BACKGROUND:Clinical studies suggest that both bone quality and excessive crown-to-implant ratio are factors that affect the success rate of implant surgery,but there is no consensus on how large the crown-to-implant ratio under each bone quality will affect the prognosis of implant repair.OBJECTIVE:To analyze the stress and strain of bone tissue around implant restorations with different crown-to-implant ratios under different bone types after stress loading using three-dimensional finite element method.Combined with the Frost bone mechanics regulation system theory,the physiological limits of bone strain were observed for each bone type within a certain range of crown to implant ratios.METHODS:Cone beam CT data were selected from a patient to establish solid bone block models with four different bone types(class Ⅰ bone:cortical bone thickness 3 mm+dense cancellous bone,class Ⅱ bone:cortical bone thickness 2 mm+relatively dense cancellous bone,class Ⅲ bone:cortical bone thickness 1 mm+relatively low-density cancellous bone,class Ⅳ bone:cortical bone thickness 1 mm+low-density cancellous bone).Implant restorations with five different crown-to-implant ratios(1,1.5,2,2.5,and 3)were created on each bone block model,for a total of 20 models.Vertical and oblique forces were applied to the dental crown to observe the von Mises stress values,strains,and displacement of the cortical and cancellous bones,as well as the degree of implant displacement.RESULTS AND CONCLUSION:(1)In the class Ⅰ bone model,when the crown-to-implant ratio reached 3 under oblique loading,the cortical bone strain exceeded the physiological limit.In the class Ⅱ bone model,under oblique loading,when the crown-to-implant ratio reached 2.5,the cortical bone strain exceeded the physiological limit.In the class Ⅲ bone model,under oblique loading,cortical bone exceeded the physiological limit when the crown-to-implant ratio reached 2.5,while cancellous bone reached the critical physiological limit at 1.In the class Ⅳ bone model,under oblique loading,when the crown-to-implant ratio reached 1.5,2,2.5,and 3,the cortical bone strain exceeded the physiological limit.In the class Ⅳ bone model,all five crown-to-implant ratios of cancellous bone exceeded physiological limits.(2)Under vertical load,the cancellous bone strain exceeded the physiological limit when the crown-root ratio reached 1,2,2.5,and 3 in the class Ⅲ bone model,and when the cancellous bone strain of the five crown-root ratios in the class Ⅳ bone model exceeded the physiological limit.(3)Under oblique or vertical load,the implant displacement of the 20 groups of models did not exceed 100 μm.(4)From the perspective of biomechanics,when patients with insufficient bone height choose implant restoration,the crown-root ratio that class Ⅰ bone can tolerate is up to 2.5 times,the crown-root ratio that class Ⅱ bone can tolerate is up to 2 times,and the crown-root ratio that class Ⅲ and class Ⅳ bones can tolerate is up to 1 times due to excessive strain of cancellous bone;but the crown-root ratio that cortical bone in class Ⅲ bone can tolerate is up to 2 times.Whether class Ⅲ bone can tolerate implant restoration with a high crown-root ratio and whether cancellous bone can tolerate higher strains needs further study.

