Investigation of the neural basis of expectation-based analgesia in the human brainstem and spinal cord by means of functional magnetic resonance imaging.

PURPOSE: The expected intensity of pain resulting from a noxious stimulus has been observed to have a strong influence on the pain that is perceived. The neural basis of pain reduction, as a result of expecting lower pain, was investigated using functional magnetic resonance imaging (fMRI) in the brainstem and spinal cord. METHODS: Functional MRI studies were carried out in a region spanning the brainstem and cervical spinal cord in healthy participants. Participants were familiarized with a noxious heat stimulus and study procedures in advance, and were informed during each trial that either a heat calibrated to produce moderate pain (Base state), or a temperature 1 °C lower (Low state), would be applied to their hand. However, the Base temperature was applied in every trial. RESULTS: Pain ratings were significantly reduced as a result of expecting lower temperatures. FMRI results demonstrate blood oxygenation-level dependent (BOLD) signal variations in response to participants being informed of the stimulus to expect, in advance of stimulation, and in response to stimulation. Significant coordination of BOLD signals was also detected across specific brainstem and spinal cord regions, with connectivity strengths that varied significantly with the study condition, and with individual pain ratings. The results identify regions that are known to be involved with arousal and autonomic regulation. CONCLUSIONS: Expectation-based analgesia is mediated by descending regulation of spinal cord nociceptive responses. This regulation appears to be related to arousal and autonomic regulation, consistent with the cognitive/affective dimension of pain.

Correlating quantitative MR imaging with histopathology in X-linked adrenoleukodystrophy.

BACKGROUND AND PURPOSE: Quantitative MR imaging techniques may improve the pathologic specificity of MR imaging regarding white matter abnormalities. Our purposes were to determine whether ADC, FA, MTR, and MRS metabolites correlate with the degree of white matter damage in patients with X-ALD; whether differences in ADC, FA, and MTR observed in vivo are retained in fresh and formalin-fixed postmortem brain tissue; and whether the differences predict histopathology. MATERIALS AND METHODS: MRS metabolites, MTR, ADC, and FA, were determined in 7 patients with X-ALD in 3 white matter areas (NAWM, active demyelination, and complete demyelination) and were compared with values obtained in 14 controls. MTR, ADC, and FA were assessed in postmortem brains from 15 patients with X-ALD and 5 controls. Values were correlated with the degree of astrogliosis and density of myelin, axons, and cells. Equations to estimate histopathology from MR imaging parameters were calculated by linear regression analysis. RESULTS: MRS showed increased mIns, Lac, and Cho and decreased tNAA in living patients with X-ALD; the values depended on the degree of demyelination. MTR, ADC, and FA values were different in postmortem than in vivo white matter, but differences related to degrees of white matter damage were retained. ADC was high and FA and MTR were low in abnormal white matter. Correlations between histopathologic findings and MR imaging parameters were strong. A combination of ADC and FA predicted pathologic parameters best. CONCLUSIONS: Changes in quantitative MR imaging parameters, present in living patients and related to the severity of white matter pathology, are retained in postmortem brain tissue. MR imaging parameters predict white matter histopathologic parameters.

Color adjustment potential of resin composites.

The study objective was to explore a new method for quantifying the color adjustment potential originating from physical translucency on a set of 7 resin composites, and then for testing the hypothesis that color adjustment potential is dependent on the composites and shades studied. Two-composite specimens (an outer base shade with an inner hole filled with inner test shades) and single-composite specimens of all shades were made. A 1-mm circular area, with its center in the middle of the specimen (P0mm), was measured by means of spectroradiometry. A newly developed equation for quantification of the color adjustment potential was tested. Color adjustment potential at P0mm ranged from -0.19 (negative color adjustment/contrast) to 0.61. Within the limitations of this study, a newly developed concept and equation have proved the existence of the physical component of color adjustment of translucent dental materials. Color adjustment potential was dependent on composite and shade.

Clinical performance of osteoporosis risk assessment tools in women aged 67 years and older.

