Metagenomic next-generation sequencing vs. conventional detection methods for detecting the pulmonary infections

OBJECTIVE

The absence of proper pathogen treatment in the early stages can result in missing out on treatment chances or the overuse of antibiotics, both of which are the primary factors behind fatalities caused by lung infections. In this study, we aimed to investigate the efficacy of metagenomic next-generation sequencing (mNGS) in comparison to conventional detection methods in detecting infectious pathogens.

PATIENTS AND METHODS

In this retrospective study, the infection pathogens of 104 patients were examined, and 86 bronchoalveolar lavage fluid (BALF), eight pleural effusions, and ten sputum samples were collected. The conventional detection approaches and mNGS analysis were used to determine the infection pathogen profiles and their detection rates were analyzed.

RESULTS

Our study showed that mNGS was more sensitive (89.42%) than the conventional detection methods (56.73%) (p < 0.001), with a 32.69% improvement in sensitivity. The efficacy of mNGS in detecting mixed infections was significantly higher than that of conventional detection methods, with a detection rate of 85.29% compared to 17.65% (p < 0.001). The study demonstrated that mNGS had a higher sensitivity than the conventional detection methods when it came to diagnosing pulmonary infections, making it a potentially useful tool for clinical diagnosis.

CONCLUSIONS

Combining mNGS with other pathogenic detection techniques can be an effective way to increase the rate of detecting pulmonary infections, as well as to provide guidance for treatment adjustments. Furthermore, the timing of sample collection and antibiotic administration can influence the effectiveness of mNGS when used on BALF specimens.

In children and adolescents with temporomandibular disorder assembled with juvenile idiopathic arthritis - no association were found between pain and TMJ deformities using CBCT

Background

Children and adolescents with juvenile idiopathic arthritis (JIA) may suffer from temporomandibular disorder (TMD). Due to this, imaging diagnosis is crucial in JIA with non-symptomatic TM joint (TMJ) involvement. The aim of the study was to examine the association between clinical TMD signs/symptoms and cone-beam computed tomography (CBCT) findings of TMJ structural deformities in children and adolescents with JIA.

Methods

This cross-sectional study is part of a longitudinal prospective multi-centre study performed from 2015–2020, including 228 children and adolescents aged 4–16 years diagnosed with JIA, according to the International League of Associations for Rheumatology (ILAR). For this sub-study, we included the Bergen cohort of 72 patients (32 female, median age 13.1 years, median duration of JIA 4.5 years). Clinical TMD signs/symptoms were registered as pain on palpation, pain on jaw movement, and combined pain of those two. The severity of TMJ deformity was classified as sound (no deformity), mild, or moderate/severe according to the radiographic findings of CBCT.

Results

Of 72 patients, 21 (29.2%) had pain on palpation at and around the lateral pole, while 41 (56.9%) had TMJ pain upon jaw movement and 26 (36.1%) had pain from both. Of 141 TMJs, 18.4% had mild and 14.2% had moderate/severe structural deformities visible on CBCT. CBCT findings were not significantly associated with either the pain on palpation or the pain on jaw movement. A significant difference was found between structural deformities in CBCT and the combined pain outcome (pain at both palpation and movement) for both TMJs for the persistent oligoarticular subtype (p = 0.031).

Conclusions

There was no association between painful TMD and CBCT imaging features of the TMJ in patients with JIA, but the oligoarticular subtype of JIA, there was a significant difference associated with TMJ pain and structural CBCT deformities.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-021-01870-z.

Prevalence of temporomandibular disorder in children and adolescents with juvenile idiopathic arthritis - a Norwegian cross- sectional multicentre study

Background

Children and adolescents with juvenile idiopathic arthritis (JIA) may suffer pain from temporomandibular disorder (TMD). Still, routines for the assessment of temporomandibular joint (TMJ) pain in health and dental care are lacking. The aims of this study were to examine the prevalence of TMD in children and adolescents with JIA compared to their healthy peers and to investigate potential associations between JIA and TMD.

Methods

This comparative cross-sectional study is part of a longitudinal multicentre study performed during 2015–2020, including 228 children and adolescents aged 4–16 years with a diagnosis of JIA according to the ILAR criteria. This particular substudy draws on a subset of data from the first study visit, including assessments of TMD as part of a broader oral health examination. Children and adolescents with JIA were matched with healthy controls according to gender, age, and centre site. Five calibrated examiners performed the clinical oral examinations according to a standardised protocol, including shortened versions of the diagnostic criteria for TMD (DC/TMD) and the TMJaw Recommendations for Clinical TMJ Assessment in Patients Diagnosed with JIA. Symptoms were recorded and followed by a clinical examination assessing the masticatory muscles and TMJs.

Results

In our cohort of 221 participants with JIA and 221 healthy controls, 88 (39.8%) participants with JIA and 25 (11.3%) healthy controls presented with TMD based on symptoms and clinical signs. Painful TMD during the last 30 days was reported in 59 (26.7%) participants with JIA vs. 10 (5.0%) of the healthy controls (p <  0.001). Vertical unassisted jaw movement was lower in participants with JIA than in controls, with means of 46.2 mm vs. 49.0 mm, respectively (p <  0.001). Among participants with JIA, a higher proportion of those using synthetic disease-modifying antirheumatic-drugs and biologic disease-modifying antirheumatic-drugs presented with painful masticatory muscles and TMJs at palpation.

Conclusion

Symptoms and clinical signs of TMD were seen in approximately half of the JIA patients compared to about one fourth of their healthy peers. Painful palpation to masticatory muscles and decreased vertical unassisted jaw movement were more frequent in participants with JIA than among healthy controls and should be part of both medical and dental routine examinations in patients with JIA.

[Design and application of static progressive ankle foot orthosis]

The scar contracture of Achilles tendon in burn patients after operation is easy to cause " foot drop" , which leads to ankle dorsiflexion dysfunction. To solve this problem, the authors designed and made a static progressive ankle foot orthosis. The foot support part and the crus support part of the orthotic device are connected by rivets, and the distal end of the foot support part and the proximal end of the crus support part are pulled by the traction belt on both sides, gradually improving the ankle dorsiflexion function. This static progressive ankle foot orthosis is simple, practical, cost-effective, and worthy of clinical promotion.

[Nursing strategies for the facial skin injuries caused by wearing medical-grade protective equipment]

For effective resistance to virus attack and infection and reducing virus transmission chance, it is extremely important for the medical staff and related workers to have their own safe protection. The paper summarizes the occurrence causes, common locations, and prevention ways about the device related pressure ulcers on the face resulted from wearing medical-grade protective equipment for a long working time. The paper proposes the prevention and nursing strategies for device related pressure ulcers and other related skin injuries during application of medical-grade protective equipment. The paper aims to provide reference for the prevention and nursing of device related pressure ulcers and related skin diseases for clinical medical staff, especially to the respectable personnel in front line of fighting against coronavirus disease 2019.

