Abstract Introduction Several recent studies have evaluated the presence of dentinal defects after root canal preparation in extracted human teeth by using the root sectioning methodology. The ...objective of this research was to investigate whether light-emitting diode (LED) transillumination enhances the visualization of dentinal defects by using a root sectioning methodology. Methods Forty mesial roots of mandibular molars were sectioned at 3, 6, and 9 mm from the apex with a low-speed saw under water cooling. Microscopic pictures of the specimens were taken by using ×19.2 magnification for the 3-mm slice and ×12.8 magnification for the 6- and 9-mm slices. The LED transillumination was done by positioning an LED probe at 4 different locations (mesial, distal, buccal, and lingual). The root canal lumen was masked, and 2 independent evaluators assessed the presence of dentinal defects on the non-LED and LED images. The number of dentinal defects was recorded, and χ2 test was used for statistical analysis ( P < .05). Results The number of slices presenting dentinal defects at 3, 6, and 9 mm were 2 (5%), 1 (2.5%), and 1 (2.5%), respectively, for the non-LED assessment and 8 (20%), 10 (25%), and 9 (22.5%), respectively, for the LED assessment. Overall, 4 of the specimens (10%) presented dentinal defects without LED evaluation, and 19 of the specimens (47.5%) presented dentinal defects with LED evaluation. This difference was statistically significant ( P < .05). Conclusions LED transillumination enhanced the visualization of dentinal defects in uninstrumented roots. The results from previous studies that used the traditional non-LED sectioning methodology should be evaluated with caution.
A multi-grid method is one of the most powerful linear solvers for finite element electromagnetic field analysis. However, as the discretized model has recently been enlarged, a solution process for ...a linear system arising on the coarsest level tends to be problematic in a complete multi-grid solution process. Whereas a linear system on the coarsest level is generally solved by a direct solver, we solve it here by means of an iterative solver to reduce the memory requirements. Since a conventional preconditioning technique is not effective for such a linear system, we introduce preconditioning techniques based on Arnold, Falk, and Winther’s and on Hiptmair’s smoothers. Numerical tests show that the newly installed preconditioning technique greatly improves the convergence rate.
Background
Bisphosphonate and denosumab are widely used for the treatment of osteoporosis and bone metastasis of cancer to prevent excessive bone resorption. Osteonecrosis of the jaw is a serious ...adverse effect of bisphosphonate or denosumab referred to as bisphosphonate-related osteonecrosis of the jaw (BRONJ) or denosumab-related osteonecrosis of the jaw (DRONJ), respectively. Since bisphosphonate and denosumab inhibit bone resorption by different mechanism, we evaluated whether these drug types result in different histopathological characteristics related to bone resorption.
Materials and Methods
We histopathologically investigated 10 cases of BRONJ, DRONJ, and suppurative osteomyelitis. Paraffin sections prepared from decalcified dissected jaw bones were used for histopathological observation, second harmonic generation imaging, and bone histomorphometry. The samples were also observed by a scanning electron microscope.
Results
Numerous bone resorption lacunae were observed on the necrotic bone surface in almost all cases of BRONJ; however, such resorption lacunae were limited in DRONJ and suppurative osteomyelitis. Prominent bone resorption lacunae were also confirmed by second harmonic generation imaging and scanning electron microscopy in BRONJ, but not in DRONJ or suppurative osteomyelitis. As determined by bone histomorphometry, the number of bone resorption lacunae and the length of the erosion surface of resorption lacunae were significantly higher in BRONJ group than in the DRONJ and suppurative osteomyelitis groups. These parameters were correlated between the necrotic bones and the vital bones in BRONJ.
Conclusions
Persistent bone resorption lacunae on the necrotic bone surface are unique to BRONJ, providing a basis for distinguishing BRONJ from DRONJ and OM in histopathological diagnosis.
Transgenic Mice Susceptible to Poliovirus Koike, Satoshi; Taya, Choji; Kurata, Takeshi ...
Proceedings of the National Academy of Sciences - PNAS,
02/1991, Volume:
88, Issue:
3
Journal Article
Peer reviewed
Open access
Poliovirus-sensitive transgenic mice were produced by introducing the human gene encoding cellular receptors for poliovirus into the mouse genome. Expression of the receptor mRNAs in tissues of the ...transgenic mice was analyzed by using RNA blot hybridization and the polymerase chain reaction. The human gene is expressed in many tissues of the transgenic mice just as in tissues of humans. The transgenic mice are susceptible to all three poliovirus serotypes, and the mice inoculated with poliovirus show clinical symptoms similar to those observed in humans and monkeys. Rabbit anti-poliovirus serum detects the antigens mainly in motor neurons in the anterior horn of the spinal cord and in nerve cells in the medulla oblongata and pons of the paralyzed transgenic mice. Therefore, cell types sensitive to poliovirus in the central nervous system of the transgenic mice appear to be identical to those of humans and monkeys. Furthermore, many more doses of oral poliovirus vaccine strains than of the virulent strains are required to cause paralysis in the transgenic mice. This may reflect the observation that the virulent strain multiplies more efficiently in the central nervous system than the attenuated strain. Thus, the transgenic mice may become an excellent new animal model to study molecular mechanisms of pathogenesis of poliovirus and to assess oral poliovirus vaccines.
