The 4D virtual patient: A proof of concept in digital dentistry.

This dental technique article updates the 3-dimensional (3D) virtual patient digital workflow by introducing the space-time information acquired with jaw tracking motion. The direct digital procedure involved scanning the interim prostheses, creating virtual casts, and transferring the digital facebow, virtual articulation, and jaw-tracking motion. All 3D files and records from the intraoral scanner, cone beam computed tomography, extraoral scanner, and jaw tracking motion were superimposed using existing teeth as the connecting link in all data sets and adopting the best-fit alignment. The main advantages of the technique were creating a 4-dimensional virtual patient and standardizing the introduction of clinical space-time information (the fourth dimension) beyond the static condition.

Diamond-Like Carbon Coating Reduces Connection Screw Head Stripping After Multiple Tightening Instances.

The stability of implant-abutment joint is fundamental for the long-term success of implant rehabilitation. The screw loosening, fracture, and head deformation are among the most common mechanical complications. Several surface treatments of titanium screws have been proposed to improve their resistance and stability. Diamond-like carbon (DLC) coating of the materials is widely used to increase their wear resistance and durability. The present study aimed to evaluate the effect of carbon fiber coating on the screw head on screw removal torque and screw head stripping. One hundred titanium implant screws were used, 50 without coating (Group 1) and 50 with DLC coating of the screw head (Group 2). Each screw was tightened with a torque of 25 Ncm and unscrewed 10 times. The removal torque was measured with a digital cap torque tester for each loosening. Optical 3d measurement of the screw head surface was performed by a fully automatic machine before and after multiple tightening to investigate surface modifications. The reverse torque values decreased with repeated tightening and loosening cycles in both groups without significant differences (P > .05). Optical measurements of surface dimensions revealed average changes of 0.0357 mm in Group 1 and 0.02312 mm in Group 2, which resulted to be statistically significant (P < .001). The DLC coating of the retention screw head can prevent its distortion and wear, especially after multiple tightening.

Gleditsiae fructus regulates osteoclastogenesis by inhibiting the c­Fos/NFATc1 pathway and alleviating bone loss in an ovariectomy model.

Medical and economic developments have allowed the human lifespan to extend and, as a result, the elderly population has increased worldwide. Osteoporosis is a common geriatric disease that has no symptoms and even a small impact can cause fractures in patients, leading to a serious deterioration in the quality of life. Osteoporosis treatment typically involves bisphosphonates and selective estrogen receptor modulators. However, these treatments are known to cause severe side effects, such as mandibular osteonecrosis and breast cancer, if used for an extended period of time. Therefore, it is essential to develop therapeutic agents from natural products that have fewer side effects. Gleditsiae fructus (GF) is a dried or immature fruit of Gleditsia sinensis Lam. and is composed of various triterpenoid saponins. The anti­inflammatory effect of GF has been confirmed in various diseases, and since the anti­inflammatory effect plays a major role in inhibiting osteoclast differentiation, GF was expected to be effective in osteoclast differentiation and menopausal osteoporosis; however, to the best of our knowledge, it has not yet been studied. Therefore, the present study was designed to examine the effect of GF on osteoclastogenesis and to investigate the mechanism underlying inhibition of osteoclast differentiation. The effects of GF on osteoclastogenesis were determined in vitro by tartrate­resistant acid phosphatase (TRAP) staining, pit formation assays, filamentous actin (F­actin) ring formation assays, western blotting and reverse transcription­quantitative PCR analyses. Furthermore, the administration of GF to an animal model exhibiting menopausal osteoporosis allowed for the analysis of alterations in the bone microstructure of the femur using micro­CT. Additionally, assessments of femoral tissue and serum were conducted. The present study revealed that the administration of GF resulted in a reduction in osteoclast levels, F­actin rings, TRAP activity and pit area. Furthermore, GF showed a dose­dependent suppression of nuclear factor of activated T­cells cytoplasmic, c­Fos and other osteoclastogenesis­related markers.

Immediate loading full-arch rehabilitation using transmucosal tissue-level implants with different variables associated: a one-year observational study.

