Up to a quarter of polyps and adenomas are missed during colonoscopy due to poor visualization behind folds and the inner curves of flexures,and the presence of flat lesions that are difficult to detect.These numbers ...Up to a quarter of polyps and adenomas are missed during colonoscopy due to poor visualization behind folds and the inner curves of flexures,and the presence of flat lesions that are difficult to detect.These numbers may however be conservative because they mainly come from back-to-back studies performed with standard colonoscopes,which are unable to visualize the entire mucosal surface.In the past several years,new endoscopic techniques have been introduced to improve the detection of polyps and adenomas.The introduction of high definition colonoscopes and visual image enhancement technologies have been suggested to lead to better recognition of flat and small lesions,but the absolute increase in diagnostic yield seems limited.Cap assisted colonoscopy and water-exchange colonoscopy are methods to facilitate cecal intubation and increase patients comfort,but show only a marginal or no benefit on polyp and adenoma detection.Retroflexion is routinely used in the rectum for the inspection of the dentate line,but withdrawal in retroflexion in the colon is in general not recommended due to the risk of perforation.In contrast,colonoscopy with the Third-Eye Retroscope?may result in considerable lower miss rates compared to standard colonoscopy,but this technique is not practical in case of polypectomy and is more time consuming.The recently introduced Full Spectrum Endoscopy?colonoscopes maintains the technical capabilities of standard colonoscopes and provides a much wider view of 330 degrees compared to the 170 degrees with standard colonoscopes.Remarkable lower adenoma miss rates with this new technique were recently demonstrated in the first randomized study.Nonetheless,more studies are required to determine the exact additional diagnostic yield in clinical practice.Optimizing the efficacy of colorectal cancer screening and surveillance requires high definition colonoscopes with improved virtual chromoendoscopy technology that visualize the whole colon mucosa while maintaining optimal washing,suction and therapeutic capabilities,and keeping the procedural time as low and patient discomfort as optimal as possible.展开更多
A color based system using multiple templates was developed and implemented for detecting hu-man faces in color images.The algorithm comsists of three image processing steps.The first step is human skin color statisti...A color based system using multiple templates was developed and implemented for detecting hu-man faces in color images.The algorithm comsists of three image processing steps.The first step is human skin color statistics.Then it separates skin regions from non-skin regions.After that,it locates the frontal human face(s) within the skin regions.In the first step,250 skin samples from persons of different ethnicities are used to determine the color distribution of human skin in chromatic color space in order to get a chroma chart showing likelihoods of skin colors.This chroma chart is used to generate,from the original color image,a gray scale image whose gray value at a pixel shows its likelihood of representing the shin,The algorithm uses an adaptive thresholding process to achieve the optimal threshold value for dividing the gray scale image into sep-arate skin regions from non skin regions.Finally,multiple face templates matching is used to determine if a given skin region represents a frontal human face or not.Test of the system with more than 400 color images showed that the resulting detection rate was 83%,which is better than most colou-based face detection sys-tems.The average speed for face detection is 0.8 second/image(400×300pixels) on a Pentium 3(800MHz) PC.展开更多
Banana bunchy top virus disease (BBTD) is a disastrous disease in bananas, and it is spreading in the world (including China) by the banana bunchy top virus(BBTV). At present, virus\|free plantlets are used to prevent...Banana bunchy top virus disease (BBTD) is a disastrous disease in bananas, and it is spreading in the world (including China) by the banana bunchy top virus(BBTV). At present, virus\|free plantlets are used to prevent BBTD in banana production, therefore, it is very important to establish a method to detect BBTV quickly, sensitively and specifically. ELISA is now popularly used to detect BBTV. The sensitivity of this method is not high enough, and needs specific antiserum, otherwise, pseudo\|positive results often occur. According to DNA coding sequences of component Ⅲ,Ⅳ and Ⅰ of BBTV isolates from Zhangzhou, China, three pairs of primers are designed to establish a PCR method to specifically amplify parts of coding sequences of the BBTV coat protein, movement protein and replicase\|association. This method is also applicable to detect BBTV of bananas or cultured banana seedlings in other regions.展开更多
Despite a decline in the overall incidence of gastric cancer(GC),the disease remains the second most common cause of cancer-related death worldwide and is thus a significant global health problem.The best means of imp...Despite a decline in the overall incidence of gastric cancer(GC),the disease remains the second most common cause of cancer-related death worldwide and is thus a significant global health problem.The best means of improving the survival of GC patients is to screen for and treat early lesions.However,GC is often diagnosed at an advanced stage and is associated with a poor prognosis.Current diagnostic and therapeutic strategies have not been successful in decreasing the global burden of the disease;therefore,the identification of reliable biomarkers for an early diagnosis,predictive markers of recurrence and survival and markers of drug sensitivity and/or resistance is urgently needed.The initiation and progression of GC depends not only on genetic alterations but also epigenetic changes,such as DNA methylation and histone modification.Aberrant DNA methylation is the most well-defined epigenetic change in human cancers and is associated with inappropriate gene silencing.Therefore,an increasing number of genes methylated at the promoter region have been targeted as possible biomarkers for different purposes,including early detection,classification,the assessment of the tumor prognosis,the development of therapeutic strategies and patient follow-up.This review article summarizes the current understanding and recent evidence regarding DNA methylation markers in GC with a focus on the clinical potential of these markers.展开更多