[Application of low temperature thermoplastic plate combined with special abdominal band in fixing abdominal pedicled flap for repairing 17 patients with deep electric burn wounds in hands]

If the abdominal pedicled flaps are not well fixed after repair of deep electric burn wounds in hands, many problems such as poor blood supply may occur. In order to solve the above problems, we designed and manufactured the individualized low temperature thermoplastic plate combined with special abdominal band to fix abdominal pedicled flaps for repairing of 17 patients (12 males and 5 females, aged 2-35 years) with deep electric burn wounds in hands from February 2016 to August 2018, and achieved the desired results. The shoulder joint, elbow joint, and wrist joint were fixed by low temperature thermoplastic plate according to the 1/2 circumference of the patient's side chest and upper arm, and the braking of wrist joint and elbow joint was strengthened by special abdominal band. Application of the combined method of fixing abdominal pedicled flaps in repairing deep electric burn wounds in hands has high success rate of flap transplantation. It is simple to make and practical, and worthy of clinical promotion.

[Influences of follow-up methods on rehabilitation and compliance of patients with severe scar after burns]

Objective: To observe the influences of different follow-up methods on rehabilitation and compliance of patients with severe scar after burns. Methods: From January 2012 to May 2016, medical records of 116 patients with severe scar after burns who were admitted to our unit, discharged after wound healing and conforming to the criteria, were retrospectively analyzed. They were divided into face-to-face follow-up group [n=59, 45 males and 14 females, aged (36±9) years] and routine follow-up group [n=57, 44 males and 13 females, aged (35±9) years] based on different follow-up methods they received. On the day of discharge and in post discharge month (PDM) 1, 3, and 6, the Vancouver Scar Scale (VSS) was used to evaluate the hypertrophic scar in joints, Activities of Daily Living (ADL) scale was used to evaluate the disability of patients in the 2 groups. In PDM 1, 3, and 6, Medical Compliance Behavior Questionnaire was used to investigate the medical compliance behaviors of patients in the 2 groups. Data were processed with chi-square test, t test with Bonferroni correction, and analysis of variance for repeated measurement. Results: (1) The VSS score of patients in face-to-face follow-up group on the day of discharge was (11.1±0.7) points, which was close to (11.7±0.7) points of routine follow-up group (t=2.021, P>0.05). The VSS scores of patients in face-to-face follow-up group in PDM 1, 3, and 6 were (10.5±0.6), (8.6±0.7), and (4.7±0.5) points, which were significantly lower than (11.4±0.7), (10.9±1.0), and (9.4±0.8) points of routine follow-up group respectively (t=2.034, 2.033, 2.042, P<0.05 or P<0.01). (2) The ADL score of patients in face-to-face follow-up group on the day of discharge was close to that of routine follow-up group (t=1.781, P>0.05). The ADL scores of patients in face-to-face follow-up group in PDM 1, 3, and 6 were higher than those of routine follow-up group respectively (t=9.683, 8.584, 9.772, P<0.01). (3) The compliance rates of consisted rehabilitation, reasonable diet, and timing consultation of patients in face-to-face follow-up group were better than those of routine follow-up group respectively (χ(2)=19.015, 13.251, 8.652, P<0.01). Conclusions: Compared with routine follow-up by phone, face-to-face follow-up can do better in evaluating the scar condition and ADL of patients with severe scar after burns, and improve the medical compliance rates of patients, which is worthy of clinical promotion.

[Observation on the effects of multidisciplinary comprehensive intervention in integrated treatment of patients with extremely severe burns]

Objective: To explore the effects of multidisciplinary comprehensive intervention in integrated treatment of patients with extremely severe burns. Methods: One hundred and ten patients hospitalized in our center from July 2013 to August 2017 met the criteria for inclusion in this study, and their medical records were retrospectively analyzed. According to the medical model at that time, 56 patients hospitalized from July 2013 to July 2015 received routine comprehensive treatment led by doctors, and they were included in the conventional intervention group. From August 2015 to August 2017, 54 patients were treated with integrated multidisciplinary interventions performed by a team consisting of physicians, intensive care nurses, burn nurses, intravenous infusion nurses, wound stoma nurses, and rehabilitation therapists, and they were included in the integrated intervention group. Acute Physiological and Chronic Health Assessment Ⅱ (APACHE Ⅱ) scores on admission and 4 weeks after treatment, incidences of pressure injury, wound sepsis, lung infection, and catheter-related infection during hospitalization, length of stay in intensive care unit (ICU) and total length of hospital stay, and Abbreviated Burn Specific Health Scale (BSHS-A) scores at discharge and 3 months after discharge were analyzed. Data were processed with t-test and chi-square test. Results: The APACHE Ⅱ scores of patients in the two groups were close on admission (t=0.573, P>0.05). Four weeks after treatment, the APACHE Ⅱ scores of patients in the two groups were obviously lower than those on admission within the same group (t=5.697, 4.853, P<0.01), and the score of the integrated intervention group was obviously lower than that of the conventional intervention group (t=2.170, P<0.05). No pressure injury was observed in patients of any group during hospitalization. The incidences of wound sepsis, lung infection, and catheter-related infection of patients in the integrated intervention group were 18.5% (10/54), 3.7% (2/54), and 9.3% (5/54), respectively, significantly lower than 42.9% (24/56), 21.4% (12/56), and 26.8% (15/56) of the conventional intervention group, χ²=4.073, 6.075, 3.962, P<0.05. The length of stay in ICU of patients in the integrated intervention group was (50±5) d, obviously shorter than (62±4) d of the conventional intervention group (t=2.852, P<0.01). The total length of hospital stay of patients in the integrated intervention group was (115±8) d, obviously shorter than (140±7) d of the conventional intervention group (t=16.885, P<0.01). At discharge and 3 months after discharge, the scores of BSHS-A, physical function, psychological function, and general health status of 50 patients in the integrated intervention group were significantly higher than those of 48 patients in the conventional intervention group (t=2.886, 3.126, 2.416, 2.544, 2.033, 3.471, 2.588, 2.210, P<0.05 or P<0.01), while the scores of social function of patients in the two groups were close (t=1.570, 1.350, P>0.05). Conclusions: Integrative treatment of patients with extremely severe burns by multidisciplinary comprehensive intervention can significantly alleviate the severity of burns, reduce the incidences of wound sepsis, lung infection, and catheter-related infection, shorten the length of stay in ICU and total length of hospital stay, and improve the quality of life.

[A case of schwannoma in cervical trachea]

Primary tracheal schwannoma is rare. It is easy to be misdiagnosed as bronchitis, asthma due to the lack of special symptom. Diagnosis of schwannoma depends on a comprehensive examination. Surgery is the only effective mean. Here we reported a 17-year-old male, who suffered from cough for 10 months. A variety of tests confirmed that he had schwannoma. There is no significant change after tumor resection via rigid bronchoscope since two years ago.

Self-Propelled Particles with Velocity Reversals and Ferromagnetic Alignment: Active Matter Class with Second-Order Transition to Quasi-Long-Range Polar Order

We introduce and study in two dimensions a new class of dry, aligning active matter that exhibits a direct transition to orientational order, without the phase-separation phenomenology usually observed in this context. Characterized by self-propelled particles with velocity reversals and a ferromagnetic alignment of polarities, systems in this class display quasi-long-range polar order with continuously varying scaling exponents, yet a numerical study of the transition leads to conclude that it does not belong to the Berezinskii-Kosterlitz-Thouless universality class but is best described as a standard critical point with an algebraic divergence of correlations. We rationalize these findings by showing that the interplay between order and density changes the role of defects.