UNLABELLED: Clinical performance of osteoporosis risk assessment tools was studied in women aged 67 years and older. Weight was as accurate as two of the tools to detect low bone density. Discriminatory ability was slightly better for the OST risk tool, which is based only on age and weight. INTRODUCTION: Screening performance of osteoporosis risk assessment tools has not been tested in a large, population-based US cohort. METHODS: We conducted a diagnostic accuracy analysis of the Osteoporosis Self-assessment Tool (OST), Osteoporosis Risk Assessment Instrument (ORAI), Simple Calculated Osteoporosis Risk Estimation (SCORE), and individual risk factors (age, weight or prior fracture) to identify low central (hip and lumbar spine) bone mineral density (BMD) in 7779 US women aged 67 years and older participating in the Study of Osteoporotic Fractures. RESULTS: The OST had the greatest area under the receiver operating characteristic curve (AUC 0.76, 95% CI 0.74, 0.77). Weight had an AUC of 0.73 (95% CI 0.72, 0.75), which was >or=AUC values for the ORAI, SCORE, age or prior fracture. Using cut points from the development papers, the risk tools had sensitivities >or=85% and specificities

Calculation of colour resulting from composite/compomer layering techniques.

This study determined the influence of optical properties of constituent layers on the colour of double-layer aesthetic filling materials. Multiple regression equations for the Commission Internationale de I'Eclairage (CIE) L*, a* and b* of layered materials were calculated from the optical values of the covering and underlying layers. Specimens (10 mm diameter, 1 mm thickness) of two light-cured resin composites and one compomer of seven to 11 shades were used. CIE L*, a* and b* values of each specimen were measured with a colour spectrophotometer backed by a standard white background. The scattering coefficient (S), absorption coefficient (K), contrast ratio (C) and translucency parameter (T) were calculated. Double-layered specimens were formed in optical contact by joining two different shades from the same material, or resin composite as covering with a compomer underlying layer. Each of the L*, a* and b* of layered material was used as a dependent variable, and 14 optical values of underlying and covering layers were used as independent variables in forward regression analysis (P = 0.01). CIE L* after layering had a positive correlation with S of covering layer (correlation coefficient; beta = 0.79-0.91, P < 0.01) and a correlation with L* of underlying layer (beta = 0.14-0.16). CIE a* after layering had a correlation with a* of covering layer (beta = 0.83-0.94) and a correlation with a* of underlying layer (beta = 0.30-0.56). CIE b* after layering had a correlation with b* of covering layer (beta = 0.77-0.90) and a correlation with T of covering layer (beta = 0.40-0.59). The layered colour of these materials can be predicted by the derived regression equations within the limitations of this study. CIE L*, a* and b* values of double-layer material are mainly influenced by S, CIE a* and b* of covering layer, respectively.

Efficacy of conventional and experimental techniques for denture repair.

This study investigated the efficacy of one experimental and three conventional techniques for denture repair. Forty maxillary dentures were constructed in dental stone casts duplicated from an edentulous copper-aluminium maxillary master cast. Two groups of 20 dentures each were prepared with Lucitone 199 (water-bath, 8 h/74 degrees C) or Acron MC (microwave, 3 min/500 W) denture base materials processed in gypsum moulds. The 40 dentures were all separated sagittally in the middle. After that, five dentures of each denture base material were repaired with one of the four following techniques: L (Lucitone 199, water-bath, 8 h/74 degrees C, gypsum mould), A (Acron MC, microwave, 3 min/500 W, gypsum mould), AR (Acron MC/R, autopolymerized, 60 psi/45 degrees C/15 min) and the experimental technique AS (Acron MC, 1 min/500 W + 1 min/0 W + 1 min/500 W, hard silicone mould). The parameters denture accuracy (DA), horizontal (HC) and vertical changes (VC) of the occlusal plane measured the efficacy of the repair techniques. The DA was determined by weighing a film of silicone impression material set in contact to the tissue surface of the denture seated on the metallic master die. For HC, cross-arch measurements were made among reference marks drilled on the teeth 11, 21, 16 and 26. The VC was obtained by calculating the relative differences in height between similar teeth of each semi-arch (pairs 13-23, 14-24, 15-25 e 16-26). For DA, HC and VC, the percentage differences between the percentage means obtained before and after repair were calculated and grouped for comparisons. Analysis of variance (SuperANOVA) and means compared by Tukey-Kramer intervals (0.05) revealed that AR repair had the best percentage difference value for DA [0.5% (P < 0.05)], while the others were not statistically different [L = 27.2%, A = 28.9%, AS = 21.2% (P > 0.05)]. For HC, there was a statistical difference (P < 0.05) between AR and the other techniques for the tooth pairs, 16-26, 11-26 and 21-16; repairs with AR and AS differed for the 11-21 pair, while those with A and AS techniques differed for the 16-26 pair (P < 0.05). The VC differences were not detected between repair methods (P > 0.05). Denture accuracy was not affected by the interaction of base material-repair technique; repair with AR technique gave the best adaptation; the interaction of base material-repair technique did not affect HC; HC was affected by the repair technique.

