivity and dissipation factor showed statistically significant changes after mechanical testing. Our results suggest that the measurements of low frequency electrical and dielectric properties may provide information on the mechanical status of trabecular bone and, possibly, may even help to diagnose bone microdamage. In the future, these measurement techniques may be further developed for use during open surgery, such as bone grafting or total hip replacement surgery.

Proteoglycan and collagen sensitive MRI evaluation of normal and degenerated articular cartilage

Quantitative magnetic resonance imaging (MRI) techniques have earlier been developed to characterize the structure and composition of articular cartilage. Particularly, Gd-DTPA(2-)-enhanced T1 imaging is sensitive to cartilage proteoglycan content, while T2 relaxation time mapping is indicative of the integrity and arrangement of the collagen network. However, the ability of these techniques to detect early osteoarthrotic changes in cartilage has not been demonstrated. In this study, normal and spontaneously degenerated bovine patellar cartilage samples (n=32) were investigated in vitro using the aforementioned techniques. For reference, mechanical, histological and biochemical properties of the adjacent tissue were determined, and a grading system, the cartilage quality index (CQI), was used to score the structural and functional integrity of each sample. As cartilage degeneration progressed, a statistically significant increase in the superficial T2 (r=0.494, p<0.05) and a decrease in superficial and bulk T1 in the presence of Gd-DTPA(2-) (r=-0.681 and -0.688 (p<0.05), respectively) were observed. Gd-DTPA(2-)-enhanced T1 imaging served as the best predictor of tissue integrity and accounted for about 50% of the variation in CQI. The present results reveal that changes in the quantitative MRI parameters studied are indicative of structural and compositional alterations as well as the mechanical impairment of spontaneously degenerated articular cartilage.

Apparatus to test insertion and removal torque of bone screws

This paper describes affordable equipment for testing bone screw torque, corresponding to ASTM standard F543-00 for testing metallic medical bone screws. Correct testing of thin and long bone screws is essential due to screw failures during insertion and removal of the screws. Furthermore, insertion torque is an important factor in predicting fixation strength, screw pull-out force and effects of surface treatment of screws. The capability of the custom-built tester was determined using polytetrafluoroethylene and wood disc samples and bone screws. Bovine cortical bones allowed testing to the failure limit, i.e. the torque increased in long screws to the fracture limit. For 2.7 and 3.5 mm thick self-tapping cortical bone screws, the failure torques were 30-50 per cent higher than the minimum values required by the standard (1.0 and 2.3 N m respectively). The equipment provided reproducible results and fulfilled the ASTM standard very well. Preliminary testing with amorphous diamond coated bone screws showed good durability of the coating and on average 10-15 per cent lower torque values compared with uncoated screws. The equipment can be used to measure insertion and removal torques as described in the standard. Furthermore, it also allows testing of normal screws and bolts.

A programme of behaviour modification and nutrition counselling in the treatment of obesity: a randomised 2-y clinical trial

OBJECTIVE

To compare two group treatment programmes for obese outpatients. Both programmes included behaviour modification, nutrition counselling, very-low-calorie diet (VLCD) and a continuous measuring of metabolic and anthropometrical status, but they differed regarding the treatment intensiveness. The main aim was to study whether intensive treatment gives a larger weight reduction compared with less intensive treatment and what level of input from health care personnel is needed to reach adequate treatment results.

DESIGN

A 2-y randomised clinical trial.

SUBJECTS

A total of 43 obese subjects aged 24-60 y, BMI 35 kg/m(2) (29-48).

INTERVENTION

Two programmes were used. Both were based on group therapy and were supervised by a dietitian and a psychologist. Group 1 received a continuous intensive treatment with planned group meetings every fortnight during the first year and six group meetings the second year. Group 2 had planned group meetings every third month. Anthropometrical and metabolic data were measured every third month in both groups. The VLCD periods were the same.

RESULTS

There was no evidence that a more intensive treatment promotes a larger weight reduction. Weight reduction after 1 y: group 1, -7.6 (+/-0.97) kg, BMI -2.6 (+/-0.3) kg/m(2); group 2, -6.4 (+/-1.16) kg, BMI -2.2 (+/-0.4) kg/m(2). Weight reduction after 2 y: group 1, -6.8 (+/-1.4) kg, BMI -2.4 (+/-0.3) kg/m(2); group 2, -8.6 (+/-1.6) kg, BMI -3.0 (+/-0.3) kg/m(2). The dropout rate was 26%.

