[Research progress in methylation modification in tooth root development]

Methylation modification is one of the most common epigenetic modification regulation in eukaryotes, including histone methylation, DNA methylation, RNA methylation, etc., which plays an important regulatory role in physiological processes and pathologic occurrence and development. Tooth root development is carried out by both epithelial and mesenchymal cells and involves a variety of cell-molecular interactions. In recent years, a large number of studies have found that methylation plays a key role in the regulation of tooth root development and expands the mechanism network of tooth root development. In this paper, we review the role and mechanism of methylation modification during root development.

Potential Use of Extracellular Vesicles in the Treatment of Intervertebral Disc Degeneration

Intervertebral disc degeneration (IVDD) is a major cause of low back pain, and several studies have evaluated the efficacy of extracellular vesicles (EVs) in the treatment of IVDD. The databases PubMed, Embase, and Cochrane Library were systematically searched from inception to the end of 2022 to identify studies investigating the therapeutic potential of cell-derived EVs for IVDD treatment. The following outcome measures were utilized: magnetic resonance imaging (MRI) Pfirrmann grading system, disc height index (DHI), histological grading, and apoptosis rate. A comprehensive meta-analysis was conducted, including a total of 13 articles comprising 19 studies involving 218 experimental animals. Comparative analysis between normal cell-derived EVs and placebo revealed significant reductions in MRI grade, increased DHI values, decreased nucleus pulposus cell apoptosis rates, and improved tissue grades. These findings collectively demonstrate the effective inhibition of IVDD through the application of EVs derived from cells. In conclusion, this study provides an updated synthesis of evidence supporting the efficacy of EVs as a promising therapeutic approach for IVDD treatment.

Sequencing and bioinformatics analysis of miRNA from rat endplate chondrogenic exosomes

Exosomes have a key role in various diseases, such as arthritis, heart disease and respiratory disease. Exosomes from various sources have also been indicated to improve intervertebral disc degeneration. However, the role of endplate chondrogenic exosomes in intervertebral disc degeneration has remained largely elusive. The aim of the present study was to compare exosomal microRNA (miRNA) expression patterns in endplate chondrocytes before and after degeneration, and their potential roles in the pathogenesis of intervertebral disc degeneration (IVDD). Endplate chondrocytes were extracted from rats and cultured to obtain pre- and post-degeneration chondrocytes. Exosomes were obtained from the chondrocytes by centrifugation. The two groups of exosomes were subjected to small RNA sequencing, miRNA identification, novel miRNA prediction, quantitative analysis of miRNA expression and differentially expressed (DE) miRNA screening, in addition to miRNA target gene (TG) prediction and TG functional annotation and enrichment analysis. The percentage of miRNAs isolated from the exosomes before and after degeneration was found to differ. A total of 58 DE miRNAs were analyzed, the expression levels of which were significantly different post-degeneration compared with pre-degeneration. Cell experiments were also performed, in which the exosomes were co-cultured with nucleus pulposus (NP) cells. The results indicated that the chondrocyte-derived exosomes were taken up by the NP cells and influenced the expression of aggrecan and collagen 1A and 2A, suggesting that they may inhibit IVDD via their action on NP cells. The specific miRNAs present in exosomes during IVDD may be used to develop new targets for the treatment and diagnosis of this condition. DE exosomal miRNAs derived from endplate cartilage pre- and post-degeneration may be associated with the risk of IVDD and could help to distinguish patients with IVDD. Furthermore, the expression of certain miRNAs may be associated with disease progression, which may contribute to understanding the pathophysiology of IVDD from an epigenetic perspective.

[Effects of comprehensive treatment of infected wounds in patients with iatrogenic Cushing's syndrome]