BACKGROUND:Clinical studies suggest that both bone quality and excessive crown-to-implant ratio are factors that affect the success rate of implant surgery,but there is no consensus on how large the crown-to-implant ratio under each bone quality will affect the prognosis of implant repair.OBJECTIVE:To analyze the stress and strain of bone tissue around implant restorations with different crown-to-implant ratios under different bone types after stress loading using three-dimensional finite element method.Combined with the Frost bone mechanics regulation system theory,the physiological limits of bone strain were observed for each bone type within a certain range of crown to implant ratios.METHODS:Cone beam CT data were selected from a patient to establish solid bone block models with four different bone types(class Ⅰ bone:cortical bone thickness 3 mm+dense cancellous bone,class Ⅱ bone:cortical bone thickness 2 mm+relatively dense cancellous bone,class Ⅲ bone:cortical bone thickness 1 mm+relatively low-density cancellous bone,class Ⅳ bone:cortical bone thickness 1 mm+low-density cancellous bone).Implant restorations with five different crown-to-implant ratios(1,1.5,2,2.5,and 3)were created on each bone block model,for a total of 20 models.Vertical and oblique forces were applied to the dental crown to observe the von Mises stress values,strains,and displacement of the cortical and cancellous bones,as well as the degree of implant displacement.RESULTS AND CONCLUSION:(1)In the class Ⅰ bone model,when the crown-to-implant ratio reached 3 under oblique loading,the cortical bone strain exceeded the physiological limit.In the class Ⅱ bone model,under oblique loading,when the crown-to-implant ratio reached 2.5,the cortical bone strain exceeded the physiological limit.In the class Ⅲ bone model,under oblique loading,cortical bone exceeded the physiological limit when the crown-to-implant ratio reached 2.5,while cancellous bone reached the critical physiological limit at 1.In the class Ⅳ bone model,under oblique loading,when the crown-to-implant ratio reached 1.5,2,2.5,and 3,the cortical bone strain exceeded the physiological limit.In the class Ⅳ bone model,all five crown-to-implant ratios of cancellous bone exceeded physiological limits.(2)Under vertical load,the cancellous bone strain exceeded the physiological limit when the crown-root ratio reached 1,2,2.5,and 3 in the class Ⅲ bone model,and when the cancellous bone strain of the five crown-root ratios in the class Ⅳ bone model exceeded the physiological limit.(3)Under oblique or vertical load,the implant displacement of the 20 groups of models did not exceed 100 μm.(4)From the perspective of biomechanics,when patients with insufficient bone height choose implant restoration,the crown-root ratio that class Ⅰ bone can tolerate is up to 2.5 times,the crown-root ratio that class Ⅱ bone can tolerate is up to 2 times,and the crown-root ratio that class Ⅲ and class Ⅳ bones can tolerate is up to 1 times due to excessive strain of cancellous bone;but the crown-root ratio that cortical bone in class Ⅲ bone can tolerate is up to 2 times.Whether class Ⅲ bone can tolerate implant restoration with a high crown-root ratio and whether cancellous bone can tolerate higher strains needs further study.

Objective:To analyze the clinical efficacy and learning curve for robot-assisted cortical bone trajectory (CBT) screw fixation performed by surgeons with different seniority in the treatment of lumbar degenerative disease.Methods:The clinical data of 91 lumbar degenerative disease patients underwent robot-assisted CBT screw fixation from August 2020 to December 2022 in Beijing Shijitan Hospital, Capital Medical University were retrospectively analyzed. Among them, 48 patients underwent surgery performed by the same senior surgeon (senior group), with a total of 234 CBT screws were placed; while 43 patients underwent surgery performed by the same junior surgeon (junior group), with a total of 206 CBT screws were placed. The surgical related indexes, functional improvement score, lower back pain and lower limb radiation pain scores, acceptable nail insertion rate, non invasion rate of facet joints and incidence of postoperative complications were compared between two groups. The functional improvement score was evaluated using the Japanese Orthopaedic Association (JOA) score, the pain score was evaluated using visual analog score (VAS). The cumulative sum (CUSUM) method was used to depict the learning curve with "single screw placement time" as the observation index.Results:There were no statistical difference in incision length, operation time, intraoperative blood loss and postoperative hospital stay between two groups ( P>0.05). The least squares means of JOA scores 1, 3 and 6 months after surgery in both groups increased significantly compared to baseline, while the least squares means of lower back pain VAS and lower limb radiation pain VAS decreased significantly compared to baseline; there were no statistical differences between two groups ( P>0.05). There were no statistical difference in acceptable nail insertion rate, non invasion rate of facet joints and incidence of postoperative complications between two group ( P>0.05). The CUSUM learning curves were fitting well and the inflection point for senior surgeon corresponded to 18 cases, while it was reached after performing surgery on 21 cases for junior surgeon. Conclusions:Robot-assisted CBT screw fixation performed by surgeons with different seniority could achieve similar clinical outcomes for treating lumbar degenerative disease. The senior surgeons are able to complete the initial learning stage faster than the junior surgeons, but there is not much difference in the number of surgeries performed the learning curve.

