Noninvasive graft monitoring using donor-derived cell-free DNA in Japanese liver transplantation.

AIM: To evaluate the use of donor-derived cell-free DNA (dd-cfDNA) in diagnosing graft injuries in Japanese liver transplantation (LTx), including family-related living donors. METHODS: A total of 321 samples from 10 newly operated LTx recipients were collected to monitor the early dynamics of dd-cfDNA levels after LTx. Fifty-five samples from 55 recipients were collected during protocol biopsies (PB), whereas 36 samples from 27 recipients were collected during event biopsies, consisting of 11 biopsy-proven acute rejection (AR), 20 acute dysfunctions without rejection (ADWR), and 5 chronic rejections. The levels of dd-cfDNA were quantified using a next-generation sequencer based on single nucleotide polymorphisms. RESULTS: The dd-cfDNA levels were elevated significantly after LTx, followed by a rapid decline to the baseline in patients without graft injury within 30 days post-LTx. The dd-cfDNA levels were significantly higher in the 11 samples obtained during AR than those obtained during PB (p < 0.0001), which decreased promptly after treatment. The receiver operator characteristic curve analysis of diagnostic ability yielded areas under the curve of 0.975 and 0.897 for AR (rejection activity index [RAI] ≥3) versus PB and versus non-AR (ADWR + PB). The dd-cfDNA levels during AR were elevated earlier and correlated more strongly with the RAI (r = 0.740) than aspartate aminotransferase/alanine aminotransferase. The dd-cfDNA levels were neither associated with graft fibrosis based on histology nor the status of donor-specific antibodies in PB samples. CONCLUSIONS: Donor-derived cell-free DNA serves as a sensitive biomarker for detecting graft injuries in LTx. Further large-scale cohort studies are warranted to optimize its use in differentiating various post-LTx etiologies.

Factors predicting surgical difficulties in congenital biliary dilatation in pediatric patients.

BACKGROUND: The effects of disease classification and the patient's preoperative condition on the difficulty of performing a laparotomy for pediatric congenital biliary dilatation (CBD) have not been fully elucidated. METHODS: The present study retrospectively analyzed 46 pediatric CBD laparotomies performed at the study center between March 2010 and December 2021 and predictors of operative time. The patients were separated into a short operative time group (SOT) (≤ 360 min, n = 27) and a long operative time group (LOT) (> 360 min, n = 19). RESULTS: The preoperative AST and ALT values were higher, and the bile duct anastomosis diameter was larger, in the LOT. Correlation analysis demonstrated that the maximum cyst diameter, preoperative neutrophil-to-lymphocyte ratio, AST, ALT, AMY, and bile duct anastomosis diameter correlated positively with operative time. Multivariate analysis identified the maximal cyst diameter, preoperative AST, and bile duct anastomosis diameter as significant factors affecting surgical time. Postoperatively, intrapancreatic stones and paralytic ileus were observed in one patient each in the SOT, and mild bile leakage was observed in one patient in the LOT. CONCLUSIONS: The maximum cyst diameter, preoperative AST, and bile duct anastomosis diameter have the potential to predict the difficulty of performing a pediatric CBD laparotomy.

Experimental evidence for the correlation between RNA structural fluctuations and the frequency of beneficial mutations.

RNA has been used as a model molecule to understand the adaptive evolution process owing to the simple relationship between the structure (i.e., phenotype) and sequence (i.e., genotype). RNA usually forms multiple substructures with similar thermodynamic stabilities, called structural fluctuations. Ancel and Fontana theoretically proposed that structural fluctuation is directly related to the ease of change in structures by mutations and thus works as a source of adaptive evolution; however, experimental verification is limited. Here, we analyzed 76 RNA genotypes that appeared in our previous in vitro evolution to examine whether (i) RNA fluctuation decreases as adaptive evolution proceeds and (ii) RNAs that have larger fluctuations tend to have higher frequencies of beneficial mutations. We first computationally estimated the structural fluctuations of all RNAs and observed that they tended to decrease as their fitness increased. We next measured the frequency of beneficial mutations for 10 RNA genotypes and observed that the total number of beneficial mutations was correlated with the size of the structural fluctuations. These results consistently support the idea that the structural fluctuation of RNA, at least those evaluated in our study, works as a source of adaptive evolution.

Simulated slide tracheoplasty for congenital tracheal stenosis using three-dimensional printed models.

