Combined transcriptome and proteome analysis revealed the molecular regulation mechanisms of zinc homeostasis and antioxidant machinery in tobacco in response to different zinc supplies.

Zinc (Zn) is an essential micronutrient for plants. Adequate regulation of Zn uptake, transport and distribution, and adaptation to Zn-deficiency stress or Zn-excess toxicity are crucial for plant growth and development. However, little has been done to understand the molecular responses of plants toward different Zn supply levels. In the present study, we investigated the growth and physiological responses of tobacco seedlings grown under Zn-completely deficient, Zn-limiting, Zn-normal, and Zn-4-fold sufficient conditions, respectively, and demonstrated that Zn deficiency/limitation caused oxidative stress and impaired growth of tobacco plants. Combined transcriptome and proteome analysis revealed up-regulation of genes/proteins associated with Zn uptake and distribution, including ZIPs, NAS3s, and HMA1s, and up-regulation of genes/proteins involved in regulation of oxidative stress, including SODs, APX1s, GPX6, and GSTs in tobacco seedlings in response to Zn deficiency/limitation, suggesting that tobacco possessed mechanisms to regulate Zn homeostasis primarily through up-regulation of the ZIPs-NAS3s module, and to alleviate Zn deficiency/limitation-induced oxidative stress through activation of the antioxidant machinery. Our results provide novel insights into the adaptive mechanisms of tobacco in response to different Zn supplies, and would lay a theoretical foundation for development of varieties of tobacco or its relatives with high tolerance to Zn-deficiency.

Reversal of subtype-selectivity and function by the introduction of a para-benzamidyl substituent to N-cyclopropylmethyl nornepenthone.

The discovery and development of novel µ-opioid receptor (MOR) antagonists is a significant area to combat Opioid Use Disorder (OUD). In this work, a series of para-substituted N-cyclopropylmethyl-nornepenthone derivatives were designed and synthesized and pharmacologically assayed. Compound 6a was identified as a selective MOR antagonist both in vitro and in vivo. Its molecular basis was elucidated using molecular docking and MD simulations. A subpocket on the extracellular side of the TM2 domain of MOR, in particular the residue Y2.64, was proposed to be responsible for the reversal of subtype selectivity and functional reversal of this compound.

Silica Nanoparticles Promote Apoptosis in Ovarian Granulosa Cells via Autophagy Dysfunction.

Although silica nanoparticles (SNPs) are generally thought to be biocompatible and safe, the adverse effects of SNPs were also reported in previous studies. SNPs cause follicular atresia via the induction of ovarian granulosa cell apoptosis. However, the mechanisms for this phenomenon are not well understood. This study focuses on exploring the relationship between autophagy and apoptosis induced by SNPs in ovarian granulosa cells. Our results showed that 25.0 mg/kg body weight (b.w.)/intratracheal instillation of 110 nm in diameter spherical Stöber SNPs caused ovarian granulosa cell apoptosis in follicles in vivo. We also found that SNPs mainly internalized into the lumens of the lysosomes in primary cultured ovarian granulosa cells in vitro. SNPs induced cytotoxicity via a decrease in viability and an increase in apoptosis in a dose-dependent manner. SNPs increased BECLIN-1 and LC3-II levels, leading to the activation of autophagy and increased P62 level, resulting in the blockage of autophagic flux. SNPs increased the BAX/BCL-2 ratio and cleaved the caspase-3 level, resulting in the activation of the mitochondrial-mediated caspase-dependent apoptotic signaling pathway. SNPs enlarged the LysoTracker Red-positive compartments, decreased the CTSD level, and increased the acidity of lysosomes, leading to lysosomal impairment. Our results reveal that SNPs cause autophagy dysfunction via lysosomal impairment, resulting in follicular atresia via the enhancement of apoptosis in ovarian granulosa cells.

The relationship between physical activity and subjective cognitive decline: Evidence from the behavioral risk factor surveillance system (BRFSS).