Risk factors for dopaminergic neuron loss in human alpha-synuclein transgenic mice.

Genetic background, pesticide exposure, age, gender, diet and lifestyle are implicated risk factors in Parkinson's disease. We demonstrate dopamine neuron loss and other features of Parkinsonism based on the interaction of several of these human risk factors in transgenic mice expressing human alpha-synuclein. Mice expressing different forms of human alpha-synuclein had progressive declines in locomotor activity and abnormal responses to apomorphine that were modified by transgenic status. Stereological counts of tyrosine hydroxylase-positive neurons significantly declined with age only in the transgenic lines, consistent with a constant or decreasing risk, with the line expressing a double-mutant form of human alpha-synuclein more severely affected than the line expressing wild-type human alpha-synuclein. Treatment with Mn2+-ethylenebisdithiocarbamate and paraquat resulted in significantly greater effects in the double-mutant line than the other lines. Inclusions were not identified in the transgenic lines. Overexpression of human alpha-synuclein had adverse effects on substantia nigra pars compacta dopaminergic neurons that were modified by risk factors interacting in humans, including human alpha-synuclein mutations, ageing, and exposure to pesticides.

A novel leukoencephalopathy associated with tau deposits primarily in white matter glia.

A 79-year-old woman had a 10-year history of dementia, initially presenting as non-fluent aphasia. Magnetic resonance imaging showed frontal atrophy (left greater than right) and hyperintense foci within white matter. Neuropathologically, there was severe frontal atrophy due to cortical neuronal loss with spongy change and to an even greater loss of white matter that contained prominent eosinophilic deposits. The deposits were immunoreactive for phosphorylated tau, non-reactive for Abeta and alpha-synuclein and equivocally or weakly reactive for ubiquitin. They stained with the Gallyas, Bielschowsky, and Bodian techniques. Ultrastructural examination revealed the deposits to be composed of straight filaments with a diameter of approximately 10 nm, primarily in white matter glia. Moderate loss of neurons in substantia nigra and numerous argyrophilic threads in gray and particularly white matter were noted. The precise relationship between this disorder and other frontotemporal degenerations/tauopathies, as well as the pathogenetic basis of the leukoencephalopathy, remains to be determined.

Differential scanning calorimetric studies of nickel-titanium rotary endodontic instruments after simulated clinical use.

Differential scanning calorimetric (DSC) analyses have been performed between -130 degrees and 100 degrees C on single-segment specimens obtained from ProFile and Lightspeed nickel-titanium rotary endodontic instruments in the as-received condition and after one, three, and six periods of simulated clinical use in extracted teeth. The DSC analyses showed that both brands of instruments were always in the superelastic condition, although the enthalpy values for the transformation from martensitic NiTi to austenitic NiTi were much smaller for the Lightspeed instruments. Simulated clinical use had no evident effect upon this transformation for both brands, which is attributed to insufficient mechanical deformation of the instruments. There were substantial differences in the enthalpy change associated with the transformation from martensitic NiTi to austenitic NiTi for test segments from different positions along the shafts of the instruments and for as-received instruments from two different batches that were analyzed in this study and a previous study. These differences are attributed to variations in work hardening along the shaft during instrument fabrication and to processing differences during production of the two batches of each instrument brand.

Effects of colour measuring mode and light source on the colour of shade guides.

The objectives of this paper were to evaluate the effects of colour measuring modes [specular component excluded (SCE) versus specular component included (SCI)] and the standard light source (C, A or D65) on the colour of shade guides. After the labial part of shade tabs of two shade guides (Vita and Chromascop) was polished flat up to no. 2400 silicone carbide paper, the colour was measured according to the International Commission on Illumination (CIE)L*a*b* colour scale on a spectrophotometer. In both shade guides, all the average CIE L* values of each shade series, and most of CIE b* values were different depending on the measuring mode (P < 0.01). However, there was no difference in CIE a* values depending on the measuring mode. Colour difference (deltaE*) between the values measured with SCE mode and with SCI mode was 3.21-6.50 in Vita shade guide, 3.22-5.47 in Chromascop shade guide. DeltaE* caused by the difference in light source was very small in Vita shade guide regardless of the measuring mode. In the Vita shade guide, the shade series (A-D) was negatively correlated with CIE L* and CIE a* values measured with SCE mode. In the Chromascop shade guide, the shade series (100-500) was negatively correlated with CIE L* value measured with SCI mode.