Objective To compare functional differences of CD8+T cells in lung tissues between young and aged C57BL/6J mice during the contraction phase and memory immune response phase after infection with influenza A(H1N1)virus.Methods Lung tissues from young(3-month-old)and aged(24-month-old)C57BL/6J female mice without influenza virus infection were collected to prepare single-cell suspensions,which were stimulated with phorbol 12-myristate 13-acetate(PMA)/ionomycin or cluster of differentiation(CD)3/CD28 antibodies(T-cell antigen receptor/co-stimulatory signals)respectively(non-specific antigens stimulation).Flow cytometry intracellular cytokine staining(ICS)was performed on lung CD8+T cells to detect their secretion capacity of tumor necrosis factor-α(TNF-α)and interferon-γ(IFN-γ).Young and aged C57BL/6J mice were infected intranasally with 490 PFU PR8 influenza virus,and reinfected with homologous influenza virus 28 days later.Lung tissues were isolated on day 28(the contraction phase)and day 32(the memory immune response phase)after primary infection.Influenza virus-specific MHC-Ⅰ tetramer staining was used to detect the proportion of virus-specific CD8+T cells in lung tissue CD8+T cells,and ICS was used to analyze TNF-α,IFN-γ,and granzyme B expression in CD8+CD44high T cell subset.Results After non-specific antigen stimulation,TNF-α and IFN-γ secretion capacity in lung tissue CD8+T cells of aged group mice was significantly higher than that of young group(P＜0.05).After virus-specific antigen stimulation,there were no statistically significant differences in the proportion of virus-specific CD8+T cells and the expression levels of TNF-α,IFN-γ,and granzyme B between the two groups of mice during the contraction phase(P＞0.05),while during the memory immune response phase,the proportion of virus-specific CD8+T cells and the expression levels of TNF-α,IFN-γ,and granzyme B in the aged group mice were significantly lower than those in the young group(P＜0.05).Conclusion CD8+T cells in aged mice maintain normal immune-related factor expression function under non-specific antigen stimulation,but show impaired immune-related factor expression function during antigen-specific memory immune response phase,suggesting that aging leads to defects in the formation or maintenance of CD8+T cell immune memory.

Objective:To investigate the clinical results of gasless endoscopic thyroidectomy via posterior chest-collarbone approach (GETPCA) compared with open neck surgery for papillary thyroid carcinoma (PTC) .Mthods:Retrospective analysis of PTC patients admitted to the Department of Thyroid and Breast Surgery of the Third Affiliated Hospital of Anhui Medical University from Jan. 2022 to Dec. 2023,and randomly divided into the open group and the lumbo-scopic group according to whether or not they had a requirement for an unmarked neck, in which the open group was n=100,and the lumbo-scopic group was n=67,with 39 male cases and 128 female cases. Clinicopathological characteristics, surgery-related indexes, postoperative complications, postoperative pain scores and postoperative cosmetic satisfaction were compared between the two groups.The t-test,Wilcoxon rank-sum test, χ2 test, consecutively corrected χ2 test, or Fisher’s exact probability method were used to compare the groups. Results:No recurrence was seen during the follow-up period,and none of the cases in the luminal group was open in the middle. The differences in age, body mass index BMI, gender, relative tumor location,preoperative TSH, T stage and N stage between the two groups were not statistically significant ( P>0.05) . The total operation time [ (121.07±39.80) min vs. (93.87±26.97) min]in the luminal group was greater than that in the open group,intraoperative bleeding was less than that in the open group, and the postoperative drainage flow[ (130.69±31.01) mL vs. (105.52±32.71) mL] was greater than that in the open group in the postoperative period of 72 h, and the difference was statistically significant ( P<0.001) .There was no statistical difference between the two groups in terms of 24-h postoperative drainage volume, number of central zone lymph node dissection, number of positive central zone lymph nodes,postoperative hospitalization days or total hospitalization cost ( P>0.05) .The number of cases of neck discomfort (3 cases vs.23 cases, P<0.001) and swallowing dysfunction (2 cases vs.20 cases, P=0.003) in the luminal group was smaller than that in the open group,and the difference was statistically significant.The difference in the incidence of bleeding,incision infection,seroma,temporary recurrent laryngeal nerve injury and temporary parathyroid gland injury between the two groups was also not statistically significant ( P>0.05) .The postoperative NRS on day 1 and postoperative NRS on day 3 of the luminal group were lower than those of the open group,and the difference was statistically significant ( P>0.05) ,while there was no statistically significant difference between the postoperative NRS on day 7,the postoperative NRS on month 1 and the postoperative NRS on month 3 ( P>0.05) .Cosmetic satisfaction at 6 months postoperatively was higher in the luminal group than in the open group,and the difference was statistically significant ( P<0.001) . Conclusion:GETPCA for the treatment of the PTC is safe and feasible,with satisfactory cosmetic results and reduction of neck discomfort and swallowing dysfunction,which is worthy of clinical popularization.

