Neuroprotective effects of human telomerase reverse transcriptase on beta-amyloid fragment 25-35-treated human embryonic cortical neurons

BACKGROUND： Numerous current studies have suggested that human telomerase reverse transcriptase （hTERT） gene has neuroprotective effects and can inhibit apoptosis induced by various cytotoxic stresses; however, the mechanism of action remains unknown. OBJECTIVE： To evaluate the neuroprotective effects and possible mechanism of action of hTERT gene transfection in human embryonic cortical neurons treated with beta-amyloid fragment 25-35 （AI325-35）. DESIGN, TIME AND SETTING： The randomized, controlled and molecular biological studies were performed at the Department of Anatomy and Brain Research, Zhongshan School of Medicine, Sun Yat-sen University, China, from September 2005 to June 2008. MATERIALS： AdEasy-1 Expression System was gifted by Professor Guoquan Gao from Sun Yat-Sen University, China. Human cortical neurons were derived from 12-20 week old aborted fetuses, obtained from the Guangzhou Maternal and Child Health Hospital, China. Mouse anti-Odk5 and mouse anti-p16 monoclonal antibodies （Lab Vision, USA）, and mouse anti-hTERT monoclonal antibody （Epitomics, USA）, were used in this study. METHODS： （1） Recombinant adenovirus vectors, encoding hTERT （Ad-hTERT） and green fluorescent protein （Ad-GFP）, were constructed using the AdEasy-1 Expression System. Human embryonic cortical neurons in the Ad-hTERT group were transfected with Ad-hTERT for 1-21 days. Likewise, human embryonic cortical neurons in the Ad-GFP group were transfected with Ad-GFP for 1-21 days. Human embryonic cortical neurons in the control group were cultured as normal. （2） Human embryonic cortical neurons in the Ad-hTERT group were treated with 10 pmol/L Aβ25-35 for 24 hours. Normal human embryonic cortical neurons treated with 10 pmol/Lβ25.35 for 24 hours served as a model group. Human embryonic cortical neurons in the Ad-GFP and control groups were not treated with Aβ25-35. MAIN OUTCOME MEASURES： Expression of hTERT in human embryonic cortical neurons was evaluated by immunocytochemical staining and Western blot assay. Telomerase activity was measured using a PCR-based telomeric repeat amplification protocol （TRAP） ELISA kit. Neural activity in human embryonic cortical neurons was examined by MTT assay; apoptosis was measured using TUNEL assay; and Cdk5 and p16 protein expressions were measured by Western blot. RESULTS： Expression of hTERT protein was significantly increased and peaked at day 3 post-transfection in the Ad-hTERT group. No hTERT expression was detected in the Ad-GFP and control groups. Telomerase activity was significantly greater in the Ad-hTERT group compared with the Ad-GFP and control groups （P 〈 0.01）. Compared with the control group, cell activity was significantly decreased （P 〈 0.05）, and cell apoptotic rate, Cdk5 and p16 expression were significantly increased （P 〈 0.01） in the model group. Compared with the model group, cell activity was increased in the Ad-hTERT group, and peaked at day 3 post-transfection （P 〈 0.05）. Neuroprotective effects also peaked at day 3 post-transfection; and the apoptotic rate, Cdk5 and p16 expression significantly decreased （P 〈 0.01）. CONCLUSION： Expression of hTERT in human embryonic cortical neurons can relieve Aβ25-35-induced neuronal apoptosis. The possible mechanism by which hTERT produces these neuroprotective effects may be associated with inhibition of Cdk5 and p16 expression.

Development of a sensitive and rapid method for quantitation of (S)-(-)- and (R)-(+)-metoprolol in human plasma by chiral LC–ESI–MS/MS

