Human colonic motility is a relatively difficult topic to investigate. However, the refinement of manometric techniques in recent years enabled us to study both the proximal and distal segments of the viscus. The pres...Human colonic motility is a relatively difficult topic to investigate. However, the refinement of manometric techniques in recent years enabled us to study both the proximal and distal segments of the viscus. The present paper reviews our knowledge about normal aspects of colorectal motility in man and the abnormalities found in slow transit constipation (STC), one of the most frequent and difficult to treat subtypes of constipation. An internetbased search strategy of the Medline and Science Citation Index was performed using the keywords colon, colonic, colorectal, constipation, slow transit, motility, rectal, rectum in various combinations with the Boolean operators AND, OR and NOT. Only articles related to human studies were used, and manual cross-referencing was also performed. Most of colonic motor activity is represented by single nonpropagated contractions, rarely organized in bursts; this activity is maximal during the day, especially after waking and following meals. In addition, a specialized propagated activity with propulsive features is detectable, represented by high-and low-amplitude propagated contractions. In the severe form of constipation represented by the slow transit type, the above motor activity is completely deranged. In fact, both basal segmental activity (especially in response to meals) and propagated activity (especially that of high amplitude) are usually decreased, and this may represent a physiologic marker of this disorder. Human colonic motor activity is quite a complex issue, still only partly understood and investigated, due to anatomic and physiological difficulties. In recent years, however, some more data have been obtained, even in proximal segments. These data have helped in elucidating, although only in part, some pathophysiological mechanisms of chronic constipation, and especially of the STC subtype.展开更多
AIM: To characterize the effects of age on clinical presentations and endoscopic diagnoses and to determine outcomes after endoscopic therapy among patients aged ≥ 65 years admitted for acute upper gastrointestinal b...AIM: To characterize the effects of age on clinical presentations and endoscopic diagnoses and to determine outcomes after endoscopic therapy among patients aged ≥ 65 years admitted for acute upper gastrointestinal bleeding (UGIB) compared with those aged < 65 years. METHODS: Medical records and an endoscopy data-base of 526 consecutive patients with overt UGIB admitted during 2007-2009 were reviewed. The initial presentations and clinical course within 30 d after endoscopy were obtained. RESULTS: A total of 235 patients aged ≥ 65 years constituted the elderly population (mean age of 74.2 ± 6.7 years, 63% male). Compared to young patients, the elderly patients were more likely to present with melena (53% vs 30%, respectively; P < 0.001), have comorbidities (69% vs 54%, respectively; P < 0.001), and receive antiplatelet agents (39% vs 10%, respectively; P < 0.001). Interestingly, hemodynamic instability was observed less in this group (49% vs 68%, respectively; P < 0.001). Peptic ulcer was the leading cause of UGIB in the elderly patients, followed by varices and gastropathy. The elderly and young patients had a similar clinical course with regard to the utilization of endoscopic therapy, requirement for transfusion, duration of hospital stay, need for surgery [relative risk (RR), 0.31; 95% confidence interval (CI), 0.03-2.75; P = 0.26], rebleeding (RR, 1.44; 95% CI, 0.92-2.25; P = 0.11), and mortality (RR, 1.10; 95% CI, 0.57-2.11; P = 0.77). In Cox's regression analysis, hemodynamic instability at presentation, background of liver cirrhosis or disseminated malignancy, transfusion requirement, and development of rebleeding were significantly associated with 30-d mortality. CONCLUSION: Despite multiple comorbidities and the concomitant use of antiplatelets in the elderly patients, advanced age does not appear to influence adverse outcomes of acute UGIB after therapeutic endoscopy.展开更多
