Effect of ambient light and monitor brightness and contrast settings on the detection of approximal caries in digital radiographs: an in vitro study

OBJECTIVES

The aim of this study was to investigate how brightness and contrast settings of the display monitor and ambient light level (illuminance) in the viewing room affect the clinician's ability to diagnose carious lesions in digital radiographs.

METHODS

Standardized radiographs were taken of 100 extracted teeth. Seven observers evaluated the images for approximal carious lesions twice, once under 50 lux and once under 1000 lux room illumination. Monitor brightness and contrast were varied +/-50% and +/-6%, respectively, to mimic the normal limits of monitor adjustment by an inexperienced user and one optimal setting. This was done by adjusting radiograph brightness and contrast by +/-25%. Thus, five radiographs of each tooth were evaluated. Receiver operating characteristic (ROC) analyses were performed. Histological examinations of the teeth served as the criterion standard. A paired t-test was used to evaluate whether differences in the areas under the ROC curves were significant and kappa was used to evaluate intraobserver agreement.

RESULTS

When a monitor with optimal brightness and contrast settings was used to detect approximal carious lesions, ambient light levels less than 50 lux were significantly better than levels above 1000 lux (dentin and enamel lesions, P < 0.01; dentin lesions, P < 0.02). Increasing the contrast setting of the monitor by 6% did not change these results; 50 lux was still significantly better than 1000 lux (enamel lesions, P < 0.01; dentin and enamel lesions, P < 0.02) for evaluating radiographs. Intraobserver agreement differed from fair to good.

CONCLUSIONS

Reducing ambient light to less than 50 lux significantly increased the accuracy of diagnosing approximal carious lesions on a monitor with an optimal brightness setting and an optimal or slightly higher than optimal contrast setting.

Competitive physical activity early in life is associated with bone mineral density in elderly Swedish men

In this population-based study of 75-year-old men (n = 498), we investigated the association between physical activity (PA) early in life and present bone mineral density (BMD). We demonstrate that a high frequency of competitive sports early in life is associated with BMD at several bone sites, indicating that increases in BMD following PA are preserved longer than previously believed.

INTRODUCTION

Physical activity (PA) increases bone mineral density (BMD) during growth. It is unclear if the positive effects remain at old age. In this study, we aimed to determine if PA early in life was associated with BMD in elderly men.

METHODS

In this population-based study, 498 men, 75.2 +/- 3.3 (mean+/-SD) years old, were included. BMD was assessed using DXA. Data concerning lifetime PA, including both competitive (CS) and recreational sports (RS), and occupational physical load (OPL), were collected at interview.

RESULTS

Subjects in the highest frequency group of CS in the early period (10-35 years), had higher BMD at the total body (4.2%, p < 0.01), total hip (7.0%, p < 0.01), trochanter (8.7%, p < 0.01), and lumbar spine (7.9%, p < 0.01), than subjects not involved in CS. A stepwise linear regression model showed that frequency of CS in the early period independently positively predicted present BMD at the total body (beta = 0.12, p < 0.01), total hip (beta = 0.11, p < 0.01), trochanter (beta = 0.12, p < 0.01), and lumbar spine (beta = 0.11, p = 0.01).

CONCLUSIONS

We demonstrate that PA in CS early in life is associated with BMD in 75-year-old Swedish men, indicating that increases in BMD following PA are preserved longer than previously believed.

Single-nucleotide sequence discrimination in situ using padlock probes

Standard fluorescence in situ hybridization (FISH) techniques using cloned probes are limited in their ability to distinguish between closely similar DNA sequences because long hybridization probes are not detectably destabilized by single mismatched base pairs. This problem has been addressed by using short allele-specific oligonucleotide probes whose hybridization to target sequences is more sensitive to mismatches. This revised and expanded unit presents protocols for discrimination between closely similar DNA sequences in situ. The discussion of probe synthesis has been greatly expanded and an Alternate Protocol 1 added for enzymatic probe ligation at low probe concentration. A new Support Protocol describes enzymatic probe synthesis.

