A theoretical study on toluene oxidization by OH radical.

Toluene, a prominent member of volatile organic compounds (VOCs), exerts a substantial adverse influence on both human life and the environment. In the context of advanced oxidation processes, the ·OH radical emerges as a highly efficient oxidant, pivotal in the elimination of VOCs. This study employs computational quantum chemistry methods (G4MP2//B3LYP/6-311++G(d,p)) to systematically investigate the degradation of toluene by ·OH radicals in an implicit solvent model, and validates the rationale of choosing a single-reference method using T1 diagnostics. Our results suggest three possible reaction mechanisms for the oxidation of toluene by ·OH: firstly, the phenyl ring undergoes a hydrogen abstraction reaction followed by direct combination with ·OH to form cresol; secondly, ·OH directly adds to the phenyl ring, leading to ring opening; thirdly, oxidation of sidechain to benzoic acid followed by further addition and ring opening. The last two oxidation pathways involve the ring opening of toluene via the addition of ·OH, significantly facilitating the process. Therefore, both pathways are considered feasible for the degradation of toluene. Subsequently, the UV-H2O2 system was designed to induce the formation of ·OH for toluene degradation and to identify the optimal reaction conditions. It was demonstrated that ·OH and 1O2 are the primary active species for degrading toluene, with their contribution ranking as ·OH > 1O2. The intermediates in the mixture solution after reactions were characterized using GC-MS, demonstrating the validity of theoretical predictions. A comparative study of the toluene consumption rate revealed an experimental comprehensive activation energy of 10.33 kJ/mol, which is consistent with the preliminary activation energies obtained via theoretical analysis of these three mechanisms (0.56 kJ/mol to 13.66 kJ/mol), indicating that this theoretical method can provide a theoretical basis for experimental studies on the oxidation of toluene by ·OH.

Pathological features and molecular signatures of early olfactory dysfunction in 3xTg-AD model mice.

BACKGROUND: Olfactory dysfunction is known to be an early manifestation of Alzheimer's disease (AD). However, the underlying mechanism, particularly the specific molecular events that occur during the early stages of olfactory disorders, remains unclear. METHODS: In this study, we utilized transcriptomic sequencing, bioinformatics analysis, and biochemical detection to investigate the specific pathological and molecular characteristics of the olfactory bulb (OB) in 4-month-old male triple transgenic 3xTg-AD mice (PS1M146V/APPSwe/TauP301L). RESULTS: Initially, during the early stages of olfactory impairment, no significant learning and memory deficits were observed. Correspondingly, we observed significant accumulation of amyloid-beta (Aß) and Tau pathology specifically in the OB, but not in the hippocampus. In addition, significant axonal morphological defects were detected in the olfactory bulb, cortex, and hippocampal brain regions of 3xTg-AD mice. Transcriptomic analysis revealed a significant increase in the expression of neuroinflammation-related genes, accompanied by a significant decrease in neuronal activity-related genes in the OB. Moreover, immunofluorescence and immunoblotting demonstrated an activation of glial cell biomarkers Iba1 and GFAP, along with a reduction in the expression levels of neuronal activity-related molecules Nr4a2 and FosB, as well as olfaction-related marker OMP. CONCLUSION: In sum, the early accumulation of Aß and Tau pathology induces neuroinflammation, which subsequently leads to a decrease in neuronal activity within the OB, causing axonal transport deficits that contribute to olfactory disorders. Nr4a2 and FosB appear to be promising targets for intervention aimed at improving early olfactory impairment in AD.

Antibody-Mediated Nanodrug of Proteasome Inhibitor Carfilzomib Boosts the Treatment of Multiple Myeloma.