A selective, sensitive and high throughput liquid chromatography-tandem mass spectro-metry （LC-ESI-MS/MS） method has been developed for separation and quantification of metoprolol enantiomers on a chiral Lux Amylose-2 （250 mm＆#215;4.6 mm, 5 mm） column. Solid phase extraction of （S）-（-）- and （R）-（t）-metoprolol and rac-metoprolol-d6 as an internal standard （IS） was achieved on Lichrosep DVB HL cartridges employing 200 mL human plasma. Both the analytes were chromatographically separated with a resolution factor of 2.24 using 15 mM ammonium acetate in water, pH 5.0 and 0.1% （v/v） diethyl amine in acetonitrile （50：50, v/v） as the mobile phase within 7.0 min. The precursor-product ion transitions for the enantiomers and IS were monitored in the multiple reaction monitoring and positive ionization mode. The method was validated over the concentration range of 0.500-500 ng/mL for both the enantiomers. Matrix effect was assessed by post-column analyte infusion experiment and the mean extraction recovery was greater than 94.0% for both the enantiomers at all quality control levels. The stability of analytes was evaluated in plasma and whole blood under different storage conditions. The method was successfully applied to a clinical study in 14 healthy volunteers after oral administration of 200 mg metoprolol tablet under fasting conditions. The assay reproducibility is shown by reanalysis of 68 incurred samples. The suitability of the developed method was assessed in comparison with＆amp;nbsp;different chromatographic methods developed for stereoselective analysis of metoprolol in biological matrices.

THE DIFFERENTIATION OF HUMAN GASTRIC ADENOCAR-CINOMA CELL LINE MGc80-3 INDUCED BY DIBUTYRYL cAMP IN VITRO

For providing some experimental basis in establishing malignant phenotypic reversed indexes of gastric carcinoma cells, human gastric adenocar-cinoma cell line MGc80-3 was induced by dBcAMP in vitro to appraise the effect of gastric carcinoma cell differentiation by chemical inducers.Under light microscope, MGc80-3 cells, after treated with 1 mM dBcAMP, tended to be flat and disperse, and their volume gradually enlarged, with their uncleus relatively smaller and their shape rather regular. Morphological changes, like norma differentiated epithelial cells, were observed. The cells attached firmly, grew slowly, their growth curve showed inhibitory rate amounted to 52.87%, and cellular division exponent displayed their peak value 1.5 times less than that of MGc80-3 cells. It was clear that dBcAMP could effectively inhibit the multiplication activity of MGc80-3 cells. After dBcAMP treatment, remarkable changes of cell surface charges was indicated by cell electrophoresis, the ratio dropped to 3.043 from 3.988, and their re-tardant ratio reached up to 31.2%. cAMP content in cells after this treatment, detected by cAMP and cGMP radioimmunoassay, was enhanced by 2.42 times, and cAMP/cGMP ratio, by 1.73 times. Thus, cAMP level within MGc80-3 cells was raised obviously by dBcAMP. Heterotransplantation experiments showed that tuntorigenic rate of MGc80-5 cells (transplanted subcutaneously to BALB/c mice) amounted to 100%, and that of the cells after this treatment was only 5.6%. Their tumorigenic ability was extremely reduced.These results confirmed that dBcAMP was able to change malignant phenotypic characteristics of MGc80-3 cells and produce a reversed alteration: Thus, it has a remarkable inductive effect in differentiating gastric carcinoma cells. All these characteristics were also considered as the reference indexes in appraising reversed effect for the homologous cancer cells.

circ_0003204 regulates the osteogenic differentiation of human adipose-derived stem cells via miR-370-3p/HDAC4 axis

Human adipose-derived stem cells(hASCs)are a promising cell type for bone tissue regeneration.Circular RNAs(circRNAs)have been shown to play a critical role in regulating various cell differentiation and involve in mesenchymal stem cell osteogenesis.However,how circRNAs regulate hASCs in osteogenesis is still unclear.Herein,we found circ_0003204 was significantly downregulated during osteogenic differentiation of hASCs.Knockdown of circ_0003204 by si RNA or overexpression by lentivirus confirmed circ_0003204 could negatively regulate the osteogenic differentiation of hASCs.We performed dual-luciferase reporting assay and rescue experiments to verify circ_0003204 regulated osteogenic differentiation via sponging miR-370-3p.We predicted and confirmed that miR-370-3p had targets in the 3′-UTR of HDAC4 m RNA.The following rescue experiments indicated that circ_0003204 regulated the osteogenic differentiation of hASCs via miR-370-3p/HDAC4 axis.Subsequent in vivo experiments showed the silencing of circ_0003204 increased the bone formation and promoted the expression of osteogenic-related proteins in a mouse bone defect model,while overexpression of circ_0003204 inhibited bone defect repair.Our findings indicated that circ_0003204 might be a promising target to promote the efficacy of hASCs in repairing bone defects.

