Oral administration of inorganic nitrate alleviated biological damage induced by cone-beam computed tomography examination in Wistar rats.

OBJECTIVES: To explore whether the inorganic nitrate has a protective effect on biological damage induced by cone-beam computed tomography (CBCT) and compare it with Vitamin C. MATERIALS AND METHODS: Sixty Wistar rats were randomly separated into 6 groups: control group, irradiation (IR) group, NaNO3 group, IR + NaNO3 group, Vitamin C group, and IR + Vitamin C group. Rats were whole-body irradiated with CBCT four times. The absorbed dose of the skin surface was measured using thermoluminescent dosemeter chips and the mean whole-body absorbed dose was calculated. Peripheral blood was collected at 0.5 h and 24 h after irradiation. Bodyweight and organ index of rats before and after irradiation were analyzed. The bone marrow was taken for micronucleus test. Lymphocytes were isolated from peripheral blood for γ-H2AX immunofluorescence assay, apoptosis and reactive oxygen species (ROS) analysis. Total antioxidant capacity (TAC), malondialdehyde (MDA) and superoxide dismutase (SOD) in serum were detected. RESULTS: The mean absorbed dose of four whole-body CBCT scans for rats was 73.04 mGy. Bodyweight and organ index before and after irradiation with X-ray had no significant differences. The micronuclei frequency of IR + NaNO3 and IR + Vitamin C groups showed a significant decrease than that in the IR group, which was not significantly different from that of the control group. The γ-H2AX foci rates in the IR + NaNO3 group and the IR + Vitamin C group were significantly lower than that in the IR group. In addition, the foci rate of the IR + NaNO3 group returned to the baseline level of the control group 24 h after CBCT scanning. The apoptosis of lymphocytes in rats did not increase. The IR + NaNO3 group (P < 0.001) or IR + Vitamin C group (P < 0.001) showed a significant increase in ROS positive cells rate with the control group, while were significantly lower than those in the IR group (P < 0.01). In addition, the ROS-positive cell rate in the IR + NaNO3 group was significantly lower than that in the IR + Vitamin C group. The MDA in the serum of rats increased significantly, while SOD and TAC decreased significantly at 0.5 h after irradiation. CONCLUSIONS: Compared with Vitamin C, inorganic nitrate had better preventive effects on biological damage induced by CBCT scans in rats.

Dietary nitrate supplementation prevents radiotherapy-induced xerostomia.

Management of salivary gland hypofunction caused by irradiation (IR) therapy for head and neck cancer remains lack of effective treatments. Salivary glands, especially the parotid gland, actively uptake dietary nitrate and secrete it into saliva. Here, we investigated the effect of dietary nitrate on the prevention and treatment of IR-induced parotid gland hypofunction in miniature pigs, and elucidated the underlying mechanism in human parotid gland cells. We found that nitrate administration prevented IR-induced parotid gland damage in a dose-dependent manner, by maintaining the function of irradiated parotid gland tissue. Nitrate could increase sialin expression, a nitrate transporter expressed in the parotid gland, making the nitrate-sialin feedback loop that facilitates nitrate influx into cells for maintaining cell proliferation and inhibiting apoptosis. Furthermore, nitrate enhanced cell proliferation via the epidermal growth factor receptor (EGFR)-protein kinase B (AKT)-mitogen-activated protein kinase (MAPK) signaling pathway in irradiated parotid gland tissue. Collectively, nitrate effectively prevented IR-induced xerostomia via the EGFR-AKT-MAPK signaling pathway. Dietary nitrate supplementation may provide a novel, safe, and effective way to resolve IR-induced xerostomia.

Head and neck cancers are commonly treated using radiotherapy, where a beam of high-energy radiation is targeted at the tumour. This often severely damages the surrounding salivary glands, leading to chronic dry mouth and impairing a patient's sense of taste, nutrient intake, speech and immune system. Despite this significant impact on quality of life, there is no effective treatment yet for this side effect. In the body, salivary glands are one of the primary users of a compound known as nitrate, which is commonly found in the diet. In the glands, it is ushered into cells thanks to a protein known as sialin. The nutrient supports the activity and maintenance of the glands, before it is released in the saliva. Feng, Wu et al. therefore decided to test whether nitrate could offer protection during neck and head radiotherapy. The experiments used miniature pigs, which have similar salivary glands to humans. The animals that received sodium nitrate before and after exposure to radiation preserved up to 85% of their saliva production. By comparison, without any additional nitrate, saliva production fell to 20% of pre-radiation levels. To understand how this protective effect emerged, Feng, Wu et al. added nitrate to cells from a human salivary gland known as the parotid. This led to the cells producing more sialin, creating a feedback loop which increases the amount of nitrate in the salivary glands. Further examination then showed that the compound promotes growth of cells and reduce their death. These findings therefore suggest that clinical studies may be worthwhile to test if nitrate could be used to prevent dry mouth in head and neck cancer patients who undergo radiotherapy.