CONCLUSION

There were no significant differences in weight reduction, compliance or dropout rate between the groups and there was no evidence that a more intensive treatment promotes a larger weight reduction. This observation is of value when setting up treatment programmes. To measure the metabolic and anthropometrical status during the treatment and to give continuous feedback to the subjects seem to be important factors for compliance. Both treatment programmes gave highly significant weight reductions in the range of 5-10%, which has been referred to as a realistic goal for the treatment of obese patients.

Ultrasound indentation of normal and spontaneously degenerated bovine articular cartilage

OBJECTIVE

We have previously developed a handheld ultrasound indentation instrument for the diagnosis of cartilage degeneration. The instrument has been demonstrated to be capable of quantifying mechanical and acoustic properties of enzymatically degraded and normal bovine articular cartilage in vitro and in situ. The aim of this study was to investigate the sensitivity of the instrument to distinguish between normal and spontaneously degenerated (e.g., in osteoarthrosis) articular cartilage in vitro.

DESIGN

Thirty articular cartilage samples were prepared from the bovine lateral patellae: 19 patellae with different degenerative stages and 11 patellae with visually normal appearance. Cartilage thickness, stiffness (dynamic modulus) and ultrasound reflection from the cartilage surface were measured with the handheld instrument. Subsequently, biomechanical, histological and biochemical reference measurements were conducted.

RESULTS

Reproducibility of the measurements with the ultrasound indentation instrument was good. Standardized coefficient of variation was < or =6.1% for thickness, dynamic modulus and reflection coefficient. Linear correlation between the dynamic modulus, measured with the ultrasound indentation instrument, and the reference dynamic modulus was high (r=0.993, n=30, P<0.05). Ultrasound reflection coefficient, as determined from the cartilage surface, showed high linear correlations (typically r(2)>0.64, n=30, P<0.05) with the cartilage composition and histological or mechanical properties. The instrument was superior compared to visual evaluation in detecting tissue degeneration.

CONCLUSION

This study indicates that the ultrasound indentation technique and instrument may significantly improve the early diagnosis of cartilage degeneration. The results revealed that visual evaluation is insensitive for estimating the structural and mechanical properties of articular cartilage at the initial stages of degeneration.

Electrical and dielectric properties of bovine trabecular bone--relationships with mechanical properties and mineral density

Interrelationships of trabecular bone electrical and dielectric properties with mechanical characteristics and density are poorly known. While electrical stimulation is used for healing fractures, better understanding of these relations has clinical importance. Furthermore, earlier studies have suggested that bone electrical and dielectric properties depend on the bone density and could, therefore, be used to predict bone strength. To clarify these issues, volumetric bone mineral density (BMDvol), electrical and dielectric as well as mechanical properties were determined from 40 cylindrical plugs of bovine trabecular bone. Phase angle, relative permittivity, loss factor and conductivity of wet bovine trabecular bone were correlated with Young's modulus, yield stress, ultimate strength, resilience and BMDvol. The reproducibility of in vitro electrical and dielectric measurements was excellent (standardized coefficient of variation less than 1%, for all parameters), especially at frequencies higher than 1 kHz. Correlations of electrical and dielectric parameters with the bone mechanical properties or density were frequency-dependent. The relative permittivity showed the strongest linear correlations with mechanical parameters (r > 0.547, p < 0.01, n = 40, at 50 kHz) and with BMDvol (r = 0.866, p < 0.01, n = 40, at 50 kHz). In general, linear correlations between relative permittivity and mechanical properties or BMDvol were highest at frequencies over 6 kHz. In addition, a significant site-dependent variation of electrical and dielectric characteristics, mechanical properties and BMDvol was revealed in bovine femur (p < 0.05, Kruskall-Wallis H-test). Based on the present results, we conclude that the measurement of electrical and dielectric properties provides quantitative information that is related to bone quantity and quality.