Objective: To investigate the characteristics and comprehensive treatment of infected wounds in patients with iatrogenic Cushing's syndrome. Methods: A retrospective observational study was conducted. From May 2012 to December 2021, the data of 19 patients with iatrogenic Cushing's syndrome discharged from the Department of Burns and Plastic Surgery of the First Affiliated Hospital of Guangxi Medical University were collected, including 8 males and 11 females, aged 28-71 (56±11) years, with 12 cases of infected acute wounds and 7 cases of infected chronic wounds. The lesions were located in the limbs, perianal, and sacrococcygeal regions, with original infection ranging from 9 cm×5 cm to 85 cm×45 cm. After admission, the patients were performed with multidisciplinary assisted diagnosis and treatment, and the wounds were treated with debridement and vacuum sealing drainage, according to the size, severity of infection, suture tension, and bone and tendon tissue exposure of wounds, direct suture or autologous skin and/or artificial dermis and/or autologous tissue flap transplantation was selected for wound repair. The levels of cortisol and adrenocorticotropic hormone (ACTH) of patients at 8:00, 16:00, and 24:00 within 24 h after admission were counted. After admission, the number of operations, wound repair methods, and wound and skin/flap donor site healing of patients were recorded. During follow-up, the wounds were observed for recurrent infection. Results: The cortisol levels of 16 patients at 8:00, 16:00, and 24:00 within 24 h after admission were (130±54), (80±16), and (109±39) nmol/L, respectively, and ACTH levels were (7.2±2.8), (4.1±1.8), and (6.0±3.0) pg/mL, respectively; and the other 3 patients had no such statistical results. After admission, the number of surgical operation for patients was 3.4±0.9. The following methods were used for wound repair, including direct suturing in 4 cases and autologous skin and/or artificial dermis grafting in 9 cases, of which 2 cases underwent stage Ⅱ autologous skin grafting after artificial dermis grafting in stage Ⅰ, and 6 cases had pedicled retrograde island flap+autologous skin grafting. The wound healing was observed, showing that all directly sutured wounds healed well; the wounds in 6 cases of autologous skin and/or artificial dermis grafting healed well, and the wounds in 3 cases also healed well after the secondary skin grafting; the flaps in 4 cases survived well with the wounds in 2 cases with distal perforators flap arteries circumfluence obstacle of posterior leg healed after stage Ⅱ debridement and autologous skin grafting. The healing status of skin/flap donor sites was followed showing that the donor sites of medium-thickness skin grafts in the thigh of 4 cases were well healed after transplanted with autologous split-thickness grafts from scalp; the donor sites of medium-thickness skin grafts in 3 cases did not undergo split-thickness skin grafting, of which 2 cases had poor healing but healed well after secondary skin grafting 2 weeks after surgery; the donor sites of split-thickness skin grafts in the head of 2 patients healed well; and all donor sites of flaps healed well after autologous skin grafting. During follow-up of more than half a year, 3 gout patients were hospitalized again for surgical treatment due to gout stone rupture, 4 patients were hospitalized again for surgical treatment due to infection, and no recurrent infection was found in the rest of patients. Conclusions: The infected wounds in patients with iatrogenic Cushing's syndrome have poor ability to regenerate and are prone to repeated infection. Local wound treatment together with multidisciplinary comprehensive treatment should be performed to control infection and close wounds in a timely manner, so as to maximize the benefits of patients.

[Multivariate analysis of the effect of two liver resection methods on the survival outcome of patients with intrahepatic cholangiocarcinoma]

Objective: To investigate the effect of anatomical hepatectomy and non-anatomic hepatectomy in the treatment of elderly patients with intrahepatic cholangiocarcinoma (IHCC) and their impact on survival outcomes. Methods: In this study, a retrospective method was used to select elderly patients with IHCC who were surgically treated in Shangqiu First People's Hospital from April 2014 to April 2018, and were divided into anatomic resection group and non-anatomical resection group according to the surgical methods they received.The factors affecting the survival outcome of IHCC in the two liver resection methods were analyzed and compared, as well as the effects of liver cirrhosis rate, TNM stage, ascites rate, lymph node metastasis rate, and vascular invasion rate on survival. Results: A total of 181 cases were included in this study, including 87 cases in the anatomical resection group, with 54 males and 33 females, aged (71.4±5.2) years old;There were 94 cases in the non-anatomical resection group, including 49 males and 45 females, aged (70.8±4.8) years.The 3-year survival rate of the anatomical resection group was 41.4% (36/87), which was higher than that of the non-anatomical resection group (25.5% (24/94), the difference was statistically significant (P<0.05);The median survival time of the anatomic resection group was longer than that of the non-anatomical resection group, and the difference was statistically significant P<0.05;The patient's TNM stage was stage III [OR (95%CI): 2.168 (1.245-3.776)], lymph node metastasis [1.664 (1.087-2.545)], and vascular invasion [1.883 (1.167-3.038)] was an independent risk factor for death 3 years after surgery (P<0.05), The patient's anatomical liver resection was a protective factor for the 3-year follow-up survival (P<0.05). Conclusion: The postoperative survival of elderly patients with IHCC is affected by many factors, but anatomic liver resection is beneficial to prolong the survival time of patients.

