Evaluation of a Rapid and Accessible Reverse Transcription-Quantitative PCR Approach for SARS-CoV-2 Variant of Concern Identification.

The ability to distinguish between severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern (VOCs) is of ongoing interest due to differences in transmissibility, responses to vaccination, clinical prognosis, and therapy. Although detailed genetic characterization requires whole-genome sequencing (WGS), targeted nucleic acid amplification tests can serve a complementary role in clinical settings, as they are more rapid and accessible than sequencing in most laboratories. We designed and analytically validated a two-reaction multiplex reverse transcription-quantitative PCR (RT-qPCR) assay targeting spike protein mutations L452R, E484K, and N501Y in reaction 1 and del69-70, K417N, and T478K in reaction 2. This assay had 95 to 100% agreement with WGS for 502 upper respiratory tract swab samples collected between 26 April 2021 and 1 August 2021, consisting of 43 Alpha, 2 Beta, 20 Gamma, 378 Delta, and 59 non-VOC infections. Validation in a separate group of 230 WGS-confirmed Omicron variant samples collected in December 2021 and January 2022 demonstrated 100% agreement. This RT-qPCR-based approach can be implemented in clinical laboratories already performing SARS-CoV-2 nucleic acid amplification tests to assist in local epidemiological surveillance and clinical decision-making.

Multiplex SARS-CoV-2 Genotyping Reverse Transcriptase PCR for Population-Level Variant Screening and Epidemiologic Surveillance.

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants with concerning phenotypic mutations is of public health interest. Genomic surveillance is an important tool for a pandemic response, but many laboratories do not have the resources to support population-level sequencing. We hypothesized that a nucleic acid amplification test (NAAT) to genotype mutations in the viral spike protein could facilitate high-throughput variant surveillance. We designed and analytically validated a one-step multiplex allele-specific reverse transcriptase PCR (RT-qPCR) to detect three nonsynonymous spike protein mutations (L452R, E484K, N501Y). Assay specificity was validated with next-generation whole-genome sequencing. We then screened a large cohort of SARS-CoV-2-positive specimens from our San Francisco Bay Area population. Between 1 December 2020 and 1 March 2021, we screened 4,049 unique infections by genotyping RT-qPCR, with an assay failure rate of 2.8%. We detected 1,567 L452R mutations (38.7%), 34 N501Y mutations (0.84%), 22 E484K mutations (0.54%), and 3 (0.07%) E484K plus N501Y mutations. The assay had perfect (100%) concordance with whole-genome sequencing of a validation subset of 229 specimens and detected B.1.1.7, B.1.351, B.1.427, B.1.429, B.1.526, and P.2 variants, among others. The assay revealed the rapid emergence of the L452R variant in our population, with a prevalence of 24.8% in December 2020 that increased to 62.5% in March 2021. We developed and clinically implemented a genotyping RT-qPCR to conduct high-throughput SARS-CoV-2 variant screening. This approach can be adapted for emerging mutations and immediately implemented in laboratories already performing NAAT worldwide using existing equipment, personnel, and extracted nucleic acid.

Significance of research in a surgeon-scientist's career - A view from Japan.

Reflections of academic pediatric surgery in Japan are shared by the authors. As in most areas of surgical practice committement and life long dedication are emphasized as the key(s) to success. An enquiring mind is always an advantage.

Mammary Stem Cell Self-Renewal Is Regulated by Slit2/Robo1 Signaling through SNAI1 and mINSC.

Tissue homeostasis requires somatic stem cell maintenance; however, mechanisms regulating this process during organogenesis are not well understood. Here, we identify asymmetrically renewing basal and luminal stem cells in the mammary end bud. We demonstrate that SLIT2/ROBO1 signaling regulates the choice between self-renewing asymmetric cell divisions (ACDs) and expansive symmetric cell divisions (SCDs) by governing Inscuteable (mInsc), a key member of the spindle orientation machinery, through the transcription factor Snail (SNAI1). Loss of SLIT2/ROBO1 signaling increases SNAI1 in the nucleus. Overexpression of SNAI1 increases mInsc expression, an effect that is inhibited by SLIT2 treatment. Increased mInsc does not change cell proliferation in the mammary gland (MG) but instead causes more basal cap cells to divide via SCD, at the expense of ACD, leading to more stem cells and larger outgrowths. Together, our studies provide insight into how the number of mammary stem cells is regulated by the extracellular cue SLIT2.

