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Background: The efficacy of cell implantation via 3D-spheroids to treat basal tone in fecal incontinence remains unclear. To address this, in this study, we aimed to identify cell differentiation and assess the development of a contractile phenotype corresponding to smooth muscle cells (SMCs) following implantation of 3D-spheroid and 2D-cultured human adipose stem cells (hASCs) in an in vivo internal anal sphincter (IAS)-targeted mouse model. Methods: We developed an IAS-targeted in vivo model via rapid freezing (at − 196 °C) of the dorsal layers of the region of interest (ROI) of the IAS ring posterior quarter, between the submucosal and muscular layers, following submucosal dissection (n = 60 rats). After implantation of tetramethylindocarbocyanine perchlorate (Dil)-stained 3D and 2D-cells into randomly allocated cryoinjured rats, the entire sphincter ring or only the cryoinjured ROI was harvested. Expression of SMC markers, RhoA/ROCKII and its downstream molecules, and fibrosis markers was analyzed. Dil, α-smooth muscle actin (α-SMA), and RhoA signals were used for cell tracking. Results: In vitro, 3D-spheroids exhibited higher levels of SMC markers and RhoA/ROCKII-downstream molecules than 2D-hASCs. The IAS-targeted cryoinjured model exhibited substantial loss of SMC layers of the squamous epithelium lining of the anal canal, as well as reduced expression of SMC markers and RhoA-related downstream molecules. In vivo, 3D-spheroid implantation induced SMC markers and contractile molecules weakly at 1 week. At 2 weeks, the mRNA expression of aSma, Sm22a, Smoothelin, RhoA, Mypt1, Mlc20, Cpi17, and Pp1cd increased, whereas that of fibrosis markers reduced significantly in the 3D-spheroid implanted group compared to those in the sham, non-implanted, and 2D-hASC implanted groups. Protein levels of RhoA, p-MYPT1, and p-MLC20 were higher in the 3D-spheroid-implanted group than in the other groups. At 2 weeks, in the implanted groups, the cryoinjured tissues (which exhibited Dil, α-SMA, and RhoA signals) were restored, while they remained defective in the sham and non-implanted groups. Conclusions: These findings demonstrate that, compared to 2D-cultured hASCs, 3D-spheroids more effectively induce a contractile phenotype that is initially weak but subsequently improves, inducing expression of RhoA/ROCKII-downstream molecules and SMC differentiation associated with IAS basal tone. [ABSTRACT FROM AUTHOR]

Abstract Background The efficacy of cell implantation via 3D-spheroids to treat basal tone in fecal incontinence remains unclear. To address this, in this study, we aimed to identify cell differentiation and assess the development of a contractile phenotype corresponding to smooth muscle cells (SMCs) following implantation of 3D-spheroid and 2D-cultured human adipose stem cells (hASCs) in an in vivo internal anal sphincter (IAS)-targeted mouse model. Methods We developed an IAS-targeted in vivo model via rapid freezing (at − 196 °C) of the dorsal layers of the region of interest (ROI) of the IAS ring posterior quarter, between the submucosal and muscular layers, following submucosal dissection (n = 60 rats). After implantation of tetramethylindocarbocyanine perchlorate (Dil)-stained 3D and 2D-cells into randomly allocated cryoinjured rats, the entire sphincter ring or only the cryoinjured ROI was harvested. Expression of SMC markers, RhoA/ROCKII and its downstream molecules, and fibrosis markers was analyzed. Dil, α-smooth muscle actin (α-SMA), and RhoA signals were used for cell tracking. Results In vitro, 3D-spheroids exhibited higher levels of SMC markers and RhoA/ROCKII-downstream molecules than 2D-hASCs. The IAS-targeted cryoinjured model exhibited substantial loss of SMC layers of the squamous epithelium lining of the anal canal, as well as reduced expression of SMC markers and RhoA-related downstream molecules. In vivo, 3D-spheroid implantation induced SMC markers and contractile molecules weakly at 1 week. At 2 weeks, the mRNA expression of aSma, Sm22a, Smoothelin, RhoA, Mypt1, Mlc 20 , Cpi17, and Pp1cd increased, whereas that of fibrosis markers reduced significantly in the 3D-spheroid implanted group compared to those in the sham, non-implanted, and 2D-hASC implanted groups. Protein levels of RhoA, p-MYPT1, and p-MLC20 were higher in the 3D-spheroid-implanted group than in the other groups. At 2 weeks, in the implanted groups, the cryoinjured tissues (which exhibited Dil, α-SMA, and RhoA signals) were restored, while they remained defective in the sham and non-implanted groups. Conclusions These findings demonstrate that, compared to 2D-cultured hASCs, 3D-spheroids more effectively induce a contractile phenotype that is initially weak but subsequently improves, inducing expression of RhoA/ROCKII-downstream molecules and SMC differentiation associated with IAS basal tone.