Multiple myeloma (MM) is the second most common hematological malignancy. For relapsed and refractory MM, a proteasome inhibitor, carfilzomib (CFZ), has become one of the few clinical options. CFZ suffers, nevertheless, metabolic instability and poor bioavailability and may induce severe cardiovascular and renal adverse events. Here, we report that daratumumab (Dar)-decorated polypeptide micelles (Dar-PMs) mediate the targeted delivery of CFZ to CD38-positive MM, effectively boosting its anti-MM efficacy. CFZ-loaded Dar-PMs (Dar-PMs-CFZ) exhibited an average diameter of ca. 80 nm and Dar density-dependent cell endocytosis and anti-MM activity, in which over 6-fold greater inhibitory effect to LP-1 and MM.1S MM cells than nontargeted PMs-CFZ control was achieved at a Dar density of 3.2 (Dar3.2-PMs-CFZ). Interestingly, Dar3.2-PMs-CFZ markedly enhanced the growth inhibition of orthotopic LP-1 MM in mice and significantly extended the median survival time compared with PMs-CFZ and free CFZ (95 days vs 60 and 54 days, respectively). In line with its high MM targetability and anti-MM efficacy, Dar3.2-PMs-CFZ revealed little toxic effects and effectively prevented osteolytic lesions. The antibody-targeted nanodelivery of a proteasome inhibitor appears to be an appealing strategy to treat multiple myeloma.

Integrated transcriptomics reveals the brain and blood biomarkers in Alzheimer's disease.

BACKGROUND: The systematic molecular associations between the peripheral blood cells and brain in Alzheimer's disease (AD) remains unclear, which hinders our understanding of AD pathological mechanisms and the exploration of new diagnostic biomarkers. METHODS: Here, we performed an integrated analysis of the brain and peripheral blood cells transcriptomics to establish peripheral biomarkers of AD. By employing multiple statistical analyses plus machine learning, we identified and validated multiple regulated central and peripheral network in patients with AD. RESULTS: By bioinformatics analysis, a total of 243 genes were differentially expressed in the central and peripheral systems, mainly enriched in three modules: immune response, glucose metabolism and lysosome. In addition, lysosome related gene ATP6V1E1 and immune response related genes (IL2RG, OSM, EVI2B TNFRSF1A, CXCR4, STAT5A) were significantly correlated with Aß or Tau pathology. Finally, receiver operating characteristic (ROC) analysis revealed that ATP6V1E1 showed high-diagnostic potential for AD. CONCLUSION: Taken together, our data identified the main pathological pathways in AD progression, particularly the systemic dysregulation of the immune response, and provided peripheral biomarkers for AD diagnosis.

Removal and Recovery of Gaseous Elemental Mercury Using a Cl-Doped Protonated Polypyrrole@MWCNTs Composite Membrane.

Due to the restrictions on mercury mining, recovering the mercury from mercury-containing waste is attracting increasing attention. This study successfully achieved the removal and recovery of gaseous elemental mercury (Hg0) by using membrane technology. A novel composite membrane of Cl-doped protonated polypyrrole-coated multiwall carbon nanotubes (Cl-PPy@MWCNTs) was fabricated in which MWCNTs acted as the framework to support the active component Cl-PPy. The morphology, structure, and composition of the prepared membranes were determined by field emission scanning electron microcopy, energy-dispersive spectroscopy, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, etc. The composite membrane exhibited an excellent performance in Hg0 removal (97.3%) at a high space velocity of 200,000 h-1. The dynamical adsorption capacity of Hg0 was 3.87 mg/g when the Hg0 breakthrough reached 10%. The adsorbed Hg0 could be recovered/enriched via a leaching process using acidic NaCl solution; meanwhile, the membrane was regenerated. The recovered mercury was identified in the form of Hg2+, with a recovery efficiency of over 99%. Density functional theory calculations and mechanism analysis clarified that the electrons of Hg0 transported to the delocalized electron orbits of protonated PPy and then combined with Cl- to form Hg2Cl2/HgCl2. Finally, we first demonstrated that the analogous protonated conductive polymers (e.g., polyaniline) also possessed good Hg0 removal ability, implying that such species may offer more outstanding answers and attract attention in future.