Acid attack and cathepsin K in bone resorption around total hip replacement prosthesis

Normal bone remodeling and pathological bone destruction have been considered to be osteoclast-driven. Osteoclasts are able to attach to bare bone surface and produce an acidic subcellular space. This leads to acid dissolution of hydroxyapatite, allowing cathepsin K to degrade the organic type I collagen-rich osteoid matrix under the acidic condition prevailing in Howship lacunae. Using a sting pH electrode, the interface membrane around a loosened total hip replacement prosthesis was found to be acidic. Confocal laser scanning disclosed irregular demineralization of the bone surface in contact with the acidic interface. Cathepsin K, an acidic collagenolytic enzyme, was found in interface tissue macrophages/giant cells and pseudosynovial fluid. Tissue extracts contained high levels of cathepsin K messenger RNA (mRNA) and protein. These observations suggest the presence of an acid- and cathepsin K-driven pathological mechanism of bone resorption, mediated not by osteoclasts in subosteoclastic space, but rather by the uncontrolled activity of macrophages in extracellular space.

TERVA: system for long-term monitoring of wellness at home

Long-term monitoring of physiological and psychosocial variables in out-hospital conditions would be beneficial for investigating changes in wellness status of an individual or to understand interaction between physiological and behavioral processes. We aimed to design a personal wellness monitoring system (TERVA), which would allow monitoring of wellness-related variables at home for several weeks or even months. The designed TERVA system runs on a laptop computer and interfaces with different measurement devices through a serial interface. Measured variables include beat-to-beat heart rate, motor activity, blood pressure, weight, body temperature, respiration, ballistocardiography, movements, and sleep stages. In addition, self-assessments of daily well-being and activities are stored by keeping a behavioral diary. To test the system, one healthy man used the system for 10 weeks. The system was successfully applied in out-hospital conditions. The success rate of the measurements was 70-91%, depending on the variable under consideration. The pilot study indicated that the recorded data accurately reflected the health status of the subject. The TERVA system provides a method to record and investigate wellness-related data over several weeks, or even months, outside the hospital among subjects capable of using a personal computer. Several applications of the system are discussed.

Reduced serotonin transporter binding in binge eating women

RATIONALE

There is evidence that abnormalities in brain dopamine, norepinephrine and serotonin metabolism may play an important role in binge eating. Serotonin-active antidepressant drugs have also been found to decrease binge eating.

OBJECTIVE

We investigated serotonin transporter binding in obese binge-eating women. Eleven obese binge-eating and seven obese control women participated in the study. The subjects were not taking any medication known to affect serotonin (5-HT) transporters.

METHODS

We used single-photon emission tomography (SPECT) with the radioligand 123I-labelled nor-beta-CIT, which specifically labels 5-HT transporters.

RESULTS

Obese binge-eating women showed significantly decreased 5-HT transporter binding in the mid-brain compared with obese controls (2.1 +/- 0.5 versus 2.9 +/- 0.5, respectively).

CONCLUSIONS

SPECT imaging with a ligand specific for 5-HT transporters can be used to assess altered serotonin transporter binding in the living human brain. The results tentatively suggest that 5-HT transporter binding is decreased in binge-eating women.

Activation of 5-HT2A receptors impairs response control of rats in a five-choice serial reaction time task

The present experiments investigated the effects of agents acting at serotonin (5-HT)-2 receptors on the performance of rats in a choice serial reaction time (5-CSRT) task in order to examine the role of 5-HT2 receptors in the modulation of attention and response control. The results indicate that DOI, [(+/-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane hydrochloride; 0.05, 0.1 and 0.2 mg/kg, subcutaneously], a 5-HT(2A/2C) agonist, slightly impaired the choice accuracy of the well performing rats and markedly increased their premature responding. DOI (0.05 and 0.1 mg/kg) had no effect on the latency to collect earned food pellets or to respond correctly, indicating that these lower doses of DOI did not reduce motivation for the food reward in this task. The selective effect of a low dose of DOI (0.1 mg/kg) on premature responding was completely blocked by ketanserin (0.2 mg/kg), a 5-HT2A antagonist, and ritanserin (0.3 mg/kg), a 5-HT(2A/2C) antagonist, but only partially blocked by a high dose of SER082 (1.0 mg/kg), a 5-HT2C antagonist. In contrast to DOI, mCPP, [1-(3-phenyl)piperazine; 0.05 and 0.15 mg/kg], a 5-HT2C agonist, had no effect on choice accuracy or premature responding, but it reduced behavioral activity and/or arousal as indicated by the decreased number of trials completed and increased the probability of omissions. SER082 (1.0 mg/kg) blocked the effects of mCPP on performance. These data suggest that the overactivation of 5-HT2A receptors impairs response control in a 5-CSRT task, whereas the overactivation of 5-HT2C receptors can affect behavioral activity and/or arousal state of the animals for this food rewarded task.