文摘Up to a quarter of polyps and adenomas are missed during colonoscopy due to poor visualization behind folds and the inner curves of flexures,and the presence of flat lesions that are difficult to detect.These numbers may however be conservative because they mainly come from back-to-back studies performed with standard colonoscopes,which are unable to visualize the entire mucosal surface.In the past several years,new endoscopic techniques have been introduced to improve the detection of polyps and adenomas.The introduction of high definition colonoscopes and visual image enhancement technologies have been suggested to lead to better recognition of flat and small lesions,but the absolute increase in diagnostic yield seems limited.Cap assisted colonoscopy and water-exchange colonoscopy are methods to facilitate cecal intubation and increase patients comfort,but show only a marginal or no benefit on polyp and adenoma detection.Retroflexion is routinely used in the rectum for the inspection of the dentate line,but withdrawal in retroflexion in the colon is in general not recommended due to the risk of perforation.In contrast,colonoscopy with the Third-Eye Retroscope?may result in considerable lower miss rates compared to standard colonoscopy,but this technique is not practical in case of polypectomy and is more time consuming.The recently introduced Full Spectrum Endoscopy?colonoscopes maintains the technical capabilities of standard colonoscopes and provides a much wider view of 330 degrees compared to the 170 degrees with standard colonoscopes.Remarkable lower adenoma miss rates with this new technique were recently demonstrated in the first randomized study.Nonetheless,more studies are required to determine the exact additional diagnostic yield in clinical practice.Optimizing the efficacy of colorectal cancer screening and surveillance requires high definition colonoscopes with improved virtual chromoendoscopy technology that visualize the whole colon mucosa while maintaining optimal washing,suction and therapeutic capabilities,and keeping the procedural time as low and patient discomfort as optimal as possible.
文摘A color based system using multiple templates was developed and implemented for detecting hu-man faces in color images.The algorithm comsists of three image processing steps.The first step is human skin color statistics.Then it separates skin regions from non-skin regions.After that,it locates the frontal human face(s) within the skin regions.In the first step,250 skin samples from persons of different ethnicities are used to determine the color distribution of human skin in chromatic color space in order to get a chroma chart showing likelihoods of skin colors.This chroma chart is used to generate,from the original color image,a gray scale image whose gray value at a pixel shows its likelihood of representing the shin,The algorithm uses an adaptive thresholding process to achieve the optimal threshold value for dividing the gray scale image into sep-arate skin regions from non skin regions.Finally,multiple face templates matching is used to determine if a given skin region represents a frontal human face or not.Test of the system with more than 400 color images showed that the resulting detection rate was 83%,which is better than most colou-based face detection sys-tems.The average speed for face detection is 0.8 second/image(400×300pixels) on a Pentium 3(800MHz) PC.
文摘Banana bunchy top virus disease (BBTD) is a disastrous disease in bananas, and it is spreading in the world (including China) by the banana bunchy top virus(BBTV). At present, virus\|free plantlets are used to prevent BBTD in banana production, therefore, it is very important to establish a method to detect BBTV quickly, sensitively and specifically. ELISA is now popularly used to detect BBTV. The sensitivity of this method is not high enough, and needs specific antiserum, otherwise, pseudo\|positive results often occur. According to DNA coding sequences of component Ⅲ,Ⅳ and Ⅰ of BBTV isolates from Zhangzhou, China, three pairs of primers are designed to establish a PCR method to specifically amplify parts of coding sequences of the BBTV coat protein, movement protein and replicase\|association. This method is also applicable to detect BBTV of bananas or cultured banana seedlings in other regions.
文摘Despite a decline in the overall incidence of gastric cancer(GC),the disease remains the second most common cause of cancer-related death worldwide and is thus a significant global health problem.The best means of improving the survival of GC patients is to screen for and treat early lesions.However,GC is often diagnosed at an advanced stage and is associated with a poor prognosis.Current diagnostic and therapeutic strategies have not been successful in decreasing the global burden of the disease;therefore,the identification of reliable biomarkers for an early diagnosis,predictive markers of recurrence and survival and markers of drug sensitivity and/or resistance is urgently needed.The initiation and progression of GC depends not only on genetic alterations but also epigenetic changes,such as DNA methylation and histone modification.Aberrant DNA methylation is the most well-defined epigenetic change in human cancers and is associated with inappropriate gene silencing.Therefore,an increasing number of genes methylated at the promoter region have been targeted as possible biomarkers for different purposes,including early detection,classification,the assessment of the tumor prognosis,the development of therapeutic strategies and patient follow-up.This review article summarizes the current understanding and recent evidence regarding DNA methylation markers in GC with a focus on the clinical potential of these markers.