Purpose: This study aimed to clarify the relationship between changes in elasticity and anorectal function before and after chemoradiotherapy. Methods: This is a single-center prospective cohort study (Department of Surgical Oncology, The University of Tokyo). We established a technique to quantify internal anal sphincter hardness as elasticity using transanal ultrasonography with real-time tissue elastography. Twenty-seven patients with post-chemoradiotherapy rectal cancer during 2019–2022 were included. Real-time tissue elastography with transanal ultrasonography was performed before and after chemoradiotherapy to measure internal anal sphincter hardness as "elasticity" (hardest (0) to softest (255); decreased elasticity indicated sclerotic changes). The relationship between the increase or decrease in elasticity pre- and post-chemoradiotherapy and the maximum resting pressure, maximum squeeze pressure, and Wexner score were the outcome measures. Results: A decrease in elasticity was observed in 16/27 (59.3%) patients after chemoradiotherapy. Patients with and without elasticity decrease after chemoradiotherapy comprised the internal anal sphincter sclerosis and non-sclerosis groups, respectively. The maximum resting pressure post-chemoradiotherapy was significantly high in the internal anal sphincter sclerosis group (63.0 mmHg vs. 47.0 mmHg), and a majority had a worsening Wexner score (60.0% vs. 18.2%) compared with that of the non-sclerosis group. Decreasing elasticity (internal anal sphincter sclerosis) correlated with a higher maximum resting pressure (r = 0.36); no correlation was observed between the degree of elasticity change and maximum squeeze pressure. Conclusion: Internal anal sphincter sclerosis due to chemoradiotherapy may correlate to anorectal dysfunction. [ABSTRACT FROM AUTHOR]

Objectives: Daikenchuto (DKT) enhances the contraction of the internal anal sphincter (IAS) in patients with constipation and fecal incontinence; however, the mechanism of its action is unknown. We investigated the effects of the active ingredients of DKT (hydroxy-α-sanshool (HAS) and hydroxy-β-sanshool (HBS)) on the contractile activity of the canine rectum and IAS. Methods: Three male beagle dogs were prepared for each of the HAS, HBS, and control groups. Force transducers were attached to the rectal and IAS surfaces of the dogs, and the contractile responses were measured by telemetry under conscious conditions. HAS (10 mg/body) and HBS (2.5 mg/body) were administered intrarectally at doses previously identified from an effective dose of DKT extract (1.5 g/body), and contractile responses were recorded up to 6 h after administration. Contractile activity of the rectum and IAS was evaluated by observing the area under the curve (AUC) of the recorded contraction waveform. Plasma concentrations of HAS and HBS were measured before and after administration to confirm IAS exposure to both ingredients. Results: The mean AUC values of the IAS for the control, HAS, and HBS groups at 10 min after administration were 115, 87, and 220 (g-min), respectively, indicating a higher contraction in the HBS group, which was maintained for approximately 3 h. As for the rectum, no contractile response was observed in either the HAS or HBS groups. Plasma concentrations of both ingredients peaked at 20 min after administration. Conclusions: HBS could be involved in the contractile action of DKT on the IAS.