The counterface, surface smoothness, tolerances, and coatings in total joint prostheses

Proper counterface material combinations, surface finish, and tolerances of contact surfaces are important issues in minimizing friction, wear, and corrosion of total joint prostheses. In the current study, the potential of novel amorphous diamond coatings to solve some present problems in total joint prostheses was studied by using tribological tests with a hip joint simulator and pin-on-disk testers. Based on the tests, the wear of amorphous diamond is negligible compared with conventional hip joint materials (10,000 to 1,000,000 times lower). The coefficient of friction of diamond-coated artificial hip joint was 0.03 to 0.06 when tested in saline solution with loads from 200 to 1000 kg for as many as two million cycles. The friction remained stable throughout the tests. Methylmethacrylate (bone cement) is a typical source of third body wear particles in cemented total hip replacements. The wear tests showed that bone cement (containing hard ceramic particles of barium sulfate or zirconia) severely scratched cobalt chromium molybdenum alloy samples. These scratches enhance the wear of softer counterpart materials, such as polyethylene or bone cement, whereas diamond-coated surfaces remained undamaged. High quality amorphous diamond coatings offer superior stability (minimal wear debris release in surrounding tissues) and good biomechanical performance.

Physical activity levels and body weight in a nationally representative sample in the European Union

OBJECTIVES

The main objectives of this pan-European study were: (1) to identify different types of physical activity and the time devoted to them, (2) to assess physical activity/inactivity at work and in leisure time, and (3) to determine self-reported body weight and height.

DESIGN AND SUBJECTS

In each member state of the EU, approximately 1000 adults, aged 15 years or more, were selected to participate in an interview-assisted face-to-face questionnaire on physical activity and body weight. In each country, sample selection was quota-controlled to ensure national representativeness. Overall, 15,239 subjects in the EU completed the study.

RESULTS

On average in the EU, nearly three-quarters of the population participate in some kind of activity. In general, the highest proportions of participants were found in the Nordic countries and the lowest in the southern ones. At the European level, the five most common activities include walking, gardening, cycling, keep fit and swimming. Higher participation rates were found among men, younger subjects and those with a higher level of education. The majority of Europeans fall within the normal body mass index (BMI) range but more than one-third are overweight (31%) or obese (10%) and 11% have a BMI below 20.

CONCLUSIONS

Several risk groups related to physical activity emerge from this survey: women, those with a lower level of education, older subjects, the overweight/obese and the underweight. Programmes to promote physical activity need to be tailored to the different groups identified in each country/region in order to increase adherence of non-participants and for the maintenance of those already engaged in activities.

Recent body-weight changes and weight loss practices in the European Union

OBJECTIVES

The aim of this paper is to describe recent weight changes and weight loss practices in the EU, and in particular to describe the group of subjects who were in a recent state of weight gain.

DESIGN AND SUBJECTS

Overall, 15,239 adults aged 15 years and upwards composed of 1000 from each EU member state were selected to complete the interview-assisted face-to-face questionnaire. In each member state, sample selection was quota-controlled to ensure national representativeness.

RESULTS

This survey points to a fairly alarming tendency of more normal weight, overweight or obese European people being in a state of weight gain rather than weight loss. But it is also worrying that almost a fifth of underweight people are in the process of losing more weight. The recommendations for interventions to promote weight loss might be somewhat different between countries in the EU as the common weight loss practices differ between such countries. Overall, a campaign alone may not be effective in encouraging people to do more physical activity in Europe. Additional methods should be found. Furthermore, a combination of diet and exercise as a method of weight control is underestimated or undervalued by the general population who are either overweight or obese.