Phytoremediation of soils contaminated with phenanthrene and cadmium by growing willow (Salix × aureo-pendula CL 'j1011')

To assess the phytoremediation potential of an autochthonous willow (Salix × aureo-pendula CL 'J1011') for phenanthrene (PHE)-contaminated soils and PHE-cadmium (PHE-Cd) co-contaminated soils, we conducted field experiments in the lower reaches of the Yangtze River, China. Ethylenediaminetetraacetic acid (EDTA) and ethyl lactate were tested for individual and combined effects on the phytoremediation efficiency. For PHE-contaminated soils, willow plus ethyl lactate resulted in significant removal of PHE from soils after 45 days, and the PHE concentration in the shoots was significantly higher with than without ethyl lactate. For PHE-Cd co-contaminated soils, both willow plus EDTA and willow plus EDTA and ethyl lactate led to a significant decrease in the concentrations of PHE and Cd in the soils after 45 days, whereas willow alone did not. The PHE and Cd concentrations in the willow shoots were significantly enhanced in the presence of EDTA alone and with ethyl lactate, except for the PHE concentration in stems with EDTA alone. Under the same treatment, the presence of Cd had no significant influence on the PHE removal from soils. The results indicate the feasibility of using this willow together with both EDTA and ethyl lactate for the simultaneous removal of PHE and Cd from soils.

Evaluation of the effective dose of cone beam CT and multislice CT for temporomandibular joint examinations at optimized exposure levels

OBJECTIVES

To compare the effective dose to patients from temporomandibular joint examinations using a dental CBCT device and a multislice CT (MSCT) device, both before and after dose optimization.

METHODS

A Promax(®) 3D (Planmeca, Helsinki, Finland) dental CBCT and a LightSpeed VCT(®) (GE Healthcare, Little Chalfont, UK) multislice CT were used. Organ doses and effective doses were estimated from thermoluminescent dosemeters at 61 positions inside an anthropomorphic phantom at the exposure settings in clinical use. Optimized exposure protocols were obtained through an optimization study using a dry skull phantom, where four observers rated image quality taken at different exposure levels. The optimal exposure level was obtained when all included criteria were rated as acceptable or better by all observers.

RESULTS

The effective dose from a bilateral examination was 184 µSv for Promax 3D and 113 µSv for LightSpeed VCT before optimization. Post optimization, the bilateral effective dose was 92 µSv for Promax 3D and 124 µSv for LightSpeed VCT.

CONCLUSIONS

At optimized exposure levels, the effective dose from CBCT was comparable to MSCT.

Oxygen vacancy diffusion in bare ZnO nanowires

Oxygen vacancies (VO) are known to be common native defects in zinc oxide (ZnO) and to play important roles in many applications. Based on density functional theory, we present a study for the migration of oxygen vacancies in ultra-thin ZnO nanowires (NWs). We find that under equilibrium growth conditions VO has a higher formation energy (Ef) inside the wire than that at shallow sites and surface sites, with different geometric relaxations and structural reconstructions. The migration of VO has lower barriers in the NW than in the bulk and is found to be energetically favorable in the direction from the bulk to the surface. These results imply a higher concentration of VO at surface sites and also a relative ease of diffusion in the NW structure. Our results support the previous experimental observations and are important for the development of ZnO-based devices in photocatalysis and optoelectronics.

The P450 enzyme Shade mediates the hydroxylation of ecdysone to 20-hydroxyecdysone in the Colorado potato beetle, Leptinotarsa decemlineata

Ecdysone 20-monooxygenase (E20MO), a cytochrome P450 monooxygenase (CYP314A1), catalyses the conversion of ecdysone (E) to 20-hydroxyecdysone (20E). We report here the cloning and characterization of the Halloween gene Shade (Shd) encoding E20MO in the Colorado potato beetle, Leptinotarsa decemlineata. LdSHD has five conserved motifs typical of insect P450s, ie the Helix-C, Helix-I, Helix-K, PxxFxPE/DRF (PERF) and heme-binding motifs. LdShd was expressed in developing eggs, the first to fourth instars, wandering larvae, pupae and adults, with statistically significant fluctuations. Its mRNA was ubiquitously distributed in the head, thorax and abdomen. The recombinant LdSHD protein expressed in Spodoptera frugiperda 9 (Sf9) cells catalysed the conversion of E to 20E. Dietary introduction of double-stranded RNA (dsRNA) of LdShd into the second instar larvae successfully knocked down the LdShd expression level, decreased the mRNA level of the ecdysone receptor (LdEcR) gene, caused larval lethality, delayed development and affected pupation. Moreover, ingestion of LdShd-dsRNA by the fourth instars also down-regulated LdShd and LdEcR expression, reduced the 20E titre, and negatively influenced pupation. Introduction of 20E and a nonsteroidal ecdysteroid agonist halofenozide into the LdShd-dsRNA-ingested second instars, and of halofenozide into the LdShd-dsRNA-ingested fourth instars almost completely relieved the negative effects on larval performance. Thus, LdSHD functions to regulate metamorphotic processes by converting E to 20E in a coleopteran insect species Le. decemlineata.

Application of contrast-enhanced ultrasonography in the diagnosis of skeletal muscle crush injury in rabbits

OBJECTIVE

To explore the diagnostic value of quantitative contrast-enhanced (CE) ultrasonography for crush injury in the hind limb muscles of rabbits.

METHODS

A total of 120 New Zealand white rabbits were randomized to receive compression on the left hind limb for either 2 h (n = 56) or 4 h (n = 56) to induce muscle crush injury. Another eight animals were not injured and served as normal controls. CE ultrasonography parameters such as peak intensity (PI), ascending slop, descending slop and area under curve (AUC) were measured at 0.5, 2, 6 and 24 h and 3, 7 and 14 days after decompression.

RESULTS

Compared with the uninjured muscles, reperfusion of the injured muscles showed early and high enhancement in CE ultrasonography images. The time-intensity curve showed a trend of rapid lift and gradual drop. The PI and AUC values differed significantly among the three groups and were positively correlated with serum and tissue biomarkers. Rabbits of the 4-h compression group showed significantly higher PI and AUC values, and serum and tissue parameters than the 2-h compression group at each time points.

CONCLUSION

CE ultrasonography can effectively detect muscle crush injury and monitor dynamic changes of the injured muscles in rabbits. PI and AUC are promising diagnostic parameters for this disease.

ADVANCES IN KNOWLEDGE

CE ultrasonography might play an important role in the pre-hospital and bedside settings for the diagnosis of muscle crush injury.

Risk prognosis factors of chronic subdural hematoma evacuated by the novel YL-1 hollow needle aspiration drainage system

AIM

The novel YL-1 hollow needle aspiration drainage system is an effective minimally invasive treatment in chronic subdural hematoma (CSDH). In order to find the risk prognosis factors of chronic subdural hematoma (CSDH) performed by the novel YL-1 hollow needle aspiration drainage system, a logistic analysis of postoperative results was performed.