SLIT/ROBO2 signaling promotes mammary stem cell senescence by inhibiting Wnt signaling.

WNT signaling stimulates the self-renewal of many types of adult stem cells, including mammary stem cells (MaSCs), but mechanisms that limit this activity are poorly understood. Here, we demonstrate that SLIT2 restricts stem cell renewal by signaling through ROBO2 in a subset of basal cells to negatively regulate WNT signaling. The absence of SLIT/ROBO2 signaling leads to increased levels of nuclear ß-catenin. Robo2 loss does not increase the number of stem cells; instead, stem cell renewal is enhanced in the absence of SLIT/ROBO2 signaling. This is due to repressed expression of p16(INK4a), which, in turn, delays MaSC senescence. Together, our studies support a model in which SLITs restrict the expansion of MaSCs by countering the activity of WNTs and limiting self-renewal.

Self-regulated left-right asymmetric expression of Pitx2c in the developing mouse limb.

The transcription factor Pitx2c is expressed in primordial visceral organs in a left-right (L-R) asymmetric manner and executes situs-specific morphogenesis. Here we show that Pitx2c is also L-R asymmetrically expressed in the developing mouse limb. Human PITX2c exhibits the same transcriptional activity in the mouse limb. The asymmetric expression of Pitx2c in the limb also exhibits dorsal-ventral and anterior-posterior polarities, being confined to the posterior-dorsal region of the left limb. Left-sided Pitx2c expression in the limb is regulated by Nodal signaling through a Nodal-responsive enhancer. Pitx2c is expressed in lateral plate mesoderm (LPM)-derived cells in the left limb that contribute to various limb connective tissues. The number of Pitx2c(+) cells in the left limb was found to be negatively regulated by Pitx2c itself. Although obvious defects were not apparent in the limb of mice lacking asymmetric Pitx2c expression, Pitx2c may regulate functional L-R asymmetry of the limb.

Surgical treatment of anorectal malformations.

The goal of surgery for anorectal malformations (ARM) is to achieve good bowel, urinary, and sexual functions, as well as the ability for children to become healthy adults. Various surgical procedures and surgical management protocols have been explored or devised by pediatric surgeons. These are described in this review. Making a correct type classification by invertography, fistelography and urethrography in the neonatal period allows pediatric surgeons to select an appropriate surgical strategy. Surgery for low-type malformations is principally neonatal perineoplasty, while that for intermediate- or high-type malformations is colostomy, followed by a pull-through operation during infancy. Posterior sagittal anorectoplasty or laparoscopy-assisted surgery has recently been accepted as alternative procedures. Fecal incontinence represents a devastating problem that often prevents a patient from becoming socially accepted and may cause serious psychological sequelae. One-third of adult patients with high- or intermediate-type malformations occasionally complain of fecal incontinence after surgery. Most patients with ARM have normal urinary function if they do not have urinary tract or sacral anomalies. These associated anomalies also influence the prognosis for sexual function, especially in males. Some female patients have experienced normal vaginal delivery and had children. In patients with cloacal malformation, however, fertility or sexual problems are also often present. Based on this information, it is clear that only well-planned and systemic treatments can provide a good functional prognosis after making a correct classification in the neonatal period.

Diagnostic impact of computed tomography cholangiography and magnetic resonance cholangiopancreatography on pancreaticobiliary maljunction.