BACKGROUND: Studies have shown that subjective cognitive decline (SCD) is a major risk factor for mild cognitive impairment or even dementia, but the relationship between physical activity (PA) and SCD is still unclear. The goal of current study is to address how various physical activities relate to SCD. METHODS: 216,593 adults from the Behavioral Risk Factor Surveillance System (BRFSS) were included in this study. We measured SCD and PA with participants' self-report. With the unconditional logistic regression model, the association between PA and SCD was investigated. We used a four-way decomposition method to explore the mediation roles of depression between PA and SCD. The nearest matching method of propensity score and multinomial propensity score were used to reduce the effects of confounding factors. RESULTS: Compared with those inactive, the weighted adjusted odds ratios (AORs) of SCD among those who were physically active were <1 (p < 0.005), regardless of the type of PA. The top three PA in weighted AORs were: running (AOR: 0.51, 95 % CI: 0.50-0.52), aerobics exercise (AOR: 0.55, 95 % CI: 0.53-0.56), and weightlifting (AOR: 0.60, 95 % CI: 0.59-0.62). The dose-response relationship between PA and SCD was found. Participants who engaged in PA for 241-300 min per week (AOR: 0.61, 95 % CI: 0.59-0.62) or exercised metabolic equivalent of 801-1000 per week (AOR: 0.62, 95 % CI: 0.62-0.65) had the lowest risk of SCD. CONCLUSIONS: Regardless of the specific PA types, engaging in PA is associated with a reduced risk of having SCD, and people who engage in running had the lowest risk of SCD. There was a dose-response relationship between PA and SCD, and PA-based interventions should be developed accordingly to prevent cognitive deterioration in older age.

Association of light-intensity physical activity, sedentary time and body composition in adolescents / 中国学校卫生

Objective@#To explore the association between light intensity physical activity (LPA) and sedentary behavior (SB) with body composition, so as to provide data references for improving adolescent physical health.@*Methods@#From August 2020 to January 2021, general information of 694 students in grade one of a high school in Foshan City was collected, and the 24 hour activity behavior and body composition of the students were measured objectively by triaxial accelerometer and bioelectrical impedance tester. Dual component multivariate regression and dual compositional isotemporal substitution model were used to explore the relationship between LPA and SB and body composition.@*Results@#LPA was associated with lower fat relative dominance (FRD) (male weekends FRD=-21.44%, female weekly FRD=-17.83%, weekdays FRD=-18.27%, P <0.05), and LPA was also associated with higher muscle relative dominance (MRD) and bone relative dominance (BRD) (male weekends MRD=12.78%, BRD= 12.87 %; female weekly MRD=11.64%, BRD=9.01%; female weekdays MRD=12.02%, BRD=9.23%, P <0.05). Replacing sedentary behavior (SB) with 10 minutes of LPA could reduce fat proportion [male:weekly -0.15(-0.26--0.04), weekdays -0.12 (-0.22--0.02); female:weekly -0.18(-0.27--0.08), weekdays -0.16(-0.25--0.07)) and increase muscle proportion (male:weekly 0.14(0.03-0.24), weekdays 0.11(0.02-0.21); female:weekly 0.17(0.07-0.26), weekdays 0.15(0.07-0.24)].@*Conclusion@#Interrupting continuous SB with LPA can serve as an intervention measure to promote physical health and fitness in adolescents. School should encourage students to engage in frequent LPA during breaks and after school activities, while avoiding prolonged SB.

[Comparison of the effects of removable dentures made by 3D printing and traditional casting methods on patients' subjective feelings].

PURPOSE: To compare the different effects of removable dentures made by 3D printing and traditional casting methods on patients' subjective feelings. METHODS: A total of 80 patients with dentition defects of Ken's Class Ⅰ and Subclass Ⅱ were selected from the Department of Prosthodontics. The patients were randomly divided into 2 groups, with removable dentures made by using 3D printing and plaster casting method, respectively. The patients were asked to re-visit 1 week after wearing the dentures to observe and record intraoral mucosal tenderness points. At the same time, mastication efficiency was measured by absorbance method. The patients were followed up for 2 months after wearing dentures, and questionnaires were issued to them to investigate subjective feelings and satisfaction. The subjective feelings of patients included masticatory ability, retention effect, convenience, comfort, speech function and facial appearance. Satisfaction evaluation included three aspects: treatment duration, cost and final outcome. Each aspect of evaluation used a 5-point system, with a minimum score of 1 and a maximum score of 5. The higher the score, the better the patient's subjective feelings or the higher the satisfaction. The data were statistically analyzed with SPSS 17.0 software package. RESULTS: The tender points in 3D printing group was less than the plaster casting group, while the chewing efficiency of 3D printing group was higher than the plaster casting group, the difference was statistically significant (P＜0.05). The difference of subjective feeling and satisfaction was also significant between the two groups(P＜0.05). CONCLUSIONS: 3D printing to make removable denture has certain advantages in improving the accuracy of removable denture and the comfort of patients.