[A case-control study:the clinical efficacy of total laminectomy with lateral mass screw fixation and single open-door laminoplasty for cervical spinal cord injury without fracture and dislocation]

OBJECTIVE

To compare the clinical effects of total laminectomy with lateral mass screw fixation and single open-door laminoplasty in the treatment of cervical spinal cord injury without fracture and dislocation.

METHODS

The clinical data of 75 patients with cervical spinal cord injury without fracture and dislocation treated from December 2014 to April 2020 were retrospectively analyzed, including 65 males and 10 females, aged from 33 to 83 years old with an average of (60.1±11.4) years. According to surgical method, the patients were divided into observation group (36 cases) and control group (39 cases). The observation group was treated with C₃-C₆ single open-door laminoplasty. In the control group, the C₃-C₆ whole lamina was opened by "uncovering", and the lateral mass screw was fixed and fused. The general conditions including operation time, intraoperative blood loss, hospital stay and complications such as axial pain, cerebrospinal fluid leakage, postoperative C₅ nerve palsy were recorded. Visual analogue scale(VAS), Nurick pain scale, Japanese Orthopaedic Association(JOA) scores and American Spinal Injury Association(AISA) injury scale were used to evaluate the improvement of clinical symptoms and related functional recovery 12 months after operation.

RESULTS

There were no statistically significant differences in operation time, intraoperative blood loss and hospital stay between two groups(P>0.05). There were statistically significant differences in JOA, VAS, ASIA and Nurick scores of the all patients between 12 months after surgery and before surgery (P<0.05), and there was no significant difference between groups. There was significant difference in the incidence of C5 nerve root palsy and axial pain between two groups(P<0.05), but there was no significant difference in the complications of cerebrospinal fluid leakage between two groups (P>0.05).

CONCLUSION

Total laminectomy with lateral mass screw fixation and single open-door laminoplasty in treating cervical spinal cord injury without fracture and dislocation can obtain satisfactory results in restoring nerve function, alleviating pain and improving daily behavior, but single open-door laminoplasty has the advantages of less trauma and low incidence of complications.

A hybrid gene selection method based on gene scoring strategy and improved particle swarm optimization

Background

Gene selection is one of the critical steps in the course of the classification of microarray data. Since particle swarm optimization has no complicated evolutionary operators and fewer parameters need to be adjusted, it has been used increasingly as an effective technique for gene selection. Since particle swarm optimization is apt to converge to local minima which lead to premature convergence, some particle swarm optimization based gene selection methods may select non-optimal genes with high probability. To select predictive genes with low redundancy as well as not filtering out key genes is still a challenge.

Results

To obtain predictive genes with lower redundancy as well as overcome the deficiencies of traditional particle swarm optimization based gene selection methods, a hybrid gene selection method based on gene scoring strategy and improved particle swarm optimization is proposed in this paper. To select the genes highly related to out samples’ classes, a gene scoring strategy based on randomization and extreme learning machine is proposed to filter much irrelevant genes. With the third-level gene pool established by multiple filter strategy, an improved particle swarm optimization is proposed to perform gene selection. In the improved particle swarm optimization, to decrease the likelihood of the premature of the swarm the Metropolis criterion of simulated annealing algorithm is introduced to update the particles, and the half of the swarm are reinitialized when the swarm is trapped into local minima.

Conclusions

Combining the gene scoring strategy with the improved particle swarm optimization, the new method could select functional gene subsets which are significantly sensitive to the samples’ classes. With the few discriminative genes selected by the proposed method, extreme learning machine and support vector machine classifiers achieve much high prediction accuracy on several public microarray data, which in turn verifies the efficiency and effectiveness of the proposed gene selection method.