BACKGROUND/PURPOSE: The aim of this study was to investigate the diagnostic potential of computed tomography cholangiography (CTC) and magnetic resonance cholangiopancreatography (MRCP) in children with pancreaticobiliary maljunction (PBM). METHODS: Fifty-three children with PBM were consecutively treated between 1997 and 2009. Among them, the patients who underwent CTC and/or MRCP preoperatively were enrolled in this study. Computed tomography cholangiography was examined after infusion of meglumine iodoxamate with subsequent 3-dimensional rendering. The visualization of the biliary and pancreatic duct systems was evaluated and compared with that visualized with MRCP. The findings of direct cholangiography were used as the standard of reference. RESULTS: Of the 53 cases with PBM, 17 cases were examined by CTC, 10 cases by MRCP, and 17 with both. The extrahepatic bile tract was visualized in 32 (94.1%) of 34 patients in CTC and in all 27 patients in MRCP. The intrahepatic bile duct was more frequently demonstrated by MRCP than by CTC (96.3% vs 70.6%, P = .02). Pancreaticobiliary maljunction was noted in 13 (38.2%) of 34 with CTC and in 12 (44.4%) of 27 with MRCP. The minimum age for visualization of PBM was at 10 months in CTC and at 1 year and 11 months in MRCP, respectively. The main pancreatic duct was more frequently visualized by MRCP than by CTC (81.5% vs 8.8%, P < .001). CONCLUSIONS: Magnetic resonance cholangiopancreatography provides superior visualization of the intrahepatic duct and the pancreatic system when compared with CTC. However, it is still challenging to perform a good-quality examination in young infant. The great advantage of CTC is its ability to produce high-quality images without respiratory artifacts and that it allows accurate assessment of the presence of PBM equivalent to MRCP.

Establishment of a rescue program for anorectal malformations induced by retinoic acid in mice.

AIMS OF STUDY: Retinoid-mediated signal transduction plays a crucial role in the embryogenesis of various organs. We previously reported the successful induction of anorectal malformations in mice using retinoic acid (RA). Retinoic acid controls the expression of essential target genes for cell differentiation, morphogenesis, and apoptosis through a complicated interaction in which RA receptors form heterodimers with retinoid X receptors. In the present study, we investigated whether the retinoid antagonist, LE135, could prevent the induction of anorectal malformations (ARMs) in mice. METHODS: Retinoic acid was intraperitoneally administered as 100 mg/kg of all-trans RA on E9; and then the retinoid antagonist, LE135, was intraperitoneally administered to pregnant ICR strain mice on the eighth gestational day (E8), 1 day before administration of RA (group B) or on E9, simultaneously (group C) with RA administration. All of the embryos were obtained from the uteri on E18. Frozen sections were evaluated for concentric layers around the endodermal epithelium by hematoxylin and eosin staining. RESULTS: In group A, all of the embryos demonstrated ARM with rectoprostatic urethral fistula, or rectocloacal fistula, and all of the embryos showed the absence of a tail. In group B, 36% of the embryos could be rescued from ARM. However, all of the rescued embryos had a short tail that was shorter than their hind limb. The ARM rescue rates in group B were significantly improved compared to those in group A (P < .01). In group C, 45% of the embryos were rescued from ARM, but all of the rescued embryos had short tail. The ARM rescue rate in group C was significantly improved compared to that in group A (P < .01). However, there was no significant difference in the ARM rescue rate between group B and Group C. CONCLUSION: The present study provides evidence that in the hindgut region, RAR selective retinoid antagonist, LE135, could rescue embryos from ARM. However, the disturbance of all-trans RA acid was limited to the caudal region. Further study to establish an appropriate rescue program for ARM in a mouse model might suggest a step toward protection against human ARM in the future.

Diagnosis and treatment of pancreaticobiliary maljunction in children.

