Fluid-particle-structure interaction in single shot peening.

Shot peening is a widely used cold-working process. Physical phenomena of shot peening are analyzed using the developed fluid-particle-structure coupled solver. The influences of the flow field and shot peening parameters such as the shot impact velocity and shot size are investigated in the case of the falling, impacting, and rebounding single particle. The weakly coupled solver applies the immersed boundary method which enables direct evaluation of the interactions between the unsteady flow field and moving/deforming objects. The elastoplastic object of AISI4340 during the collision of rigid steel shot is analyzed dynamically using the finite element method. Consequently, it is clarified that the flow field of the post-collision between the shot and structure can be characterized by the relative Reynolds number, which is based on the shot diameter and relative velocity between the uniform flow and rebounding shot velocities. As the relative Reynolds number increases, the complex flow field and vortex structures are generated at the collision location. These fluid structures affect the collision phenomena resulting in the random behavior of the shot and the asymmetric indentation in the structure.

Urosymphyseal fistula development following treatment for radiation-induced urethral stenosis in three patients with prostate cancer.

Introduction: Urosymphyseal fistula is a rare and devastating complication that develops after radiation therapy for prostate cancer and is often triggered by the treatment of radiation-induced urethral stenosis. Here, we report our experience with urosymphyseal fistulas in three patients with prostate cancer. Case presentation: Three patients with prostate cancer developed urethral stenosis after radiotherapy. The management of urethral stenosis was suprapubic tube placement in case 1, direct vision internal urethrotomy in case 2, and excision with primary anastomosis in case 3. All patients presented with severe suprapubic or thigh pain or both. Urosymphyseal fistulas were detected on magnetic resonance imaging. Conservative treatment was unsuccessful, and all patients required debridement of the necrotic pubic symphysis and simple cystectomy. In cases 1 and 2, ileal conduit urinary diversion was performed. Conclusion: Urologists need to be aware that urosymphyseal fistulas can occur in irradiated patients with prostate cancer, especially after urethral stenosis treatment.

[TREATMENT OUTCOMES OF BLADDER NECK CONTRACTURE AFTER TRANSURETHRAL PROSTATE SURGERY].

(Introduction) A known complication of the surgical treatment of benign prostatic hyperplasia (BPH) is bladder neck contracture (BNC). BNC is often treated using transurethral incision of the bladder neck (TUI-BN); however, there are few reports on the outcomes of TUI-BN. Therefore, we examined the outcomes of patients who underwent TUI-BN after transurethral prostate surgery. (Material and methods) We retrospectively examined 25 patients who underwent TUI-BN between February 2015 and January 2021 for the following: (1) patients' characteristics; (2) the time from transurethral prostate surgery to TUI-BN; (3) the trigger of BNC diagnosis; (4) surgical procedure of BNC repair/perioperative course; (5) micturition function immediately after TUI-BN; and (6) Postoperative outcomes. (Results) The median age of the patients was 77 years, and the surgical procedures for BPH were transurethral resection of the prostate (TURP) in four cases, transurethral resection in saline plasma vaporization of the prostate (TURisP) in nine cases, and transurethral enucleation with bipolar (TUEB) in 12 cases. The median time to onset of BNC symptoms was 364 days, and 18 patients (72%) were diagnosed within 2 years. The trigger of BNC diagnosis was urinary symptoms in 21 cases, of which 16 patients had exacerbation of urination. The median duration of the surgical procedure of BNC repair was 14 min, and the incisions most frequently used (in 44% of cases) were at the 4 o'clock and 8 o'clock positions. Transient stress urinary incontinence was observed as a complication in three cases. In the 4 o'clock and 8 o'clock incisions, the maximum urine flow rate improved significantly (11.1 mL/s perioperatively vs. 20.9 mL/s postoperatively; P=0.004). These symptoms improved in 16 of the 21 symptomatic cases, and the maximum urine flow rate improved significantly (P< 0.01). The median observation period after surgery was 170 days; eight postoperative patients were lost to follow up. There were two cases of recurrence. (Conclusions) BNC is likely to develop within 2 years after transurethral prostate surgery. In this study, the success rate of the initial TUI-BN was 92%, as reoperation was required in two cases; however, the overall prognosis was good.

A successfully treated case of Lemmel syndrome with pancreaticobiliary maljunction: A case report.