SLL-627 Is a Highly Selective and Potent κ Opioid Receptor (KOR) Agonist with an Unexpected Nonreduction in Locomotor Activity.

Undue central nervous system (CNS) side effects including dysphoria and sedation remain to be a challenge for the development of κ opioid receptor (KOR) agonists as effective and safe analgesics. On the basis of our previous work on morphinan-based KOR agonists, a series of 7α-methyl-7ß-substituted northebaine derivatives were designed, synthesized, and biologically assayed. Among others, compound 4a (SLL-627) has been identified as a highly selective and potent KOR agonist both in vitro and in vivo, and its molecular basis was also examined and discussed. Besides low liability to conditioned place aversion (CPA) test, treatment of SLL-627 was associated with a nonreduction in locomotor activity, compared to most of the other arylacetamide- or morphinan-based KOR agonists which generally exhibited apparently sedative effects. This unexpected finding provides new insights to dissociate analgesia from sedation for future discovery of innovative KOR agonists.

De novo transcriptome analysis reveals the molecular regulatory mechanism underlying the response to excess nitrogen in Azolla spp.

Phytoremediation potential of Azolla in removal of nitrogen from wastewater has been promising. However, little is known about the response of Azolla to high concentrations of nitrogen. In this study, the responses of four Azolla species to different concentrations of total nitrogen ranging from 0 to 180 mg L-1 were examined. The responses varied among different species, and the high nitrogen-tolerant species A. caroliniana and A. microphylla could remove nitrogen from aqueous solutions with higher efficiencies. We further performed transcriptome analysis to explore the molecular mechanism underlying the response to high nitrogen stress in Azolla. RNA-seq analysis revealed a synergistic regulatory network of differentially expressed genes (DEGs) involved in nitrogen transport and metabolism in A. microphylla, mainly in the roots. Under high nitrogen treatment, the DEGs encoding nitrate transporters or nitrate transporter 1/peptide transporters (NRTs/NPFs), ammonium transporters (AMTs), nitrate reductase (NIA), nitrite reductase (NIR) and glutamine synthetases/glutamate synthases (GSs/GOGATs) were down-regulated, and the DEGs encoding glutamate dehydrogenases (GDHs) were up-regulated, suggesting that A. microphylla possessed high tolerance against excess nitrogen through down-regulation of nitrate and ammonium uptake and fine regulation of nitrogen assimilation in the roots. Our results provided a theoretical foundation for better utilization of Azolla for wastewater treatment.

Relationship between physical activity and mental health in a national representative cross-section study: Its variations according to obesity and comorbidity.

BACKGROUND: Physical activity is positively associated with mental health in obese people with chronic comorbidities. However, how physical activity types (PATs), physical activity frequency (PAF), and physical activity duration (PAD) are associated with mental health need to be further clarified. The current study investigated and compared the effectiveness of PATs, physical activity frequency PAF and PAD for mental health in obese people with various chronic comorbid conditions. METHODS: This cross-sectional study included 871,919 adults who participated in the Behavioral Risk Factor Surveillance System (BRFSS). They were divided into four groups: healthy people, obese people with 0, 1, and 2+ chronic comorbid conditions. The zero-inflated negative binomial (ZINB) regression model and the generalized additive model were used to explore the association between physical activity and mental health burden in the four groups, respectively. RESULTS: Jogging (30.00%), hiking (28.36%) and bicycling (28.32%) have greater improvement in mental health of healthy people; jogging (19.25%), golf (19.95%) and bicycling machine exercise (19.13%) showed a greater improvement in mental health of obese people with no chronic comorbid condition; and aerobic exercise videos or class showed a greater improvement in mental health of obese people with one chronic comorbid condition (22.14%) and obese people with two or more chronic comorbid conditions (19.60%). Non-linear relationships were observed between PAF, PAD, and energy expenditure and mental health. The healthy participants who exercised about 10-15 times a month and 40-50 min per session or about 400-600 METs-min per week had greater benefits for mental health. However, the lowest point of the smooth curve moved to the left with an increasing number of chronic comorbid conditions in obese people. CONCLUSIONS: Almost all PATs were associated with better mental health, but their benefits decreased with increasing number of chronic comorbid conditions in obese people. There were U-shaped relationships between mental health and weekly physical activity frequency, duration, and METs-min.

Activation of Autophagy by Low-Dose Silica Nanoparticles Enhances Testosterone Secretion in Leydig Cells.