Risk Factors for Outcomes After Microvascular Decompression for Trigeminal Neuralgia.

BACKGROUND: Microvascular decompression (MVD) has been the most effective long-term surgical treatment of trigeminal neuralgia (TN). However, the risk factors for poor pain control after MVD are not fully understood. METHODS: A total of 184 patients with typical TN who had undergone MVD at our institution from January 3, 2008 to January 3, 2016 were enrolled in the present study. The data were collected from the electronic operative records and case notes and retrospectively analyzed. Patients were followed up at the outpatient department or by telephone at a minimum of 3 months and a maximum of 48 months postoperatively. RESULTS: Of the 184 patients enrolled in the present study, 72.3% had had freedom from pain after MVD and 27.7% had experienced poor pain control at the follow-up examinations (minimum, 3 months; maximum, 48 months). The risk factors for poor pain control after MVD using binary logistic regression and receiver operating characteristic curve analysis included younger age (odds ratio [OR], 0.90; 95% confidence interval [CI], 0.82-0.99; P = 0.028; area under the curve [AUC], 0.774), poor preoperative pain control (Barrow Neurological Institute score >IV; OR, 52.03; 95% CI, 6.44-420.16; P < 0.001; AUC, 0.858), intraoperatively detected multivessel compression (OR, 2.49; 95% CI, 3.10-46.59, P < 0.001; AUC, 0.871). Furthermore, combined compression of the superior cerebellar artery and petrosal vein was an independent risk factor predicting a poor outcome after MVD (OR, 5.69; 95% CI, 33.78-2579.03; P < 0.001; AUC, 0.812). CONCLUSIONS: Younger patients with TN had worse long-term pain outcomes after MVD. The additional factors associated with postoperative recurrence included poor preoperative pain control (Barrow Neurological Institute score >IV) and multivessel compression. Furthermore, combined compression of the superior cerebellar artery and petrosal vein was associated with worse outcomes.

Stereotactic Catheter Drainage Versus Conventional Craniotomy for Severe Spontaneous Intracerebral Hemorrhage in the Basal Ganglia.

Intracerebral hemorrhage (ICH) is one of the most devastating forms of cerebrovascular pathology. However, its treatment remains a matter of debate among neurosurgeons and neurologists. The study was to explore the efficacy of minimally invasive surgery (stereotactic catheter drainage, SCD) for patients with severe intracerebral hemorrhage (Glasgow Coma Scale, GCS) score ≤ 8 and hematoma volume ≥ 30 cm3) and to determine predisposing factors for good clinical outcome. A total of 75 patients with severe ICH were included in this retrospective study. Patients were assigned to the SCD group (n=38) or the conventional craniotomy group (n=37). Patients were followed up for 12 months postoperatively, and their clinical parameters were compared. During the operation, the SCD group exhibited a lower bleeding volume (p<0.001) and shorter operating time (p<0.001) than the conventional craniotomy group. For postoperative efficacy, the rates of pneumonia and tracheotomy were lower (p=0.002 and p=0.027, respectively), and the duration of hospital and neurosurgery intensive care unit (NSICU) in days were significantly shorter in the SCD group (p=0.046 and p=0.047, respectively). Furthermore, patients in the SCD group showed improved modified Rankin Scale (mRS) scores at discharge (p<0.018) and at 12-month follow up (p<0.001). Predisposing factors for good clinical outcomes were hematoma volume (<50 cm3, 95% confidence interval (CI): 1.043-1.956, p<0.046), initial GCS score (>6, 95% CI: 3.248-187.466, p<0.001), hypertension (none, 95% CI: 1.440-2.922, p<0.001), and treatment modality (SCD, 95% CI: 1.422-3.226, p<0.001). Taken together, SCD surgery is safe and effective in patients with severe ICH and has fewer complications and better clinical outcomes than conventional craniotomy.