Pancreaticobiliary maljunction (PBM), which may be called by synonymous terms such as "anomalous arrangement of the pancreaticobiliary duct" or "anomalous union of biliopancreatic ducts," is defined as an anatomical maljunction of the pancreatic duct and the biliary duct outside of the duodenal wall beyond the influence of the sphincter of Oddi. Pancreaticobiliary maljunction is classified into three groups according to the type of the pancreaticobiliary junction. Pancreaticobiliary maljunction is diagnosed mainly by endoscopic retrograde cholangiopancreatography; however, in pediatric patients, it may be diagnosed by intraoperative cholangiography, and more recently has been diagnosed by computed tomographic cholangiography or contrast-enhanced helical computed tomography. Children with PBM without choledochal cysts usually do not show any symptoms except for abdominal pain and hyperamylasemia. Pancreaticobiliary maljunction is considered to be a major risk factor for biliary tract malignancy. In patients with PBM, free reflux of pancreatic juice into the biliary tract might induce biliary tract damage and biliary carcinogenesis. Thus, total resection of the extrahepatic bile duct and hepaticojejunostomy are recommended in children diagnosed with PBM with choledochal cyst. Early diagnosis and early surgical treatment provide a good prognosis with few complications. In addition, successive follow-up is necessary for early detection of biliary tract malignancy, especially in patients demonstrating postoperative complications.

Left-right asymmetry in the level of active Nodal protein produced in the node is translated into left-right asymmetry in the lateral plate of mouse embryos.

Left-right (L-R) asymmetry in the mouse embryo is generated in the node and is dependent on cilia-driven fluid flow, but how the initial asymmetry is transmitted from the node to the lateral plate has remained unknown. We have now identified a transcriptional enhancer (ANE) in the human LEFTY1 gene that exhibits marked L>R asymmetric activity in perinodal cells of the mouse embryo. Dissection of ANE revealed that it is activated in the perinodal cells on the left side by Nodal signaling, suggesting that Nodal activity in the node is asymmetric at a time when Nodal expression is symmetric. Phosphorylated Smad2/3 (pSmad2) indeed manifested an L-R asymmetric distribution at the node, being detected in perinodal cells preferentially on the left side. This asymmetry in pSmad2 distribution was found to be generated not by unidirectional transport of Nodal but rather as a result of LR distribution of active Nodal in the node is translated into the asymmetry in LPM.

Implications of intestinal metaplasia of the gallbladder in children with pancreaticobiliary maljunction.

PURPOSE: Pancreaticobiliary maljunction (PBM) is associated with an increased frequency of gallbladder malignancy. Intestinal metaplasia is often observed in gallbladder disease and is a risk factor for gallbladder carcinoma in adults. The hyperplasia-dysplasia-carcinoma progression is one of the possible mechanisms involved in biliary carcinogenesis. In this study, we evaluate the gallbladders of children with PBM for intestinal metaplasia and other histological changes. METHODS: From January 1997 to July 2010, 45 children with PBM were treated at our institution. A total of 42 children were included in our analysis which included histology and medical record review. RESULTS: The median age was 2.9 years (range 1 month-16.5 years). The most common histological finding was villous-type mucosal hyperplasia, found in 24 patients (57.1%). Mucous gland metaplasia and goblet cell metaplasia were observed in 12 (28.6%) and 7 (16.7%) patients, respectively. There were no cases of malignancy. The intra-gallbladder amylase level in patients with mucosal hyperplasia was significantly elevated (81,373 ± 92,442 vs. 38,932 ± 61,466; p = 0.042). Patients with mucous gland metaplasia had significantly higher serum amylase levels (833 ± 1,214 vs. 343 ± 358; p = 0.024). CONCLUSION: The incidence of intestinal metaplasia is relatively high even in children with PBM. Such mucosal changes are related to cholangitis resulting from the regurgitation of pancreatic juice into the bile duct, which also causes hyperamylasemia via cholangio-venous reflux.

Laparoscopic versus open abdominoperineal rectoplasty for infants with high-type anorectal malformation.

