Axonal remodeling is a critical aspect of ischemic brain repair processes and contributes to spontaneous functional recovery.Our previous in vitro study demonstrated that exosomes/small extracellular vesicles(sEVs)iso...Axonal remodeling is a critical aspect of ischemic brain repair processes and contributes to spontaneous functional recovery.Our previous in vitro study demonstrated that exosomes/small extracellular vesicles(sEVs)isolated from cerebral endothelial cells(CEC-sEVs)of ischemic brain promote axonal growth of embryonic cortical neurons and that microRNA 27a(miR-27a)is an elevated miRNA in ischemic CEC-sEVs.In the present study,we investigated whether normal CEC-sEVs engineered to enrich their levels of miR-27a(27a-sEVs)further enhance axonal growth and improve neurological outcomes after ischemic stroke when compared with treatment with non-engineered CEC-sEVs.27a-sEVs were isolated from the conditioned medium of healthy mouse CECs transfected with a lentiviral miR-27a expression vector.Small EVs isolated from CECs transfected with a scramble vector(Scra-sEVs)were used as a control.Adult male mice were subjected to permanent middle cerebral artery occlusion and then were randomly treated with 27a-sEVs or Scra-sEVs.An array of behavior assays was used to measure neurological function.Compared with treatment of ischemic stroke with Scra-sEVs,treatment with 27a-sEVs significantly augmented axons and spines in the peri-infarct zone and in the corticospinal tract of the spinal grey matter of the denervated side,and significantly improved neurological outcomes.In vitro studies demonstrated that CEC-sEVs carrying reduced miR-27a abolished 27a-sEV-augmented axonal growth.Ultrastructural analysis revealed that 27a-sEVs systemically administered preferentially localized to the pre-synaptic active zone,while quantitative reverse transcription-polymerase chain reaction and Western Blot analysis showed elevated miR-27a,and reduced axonal inhibitory proteins Semaphorin 6A and Ras Homolog Family Member A in the peri-infarct zone.Blockage of the Clathrin-dependent endocytosis pathway substantially reduced neuronal internalization of 27a-sEVs.Our data provide evidence that 27a-sEVs have a therapeutic effect on stroke recovery by promoting axonal remodeling and improving neurological outcomes.Our findings also suggest that suppression of axonal inhibitory proteins such as Semaphorin 6A may contribute to the beneficial effect of 27a-sEVs on axonal remodeling.展开更多
The field of gastroenterology has experienced revolutionary advances over the past years,as flexible endoscopes have become widely accessible.In addition to enabling faster,less invasive,and more affordable treatment,...The field of gastroenterology has experienced revolutionary advances over the past years,as flexible endoscopes have become widely accessible.In addition to enabling faster,less invasive,and more affordable treatment,flexible endoscopes have greatly improved the detection and endoscopic screening of malignancies and prevented many cancer-related deaths.The development and clinical application of new diagnostic endoscopic technologies,such as magnification endoscopy,narrow-band imaging,endoscopic ultrasound with biopsy,and more recently,artificial intelligence enhanced technologies,have made the recognition and detection of various neoplasms and sub-epithelial tumors more possible.This review demonstrates the latest advancements in endoscopic procedures,techniques,and devices applied in the diagnosis and management of gastrointestinal cancer.展开更多
This review focuses on the diagnostic algorithm for nonobstructive azoospermia(NOA),a significant male factor contributing to infertility.NOA,characterized by the absence of sperm in the ejaculate,requires a systemati...This review focuses on the diagnostic algorithm for nonobstructive azoospermia(NOA),a significant male factor contributing to infertility.NOA,characterized by the absence of sperm in the ejaculate,requires a systematic diagnostic approach to identify reversible conditions,genetic factors,and prognosis for achieving pregnancy.The diagnostic pathway involves semen analysis and a comprehensive evaluation for hormonal deficiencies,anatomical abnormalities,and genetic factors.The importance of medical history,physical examination,endocrine evaluation,imaging,and genetic testing is emphasized.This review highlights the significance of differentiating NOA from obstructive azoospermia(OA)and outlines key considerations for effective management,including surgical sperm retrieval and assisted reproductive techniques.Testicular biopsy is discussed as a definitive method to distinguish obstructive cases from nonobstructive cases,providing valuable prognostic information.Overall,a thorough and systematic diagnostic approach is essential for the effective management of men suspected with NOA,offering insights into potential treatment options and reproductive outcomes.展开更多