Psychological and physiological characteristics of sweet food "addiction"

OBJECTIVE

Drug addicts in general can be distinguished from nonaddicts by their affective and physiological and craving responses to drug-related cues. The purpose of this study was to examine similar affective, physiological, and behavioral variables in chocolate "addicts" and control subjects.

METHODS

Sixteen addicts and 15 control subjects took part in two laboratory experiments in which their heart rate, salivation, and self-reported responses were measured.

RESULTS

In the presence of external chocolate cues, chocolate addicts were more aroused, reported greater cravings, experienced more negative affect, and also ate more chocolate than control subjects. Self-report measures on eating attitudes and behavior, body image, and depression confirmed that a relationship exists between "chocolate addiction" and problem eating. Chocolate addicts showed more aberrant eating behaviors and attitudes than controls, and were also significantly more depressed.

DISCUSSION

Chocolate addicts may be considered to be a parallel with addicts generally, because they differ from controls in craving for chocolate, eating behavior, and psychopathology (in respect of eating and affect).

Difficulties in changing the diet in relation to dietary fat intake among patients with coronary heart disease

OBJECTIVE

To study barriers in following nutritional advice among coronary heart disease patients in relation to dietary fat intake.

DESIGN

A cross-sectional study using 4-day food records and a questionnaire with regard to barriers to or difficulties in following dietary advice.

SUBJECTS

Altogether, 362 male subjects with coronary heart disease from two separate patient populations (91 + 271) were included in the study, with the mean age of 50 years and 60 years, respectively. The patients were classified into low (< or = 30 E%) or high (> 30 E%) fat intake groups. The patients with low dietary fat intake obtained on an average 10 E% less energy from fat as compared to the high dietary fat intake group.

RESULTS

Overall, most patients with coronary heart disease reported difficulties in following nutritional advice when eating in social situations. Patients with high dietary fat intake reported more frequently than patients with low fat intake that they eat like other people without thinking about what they eat. On the other hand, there were no differences between the high and low fat intake groups in the barriers: eating at work, food price, shopping, taste or knowledge of nutrition.

CONCLUSIONS

Our results suggest that the sensitivity to social influence is an important factor explaining noncompliance with dietary advice among patients with high dietary fat intake.

Biocompatibility of silicon carbide in colony formation test in vitro. A promising new ceramic THR implant coating material

We studied the possible use of silicon carbide (SiC) as a ceramic coating material of titanium-based total hip replacement (THR) implants. The idea is to prevent wear debris formation from the soft titanium surface. SiC is a hard and tightly bonding ceramic surface material, and because of these physical properties it is not easily degradable, as is the case with hydroxyapatite. Our previous in vivo and in vitro studies have indicated that SiC and hydroxyapatite are equally biocompatible regarding particle size for phagocytosis. The present cytotoxicity test using JCRB0603 cells showed that 5 microns SiC particles inhibited colony outgrowth by one-third (67% + 10% vs control), while SiC-coated pins did not cause any inhibition and acted similarly to uncoated titanium pins. The results support the hypothesis that SiC is a promising ceramic THR implant coating material.

Systemic administration of atipamezole, a selective antagonist of alpha-2 adrenoceptors, facilitates behavioural activity but does not influence short-term or long-term memory in trimethyltin-intoxicated and control rats

The present study used trimethyltin (TMT)-intoxicated rats as a model for the behavioural syndrome seen after neuronal damage to the limbic system. Behavioural assessments indicated increased locomotor activity and reduced number of groomings in an open-arena task in TMT-intoxicated (6.6 mg/kg as a free base) rats, as has been found previously. A novel finding was the severe deficit in swimming to a visible platform in the water maze task, with reduced swimming speed at the beginning of the training period. During the reacquisition phase of a radial arm maze task, TMT-intoxicated rats made more short-term and long-term memory errors, and their behavioural activity was increased in comparison with controls. The administration of atipamezole (300 micrograms/kg), a selective antagonist of alpha 2-adrenoceptors, enhanced locomotor activity compared to saline-treated rats, but these effects did not differ between the TMT group and their controls. Atipamezole did not enhance short-term or long-term memory in either TMT or control groups. Taken together, the present data indicate that TMT intoxication is a model for global dementia rather than for a specific loss of relational memory. Previous studies on the neurochemical effects of TMT and the alleviation or prevention of neurotoxicity of TMT are reviewed.