Combustion behavior, emission characteristics of SO2, SO3 and NO, and in situ control of SO2 and NO during the co-combustion of anthracite and dried sawdust sludge.

The combustion behaviors of anthracite and dried sawmill sludge (DSS) were studied using thermogravimetric analysis (TGA) and derivative thermogravimetric analysis (DTG). DSS was found to be a promoter for anthracite combustion, the addition of DSS in anthracite decreased the burnout temperature and time. But DSS caused the rapid releases of SO2 and NO in the initial combustion stage. In overall, the increasing of DSS significantly decreased the emission factor of SO2 from 13.42 ±â€¯1.80 to 0.31 ±â€¯0.08 g/kg; while the emission factor of NO was not obviously changed and stable at 0.7-0.8 g/kg in all cases. The oxygen-rich atmosphere was helpful for the rapid and sufficient combustion of blend; the oxygen-lean atmosphere delayed the combustion process and slowed down the releases of SO2 and NO. The increasing combustion temperature improved the anthracite combustion, and the emission factors of SO2 and NO were all increased with the temperature increasing. 900 °C was found to be the best combustion temperature for NO generation. SO3 was detected in the combustion of anthracite under 21% and 30% of O2. Two promising ways for control of SO2 and NO were provided: 1) urea-fuel mixture combustion combined with the post-combustion wet absorption by Na2CO3; 2) post-combustion wet absorption by NaClO/Na2CO3. The removal efficiencies of SO2 and NO could reach 100% and over 95% respectively. The removal products were determined as sulfate, sulfite and nitrate by IC, with no toxic byproducts being produced.

The Clinical Efficacy of Electromagnetic Navigation-Guided Hematoma Puncture Drainage in Patients with Hypertensive Basal Ganglia Hemorrhage.

OBJECTIVE: To investigate the clinical efficacy of navigation-guided minimally invasive surgery in patients with hypertensive basal ganglia hemorrhage. METHODS: A total of 64 patients with hypertensive basal ganglia hemorrhage were enrolled in this retrospective study. They were divided into a navigation group and a traditional group based on surgical approaches. The data for the 2 groups of patients were analyzed with regard for the hematoma clearance rate, duration of surgery, duration of hospitalization, Glasgow Outcome Scale score at discharge, Barthel index score at 6 months, and postoperative complication rates for rebleeding and pneumonia. RESULTS: There were no significant differences in basic characteristics between the 2 groups (P > 0.05). The hematoma clearance rate was significantly lower in the navigation group (49.18 ± 16.76%) than in the traditional group (84.29 ± 6.91%, P < 0.01). The duration of surgery and duration of hospitalization were significantly shorter in the navigation group (55.00 ± 11.89 minutes and 24.25 ± 7.1 days, respectively) than in the traditional group (156.38 ± 47.9 minutes and 32.63 ± 9.8 days, respectively; both P < 0.01). There were also significant differences between the 2 groups in Glasgow Outcome Scale scores (P = 0.006). The Barthel index scores were significantly greater in the navigation group (73.13 ± 18.76) than in the traditional group (57.63 ± 26.63, P < 0.05). There were no significant differences between the 2 groups in the complication rates (P > 0.05). CONCLUSIONS: Under certain conditions, compared with standard craniotomy and hematoma evacuation, navigation-guided hematoma puncture aspiration and catheter drainage is simple, effective, and safe as a treatment for hypertensive basal ganglia hemorrhage.

Two occurrences of delayed epidural hematoma in different areas following decompressive craniectomy for acute subdural hematoma in a single patient: a case report.

