Influencing factors for inadequate bowel preparation of colonoscopy of different colonic segments / 中华消化内镜杂志

Objective:To investigate the influencing factors for inadequate bowel preparation of colonoscopy.Methods:A total of 677 patients who underwent colonoscopy at Peking Union Medical College Hospital from December 2021 to January 2023 were recruited, and all patients underwent standardized bowel preparation by using 3 L polyglycol electrolyte powder with fractional dose. The quality of bowel preparation was assessed by Boston bowel preparation scale, and the influencing factors for inadequate bowel preparation were analyzed by logistic regression analysis.Results:The rate of inadequate bowel preparation was 31.5% (213/677). Among the patients with inadequate bowel preparation, 85.4% (182/213) inadequate bowel preparation was only in proximal colon, 14.1% (30/213) was in both proximal and distal colon, and 0.5% (1/213) was only in distal colon. Inadequate bowel preparation in distal colon and total colon were combined into inadequate bowel preparation in distal colon. The results of logistic regression analysis showed that inadequate bowel preparation in proximal colon was more likely to occur in men ( P=0.001, OR=2.253, 95% CI: 1.399-3.629), outpatients ( P<0.001, OR=4.175, 95% CI: 2.410-7.231), those with no family history of colorectal cancer ( P=0.001, OR=2.117, 95% CI: 1.365-3.284), and diagnostic colonoscopy ( P=0.003, OR=1.978, 95% CI: 1.261-3.102). And spinal disease ( P=0.044, OR=7.430, 95% CI: 1.051-52.511), outpatients ( P<0.001, OR=135.577, 95% CI: 29.135-630.883),non-compliance of dietary requirements ( P=0.006, OR=4.772, 95% CI: 1.576-14.453), adverse reaction during bowel preparation ( P=0.015, OR=4.341, 95% CI: 1.329-14.179), no family history of colorectal cancer ( P=0.003, OR=7.110, 95% CI: 1.912-26.438), and poor last stool character ( P=0.001, OR=25.922, 95% CI: 3.779-177.832) were risk factors for inadequate bowel preparation in distal colon. Conclusions:The inadequate bowel preparation of colonoscopy mainly occurs in proximal colon, and the risk factors for the inadequate bowel preparation vary in different colonic segments. Therefore, the specific interventions should be performed according to the character of different colon segments to improve the quality of bowel preparation.

Clinical Outcome of Self-Expandable Metal Stent Placement in the Management of Malignant Proximal Colon Obstruction

BACKGROUND/AIMS: There are limited data regarding the clinical outcomes of self-expandable metal stents in the treatment of proximal colon obstruction. We compared the clinical outcomes of stent placement in patients with malignant proximal to distal colon obstructions. METHODS: We reviewed medical records from 37 consecutive patients from three institutions (19 men; mean age, 72 years) who underwent endoscopic stent placement at a malignant obstruction of the proximal colon. We also examined the records from 99 patients (50 men; mean age, 65 years) who underwent endoscopic stent placement for a distal colon obstruction. Technical success, clinical improvements, complications and stent patency were compared between treatments. RESULTS: The technical success rate tended to be lower in stents inserted to treat proximal colon obstructions than in those used to treat distal colon obstructions (86% vs 97%, p=0.06). Clinical improvement was achieved in 78% of patients (29/37) with proximal colonic stenting and in 91% of patients (90/99) with distal colonic stenting (p=0.08). Complications (24% vs 27%), stent migration (8% vs 8%) and stent reocclusion rates (11% vs 17%) did not differ significantly between groups. Two cases of bowel perforation related to stenting (5%) occurred in patients with proximal colonic stenting. CONCLUSIONS: The technical success and clinical improvement associated with self-expandable metal stents used to treat proximal colon obstruction tend to be lower than cases of distal colon obstruction. Technical failure is an important cause of poor clinical improvement in patients with proximal colon stenting. Complication rates and stent patency appear to be similar in both groups.

