Age-specific nasal epithelial responses to SARS-CoV-2 infection.

Children infected with SARS-CoV-2 rarely progress to respiratory failure. However, the risk of mortality in infected people over 85 years of age remains high. Here we investigate differences in the cellular landscape and function of paediatric (<12 years), adult (30-50 years) and older adult (>70 years) ex vivo cultured nasal epithelial cells in response to infection with SARS-CoV-2. We show that cell tropism of SARS-CoV-2, and expression of ACE2 and TMPRSS2 in nasal epithelial cell subtypes, differ between age groups. While ciliated cells are viral replication centres across all age groups, a distinct goblet inflammatory subtype emerges in infected paediatric cultures and shows high expression of interferon-stimulated genes and incomplete viral replication. In contrast, older adult cultures infected with SARS-CoV-2 show a proportional increase in basaloid-like cells, which facilitate viral spread and are associated with altered epithelial repair pathways. We confirm age-specific induction of these cell types by integrating data from in vivo COVID-19 studies and validate that our in vitro model recapitulates early epithelial responses to SARS-CoV-2 infection.

Engineered Tissue-Stent Biocomposites as Tracheal Replacements.

Here we report the creation of a novel tracheal construct in the form of an engineered, acellular tissue-stent biocomposite trachea (TSBT). Allogeneic or xenogeneic smooth muscle cells are cultured on polyglycolic acid polymer-metal stent scaffold leading to the formation of a tissue comprising cells, their deposited collagenous matrix, and the stent material. Thorough decellularization then produces a final acellular tubular construct. Engineered TSBTs were tested as end-to-end tracheal replacements in 11 rats and 3 nonhuman primates. Over a period of 8 weeks, no instances of airway perforation, infection, stent migration, or erosion were observed. Histological analyses reveal that the patent implants remodel adaptively with native host cells, including formation of connective tissue in the tracheal wall and formation of a confluent, columnar epithelium in the graft lumen, although some instances of airway stenosis were observed. Overall, TSBTs resisted collapse and compression that often limit the function of other decellularized tracheal replacements, and additionally do not require any cells from the intended recipient. Such engineered TSBTs represent a model for future efforts in tracheal regeneration.

Thyroid Surgery in Children: Clinical Outcomes.

AIM: The aim of this study was to review the outcomes of thyroid surgery in children operated for both benign and malignant conditions. PATIENTS AND METHOD: Demography, clinical features, and surgical outcomes were noted retrospectively for operations performed during the last 23 years. Results were analyzed using Fisher exact test and Woolf (logit) method with p value < 0.05 considered as significant. RESULTS: In total, 61 children (43 girls and 18 boys) underwent thyroidectomy for benign (70%) and malignant (30%) conditions. Median follow-up period was 1.4 years. In the benign group, 84% children had Graves disease and 16% had other conditions. In this study, 42% children had total, 22% had near-total, 27% had subtotal, and 9% had type 2 hemithyroidectomy. In the malignant group, 50% had multiple endocrine neoplasia, 33% had papillary, 11% had follicular cancer, and 6% had B-cell lymphoma. Fifty percent children had prophylactic thyroidectomy, 44% had total thyroidectomy plus lymphadenectomy, and 6% had hemithyroidectomy. At the time of surgery, children with benign conditions were older than those with malignancy (median, 12 vs. 7.5 years). There were no incidents of postoperative bleeding or infection. Hypocalcemia was significantly more frequent in the malignant group (39 vs. 9%, p value = 0.01). The type of recurrent laryngeal nerve (RLN) injury was more serious in the benign group (one bilateral and one unilateral permanent injury) than in the malignant group (transient hoarseness in three). Overall rate of complications was higher for operations for malignancy (56 vs. 28%, p value = 0.07). In Graves disease, the subtotal thyroidectomies had a recurrence of 30% but no recurrence was seen following total or near-total thyroidectomy group (p value = 0.01). There was no recurrence in the malignant group. Children operated after 2000 were younger than those operated before 2000 (median age, 9 vs. 14 years). Malignant conditions were more common in children operated after 2000 in comparison to before 2000 (55 vs. 10%). CONCLUSION: Benign conditions are commonest indications for thyroid surgery in children but the incidence of surgery for malignant conditions is rising. Overall rate of complications, especially hypocalcemia, is higher after surgery for malignancy but all cases of permanent RLN injury were in benign group. Total or near total thyroidectomy prevents recurrence of thyrotoxicosis and is an operation of choice for Graves disease.

Paediatric laparoscopic Heller's cardiomyotomy: a single centre series.

BACKGROUND: The optimal management of oesophageal achalasia remains unclear in the paediatric population due to the rarity of the disease. This study reviews the institutional experience of the laparoscopic Heller's cardiomyotomy (HC) procedure and attempts to define the most appropriate treatment. METHODS: A retrospective review of children undergoing HC at a single institution was performed. Demographics, pre-operative investigations, and interventions were reviewed. Post-operative outcomes and follow up were evaluated. Data is expressed as median (range). RESULTS: Twenty-eight children were included (13 male, 15 female) whose median age was 13 (3.2-17.4) years. Nine children underwent a pre-operative oesophageal balloon dilatation (OBD) a median of 1(1-6) times. Others included botulinum toxin injection (n=1) and Nifedipine (n=1). All had a pre-operative upper gastrointestinal contrast series, and twenty-five had upper gastrointestinal endoscopy and manometry. All had laparoscopic HC with no conversions, and ten had a concomitant fundoplication. Post-operative intervention occurred in eight (28%) incorporating OBD (n=7), of whom four required a redo HC. One patient underwent a redo without intervening OBD. Follow-up was for a median of 0.83 (0-5) years with fourteen children discharged from surgical follow-up. Twenty-seven have thus far had a good outcome. CONCLUSION: This study comprises the largest series of paediatric laparoscopic HC reported to date. It is effective with or without a fundoplication and is the best long term treatment modality available. OBD for persisting symptoms following HC may obviate the need for redo myotomy.

Novel exomphalos genetic mouse model: the importance of accurate phenotypic classification.

BACKGROUND: Rodent models of abdominal wall defects (AWD) may provide insight into the pathophysiology of these conditions including gut dysfunction in gastroschisis, or pulmonary hypoplasia in exomphalos. Previously, a Scribble mutant mouse model (circletail) was reported to exhibit gastroschisis. We further characterise this AWD in Scribble knockout mice. METHOD: Homozygous Scrib knockout mice were obtained from heterozygote matings. Fetuses were collected at E17.5-18.5 with intact amniotic membranes. Three mutants and two control fetuses were imaged by in amnio micro-MRI. Remaining fetuses were dissected, photographed and gut length/weight measured. Ileal specimens were stained for interstitial cells of Cajal (ICC), imaged using confocal microscopy and ICC quantified. RESULTS: 127 fetuses were collected, 15 (12%) exhibited AWD. Microdissection revealed 3 mutants had characteristic exomphalos phenotype with membrane-covered gut/liver herniation into the umbilical cord. A further 12 exhibited extensive AWD, with eviscerated abdominal organs and thin covering membrane (intact or ruptured). Micro-MRI confirmed these phenotypes. Gut was shorter and heavier in AWD group compared to controls but morphology/number of ICC was not different. DISCUSSION: The Scribble knockout fetus exhibits exomphalos (intact and ruptured), in contrast to the original published phenotype of gastroschisis. Detailed dissection of fetuses is essential ensuring accurate phenotyping and result reporting.