AIM： To investigate the effect of release behavior of sustained-release dosage forms of sinomenine hydrochloride （SM·HCl） on its pharmacokinetics in beagle dogs. METHODS： The in vitro release behavior of two ...AIM： To investigate the effect of release behavior of sustained-release dosage forms of sinomenine hydrochloride （SM·HCl） on its pharmacokinetics in beagle dogs. METHODS： The in vitro release behavior of two SM·HCl dosage forms, including commercial 12-h sustained-release tablets and 24-h sustained-release pellets prepared in our laboratory, was examined. The two dosage forms were orally administrated to beagle dogs, and then the in vivo SM.HCI pharmacokinetics was investigated and compared. RESULTS： The optimal SM·HCl sustained-release formulation was achieved by mixing slow- and rapidrelease pellets （9：1, w/w）. The SM·HCl release profiles of the sustained-release pellets were scarcely influenced by the pH of the dissolution medium. Release from the 12-h sustained-release tablets was markedly quicker than that from the 24-h sustained-release pellets, the cumulative release up to 12-h was 99.9% vs68.7%. From a pharmacokinetic standpoint, the 24-h SM.HCI sustainedrelease pellets had longer tmax and lower Cmax compared to the 12-h sustained-release tablets, the tmax being 2.67±0.52 h vs 9.83±0.98 h and the Cmax being 1334.45±368.76 ng/mL vs 893.12±292.55 ng/mL, respectively. However, the AUC0-tn of two SM·HCl dosage forms was comparable and both preparations were statistically bioequivalent. Furthermore, the two preparations had good correlations between SM·HCl percentage absorption in vivoand the cumulative percentage release in vitro. CONCLUSION： The in vitro release properties of the dosage forms strongly affect their pharmacokinetic behavior in vivo. Therefore, managing the in vitro release behavior of dosage forms is a promising strategy for obtaining the optimal in vivo pharmacokinetic characteristics and safe therapeutic drug concentration-time curves.展开更多
In this paper, the investigation is focused on a （3＋1）-dimensional variable-coefficient Kadomtsev- Petviashvili （vcKP） equation, which can describe the realistic nonlinear phenomena in the fluid dynamics and plas...In this paper, the investigation is focused on a （3＋1）-dimensional variable-coefficient Kadomtsev- Petviashvili （vcKP） equation, which can describe the realistic nonlinear phenomena in the fluid dynamics and plasma in three spatial dimensions. In order to study the integrability property of such an equation, the Painlevé analysis is performed on it. And then, based on the truncated Painlevé expansion, the bilinear form of the （3＋1）-dimensionaJ vcKP equation is obtained under certain coefficients constraint, and its solution in the Wronskian determinant form is constructed and verified by virtue of the Wronskian technique. Besides the Wronskian determinant solution, it is shown that the （3＋1）-dimensional vcKP equation also possesses a solution in the form of the Grammian determinant.展开更多
Based on the scaling idea of local slopes by Lopez et al. [Phys. Rev. Lett. 94 （2005） 166103], we investigate anomalous dynamic scaling of （d ＋ 1）-dimensional surface growth equations with spatially and temporall...Based on the scaling idea of local slopes by Lopez et al. [Phys. Rev. Lett. 94 （2005） 166103], we investigate anomalous dynamic scaling of （d ＋ 1）-dimensional surface growth equations with spatially and temporally correlated noise. The growth equations studied include the Kardar-Parisi-Zhang （KPZ）, Sun-Guo-Grant （SGG）, and Lai-Das Sarma-Villain （LDV） equations. The anomalous scaling exponents in both the weak- and strong-coupling regions are obtained, respectively.展开更多
文摘Human colonic motility is a relatively difficult topic to investigate. However, the refinement of manometric techniques in recent years enabled us to study both the proximal and distal segments of the viscus. The present paper reviews our knowledge about normal aspects of colorectal motility in man and the abnormalities found in slow transit constipation (STC), one of the most frequent and difficult to treat subtypes of constipation. An internetbased search strategy of the Medline and Science Citation Index was performed using the keywords colon, colonic, colorectal, constipation, slow transit, motility, rectal, rectum in various combinations with the Boolean operators AND, OR and NOT. Only articles related to human studies were used, and manual cross-referencing was also performed. Most of colonic motor activity is represented by single nonpropagated contractions, rarely organized in bursts; this activity is maximal during the day, especially after waking and following meals. In addition, a specialized propagated activity with propulsive features is detectable, represented by high-and low-amplitude propagated contractions. In the severe form of constipation represented by the slow transit type, the above motor activity is completely deranged. In fact, both basal segmental activity (especially in response to meals) and propagated activity (especially that of high amplitude) are usually decreased, and this may represent a physiologic marker of this disorder. Human colonic motor activity is quite a complex issue, still only partly understood and investigated, due to anatomic and physiological difficulties. In recent years, however, some more data have been obtained, even in proximal segments. These data have helped in elucidating, although only in part, some pathophysiological mechanisms of chronic constipation, and especially of the STC subtype.