BACKGROUND: The aim of the present observational study was to investigate the application of transmucosal tissue-level implants in immediate loading full-arch rehabilitation with different variables associated. METHODS: Patients needing a full-arch implant rehabilitation were recruited and rehabilitated with four transmucosal tissue level implants. Data related to implants' diameters and lengths, jaw distributions, and presence of angulated abutments were collected. The following outcomes were evaluated: survival rate, marginal bone loss (MBL), Plaque Index (PI), bleeding on probing (BoP), probing depth (PD). Descriptive statistical analysis was reported and univariate linear regression models were built to assess a significant correlation between MBL and the different implant related factors. RESULTS: Twenty patients were rehabilitated for a total implant number of 80; 11 rehabilitations were performed on the maxilla, while 9 were performed on the mandible; 48 implants presented a 3.8 mm diameter and 32 implants presented a 4.25 mm diameter. Implants length varied between 10 to 15 mm; 40 tilted implants were connected to angulated abutment, while 40 straight implants were connected directly to the prostheses (no abutments). At the one year follow-up visit no implants failed resulting in an implant survival rate of 100%. The overall MBL was 1.19±0.30 mm. No statistically significant difference (P>0.05) was highlighted among any of the subgroups analyzed. CONCLUSIONS: Despite different variables associated, tissue level implants seem to represent a valid option when applied in immediate loading full-arch rehabilitation. Further research and longer observational periods are encouraged to confirm the result.

Finding of Novel Galactose Utilizing Halomonas sp. YK44 for Polyhydroxybutyrate (PHB) Production.

Polyhydroxybutyrate (PHB) is a biodegradable bioplastic with potential applications as an alternative to petroleum-based plastics. However, efficient PHB production remains difficult. The main cost of PHB production is attributed to carbon sources; hence, finding inexpensive sources is important. Galactose is a possible substrate for polyhydroxyalkanoate production as it is abundant in marine environments. Marine bacteria that produce PHB from galactose could be an effective resource that can be used for efficient PHB production. In this study, to identify a galactose utilizing PHB producer, we examined 16 Halomonas strains. We demonstrated that Halomonas cerina (Halomonas sp. YK44) has the highest growth and PHB production using a culture media containing 2% galactose, final 4% NaCl, and 0.1% yeast extract. These culture conditions yielded 8.98 g/L PHB (78.1% PHB content (w/w)). When galactose-containing red algae (Eucheuma spinosum) hydrolysates were used as a carbon source, 5.2 g/L PHB was produced with 1.425% galactose after treatment with activated carbon. Since high salt conditions can be used to avoid sterilization, we examined whether Halomonas sp. YK44 could produce PHB in non-sterilized conditions. Culture media in these conditions yielded 72.41% PHB content. Thus, Halomonas sp. YK44 is robust against contamination, allowing for long-term culture and economical PHB production.

Acceleration of Polybutylene Succinate Biodegradation by Terribacillus sp. JY49 Isolated from a Marine Environment.

Polybutylene succinate (PBS) is a bioplastic substitute for synthetic plastics that are made from petroleum-based products such as polyethylene and polypropylene. However, the biodegradation rate of PBS is still low and similar to that of polylactic acid (PLA). Moreover, our knowledge about degrader species is limited to a few fungi and mixed consortia. Here, to identify a bacterial degrader to accelerate PBS degradation, we screened and isolated Terribacillus sp. JY49, which showed significant degradability. In order to optimize solid and liquid culture conditions, the effect of factors such as temperature, additional carbon sources, and salt concentrations on degradation was confirmed. We observed a degradation yield of 22.3% after 7 days when adding 1% of glucose. Additionally, NaCl was added to liquid media, and degradation yield was decreased but PBS films were broken into pieces. Comparing the degree of PBS degradation during 10 days, the degradation yield was 31.4% after 10 days at 30 °C. Alteration of physical properties of films was analyzed by using scanning electron microscopy (SEM), gel permeation chromatography (GPC), and Fourier transform infrared (FT-IR). In addition, Terribacillus sp. JY49 showed clear zones on poly(butylene adipate-co-terephthalate) (PBAT), polycaprolactone (PCL), and copolymers such as P(3HB-co-3HV) and P(3HV-co-4HB), exhibiting a broad spectrum of degradation activities on bioplastics. However, there was no significant difference in absorbance when esterase activity was examined for different types of bioplastics. Overall, Terribacillus sp. JY49 is a potential bacterial strain that can degrade PBS and other bioplastics, and this is the first report of Terribacillus sp. as a bioplastic degrader.

Finding a Benign Plasticizer to Enhance the Microbial Degradation of Polyhydroxybutyrate (PHB) Evaluated by PHB Degrader Microbulbifer sp. SOL66.