Multiplex PCR amplification assay for the detection of blaSHV, blaTEM and blaCTX-M genes in Enterobacteriaceae

Extended-spectrum beta-lactamases (ESBLs) are often mediated by (bla-)SHV, (bla)TEM and (bla)CTX-M genes in Enterobacteriaceae and other Gram-negative bacteria. Numerous molecular typing methods, including PCR-based assays, have been developed for their identification. To reduce the number of PCR amplifications needed we have developed a multiplex PCR assay which detects and discriminates between (bla-)SHV, (bla)TEM and (bla)CTX-M PCR amplicons of 747, 445 and 593 bp, respectively. This multiplex PCR assay allowed the identification of (bla-)SHV, (bla)TEM and (bla)CTX-M genes in a series of clinical isolates of Enterobacteriaceae with previously characterised ESBL phenotype. The presence of (bla)SHV, (bla)TEM and (bla)CTX-M genes was confirmed by partial DNA sequence analysis. Apparently, the universal well-established CTX-M primer pair used here to reveal plasmid-encoded (bla)CTX-M genes would also amplify the chromosomally located K-1 enzyme gene in all Klebsiella oxytoca strains included in the study.

The structural plasticity of heparan sulfate NA-domains and hence their role in mediating multivalent interactions is confirmed by high-accuracy (15)N-NMR relaxation studies

Considering the biological importance of heparan sulfate (HS) and the significant activity of its highly-sulfated regions (S-domains), the paucity of known functions for the non-sulfated NA-domains is somewhat puzzling. It has been suggested that chain dynamics within the NA-domains are the key to their functional role in HS. In this study, we investigate this hypothesis using state-of-the-art nuclear magnetic resonance (NMR) experiments at multiple frequencies. To resolve the problem of severe overlap in (1)H-NMR spectra of repetitive polysaccharides from proteoglycans, we have prepared oligosaccharides with the chemical structure of HS NA-domains containing the (15)N nucleus, which has enough chemical shift dispersion to probe the central residues of octasaccharides at atomic resolution using 600 MHz NMR. By performing NMR relaxation experiments at three magnetic-field strengths, high quality data on internal dynamics and rotational diffusion was obtained. Furthermore, translational diffusion could also be measured by NMR using pulse field gradients. These experimental data were used, in concert with molecular dynamics simulations, to provide information on local molecular shape, greatly aiding our relaxation analyses. Our results, which are more accurate than those presented previously, confirm the higher flexibility of the NA-domains as compared with reported data on S-domains. It is proposed that this flexibility has two functional roles. First, it confers a greater area of interaction from the anchoring point on the core protein for the bioactive S-domains. Secondly, it allows multiple interactions along the same HS chain that are dynamically independent of each other.

Evidence for associations between common polymorphisms of estrogen receptor beta gene with homocysteine and nitric oxide

BACKGROUND

Homocysteine and asymmetric dimethylarginine (ADMA) affect nitric oxide (NO) concentration, thereby contributing to cardiovascular disease (CVD). Both amino acids can be reduced in vivo by estrogen. Variation in the estrogen receptor (ER) may influence homocysteine and ADMA, yet no information is available on associations with single nucleotide polymorphisms in the estrogen receptor genes ERalpha (PvuII and XbaI) and ERbeta (1730G-->A and cx + 56 G-->A).

OBJECTIVE

To find relationships between common polymorphisms associated with cardiovascular disease and cardiovascular risk factors homocysteine and ADMA.

METHODS

In a cross-sectional study with healthy postmenopausal women (n = 89), homocysteine, ADMA, nitric oxide metabolites (NOx), plasma folate and ERalpha and beta polymorphisms ERalpha PvuII, ERalpha XbaI; ERbeta 1730G-->A (AluI), ERbeta cx + 56 G-->A (Tsp509I) were analyzed.

RESULTS

Women who are homozygotic for ERbetacx + 56 G-->A A/A exhibited higher homocysteine (p = 0.012) and NOx (p = 0.056) levels than wildtype or heterozygotes. NOx concentration was also significantly affected by ERbeta 1730 G -->A polymorphism (p = 0.025). The ERbeta (p < 0.001) and ERalpha (p < 0.001) polymorphisms were in linkage disequilibrium.

CONCLUSIONS

Women who are homozygotic for ERbetacx + 56 G-->A A/A may be at increased risk for cardiovascular disease due to higher homocysteine levels.