BMP4 Moderates Glycolysis and Regulates Activation and Interferon-Gamma Production in CD4+ T Cells.

BMP4 is a key growth factor well known in promoting bone regeneration and has been reported to be able to regulate T cell development in the thymus. Here, we showed that BMP4 downregulates the activation of naïve CD4+ T cells and the IFN-γ production of CD4+ T cells without increasing regulatory T cells. BMP4 could also moderate glycolysis of T cells and regulate Hif1α expression. Furthermore, BMP4 showed a suppressive function on the IFN-γ production of CD4+ T cells in vivo. These findings indicating a mechanism by which BMP-4 may regulate activation and IFN-γ production in CD4+ T cells via metabolism moderation and suggests that BMP4 may be a potential therapeutic supplement in autoinflammatory diseases.

Total body irradiation-induced colon damage is prevented by nitrate-mediated suppression of oxidative stress and homeostasis of the gut microbiome.

Inorganic dietary nitrate plays vital roles in biological functions via the exogenous NO3-/NO2-/NO pathway under hypoxia and ischemia. We previously verified the antioxidative effects of inorganic nitrate in a mouse model of total body irradiation (TBI). Accordingly, in this study, we evaluated the effects of inorganic nitrate on prevention of TBI-induced colon injury and dysbiosis of the gut microbiome. Nitrate significantly rescued the abnormal biological indexes (body weight, white blood cell, red blood cell, platelet, hemoglobin level and intestinal canal lengths) induced by TBI. Then, we detected oxidative stress and DNA damage indexes (phospho-histone H2AX and p53 binding protein 1), which were both increased by irradiation (IR) and alleviated by nitrate. IR-induced apoptosis and senescence were ameliorated by inorganic nitrate. The distribution of the gut microbiome differed for mice with TBI and those receiving inorganic nitrate. The average abundance of Lactobacillus significantly increased, and that of Bacteroidales decreased at the genus level in the nitrate group compared with that in the IR alone group. At 30 days after TBI, the abundances of Bacteroides and Faecalibaculum decreased, whereas that of Lactobacillus increased in the IR + nitrate group compared with that in the IR alone group. Inorganic nitrate efficiently prevents TBI-induced colon epithelium injury and maintains the homeostasis of the gut microbiome. Thus, our results showed that inorganic nitrate might be a promising treatment for TBI induced colon injury.

Erratum: Histological characteristics following a long-term nitrate-rich diet in miniature pigs with parotid atrophy.

[This corrects the article on p. 6225 in vol. 8, PMID: 26261499.].

Evaluation of trabecular structure changes in osteoarthritis of the temporomandibular joint with cone beam computed tomography imaging.

OBJECTIVES: To explore the possibility of using 2-dimensional image assessments in combination with cone beam computed tomography (CBCT) in patients with temporomandibular joint osteoarthritis (TMJOA) to enhance the clinical significance and applicability of the CBCT findings on TMJOA changes. STUDY DESIGN: Fifty-two patients with unilateral TMJOA and 40 healthy adults who had undergone CBCT in preparation for orthodontic treatment were selected for this study. Temporomandibular joint images were acquired with CBCT. All images were classified into 4 phases (slight erosion, widespread erosion, appearance of bone maintenance, and partial loss of condylar head with a remodeled cortical surface) and 4 levels of severity (absent, slight, moderate, and extensive). Quantitative microstructural analysis, including bone value fraction (BV/TV), trabecular number (Tb.N), trabecular thickness, and trabecular separation (Tb.Sp) of each image, was performed by using a customized software. RESULTS: In patients with unilateral TMJOA, the affected side had significantly higher BV/TV and Tb.N and significantly lower Tb.Sp compared with the unaffected side. Compared with healthy individuals, the affected joints in patients with TMJOA had significantly higher BV/TV and trabecular thickness and significantly lower Tb.N and Tb.Sp. No significant difference was found among different phase groups or different severity levels. CONCLUSIONS: CBCT combined with a software investigation protocol for microstructure measurement can be used to provide reliable trabecular parameters in assessing TMJOA.