As a biodegradable plastic, polyhydroxybutyrate (PHB) has relatively poor mechanical properties, preventing its wider use. Various plasticizers have been studied to improve the mechanical properties of PHB; however, due to the slow degradation speed in the soil environment and lack of evaluation methods, studies on the degradation of PHB with plasticizers are rarely reported. In this study, by applying Microbulbifer sp. SOL66, which is able to degrade PHB very quickly, a benign plasticizer was evaluated with good properties and good degradability, not inhibiting microbial activities. Eight different plasticizers were applied with PHB and Microbulbifer sp. SOL66, PHB film containing 10% and 20% tributyl citrate showed significant biodegradability of PHB. It was confirmed that tributyl citrate could increase the speed of PHB degradation by Microbulbifer sp. SOL66 by 88% at 1 day, although the degree of degradation was similar after 3 days with and without tributyl citrate. By the analysis of microbial degradation, physical, chemical, and mechanical properties, tributyl citrate was shown not only to improve physical, chemical, and mechanical properties but also the speed of microbial degradation.

Simultaneous monitoring of each component on degradation of blended bioplastic using gas chromatography-mass spectrometry.

The increasing interest in bioplastics, with regard to future environmental issues, has rendered research on bioplastic biodegradation highly important. However, only a few tools directly monitor the degradation of bioplastics without measuring the levels of gaseous products, such as carbon dioxide. Classical nonquantitative methods, such as clear zone tests on solid plates, and less-sensitive weight-loss experiments in liquid media measured using a precision scale, are still employed to screen the microbial players associated with bioplastic degradation and monitor the biodegradation rates. However, the simultaneous monitoring of the degradation of each component of blended bioplastics has not been previously reported. In the present study, to provide information regarding the degradation rates and compositional changes of different bioplastics in a blend in a time-dependent manner, we simultaneously monitored and quantified the degradation of four bioplastics, polyhydroxybutyrate (PHB), polybutylene succinate (PBS), polycaprolactone (PCL), and poly(butylene adipate-co-terephthalate) (PBAT), by Bacillus sp. JY36 using gas chromatography-mass spectrometry (GC-MS) analysis after fatty acid methyl ester (FAME) derivatization. Our results demonstrate the feasibility of using the GC-MS-based method described here to obtain comprehensive data regarding blended bioplastics and their degradation. Moreover, our findings indicate that this method may support classical analytic tools for assessing bioplastic biodegradation.

4-Chloro-2-Isopropyl-5-Methylphenol Exhibits Antimicrobial and Adjuvant Activity against Methicillin-Resistant Staphylococcus aureus.

Methicillin-resistant Staphylococcus aureus (MRSA) causes severe infections and poses a global healthcare challenge. The utilization of novel molecules which confer synergistical effects to existing MRSA-directed antibiotics is one of the well-accepted strategies in lieu of de novo development of new antibiotics. Thymol is a key component of the essential oil of plants in the Thymus and Origanum genera. Despite the absence of antimicrobial potency, thymol is known to inhibit MRSA biofilm formation. However, the anti-MRSA activity of thymol analogs is not well characterized. Here, we assessed the antimicrobial activity of several thymol derivatives and found that 4-chloro-2-isopropyl-5-methylphenol (chlorothymol) has antimicrobial activity against MRSA and in addition it also prevents biofilm formation. Chlorothymol inhibited staphyloxanthin production, slowed MRSA motility, and altered bacterial cell density and size. This compound also showed a synergistic antimicrobial activity with oxacillin against highly resistant S. aureus clinical isolates and biofilms associated with these isolates. Our results demonstrate that chlorinated thymol derivatives should be considered as a new lead compound in anti-MRSA therapeutics.

Novel Poly(butylene adipate-co-terephthalate)-degrading Bacillus sp. JY35 from wastewater sludge and its broad degradation of various bioplastics.