METHODS

One hundred ninety-four cases of chronic subdural hematoma in a period of 7 years since 2004 were collected. According to the postoperative rehabilitation effect of nerve function, the patients were divided into good prognosis group and poor prognosis group. The patients' indexes of the two groups with age, blood coagulation function, location of the hematoma, hematoma volume, admission Markwalder's grade, clinical symptoms were tested by the chi-square test, then the statistically significant factors were selected into the establishment of the Logistic regression model and further analysis of multiple factors were made on chronic subdural hematoma prognostic implications.

RESULTS

Retrospective analysis was performed for differentiating good prognosis group (N.=174) and poor prognosis group (N.=20). Univariate analysis after the chi-square test showed that there were significant differences in gender, age, coagulation function, hematoma position, hematoma size, initial Markwalder's neurological grade, clinical symptoms and signs. Logistic regression analysis showed that chronic subdural hematoma prognostic factors sorted by odds ratio were as follows: high Markwalder's grade, male, coagulopathy, bilateral hematoma, senior citizens.

CONCLUSION

We used logistic regression analysis to identify the risk prognosis factors of chronic subdural hematoma (CSDH) performed by a novel YL-1 hollow needle aspiration drainage systems, and found that high preoperative Markwalder's gradie, male, coagulopathy, bilateral hematoma, senior citizens will poorly affect prognosis in CSDH.

Comparison of psychophysical properties of two intraoral digital sensors on low-contrast perceptibility

OBJECTIVES

The psychophysical properties of a new complementary metal oxide semi-conductor-based detector, ProSensor(®) (Planmeca Oy, Helsinki, Finland), in terms of dose response function and perceptibility curve test were performed and compared with those of a charged couple device-based sensor, Dixi(®) (Planmeca Oy).

METHODS

Dose response functions at 66 kVp for a Dixi and a ProSensor were determined by means of multiple exposures to a homogeneous X-ray field covering the whole exposure range. The entry dose of each exposure was measured and registered. The mean grey level in each image was plotted as function of the corresponding exposures for both digital systems. Radiographs of a test object containing ten holes of increasing depth were obtained throughout the exposure range of the two digital sensors at 66 kVp. 12 observers were asked to register the number of perceptible holes in each radiograph. Based on the mean value of the observers' evaluation, the perceptibility curves were constructed, and the integral value under the perceptibility curves were compared between two intraoral sensors.

RESULTS

The results based on dose response function showed that the ProSensor was more sensitive than the Dixi sensor. Paired t-test showed that the minimal perceptible low-contrast details were significantly higher for the ProSensor than for the Dixi sensor (p < 0.001). The integrals below the two perceptibility curves were 33.4 and 69.2 for the Dixi and ProSensor, respectively.

CONCLUSION

Applying the new ProSensor may be beneficial to patients owing to its reduced radiation dose and increased perception for low-contrast details in dentistry.

Detection accuracy of condylar bony defects in Promax 3D cone beam CT images scanned with different protocols

OBJECTIVES

To investigate and compare the detection accuracy of bony defects on the condylar surface of the temporomandibular joint (TMJ) in cone beam CT (CBCT) images scanned with standard and large view protocols on the same machine.

METHODS

21 dry human skulls with 42 TMJs were scanned with the large view and standard view protocols of the CBCT scanner Promax 3D (Planmeca, Helsinki, Finland). Seven observers evaluated all the images for the presence or absence of defects on the surface of the condyle. Using the macroscopic examination of condylar defects as the gold standard, receiver operating characteristic (ROC) analysis was performed.

RESULTS

Macroscopic examination revealed that, of the 42 condyles, 18 were normal and 24 had a defect on the surface of the condyles. Areas under the ROC curves for the large view and the standard view group of CBCT images were 0.739 and 0.720, respectively, and no significant difference was found between the two groups of images (p = 0.902). Neither the interobserver nor the intraobserver variability were significant.

CONCLUSIONS

The two scanning protocols provided by the CBCT scanner Promax 3D were reliable and comparable with detection of condylar defects.

Comparison of psychophysical properties of two intraoral digital sensors on low-contrast perceptibility

OBJECTIVES

The psychophysical properties of a new complementary metal oxide semi-conductor-based detector, ProSensor® (Planmeca Oy, Helsinki, Finland), in terms of dose response function and perceptibility curve test were performed and compared with those of a charged couple device-based sensor, Dixi® (Planmeca Oy).

METHODS

Dose response functions at 66 kVp for a Dixi and a ProSensor were determined by means of multiple exposures to a homogeneous X-ray field covering the whole exposure range. The entry dose of each exposure was measured and registered. The mean grey level in each image was plotted as function of the corresponding exposures for both digital systems. Radiographs of a test object containing ten holes of increasing depth were obtained throughout the exposure range of the two digital sensors at 66 kVp. 12 observers were asked to register the number of perceptible holes in each radiograph. Based on the mean value of the observers' evaluation, the perceptibility curves were constructed, and the integral value under the perceptibility curves were compared between two intraoral sensors.

RESULTS

The results based on dose response function showed that the ProSensor was more sensitive than the Dixi sensor. Paired t-test showed that the minimal perceptible low-contrast details were significantly higher for the ProSensor than for the Dixi sensor (p < 0.001). The integrals below the two perceptibility curves were 33.4 and 69.2 for the Dixi and ProSensor, respectively.

CONCLUSION

Applying the new ProSensor may be beneficial to patients owing to its reduced radiation dose and increased perception for low-contrast details in dentistry.

Optimal electron doping of a C60 monolayer on Cu(111) via interface reconstruction

We demonstrate the charge state of C60 on a Cu(111) surface can be made optimal, i.e., forming C60(3-) as required for superconductivity in bulk alkali-doped C60, purely through interface reconstruction rather than with foreign dopants. We link the origin of the C60(3-) charge state to a reconstructed interface with ordered (4x4) 7-atom vacancy holes in the surface. In contrast, C60 adsorbed on unreconstructed Cu(111) receives a much smaller amount of electrons. Our results illustrate a definitive interface effect that affects the electronic properties of molecule-electrode contact.

Ab Initio Electron Transport Study of Carbon and Boron−Nitrogen Nanowires

We report first-principles calculations on the electrical transport properties of two kinds of one-dimensional nanowires: (a) a carbon nanowire (CNW) with alternating single and triple bonds and (b) a boron-nitrogen nanowire (BNNW) with equidistant bonds. We demonstrate the similarity and difference between the carbon nanowire and its boron-nitrogen analogue in the molecular orbital and transport properties, and then explore the potential innovations. The effects of molecular orbitals and nanowire-electrode coupling on the transport properties are analyzed. The cases of the nanowires sandwiched between both nanoscale and bulk electrodes are considered. It suggests that the characteristics of the transmission spectra and the current-voltage characteristics (I-V curves) are determined both by the electrodes and by the molecule as well as their coupling. In particular, the negative differential resistance (NDR) phenomenon is more apparent when the nanowires are positioned between two nanoscale electrodes. The tuning of the transport properties is also probed through the changes of nanowire-electrode separation and the inclusion of a gate voltage. These lead to dramatic variations in the equilibrium conductance, which can be understood from the shift and alignment of the molecular orbital relative to the Fermi level of the electrodes. In the analysis of the effects of nanowire-electrode separation, it shows that the equilibrium conductance has the same variation behavior as that of the projected density of states (PDOS) for CNW, while the localized molecular orbitals of BNNW result in its conductance varies differently from its PDOS. The different molecular orbital characteristics near the Fermi level of these two kinds of nanowires underlie their different transport properties.