Silica nanoparticles (SNPs) can cause abnormal spermatogenesis in male reproductive toxicity. However, the toxicity and toxicological mechanisms of SNPs in testosterone synthesis and secretion in Leydig cells are not well known. Therefore, this study aimed to determine the effect and molecular mechanism of low doses of SNPs in testosterone production in Leydig cells. For this, mouse primary Leydig cells (PLCs) were exposed to 100 nm Stöber nonporous spherical SNPs. We observed significant accumulation of SNPs in the cytoplasm of PLCs via transmission electron microscopy (TEM). CCK-8 and flow cytometry assays confirmed that low doses (50 and 100 µg/mL) of SNPs had no significant effect on cell viability and apoptosis, whereas high doses (more than 200 µg/mL) decreased cell viability and increased cell apoptosis in PLCs. Monodansylcadaverine (MDC) staining showed that SNPs caused the significant accumulation of autophagosomes in the cytoplasm of PLCs. SNPs activated autophagy by upregulating microtubule-associated protein light chain 3 (LC3-II) and BCL-2-interacting protein (BECLIN-1) levels, in addition to downregulating sequestosome 1 (SQSTM1/P62) level at low doses. In addition, low doses of SNPs enhanced testosterone secretion and increased steroidogenic acute regulatory protein (StAR) expression. SNPs combined with rapamycin (RAP), an autophagy activator, enhanced testosterone production and increased StAR expression, whereas SNPs combined with 3-methyladenine (3-MA) and chloroquine (CQ), autophagy inhibitors, had an opposite effect. Furthermore, BECLIN-1 depletion inhibited testosterone production and StAR expression. Altogether, our results demonstrate that low doses of SNPs enhanced testosterone secretion via the activation of autophagy in PLCs.

Dezocine as a potent analgesic: overview of its pharmacological characterization.

Dezocine, a synthetic opioid, introduced in 1970s as an analgesic, was redeveloped for relieving moderate to severe pain by Yangtze River Pharmaceutical Group in China in 2009. To date, dezocine occupies 45% of China's opioid analgesic market. Along with dezocine being a dominated painkiller, a certain amount of research was conducted to elucidate dezocine's action. In this review we summarize the current knowledge on the receptor, preclinical and clinical pharmacology of dezocine. Briefly, preclinical data show that dezocine is effective under varying pain conditions, particularly chronic neuropathic pain and cancer pain, through activation of opioid receptors, and inhibition of norepinephrine reuptake. Clinical data establish the effectiveness of dezocine either as a primary analgesic for postoperative pain management or a supplement for balanced analgesia. The receptor profile of dezocine is different from known pure µ agonists, and allows it to be used in combination with other opioids for additivity in efficacy or lower incidence of adverse effects.

Discovery of an M-Substituted N-Cyclopropylmethyl-7α-phenyl-6,14-endoethanotetrahydronorthebaine as a Selective, Potent, and Orally Active κ-Opioid Receptor Agonist with an Improved Central Nervous System Safety Profile.

The search for selective kappa opioid receptor (κOR) agonists with an improved safety profile is an area of interest in opioid research. In this work, a series of m-substituted analogs were designed, synthesized, and assayed, resulting in the identification of compound 6c (SLL-1206) as a κOR agonist with single-digit nanomolar activities. The subtype selectivity of compound 6c appeared to be a consequence of an enormous decrease in the affinity for µOR and δOR, rather than a significant increase in the affinity for κOR, which was not the case for SLL-039, another selective and potent κOR agonist identified in our previous work. Besides reduced central nervous system effects, SLL-1206 exhibited substantially improved physicochemical and pharmacokinetic properties compared with SLL-039, with increases of over 20-fold in aqueous solubility and approximately 40-fold in oral bioavailability in rats.

[An evaluation of fiber reinforced composites veneer in anterior esthetic restoration].