Differential effects of the N-methyl-d-aspartate receptor antagonist MK-801 on different stages of object recognition memory in mice

The aim of the present study was to evaluate the effects of systemic administration of the N-methyl-d-aspartate (NMDA) receptor antagonist MK-801 on different stages of non-spatial object recognition memory processing in mice. To this end we used the object recognition test, where the animal is tested for its ability to discriminate between an old, familiar, and a novel object. MK-801 (0.1 or 0.2 mg/kg) or saline was administered 1) 30 min before or 2) directly after the first, introductory, session or 3) 30 min before the recognition session. Memory retention was evaluated 1.5 h after the introductory session. MK-801 appeared to decrease memory retention when given prior to the introductory session, but not when given directly after the introductory session or before the recognition session, where MK-801 instead induced an increased interest for the novel object. These results suggest that activation of NMDA receptors is a requisite for encoding of recognition memory in mice but not for consolidation and retrieval processes. The increased interest for the novel object showing up when MK-801 was given directly after the introductory session or before the recognition session may reflect a facilitation of retention. Alternatively, the phencyclidine-like, psychotogenic properties of MK-801 could result in an amplification of the perceived salience of the novel object, and/or anxiolytic mechanisms could result in neophilic effects.

Improved DECRA processing of DOSY data: correcting for non-uniform field gradients

Mixture analysis using PFG-NMR (DOSY) data is, for many chemists, a valuable and increasingly popular technique where the NMR signals of different species are separated according to their diffusion coefficients. Where NMR signals overlap, however, it is often difficult to extract the spectra of pure components from experimental data. In such situations, it can often be helpful to use multivariate methods, which exploit all the available signal covariance, to resolve the spectra of the components of a mixture. The best-established and by some way the quickest such method, DECRA (Direct Exponential Curve Resolution Algorithm), unfortunately requires that data conform to a pure exponential decay as a function of gradient strength squared, while experimental data typically deviate significantly from this. If this deviation is known, the performance of DECRA can be greatly improved for components with similar diffusion coefficients by adjusting the choice of gradient strengths used.

Digital radiography in general dental practice: a field study

OBJECTIVES

The aim of this study was to conduct a field study to survey the performance of digital radiography and how it was used by dentists in general dental practice.

METHODS

19 general dental practitioners were visited at their clinics. Ambient light (illuminance) was measured in the rooms where the monitors were placed. Different technical display parameters were noted. Test images and two phantoms--one low-contrast phantom and one line-pair resolution phantom--were used to evaluate the digital system. How the dentists used the enhancement program was investigated by noting which functions were used.

RESULTS

Average illuminance in the operating room was 668 lux (range 190-1250 lux). On radiographs of the low-contrast phantom taken at the clinic, the ability to observe the holes decreased as illuminance increased. On average, the "light percentage" initially set on the monitor had to be decreased by 17% and contrast by 10% to optimize the display of the test images. The general dental practitioners used the enhancement programs most often to alter brightness and contrast to obtain the subjectively best image. Large differences between the clinics were noted.

CONCLUSION

Knowledge of how to handle digital equipment in general dental practice should be improved. A calibrated monitor of good quality should be a given priority, as should proper ambient light conditions. There is a need to develop standardized quality controls for digital dental radiography.

Early detection of macular changes in patients with diabetes using Rarebit Fovea Test and optical coherence tomography

AIM

To evaluate central retinal thickness and foveal function using optical coherence tomography (OCT) and the Rarebit Fovea Test (RFT) in patients with diabetes without previously known retinopathy or maculopathy.

METHOD

Forty-two patients with diabetes mellitus (DM) were selected from the screening records at St Erik Eye Hospital. Inclusion criteria were absence of macular or other retinal changes at previous screening examination and best corrected visual acuity >/=1.0. These patients and 42 healthy controls were examined with the recently developed RFT, and retinal thickness was measured using OCT. Lens thickness and light scatter were evaluated by Scheimpflug photography.

RESULTS

Significantly more DM subjects (12/42) had a subnormal RFT result compared with the controls (2/42) (p = 0.007). None of the 12 DM subjects had maculopathy, one had mild non proliferative diabetic retinopathy, and five had minimal non-proliferative diabetic retinopathy. The retinal thickness in the pericentral zone was significantly (p<0.05) thinner in DM patients with subnormal RFT compared with the controls.

CONCLUSION

Decreased RT and subnormal RFT results were found in a subgroup of diabetes patients, despite normal screening results. Prospective studies are under way to evaluate the prognostic implications.