Perceptibility curve test for conventional and colour-coded radiographs

OBJECTIVE

A colour scale has been developed as a complement to the grey scale in radiographs. The aim of the present study was to compare colour-coded with conventional black-and-white radiographs in terms of the perceptibility curve test.

MATERIALS AND METHODS

Twelve digital radiographs were exposed on a test object from low to high exposures and recorded using the DIXI system (Planmeca Oy, Helsinki, Finland). An aluminium test object was used containing ten object details in the form of holes with depths ranging from 0.03 mm to 0.30 mm in steps of 0.03+/-0.01 mm. The new colour scale was used to transform the conventional black-and-white radiographs into colour radiographs by specially designed software. Ten observers were asked to analyse four sets of radiographs, i.e. colour-coded and black-and-white radiographs, and reversed colour-coded and reversed black-and-white radiographs. The object detail having the lowest perceptible contrast in each radiograph was registered for each observer. Perceptibility curves were plotted based on the mean value of observer data.

RESULTS

Results from the perceptibility curve test showed that the information in colour-coded radiographs was at least as good as that in black-and-white radiographs. In fact, in the lower exposure range, colour-coded radiographs exhibited better perception than conventional black-and-white radiographs.

CONCLUSION

Radiographs that are colour-coded with the applied colour scale may be used as an alternative to conventional black-and-white radiographs.

Comparison of the psychophysical properties of various intraoral film and digital systems by means of the perceptibility curve test

OBJECTIVES

To compare psychophysical properties of two intraoral films and three digital systems using the perceptibility curve (PC) test.

MATERIALS AND METHODS

A test object was used to determine the exposures and exposure differences between the total thickness of the test object and details consisting of holes of increasing depth. The PCs for the two intraoral films, UltraSpeed and EktaSpeed Plus, were constructed employing exposure and exposure differences from dose response functions. Integrals of the PCs were calculated to obtain the psychophysical properties of the two films. Psychophysical properties of the two films were compared with those of the three digital systems published previously (CDR, Dixel and Digora).

RESULTS

The PC for the EktaSpeed Plus showed a slightly higher peak than that for the UltraSpeed. Available exposure ranges were comparable. The PC for the EktaSpeed Plus was shifted to the left of the exposure axis indicating its higher sensitivity as compared with UltraSpeed. All three digital systems had narrower but higher peaks compared with the films. The integrals for the digital systems were considerably larger than those for the two film types.

CONCLUSIONS

All the three digital systems have superior psychophysical properties compared with the two tested films.

Perceptibility curve test for digital radiographs before and after correction for attenuation and correction for attenuation and visual response

OBJECTIVE

Two digital image processing methods, correction for X-ray attenuation and correction for attenuation and visual response, have been developed. The aim of the present study was to compare digital radiographs before and after correction for attenuation and correction for attenuation and visual response by means of a perceptibility curve test.

MATERIAL AND METHODS

Radiographs were exposed of an aluminium test object containing holes ranging from 0.03 mm to 0.30 mm with increments of 0.03 mm. Fourteen radiographs were exposed with the Dixi system (Planmeca Oy, Helsinki, Finland) and twelve radiographs were exposed with the F1 iOX system (Fimet Oy, Monninkylä, Finland) from low to high exposures covering the full exposure ranges of the systems. Radiographs obtained from the Dixi and F1 iOX systems were 12 bit and 8 bit images, respectively. Original radiographs were then processed for correction for attenuation and correction for attenuation and visual response. Thus, two series of radiographs were created. Ten viewers evaluated all the radiographs in the same random order under the same viewing conditions. The object detail having the lowest perceptible contrast was recorded for each observer. Perceptibility curves were plotted according to the mean of observer data.

RESULTS

The perceptibility curves for processed radiographs obtained with the F1 iOX system are higher than those for originals in the exposure range up to the peak, where the curves are basically the same. For radiographs exposed with the Dixi system, perceptibility curves for processed radiographs are higher than those for originals for all exposures. Perceptibility curves show that for 8 bit radiographs obtained from the F1 iOX system, the contrast threshold was increased in processed radiographs up to the peak, while for 12 bit radiographs obtained with the Dixi system, the contrast threshold was increased in processed radiographs for all exposures. When comparisons were made between radiographs corrected for attenuation and corrected for attenuation and visual response, basically no differences were found.

CONCLUSION

Radiographs processed for correction for attenuation and correction for attenuation and visual response may improve perception, especially for 12 bit originals.

Perceptibility curves for the Digora system

OBJECTIVES

To construct perceptibility curves (PCs) for given calibration settings in order to define psychophysical properties of the Digora storage phosphor system and to evaluate the effects of automatic exposure correction (AEC) on the PCs.

METHODS

The Digora system was calibrated at two exposures, 80 microC kg(-1) (high calibration) and 40 microC kg(-1) (low calibration). Since the grey levels displayed in the radiographs are adjusted by AEC, dose-response functions at high calibration were obtained using AEC on and off modes. The dose-response function at low calibration was obtained with AEC off. The PC at each experimental setting was calculated using known physical parameters of the system and the performance of the average observer used in a previous study. In addition, PCs were also constructed using transmitted radiation flux behind the test object calculated from the attenuation coefficient in order to study observer and system performance. PCs obtained under these conditions were compared.

RESULTS

The PC using calculated transmitted radiation flux behind the test object showed a wide plateau at the peak owing to AEC, while the PC obtained by a modified approach showed a higher but narrower peak. There were no differences between the two PCs using AEC on and off modes when the PCs were constructed using a modified approach. There were no differences between the two PCs obtained at high and low calibration settings or between the three PCs obtained with AEC on except for the position along the exposure axis.

CONCLUSIONS

Psychophysical properties of the Digora system may be determined if we employ registered exposures from a dose-response function with AEC off under a given calibration setting. Under these circumstances the shape and height of the PCs will be unchanged irrespective of the AEC mode.

Detection of approximal caries in digital radiographs before and after correction for attenuation and visual response. An in vitro study

OBJECTIVE

To evaluate if digital compensation for exponential attenuation and the characteristics of the human visual system improves the diagnosis of approximal caries from digital radiographs.

MATERIAL AND METHODS

Forty premolar teeth were mounted in plaster blocks. Radiographs of the teeth were exposed with the Dixi digital intraoral system employing a Prostyle Intra dental X-ray unit (Planmeca Oy, Helsinki, Finland). Thirteen radiographs were then processed to compensate for the exponential attenuation and for the characteristic of the human visual system using equations presented in the paper. Ten observers were asked to diagnose approximal caries in all radiographs. ROC analyses were performed. The teeth were subsequently sectioned for histological validation of the lesions. The areas under ROC curves of original and processed radiographs were compared and analysed using Wilcoxon's signed-ranks test.

RESULTS

There were significant diagnostic differences between the two types of radiographs (all lesions P=0.005. enamel P=0.028, and dentine P=0.050).

CONCLUSION

Digital radiographs processed to compensate for exponential attenuation and the characteristics of the human visual system significantly improves the diagnosis of approximal caries in vitro.