BACKGROUND: Lemmel syndrome is a rare condition that leads to cholangitis and/or pancreatitis due to intraduodenal diverticulum. Surgery is considered for the treatment of severe or repeated symptoms in patients with this condition. CASE PRESENTATION: An 81-year-old woman was admitted to our hospital, complaining of general fatigue, BT 38.8 degree, and right hypochondoralgia. Her hepatobiliary enzyme levels were elevated, and enhanced abdominal computed tomography revealed dilation of the common bile duct and intraduodenal diverticulum. After restarting oral intake, her symptoms were exacerbated. Endoscopic retrograde cholangio-pancreatography (ERCP) revealed pancreaticobiliary maljunction and parapapillary diverticulum. Under a diagnosis of Lemmel syndrome with pancreaticobiliary maljunction complicated by acute pancreatitis and cholangitis, we performed extrahepatic bile duct resection with cholecystectomy and papilloplasty. Her postoperative course was uneventful, and the patient was discharged 20 days after surgery. She remains well at 5 months after surgery. CONCLUSION: We herein report a successfully diagnosed and treated case of Lemmel syndrome with pancreaticobiliary maljunction.

[Pharmaceutical Properties of Rikkunshito Extract Suppository and Bioequivalence by Pharmacokinetic Parameters and Effectiveness against Nausea and Vomiting and Anorexia in Rats].

　In patients with cancer, it is difficult to continue medical treatment owing to nausea and vomiting (NV). Therefore, it is important to avoid these problems for improving the patient's QOL. Rikkunshito extract (RK) possesses antiemetic effects and is used in combination in cancer therapy. However, patients with cancer find it difficult to take the medicine orally for the treatment of NV and anorexia owing to the characteristic smell and taste of traditional Chinese medicine. We examined the pharmaceutical properties of RK suppository for hospital use, assessed bioequivalence by using pharmacokinetic parameters, and determined its effectiveness against NV and anorexia in rats. In this study, RK suppository was prepared by using RK formulation (A, B, and C) and Witepsol (H and S) (AH, BH, CH, AS, BS, and CS). Pharmaceutical properties, namely, hardness, dispersibility, long-term stability, and drug (hesperidin and glycyrrhizic acid) release were measured for AH, BH, AH, and AS. The pharmacokinetic parameters, effectiveness of substance P against NV and anorexia, and serotonin-activated ghrelin levels were assessed for BH only. AH, BH, AS, and AS demonstrated uniform and sufficient hardness. The release rate of oleaginous components, such as glycyrrhizic acid, did not change significantly, while that of water soluble components, such as hesperidin, decreased when compared with that in powder formulations A and B. NV and anorexia improved in rats administered BH compared with the control group. BH suppository showed effectiveness in terms of both physicochemical property and bioequivalence for hospital use.

Effects of a novel method for enteral nutrition infusion involving a viscosity-regulating pectin solution: A multicenter randomized controlled trial.

BACKGROUND & AIMS: The initial complications associated with infusion of enteral nutrition (EN) for clinical and nutritional care are vomiting, aspiration pneumonia, and diarrhea. There are many recommendations to prevent these complications. A novel method involving a viscosity-regulating pectin solution has been demonstrated. In Japan, this method along with the other so-called "semi-solid EN" approaches has been widely used in practice. However, there has been no randomized clinical trial to prove the efficiency and safety of a viscosity-regulating pectin solution in EN management. Therefore, we planned and initiated a multicenter randomized controlled trial to determine the efficiency and safety. METHODS: This study included 34 patients from 7 medical institutions who participated. Institutional review board (IRB) approval was obtained from all participating institutions. Patients who required EN management were enrolled and randomly assigned to the viscosity regulation of enteral feeding (VREF) group and control group. The VREF group (n = 15) was managed with the addition of a viscosity-regulating pectin solution. The control group (n = 12) was managed with conventional EN administration, usually in a gradual step-up method. Daily clinical symptoms of pneumonia, fever, vomiting, and diarrhea; defecation frequency; and stool form were observed in the 2 week trial period. The dose of EN and duration of infusion were also examined. RESULTS: A favorable trend for clinical symptoms was noticed in the VREF group. No significant differences were observed in episodes of pneumonia, fever, vomiting, and diarrhea between the 2 groups. An apparent reduction in infusion duration and hardening of stool form were noted in the VREF group. CONCLUSIONS: The novel method involving a viscosity-regulating pectin solution with EN administration can be clinically performed safely and efficiently, similar to the conventional method. Moreover, there were benefits, such as improvement in stool form, a short time for EN infusion, and a reduction in vomiting episodes, with the use of the novel method. This indicates some potential advantages in the quality of life among patients receiving this novel method.