Diamond coated total hip replacements

Diamond has many superior, desired characteristics of implant materials such as low friction, high wear and corrosion resistance, and well bonding surface to bone. The potential of diamond for total hip replacement implants was studied in the form of amorphous diamond coatings on conventional metal implant materials. Amorphous diamond coatings (sp3 bonding fraction 80%, thickness 0.2 to 10 microns) were deposited on stainless steel AISI316L, Ti6A14V, and CoCrMo alloys using filtered pulsed plasma are discharge method. Superior attachment of coatings to the implant materials was achieved by using high energy plasma beams to deposit amorphous diamond and proper intermediate layers. Previously it was shown that these coatings are biocompatible causing no local tissue reactions. Tribologic studies using a pin on disk apparatus with coated or uncoated implant materials in 1 wt.% NaCl distilled water were performed. A simplified hip joint simulator was used for preliminary testing of metal on polyethylene and metal on metal artificial hip joints modified with amorphous diamond coating. The average coefficients of friction were typically in the range of 0.03 to 0.11 for amorphous diamond coated materials. In the case of metal on metal hip implants, the average friction during initial running in period was improved (coefficient of friction = 0.07) compared with the same metal on metal pair (coefficient of friction = 0.22) and sliding was significantly smoother. In pin on disk wear tests, the average wear factors obtained were 140.10(-6), 5.0.10(-6), and << 0.1.10(-6) mm3/Nm for the pairs of AISI316L, CoCrMo, and the same materials with amorphous diamond coating. The corrosion rates of these implant materials in 10 wt.% HCl solution were decreased by a factor of 10,000 to 15,000 and any damage of the coatings was not observed in 6 months. The results of the tests show that in all the combinations studied, amorphous diamond coating improved definitely the wear and corrosion resistance compared with the uncoated materials.

Reasons for initiation and cessation of eating in obese men and women and the affective consequences of eating in everyday situations

Reasons for the initiation and termination of eating were investigated in 78 female and 36 male obese subjects following a weight control programme. Self-monitoring diaries were completed during a 24-h period, in which subjects selected the main reason for starting and stopping an eating episode. Additionally, subjects recorded mood before and after eating using visual analogue scales. Hunger was chosen as a reason to start eating in only 20% of cases. Environmental cues such as mealtime were selected as the main reason for the initiation of the majority of eating episodes. In contrast, self-assessments such as "I felt I had eaten enough" was the main reason for terminating eating (39.4%). Gender differences in the reasons for initiating eating revealed a greater tendency for men to initiate eating for environmental reasons than women, whereas the opposite was found for the termination of eating, with women more likely to stop eating for environmental reasons than men. Changes in affect during eating revealed a significant decline in negative emotions such as tension and tiredness, and in the heavier subjects a trend for increased happiness was observed following eating. As hunger was less commonly reported as a reason to start eating than external reasons, treatment strategies for the obese might benefit by targeting individual reasons for meal initiation.

Alpha2-adrenergic control of dopamine overflow and metabolism in mouse striatum

The effects of the alpha2-adrenoceptor drugs, medetomidine and atipamezole, on dopamine overflow evoked by low (6 Hz-10 s) and high (50 Hz-4 s) frequency electrical stimulation of the median forebrain bundle were studied in striatum of BALB/C mice anaesthetized with chloral hydrate with fast in vivo voltammetry techniques. The effects of these drugs on the basal concentrations of dopamine metabolites were also investigated by means of differential pulse voltammetry. Medetomidine dose dependently decreased dopamine overflow in nucleus accumbens in the dose range 5-100 microg/kg, s.c. This effect was seen only at low frequency stimulation and reached 85% at a dose of 100 microg/kg. Medetomidine also decreased the basal concentration of striatal homovanillic acid. This effect did not exceed 35%. Atipamezole antagonized the inhibitory effects of medetomidine on the dopamine overflow. but showed no effect itself. We suggest that alpha2-adrenoceptors in dopaminergic terminal fields in the mouse striatum are involved in the regulation of dopamine release at physiological stimulation frequencies.