The effect of hyaluronan on bone and soft tissue and immune response in wound healing

BACKGROUND

The aims of this study were to investigate the anti-inflammatory effect and the effect on bone regeneration of hyaluronan in surgical and non-surgical groups.

METHODS

In each of 15 individuals, 2 teeth with defects of similar character and magnitude in the upper or lower jaw were chosen. There were at least 2 teeth between the test and the control sites. In the surgical group, a bioabsorbable membrane was used for both test and control sites, and hyaluronan was placed in the intrabony pocket of the test site. In the non-surgical group, the periodontal pockets were scaled and hyaluronan was administered 3 times with an interval of 1 week in the test pockets. Alveolar bone height and bone healing patterns were analyzed using digital intraoral radiographs. Measurements of bone height were performed in the original digital black-and-white radiographs to obtain quantitative data on bone gain or loss. Bone healing patterns were studied with color-coded radiographs, using specially designed software in a personal computer with subsequent combinations of radiographs. Gingival crevicular fluid immunoglobulin (Ig)G, C3, and prostaglandin E2 (PGE2) responses; periodontal probing depth; bleeding on probing; and the presence of plaque were studied to evaluate the anti-inflammatory effect. Data were obtained at baseline before treatment, and at 2 weeks, and 1, 3, 6, and 12 months after treatment.

RESULTS

For the surgical treatments, bone height was increased in the test group treated with hyaluronan (mean value 2.2%, corresponding to an average increase of approximately 0.5 mm) and reduced in the control group (mean value -1.8%, corresponding to an average decrease of approximately - 0.4 mm) (P<0.05) after 12 months. For the non-surgical treatments, bone height was reduced by a mean value of -1.1% (corresponding to an average decrease of approximately -0.25 mm) in the test group treated with hyaluronan and -3.3% (corresponding to an average decrease of approximately -0.75 mm) in the control group after 12 months (N.S.). According to the digital color-coded radiographs, the test sites in the surgical and non-surgical groups showed apposition of bone minerals. Immune responses showed no differences during the 12 months studied for the surgical and non-surgical sites. Mean periodontal probing depths were reduced between 2.5 mm and 4.1 mm in the surgical and non-surgical groups.

CONCLUSIONS

The observed difference in bone height between test and control sites in the surgical group after 12 months was less than 1 mm, which was only detectable on radiographs. No statistical difference was found on radiographs in the non-surgical group, where a decrease in bone height was found for both groups after scaling. Probing depth reduction after the surgical treatment, as well as after scaling and root planing, was as expected. Hyaluronan in contact with bone and soft tissues had no influence on the immune system in this study. Further studies are needed to determine the extent to which hyaluronan can lead to clinically significant healing of periodontal lesions.

Conventional and predicted perceptibility curves for contrast-enhanced direct digital intraoral radiographs

OBJECTIVES

To construct Perceptibility Curves (PCs) for contrast-enhanced digital intraoral radiographs.

METHODS

Radiographs of a test object having holes of increasing depths were exposed using three digital systems, the CDR (Schick Technologies, Long Island, NY, USA), the Dixel (J Morita MFG, Kyoto, Japan) and the Sens-A-Ray (Regam Medical Systems, Sundsvall, Sweden). The radiographs were contrast-enhanced and PCs constructed in the conventional way using 10 observers. Predicted PCs were calculated and compared with observer data.

RESULTS

The PCs showed that contrast enhancement is effective for the perception of small contrast details, especially in the low exposure range. Predicted PCs demonstrated excellent agreement with observer data.

CONCLUSIONS

Contrast enhancement should be advantageous in digital radiography. The effects of contrast enhancement on PCs may be predicted without previous knowledge of observer performance.

Eruption pattern of autotransplanted premolars visualized by radiographic color-coding

Eruption patterns and root growth were visualized with the use of a new technique, radiographic color-coding, for comparison of the development of autotransplanted premolars with contralateral control teeth. Rates of eruption and root growth were studied. The eruption pattern and rate was assessed relative to the first molar. Maximum rates were found to occur between 30 and 60 days after transplantation. There were no significant differences between transplants and their contralaterals. Two distinct categories of eruption patterns were demonstrated. One group showed a tendency toward an initial rate of transplant eruption that was somewhat faster than that of the contralaterals. The other group showed initially retarded eruption. Possible explanations were discussed. Because no significant differences between the transplants and the contralaterals were observed, it was concluded that autotransplantation is a sound treatment option for substitution of missing teeth, at least from a tooth development point of view.

Validation of DIAGNOdent for quantification of smooth-surface caries: an in vitro study

The aims were 1) to validate a laser-based device, KaVo DIAGNOdent, for quantification of caries lesions on smooth surfaces, using histopathologic and microradiographic analyses as the gold standard, and 2) to test inter- and intra-observer agreements. We also investigated the influence on DIAGNOdent readings of the storage medium used for extracted teeth. Two observers measured independently the tooth surfaces of 40 extracted premolars that had been stored in thymol-saturated saline. After subsequent storage in neutral-buffered formalin for 14 days they were re-measured. The teeth were then sectioned for histopathologic and microradiographic analysis. The Spearman rank correlation coefficients between lesion depth and DIAGNOdent readings were 0.78-0.83 and 0.85 for teeth stored in thymol-saturated saline and formalin, respectively. Inter- and intra-observer agreements were 0.94 and 0.95 when the teeth were stored in thymol-saturated saline. The DIAGNOdent reading was almost 1.5 times higher for teeth stored in formalin than for those stored in thymol saline. The Spearman rank correlation coefficient between mineral loss in enamel (deltaZ) and DIAGNOdent readings ranged from 0.64 to 0.68. It was concluded that DIAGNOdent may be helpful for assessing smooth-surface caries, but the cut-off points need to be assessed under clinical conditions. The increase in fluorescence associated with storage of teeth in formalin warrants further investigation.

Comparison of QLF and DIAGNOdent for quantification of smooth surface caries

The aim was to compare the detection and quantification of smooth surface caries by KaVo DIAGNOdent and quantitative laser/light-induced fluorescence (QLF) using a laser and a lamp as two different light sources. On 40 premolar teeth extracted from adolescents, 71 non-cavitated approximal surfaces were assessed. For QLF, both mean and maximum fluorescence losses were registered. To provide a gold standard for verification, the teeth were then sectioned and lesion depth, stratified on a five-point scale, was determined by histopathology and microradiography. The correlation between the gold standard and the two methods was assessed by Spearman's rank correlation coefficient. The sensitivity and specificity of the methods for detection of smooth surface caries at D(3) level were also assessed. For lesion depth, correlation with the gold standard was similar for QLF and DIAGNOdent: about 0.85. With respect to dentinal caries detection, sensitivity for DIAGNOdent was 0.75 and specificity 0.96, with a cut-off point of 9. The corresponding values for QLF were 0.94 and 1, with a cut-off value of 20% of fluorescence loss. Spearman's rank correlation coefficients for enamel mineral loss and QLF and DIAGNOdent, respectively, were 0.76 and 0.67. It was concluded that for quantification of smooth surface caries, the methods are of equal merit, but for scientific purposes, QLF offers the advantage of closer correlation with changes in mineral content.