[Efficacy of Weitan Waifu patch on the postsurgical gastroparesis syndrome of gastrointestinal cancer: a multi-center trial]

Objective: To investigate the safety and efficacy of the Weitan Waifu patch on the postsurgical gastroparesis syndrome (PGS) of gastrointestinal cancer. Methods: The multi-center, double-blind, randomized controlled trial was conducted with superiority design. Patients with PGS of gastrointestinal cancer diagnosed in 4 AAA hospitals and the abdominal symptom manifested as cold syndrome by Chinese local syndrome differentiation were recruited. These patients were randomly divided into two groups according to 1∶1 proportion. Placebo or Weitan Waifu patch was applied in control group or intervention group, respectively, based on the basic treatments, including nutrition support, gastrointestinal decompression, promoting gastric dynamics medicine.Two acupuncture points (Zhongwan and Shenque) were stuck with placebo in control group or patch in treatment group. The intervention course was 14 days or reached the effective standard. Results: From July 15, 2013 to Jun 3, 2015, 128 participants were recruited and 120 eligible cases were included in the full analysis set (FAS), and 60 cases in each group. 88 cases were included in the per-protocol set (PPS), including 45 cases in the treatment group and 43 cases in the control group. In the FAS, the clinical effective rate in the treatment group was 68.3%, significantly superior than 41.7% of the control group (P=0.003). The medium time of effective therapy in the treatment group was 8 days, significantly shorter than 10 days in the control group (P=0.017). In the FAS, 3 adverse events occurred in the treatment group, including mild to moderate decrustation, pruritus and nausea. The incidence rate of adverse events was 5.0% (3/60) and these symptoms were spontaneously remitted after drug withdrawal. No severe adverse events were observed in the control group. There was no significant difference between these two groups (P=0.244). Conclusion: Weitan Waifu patch is a safely and effectively therapeutic method for patients with PGS (cold syndrome) of gastroenterological cancer. Trial registration: International Standard Randomized Controlled Trial Number Register, ISRCTN18291857.

[The CK2 inhibitor quninalizarin enhances the anti-proliferative effect of icotinib on EGFR-TKIs-resistant cell lines and its underlying mechanisms]

OBJECTIVE

To explore whether quninalizarin, an specific inhibitor of protein kinase CK2, could sensitize icotinib in EGFR-TKIs (epithelial growth factor receptor-tyrosine kinase inhibitor)-resistant cell lines and uncover the underlying mechanisms.

METHODS

MTT assay was performed to evaluate the inhibitory effect of quninalizarin, icotinib or the combination of both on cell proliferation in several lung adenocarcinoma cell lines. Western blot assay was used to assess if combined inhibition of EGFR and protein kinase CK2 by icotinib and quninalizarin, exerts effect on the expression and phosphorylation of major proteins of EGFR signaling pathways.

RESULTS

The IC50 of HCC827, H1650, H1975 and A549 cells for icotinib were (8.07±2.00)μmol/L, (66.01±6.64)μmol/L, (265.60±9.47)μmol/L and (87.88±6.8)μmol/L, respectively, indicating that HCC827 cells are sensitive to icotinib, and the H1650, H1975 and A549 cells are relatively resistant to icotinib. When treated with both quninalizarin and icotinib in the concentration of 50 μmol/L, the viability of H1650, H1975 and A549 cells was (40.64±3.73)%, (65.74±3.27)% and (44.96±0.48)%, respectively, significantly lower than that of H1650, H1975 and A549 cells treated with 50 μmol/L icotinib alone (55.05±1.22)%, (71.98±1.60)% and (61.74±6.18)%, respectively (P<0.01 for all). When treated with both 100 μmol/L quninalizarin and 100 μmol/L icotinib, the viability of H1650, H1975 and A549 ells were (23.35±0.81)%, (55.70±1.03)%, (33.42±1.33)%, respectively, significantly lower than the viability of H1650, H1975 and A549 cells treated with 100 μmol/L icotinib alone (40.57±2.65)%, (62.40±2.05)% and (44.97±8.20)%, respectively, (P<0.01 for all). The two-way ANOVA analysis showed that compared with the viability of EGFR-TKIs-resistant cells (H1650, H1975, A549) treated with 50 μmol/L and 100 μmol/L icotinib alone, the viability of cells treated with icotinib and quinalizarin were significantly suppressed, and the differences were statistically significant (P<0.01). In addition, the phosphorylation form of Akt and ERK (namely p-Akt and p-ERK) were significantly down-regulated by treating with quninalizarin and icotinib together in the H1650 cells while the expression of Akt and ERK changed little.

CONCLUSIONS

Quinalizarin, as a specific CK2 inhibitor, may overcome icotinib resistance by inhibiting proliferation mediated by Akt and ERK in human lung adenocarcinoma cell lines, and enhances the suppressive effect of icotinib on the proliferation of EGFR-TKIs-resistant human lung adenocarcinoma cells.