Objective To investigate the effects of Caenorhabditis elegans(C.elegans)endogenous U6 promoters on dpy-10 gene editing efficiency.Methods We screened endogenous U6 small nuclear RNA(snRNA)genes of C.elegans from the WormBase database and constructed 14 editing plasmids targeting dpy-10 by replacing the U6r07e5.16 promoter in the pSX524 plasmid(Peft-3::cas9::tbb-2 terminator::U6 r07e5.16::dpy-10 sgRNA)through molecular cloning.Gene editing was performed in wild-type C.elegans using a standardized microinjection protocol.Gene editing efficiency and the high-efficiency gene editing index were quantified based on the screening of dpy-10 mutant phenotypes in the F1 progeny.Results A total of 15 U6 snRNA genes(r07e5.16,f35c11.9,t20d3.13,k09b11.15,k09b11.16,w05b2.8,c28a5.7,f54c8.9,k09b11.11,k09b11.12,k09b11.14,t20d3.12,f54c8.8,f54c8.10,and k09b11.13)were identified from the WormBase database.Based on the editing efficiency and high-efficiency gene editing index,the activity of these promoters was evaluated,and 4 U6 promoters(w05b2.8,c28a5.7,f54c8.9,and k09b11.11)were found to have significantly enhanced gene editing success rates,outperforming other promoters,including U6r07e5.16 and U6k09b11.12,which are commonly used in the C.elegans research community.Notably,the gRNAF+E scaffold did not show superior editing efficiency over the gRNA scaffold when paired with the optimal U6w05b2.8 promoter.Conclusion In this study,U6 promoters that significantly improve gene editing efficiency in C.elegans are identified and the critical role of promoter optimization in CRISPR-Cas9 systems is highlighted.These findings provide a valuable foundation for improving genome editing strategies and offer new ideas for optimizing the CRISPR technology applied in nematode research.

Objective To optimize the real-time quantitative polymerase chain reaction(RT-qPCR)data analysis process through mathematical principles by replacing the biased 2-??CT method with a more rigorous 2-CT method,thereby improving the accuracy of gene expression quantification analysis.Methods Essentially,the CT value serves as the exponent in a base-2 exponential equation within the logic of comparative CT method.In the traditional 2-??CT method,the arithmetic means of raw CT and ΔCT values are directly calculated and the exponential nature of CT data is overlooked,which may introduce systematic bias to the calculation results.We propose a new method,entitled the 2-CT method,in which all calculations are based on the transformation of CT values into 2-CT.This includes computing the relative initial expression levels of target and reference genes within each sample,the relative abundance of the target gene,and its fold change across groups.Statistical comparisons are then performed based on fold change values.By strictly adhering to the exponential nature of of CT values,the biases introduced by arithmetic averaging at the CT or ΔCT level are avoided.We applied this method to multiple RT-qPCR datasets to evaluate the differences between the traditional 2-??CT and the proposed 2-CT methods in gene expression quantification,as well as the effect of the differences.Results In the original dataset from LIVAK and SCHMITTGEN,the two methods produced similar results.However,in the cadmium exposure experiment,findings from the 2-??CT method indicated that 8-hour cadmium exposure caused an increase of irg-6 gene expression in Caenorhabditis elegans from 1.314-fold to 7.125-fold(P=0.000 2).In contrast,findings from the 2-CT method showed a fold change from 1.0 to 4.124(P=0.001 5),a 70%difference between the two methods.Conclusion The2-CT method provides a mathematically more rigorous approach that more accurately reflects gene expression changes,particularly in experiments with high CT variability.It offers a more reliable computational paradigm for quantitative gene expression analysis.