Differential scanning calorimetric studies of nickel titanium rotary endodontic instruments.

Differential scanning calorimetric (DSC) analyses were performed between -130 degrees and 100 degrees C on specimens prepared from nickel-titanium (NiTi) rotary endodontic instruments: ProFile (n = 5), Lightspeed (n = 4), and Quantec (n = 3). The ProFile and Lightspeed instruments were in the as-received condition, whereas the Quantec instruments were randomly selected from a dental clinic and had unknown history. The DSC plots showed that the ProFile and Lightspeed instruments analyzed had the superelastic NiTi property, with an austenite-finish (Af) temperature of approximately 25 degrees C. Differences in DSC plots for the ProFile instruments and the starting wire blanks (n = 2) were attributed to the manufacturing process. The phase transformation behavior when the specimens were heated and cooled between -130 degrees and 100 degrees C, the temperature ranges for the phase transformations, and the resulting enthalpy changes were similar to those previously reported for nickel-titanium orthodontic wires having superelastic characteristics or shape memory behavior in the oral environment. The experiments demonstrated that DSC is a powerful tool for materials characterization of these rotary instruments, providing direct information not readily available from other analytical techniques about the NiTi phases present, which are fundamentally responsible for their clinical behavior.

Neuropathologic findings in a Guillain-Barré patient with strokes after IVIg therapy.

Strokes have been rarely associated with immunoglobulin G (IVIg) therapy. A 70-year-old woman with stable polycythemia vera developed Guillain-Barré syndrome and received IVIg, 8 days following which she became comatose due to bilaterally symmetric cerebral infarcts. Autopsy showed intravascular aggregates of fibrin-IgG but also platelets and a necrotizing microangiopathy in the infarcts.

Color characteristics of low-chroma and high-translucence dental resin composites by different measuring modes.

The objective of the described research was the evaluation of the effects of the differences in the color-measuring geometry (SCE, SCI) and the standard illuminant on the color and color change after polymerization and thermocycling of resin composites. White, translucent, and conventional shades of two brands of resin composites were measured before and after polymerization and after thermocycling according to the CIE L*a*b* color scale on a reflection spectrophotometer with SCE and SCI geometry under the standard illuminants A, D65, and C. Under both SCE and SCI modes, the color differences (DeltaE*) of specimens between the values measured under illuminants A and D65 or A and C were larger than those between D65 and C in unpolymerized, polymerized, and thermocycled conditions. With SCE geometry, DeltaE* after polymerization of the white shade group was 8.7-9.8 under D65, and was higher than the conventional shade group (p < 0.05) in both materials. With SCE geometry, DeltaE* between polymerized and thermocycled white, translucent shade was 4.4-7.1 under D65. With SCI geometry, the results were in general agreement with those of SCE mode. After polymerization, DeltaE* measured under illuminant A was generally higher than that under D65 or C (p < 0.01). After thermocycling, the color change was different depending on the color-measuring geometry and standard illuminant.

Potential environmental and host participants in the early white matter lesion of adreno-leukodystrophy: morphologic evidence for CD8 cytotoxic T cells, cytolysis of oligodendrocytes, and CD1-mediated lipid antigen presentation.

The 2 most common forms of X-linked adreno-leukodystrophy (ALD) are the juvenile or childhood cerebral form with inflammatory demyelination and the adult adrenomyeloneuropathy (AMN) involving spinal cord tracts without significant inflammation. Modifier genes or environmental factors may contribute to the phenotypic variability. We performed immunohistochemical, an in situ polymerase chain reaction, and TUNEL analyses to identify several viruses, lymphocyte subpopulations, apoptotic cells, and effector molecules, focusing on morphologically normal white matter, dysmyelinative and acute demyelinative lesions. No distinguishing viral antigens were detected. Most lymphocytes were CD8 cytotoxic T cells (CTLs) with the alpha/beta TCR, and they infiltrated morphologically unaffected white matter. Only a few oligodendrocytes were immunoreactive for caspase-3. MHC class II- and TGF-beta-positive microglia were present. CD44, which can mediate MHC-unrestricted target cell death, was seen on many lymphocytes and white matter elements. CD1 molecules, which play major roles in MHC-unrestricted lipid antigen presentation, were noted. Our data indicate that unconventional CD8 CTLs are operative in the early stages of dysmyelination/demyelination and that cytolysis of oligodendrocytes, rather than apoptosis, appears to be the major mode of oligodendrocytic death. The presentation of lipid antigens may be a key pathogenetic element in ALD and AMN-ALD.