BACKGROUND: Delayed epidural hematoma (DEH) following evacuation of traumatic acute subdural hematoma (ASDH) or acute epidural hematoma (EDH) is a rare but devastating complication, especially when it occurs sequentially in a single patient. CASE PRESENTATION: A 19-year-old man who developed contralateral DEH following craniotomy for evacuation of a traumatic right-side ASDH and then developed a left-side DEH of the posterior cranial fossa after craniotomy for evacuation of the contralateral DEH. He was immediately returned to the operating room for additional surgeries and his neurological outcome was satisfactory. CONCLUSIONS: Although DEH occurring after evacuation of ASDH or acute EDH is a rare event, timely recognition is critical to prognosis.

Detection of specific Chlamydia pneumoniae and cytomegalovirus antigens in human carotid atherosclerotic plaque in a Chinese population.

To explore the relationship between certain pathogens, such as chlamydia pneumonia (Cpn) and cytomegalovirus (CMV), and carotid atherosclerosis (AS) in a Chinese population.Twenty-five carotid atherosclerotic stenosis patients from the Beijing Tiantan Hospital (affiliated with Capital Medical University) participated in the study. After undergoing digital subtraction angiography (DSA) and/or computed tomography angiography (CTA), the degree of carotid artery stenosis was over 70% in all cases, and the patients underwent carotid endarterectomy. Plaque specimens were obtained during surgery. The streptavidin-peroxidase (SP) method was used to test the Cpn and CMV antigens in the specimens, and the relationship between the Cpn and CMV pathogen infections and AS was analyzed based on the test results. In the group of 25 carotid atherosclerotic specimens, the detection rate of the Cpn-specific antigens was 84.0% (21/25). In the control group, the detection rate was 13.3% (2/15) in the ascending aortic intima. Thus, the between-group difference was significant (P<0.01). The CMV-specific antigen detection rate was 72.0% (18/25) using the same experimental group specimens, and the detection rate was zero in the control group. Thus, there were significant between-group differences (P<0.01). Due to the high detection rate of Cpn- and CMV-specific antigens in carotid atherosclerotic plaque in a Chinese population, it can be inferred that pathogens such as Cpn and CMV are one factor associated with carotid atherosclerosis.

Long non-coding RNA in glioma: signaling pathways.

Glioma is regarded as the most prevalent malignant carcinoma of the central nervous system. Thus, the development of new therapeutic strategies targeting glioma is of significant clinical importance. Long non-coding RNAs (lncRNAs) are functional RNA molecules without a protein-coding function and are reportedly involved in the initiation and progression of glioma. Dysregulation of lncRNAs in glioma is due to activation of several signaling pathways, such as the BRD4-HOTAIR-ß-catenin/PDCD4, p53-Hif-H19/IGF2 and CRNDE/mTOR pathways. Furthermore, microRNAs (miRNAs) such as miR-675 also interact with lncRNAs in glioma. Thus, exploring the mechanisms by which lncRNA control processes will be instrumental for devising new effective therapies against glioma.

Management of screwdriver-induced penetrating brain injury: a case report.

BACKGROUND: Penetrating brain injury (PBI) can be caused by several objects ranging from knives to chopsticks. However, an assault with long and electric screwdriver is a peculiar accident and is relatively rare. Because of its rarity, the treatments of such injury are complex and nonstandardized. CASE PRESENTATION: We presented a case of a 54-year-old female who was stabbed with a screwdriver in her head and accompanied by loss of consciousness for 1 h. Computer tomography (CT) demonstrated that the screwdriver passed through the right zygomatic bone to posterior cranial fossa. Early foreign body removal and hematoma evacuation were performed and the patient had a good postoperative recovery. CONCLUSIONS: In this study, we discussed the clinical presentation and successful management of such a unique injury caused by a screwdriver. Our goal is to demonstrate certain general management principles which can improve patient outcomes.

Review: Traumatic brain injury and hyperglycemia, a potentially modifiable risk factor.