Healthy dietary practices among European students

Predictors of 5 healthy dietary habits were examined in data from the European Health and Behaviour Survey (A. Steptoe & J. Wardle, 1996), a study of over 16,000 students from 21 European countries. The level of practice of these healthy dietary habits was low. Significant univariate associations with healthy dietary habits were identified for gender, weight, dieting status, dietary health beliefs, nutrition knowledge, and health locus of control. In multivariate analyses, only gender, dieting status, and dietary health beliefs were significant predictors of healthy dietary habits. The practical implications of these results for dietary health promotion are discussed.

Systemic administration of atipamezole, an alpha 2-antagonist, can reduce scopolamine-induced hyperactivity in rats

The present study investigated whether an alpha 2-adrenoceptor antagonist (atipamezole) can influence hyperactivity induced by the systemic administration of scopolamine. In the water maze (WM) task, scopolamine (scop) 0.25 mg/kg treatment significantly increased swimming speed during the acquisition phase of this task. Atipamezole (ati) 30 micrograms/kg slightly reduced swimming speed both in saline- and in scop-treated rats. Ati 300 micrograms/kg slightly reduced swimming speed in saline-treated rats, and it prevented the scop-induced increase in swimming speed, because ati300-scop treated rats swam more slowly than the saline-saline group. In addition, ati 300 micrograms/kg reduced the total distance swum in scop-treated rats during a free swim trial (the platform was removed from the pool) performed 1 day after the acquisition phase of the WM test, even though it did not affect this parameter when administered alone. In the open arena task, which assessed the ambulation of rats when the pool was covered with a solid floor, scopolamine dose-dependently increased locomotor activity. The rats ambulated more when treated with scop 0.50 mg/kg compared to vehicle treatment, whereas the effect of scop 0.25 mg/kg treatment did not reach significance. In a test investigating the effects of ati 300 micrograms/kg and scop 0.50 mg/kg given singly or combined, the rats ambulated more during both ati 300 micrograms/kg and scop 0.50 mg/kg treatments given alone, but when combined, the rats ambulated less than during scop-saline treatment even though this was more than during control (saline-saline) treatment. These results indicate that the systemic administration of an alpha 2-antagonist can reduce hyperactivity induced by scopolamine.

Healthy dietary practices among European students

Predictors of 5 healthy dietary habits were examined in data from the European Health and Behaviour Survey (A. Steptoe & J. Wardle, 1996), a study of over 16,000 students from 21 European countries. The level of practice of these healthy dietary habits was low. Significant univariate associations with healthy dietary habits were identified for gender, weight, dieting status, dietary health beliefs, nutrition knowledge, and health locus of control. In multivariate analyses, only gender, dieting status, and dietary health beliefs were significant predictors of healthy dietary habits. The practical implications of these results for dietary health promotion are discussed.

Sources used and trusted by nationally-representative adults in the European Union for information on healthy eating

OBJECTIVE

To assess what sources of information on healthy eating are used and in particular to ascertain which are the most trusted by European adults.

DESIGN

A cross-sectional study in which quota-controlled, nationally-representative samples of approximately 1000 adults from each country completed a face-to-face interview-assisted questionnaire.

SETTING

The survey was conducted between October 1995 and February 1996 in the 15 member states of the European Union.

SUBJECTS

14331 subjects (aged 15 y upwards) completed the questionnaire. Data were weighted by population size for each country and by sex, age and regional distribution within each member state.

RESULTS

The five sources of information most frequently selected were: TV/radio (29%), magazines and newspapers (27%), health professionals (26%), food packages (22%) and relatives/friends (22%). Those used by less than 5% of the population included vegetarian and slimming societies and women's organizations. The reliance on health professionals for information was stronger for females and tended to increase with age. The most trusted sources of information in almost all countries were health professionals (91%) and government agencies (80%) with great consistency across countries. 15% of Europeans stated that they did not get any information on healthy eating.