BACKGROUND/PURPOSE: There has not been any study comparing laparoscopic abdominoperineal rectoplasty (ARP) with open ARP. This study investigated the true benefits of the laparoscopic approach in infants with high anorectal malformation. PATIENTS AND METHODS: A retrospective analysis was performed in 28 infants with high anorectal malformation treated between 1990 and 2007. Fifteen were treated by open ARP, and 13 were treated by laparoscopic ARP. Surgical durations, amount of bleeding, complications, anorectal pressure measurements, barium enema study, and clinical assessment were compared between the 2 groups. RESULTS: The amount of intraoperative bleeding was significantly less in laparoscopic ARP (12 ± 11 g) than in open ARP (65 ± 44 g) (P = .003). Anal resting pressure was 34 ± 9 cm H(2)O after laparoscopic ARP and 31 ± 14 cm H(2)O after open ARP. Anorectal reflex was positive in 1 (7%) of 15 after open ARP and 3 (23%) of 13 after laparoscopic ARP. There was no significant difference in barium enema study and clinical assessment between the 2 groups. With regard to postoperative complications, mucosal prolapse occurred in 10 (67%) of 15 after open ARP and in none of 13 after laparoscopic ARP (P = .003). CONCLUSION: Benefits of the laparoscopic approach were reduced intraoperative bleeding and a lower incidence of postoperative anal mucosal prolapse. These results indicate that minimal dissection of the mesorectum in laparoscopic ARP may provide those better outcomes.

OK-432 therapy for chylous pleural effusion or ascites associated with lymphatic malformations.

OK-432 therapy is effective for the treatment of macrocystic lymphatic malformations (LMs), but the optimal management of patients with microcystic LMs associated with large chylous pleural effusions or chylous ascites is not resolved. We performed thoracoscopic- or laparoscopic-guided injection of OK-432 for 2 patients with diffuse microcystic LMs accompanied by refractory chylous pleural effusion or chylous ascites. Both cases responded well to OK-432 therapy with improvement/resolution of fluid collections and associated symptoms. We recommend the use of OK-432 therapy as a promising treatment for microcystic LMs with functionally significant lymphatic fluid collections.

Usefulness of magnetic resonance imaging for congenital prepubic fistula.

Congenital prepubic fistula is a rare congenital anomaly. Complete removal of the fistular tract remains challenging because of the complicated course. Although conventional fistulography has been used widely as a diagnostic tool for congenital prepubic fistula, more detailed information such as accurate localization of the fistular end or relative position to the urinary tract cannot be preoperatively obtained because the conventional contrast studies have insufficient capability. In this article, we reported the complete removal of congenital prepubic fistula based on preoperative magnetic resonance imaging findings, especially T2-weighted imaging. Magnetic resonance imaging clearly displayed not only the tract of the prepubic fistula originating from a subcutaneous cyst but also the tract extending and ending near the top of the urinary bladder.

Predicting factors on the occurrence of cystic dilatation of intrahepatic biliary system in biliary atresia.

PURPOSE: Cystic dilatation of intrahepatic biliary system (CDIB) is an intractable complication of biliary atresia (BA). In this study, we investigated the predicting factors of CDIB development after jaundice resolved following hepatoportoenterostomy (HPE). METHODS: From 1988 to 2008, 28 (80.0%) of 35 uncorrectable type of BA patients became jaundice-free after HPE. Of these 28 patients, this retrospective study included comparisons of the preoperative characteristics, postoperative jaundice period, cumulative steroid dose, outcome, and liver fibrosis grade at the time of HPE between CDIB-positive and -negative groups, divided by postoperative ultrasonography findings. RESULTS: There were no differences between groups in perioperative characteristics. Liver fibrosis in the CDIB-positive group (n = 7) included grade II in two patients, grade III in four patients, and grade IV in one patient. On the contrary, the CDIB-negative group (n = 21) included 8, 11, 2, and 0 patients with grades I-IV, respectively, with a significant difference (p < 0.05) between groups. Survival rate with native liver in CDIB-positive group was significantly lower than that in CDIB-negative group (p < 0.05). CONCLUSION: Postoperative CDIB might be a poor prognostic factor, and the liver fibrosis grade at the time of HPE could be helpful to predict the development of CDIB after HPE.

Long-term outcomes after hepaticojejunostomy for choledochal cyst: a 10- to 27-year follow-up.