某SUV在粗糙路面行驶存在低频耳压感噪声问题。通过LMS Test.lab软件采集噪声及振动试验数据分析,确认是22~24 Hz低频噪声问题。通过激励源-路径试验调查分析方法分析出该低频耳压感噪声问题由车身顶盖局部模态频率与路面激励频率耦合...某SUV在粗糙路面行驶存在低频耳压感噪声问题。通过LMS Test.lab软件采集噪声及振动试验数据分析,确认是22~24 Hz低频噪声问题。通过激励源-路径试验调查分析方法分析出该低频耳压感噪声问题由车身顶盖局部模态频率与路面激励频率耦合产生。结合试验调试和CAE Trim Body NTF仿真分析优化方法,提出了在车身顶盖与横梁间增加橡胶块的噪声优化方案,通过整车试验验证了该方案可优化低频噪声10 dBA左右。通过整车试验研究橡胶块方案的刚度、数量及布置位置等对22~24 Hz噪声的影响,在保证噪声优化效果的同时,进一步简化了橡胶块优化方案。该文为车身相关低频路噪问题提出了一种新的解决方法。展开更多
Crohn’s disease(CD)is an idiopathic,chronic,and recurrent inflammatory condition of the gastrointestinal tract.Recent studies suggest a potential role of gut microbiota in CD,particularly dysbiosis—an imbalance in g...Crohn’s disease(CD)is an idiopathic,chronic,and recurrent inflammatory condition of the gastrointestinal tract.Recent studies suggest a potential role of gut microbiota in CD,particularly dysbiosis—an imbalance in gut bacteria.While dysbiosis is consistently observed in CD,it remains uncertain whether it is a cause or a consequence of the disease.Given its association with CD,the therapeutic potential of fecal microbiota transplantation(FMT)has been explored.This review examines the role of gut microbiota in CD,evaluates the therapeutic potential of probiotics and FMT,and highlights current research findings and limitations.Key studies on the relationship between gut dysbiosis,probiotics,and FMT in CD were analyzed,with a focus on randomized trials,meta-analyses,and clinical observations.Dysbiosis is a consistent feature of CD,but its causative role remains unclear.Probiotics,prebiotics,and synbiotics have shown no efficacy in inducing or maintaining remission in CD.FMT shows potential as a therapeutic option for CD,but its efficacy remains inconsistent and inconclusive.The variability in outcomes,including diminished effects over time despite repeated FMT,underscores the need for larger,well-controlled trials.Only one randomized controlled trial(RCT)has compared FMT with sham transplantation,but the sample size was very small.Other studies are limited by factors such as small sample sizes,lack of control groups,short follow-up periods,and inconsistent methodologies,making it challenging to draw definitive conclusions.While gut dysbiosis likely plays a role in CD pathogenesis,its causative role remains uncertain.Current evidence does not support FMT as a reliable treatment for inducing or maintaining remission in CD,though it appears generally safe.Larger,standardized,RCTs are necessary to clarify the therapeutic role of FMT in CD management.展开更多
BACKGROUND Colorectal cancer(CRC)can be prevented by screening and early detection.Colonoscopy is used for screening,and adenoma detection rate(ADR)is used as a key quality indicator of sufficient colonoscopy.However,...BACKGROUND Colorectal cancer(CRC)can be prevented by screening and early detection.Colonoscopy is used for screening,and adenoma detection rate(ADR)is used as a key quality indicator of sufficient colonoscopy.However,ADR can vary significantly among endoscopists,leading to missed polyps or cancer.Artificial intelligence(AI)has shown promise in improving ADR by assisting in real-time polyp identification or diagnosis.While multiple randomized controlled trials(RCTs)and metanalyses highlight the benefits of AI in increasing detection rates and reducing missed polyps,concerns remain about its real-world applicability,impact on procedure time,and cost-effectiveness.AIM To explore the current status of AI assistance colonoscopy in adenoma detection and improving quality of colonoscopy.METHODS This systematic review followed PRISMA guidelines,both PubMed and Web of Science databases were used for articles search.Metanalyses and systematic reviews that assessed AI's role during colonoscopy.English article only published between January 2000 and January 2025 were included.Articles related to nonadenoma indications were excluded.Data extraction was independently performed by two researchers for accuracy and consistency.RESULTS 22 articles met the inclusion criteria,with significant heterogeneity(I2=28%-91%)observed in multiple studies.The number of studies per metanalysis ranged from 5 to 33,with higher heterogeneity in analyses involving more than 18 RCTs.AI demonstrated improvement in ADR,with an approximate 20%increase across multiple studies.However,its effectiveness in detecting flat or serrated adenomas remains unproven.Endoscopists with low ADR benefit more from AI-colonoscopies,while expert endoscopists outperformed AI in ADR,adenoma miss rate,and the identification of advanced lesions.No significant change in withdrawal time was observed when comparing AI-assisted colonoscopy to conventional endoscopy.CONCLUSION While AI-assisted colonoscopy has been shown to improve procedural quality,particularly for junior endoscopists and those with lower ADR,its performance decreases when compared to expert endoscopists in real-time clinical practice.This is especially evident in non-randomized studies,where AI demonstrates limited real-world benefits despite its benefit in controlled settings.Furthermore,no meta-analyses have specifically examined AI's impact on the learning experience of fellows and residents.Some experts caution that reliance on AI may prevent trainees from developing essential observational skills,potentially leading to less thorough examinations.Further research is needed to determine the actual benefits of AI-colonoscopy,particularly its role in cancer prevention.As technology advances,improved outcomes are expected,especially in detecting small,flat,and lesions at difficult anatomical locations.展开更多