Objective: To investigate the expression of ribosomal protein L26 ( RPL26) in gastric cancer cells (GC) and its effect on cell apoptosis and proliferation . Methods: The expression of RPL26 in GES-1 and GC cell lines was detected by Western blot. GC cell line HGC-27 was used to construct RPL26 overexpression cell line , and GC cell lines HGC-27 and AGS cells were used to construct RPL26 knockdown cell line . The overexpression and knockdown efficiency of RPL26 were detected by Western blot. Cell counting kit-8 (CCK-8) , colony formation assay and Transwell assay were used to detect the effects of the overexpression and knockdown of RPL26 on the pro- liferation and migration of GC cells . Western blot was used to detect the expression of Phosphatidylinositol-3-kinase (PI3K) / protein kinase B (AKT) signaling pathway related factors PI3K , AKT , phosphorylated phosphatidylinosi- tol-3-kinase (p-PI3K) , phosphorylated protein kinase B ( p-AKT) and downstream factors B-Cell lymphoma-2 (Bcl-2) , Bcl-2 associated X protein (Bax) and Cyclin A , G1 /S-specific Cyclin D1(Cyclin D1) , Cyclin-depend- ent kinases (CDK)4 and CDK2 in overexpression and knockdown of RPL26 stably transfected cell lines . Results: Compared with GES-1 , RPL26 was highly expressed in HGC-27 cells ( tHGC-27 = 4. 97 ; P < 0. 01) and elevated in AGS , but the difference was not statistically significant. In HGC-27 and AGS cells , CCK-8 and colony formation assays showed that the proliferation ability of cells decreased after the knockdown of RPL26. Transwell assay showed that the migration ability of cells decreased after the knockdown of RPL26. Western blot showed that Bcl-2 expression was decreased in HGC-27 , AGS cells after the knockdown of RPL26 ( tHGC-27 = 11 . 50 , tAGS = 4. 77 ; P < 0. 001 , P < 0. 01) , and Bax expression increased ( tHGC-27 = 9. 63 , tAGS = 4. 05 ; P < 0. 001 , P < 0. 05) . In HGC-27 cells , the ratios of p-PI3K/PI3K and p-AKT/AKT significantly decreased after the knockdown of RPL26 ( tp-PI3K/PI3K = 3 . 86 , tp-AKT/AKT = 8. 29 ; P < 0. 05 , P < 0. 01) . Cyclin A , Cyclin D1 , CDK4 , CDK2 protein expressions de- creased ( t = 9. 61 , 5 . 10 , 11 . 64 , 7. 81 ; P < 0. 01 or P < 0. 001) , while the overexpression of RPL26 in HGC-27 cells showed the opposite trend . Conclusion The knockdown of RPL26 may arrest the cell cycle in G1 /S phase by inhibiting the PI3K/AKT signaling pathway , thereby inhibiting cell proliferation and promoting apoptosis .