The vital anal sphincter has got two components. The external sphincter has somatic supply and the internal sphincter constituting smooth muscle is under autonomic control. The internal anal sphincter (IAS) provides resting pressure to keep the continent state for longer time and the external sphincter maximises the sphincteric action in emergency. Many feel the IAS is of doubtful sphincteric value as the continent state is maintained even if the IAS is cut during anal fistula surgery. This shows the inadequacy of knowledge on the internal sphincter and further study is needed. The internal anal sphincters were dissected in 29 human cadavers. The specimens were dissected under a 5 × magnification lance concentrating on the luminal surface in a different method. The new finds at the internal anal sphincters are the presence of a sheath, the thickness and the layout direction muscle change being seen differently at different zones. A midline fixing mechanism at 6 and 12 o'clock makes it to two functioning halves. The new findings could explain many anorectal clinical conditions better; may need modification in the surgical managements of anorectal pathology like fissure, haemorrhoidectomy and sphincter conservation surgery; and could help in post-operative management of pain and retention of urine. [ABSTRACT FROM AUTHOR]

Aims: Treatment outcomes for accidental bowel leakage (ABL) may be influenced by age‐related sarcopenia. We sought to determine if thickness of the anal sphincter complex on endoanal ultrasound correlated with function in women and men with ABL and if women demonstrated age‐related anal sphincter thinning. Methods: Consecutive patients with ABL presenting to our pelvic floor clinic from 2012 to 2017 were included. Clinical data were obtained from medical records. External anal sphincter (EAS), imaged by endoanal ultrasound at proximal, mid and distal locations, and IAS thickness were measured at 12, 3, 6, and 9 o'clock; puborectalis muscle (PRM) was measured at 4, 6, and 8 o'clock; and averaged. Anorectal manometry was conducted when clinically indicated. Data were compared using Mann–Whitney tests and linear regression. Results are reported as mean ± SD or median (IQR). Results: Women (n = 136) were younger than men (n = 26) (61 ± 13 vs. 67 ± 13 years, p = 0.02). More women than men had pelvic surgery and less had colorectal surgery, spinal disorders, or a history of smoking (p < 0.05). Eighty‐two percentage of women had an anal sphincter defect versus 31% of men (p < 0.01). All anal sphincter complex components were thinner in women than men with lower squeeze and resting pressures (p < 0.03), even in nulliparous women. Mean resting pressure was lower in older 6.1 (4.6–7.8) versus younger women 8.3 (5.0–12.9) mmHg, p = 0.04. Conclusions: Women, even nulliparous, with ABL demonstrate thinner and weaker anal sphincters than men, Aging correlated with an increase in anal sphincter thickness, suggesting that age‐related changes in the intrinsic components of the anal sphincter complex associated with ABL are complex and are not always well demonstrated on endoanal ultrasound. [ABSTRACT FROM AUTHOR]

Objective: Studies on development of an anal incontinence (AI) model targeting smooth muscle cells (SMCs) of the internal anal sphincter (IAS) have not been reported. The differentiation of implanted human adipose-derived stem cells (hADScs) into SMCs in an IAS-targeting AI model has also not been demonstrated. We aimed to develop an IAS-targeting AI animal model and to determine the differentiation of hADScs into SMCs in an established model. Materials and Methods: The IAS-targeting AI model was developed by inducing cryoinjury at the inner side of the muscular layer via posterior intersphincteric dissection in Sprague–Dawley rats. Dil-stained hADScs were implanted at the IAS injury site. Multiple markers for SMCs were used to confirm molecular changes before and after cell implantation. Analyses were performed using H&E, immunofluorescence, Masson's trichrome staining, and quantitative RT–PCR. Results: Impaired smooth muscle layers accompanying other intact layers were identified in the cryoinjury group. Specific SMC markers, including SM22α, calponin, caldesmon, SMMHC, smoothelin, and SDF-1 were significantly decreased in the cryoinjured group compared with levels in the control group. However, CoL1A1 was increased significantly in the cryoinjured group. In the hADSc-treated group, higher levels of SMMHC, smoothelin, SM22α, and α-SMA were observed at two weeks after implantation than at one week after implantation. Cell tracking revealed that Dil-stained cells were located at the site of augmented SMCs. Conclusions: This study first demonstrated that implanted hADSc restored impaired SMCs at the injury site, showing stem cell fate corresponding to the established IAS-specific AI model. [ABSTRACT FROM AUTHOR]

Objective To study the effect of lateral internal partial sphincterotomy and ligation on chronic anal fissure. Methods A total of 160 patients with chronic anal fissure were randomly divided into two groups. Eighty cases both in study group treated with lateral internal partial sphincterotomy combined with ligation and in control group treated with internal sphincter resection were studied. Incision size, pain score, bleeding score, anal function, hospital stay and incision would healing day on different days after operation in two groups were analyzed. Results Treatment efficacy was 100% in both groups. Cure rates was 100% in study group and 97.50% in control group (P