Poly(butylene adipate-co-terephthalate) (PBAT), a bioplastic consisting of aliphatic hydrocarbons and aromatic hydrocarbons, was developed to overcome the shortcomings of aliphatic and aromatic polyesters. Many studies report the use of PBAT as a blending material for improving properties of other bioplastics. However, there are few studies on microorganisms that degrade PBAT. We found six kinds of PBAT-degrading microorganisms from various soils. Among these, Bacillus sp. JY35 showed superior PBAT degradability and robustness to temperature. We monitored the degradation of PBAT films by Bacillus sp. JY35 using scanning electron microscopy, field emission scanning electron microscopy, Fourier-transform infrared spectroscopy, and gel permeation chromatography. GC-MS was used to measure the PBAT film degradation rate at different temperatures and with additional NaCl and carbon sources. Certain additional carbon sources improve the growth of Bacillus sp. JY35. However, this did not increase PBAT film degradation. Time-dependent PBAT film degradation rates were measured during three weeks of cultivation, after which the strain achieved almost 50% degradation. Additionally, various bioplastics were applied to solid cultures to confirm the biodegradation range of Bacillus sp. JY35, which can degrade not only PBAT but also PBS, PCL, PLA, PHB, P(3HB-co-4HB), P(3HB-co-3HV), P(3HB-co-3HHx), and P(3HB-co-3HV-co-3HHx), suggesting its usability as a superior bioplastic degrader.

MLL5, a histone modifying enzyme, regulates androgen receptor activity in prostate cancer cells by recruiting co-regulators, HCF1 and SET1.

In prostate cancer, the androgen receptor (AR) transcription factor is a major regulator of cell proliferation and metastasis. To identify new AR regulators, we focused on Mixed lineage leukemia 5 (MLL5), a histone-regulating enzyme, because significantly higher MLL5 expression was detected in prostate cancer tissues than in matching normal tissues. When we expressed shRNAs targeting MLL5 gene in prostate cancer cell line, the growth rate and AR activity were reduced compared to those in control cells, and migration ability of the knockdown cells was reduced significantly. To determine the molecular mechanisms of MLL5 on AR activity, we proved that AR physically interacted with MLL5 and other co-factors, including SET-1 and HCF-1, using an immunoprecipitation method. The chromatin immunoprecipitation analysis showed reduced binding of MLL5, co-factors, and AR enzymes to AR target gene promoters in MLL5 shRNA-expressing cells. Histone H3K4 methylation on the AR target gene promoters was reduced, and H3K9 methylation at the same site was increased in MLL5 knockdown cells. Finally, xenograft tumor formation revealed that reduction of MLL5 in prostate cancer cells retarded tumor growth. Our results thus demonstrate the important role of MLL5 as a new epigenetic regulator of AR in prostate cancer. [BMB Reports 2020; 53(12): 634-639].

Histone Demethylase LSD1 Regulates Kidney Cancer Progression by Modulating Androgen Receptor Activity.

Kidney cancer is one of the most difficult cancers to treat by targeted and radiation therapy. Therefore, identifying key regulators in this cancer is especially important for finding new drugs. We focused on androgen receptor (AR) regulation by its epigenetic co-regulator lysine-specific histone demethylase 1 (LSD1) in kidney cancer development. LSD1 knock-down in kidney cancer cells decreased expression of AR target genes. Moreover, the binding of AR to target gene promoters was reduced and histone methylation status was changed in LSD1 knock-down kidney cancer cells. LSD1 knock-down also slowed growth and decreased the migration ability of kidney cancer cells. We found that pargyline, known as a LSD1 inhibitor, can reduce AR activity in kidney cancer cells. The treatment of kidney cancer cells with pargyline delayed growth and repressed epithelial-mesenchymal transition (EMT) markers. These effects were additively enhanced by co-treatment with the AR inhibitor enzalutamide. Down-regulation of LSD1 in renal cancer cells (RCC) attenuated in vivo tumor growth in a xenograft mouse model. These results provide evidence that LSD1 can regulate kidney cancer cell growth via epigenetic control of AR transcription factors and that LSD1 inhibitors may be good candidate drugs for treating kidney cancer.

Histone Demethylase KDM7A Regulates Androgen Receptor Activity, and Its Chemical Inhibitor TC-E 5002 Overcomes Cisplatin-Resistance in Bladder Cancer Cells.