Hyperglycemia after severe traumatic brain injury (TBI) occurs frequently and is associated with poor clinical outcome and increased mortality. In this review, we highlight the mechanisms that lead to hyperglycemia and discuss how they may contribute to poor outcomes in patients with severe TBI. Moreover, we systematically review the proper management of hyperglycemia after TBI, covering topics such as nutritional support, glucose control, moderated hypothermia, naloxone, and mannitol treatment. However, to date, an optimal and safe glycemic target range has not been determined, and may not be safe to implement among TBI patients. Therefore, there is a mandate to explore a reasonable glycemic target range that can facilitate recovery after severe TBI.

Regulation of the HMOX1 gene by the transcription factor AP-2δ with unique DNA binding site.

AP-2 transcription factors are important sequence-specific DNA-binding regulators that are expressed in the neural crest and other tissues during mammalian development. The human AP-2 family of transcription factors consists of five members, AP-2α, -ß, -γ, -δ and -ε, which have an important role in the regulation of gene expression during development and in the differentiation of multiple organs and tissues. The present study aimed to investigate the mechanism by which AP-2δ mediates heme oxygenase-1 (HMOX1) gene expression. It was identified that the human AP-2δ protein exhibited weak binding to a suboptimal AP-2 sequence, 5'-GCCN3GGC-3', to which all other AP-2 proteins bind in vitro, providing the first example of DNA target specificity amongst the AP-2 family. AP-2δ protein bound to an optimized AP-2 consensus DNA sequence, 5'-GCCTGAGGC-3', in vitro and transactivated gene expression in eukaryotic cells. The transactivation domain of Ap-2δ differs notably from those in the other AP-2 proteins as it lacks the PY motif (XPPXY) and several other conserved residues that are important for the transcriptional activity of AP-2 proteins, yet it functions as an equally strong activator.

Cloning, expression and biochemical characterization of a novel, moderately thermostable GDSL family esterase from Geobacillus thermodenitrificans T2.

A thermostable GDSL family esterase-encoding gene, EstL5, was directly obtained from the genomic DNA of Geobacillus thermodenitrificans T2. Recombinant hexahistidine-tagged EstL5 was overexpressed, purified, and its biochemical properties were partially characterized. EstL5 was observed to be active within the temperature range of 0-80°C, having maximal activity at 60°C. Unlike most other thermostable enzymes, EstL5 displayed 24% of its highest activity at 0°C. EstL5 exhibited a high level of activity within a pH range of 6.0-11.0, showing the highest activity at pH 8.0. EstL5 also retained 100% of its activity after a 12-h incubation at 55°C. Furthermore, this enzyme was observed to be strongly inhibited by 10% (w/v) SDS and 0.1 mM PMSF.

The association of ACT -17 A/T polymorphism with Alzheimer's disease: a meta-analysis.

Association studies between Alpha-1-antichymotrypsin (ACT)-17(A > T) polymorphisms and Alzheimer's disease (AD) susceptibility have shown conflicting results. In this investigation, we performed a meta-analysis to assess the purported associations. Subgroup analyses based on ethnicity (Caucasians, East-Asian and American mixed) were also performed including a total of 5,676 AD patients and 5,460 controls for ACT-17. Overall, allele contrast (A vs. T) of ACT -17 polymorphism produced significant results in the worldwide population [P(heterogeneity)=0.01, random-effects (RE) odds ratio (OR) 1.12; 95% CI 1.04-1.21, P=0.003] and in the Caucasian population [P(heterogeneity)=0.03, RE OR1.11 95% CI 1.01-1.24, P=0.04]. Meta-analyses of other genetic contrasts suggested that the A allele carriers are associated with increased susceptibility to AD in variant populations. No significant association was observed in the East-Asian subgroup analysis. In conclusion, ACT-17 variation presents a risk factor for AD in the worldwide population, especially in the Caucasian population.

Crystal structure of Human ASB9-2 and substrate-recognition of CKB.