PURPOSE: The slide tracheoplasty (STP) is the standard treatment for severe congenital tracheal stenosis (CTS). Understanding the features of the tracheal stenosis in each case and choosing an appropriate incision design are very important for successfully executing the procedure. The present study aimed to evaluate the advantages of three-dimensional (3D) printed models of the trachea for improving CTS. METHODS: Three-D tracheal models were created using computed tomography (CT) data from ten patients undergoing STP for CTS. Simulated surgery was performed using the hollow models after reinforcing with them with a coating of gum spray. Clinical outcomes, including patient survival, postoperative surgical interventions, and time required for STP, were compared with the corresponding values in the last ten patients before the introduction of 3D model simulations. RESULTS: All ten patients for whom simulated surgery using a 3D tracheal model were conducted achieved good airway patency after their STP. The surgeons reported feeling that the 3D model simulations were highly effective although there was no significant difference in the clinical outcomes of the groups with or without simulated STP. The models were useful not only for surgical planning but also for sharing important information among the multidisciplinary team and the patients' family. CONCLUSION: Our experience using 3D tracheal models demonstrated several features enabling improvement in the surgical treatment of CTS.

Outcomes of slide tracheoplasty for congenital tracheal stenosis in 80 children: A 22-year single-center experience.

PURPOSE: The application of slide tracheoplasty (STP) in the treatment of congenital tracheal stenosis (CTS) has improved patient outcomes over the past few decades. We reviewed our experiences with the procedure, elucidated risk factors, and discussed important aspects of perioperative management to improve outcomes. METHOD: Patients with CTS undergoing STP between July 1998 and December 2020 were enrolled. Patient characteristics, perioperative condition, management, operative details, and outcomes, including mortality and postoperative intervention, were collected from medical records. RESULTS: Eighty patients underwent STP. Sixty-five patients (81.3%) had an associated cardiovascular anomaly. Thirteen patients (16.3%) had unilateral lung agenesis or hypoplasia. Preoperative mechanical ventilation was necessary in 54 (67.5%) patients, and extracorporeal membrane oxygenation (ECMO) was required in eight patients (10.0%). An endotracheal tube was placed before the stenotic entrance to avoid granulation. During STP, the trachea was dissected as little as possible to maintain the blood supply. The one-year survival rate was 88.8% (nine patients died). One patient (1.3%) required postoperative balloon dilation, and none required stenting or granulation removal. Of the survivors, 62 (92.5%) achieved successful extubation without tracheostomy. Multivariable analysis revealed complex cardiovascular anomaly (P = 0.05) and preoperative ECMO (P = 0.019) to be adverse predictors of survival. CONCLUSION: Although STP can be performed successfully in CTS patients, surgeons and families should be aware of factors that may lead to a more difficult postoperative course or increase the mortality. Meticulous, perioperative positioning of the endotracheal tube and preserving the tracheal blood flow can minimize the need for postoperative intervention.

Establishment and characterization of Neu1-knockout zebrafish and its abnormal clinical phenotypes.

Mammalian sialidase Neu1 is involved in various physiological functions, including cell adhesion, differentiation, cancer metastasis, and diabetes through lysosomal catabolism and desialylation of glycoproteins at the plasma membrane. Various animal models have been established to further explore the functions of vertebrate Neu1. The present study focused on zebrafish (Danio rerio) belonging to Cypriniformes as an experimental animal model with neu1 gene deficiency. The results revealed that the zebrafish Neu1 desialyzed both α2-3 and α2-6 sialic acid linkages from oligosaccharides and glycoproteins at pH 4.5, and it is highly conserved with other fish species and mammalian Neu1. Furthermore, Neu1-knockout zebrafish (Neu1-KO) was established through CRISPR/Cas9 genome editing. Neu1-KO fish exhibited slight abnormal embryogenesis with the accumulation of pleural effusion; however, no embryonic lethality was observed. Although Neu1-KO fish were able to be maintained as homozygous, they showed smaller body length and weight than the wild-type (WT) fish, and muscle atrophy and curvature of the vertebra were observed in adult Neu1-KO fish (8 months). The expression patterns of myod and myog transcription factors regulating muscle differentiation varied between Neu1-KO and WT fish embryo. Expression of lysosomal-related genes, including ctsa, lamp1a, and tfeb were up-regulated in adult Neu1-KO muscle as compared with WT. Furthermore, the expression pattern of genes involved in bone remodeling (runx2a, runx2b, and mmp9) was decreased in Neu1-KO fish. These phenotypes were quite similar to those of Neu1-KO mice and human sialidosis patients, indicating the effectiveness of the established Neu1-KO zebrafish for the study of vertebrate Neu1 sialidase.