The complexity in the molecular mechanism of the internal anal sphincter (IAS) limits preclinical or clinical outcomes of fecal incontinence (FI) treatment. So far, there are no systematic reviews of IAS translation and experimental studies that have been reported. This systematic review aims to provide a comprehensive understanding of IAS critical role in FI. Previous studies revealed the key pathway for basal tone and relaxation of IAS in different properties as follows; calcium, Rho-associated, coiled-coil containing serine/threonine kinase, aging-associated IAS dysfunction, oxidative stress, renin-angiotensin-aldosterone, cyclooxygenase, and inhibitory neurotransmitters. Previous studies have reported improved functional outcomes of cellular treatment for regeneration of dysfunctional IAS, using various stem cells, but did not demonstrate the interrelationship between those results and basal tone or relaxation-related molecular pathway of IAS. Furthermore, these results have lower specificity for IAS-incontinence due to the included external anal sphincter or nerve injury regardless of the cell type. An acellular approach using bioengineered IAS showed a physiologic response of basal tone and relaxation response similar to human IAS. However, in both cellular and acellular approaches, the lack of human IAS data still hampers clinical application. Therefore, the IAS regeneration presents more challenges and warrants more advances.

Systemic sclerosis is an autoimmune disorder which frequently affects the gastrointestinal tract. Anorectal dysfunction is common in systemic sclerosis and is manifested mainly by atrophy of internal anal sphincter. Faecal incontinence is the result of internal anal sphincter atrophy secondary to systemic sclerosis. In this study, we aimed to assess the internal anal sphincter in 17 patients with faecal incontinence and systemic sclerosis using anorectal manometry and endoanal ultrasound and compare them with an age and gender-matched control group without systemic sclerosis. Most patients have limited cutaneous systemic sclerosis. Majority of the patients with systemic sclerosis and faecal incontinence presented with symptoms of faecal leakage and urgency. Systemic sclerosis patients had low basal sphincter pressures. The mean thickness of internal anal sphincter in systemic sclerosis group was significantly lower than the control group (p < 0.001). Rectal sensation is preserved in systemic sclerosis. There was no difference in the mean thickness of the external anal sphincter between the two groups. To conclude internal anal sphincter is atrophic in systemic sclerosis resulting in decreased resting sphincter pressures and passive faecal leakage. Further investigations and studies are needed to determine the natural course of faecal incontinence in systemic sclerosis, associated risk factors and efficacy of therapeutic interventions., Competing Interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship and/or publication of this article., (© The Author(s) 2024.)

PurposeRadical surgery is the most effective treatment for Hirschsprung's disease. However, some children still have symptoms of intestinal dysfunction such as constipation, abdominal distension, and recurrent enterocolitis after operation. The purpose of this study was to evaluate treatment outcomes of postoperative intestinal dysfunction in children with Hirschsprung's disease by using the principle of “anorectal balance”.MethodsThe clinical data of postoperative intestinal dysfunction in children with Hirschsprung's disease in the single treatment group from July 2019 to July 2021 were retrospectively analyzed. All the enrolled children underwent botulinum toxin injection (2.5 U/kg); 3 to 6 months later, the injection was performed again; the children who had received more than two botulinum toxin injections underwent the internal sphincter myectomy. Anorectal manometry was performed routinely after operation, and abdominal distension and defecation were recorded.ResultsA total of thirty children with postoperative intestinal dysfunction underwent radical surgery for Hirschsprung's disease were included in this study. Symptoms of constipation, abdominal distension and enterocolitis were improved after botulinum toxin injections in most children compared to before surgery (P