Protective and regenerative effects of the GH/IGF-I axis on the brain

Apart from regulating somatic growth and metabolism, evidence suggest that the GH/ IGF-I axis is involved in the regulation of brain growth, development and myelination. Moreover, growth hormone (GH) and particularly IGF-I have been attributed neuroprotective effects in different in vitro and in vivo experimental models. In addition, both GH and IGF-I affect cognition and biochemistry in the adult brain. Some of the effects of GH are suggested to be mediated by circulating IGF-I, while other effects may be due to locally produced IGF-I within the brain. It is also possible that GH may act directly on the central nervous system (CNS) without involving IGF-I (either circulating or locally). Plasticity in the CNS may be viewed as changes in the functional interplay between the major cell types neurons, astrocytes and oligodendrocytes. GH and IGF-I affect all these cell types in several aspects. Apart from neuroprotective effects of GH and IGF-I in different experimental models of CNS injury, IGF-I has been found to increase progenitor cell proliferation and new neurons, oligodendrocytes, and blood vessels in the dentate gyrus of the hippocampus. In the adult cerebral cortex, it appears that only oligodendrogenesis is affected. The increase of IGF-I on endothelial cell phenotype may explain the increase in cerebral arteriole density observed after GH treatment. In the present review, different aspects of the GH/IGF-I axis effects on the brain will be discussed with particular emphasis on neuroprotection, regeneration and brain plasticity. Moreover, recent findings describing neuroprotective effects and effects on synaptic plasticity by GH secretagogues will be reviewed.

Fidelity of an optical memory based on stimulated photon echoes

We investigated the preservation of information encoded into the relative phase and amplitudes of optical pulses during storage and retrieval in an optical memory based on stimulated photon echo. By interfering photon echoes produced in a single-mode Ti:Er:LiNbO(3) waveguide, we found that decoherence in the medium translates only as loss and not as degradation of information. We measured a visibility for interfering echoes close to 100%. These results may have important implications for future long-distance quantum communication protocols.

Pure shift proton DOSY: diffusion-ordered 1H spectra without multiplet structure

The problem of NMR signal overlap in DOSY is significantly diminished by suppressing multiplet structure in the spectral dimension.

Oestrogen receptor alpha gene expression levels are reduced in obese compared to normal weight females

OBJECTIVE

To determine whether oestrogen receptor (ER)alpha messenger RNA (mRNA) levels or single nucleotide polymorphisms (SNPs) are associated with obesity in Swedish women.

DESIGN

ERalpha mRNA expression levels were measured by real-time qPCR in subcutaneous adipose tissue from non-obese (N=16, BMI<30) and obese (N=17, BMI>or=30) women. In addition, ERalpha mRNA expression levels were determined in isolated adipocytes. ERalpha promoter usage was characterized by 5' RACE and by real-time qPCR in subcutaneous adipose tissue from the same non-obese and obese women. Two ERalpha SNPs were scored in 509 non-obese and 489 obese females.

RESULTS

ERalpha mRNA expression levels were lower in obese compared to non-obese women in both subcutaneous adipose tissue and in adipocytes. We show that two ERalpha promoters are differentially utilized in obese and non-obese individuals. We did not find any significant association between obesity and the ERalpha SNPs or haplotypes assayed.

CONCLUSION

The reduced ERalpha mRNA levels observed in adipose tissue from obese compared to non-obese women support a role for oestrogen signaling via ERalpha, in control of body weight. Mechanistic studies of the role of ERalpha in adipocytes and how its expression is regulated in relation to fat mass should be performed. The latter studies should focus on the two promoters that are used differently in obese and non-obese individuals.

The 22q11 deletion syndrome candidate gene Tbx1 determines thyroid size and positioning