Objective To compare functional differences of CD8+T cells in lung tissues between young and aged C57BL/6J mice during the contraction phase and memory immune response phase after infection with influenza A(H1N1)virus.Methods Lung tissues from young(3-month-old)and aged(24-month-old)C57BL/6J female mice without influenza virus infection were collected to prepare single-cell suspensions,which were stimulated with phorbol 12-myristate 13-acetate(PMA)/ionomycin or cluster of differentiation(CD)3/CD28 antibodies(T-cell antigen receptor/co-stimulatory signals)respectively(non-specific antigens stimulation).Flow cytometry intracellular cytokine staining(ICS)was performed on lung CD8+T cells to detect their secretion capacity of tumor necrosis factor-α(TNF-α)and interferon-γ(IFN-γ).Young and aged C57BL/6J mice were infected intranasally with 490 PFU PR8 influenza virus,and reinfected with homologous influenza virus 28 days later.Lung tissues were isolated on day 28(the contraction phase)and day 32(the memory immune response phase)after primary infection.Influenza virus-specific MHC-Ⅰ tetramer staining was used to detect the proportion of virus-specific CD8+T cells in lung tissue CD8+T cells,and ICS was used to analyze TNF-α,IFN-γ,and granzyme B expression in CD8+CD44high T cell subset.Results After non-specific antigen stimulation,TNF-α and IFN-γ secretion capacity in lung tissue CD8+T cells of aged group mice was significantly higher than that of young group(P＜0.05).After virus-specific antigen stimulation,there were no statistically significant differences in the proportion of virus-specific CD8+T cells and the expression levels of TNF-α,IFN-γ,and granzyme B between the two groups of mice during the contraction phase(P＞0.05),while during the memory immune response phase,the proportion of virus-specific CD8+T cells and the expression levels of TNF-α,IFN-γ,and granzyme B in the aged group mice were significantly lower than those in the young group(P＜0.05).Conclusion CD8+T cells in aged mice maintain normal immune-related factor expression function under non-specific antigen stimulation,but show impaired immune-related factor expression function during antigen-specific memory immune response phase,suggesting that aging leads to defects in the formation or maintenance of CD8+T cell immune memory.

Objective:To explore the time variations of the influence of the ultra-high dose rate irradiation (FLASH irradiation, FLASH-IR) and conventional dose rate irradiation (CONV-IR) of electron beams under different doses on the energy metabolism of triple-negative breast cancer cells MDA-MB-231.Methods:The basal metabolism of the MDA-MB-231 cells and normal breast epithelial cells MCF-10A was compared using a Seahorse XF Pro Metabolic Analyzer. Based on an irradiation platform with a thermionic cathode electron accelerator (6 MeV), the MDA-MB-231 cells were exposed to FLASH-IR (106 Gy/s) and CONV-IR (0.1 Gy/s) at 2 and 14 Gy, respectively. Meanwhile, a sham irradiation group was established under identical culture conditions. The mitochondrial metabolism and glycolytic metabolism of the cells at 4, 24, and 48 h post-irradiation were analyzed.Results:Compared to the MCF-10A cells, the MDA-MB-231 cells exhibited a greater reliance on glycolytic metabolism. Compared to those of the sham irradiation group, MDA-MB-231 cells in the 2 Gy CONV-IR group showed up-regulated ATP-linked respiration at 4, 24, and 48 h post-irradiation ( t = 2.69-3.70, P < 0.05). Their glycolytic level and glycolytic capacity were up-regulated only at 4 h post-irradiation and were down-regulated at 48 h ( t = 2.79, -4.44, P < 0.05). In contrast, there was no statistically significant difference in these indicators between the FLASH-IR and CONV-IR groups ( P > 0.05). However, the proton leak of the MDA-MB-231 cells in the FLASH-IR group was relatively down-regulated at 4 h post-irradiation and was significantly up-regulated at 24 h and 48 h post-irradiation compared with the CONV-IR group ( t = -2.45, 3.19, 6.51, P < 0.05). At 14 Gy, the MDA-MB-231 cells in the CONV-IR group showed progressively increased mitochondrial and glycolytic metabolism across all time points ( t = 2.48-12.14, P < 0.05). Notably, compared with the CONV-IR group, the MDA-MB-231 cells in the FLASH-IR group exhibited more significantly up-regulated basal respiration, ATP-linked respiration, and non-mitochondrial oxygen consumption ( t = 2.56-6.51, P < 0.05), as well as a higher glycolytic capacity at 24 h post-irradiation ( t = 2.86, P < 0.05). Conclusions:Low-dose (2 Gy) FLASH-IR induces relatively up-regulated proton leak in breast cancer cells MDA-MB-231 at 24 h post-irradiation. In contrast, under high-dose (14 Gy) FLASH-IR, the MDA-MB-231 cells show more pronounced mitochondrial metabolic stress and a higher demand for energy metabolism.