文摘AIM: To characterize the effects of age on clinical presentations and endoscopic diagnoses and to determine outcomes after endoscopic therapy among patients aged ≥ 65 years admitted for acute upper gastrointestinal bleeding (UGIB) compared with those aged < 65 years. METHODS: Medical records and an endoscopy data-base of 526 consecutive patients with overt UGIB admitted during 2007-2009 were reviewed. The initial presentations and clinical course within 30 d after endoscopy were obtained. RESULTS: A total of 235 patients aged ≥ 65 years constituted the elderly population (mean age of 74.2 ± 6.7 years, 63% male). Compared to young patients, the elderly patients were more likely to present with melena (53% vs 30%, respectively; P < 0.001), have comorbidities (69% vs 54%, respectively; P < 0.001), and receive antiplatelet agents (39% vs 10%, respectively; P < 0.001). Interestingly, hemodynamic instability was observed less in this group (49% vs 68%, respectively; P < 0.001). Peptic ulcer was the leading cause of UGIB in the elderly patients, followed by varices and gastropathy. The elderly and young patients had a similar clinical course with regard to the utilization of endoscopic therapy, requirement for transfusion, duration of hospital stay, need for surgery [relative risk (RR), 0.31; 95% confidence interval (CI), 0.03-2.75; P = 0.26], rebleeding (RR, 1.44; 95% CI, 0.92-2.25; P = 0.11), and mortality (RR, 1.10; 95% CI, 0.57-2.11; P = 0.77). In Cox's regression analysis, hemodynamic instability at presentation, background of liver cirrhosis or disseminated malignancy, transfusion requirement, and development of rebleeding were significantly associated with 30-d mortality. CONCLUSION: Despite multiple comorbidities and the concomitant use of antiplatelets in the elderly patients, advanced age does not appear to influence adverse outcomes of acute UGIB after therapeutic endoscopy.
文摘AIM： To investigate the effect of release behavior of sustained-release dosage forms of sinomenine hydrochloride （SM·HCl） on its pharmacokinetics in beagle dogs. METHODS： The in vitro release behavior of two SM·HCl dosage forms, including commercial 12-h sustained-release tablets and 24-h sustained-release pellets prepared in our laboratory, was examined. The two dosage forms were orally administrated to beagle dogs, and then the in vivo SM.HCI pharmacokinetics was investigated and compared. RESULTS： The optimal SM·HCl sustained-release formulation was achieved by mixing slow- and rapidrelease pellets （9：1, w/w）. The SM·HCl release profiles of the sustained-release pellets were scarcely influenced by the pH of the dissolution medium. Release from the 12-h sustained-release tablets was markedly quicker than that from the 24-h sustained-release pellets, the cumulative release up to 12-h was 99.9% vs68.7%. From a pharmacokinetic standpoint, the 24-h SM.HCI sustainedrelease pellets had longer tmax and lower Cmax compared to the 12-h sustained-release tablets, the tmax being 2.67±0.52 h vs 9.83±0.98 h and the Cmax being 1334.45±368.76 ng/mL vs 893.12±292.55 ng/mL, respectively. However, the AUC0-tn of two SM·HCl dosage forms was comparable and both preparations were statistically bioequivalent. Furthermore, the two preparations had good correlations between SM·HCl percentage absorption in vivoand the cumulative percentage release in vitro. CONCLUSION： The in vitro release properties of the dosage forms strongly affect their pharmacokinetic behavior in vivo. Therefore, managing the in vitro release behavior of dosage forms is a promising strategy for obtaining the optimal in vivo pharmacokinetic characteristics and safe therapeutic drug concentration-time curves.
基金Supported by the Specialized Research Fund for the Doctoral Program of Higher Education under Grant Nos. 20060006024 and 20080013006Chinese Ministry of Education, by the National Natural Science Foundation of China under Grant No. 60772023+2 种基金by the Open Fund of the State Key Laboratory of Software Development Environment under Grant No. SKLSDE-07-001Beijing University of Aeronautics and Astronauticsby the National Basic Research Program of China (973 Program) under Grant No. 2005CB321901
文摘In this paper, the investigation is focused on a （3＋1）-dimensional variable-coefficient Kadomtsev- Petviashvili （vcKP） equation, which can describe the realistic nonlinear phenomena in the fluid dynamics and plasma in three spatial dimensions. In order to study the integrability property of such an equation, the Painlevé analysis is performed on it. And then, based on the truncated Painlevé expansion, the bilinear form of the （3＋1）-dimensionaJ vcKP equation is obtained under certain coefficients constraint, and its solution in the Wronskian determinant form is constructed and verified by virtue of the Wronskian technique. Besides the Wronskian determinant solution, it is shown that the （3＋1）-dimensional vcKP equation also possesses a solution in the form of the Grammian determinant.
基金National Natural Science Foundation of China under Grant No.10674177
文摘Based on the scaling idea of local slopes by Lopez et al. [Phys. Rev. Lett. 94 （2005） 166103], we investigate anomalous dynamic scaling of （d ＋ 1）-dimensional surface growth equations with spatially and temporally correlated noise. The growth equations studied include the Kardar-Parisi-Zhang （KPZ）, Sun-Guo-Grant （SGG）, and Lai-Das Sarma-Villain （LDV） equations. The anomalous scaling exponents in both the weak- and strong-coupling regions are obtained, respectively.