Tuned-aperture computed tomography for detection of occlusal caries

OBJECTIVES

To evaluate the use of tuned-aperture computed tomography (TACT) for the detection of primary occlusal caries.

MATERIALS AND METHODS

The material comprised 76 extracted posterior teeth, 51 with caries. Radiographs were recorded both with the Sens-A-Ray (Regam Medical Systems Int. AB, Sundsvall, Sweden) digital radiographic system and with Kodak EktaSpeed Plus film (Eastman-Kodak Co., Rochester NY, USA) employing an Orthopantomograph OP 100 (Instrumentarium Imaging, Tuusula, Finland) and a Prostyle Intra (Planmeca, Helsinki, Finland) dental unit respectively. The Sens-A-Ray radiographs were used to construct TACT slices and TACT iterative slices. The teeth were subsequently sectioned in 300 microm thick slices. Microradiographs were exposed and analysed with respect to the true presence of lesions. Seven observers subjectively evaluated the radiographs and ROC analyses performed. Conventional radiographs were compared with TACT images by means of the area under the ROC curves, Az. Paired t-test was used to compare Az values. Interobserver agreement was evaluated using the Kendall coefficient and the Friedman Anova.

RESULTS

TACT radiographs were significantly better than conventional radiographs for diagnosing all types of occlusal caries combined (P(TACT) (slices)=0.02. P(TACT) (iterative slices)=0.01). However, neither TACT system was significantly better than film for enamel and dentinal caries separately. Observer agreement was moderate. However, observers demonstrated significant systematic differences in their readings (P<0.001).

CONCLUSION

TACT may be a feasible method for diagnosing primary occlusal caries.

Prevalence of antibodies to Toxoplasma gondii in the sera of rare wildlife in the Shanghai Zoological Garden, People's Republic of China

The prevalence of antibodies to Toxoplasma gondii in the sera of rare wildlife in the Shanghai Zoological Garden, PR China, was examined using a modified agglutination test (MAT) and an enzyme-linked immunosorbent assay (ELISA). Forty-one (35%) of 117 animals belonging to two classes, 10 orders, 18 families, 37 genera and 52 species (including sub-species) were sero-positive for MAT. By MAT, T. gondii antibodies were found in 11.1% (4/36) of birds, in 25% (4/16) of primates, in 69.4% (25/36) of carnivores and in 27.6% (8/29) of herbivores. Thirty-three (33.7%) of 98 animals tested by protein A ELISA were sero-positive. By ELISA, T. gondii antibodies were found in none of 36 birds, in 33.3% (4/12) of primates, in 87.1% (27/31) of carnivores and in 10.5% (2/19) of herbivores.

Occlusal caries detection with KaVo DIAGNOdent and radiography: an in vitro comparison

A new laser fluorescence method, KaVo DIAGNOdent, was tested with respect to reproducibility and validity and compared with radiography regarding accuracy in the detection of occlusal caries. Seventy-six extracted premolar and molar teeth were measured twice with DIAGNOdent under both wet and dry conditions, at an interval of 2 weeks. Conventional film radiographs were exposed. Microradiographic analysis of sections of the teeth served as the gold standard. Intra-class correlation coefficient and Pearson's correlation coefficient were used to assess the reproducibility and the validity of the method, respectively. The influence of time and varying humidities on DIAGNOdent readings were analysed by two-way repeated measure ANOVA. ROC curves were plotted for DIAGNOdent readings and radiographic registration of caries by 6 observers, and the areas under the curves were compared using Student's t test. Under both wet and dry conditions, the reproducibility of the DIAGNOdent method was excellent: R = 0.97 and 0.96, respectively. The diagnostic accuracy of DIAGNOdent was significantly better than that of radiography (p< or =0.001). In this in vitro study of detection of occlusal caries, the diagnostic performance of the DIAGNOdent method was superior to that of radiography.

Physical evaluation of a system for direct digital intra-oral radiography based on a charge-coupled device

OBJECTIVES

To determine technical properties of a direct digital intra-oral radiographic system, the Dixel(R) (J Morita Corporation, Kyoto, Japan).

METHODS

A dose response function and the dark current were calculated from two series of exposures to a homogeneous radiation field. The line spread function (LSF) and the modulation transfer function (MTF) were determined from radiographs of an edge. The noise power spectrum (NPS) was determined at three exposures from radiographs exposed to homogeneous radiation fields. Noise equivalent quanta (NEQ) were calculated from the one-dimensional NPS and the MTF. The detective quantum efficiency (DQE) was determined from the NEQ and a representative value of the photon fluence. Signal-to-noise ratios (SNR) were calculated from the NEQs and different signal contrasts.

RESULTS

The dose response function demonstrated a slight curvature. There was no effect of the dark current. NPS ranged from 10-5 - 10-7 mm2 depending on exposure and frequency. At a peak of about 2 cycles/mm the DQE is on an average about 30 per cent. SNRs are favorable.

CONCLUSION

The technical properties found in this study indicate that the Dixel(R) system is suitable for intra-oral dental radiography.

Prediction of perceptibility curves of direct digital intraoral radiographic systems

OBJECTIVES

To derive and test a method to predict Perceptibility Curves (PCs) for direct digital intraoral radiographic systems.

METHODS

A test object was used to determine the performance of an average observer with respect to the threshold contrast and internal noise of the human visual system. These data were combined with system parameters to predict PCs mathematically.

RESULTS

Data on the performance of an average observer could be defined to obtain values of the effective threshold contrast as a function of background gray level. This function combined with the gamma-value of the system predicted PCs that agreed well with PCs obtained in the conventional way.

CONCLUSION

It is possible to predict PCs from a limited number of system parameters together with predetermined data on an average observer.

Orthodontic application of color image addition to visualize differences between sequential radiographs

A new technique was developed making it possible to visualize changes that take place after premolar transplantation. Three sequential radiographs from a series of standardized control examinations were digitized and registered to the first radiograph in the series using subtraction technique. The digitized radiographs were then transformed into monochromatic images: red, blue, and green. After correction of gray level and contrast, the three radiographs were superimposed. All details that were common in the radiographs were then displayed in black-and-white. Details that were different appeared in color. Red and blue combines into magenta, blue and green into cyan, and green and red into yellow. A procedure was developed to create color-coded radiographs according to the above. The procedure was applied to cases that had been treated by premolar transplantation. The color coding offers the possibility to identify any radiographic changes that take place over time, eg, growth, apposition or resorption of bone, and progression or regression of pathological processes.

A simplified method to obtain perceptibility curves for direct dental digital radiography

OBJECTIVES

To derive and test a simplified method to construct Perceptibility Curves (PCs) for dental digital detectors.

METHODS

Mathematical expressions were derived to make it possible to construct PCs from viewer data obtained at two exposures, one low and one high. PCs were constructed applying these expressions and compared with data previously obtained employing the conventional method.

RESULTS

PCs constructed according to the simplified method agree extremely well with conventionally obtained data.

CONCLUSIONS

Reliable PCs may be constructed according to the simplified method.

Comparison of observer reliability in assessing alveolar bone changes from color-coded with subtraction radiographs

OBJECTIVES

To assess intra- and interobserver agreement on marginal changes in periodontal bone from color-coded compared with subtraction radiographs.