PURPOSE: To explore the advantages of fiber reinforced composites veneer in repairing discolorated and defective anterior teeth. METHODS: Twenty porcelain veneers and 20 fiber reinforced composites veneers specimens of 2 cm long, 2 cm wide and 1 mm in thickness, with a longitudinal cross section of 45° incline were made. Another 40 fiber reinforced composites specimens of the same shape were used for comparison. After polishing and acid treatment of all the specimens according to clinical routine, resin cement was used for bonding the porcelain cover with resin veneers slope, and the conjunct specimens were soaked in 40 ℃ warm water for 24 h and drying; then the two groups of specimens were put were put on the pressure testing platform of the universal testing machine, with 1 mm/min testing pressure, and 1 cm2 square head was contacted on the surface of the bonding interface. Computer was used to record the fracture process of the two groups of specimens and the maximum compressive strength of bonding interface automatically. The compressive strength of the bonding interface under the same conditions was evaluated. SPSS 12.0 software package was used for statistical analysis. RESULTS: The compressive strength of the bonding interface between fiber reinforced composites was significantly higher than that between porcelain and fiber reinforced composites(P<0.05). CONCLUSIONS: Compared with porcelain veneers that can not be repaired when damaged in the anterior teeth, high-strength fiber resin veneers can partially be repaired with the same material, which has obvious advantages.

Uhrf1 regulates H3K9me2 modification of mTOR to inhibit the effect of autophagy in myocardial ischemia-reperfusion injury.

The regulation of mTOR and the dimethylation of histone H3 on lysine 9 (H3K9me2) H3K9me2 by Uhrf1 and the mechanism of autophagy regulation in myocardial ischemia-reperfusion injury (MIRI) were studied in vivo and in vitro. An in vitro I/R injury model was established using the primary mouse cardiomyocytes treated with H2O2. Subsequent analysis by qRT-PCR, western blot, and immunofluorescence indicated that overexpression of Uhrf1 significantly inhibited apoptosis of the H2O2-treated cardiomyocytes, reduced expression of apoptosis factors caspase-3 and Bax, and increased expression of apoptosis inhibitory factor Bcl-2. Furthermore, Uhrf1 was found to increase cardiomyocyte proliferation and promote the expression of mTOR, while the four expression peaks of H3K9me2 on the mTOR gene were inhibited by overexpression of Uhrf1. The expression of autophagy factors LC3, Beclin-1, and p-mTOR in Uhrf1-overexpressed cardiomyocytes was dramatically increased, and P62 expression was dramatically decreased. When an H3K9me2 inhibitor was added to the Uhrf1-knockdown cardiomyocytes, the expression of mTOR was increased, the expression of LC3, Beclin-1, and p-mTOR was decreased, and P62 expression was significantly increased. In the present study, Uhrf1 exhibits a protective function in MIRI, reducing the apoptosis of cardiomyocytes while increasing their proliferation and viability.

Exploration of the SAR Connection between Morphinan- and Arylacetamide-Based κ Opioid Receptor (κOR) Agonists Using the Strategy of Bridging.

κ opioid receptor (κOR) is a subtype of opioid receptors, and there are two major κOR agonists currently available, morphinans and arylacetamides, which are structurally distinct from each other. Numerous efforts had been made to correlate these series of compounds in order to establish a consensus binding pattern for κOR agonists. Unfortunately, no morphinan-based agent with an arylacetamidyl substituent has been identified as a κOR agonist with a pharmacological profile similar to arylacetamides. Since the recently described morphinan-based compound SLL-039 was identified as a selective and potent κOR agonist that contains a unique benzamidyl substituent in structure similar to arylacetamides, numerous arylacetamidyl substituents were introduced to this scaffold to examine whether the structure-activity relationships (SARs) of arylacetamides in conferring κOR agonistic activities could be reproduced by these analogues. Thus, a series of N-cyclopropylmethyl-7α-arylacetamidylphenyl-6,14-endoethanotetrahydronorthebaine analogues were designed, synthesized, and assayed for biological activities. Among these compounds, compound 4j with a 3',4'-dimethylphenylacetamidyl substituent showed a single digit low nanomolar affinity to the κOR and relatively high subtype selectivity in binding assays, but this profile was not reproduced in functional assays. In contrast, compound 4i displayed moderately selective κOR agonistic activities in functional assays, which was inconsistent with its nonselective nature in binding assays. Overall, introduction of an arylacetamidyl substituent to the morphinan-based scaffold was associated with pharmacological diversity in both binding and functional activities on opioid receptors in vitro. The resultant SARs were inconsistent with that of classical arylacetamides as κOR agonists, despite bearing a similar arylacetamidyl substituent in the structure. Therefore, the arylacetamidyl substituent of the morphinan-based scaffold was found to be disconnected from that of arylacetamides in conferring κOR activities.

Association of cancer screening and residing in a coal-polluted East Asian region with overall survival of lung cancer patients: a retrospective cohort study.