High-pressure die-cast(HPDC)magnesium(Mg)and aluminum alloys enable vehicle lightweighting while reducing manufacturing costs by simplifying part assembly.The increasing use of super-large castings in electric vehicle...High-pressure die-cast(HPDC)magnesium(Mg)and aluminum alloys enable vehicle lightweighting while reducing manufacturing costs by simplifying part assembly.The increasing use of super-large castings in electric vehicles enhances structural reliability and cost efficiency.However,HPDC Mg alloys face challenges related to casting defects such as porosity,cold shuts,and oxides.These defects influence tensile strength and ductility,depending on their location and size.This study employs finite element(FE)modeling to investigate how a dominant large pore,its position,and the sample size affect the ductility of thin-walled HPDC Mg.Motivated by the ductility variations reported in literature and the experimental findings on AM60 castings,synthetic microstructure-based models are used to assess the effects of different pore sizes and locations.The results indicate the presence of three different regions based on the large pore size and model size:1)a region dominated by the effects of the large pore,2)a plateau region dominated by pore interactions,and 3)a transient region between these two effects.A threshold distance from the sample edge (d≈0.9√D·L)is proposed,within which a large pore can significantly reduce ductility.Additionally,large pores near edges contribute to ductility variations in Mg castings.展开更多
Obstructed defecation syndrome(ODS)is a complex defecatory disorder asso-ciated with pelvic floor dysfunction.It affects approximately 50%of women over the age of 50 and significantly impacts their quality of life.The...Obstructed defecation syndrome(ODS)is a complex defecatory disorder asso-ciated with pelvic floor dysfunction.It affects approximately 50%of women over the age of 50 and significantly impacts their quality of life.The causes of ODS include structural abnormalities such as rectocele,enterocele,intussusception,and pelvic floor descent,as well as functional disorders like anismus.Accurate diagnosis is crucial for effective management due to the high risk of treatment failure associated with inaccurate findings.Various imaging modalities are used to assess pelvic floor disorders,including fluoroscopic defecography(FD),mag-netic resonance defecography(MRD),pelvic floor ultrasound(PFUS),and echode-fecography(EDF).FD is the most commonly performed test worldwide,offering high accuracy in diagnosing pelvic floor disorders.It provides dynamic visual-ization of defecation mechanics but involves radiation exposure.MRD offers ex-cellent soft tissue detail and multiplanar imaging without radiation,making it particularly useful for multicompartment disorders;however,it is associated with high procedural costs and limited availability.Both PFUS and EDF are minimally invasive and avoid radiation exposure.PFUS shows promise as a valuable screening tool that could help minimize the need for advanced imaging if findings are normal.EDF is also promising but requires specialized training and remains less widely available.This review evaluates the accuracy,advantages,and limitations of various diagnostic modalities for pelvic floor disorders,aiming to guide optimal clinical decision-making.展开更多
The clinicians remain uncertain about the ideal timing for loop ileostomy reversal following rectal resection surgery.The common practice of waiting 8-12 weeks to protect from anastomotic complication,especially in pa...The clinicians remain uncertain about the ideal timing for loop ileostomy reversal following rectal resection surgery.The common practice of waiting 8-12 weeks to protect from anastomotic complication,especially in patients who receive neoadjuvant chemoradiotherapy,would expose patients to dehydration,electrolyte disturbances,stoma related complications,and reduced quality of life.Randomized controlled trials have studied early reversal of ileostomy,with results ranging from improved outcomes in selected patients to increased morbidity when applied indiscriminately.Meta-analyses have also yielded heterogeneous findings,reflecting the need for careful patient selection.The study byÖzcan and Düzgün used retrospective methods to show that patients who underwent early closure experienced similar complication rates to those who had late closure,but early closure were associated with better quality of life.Taken together,current evidence suggests that reversal within 2-4 weeks may be safe and beneficial in meticulously selected patients with an intact anastomosis and an uneventful postoperative course.Their study provides practical data supporting early closure.It is limited,however,by being retrospective with a short follow-up period,which may leave important concerns unaddressed.Multicenter randomized trials are required to help establish safe standardized criteria for early closure and longterm safety.展开更多