Histological characteristics following a long-term nitrate-rich diet in miniature pigs with parotid atrophy.

The aim of this study was to investigate the histological characteristics following a 2-year nitrate-rich diet in miniature pigs with parotid atrophy. Using averages collected data from three time points at 6, 12, and 24 months following the induction of parotid gland atrophy, salivary nitrate levels of the nitrate-diet parotid-atrophied group (17.3 ± 3.9 ng/µl) were close to those of the control group (19.6 ± 5.1 ng/µl). Compared to the control group, the nitrate-diet group had significantly higher nitrate levels in blood (P < 0.05) and urine (P < 0.001). Histological and electron microscopy analyses showed no abnormalities in the organs of experimental or control animals. No significant differences on apoptosis rate were found in liver and kidney tissues between the standard- and nitrate-diet groups. Therefore, dietary nitrate supplementation could restore salivary nitrate levels. High-dose nitrate loading for 2 years had no observed systemic toxicity in miniature pigs with parotid atrophy.

Thyroid shields for radiation dose reduction during cone beam computed tomography scanning for different oral and maxillofacial regions.

AIMS: To evaluate the radiation dose level during cone beam computed tomography (CBCT) scanning for the different oral and maxillofacial regions with and without thyroid collar shielding. MATERIALS AND METHODS: Average tissue-absorbed dose for a DCT PRO CBCT was measured using thermoluminescent dosimeter chips in a phantom with or without applying thyroid collars. Effective organ dose and total effective dose were derived using International Commission on Radiological Protection (ICRP) 2007 recommendations. RESULTS: The total effective doses for large, middle and small field of view (FOV) were 254.3 µSv, 249.0 µSv and 180.3 µSv, respectively, when no thyroid collar was used. Applying one thyroid collar around the front neck can reduce the total effective doses to 208.5 µSv (18.0% reduction), 149.1 µSv (40.1% reduction) and 110.5 µSv (38.7% reduction), respectively. When two thyroid collars were used around the front and back neck, the total effective doses were reduced to 219.1 µSv (13.8% reduction), 142.0 µSv (43.0% reduction) and 105.5 µSv (41.5% reduction), respectively. CONCLUSIONS: Thyroid collar can reduce the radiation dose during CBCT scanning for the oral and maxillofacial regions. The dose reduction becomes more significant when middle or small FOV is chosen.

The detection accuracies for proximal caries by cone-beam computerized tomography, film, and phosphor plates.

OBJECTIVES: To evaluate the accuracy of cone-beam computerized tomography (CBCT) for the detection of noncavitated proximal caries and to compare the detection accuracies of 2 CBCT imaging systems with those based on plain-film radiographs and phosphor-plate images. STUDY DESIGN: Test radiographs of 39 noncavitated unrestored human permanent teeth were obtained with film, phosphor-plate, ProMax 3D, and Kodak 9000 3D imaging systems. Seven observers used a 5-level scale to evaluate test images for the presence of proximal caries. With histologic examination serving as the reference standard, observer performances were assessed with receiver operating characteristic (ROC) curves, and the areas under the ROC curves (A(z) values) for the observers, and modalities were analyzed with a repeated-measures analysis of variance. RESULTS: The mean A(z) values for film, phosphor plates, ProMax 3D, and Kodak 9000 3D imaging systems were 0.541, 0.523, 0.528, and 0.525, respectively (P = .763). CONCLUSION: For detecting subtle noncavitated proximal caries, the detection accuracy with the CBCT images was little better than chance performance and was similar to that with phosphor plate- and film-based intraoral images.

Detection accuracy of in vitro approximal caries by cone beam computed tomography images.