Impact of acute fat mobilisation on the pharmacokinetics of the highly fat distributed compound TAK-357, investigated by physiologically based pharmacokinetic (PBPK) modeling and simulation.

In a dog toxicokinetic study, an unusual plasma concentration increase of the highly lipophilic compound TAK-357 was observed 2 weeks after termination of a 2-week repeated dosing in one dog with acute body weight loss. The present study investigates the cause of this increase. A physiologically based pharmacokinetic (PBPK) model was constructed using the rat and dog pharmacokinetic data. Using the constructed model, the TAK-357 concentration profile in the case of body weight change was simulated. The PBPK model-derived simulation suggested that redistribution from adipose tissues to plasma due to a loss of body fat caused the observed concentration increase of TAK-357 in dog plasma. The analysis demonstrates that the disposition of a highly lipophilic and fat-distributed compound can be affected by acute changes in adipose tissue mass. PBPK modeling and simulation proved to be efficient tools for the quantitative hypothesis testing of apparently atypical PK phenomena resulting from acute physiological changes.

Clinical efficacy of Daikenchuto for gastrointestinal dysfunction following colon surgery: a randomized, double-blind, multicenter, placebo-controlled study (JFMC39-0902).

OBJECTIVE: This exploratory trial was performed to determine whether Daikenchuto accelerates recovery of gastrointestinal function in patients undergoing open colectomy for colon cancer. METHODS: A total of 386 patients undergoing colectomy at 1 of the 51 clinical trial sites in Japan from January 2009 to June 2011 were registered for the study (JFMC39-0902). Patients received either placebo or Daikenchuto (15.0 g/day, t.i.d) between post-operative day 2 and post-operative day 8. Primary end-points included time to first bowel movement, frequency of bowel movement and stool form. The incidence of intestinal obstruction was evaluated post-operatively. The safety profile of Daikenchuto until post-operative day 8 was also evaluated. RESULTS: The results for 336 patients (Daikenchuto, n = 174; placebo, n = 162) were available for statistical analysis. The time to first bowel movement did not differ significantly between the two groups. All patients reported having diarrhea or soft stools immediately after surgery, and the time until stool normalization (50th percentile) in the Daikenchuto and placebo groups was 6 days and 7 days, respectively. The placebo group had a significantly greater number of hard stools at post-operative day 8 (P = 0.016), and bowel movement frequency continued to increase until post-operative day 8 as well. In contrast, bowel movement frequency in the Daikenchuto group increased until post-operative day 6, however decreased from post-operative day 7 and was significantly lower at post-operative day 8 compared with the placebo group (P = 0.024). CONCLUSION: The moderate effects of Daikenchuto were observed ∼1 week after the operation. Although Daikenchuto had an effect on gastrointestinal function after open surgery in patients with colon cancer, this study did not show its clinical benefits adequately.

Effect of Dai-kenchu-to on gastrointestinal motility and gastric emptying.

BACKGROUND/AIMS: The gastrointestinal symptoms accompanying dysfunction of the remnant stomach were seen after pylorus-preserving operation. Against such complications, Dai-kenchu-to (DKT) is used, but scientific evidences for efficacy are poor. The effect of DKT on gastrointestinal motility and gastric emptying after pylorus-preserving operation was investigated. METHODS: Using beagle dogs, the experimental models mimicking the state after pylorus-preserving pancreaticoduodenectomy were prepared. We sutured strain gauge transducers to the stomach, duodenum and jejunum and inserted indwelling tubes into the stomach. About 4 weeks after operation, DKT 0.1g/kg was administered during the fasting or fed state. At the same time, the gastric emptying was evaluated by the acetoaminophene method. RESULTS: In the fasting state, administration of DKT enhanced the gastrointestinal motility and accelerated gastric emptying. In the postprandial state, no apparent effect on motility was seen. CONCLUSION: DKT enhances the gastrointestinal motility after pylorus-preserving pancreaticoduodenectomy in the fasting state. The effect of DKT may not be related to the continuity of the intramural nerve.

Early postoperative enteral nutrition is useful for recovering gastrointestinal motility and maintaining the nutritional status.

PURPOSE: The efficacy of enteral nutrition in postoperative nutritional management is known, but the effects on gastrointestinal motility and nutrition have not yet been elucidated. The purpose of this study was to compare the effects of enteral and parenteral nutrition soon after open abdominal surgery on gastrointestinal motility and nutritional status. METHODS: A partial resection of rectum models was prepared to compare two types of nutrient administration: enteral nutrition and total parenteral nutrition. The differences between the effects of nutrition types in terms of gastrointestinal motility and nutritional status were investigated. RESULTS: Enteral nutrition contributed to recovery of gastrointestinal motility and maintenance of nutritional status. CONCLUSION: Enteral nutrition should therefore be initiated soon after surgery if the gastrointestinal tract is available.