Histone demethylase KDM7A regulates many biological processes, including differentiation, development, and the growth of several cancer cells. Here, we have focused on the role of KDM7A in bladder cancer cells, especially under drug-resistant conditions. When the KDM7A gene was knocked down, bladder cancer cell lines showed impaired cell growth, increased cell death, and reduced rates of cell migration. Biochemical studies revealed that KDM7A knockdown in the bladder cancer cells repressed the activity of androgen receptor (AR) through epigenetic regulation. When we developed a cisplatin-resistant bladder cancer cell line, we found that AR expression was highly elevated. Upon treatment with TC-E 5002, a chemical inhibitor of KDM7A, the cisplatin-resistant bladder cancer cells, showed decreased cell proliferation. In the mouse xenograft model, KDM7A knockdown or treatment with its inhibitor reduced the growth of the bladder tumor. We also observed the upregulation of KDM7A expression in patients with bladder cancer. The findings suggest that histone demethylase KDM7A mediates the growth of bladder cancer. Moreover, our findings highlight the therapeutic potential of the KMD7A inhibitor, TC-E 5002, in patients with cisplatin-resistant bladder cancer.

Rapid and Sensitive Determination of HIV-1 Virus Based on Surface Enhanced Raman Spectroscopy.

In this study, rapid and sensitive detection of human immunodeficiency virus (HIV)-1 was performed based on immunoreactions with an Au nanodot fabricated indium tin oxide (ITO) substrate using surface-enhanced Raman spectroscopy (SERS). Highly ordered Au nanodots (ca. 20 nm) were electrochemically fabricated over a large surface area (20 mm x 10 mm) of an ITO substrate using a simple deposition method with Triton X-100. On the Au nanodot surface, monoclonal antibody fragments against gp120 were selectively bound by gold-sulfur interactions. Various concentrations (35 fg/mL to 350 pg/mL) of HIV-1 virus-like particles (HIV-1 VLPs) were used for the measurements. The presence of HIV-1 VLPs was rapidly (within 5 s) and successfully determined by SERS due to specific immunoreactions on the Au nanodots without the use of labeling probes. The results showed the possibility of using SERS-related methods as a new immunoassay for the study of biomolecular interactions and detection of low viral loads. Moreover, based on its high sensitivity and chemical specificity, SERS could be used as a promising clinical tool for detecting infectious small biological components.

Highly Sensitive Electrical Detection of HIV-1 Virus Based on Scanning Tunneling Microscopy.

A highly sensitive immunosensor based on scanning tunneling microscopy (STM) was developed for the first time to detect living material such as HIV-1 virus by gold (Au) nanoparticle and fragmented antibody complex. Fragmented antibodies were pre-immobilized on the Au surface, then HIV-1 virus like particles (HIV-1 VLPs) and Au-nanoparticle and fragmented antibody complexes were applied to develop sandwich assay. The developed surface morphology and the current profile of fabricated immunosensing element were characterized by Raman spectroscopy and investigated with STM. The power spectrum derived from the current profile was found to be related with concentrations of HIV-1 VLPs. Using the electrical detection method based on current mapping profile of STM, living material such as virus, HIV-1 VLPs, was able to be detected successfully. The proposed technique can be a promising method to construct the highly sensitive and efficient sensor for detecting viruses and other living materials.

Alteromonas confluentis sp. nov., isolated from the junction between the ocean and a freshwater spring.

A Gram-stain-negative, aerobic, non-spore-forming, non-flagellated and coccoid, ovoid or rod-shaped bacterial strain, DSSK2-12T, was isolated from the place where the ocean and a freshwater spring meet at Jeju island, South Korea. Strain DSSK2-12T grew optimally at 30 °C, at pH 7.0­8.0 and in the presence of 2.0 % (w/v) NaCl. The neighbour-joining phylogenetic tree based on 16S rRNA gene sequences revealed that strain DSSK2-12T fell within the clade comprising the type strains of species of the genus Alteromonas. Strain DSSK2-12T exhibited 16S rRNA gene sequence similarity values of 97.2­98.1 % to the type strains of Alteromonas litorea, Alteromonas marina, Alteromonas hispanica and Alteromonas genovensis and of 95.39­96.98 % to those of other species of the genus Alteromonas. Strain DSSK2-12T contained Q-8 as the predominant ubiquinone and summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c), C16 : 0 and C18 : 1ω7c as the major fatty acids. The major polar lipids of strain DSSK2-12T were phosphatidylethanolamine, phosphatidylglycerol and one unidentified aminolipid. The DNA G+C content of strain DSSK2-12T was 48.6 mol% and its mean DNA­DNA relatedness values with the type strains of A. litorea, A. marina, A. hispanica and A. genovensis were 9­21 %. The differential phenotypic properties, together with phylogenetic and genetic distinctiveness, revealed that strain DSSK2-12T is separated from other species of the genus Alteromonas. On the basis of the data presented, strain DSSK2-12T is considered to represent a novel species of the genus Alteromonas, for which the name Alteromonas confluentis sp. nov. is proposed. The type strain is DSSK2-12T ( = KCTC 42603T = CECT 8870T).