MicroRNA-215 functions as a tumor suppressor and directly targets ZEB2 in human pancreatic cancer

It has been shown that microRNA-215 (miR-215) is dysregulated in several human malignancies, and this correlates with tumor progression. However, its expression and function in pancreatic cancer is still unclear. The aim of this study was to explore the effects of miR-215 on pancreatic cancer formation and progression. Using quantitative RT-PCR, we detected miR-215 expression in pancreatic cancer cell lines and primary tumor tissues. The association of miR-215 expression with clinicopathological factors and prognosis was also analyzed. We then observed the effects of miR-215 on the biological behavior of pancreatic cancer cells. Lastly, the potential regulatory function of miR-215 on ZEB2 expression was investigated. miR-215 expression levels were significantly downregulated in pancreatic cancer samples and cell lines. Decreased miR-215 expression was significantly associated with large tumor size, advanced TNM stage, lymph node metastasis, vessel invasion, and lower overall survival. Multivariate regression analysis corroborated that downregulation of miR-215 was an independent unfavorable prognostic factor. Overexpression of miR-215 inhibited pancreatic cancer cell proliferation, invasion, and migration; promoted cell apoptosis in vitro; and suppressed tumorigenicity in vivo. Further, ZEB2 was confirmed as a direct target of miR-215 by using a luciferase reporter assay. These findings indicate that miR-215 may act as a tumor suppressor in pancreatic cancer cells, and could serve as a novel therapeutic target for miR-based therapy.

FOXO1 is a tumor suppressor in cervical cancer

Forkhead box protein O1 (FOXO1) is an important transcriptional regulator of cell proliferation, and is considered essential for tumor growth and progression. However, the function of FOXO1 in human cervical cancer remains unclear. In this study, we investigated the role of FOXO1 in cervical cancer. Our results showed that FOXO1 expression was lower in cervical cancer than in cervical intraepithelial neoplasia and normal cervix by immunohistochemical analysis (P < 0.05). The level of FOXO1 in high-grade lesions was significantly lower than in low-grade lesion (P < 0.05), indicating that deficient expression of FOXO1 is involved in tumor progression and significantly associated with late-stage tumors (P < 0.05), which was further supported by clinicopathological, real-time polymerase chain reaction, and Western blotting analysis. Moreover, we confirmed that the overexpression of FOXO1 remarkably repressed cell growth and blocked cell proliferation, accompanied by cell-cycle arrest in the G2/M phase and upregulation of caspases-3 and -9 gene expression. Collectively, our data suggest that FOXO1 plays a vital role in inhibiting cervical cancer development by inducing cell-cycle arrest and apoptosis. FOXO1 expression is a favorable prognostic factor for human cervical cancer.

Genetic diversity of Saccharum spontaneum from geographical regions of China assessed by simple sequence repeats

Saccharum spontaneum is the most variable wild relative of sugarcane with potential for use in sugarcane improvement programs. In order to help preserve and exploit this species, 152 accessions from eight major geographical regions in China, including Hainan, Guangdong, Guangxi, Yunnan, Sichuan, Guizhou, Fujian, and Jiangxi provinces, were investigated by analyzing 20 simple sequence repeats (SSRs), including 11 genomic SSRs (gSSRs) and nine SSRs developed from expressed sequence tags (EST-SSRs). A total of 454 alleles were generated by the 20 SSRs, with 295 and 159 alleles detected by gSSRs and EST-SSRs respectively. The Mantel test showed significant correlation between genetic matrixes among the studied accessions revealed by gSSRs versus EST-SSRs, although the average polymorphism of EST-SSRs (17.7) was much lower than that of gSSRs (26.8). Among the eight provinces, collections from Guizhou were the most diverse and those from Guangdong were the most distinct. Clustering analysis and principal component analysis accordantly classified the accessions into four groups, which were "Southwest group", "Hainan group", "Guangdong group", and "Guangxi group", based on the geographical origin of the major accessions in each group, demonstrating that geographical factors play an important role in the pattern of genetic structure of Chinese S. spontaneum. As two (Guizhou and Yunnan) of the three provinces with highest genetic diversity are located in southwest China, we concluded that southwest China is the region with the highest genetic diversity of S. spontaneum.