Relationship between chromosome behaviour and stability of human-mouse and human-(human-mouse)hvbridomas

Chromosomes in human-mouse and human-(human-mouse)hybridomas wereanalysed by G-banding methods.It was found that most human chromosomes,exceptNo.13 and X,Y,were retained.The frequencies of chromosomes No.1,3,4,5,6,17,19,21 and 22 were higher than those of other chromosomes in each hybridoma clone.The myeloma cell lines X63-Ag8.653 and SHM-D33 were also analysed.The morphologyof marker chromosomes was apparently different between hybridomas.There were 7 kindsof marker chromosomes in human-mouse hybridomas and 16 kinds of markerchromosomes in human-(human-mouse)hybridomas.Clones that retained humanchromosome No.1 were more stable and clones that did not retain human chromosomeNo.14 were still capable of secreting human immunoglobulin.Clones that retained humanchromosome No.2 did not secret human k light chain McAb while clones that retainedhuman chromosomes No.2 and No.22 only secreted λ light chain.

Auto-measuring System of 3-Dimensional Human Body

To realize the automation of fashion industry measuring,designing and manufacturing, the auto-measurement of 3D size of human body is of great importance. The auto measurement system of 3D human body based on Charge Coupled Devices (CCD) and infrared sensors is presented in this paper. The system can measure the bare size of human body that excludes the effect of clothing quickly and accurately.

Effects on Cell Viability and on Apoptosis in Tumoral(MCF-7)and in Normal(MCF10A)Epithelial Breast Cells after Human Chorionic Gonadotropin and Derivated-Angiotensin Peptides Treatments

Angiotensin-(1 - 7) [Ang-(1 - 7)] is an endogenous heptapeptide hormone of the renin-angiotensin system that has antiproliferative properties. The aim of this work was to evaluate the anti-proliferative and pro-apoptotic properties of Ang-(1 - 7) and of Ang-(1 - 7)-substituents 9-fluorenylmethyloxycarbonyl (Fmoc) e Ang II-derivatives containing the TOAC (2,2,6,6-tetramethylpiperidine-N-oxyl-4-amino-4-carboxylic acid) in normal (MCF10A) and in tumoral (MCF7) epithelial mammary cell lines. Both cell lines received an hCG and angiotensin peptides 24-hour treatment, in combination or alone followed by cell viability, apoptosis and cell cycle assays performed by flow cytometer (GUAVA). After hCG, Ang-(1 - 7), hCG + Ang-(1 - 7) and hCG + Ang-(1 - 7)-Fmoc treatments, MCF7 displayed cell viability decrease and mid-apoptosis increase. We also observed cell viability decrease in MCF10A after Ang-(1 - 7), Ang-(1 - 7) Fmoc and hCG + AngII Toac treatments. These cells had an increase in late apoptosis and necrosis after AngII Toac, hCG + Ang-(1 - 7) and hCG + Ang-(1 - 7)-Fmoc treatments. Regarding the cell cycle analysis, we did not observed any changes in cell cycle phases. In summary, cell viability was decreased and apoptosis (initial, mid and late) was increased after hCG and/or Ang-(1 - 7) peptides treatments. These results point out hCG and Ang-(1 - 7) as effective compounds to inhibit cell proliferation, since they decrease cell viability and increase apoptosis in both normal and in tumoral breast cells, being the effect more pronounced in the tumoral cell line. Our results support the idea of investigating more closely the putative use of these compounds as novel therapeutic agents for breast cancer.

CHEMOSENSITIVITY OF MGc80-3 HUMAN GASTRIC ADENOCARCINOMA CELLS AND ITS CLINICAL SIGNIFICANCE

In the present study, the chemosensitivity of MGc80-3 human gastric adenocarcinoma cells was determined by means of colony-forming assay and the in vitro activities of 10 anticancer drugs were examined on the basis of the clinically achievable peak plasma drug concentration. The results showed that MGc80-3 cells were most sensitive to mitomyc'n C, adriamycin and 5-fluorouracil, being consistent with the response noted in clinical gastric cancer. This cell line may retain its original drug sensitivity and may be useful in screening for new compounds with activity against this disease.