Effect of Dai-kenchu-to on gastrointestinal motility based on differences in the site and timing of administration.

The purpose of this study was to investigate the effects of the herbal medicine dai-kenchu-to on gastrointestinal motility based on differences in the administration site and timing. We sutured strain-gauge transducers to the stomach (three), duodenum (one), jejunum (one), ileum (one), and colon (two) and inserted indwelling tubes into the stomach, jejunum, and proximal colon of beagles. Dai-kenchu-to was administered to each site during the fasting or fed state. During the fasting state, the prokinetic effects of dai-kenchu-to were evident at all administration sites. The effects were attenuated during the fed state. With intracolonic administration, a contraction similar to the giant migrating contraction-like contraction was induced during the fasting and the fed state, and defecation occurred. Despite the differences in administration site and timing, no contraction complex appeared orad to the administration sites. These results indicate that the prokinetic effects of dai-kenchu-to differ with the site or timing of administration.

Usefulness of automatic triangular anastomosis for esophageal cancer surgery using a linear stapler (TA-30).

In a clinical evaluation, thirty-one patients with thoracic esophageal cancer who were treated from 1997 to 2000 were selected as subjects including those who underwent hand sewn anastomosis method, circular stapler method and triangular anastomosis method. Incidence of anastomosis failure was 27.3%, 25.0% and 8.3% for the hand sewn anastomosis method, circular stapler method and triangular anastomosis method, respectively. Anastomosis stenosis was found in 32.4%, 45.6% and 8.3% for the hand sewn anastomosis method, circular stapler method and triangular anastomosis method, respectively. In the basic examination, reduction rate of anastomosis caliber was 22.1+/-4.8%, 14.9+/-1.4% and 7.37+/-0.9%, for the hand sewn anastomosis method, circular stapler method and triangular anastomosis method. Microscopic evaluation revealed serious problems with the circular stapler method. The cause of anastomotic stenosis may include the fact that if anastomosis is performed by a circular stapler method, all the layers of gastrointestinal tract are punched out at the anastomosis portion, and mucosal conjugation is not observed and the muscular layer is exposed in the inner lumen of the gastrointestinal tract. Taking that the ulcer is formed circularly at the anastomotic portion into account, it is easily understood that this circular ulcer develops into stenosis in the healing process. The advantage of triangular anastomosis for esophago-gastric anastomosis is less suture failure, and is extremely advantageous for prevention of stenosis at the anastomotic portion when compared with other anastomosis methods. However, with regard to the healing process of eversion anastomosis in gastrointestinal tract instrumental anastomosis, detailed examination is expected hereafter.

[PACS for multi-slice CT--seamless integration implementing 3D and 4D workstations].

A PACS system for data management in multi-slice CT examination was upgraded using interactive 3D and 4D workstations and network computing technology. We categorized the original PACS (CT-PACS) as follows: (1) a fault-tolerant system linked with the hospital information system (HIS) and radiology information system (RIS); (2) an interactive network system using a workstation with real-time 3D and 4D reconstruction; (3) a system for research and development of software for 3D image analysis on the CT-PACS system. Because of the use of cooperative diagnostic supporting tools, no major problems occurred in daily clinical practice or research and education. In conclusion, CT-PACS with real-time 3D and 4D workstations was found to be helpful to radiologists and researchers in reading and analyzing large volumetric data.

[Etiology, diagnosis, and treatment of spontaneous esophageal rupture].

In some unique cases of idiopathic rupture of the esophagus where abscess is confined within the mediastinum and signs of infection are very slight, the patient's life can be saved with conservative treatment. However, because idiopathic esophageal rupture is related to vomiting in many cases, contamination of the mediastinum and thoracic cavity by vomit is severe, and prompt diagnosis and early surgery are crucial to save the patient's life. Gastrointestinal contents from idiopathic esophageal rupture pour out via the mediastinum from the bilateral sides of the vertebral body to form extrapleural abscess on the wall side. During observation, the abscess may sometimes enlarge, progress, and extend. Therefore, several computed tomography scans and ECHO need to be performed, followed by on-target drainage. Basically, idiopathic esophageal rupture cannot be cured by palliative treatment alone, and we need to undertake surgical treatment, as well as concomitant conservative treatments including blood purification (polymyxin, continuous hemodiafiltration), enteral feeding, and antibiotic therapy.