INTRODUCTION: Choledochal cyst (CC) is closely associated with anomalous arrangement of the pancreaticobiliary duct, which is considered a high-risk factor for biliary tract malignancy. Early diagnosis and early treatment for CC could lead to a good prognosis. This study investigated late complications and long-term outcomes after surgery for CC. PATIENTS AND METHODS: Fifty-six patients with CC and over 10 years of postoperative follow-up were analyzed retrospectively. All patients had undergone total resection of the extrahepatic bile duct and hepaticojejunostomy. RESULTS: Six patients showed liver dysfunction manifested in the first 10 years after surgery, but all returned to normal thereafter. Dilatation of intrahepatic bile ducts persisted in 6 postoperatively, and in 3, this was still apparent more than 10 years after. Recurrent abdominal pain was encountered in 3, 1 had pancreas divisum with a pancreatic stone, and 1 had adhesive small bowel obstruction. Two patients developed biliary tract malignancy. A 14-year-old girl died of recurrent common bile duct cancer 2 years after the initial resection of CC with adenocarcinoma. A 26-year-old man with repeated cholangitis owing to multiple intrahepatic bile stones developed cholangiocarcinoma 26 years after the initial resection of CC. Event-free survival rate and overall survival rate were 89% (50/56) and 96% (54/56), respectively. CONCLUSIONS: Choledochal cyst generally has an excellent prognosis with early total resection and reconstruction. Long-term surveillance for the development of malignancy is still essential, especially if there is ongoing dilatation of the intrahepatic bile duct or biliary stones.

Management strategies for infants with total intestinal aganglionosis.

PURPOSE: This study investigated appropriate management strategies for infants with total intestinal aganglionosis (TIA), focusing on surgical and medical managements. METHODS: Six infants with TIA or near TIA treated in our institution between 1980 and 2007 were reviewed retrospectively. Surgery was performed as a simple jejunostomy, 65 to 70 cm below the ligament of Treitz (LOT) in 2 infants, and 30 cm below LOT in 1 without extended myectomy-myotomy (EMM). Jejunostomy with EMM 30 to 35 cm below LOT were performed in 3. RESULTS: Two infants with jejunostomy 65 cm or 70 cm distal from LOT died of sepsis at 7 months and 8 months of age, respectively. One infant with jejunostomy 30 cm from LOT without EMM died of cholestatic liver failure at the age of 1 year and 8 months. To date, the remaining 3 infants with jejunostomy 30 cm or 35 cm distal from LOT in addition to EMM have survived 10 years, 3 years and 10 months, and 2 years of age, respectively. Nutritional managements such as parenteral nutrition with 80 to 100 kcal/kg/day and oral feeding with elemental diet (ED) were preferable to reduce the occurrence of enteritis, sepsis, and cholestatic liver dysfunction. CONCLUSION: A good combination of cyclic parenteral nutrition and oral intake with elemental diet after short proximal jejunostomy with EMM may be a key for the survival of infants with TIA. In addition, in infants whose absorptive function was not ameliorated by EMM, medical management such as GH administration might be worth trying.

Bombesin can minimize impairments of interstitial cells of Cajal induced by FK506 in small bowel transplantation.

PURPOSE: Interstitial cells of Cajal (ICC) are known as intestinal pacemaker cells and express c-kit on their membrane. Previously, we reported that FK506 had neurotoxicity to enteric ganglia, and bombesin (BBS) preserved them against FK506. The aim of this study was to investigate whether ICC was impaired by FK506 and whether ICC was preserved by BBS against FK506. METHODS: Twelve rats underwent allogeneic SBTx heterotopically and were divided into 2 groups as follows: group A underwent SBTx with FK506 and group B with FK506/BBS. All rats were administered FK506 daily. Either BBS or normal saline was infused continuously from day 14 to 28. Analysis of ICC was performed immunohistochemically with c-kit. Interstitial cells of Cajal were evaluated by counting the number of c-kit-positive clusters in each graft. RESULTS: The expression of c-kit accumulated around 60% of PGP9.5-positive enteric ganglia. The number of c-kit-positive clusters in group A was 22.3 +/- 5.5 clusters per cross section (C/CS) and that in group B was 36.3 +/- 5.1 C/CS. Interstitial cells of Cajal were well preserved in group B. There was a significant difference between groups A and B (P <.001). CONCLUSION: Interstitial cells of Cajal were impaired by FK506 in allografts, and BBS could minimize the impairment of ICC against FK506.