ABSTRACT
Design space approach is applied in this study to enhance the robustness of first ethanol precipitation process of Codonopsis Radix (Dangshen) by optimizing parameters. Total flavonoid recovery, dry matter removal, and pigment removal were defined as the process critical quality attributes (CQAs). Plackett-Burman designed experiments were carried out to find the critical process parameters (CPPs). Dry matter content of concentrated extract (DMCE), mass ratio of ethanol to concentrated extract (E/C ratio) and concentration of ethanol (CEA) were identified as the CPPs. Box-Behnken designed experiments were performed to establish the quantitative models between CPPs and CQAs. Probability based design space was obtained and verified using Monte-Carlo simulation method. According to the verification results, the robustness of first ethanol precipitation process of Dangshen can be guaranteed by operating within the design space parameters. Recommended normal operation space are as follows: dry matter content of concentrated extract of 45.0% - 48.0%, E/C ratio of 2.48-2.80 g x g(-1), and the concentration of ethanol of 92.0% - 92.7%.
Subject(s)
Chemical Precipitation , Chemistry, Pharmaceutical , Methods , Codonopsis , Chemistry , Drugs, Chinese Herbal , ChemistryABSTRACT
<p><b>BACKGROUND</b>The one-stage pull-through procedures for Hirschsprung's disease (HD) have become popular because it is well accepted by surgeons and mothers with no visible scar and a short hospital stay. It represents the latest development in the concept of a minimally invasive surgery for HD. We introduce a new method of transanal one-stage pull-through for Hirschsprung's disease, different from the transanal Soave procedure.</p><p><b>METHODS</b>One hundred and thirty-four patients aged 9 days to 5 years underwent a transanal one-stage pull-through procedure. The diagnosis was definite by barium enema or rectal biopsies preoperatively. The patients were anesthetized and placed in the lithotomy position. A urinary catheter was optional. Giving anorectal dilatations for half a minute, a pull-through of the rectum above the peritoneal reflection and into the intussusception was performed. Fine silk suturing was performed circumferentially at the level of that point which was used for traction for the distal end. Another circumferential suture was performed parallel 0.5 cm distance above the original one and used for traction for the proximal intestines. The full-thickness rectal wall was truncated between the above two circumferential sutures with cautery. The proximal intestines were pulled down and the mesenteric vessels were dissected with ligation until normal intestines were accessed; the presence of ganglion cells was determined by intraoperative rapid frozen section. The distal end was dissected anteriorly 2.5- 3.5 cm above the dentate line. The posterior rectal wall was split longitudinally and dissected to a point 0.5- 1.0 cm above the dentate line. The segment of the lesion was resected. The length of bowel resected ranged from 12 to 50 cm (median 16.5 cm). An oblique anastomosis was made.</p><p><b>RESULTS</b>The mean operating time was 70 minutes. Postoperative rectal dilation was not required. The patient tolerated feeding on the first postoperative day. Eighty-eight patients were followed-up. All these patients had 2- 3 bowel movements per day at postoperative month 1. They were discharged within 4.5 days after the operation. Six patients presented with complications. All recovered by reoperation or conservative treatments.</p><p><b>CONCLUSION</b>The modification of the transanal Swenson pull-through procedure for Hirschsprung's Disease is an easy adaptation to a well-established technique and has a reasonable result.</p>