Male infertility has seen an increase in prevalence with cases of azoospermia estimated to affect 10%–15%of infertile men.Confirmation of azoospermia subsequently necessitates an early causal differentiation between ...Male infertility has seen an increase in prevalence with cases of azoospermia estimated to affect 10%–15%of infertile men.Confirmation of azoospermia subsequently necessitates an early causal differentiation between obstructive azoospermia(OA)and nonobstructive azoospermia(NOA).Although less common when compared to NOA,OA can represent upward 20%–40%of cases of azoospermia.While there are a multitude of etiologies responsible for causing NOA and OA,correctly distinguishing between the two types of azoospermia has profound implications in managing the infertile male.This review represents an amalgamation of the current guidelines and literature which will supply the reproductive physician with a diagnostic armamentarium to properly distinguish between NOA and OA,therefore providing the best possible care to the infertile couple.展开更多
Azoospermia is the complete absence of spermatozoa in the ejaculate in two or more semen analyses after centrifugation.Nonobstructive azoospermia(NOA)represents the most severe form of male factor infertility accounti...Azoospermia is the complete absence of spermatozoa in the ejaculate in two or more semen analyses after centrifugation.Nonobstructive azoospermia(NOA)represents the most severe form of male factor infertility accounting for 10%–15%of cases and stems from an impairment to spermatogenesis.Understanding of the hypothalamic–pituitary–testicular axis has allowed NOA to be subcategorized by anatomic and/or pathophysiologic level.The etiologies of NOA,and therefore,the differential diagnoses when considering NOA as a cause of male factor infertility,can be subcategorized and condensed into several distinct classifications.Etiologies of NOA include primary hypogonadism,secondary hypogonadism,defects in androgen synthesis and/or response,defective spermatogenesis and sperm maturation,or a mixed picture thereof.This review includes up-to-date clinical,diagnostic,cellular,and histologic features pertaining to the multitude of NOA etiologies.This in turn will provide a framework by which physicians practicing infertility can augment their clinical decision-making,patient counseling,thereby improving upon the management of men with NOA.展开更多
基金supported by the NIH grants,R01 NS111801(to ZGZ)American Heart Association 16SDG29860003(to YZ)。
文摘Axonal remodeling is a critical aspect of ischemic brain repair processes and contributes to spontaneous functional recovery.Our previous in vitro study demonstrated that exosomes/small extracellular vesicles(sEVs)isolated from cerebral endothelial cells(CEC-sEVs)of ischemic brain promote axonal growth of embryonic cortical neurons and that microRNA 27a(miR-27a)is an elevated miRNA in ischemic CEC-sEVs.In the present study,we investigated whether normal CEC-sEVs engineered to enrich their levels of miR-27a(27a-sEVs)further enhance axonal growth and improve neurological outcomes after ischemic stroke when compared with treatment with non-engineered CEC-sEVs.27a-sEVs were isolated from the conditioned medium of healthy mouse CECs transfected with a lentiviral miR-27a expression vector.Small EVs isolated from CECs transfected with a scramble vector(Scra-sEVs)were used as a control.Adult male mice were subjected to permanent middle cerebral artery occlusion and then were randomly treated with 27a-sEVs or Scra-sEVs.An array of behavior assays was used to measure neurological function.Compared with treatment of ischemic stroke with Scra-sEVs,treatment with 27a-sEVs significantly augmented axons and spines in the peri-infarct zone and in the corticospinal tract of the spinal grey matter of the denervated side,and significantly improved neurological outcomes.In vitro studies demonstrated that CEC-sEVs carrying reduced miR-27a abolished 27a-sEV-augmented axonal growth.Ultrastructural analysis revealed that 27a-sEVs systemically administered preferentially localized to the pre-synaptic active zone,while quantitative reverse transcription-polymerase chain reaction and Western Blot analysis showed elevated miR-27a,and reduced axonal inhibitory proteins Semaphorin 6A and Ras Homolog Family Member A in the peri-infarct zone.Blockage of the Clathrin-dependent endocytosis pathway substantially reduced neuronal internalization of 27a-sEVs.Our data provide evidence that 27a-sEVs have a therapeutic effect on stroke recovery by promoting axonal remodeling and improving neurological outcomes.Our findings also suggest that suppression of axonal inhibitory proteins such as Semaphorin 6A may contribute to the beneficial effect of 27a-sEVs on axonal remodeling.