Effects of 4-(3-Chloro-Benzyl)-6,7-Dimethoxy-Quinazoline on Kinetics of P120-Catenin and Periplakin in Human Buccal Mucosa Squamous Carcinoma Cell Line

In order to detect molecular markers for the epidermal growth factor inhibitor 4-(3-chloro-benzyl)- 6,7-dimethoxy-quinazoline (tyrphostin), we investigated the kinetics of p120-catenin and periplakin in the human buccal mucosa squamous cancer cell line BICR 10 treated with 3 nM tyrphostin. Growth of BICR 10 cells was inhibited by treatment with tyrphostin. Although changes were not observed in the expression of EGFR and p120-catenin, expression of Akt, Src and periplakin in BICR 10 treated with 3 nM tyrphostin tended to decrease. In addition, phosphorylation of EGFR, Akt and Src was inhibited by treatment with tyrphostin. On immunocytochemical staining, immunoreactions with phosphorylated EGFR, phosphorylated Akt and phosphorylated p120-catenin were weak in BICR 10 treated with tyrphostin. There was a slight immunocy to chemical reaction to periplakin in BICR 10 cells induced by tyrphostin. In conclusion, the decrease in phosphorylation in EGFR and p120-catenin by tyrphostin, following the decrease in Src or Akt phosphorylation, may inhibit expression of several growth factors associated with the proliferation and migration of cancer cells.

S4B-4 A Novel Allosteric Phosphodiesterase 4D Inhibitor BPN14770 Reverses Cognitive Impairment in Humanized PDE4D Mice

Classical inhibitors of PDE4 lack subtype selectivity due to exact amino acid sequence conservation of the catalytic site,and consequently,development of these drugs has stalled due to dose-limiting side effects of nausea and emesis.While use of subtype-selective inhibitors(i.e.,for PDE4A,B,or D)could overcome this issue,conservation of the catalytic region,to which classical inhibitors bind,limits this approach.The present study examined the effects of BPN14770,an allosteric inhibitor of PDE4D,which binds to a primate-specific,N-terminal region,conferring greater than 260-fold selectivity for PDE4D.BPN14770 was 100-fold more potent for improving memory and cognition in humanized PDE4D(hPDE4D)mice,which expressed the primate-specific binding sequence,compared to wild-type mice;meanwhile,it exhibited low potency in a mouse surrogate model for emesis.The behavioral and matching neurochemical data presented established a relationship between PDE4D target engagement and effects on cognition for BPN14770.Furthermore,BPN14770 reversed memory and cognitive deficits induced byβ-amyloid peptide 1-42(Aβ42)in Morris water maze,Y maze and novel object recognition tests in the humanized PDE4D mice.The morphological analyses suggested that the number of dendrites and the dendritic length in the CA1 of hippocampus were significantly increased after the Aβ42-treated hPDE4D mice were administered of BPN14770 for two weeks.The neurochemical and molecular biological assays suggested that neuroplasticity-related proteins and neurotrophic factor BDNF in the hippocampus of hPDE4D mice were significantly increased after the hPDE4D mice were treated with BPN14770.These findings suggest clinical potential for PDE4D selective inhibitors in disorders with cognitive deficits such as Alzheimer’s disease,which affects approximately 20 million people worldwide and nearly 5 million people in the United States.

Anti-tumor effects induced by gene vaccines co-expressing truncated human prostate specific membrane antigen gene and mouse 4-1BBL

Objective To investigate the influence of m4-1BBL on anti-tumor effects induced by truncated human prostate specific membrane antigen ( tPSMA ) gene in mice. Methods A eukaryotic expression plasmid encoding tPSMA and m4-1BBL ( pDC316-tPSMA-IRES m4-1BBL) ,pDC316-tPSMA and pDC316 were constructed.

MALDI-TOF-MS法对重组人内皮抑素蛋白分子质量测定

肿瘤的生长依赖于血管的生成,新生血管不仅为肿瘤生长提供必需的营养物质,而且为肿瘤细胞扩散提供了重要的途径[1].1997年哈佛大学的O'Reilly等[2]发现了一种内源性新血管生成抑制因子内皮抑素(Endostatin),显示出特异抑制激活的血管内皮细胞增殖和肿瘤新血管生成的生物学活性,其抗肿瘤作用具有高效、低毒、无耐药性的优点.……