Heralded generation of multipartite entanglement for one photon by using a single two-dimensional nonlinear photonic crystal

We propose a compact scheme for the heralded generation of single-photon multipartite entanglement by using a single two-dimensional nonlinear photonic crystal. Studies have shown that by appropriate structure design, the single-photon entanglement shared among three spatially distinct optical modes can be generated through three concurrent spontaneous parametric down-conversion processes by using the other photon in an identical spatial mode as a trigger. Furthermore, we analyze the entanglement of such heralded single-photon tripartite W-type state theoretically. This method can be expanded for the heralded single-photon N-partite entanglement generation. This compact and stable quantum light source may act as a key ingredient in quantum information science.

Cloning and characterization of A cDNA encoding prohibitin1 from Lampetra japonica and its expression analysis

To investigate that prohibitin is probably concerned in B--lymphocyte--like cells mediated signal pathways in Lamprey, a necessary and fundamental plan is firstly conducted. A full--length cDNA encoding the prohibitin1 protein was cloned from Lampetra japonica by EST sequence analysis in L. japonica leukocyte cDNA library conducted by our laboratory. Prohibitin1 contains a 828 bp open reading frame, encoded 275 amino acids residues, and molecular weight is 29.9517 KD, isoelectric point is 6.93, consists of 31 negatively charged amino acids residues (Asp+Glu) and 21 positively charged ones (Arg+Lys). The Prohibitin1 gene sequence from L. japonica is 71% identical to the ones of other 24 eukaryotic species, which shows the putative prohibitin1 gene is highly conserved. Western blotting analysis results showed the recombinant proteins were the target proteins in prokaryote. Real--time quantitative polymerase chain reaction analysis indicated that the expression of the prohibitin1 gene is significantly up--regulated in leukocyte, heart and gill of L. japonica by LPS stress treatment. In conclusion, we have cloned and identified the full--length cDNA of Prohibitin1 in L. japonica and found that it was related to adaptive immune response in lamprey for the first time.

[Surgical repair of hypospadias with urethral burying and scrotal skin flap transplantation]

OBJECTIVE

To investigate the surgical approach to repair hypospadias.

METHODS

From 1992 to 2000, 42 cases with hypospadias accepted secondary urethroplasty after primary operation, which included urethral burying in penile skin, bladder mucosa and scrotal septal vascular pedicled flap urethroplasty, trans-scrotal skin flap covering the wounds with normal meatus urinarius.

RESULTS

Only one, out of 42 cases, had early complication of urinary fistula in 7 days after urethroplasty, which was cured by scrotal septal vascular pedicled flap urethroplasty 3 months later and had no further complication. The others were all succeeded once for all, the successful rate was 97.6%.

CONCLUSION

The surgical method to repair hypospadias by urethral burying and transscrotal skin flap technique is safe, reliable and recommendable for clinical use.

[Studies on chemical constituents of Lagopsis supina (Steph.) Ik.-GaI]

OBJECTIVE

To study the chemical constituents of Lagopsis supina.

METHOD

Compounds were separated by solvent extraction, column chromatography and TLC, and the structures were determined by chemical and spectral analyses.

RESULTS

Six compounds were isolated from the ethanol extract of L. supina and identified as eicosanoic acid octadecyl ester, eicosanoic acid-16-methyl-15, 16-hetadecenyl ester, palmitic acid, beta-sitosterol, oleanolic acid and daucosterol.

CONCLUSION

Except beta-sitosterol, all the compounds were isolated from this genus for the first time.

[The effect of IUD on endometrial blood vessels--correlation between vascular changes and bleeding]

In order to examine the causes of endometrial bleeding following IUD insertion, 22 samples of endometrium from women with an IUD in place for between 1-20 years or more and 10 cases of endometrium without an IUD and with normal menstrual cycles as controls were studied. The quantitative histologic method was utilized to demonstrate the correlation between vascular changes and clinical bleeding. The results indicate that the concentration and expansion of microvascularity, especially the capillary, venule, and venous sinus, increased significantly in most of the IUD-exposed endometriums (75%) as compared with controls (p0.01). The remarkable changes in vessels correlated with clinical bleeding were increased density, obvious dilatation, defect, and rupture of the superficial venous sinus. Mechanical damage, degeneration, necrosis, and denudation of surface endometrium exposed to the IUD could be the direct cause of clinical bleeding.