文摘The field of gastroenterology has experienced revolutionary advances over the past years,as flexible endoscopes have become widely accessible.In addition to enabling faster,less invasive,and more affordable treatment,flexible endoscopes have greatly improved the detection and endoscopic screening of malignancies and prevented many cancer-related deaths.The development and clinical application of new diagnostic endoscopic technologies,such as magnification endoscopy,narrow-band imaging,endoscopic ultrasound with biopsy,and more recently,artificial intelligence enhanced technologies,have made the recognition and detection of various neoplasms and sub-epithelial tumors more possible.This review demonstrates the latest advancements in endoscopic procedures,techniques,and devices applied in the diagnosis and management of gastrointestinal cancer.
文摘This review focuses on the diagnostic algorithm for nonobstructive azoospermia(NOA),a significant male factor contributing to infertility.NOA,characterized by the absence of sperm in the ejaculate,requires a systematic diagnostic approach to identify reversible conditions,genetic factors,and prognosis for achieving pregnancy.The diagnostic pathway involves semen analysis and a comprehensive evaluation for hormonal deficiencies,anatomical abnormalities,and genetic factors.The importance of medical history,physical examination,endocrine evaluation,imaging,and genetic testing is emphasized.This review highlights the significance of differentiating NOA from obstructive azoospermia(OA)and outlines key considerations for effective management,including surgical sperm retrieval and assisted reproductive techniques.Testicular biopsy is discussed as a definitive method to distinguish obstructive cases from nonobstructive cases,providing valuable prognostic information.Overall,a thorough and systematic diagnostic approach is essential for the effective management of men suspected with NOA,offering insights into potential treatment options and reproductive outcomes.
文摘某SUV在粗糙路面行驶存在低频耳压感噪声问题。通过LMS Test.lab软件采集噪声及振动试验数据分析,确认是22~24 Hz低频噪声问题。通过激励源-路径试验调查分析方法分析出该低频耳压感噪声问题由车身顶盖局部模态频率与路面激励频率耦合产生。结合试验调试和CAE Trim Body NTF仿真分析优化方法,提出了在车身顶盖与横梁间增加橡胶块的噪声优化方案,通过整车试验验证了该方案可优化低频噪声10 dBA左右。通过整车试验研究橡胶块方案的刚度、数量及布置位置等对22~24 Hz噪声的影响,在保证噪声优化效果的同时,进一步简化了橡胶块优化方案。该文为车身相关低频路噪问题提出了一种新的解决方法。
文摘Crohn’s disease(CD)is an idiopathic,chronic,and recurrent inflammatory condition of the gastrointestinal tract.Recent studies suggest a potential role of gut microbiota in CD,particularly dysbiosis—an imbalance in gut bacteria.While dysbiosis is consistently observed in CD,it remains uncertain whether it is a cause or a consequence of the disease.Given its association with CD,the therapeutic potential of fecal microbiota transplantation(FMT)has been explored.This review examines the role of gut microbiota in CD,evaluates the therapeutic potential of probiotics and FMT,and highlights current research findings and limitations.Key studies on the relationship between gut dysbiosis,probiotics,and FMT in CD were analyzed,with a focus on randomized trials,meta-analyses,and clinical observations.Dysbiosis is a consistent feature of CD,but its causative role remains unclear.Probiotics,prebiotics,and synbiotics have shown no efficacy in inducing or maintaining remission in CD.FMT shows potential as a therapeutic option for CD,but its efficacy remains inconsistent and inconclusive.The variability in outcomes,including diminished effects over time despite repeated FMT,underscores the need for larger,well-controlled trials.Only one randomized controlled trial(RCT)has compared FMT with sham transplantation,but the sample size was very small.Other studies are limited by factors such as small sample sizes,lack of control groups,short follow-up periods,and inconsistent methodologies,making it challenging to draw definitive conclusions.While gut dysbiosis likely plays a role in CD pathogenesis,its causative role remains uncertain.Current evidence does not support FMT as a reliable treatment for inducing or maintaining remission in CD,though it appears generally safe.Larger,standardized,RCTs are necessary to clarify the therapeutic role of FMT in CD management.