Exposure to mushroom spores may cause many respiratory allergic diseases, however, there has been no serial study in a mushroom factory to address this problem. The aim of this study was to ...investigate the serial changes in respiratory allergy and the incidence of hypersensitivity pneumonitis (HP) in mushroom workers. A 3-year follow-up study, beginning in June 1996, was conducted in a newly operating mushroom factory in which one kind of mushroom is produced: Hypsizigus marmoreus (Bunashimeji). Allergic symptoms, chest roentgenogram, serum precipitins to the spores and soluble adhesion molecules in sera were evaluated once a year in 60 workers and 20 controls. Three out of the 60 subjects were diagnosed as having HP caused by inhalation of the mushroom spore and they were therefore excluded from this study, and the 57 non-HP subjects were evaluated. In this study 24 workers quit because of intolerable cough, runny nose, wheezing, sputum, fever elevation and/or shortness of breath at their place of work. During each year of this study as many as 70–80% of employees suffered some of the above symptoms, cough being the most frequent, and positive rate of serum precipitins to the spore revealed 30% in 1996, 93% in 1997 and 94% in 1998. From the June 1996 examination until the following May, serum soluble intercellular adhesion molecule-1 levels of the 15 workers who quit during that period were significantly higher than those in the 42 workers still employed in 1997 (P<0·05). Workers in Bunashimeji mushroom factories might be at critical risk of developing respiratory allergy. In our 3-year study, over 90% workers were sensitized to the spore, 40% quit because of the symptoms and 5% developed HP. It was suggested that workers should be counselled about the risk of mushroom allergy and precautionary measures should be taken to prevent its occurrence.
In this paper, a power factor correction (PFC) based on active-clamped full-wave quasi-resonant (ZCS-QR) boost converter is presented. This circuit is characterized by zero-voltage-switched (ZVS) and ...zero-current-switched (ZCS) that results in higher efficiency, opens possibility to incorporate higher switching frequency, and has some potency to reduce converter's conducted EMI. The working principle and steady state performance of the proposed converter are presented. A 100 V dc input, 180 W maximum output, and 440 kHz resonant frequency experimental circuit has been built. Maximum efficiency of 93% and the proof of compliance to the IEC61000-3-2 class D have been confirmed by experiment.
During the process of growth and development, the digastric muscle is subjected to marked functional changes, including the change from suckling to mastication. In particular, because the anterior ...belly of the digastric muscle, which is one of the suprahyoid muscles, plays an important role in mastication. Therefore, this muscle seems to undergo a marked functional change before and after weaning. However, the details remain unknown. Here, to clarify the changes in the muscle fibre characteristics of the anterior belly of the digastric muscle before and after weaning, we examined myosin heavy chain isoforms at the protein (immunohistochemistry) and mRNA (transcription) levels. As a control, the changes in the muscle fibre characteristics of the sternohyoid muscle, which is anatomically aligned in the same direction as the anterior belly of the digastric muscle, were analyzed. The results showed that, in the anterior belly of the digastric muscle that is involved in mandibular movements in mice, the ratio of a fast-contraction isoform with strong contractile force increased after weaning. We believe that this occurred in response to a functional change from suckling to mastication. On the other hand, there was little change in the composition of sternohyoid muscle.
Development of an effective therapy to overcome colistin resistance in Klebsiella pneumoniae, a common pathogen causing catheter-related biofilm infections in vascular catheters, has become a serious ...therapeutic challenge that must be addressed urgently. Although colistin and EDTA have successful roles for eradicating biofilms, no in vitro and in vivo studies have investigated their efficacy in catheter-related biofilm infections of colistin-resistant K. pneumoniae. In this study, colistin resistance was significantly reversed in both planktonic and mature biofilms of colistin-resistant K. pneumoniae by a combination of colistin (0.25-1 µg/ml) with EDTA (12 mg/ml). This novel colistin-EDTA combination was also demonstrated to have potent efficacy in eradicating colistin-resistant K. pneumoniae catheter-related biofilm infections, and eliminating the risk of recurrence in vivo. Furthermore, this study revealed significant therapeutic efficacy of colistin-EDTA combination in reducing bacterial load in internal organs, lowering serum creatinine, and protecting treated mice from mortality. Altered in vivo expression of different virulence genes indicate bacterial adaptive responses to survive in hostile environments under different treatments. According to these data discovered in this study, a novel colistin-EDTA combination provides favorable efficacy and safety for successful eradication of colistin-resistant K. pneumonia catheter-related biofilm infections.
PDF