Force-deflection properties of superelastic nickel-titanium archwires.

This in vitro study compared the force-deflection behavior of 8 superelastic nickel-titanium orthodontic wires (0.017 x 0.025 in) under controlled moment and temperature. To simulate leveling a lateral incisor, brackets and first molar tubes without tip and angulation were used. The wires (n = 5) were ligated into stainless steel brackets attached to a plastic jig to simulate a mandibular arch. A testing machine (Instron) applied deflections of 0.2 to 2.0 mm at 35 degrees C in the lateral incisor area. Force-deflection diagrams were determined from the passive position to an activation of 2 mm and then during deactivation. Forces on deactivation at a deflection of 1 mm were compared by analysis of variance. Significant differences (P < .05) in forces were observed among wires. All wires exhibited superelastic behavior, but in stratified loading levels.

Dental color standards: shade tab arrangement.

PURPOSE: The aim of this study was to analyze the shade tab arrangement of two popular dental shade guides, suggest possible improvements, and propose clinical guidelines. MATERIALS AND METHODS: Data were recorded using a colorimeter set to standard illuminant source C and CIE L*a*b* system. The manufacturers' shade tab arrangement as well as the possible improvements in the arrangement of shade tabs of Vitapan Classical and Vitapan 3-D Master (Vita Zahnfabrik, Bad Säckingen, Germany) shade guides were examined by regression analysis. RESULTS: Certain shortcomings in the manufacturers' arrangement of both color standards were observed. The Vitapan 3-D Master arrangement was more consistent, but with a decrease in lightness, tab saturation decreased as well in four of its five groups. When Vitapan Classical and Vitapan 3-D Master tabs were arranged according to deltaE* in relation to the lightest tab, r2 was 0.98 and 0.96, respectively. After dividing the total deltaE* range into four equal segments for the newly established Vitapan Classical guide, r2 was 0.91, 0.95, 0.68, and 0.94, respectively. Corresponding r2 values for Vitapan 3-D Master were 0.96, 0.94, 0.90, 0.94, and 1.0. CLINICAL SIGNIFICANCE: Total color difference in relation to the lightest tab, followed by the tab division into an adequate number of groups, is recommended as a possible and universally applicable mode of tab arrangement in dental color standards.

Wear resistance of cryogenically treated stainless steel files.

Cryogenic treatment, which involves ultra-sub-zero treatment of metal alloys, has been shown to improve the wear resistance of several types of stainless steel. The purpose of this study was to examine the effect of cryogenic treatment on wear resistance of Flex-R and Hedstrom (Union Broach) files. These instruments were attached to an Instron testing machine and underwent 300 push-pull strokes (6-mm movement range, 600-mm/min speed, 1-N loading) against 1.5-mm thick dentin wafers. Their wear was determined by comparing the depth of grooves (without changing file position) cut in acrylic specimens (1.5-mm thick) before and after machining dentin. The mean and standard deviation (n = 20) of the relative change in cutting efficiency was determined for the files. An analysis of variance showed that the cutting efficiency of all files decreased significantly after wearing on dentin (p < 0.0001). However, when comparing the post-/pre-cutting efficiency ratios of the files, it was seen that cryogenic treatment did not affect the wear resistance of the files.

Comparison of color of resin composites of white and translucent shades with two shade guides.

PURPOSE: The purpose of this study was to compare the color of resin composites of white, translucent, and conventional shades with shade guides, based on the analysis of the color distribution of shade guides. The influence of color measuring mode, specular component included (SCI) or excluded (SCE), was also determined. MATERIALS AND METHODS: The labial portions of shade guide tabs (Vita and Chromascop) were polished flat with up to 2400-grit SiC paper. Color coordinates were measured according to CIE L*a*b* color scale on a reflection spectrophotometer with both the SCE and SCI modes. The color coordinates of white, translucent, and conventional shades of two brands of resin composites were measured and compared with those of the shade guides. RESULTS: There was no logical order in the color distribution of the two shade guides. The color of white and translucent shades of resin composites was located on the low CIE a* and CIE b* value area. The CIE L*, a*, b* values of resin composite with the same color designations were different, depending on the brand of material. The color difference (deltaE*) of shade guides by the measuring mode (SCE vs. SCI) was between 3.2 and 6.5.