Lung cancer is the leading cause of cancer death worldwide. The Xuanwei-Fuyuan (XF) region of Yunnan, China has a high incidence of lung cancer from coal-related pollution. Effort to raise public awareness screening for lung cancer has been ongoing. We retrospectively analyzed overall survival (OS) of lung cancer patients of a tertiary cancer center in Yunnan to investigate screening and regional residential status as predictive factors. Consecutive cases of newly diagnosed lung cancer were reviewed. The lung cancer cases diagnosed by screening were more likely to be early-staged and treated by surgery than those diagnosed not by screening. In patients diagnosed not by screening, XF residential status was a significant predictor of improved OS. Frailty model detected significant heterogeneity associated with region of residence in unscreened patients. Potential biases associated with screening were examined by Monte Carlo simulations and sensitivity analyses. Focused effort in cancer screening and increased public awareness of pollution-related lung cancer in XF might have led to early diagnosis and improved OS, and increased investment in health care resources in high risk areas may have produced additional unobserved factors that underlay the association of XF residential status with improved OS in patients diagnosed not by screening.

Discovery of a Highly Selective and Potent κ Opioid Receptor Agonist from N-Cyclopropylmethyl-7α-phenyl-6,14-endoethanotetrahydronorthebaines with Reduced Central Nervous System (CNS) Side Effects Navigated by the Message-Address Concept.

Effective and safe analgesics represent an unmet medical need for the treatment of acute and chronic pain. A series of N-cyclopropylmethyl-7α-phenyl-6,14-endoethanotetrahydronorthebaines were designed, synthesized, and assayed, leading to the discovery of a benzylamine derivative (compound 4, SLL-039) as a highly selective and potent κ opioid agonist (κ, Ki = 0.47 nM, κ/µ = 682, κ/δ = 283), which was confirmed by functional assays in vitro and antinociceptive assays in vivo. The in vivo effect could be blocked by pretreatment with the selective κ antagonist nor-BNI. Moreover, this compound did not induce sedation, a common dose limiting effect of κ opioid receptor agonists, at its analgesic dose compared to U50,488H. The dissociation of sedation/antinociception found in SLL-039 was assumed to be correlated with the occupation of its benzamide motif in a unique subsite involving V1182.63, W124EL1, and E209EL2.

[Changes of abutment alveolar height after Stern ERA attachment restoration].

PURPOSE: To observe the alveolar height changes of the distal abutments in Kennedy II dentition defect restored with Stern ERA attachment. METHODS: Twenty-one Kennedy II dentition defect patients restored with Stern ERA attachment were observed at the day of restoration and 1 month, 3 months and 6 months after restoration. Digital panoramic radiographs were taken to measure the vertical distances from the distal and the mesial alveolar bone crest to the apical point in the distal abutments and were used to observe and compare the alveolar height changes of the distal abutments.The data was analyzed with SPSS16.0 software package for Student's t test. RESULTS: The distal and medial alveolar height of the distal abutments was not significantly reduced (P>0.05) 1 month, 3 months and 6 months after restoration with Stern ERA attachment. CONCLUSIONS: According to the digital panoramic radiograph, the alveolar height of the distal abutments in Kennedy II dentition defect restored with Stern ERA attachment was not significantly changed in 6 months after restoration. It may benefit for the the health and stability of the distal abutments by using Stern ERA attachment in Kennedy II dentition defect.

[Cytotoxicity of three kinds of temporary crown and bridge materials on mouse fibroblasts in vitro].

PURPOSE: This study was to investigate the cytotoxicity in vitro of three kinds of common temporary crown and bridge materials, i.e.,self-curing resin, heat-curing resin, and DMG-TEMP bi-acrylic composite. METHODS: L-929 mouse fibroblasts were used to evaluate the cytotoxicity of three kinds of temporary crown and bridge materials by agar overlay assay to test the cell death rate through trypan blue dyeing. RESULTS: The agar overlay assay showed that the value of Zone/Lysis of self-curing resin was 2/3, heat-curing resin was 1/0, and DMG-TEMP bi-acrylic composite was 1/2. Self-curing resin caused the most significant cytotoxicity (P<0.05), followed by heat-curing resin and DMG-TEMP composite, and the latter two showed no significant difference(P>0.05). The results of trypan blue dyeing were in accordance with the above. CONCLUSIONS: Self-curing resin, heat-curing resin, and DMG-TEMP bi-acrylic composite could decrease L-929 fibroblasts proliferation. Of all, self-curing resin caused most marked cytotoxicity, so we should avoid using self-curing resin as temporary crown and bridge to protect pulp.