METHODS

Sequential radiographs from patients undergoing periodontal treatment were acquired using direct digital intra-oral radiography. Fifty-one pairs of color-coded and subtraction radiographs were produced and evaluated twice by six dentists for changes in marginal bone. Intra- and interobserver agreement were calculated.

RESULTS

Intra-observer agreement was significantly higher for the color-coded radiographs (P < 0.05). Interobserver agreement was significantly higher for color-coded radiographs at the second (P < 0.001) but not the first (P = 0.34) evaluation.

CONCLUSIONS

Color coding of radiographic differences by means of image addition may be a feasible alternative to the subtraction technique for evaluating periodontal bone changes.

The perceptibility curve test applied to direct digital dental radiography

OBJECTIVE

To compare the effect of an additional scintillator layer on the psychophysical properties of a CCD detector for digital dental radiography.

METHODS

Radiographs of a test object containing ten holes of increasing depth were obtained throughout the exposure range of two CCD detectors at 70 and 90 kVp. One was the original detector for the Sens-A-Ray system (Regam Medical Systems, Sundsvall, Sweden) and the other the same detector covered by a scintillator layer. Ten viewers evaluated the radiographs for the number of perceptible holes. From these data and the dose response functions for the two detectors, the minimum perceptible exposure difference was found. The reciprocal values of this parameter were plotted against the logarithm of exposure to create Perceptibility Curves (PCs).

RESULTS

The four PCs had essentially the same shape and height. There was a shift to lower exposures in the PCs for the detector covered by a scintillator.

CONCLUSIONS

The two detectors have essentially the same psychophysical properties. Since the detector covered by a scintillator layer is more sensitive, it should be preferred for clinical practice since the dose to the patient is reduced.

A sensitometric comparison of four dental X-ray films and their diagnostic accuracy

OBJECTIVES

To compare the sensitometric properties and accuracy in the diagnosis of approximal caries of two E-speed (Ektaspeed Plus and EV 57) and two D-speed (Ultra-speed and DV 57) films.

METHODS

Speed and contrast for the four films were determined following 30 exposures for each film. Base plus fog density was measured on unexposed films and the increase was studied over a 18-month period. Seventy-five extracted premolars with known pathology were radiographed under standardized conditions and the radiographs assessed by nine observers for approximal caries. Receiver Operating Characteristic (ROC) curve technique was used to analyse the diagnostic accuracy.

RESULTS

The sensitometric analysis showed that the Ektaspeed Plus film had the highest speed of the four films. At a density of 1.0 it was 2.28 times faster than Ultra-speed. The contrast of Ektaspeed Plus was comparable with that of the other films and base plus fog density plateaued at 0.4 ten months before expiry date. There were no statistically significant differences in diagnostic accuracy for white spot lesions between the four films. For cavitations there was a significant difference between EV 57 and DV 57 and Ektaspeed Plus (P = 0.005) but not between Ultra-speed and Ektaspeed Plus nor between Ultra-speed and EV 57 and DV 57.

CONCLUSION

Ektaspeed Plus film is comparable with D-speed and a conventional E-speed film. Since it is at present the fastest available dental film it should be recommended for general dental practice.

Expression of the BE-20 epididymal protein gene: in situ hybridization

A protein designated as BE-20 was purified from cauda epididymal fluid of male rabbits and the amino acid sequence of the N-terminus was determined. A 23-mer oligonucleotide coding the N-terminal eight amino acids of the BE-20 protein was synthesized. The oligonucleotide was used as sense primer with rabbit epididymal mRNA as template in the RT-PCR system. The BE-20 cDNA consisted of 499 bp with an open reading frame of 285 bp encoding a deduced polypeptide composed of 95 amino acids. Digoxigenin-labeled BE-20 cDNA was prepared and used as a hybridization probe to detect the specific mRNA. The probe interacted with a 1.2-kb mRNA prepared from rabbit epididymis; mRNAs prepared from rabbit testis gave negative reaction. Using tissue sections, the BE-20 mRNA was located in the epithelial cells of the cauda epididymis and proximal segment of the ductus deferens by in situ hybridization method. Sections of the corpus and caput epididymis, testis, and liver gave negative reaction. Polyclonal anti-BE-20 antibodies were raised and found to inhibit in vitro the capacity of human sperm to penetrate zona-free hamster ova. The results suggest that BE-20 protein may influence maturation of spermatozoa during its movement through the epididymis and/or the capacity of sperm to fertilize ova.

Identification of a rabbit epididymal protein gene

A protein designated as BE-20 was purified from cauda epididymal fluid of the rabbit by preparative polyacrylamide gel electrophoresis and HPLC on a mono Q HR5/5 anion exchange column. The purified protein migrated with an estimated Mt of 20,000 when analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The amino acid sequence of the N-terminus of the BE-20 protein was determined. The initial eight amino acid residues were His-Gly-Ala-Asp-Lys-Pro-Gly-Val. The corresponding 23 mer oligonucleotide (5'-CATGGCGCTGACAAGCCTGGGGT-3') was synthesized and used as sense primer with rabbit epididymal mRNA as template in the RT-PCR system. The purified BE-20 cDNA consisted of 499 bp with an open reading frame of 285 bp encoding a deduced polypeptide composed of 95 amino acids. The BE-20 cDNA had 78.5% identity in 479 bp overlap with human epididymis-specific HE4 cDNA. The amino acid sequences of the initial 30 amino acid residues of the N-terminus of the purified protein and the deduced polypeptides were as follows: N-His-Gly-Ala-Asp-Lys-Pro-Gly-Val-Cys-Pro-Gln-Leu-Ser-Ala-Asp-Leu-Asn-Cy s- Thr-Gln-Asp-Cys-Arg-Ala-Asp-Gln-Asp-Cys-Ala-Glu. The deduced polypeptide contained 16 cysteine residues and had partial sequence homology with proteins belonging to the four-disulfide core family of extracellular proteinase inhibitors. The BE-20 protein may play a role in sperm maturation and/or capacitation.

Effect of extract of Hirudo Medicinalis L. against adherence of calcium oxalate crystals to acid-injured bladder mucosa

The effect of extract of Hirudo Medicinalis L. on preventing the adhesion of calcium oxalate crystals to 0.1 M hydrochloric acid-injured bladder urothelium of the rat was studied. It was found that in this species the extract coated to the bladder mucosa after it was instilled into the chemically injured bladder; and the adhesion of calcium oxalate crystals was prevented. In regard to the anti-adhesion property the Hirudo extract appears more effective than heparin, a documented glycosaminoglycan.

Antifertility effect of polyvinylpyrrolidone-gossypol and gossypol in male rats

Thirty-nine adult male Wistar rats were administered 20 mg/kg or 24.3 mg/kg polyvinylpyrrolidone-gossypol (PVP-G) and 20 mg/kg gossypol acetic acid (G-A) 6 times a week for 6 weeks. Mating test was taken to evaluate the antifertility effect. Caudal sperm count, body weight, sex and accessory sex organ weights were recorded. At the end of 6 weeks treatment, the recovery period of 6 weeks was investigated. The results showed that the onset of antifertility action and recovery with PVP-G are faster than with G-A.