Introduction: one of the most common reported chief complaints in visits to pediatricians is constipation. Although in a majority of cases with no anatomical defect, dietary manipulation, stool softeners, and oral laxatives are successful, some patients fail to respond. Internal Anal Sphincter (IAS) Achalasia is one of the causes of constipation.It results in failure of IAS relaxation and has similar clinical presentation to Hirschsprung’s disease with absence of rectosphincteric inhibitory reflex on anorectal manometry (ARM) and presence of ganglion cells on rectal biopsy. Although posterior internal anal sphincter myectomy (ISM) is considered the standard treatment for IASA, some cases fail to respond and present with intractable constipation which may be associated with soiling. This research aims to assess the role of botox injection for treatment of patients who presented with intractable constipation and have already beentreated by posterior IAS myectomy. Materials and Methods:Internal anal sphincter Botox injection was performed (with a dose of 20 U/Kg) in 14 patients with internal anal sphincter achalasia (IASA); who had presented with intractable constipationafter being treated by posterior internal anal sphincter myectomy. Patients were followed for 2 years after injection. Result: of all 14 patients with persistent constipation (resistant to oral laxatives), 12 patients (85.7%) had regular bowel function for more than 6 months after botox injection therapy (P < 0.05). Of all 14 patients that had needed rectal enema for defecation, no patient needed rectal enema after botox injection therapy (P < 0.05). Of 5 patients with fecal soiling before botox injection therapy (4 had occasionalsoiling, and 1 had soiling every day without social problems) only a single patient experienced transient fecal soiling for 2 weeks after botox injection therapy (P < 0.05). No patient needed another botox injection in 2 years of follow up. Conclusion: IAS Botox injection therapy (BIT) was successfully used to manage IASA patients who had presented with intractable constipation after posterior myectomy. This method significantly reduces the need for laxatives and rectal enema; and improves constipation, fecal soiling and bowel movements at the same time.

Objectives: This study aimed to elucidate the effect of the extract of daikenchuto (DKT), a Japanese Kampo medicine, on the contractile activity of the internal anal sphincter in conscious dogs. Methods: Force transducers were attached to the serosal surface of the rectum and the internal anal sphincter of male beagle dogs. In addition, the contractile activity of the rectum and the internal anal sphincter was continuously measured until 6 h after DKT administration via telemetry in the conscious state. The DKT dose was 1.5 g/body, and the administration route was intrarectal in the expectation of a direct effect on the rectoanal region. DKT was re-administered to the same animal after drug withdrawal, and the plasma concentrations of hydroxy-α-sanshool (HAS) and hydroxy-β-sanshool (HBS) before and after administration were measured. Results: After DKT administration, the contractile activity of the internal anal sphincter immediately increased, peaked at 10 min, continued for 1 h, and had almost disappeared after 4 h. Rectal contraction differed from that of the internal anal sphincter, with no significant contraction observed. HAS and HBS were found in the plasma of animals administered with DKT and persisted up to 2 h after the administration. Conclusions: This is the first report on in vivo telemetry demonstrating that DKT exhibited contractile effects on the dog's internal anal sphincter. The increased anal pressure and improvement of fecal incontinence symptoms observed in previous clinical studies may have been based on this sphincter contraction.

A persistent basal tone in the internal anal sphincter (IAS) is essential for keeping the anal canal closed and fecal continence; its inhibition via the rectoanal inhibitory reflex (RAIR) is required for successful defecation. However, cellular signals underlying the IAS basal tone remain enigmatic. Here we report the origin and molecular mechanisms of calcium signals that control the IAS basal tone, using a combination approach including a novel IAS slice preparation that retains cell arrangement and architecture as in vivo, 2‐photon imaging, and cell‐specific gene‐modified mice. We found that IAS smooth muscle cells generate two forms of contractions (i.e., phasic and sustained contraction) and Ca2+ signals (i.e., synchronized Ca2+ oscillations [SCaOs] and asynchronized Ca2+ oscillations [ACaOs]) that last for hours. RyRs, TMEM16A, L‐type Ca2+ channels, and gap junctions are required for SCaOs, which account for phasic contraction and 75% of sustained contraction. Nevertheless, only RyRs are required for ACaOs, which contribute 25% of sustained contraction. Nitric oxide, the primary neurotransmitter mediating the RAIR, blocks both types of Ca2+ signals, leading to IAS's full relaxation. Our results show that the oscillating nature of Ca2+ signals generates and maintains the basal tone without causing cytotoxicity to IAS. Our study provides insight into fecal continence and normal defecation. [ABSTRACT FROM AUTHOR]