人类软骨糖蛋白-39水平与颈动脉粥样硬化斑块及其稳定性的临床观察

目的研究人类软骨糖蛋白-39(YKL-40)水平与颈动脉粥样硬化性斑块稳定性间的联系。方法回顾性分析保定市高阳县医院2011年12月至2012年12月收治的65例急性脑梗死患者的临床资料。根据患者CT或MRI诊断结果分为无斑块组(n=14)、稳定斑块组(n=21)和不稳定斑块组(n=30),并选取30例健康体检者作为健康对照组。对各组YKL-40水平进行测定,并进行统计学分析。结果急性脑梗死患者YKL-40水平远远高于健康对照组,差异有统计学意义(P<0.01);脑梗死患者中不稳定斑块组YKL-40水平远远高于稳定斑块组,稳定斑块组YKL-40水平远远高于无斑块组,差异均有统计学意义(P<0.01)。结论脑梗死患者YKL-40水平能表征患者颈动脉粥样硬化的斑块及其稳定性。

酵母双杂交技术筛选宫颈癌HeLa细胞cDNA文库中FAM92A1-289关联蛋白

目的应用酵母双杂交技术从宫颈癌He La细胞c DNA文库中筛选FAM92A1-289关联蛋白。方法构建酵母双杂交p GBKT7-FAM92A1-289诱饵载体,转化至酵母AH109感受态细胞中。利用Clontech GAL4酵母双杂交系统筛选He La细胞c DNA文库中与FAM92A1-289相互作用的蛋白质,用营养缺陷型培养基和X-a-Gal双重筛选实验进行筛选,对筛选结果进行生物信息学分析,对克隆重复率较高的蛋白进行回转验证,将β-半乳糖苷酶活性阳性的克隆进行测序并分析。结果成功构建酵母双杂交p GBKT7-FAM92A1-289诱饵载体,可在酵母细胞中正常表达FAM92A1-289,且对酵母细胞无毒性,不存在自激活现象。筛选出在SD/-Ade/-His/-Leu/-Trp四缺培养基及含X-a-Gal的SD/-Ade/-His/-Leu/-Trp四缺培养基上均能生长且β-半乳糖苷酶活性阳性的克隆9个。经生物信息学分析发现4种蛋白重复率较高,即增殖细胞核抗原(PCNA)、半乳糖凝集素1(Galectin-1)、内质网高尔基体中间室标记物53(ERGIC-53)、重组人BCL2相关永生基因1(BAG1),并均与FAM92A1-289存在相互作用。结论利用酵母双杂交技术在Hela细胞c DNA文库中成功筛选出与FAM92A1-289相互作用的蛋白,为进一步研究FAM92A1-289的功能提供了新线索。

重组人粒细胞-巨噬细胞集落刺激因子的研究进展综述

重组人粒细胞-巨噬细胞集落刺激因子（Recombinant human granulocyte macrophagecolony stimulating factor，rhGM—CSF）能刺激多谱系造血细胞的增殖和分化。除刺激粒细胞巨噬细胞外，还能刺激嗜伊红前体细胞的增殖和分化。GM—CSF主要用于治疗放、化疗及骨髓移植后的白细胞减少症，以及用于再生障碍性贫血、AIDS病和某些存在白细胞低下的免疫缺陷性疾病的治疗等。

Diagnostic value of endothelial markers and HHV-8 staining in gastrointestinal Kaposi sarcoma and its difference in endoscopic tumor staging

AIM: To clarify the diagnostic values of hematoxylin and eosin (HE), D2-40, CD31, CD34, and HHV-8 immunohistochemical (IHC) staining in gastrointestinal Kaposi's sarcoma (GI-KS) in relation to endoscopic tumor staging. METHODS: Biopsy samples (n = 133) from 41 human immunodeficiency virus-infected patients were reviewed. GI-KS was defined as histologically negative for other GI diseases and as a positive clinical response to KS therapy. The receiver operating characteristic area under the curve (ROC-AUC) was compared in relation to lesion size, GI location, and macroscopic appearances on endoscopy. RESULTS: GI-KS was confirmed in 84 lesions (81.6%). Other endoscopic findings were polyps (n = 9), inflammation (n = 4), malignant lymphoma (n = 4), and condyloma (n = 2), which mimicked GI-KS on endoscopy. ROC-AUC of HE, D2-40, blood vessel markers, and HHV-8 showed results of 0.83, 0.89, 0.80, and 0.82, respectively. For IHC staining, the ROC-AUC of D2-40 was significantly higher (P < 0.05) than that of HE staining only. In the analysis of endoscopic appearance, the ROC-AUC of HE and IHC showed a tendency toward an increase in tumor staging (e.g. , small to large, patches, and polypoid to SMT appearance). D2-40 was significantly (P < 0.05) advantageous in the upper GI tract and for polypoid appearance compared with HE staining. CONCLUSION: The diagnostic value of endothelial markers and HHV-8 staining was found to be high, and its accuracy tended to increase with endoscopic tumor staging. D2-40 will be useful for complementing HE staining in the diagnosis of GI-KS, especially in the upper GI tract and for polypoid appearance.