Human ankyrin repeat and suppressor of cytokine signaling box protein 9 (hASB9) is a specific substrate-recognition subunit of an elongin C-cullin-SOCS box E3 ubiquitin ligase complex. It recognizes its substrate, brain type creatine kinase (CKB), using the ankyrin repeat domain; and facilitates the polyubiquitination of CKB to mediate proteasomal degradation through the SOCS box domain. HASB9-2 is an isoform of hASB9 that contains one ankyrin repeat domain. In this study, the crystal structure of hASB9-2 is shown at 2.2-Å resolution using molecular replacement. Overall, hASB9-2 forms a slightly curved arch with a characteristic L-shaped cross-section. Amino acid substitution analysis based on docking experiments revealed that His103 and Phe107 in hASB9-2 are essential for binding to CKB. Analysis of truncation mutants demonstrated that the first six ankyrin repeats along with the N-terminal region of hASB9-2 contribute to the interaction with CKB.

A global genomic view on LNX siRNA-mediated cell cycle arrest.

LNX protein is the first described PDZ domain-containing member of the RING finger-type E3 ubiquitin ligase family. Studies have approved that LNX could participate in signal transduction, such as Notch pathway, and play an important role in tumorigenesis. In this study, we found that down-regulation of LNX resulted in G0/G1 cell cycle arrest in G0/G1 phase in HEK293 cells. To explore the molecular mechanism of this phenomenon, we employed expression microarray to comparatively analyze the genome-wide expression between the LNX-knockdown cells and the normal cells. We also used quantitative real-time PCR to further confirm the differential expression patterns of 25 transcripts involved in cell cycle. Combined with known information about genic functions, signal pathways and cell cycle machinery, we analyzed the role of endogenous LNX in cell cycle. The results suggest that down-regulation of LNX could result in cell cycle arrest in G0/G1 phase through inhibition of ß-catenin, MAPK, NFκB, c-Myc-dependent pathway and activation of p53, TGF-ß-dependent pathway. This study provides new perspectives on LNX's pleiotropic activities, especially its essential role in cell proliferation and cell cycle.

Selection of reliable reference genes for gene expression study in nasopharyngeal carcinoma.

AIM: To construct a system for selecting reference genes (RGs) and to select the most optimal RGs for gene expression studies in nasopharyngeal carcinoma (NPC). METHODS: The total RNAs from 20 NPC samples were each labeled with Cy5-dUTP. To create a common control, the total RNA from 15 nasopharyngeal phlogistic (NP) tissues was mixed and labeled via reverse transcription with Cy3-dUTP. cDNA microarrays containing 14 112 genes were then performed. A mathematical approach was constructed to screen stably expressed genes from the microarray data. Using this method, three genes (YARS, EIF3S7, and PFDN1) were selected as candidate RGs. Furthermore, 7 commonly used RGs (HPRT1, GAPDH, TBP, ACTB, B2M, G6PDH, and HBB) were selected as additional potential RGs. Real-time PCR was used to detect these 10 candidate genes' expression levels and the geNorm program was used to find the optimal RGs for NPC studies. RESULTS: On the basis of the 10 candidate genes' expression stability level, geNorm analysis identified the optimal single RG (YARS or HPRT1) and the most suitable set of RGs (HPRT1, YARS, and EIF3S7) for NPC gene expression studies. In addition, this analysis determined that B2M, G6PDH, and HBB were not appropriate for use as RGs. Interestingly, ACTB was the least stable RG in our study, even though previous studies had indicated that it was one of the most stable RGs. Three novel candidate genes (YARS, EIF3S7, and PFDN1), which were selected from microarray data, were all identified as suitable RGs for NPC research. A RG-selecting system was then constructed, which combines microarray data analysis, a literature screen, real-time PCR, and bioinformatic analysis. CONCLUSION: We construct a RG-selecting system that helps find the optimal RGs. This process, applied to NPC research, determined the single RG (YARS or HPRT1) and the set of RGs (HPRT1, YARS, and EIF3S7) that are the most suitable internal controls.