Hirschsprung-associated enterocolitis (HAEC) is a serious potential complication after primary pull-through surgery for Hirschsprung's disease (HSCR). Administration of anal botulinum toxin (BT) injection may improve obstructive symptoms at the internal anal sphincter, leading to improved fecal passage. The timing of administration and effects on delay or prevention of HAEC are unknown. We hypothesized that BT administration increased the postoperative time to HAEC and aimed to investigate whether anal BT administration after primary pull-through surgery for HSCR is associated with increased time to inpatient HAEC admission development. We performed a retrospective cohort study examining children with HSCR at US children's hospitals from 2008 to 2018 using the Pediatric Health Information System database with an associated primary pull-through operation performed before 60 d of age. The intervention assessed was the administration of BT concerning the timing of primary pull-through, and two groups were identified: PRO (received BT at or after primary pull-through, before HAEC) and NOT (never received BT, or received BT after HAEC). The primary outcome was time from pull-through to the first HAEC admission. The Cox proportional hazards model was developed to examine the BT administration effect on the primary outcome after controlling for patient-level covariates. We examined a total of 1439 children (67 in the PRO and 1372 in the NOT groups). A total of 308 (21.4%) developed at least one episode of HAEC, including 76 (5.3%) who had two or more episodes. Between 2008 and 2018, the frequency of BT administration has increased from three to 20 hospitals with a frequency of administration between 2.2% and 16.2%. Prophylactic BT (PRO) was not associated with increased time to HAEC event on adjusted analysis. Among children with HSCR undergoing primary pull-through surgery, prophylactic BT administration did not demonstrate increased time to first HAEC event. A better-powered study with prophylactic BT is required to determine the effect on HAEC occurrence and timing. Level II (retrospective cohort study). [ABSTRACT FROM AUTHOR]

Background: The Fistula disease is considered common surgical case in the surgical wards of the Baquba teaching hospital, and consider as a complication of the anorectal abscess. Objective: To investigate the incidence of cases that infect with fistula in ano in subsequent to different types of anorectal abscesses. Patients and Methods: This study performed in the Baquba teaching hospital in a period from January 2016 until Jun 2018 including 216 patients (124 male and 92 female); all patients were included in the study. Samples of the patients classified into three groups according to the type of management. Results: The results show that the high incidence of fistula in ano is appearing in patients associated with hemorrhoids 8.84%, and high percent in patients who had a perianal abscess (63.48%) Regarding the distribution of cases according to age and sex, a low percentage of cases appear in age (1-10) with 6.45% and 2.18% in males and females respectively. While the highest percentage appears in the males at age (21-30) with 37.11% and in females is at the age (11-20) with 29.35%. And by the chi-square value for males is 16.37 and for females is 9.94 in a significant value of p=0.01 and p=0.05 respectively. Conclusion: Fistula in ano can be associated with cases have hemorrhois, and more present with patients who have a perianal abscess, and the early drainage of the abscess can prevent development of the fistula. [ABSTRACT FROM AUTHOR]

Background: Several sphincter saving techniques have been described for complex anal fistula (CAF) with variable outcomes. The present trial aimed to compare two techniques for CAF; the drained mucosal flap technique and rerouting Seton around the internal anal sphincter (IAS).Methods: Adult patients with high trans-sphincteric anal fistula were randomly assigned to one of two groups: group I underwent mucosal advancement flap with drainage Seton rerouted around the external anal sphincter, and group II underwent rerouting Seton around the IAS. The two groups were compared in terms of the incidence of postoperative fecal incontinence (FI), healing of fistula, complications, and changes in anal pressures.Results: 97 patients (80 male) of a mean age of 39.5 years were included. One patient developed FI in group I versus 7 in group II (p = 0.03). Failure of healing occurred in 2 patients in group I and 4 in group II (p = 0.43). In group II, the average time for spontaneous fall of Seton was 14 ± 2.8 days whereas in group I the average time for removal of Seton was 40 ± 14.9 days (p < 0.0001). There were no significant differences between the two groups in complication rate. Postoperatively, the decrease in resting anal pressure was significant in Group II but not group I.Conclusion: The drained mucosal flap technique was associated with significantly lower incidence of FI, yet longer operative time and longer time to complete healing compared to rerouting Seton around the IAS. The success rates of both techniques was comparable. [ABSTRACT FROM AUTHOR]