Ang-(1-7)exerts anti-inflammatory and antioxidant activities on high glucose-induced injury by prohibiting NF-κB-IL-1βand activating HO-1 pathways in HUVECs

Previous reports have suggested that Ang-(1-7)may have a protective effect in endothelial cells against high glucose(HG)-induced cell injury thanks to a modulatory mechanism in the NF-κB signaling pathway.In this study,we have examined whether NF-κB-IL-1βand Heme oxygenase-1(HO-1)pathways contribute to the protection of Ang-(1-7)against hyperglycemia-induced inflammation and oxidative stress in human umbilical vein endothelial cells(HUVECs).Our results indicate that time-varying exposures of HUVECs,from 1 h to 24 h,to high glucose concentrations result in an increased expression of phosphorylated(p)-p65 and HO-1 in a time-dependent manner.As an inhibitor of NF-κB,pyrrolidinedithiocarbamic acid(PDTC)suppressed IL-1βproduction induced by HG.Of note,HUVECs previously treated with Ang-(1-7)(2μM)for 30 min before being exposed to HG concentrations significantly ameliorated the HG-increased in p-p65 and IL-1βexpression;whereas obviously up-regulated the level of HO-1,along with inhibition of oxidative stress,inflammation,and the HG-induced cytotoxicity.Importantly,when HUVECs were previously treated either with PDTC or IL-1Ra for 30 min before being exposed to HG,it significantly prevented damages caused by high glucose concentrations mentioned above,while the treatment of HO-1 inhibitor Sn-protoporphyrin(SnPP)before exposure to both HG and Ang-(1-7)significantly blocked the protective effect exerted by Ang-(1-7)on endothelial cells against injuries induced by HG mentioned above.To conclude,the data of this study showed that activation and inhibition of the NF-κB-IL-1βpathway and HO-1 pathway may constitute an important defense mechanism against endothelial cell damage caused by HG concentrations.We additionally gave new evidence showing that exogenous Ang-(1-7)exerts a protective effect on HUVECs against the HG-induced cell injury via the inhibition and the activation of the NF-κB-IL-1βpathway and the HO-1 pathway,respectively.

Cyclic Changes of Lymphatic Vessels in Human Endometrium

Objective: The presence of lymphatic vessels in endometrium has been controversial and recent immunocytochemical studies with routinely paraffin embedded sections revealed lymphatic vessels in basalis and occasionally in functionalis. We aimed to investigate endometrial lymphatic vessels by immunocytochemical staining using cryosections, which provided better and consistent immunostaining for lymphatic vessels with a lymphatic marker, D2-40. We aimed further to explore the structure-function relationship of lymphatic vessels in the menstrual cycle. Materials and Methods: Sixteen cases of endometrium from menstrual, early-proliferative to latesecretary phase were immunostained for D2-40 and lymphatic vessels were morphometrically analyzed for functionalis, basalis and myometrium, respectively. Results: Lymphatic vessels were consistently most numerous in myometrium, followed by basalis in all phases whereas menstrual endometrium showed small, fragmented aggregates of lymphatic vessels in thin basalis. Earlyto mid-secretary endometrium revealed many lymphatic vessels in basalis and lower-functionalis with few lymphatic vessels in upper-functionalis. Late-secretary endometrium revealed more lymphatic vessels in upper-functionalis with dilated walls, which then burst at the surface of functionalis. Conclusions: These degenerating lymphatic vessels with markedly dilated lumen in upper-functionalis may contribute to lymphatic leakage in late-secretary phase. These immunostained lymphatic vessels in functionalis support proliferating and degenerating lymphatic vessel cycle synchronized with the menstrual cycle of endometrial arteries to maintain adequate fluid leakage.