Morphological Adaptive Responses of Gastric Parietal and Colonic Surface Epithelial Cells to Chronic Changes in Dietary Potassium / 대한해부학회지

Potassium (K+) balance is achieved by the control of urinary K+ excretion and by the control of K+ absorption from the digestive tract. It has been established that chronic potassium depletion is associated with a remarkable hypertrophy of the collecting duct of the kidney. But, there is no morphological studies regarding the stomach and distal colon during the chronic changes of potassium diet. Electron microscopy was performed to observe the morphological alterations of the stomach and distal colon in response to chronic changes of potassium diet in rat. Electron microscopy of normal parietal cells revealed the presences of many mitochondia, tubulovesicles, and short basal cytoplasmic processes and microvilli in the intracellular canaliculi. In potasium-depleted parietal cells, mito-chondria were increased in size and number, and tubulovesicles almost disappeared, and microvilli in the intracellular canaliculi were increased in number and length, and short basal cytoplasmic processes were also increased in size and number. Parietal cells of potassium-loading after restriction were found to be almost normal. Two types of surface columnar epithelial cells were present in normal distal colon. Type I cells had many mitochondria and abundant coated vesicles in the supranuclear region. Type II cells had moderate amount of mitochondria and relatively fewer coated vesicles. In comparison with normal, potasium-depleted surface columnar epithelial cells had more abundant and larger mitochondria and more numerous and longer (1.4~1.6 times than normal) microvilli. Surface columnar epithelial cells of potassium-loading after restriction were recovered almost to normal. These results suggest that gastric parietal cells and surface columnar epithelial cells of distal colon adapt through morphological changes to preserve potassium balance during chronic changes of potassium diet.

Effects of Chronic Hypokalemia on Rat Distal Colon / 대한해부학회지

Recent molecular and physiological studies suggested that at least two distinct H/K-ATPase activities are present in the mammalian colon. Potassium (K+) balance is achieved by the control of urinary K+ excretion and by the control of K+ absorption from the digestive tract. The colon also participates substantively in the regulation of systemic K+ homeostasis. Northern analysis and in situ hybridization (ISH) for analyzing the expression of mRNA encoding the colonic H/K-ATPase a subunit and EM study for morphologic adaptations were carried out in normal and potassium-deprived (2 weeks) rats. Northern analysis demonstrated that colonic H/K-ATPase a subunit mRNA is abundantly expressed in normal rat distal colon. Abundance of colonic H/K-ATPase a subunit mRNA in potassium-deprived rat distal colon was not significantly increased compared to controls. By ISH, mRNA for colonic H/K-ATPase a subunit was detected in the surface epithelial cells, Goblet cells, and upper third of the intestinal gland. Both groups exhibited comparable cellular patterns of labeling and signal intensity. The surface epithelial cells exhibited a mixture of hybridization signal intensity. Most cells had intense hybridization signal for colonic H/K-ATPase a subunit mRNA and some cells had moderate, and a few cells had weak. Occasionally, strong hybridization signal was detected in the lower portion of the intestinal gland. EM study demonstrated that two types of surface columnar epithelial cells were present in normal distal colon and included type 1 cells with more abundant vesicles in supranuclear cytoplasm and type 2 cells with moderate amount of vesicles. In potassium-deprived distal colon, type 2 cells were only present in surface columnar epithelial cells. Others were not significant differences between two groups. These results suggest that two (or more) H/K-ATPase a subunit isoforms are present in rat distal colon, and colonic H/K-ATPase asubunit gene does not significantly contribute to potassium conservation during chronic hypokalemia in spite of abundant expression of this gene.

Capacitative Ca~(2+) entry mediate contraction in rat distal colon smooth muscle / 中国药理学通报

Aim To investigate whether capacitative Ca~(2+) entry involved in excitation-contraction coupling in rat distal colon smooth muscle.Methods Changes of isolated organ's tension were monitored with force-displacement transducer and Powerlab 4/25T recording system.Results Thapsigargin(10 nmol?L~(-1)～1 ?mol?L~(-1))produced slowly developing sustained contractions in isolated distal colon smooth muscle strips of rats.The timed contractile responses to thapsigargin(10 n mol?L~(1)-1 ?mol?L~(-1)) were significantly different.The contractile response to Ca~(2+) reintroduction following incubation of strips in a Ca~(2+)-free Krebs in the presense of thapsigargin was significantly higher than in its absence(99%?28% vs 70%?8%).Contractile responses to Ca~(2+)reintroduction following depletion of sarcoplasmic reticulum Ca~(2+) stores with thapsigargin were attenuated by La~(3+),while unaffected by verapamil.Conclusion Contractile responses to Ca~(2+)reintroduction following depletion of sarcoplasmic reticulum Ca~(2+)stores with thapsigargin,are mediated by capacitative Ca~(2+)entry.The results suggested that CCE provided activator Ca~(2+)for the contraction and participated in excitation-contraction process in rat distal colon smooth muscle.