Pseudohalocynthiibacter aestuariivivens gen. nov., sp. nov., isolated from a tidal flat.

A Gram-stain-negative, non-motile, aerobic and coccoid, ovoid or rod-shaped bacterial strain, designated BS-W9(T), was isolated from a tidal flat of the South Sea, South Korea. Strain BS-W9(T) grew optimally at 25-30 °C, at pH 7.0-8.0 and in the presence of approximately 2.0% (w/v) NaCl. Phylogenetic trees, based on 16S rRNA gene sequences, revealed that strain BS-W9(T) clustered with the type strain of Halocynthiibacter namhaensis , showing a highest sequence similarity of 97.3%. It exhibited sequence similarity values of less than 95.6% to the type strains of other species with validly published names. Strain BS-W9(T) contained Q-10 as the predominant ubiquinone and C18:1ω7c as the predominant fatty acid. The major polar lipids of strain BS-W9(T) were phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, one unidentified lipid and one unidentified aminolipid. The fatty acid and polar lipid profiles of strain BS-W9(T) were distinguished from those of the type strains of H. namhaensis and other phylogenetically related genera. The DNA G+C content of strain BS-W9(T) was 53.2 mol% and its mean DNA-DNA relatedness value with H. namhaensis RA2-3(T) was 14%. On the basis of the phylogenetic, chemotaxonomic and other phenotypic properties, strain BS-W9(T) is considered to represent a novel genus and species within the family Rhodobacteraceae , for which the name Pseudohalocyntiibacter aestuariivivens gen. nov., sp. nov. is proposed. The type strain of Pseudohalocyntiibacter aestuariivivens is BS-W9(T) ( =KCTC 42348(T) =CECT 8726(T)).

Evaluation of radiofrequency exposure levels from multiple wireless installations in population dense areas in Korea.

This paper presents the results of measurements from simultaneous human exposure to various radiofrequency (RF) signals at densely populated areas. Measurements were performed at 1260 positions across Korea to determine exposure compliance to electromagnetic fields for the general public. The measured exposure levels were very low compared with the international exposure guidelines and Korean human protection notice. The highest total exposure ratio was 5.1 × 10(-3) (approximately 7.1% of guideline limits).

Anti-obesity effects of black ginseng extract in high fat diet-fed mice.

Black ginseng is produced by a repeated steaming process. The aim of this study was to investigate the anti-obesity effects of black ginseng ethanol extract (BG-EE) in high fat (HF) diet-fed mice. Two groups were fed either a normal control (NC) diet or a HF diet (45% kcal fat). The other three groups were given a HF diet supplemented with 1% BG-EE, 3% BG-EE, and 5% BG-EE for 12 wk. The anti-obesity effects of the BG-EE supplement on body weight, the development of fat mass, and lipid mechanisms were assessed in obese mice. HF-induced hyperlipidemia, fat accumulation in the liver, and white adipose tissues were reduced after BG-EE supplementation. Total fecal weight and the amount of fecal fat excretion also were increased after BG-EE supplementation. These results suggest that BG-EE may be useful to ameliorate HF-induced obesity through the strong inhibition of fat digestion.

Effects of whole-body exposure to 915 MHz RFID on secretory functions of the thyroid system in rats.

As a part of an investigation on the potential risks of radiofrequency identification (RFID) on human health, we studied whether exposure to 915 MHz RFID in rats significantly affected the secretory function of the thyroid system. A reverberation chamber was used as a whole-body exposure system. Male Sprague-Dawley rats were exposed for 8 h per day, 5 days per week, for a duration of 2, 4, 8, or 16 weeks. The estimated whole-body average specific absorption rate (SAR) varied from 3.2 to 4.6 W/kg depending on the age/mass of the animals for the field of the 915 MHz RFID reader. Plasma levels of triiodothyronine (T3), thyroxine (T4), and thyroid-stimulating hormone (TSH) were evaluated via enzyme-linked immunosorbent assay. Morphological changes in the thyroid gland were then analyzed. No changes in T3, T4, or TSH were observed over time between the sham- and RFID-exposed groups. We suggest that subchronic exposure to 915 MHz RFID at a SAR of 4 W/kg does not cause significant effects on thyroid secretory function.