Thyroid dysgenesis is the major cause of congenital hypothyroidism in humans. The underlying molecular mechanism is in most cases unknown, but the frequent co-incidence of cardiac anomalies suggests that the thyroid morphogenetic process may depend on proper cardiovascular development. The T-box transcription factor TBX1, which is the most probable gene for the 22q11 deletion syndrome (22q11DS/DiGeorge syndrome/velo-cardio-facial syndrome), has emerged as a central player in the coordinated formation of organs and tissues derived from the pharyngeal apparatus and the adjacent secondary heart field from which the cardiac outflow tract derives. Here, we show that Tbx1 impacts greatly on the developing thyroid gland, although it cannot be detected in the thyroid primordium at any embryonic stage. Specifically, in Tbx1-/- mice, the downward translocation of Titf1/Nkx2.1-expressing thyroid progenitor cells is much delayed. In late mutant embryos, the thyroid fails to form symmetric lobes but persists as a single mass approximately one-fourth of the normal size. The hypoplastic gland mostly attains a unilateral position resembling thyroid hemiagenesis. The data further suggest that failure of the thyroid primordium to re-establish contact with the aortic sac is a key abnormality preventing normal growth of the midline anlage along the third pharyngeal arch arteries. In normal development, this interaction may be facilitated by Tbx1-expressing mesenchyme filling the gap between the pharyngeal endoderm and the detached thyroid primordium. The findings indicate that Tbx1 regulates intermediate steps of thyroid development by a non-cell-autonomous mechanism. Thyroid dysgenesis related to Tbx1 inactivation may explain an overrepresentation of hypothyroidism occurring in patients with the 22q11DS.

Nuclear and mitochondrial DNA quantification of various forensic materials

Due to the different types and quality of forensic evidence materials, their DNA content can vary substantially, and particularly low quantities can impact the results in an identification analysis. In this study, the quantity of mitochondrial and nuclear DNA was determined in a variety of materials using a previously described real-time PCR method. DNA quantification in the roots and distal sections of plucked and shed head hairs revealed large variations in DNA content particularly between the root and the shaft of plucked hairs. Also large intra- and inter-individual variations were found among hairs. In addition, DNA content was estimated in samples collected from fingerprints and accessories. The quantification of DNA on various items also displayed large variations, with some materials containing large amounts of nuclear DNA while no detectable nuclear DNA and only limited amounts of mitochondrial DNA were seen in others. Using this sensitive real-time PCR quantification assay, a better understanding was obtained regarding DNA content and variation in commonly analysed forensic evidence materials and this may guide the forensic scientist as to the best molecular biology approach for analysing various forensic evidence materials.

Apoptosis-inducing factor is a major contributor to neuronal loss induced by neonatal cerebral hypoxia-ischemia

Nine-day-old harlequin (Hq) mice carrying the hypomorphic apoptosis-inducing factor (AIF)(Hq) mutation expressed 60% less AIF, 18% less respiratory chain complex I and 30% less catalase than their wild-type (Wt) littermates. Compared with Wt, the infarct volume after hypoxia-ischemia (HI) was reduced by 53 and 43% in male (YX(Hq)) and female (X(Hq)X(Hq)) mice, respectively (P<0.001). The Hq mutation did not inhibit HI-induced mitochondrial release of cytochrome c or activation of calpain and caspase-3. The broad-spectrum caspase inhibitor quinoline-Val-Asp(OMe)-CH(2)-PH (Q-VD-OPh) decreased the activation of all detectable caspases after HI, both in Wt and Hq mice. Q-VD-OPh reduced the infarct volume equally in Hq and in Wt mice, and the combination of Hq mutation and Q-VD-OPh treatment showed an additive neuroprotective effect. Oxidative stress leading to nitrosylation and lipid peroxidation was more pronounced in ischemic brain areas from Hq than Wt mice. The antioxidant edaravone decreased oxidative stress in damaged brains, more pronounced in the Hq mice, and further reduced brain injury in Hq but not in Wt mice. Thus, two distinct strategies can enhance the neuroprotection conferred by the Hq mutation, antioxidants, presumably compensating for a defect in AIF-dependent redox detoxification, and caspase inhibitors, presumably interrupting a parallel pathway leading to cellular demise.

Correction of systematic errors in CORE processing of DOSY data

DOSY data for mixtures are commonly processed either by single channel methods (e.g. HR-DOSY) or multichannel methods (e.g. CORE). Both aim to separate the signals from species of different molecular sizes by their diffusion coefficients; the result is displayed either as a 2D plot (as in HR-DOSY) or as individual spectra (as in CORE). Both types of methods are sensitive to any systematic errors in the experimental data. The effects of, and remedies for, two such sources of error, spatially non-uniform pulsed field gradients (PFGs) and instrument instability, are demonstrated for CORE processing, using a corrected form of the Stejskal-Tanner equation and reference deconvolution, respectively.