文摘BACKGROUND Colorectal cancer(CRC)can be prevented by screening and early detection.Colonoscopy is used for screening,and adenoma detection rate(ADR)is used as a key quality indicator of sufficient colonoscopy.However,ADR can vary significantly among endoscopists,leading to missed polyps or cancer.Artificial intelligence(AI)has shown promise in improving ADR by assisting in real-time polyp identification or diagnosis.While multiple randomized controlled trials(RCTs)and metanalyses highlight the benefits of AI in increasing detection rates and reducing missed polyps,concerns remain about its real-world applicability,impact on procedure time,and cost-effectiveness.AIM To explore the current status of AI assistance colonoscopy in adenoma detection and improving quality of colonoscopy.METHODS This systematic review followed PRISMA guidelines,both PubMed and Web of Science databases were used for articles search.Metanalyses and systematic reviews that assessed AI's role during colonoscopy.English article only published between January 2000 and January 2025 were included.Articles related to nonadenoma indications were excluded.Data extraction was independently performed by two researchers for accuracy and consistency.RESULTS 22 articles met the inclusion criteria,with significant heterogeneity(I2=28%-91%)observed in multiple studies.The number of studies per metanalysis ranged from 5 to 33,with higher heterogeneity in analyses involving more than 18 RCTs.AI demonstrated improvement in ADR,with an approximate 20%increase across multiple studies.However,its effectiveness in detecting flat or serrated adenomas remains unproven.Endoscopists with low ADR benefit more from AI-colonoscopies,while expert endoscopists outperformed AI in ADR,adenoma miss rate,and the identification of advanced lesions.No significant change in withdrawal time was observed when comparing AI-assisted colonoscopy to conventional endoscopy.CONCLUSION While AI-assisted colonoscopy has been shown to improve procedural quality,particularly for junior endoscopists and those with lower ADR,its performance decreases when compared to expert endoscopists in real-time clinical practice.This is especially evident in non-randomized studies,where AI demonstrates limited real-world benefits despite its benefit in controlled settings.Furthermore,no meta-analyses have specifically examined AI's impact on the learning experience of fellows and residents.Some experts caution that reliance on AI may prevent trainees from developing essential observational skills,potentially leading to less thorough examinations.Further research is needed to determine the actual benefits of AI-colonoscopy,particularly its role in cancer prevention.As technology advances,improved outcomes are expected,especially in detecting small,flat,and lesions at difficult anatomical locations.
基金funded by the Department of Energy Office of Vehicle Technologies under the Automotive Lightweighting Materials Program。
文摘High-pressure die-cast(HPDC)magnesium(Mg)and aluminum alloys enable vehicle lightweighting while reducing manufacturing costs by simplifying part assembly.The increasing use of super-large castings in electric vehicles enhances structural reliability and cost efficiency.However,HPDC Mg alloys face challenges related to casting defects such as porosity,cold shuts,and oxides.These defects influence tensile strength and ductility,depending on their location and size.This study employs finite element(FE)modeling to investigate how a dominant large pore,its position,and the sample size affect the ductility of thin-walled HPDC Mg.Motivated by the ductility variations reported in literature and the experimental findings on AM60 castings,synthetic microstructure-based models are used to assess the effects of different pore sizes and locations.The results indicate the presence of three different regions based on the large pore size and model size:1)a region dominated by the effects of the large pore,2)a plateau region dominated by pore interactions,and 3)a transient region between these two effects.A threshold distance from the sample edge (d≈0.9√D·L)is proposed,within which a large pore can significantly reduce ductility.Additionally,large pores near edges contribute to ductility variations in Mg castings.