AIMS: To evaluate the diagnostic accuracy of approximal carious lesions among five CBCT systems and to assess the effect of detector types employed by different CBCT systems on the accuracy of approximal caries diagnosis. MATERIALS AND METHODS: Thirty-nine extracted non-cavitated human permanent teeth were employed in the study. Seven observers evaluated 78 approximal surfaces of the teeth with respect to caries by the images from the following five CBCT systems: (1) NewTom 9000; (2) Accuitomo 3DX; (3) Kodak 9000 3D; (4) ProMax 3D; and (5) DCT PRO, respectively. The lesions were validated by histological examination. The area under receiver operating characteristic (ROC) curve (A(z)) was used to evaluate the diagnostic accuracy. RESULTS: Microscopy of approximal surfaces found 47.4% sound, 39.8% enamel and 12.8% dentin lesions. The differences of A(z) values among the five CBCT systems were not statistically significant (p=0.348). No significant difference was found between the two detector types of CBCT systems (p=0.47). CONCLUSIONS: The five CBCT systems employed in the study showed no significant difference in the in vitro approximal caries detection. Neither the detector nor the FOV employed by the CBCT systems has an impact on the detection accuracy of approximal caries.

[Comparative dosimetry of dental cone-beam computed tomography and multi-slice computed tomography for oral and maxillofacial radiology].

OBJECTIVE: To compare the effective radiation dose levels of cone beam computed tomography (CBCT) with those of multi-slice computed tomography (MSCT) when scanning the same maxillofacial regions. METHODS: The effective doses of 2 CBCT (NewTom 9000 and DCT Pro) and 1 MSCT (bright speed edge select 8 slice) scanners were calculated using thermoluminescent dosimeters (TLD) that were placed in a head and neck phantom, and expressed according to the International Commission on Radiation Protection (ICRP) 2007 guidelines. RESULTS: Effective dose values ranged from 41.8 to 249.1 µSv for CBCT. The doses of MSCT scanning for maxilla, mandible and maxilla + mandible were 506.7, 829.9 and 1066.1 µSv, respectively. Dose levels of scanning only for maxilla or mandible were significantly lower than those for maxilla + mandible. CONCLUSIONS: When scanning the same maxillofacial regions, the dose levels for NewTom 9000 and DCT Pro CBCT images were lower than those for Bright speed edge select 8 slice MSCT images. Dose levels reduction could be obtained when smaller regions were scanned.

Effective radiation dose of ProMax 3D cone-beam computerized tomography scanner with different dental protocols.

OBJECTIVES: The aim of this study was to compare effective doses resulting from different scan protocols for cone-beam computerized tomography (CBCT) using International Commission on Radiological Protection (ICRP) 1990 and 2007 calculations of dose. STUDY DESIGN: Average tissue-absorbed dose, equivalent dose, and effective dose for a ProMax 3D CBCT with different dental protocols were calculated using thermoluminescent dosimeter chips in a human equivalent phantom. Effective doses were derived using ICRP 1990 and the superseding 2007 recommendations. RESULTS: Effective doses (ICRP 2007) for default patient sizes from small to large ranged from 102 to 298 µSv. The coefficient of determination (R(2)) between tube current and effective dose (ICRP 2007) was 0.90. When scanning with lower resolution settings, the effective doses were reduced significantly (P < .05). CONCLUSIONS: ProMax 3D can provide a wide range of radiation dose levels. Reduction in radiation dose can be achieved when using lower settings of exposure parameters.

[Effect of radiation on the activity and expression of Ca(2+)-Mg(2+)-ATPase in rat masseter muscle].

OBJECTIVE: To investigate the activity and expression of Ca(2+)-Mg(2+)-ATPase in irradiated rat masseter muscle. METHODS: The rats were irradiated locally with a single dose of 20 Gy X-ray. The activities of Ca(2+)-Mg(2+)-ATPase were measured with colorimetric method. The protein expression of Ca(2+)-Mg(2+)-ATPase was determined by Western blotting and immunohistochemistry. RESULTS: The activities of Ca(2+)-Mg(2+)-ATPase in masseter muscle decreased by approximately 20% and 40% in irradiated rats on days 3 and 30 postirradiation. There was significant difference in the expression of Ca(2+)-Mg(2+)-ATPase protein between irradiated and nonirradiated rats on day 30 postirradiation. Ca(2+)-Mg(2+)-ATPase protein was found in the cytoplasm of masseter muscle. CONCLUSIONS: The decrease of ATPase activity played an important role in the cause of radiation-induced skeletal muscle injury, while there was no significant reduction in the expression of Ca(2+)-Mg(2+)-ATPase protein in irradiated rat masseter muscle.