文摘Obstructed defecation syndrome(ODS)is a complex defecatory disorder asso-ciated with pelvic floor dysfunction.It affects approximately 50%of women over the age of 50 and significantly impacts their quality of life.The causes of ODS include structural abnormalities such as rectocele,enterocele,intussusception,and pelvic floor descent,as well as functional disorders like anismus.Accurate diagnosis is crucial for effective management due to the high risk of treatment failure associated with inaccurate findings.Various imaging modalities are used to assess pelvic floor disorders,including fluoroscopic defecography(FD),mag-netic resonance defecography(MRD),pelvic floor ultrasound(PFUS),and echode-fecography(EDF).FD is the most commonly performed test worldwide,offering high accuracy in diagnosing pelvic floor disorders.It provides dynamic visual-ization of defecation mechanics but involves radiation exposure.MRD offers ex-cellent soft tissue detail and multiplanar imaging without radiation,making it particularly useful for multicompartment disorders;however,it is associated with high procedural costs and limited availability.Both PFUS and EDF are minimally invasive and avoid radiation exposure.PFUS shows promise as a valuable screening tool that could help minimize the need for advanced imaging if findings are normal.EDF is also promising but requires specialized training and remains less widely available.This review evaluates the accuracy,advantages,and limitations of various diagnostic modalities for pelvic floor disorders,aiming to guide optimal clinical decision-making.
文摘The clinicians remain uncertain about the ideal timing for loop ileostomy reversal following rectal resection surgery.The common practice of waiting 8-12 weeks to protect from anastomotic complication,especially in patients who receive neoadjuvant chemoradiotherapy,would expose patients to dehydration,electrolyte disturbances,stoma related complications,and reduced quality of life.Randomized controlled trials have studied early reversal of ileostomy,with results ranging from improved outcomes in selected patients to increased morbidity when applied indiscriminately.Meta-analyses have also yielded heterogeneous findings,reflecting the need for careful patient selection.The study byÖzcan and Düzgün used retrospective methods to show that patients who underwent early closure experienced similar complication rates to those who had late closure,but early closure were associated with better quality of life.Taken together,current evidence suggests that reversal within 2-4 weeks may be safe and beneficial in meticulously selected patients with an intact anastomosis and an uneventful postoperative course.Their study provides practical data supporting early closure.It is limited,however,by being retrospective with a short follow-up period,which may leave important concerns unaddressed.Multicenter randomized trials are required to help establish safe standardized criteria for early closure and longterm safety.
文摘Male infertility has seen an increase in prevalence with cases of azoospermia estimated to affect 10%–15%of infertile men.Confirmation of azoospermia subsequently necessitates an early causal differentiation between obstructive azoospermia(OA)and nonobstructive azoospermia(NOA).Although less common when compared to NOA,OA can represent upward 20%–40%of cases of azoospermia.While there are a multitude of etiologies responsible for causing NOA and OA,correctly distinguishing between the two types of azoospermia has profound implications in managing the infertile male.This review represents an amalgamation of the current guidelines and literature which will supply the reproductive physician with a diagnostic armamentarium to properly distinguish between NOA and OA,therefore providing the best possible care to the infertile couple.
文摘Azoospermia is the complete absence of spermatozoa in the ejaculate in two or more semen analyses after centrifugation.Nonobstructive azoospermia(NOA)represents the most severe form of male factor infertility accounting for 10%–15%of cases and stems from an impairment to spermatogenesis.Understanding of the hypothalamic–pituitary–testicular axis has allowed NOA to be subcategorized by anatomic and/or pathophysiologic level.The etiologies of NOA,and therefore,the differential diagnoses when considering NOA as a cause of male factor infertility,can be subcategorized and condensed into several distinct classifications.Etiologies of NOA include primary hypogonadism,secondary hypogonadism,defects in androgen synthesis and/or response,defective spermatogenesis and sperm maturation,or a mixed picture thereof.This review includes up-to-date clinical,diagnostic,cellular,and histologic features pertaining to the multitude of NOA etiologies.This in turn will provide a framework by which physicians practicing infertility can augment their clinical decision-making,patient counseling,thereby improving upon the management of men with NOA.
