Identification and characterization of myeloid cells localized in the tadpole liver cortex in Xenopus laevis.

In the present study, using transgenic frogs that express GFP specifically in myeloid cells under the myeloperoxidase enhancer sequence, we found that myeloperoxidase-positive cells are localized in the liver cortex at the late tadpole stages. Immunohistochemical analysis revealed that myelopoiesis in the liver cortex became evident after st. 50 and reached its peak by st. 56. Transplantation experiments indicated that cells with a high density at the liver cortex were derived from the dorso-lateral plate tissue in the neurula embryo. Analysis of smear samples of the cells isolated from collagenase-treated liver tissues of the transgenic tadpoles indicated that myeloid cells were the major population of blood cells in the larval liver and that, in addition to myeloid colonies, erythroid colonies expanded in entire liver after metamorphosis. Cells that were purified from the livers of transgenic tadpoles according to the GFP expression exhibited the multi-lobed nuclei. The results of present study provide evidence that the liver cortex of the Xenopus tadpole is a major site of granulopoiesis.

Congenital anaemia associated with loss-of-function variants in DNA polymerase epsilon 1.

DNA polymerase epsilon (Pol ε), a component of the core replisome, is involved in DNA replication. Although genetic defects of Pol ε have been reported to cause immunodeficiency syndromes, its role in haematopoiesis remains unknown. Here, we identified compound heterozygous variants (p.[Asp1131fs];[Thr1891del]) in POLE, encoding Pol ε catalytic subunit A (POLE1), in siblings with a syndromic form of severe congenital transfusion-dependent anaemia. In contrast to Diamond-Blackfan anaemia, marked reticulocytopenia or marked erythroid hypoplasia was not found. Their bone marrow aspirates during infancy revealed erythroid dysplasia with strongly positive TP53 in immunostaining. Repetitive examinations demonstrated trilineage myelodysplasia within 2 years from birth. They had short stature and facial dysmorphism. HEK293 cell-based expression experiments and analyses of patient-derived induced pluripotent stem cells (iPSCs) disclosed a reduced mRNA level of Asp1131fs-POLE1 and defective nuclear translocation of Thr1891del-POLE1. Analysis of iPSCs showed compensatory mRNA upregulation of the other replisome components and increase of the TP53 protein, both suggesting dysfunction of the replisome. We created Pole-knockout medaka fish and found that heterozygous fishes were viable, but with decreased RBCs. Our observations expand the phenotypic spectrum of the Pol ε defect in humans, additionally providing unique evidence linking Pol ε to haematopoiesis.

A myeloperoxidase enhancer drives myeloid cell-specific labeling in a transgenic frog line.

We have identified a myeloid cell-specific enhancer in the 5' flanking region of the Xenopus tropicalis myeloperoxidase gene. Transgenic reporter analysis using Xenopus laevis revealed that the expression of GFP was detected in the tail fin macrophages of a swimming tadpole, and the distributions of the GFP-positive and XL-2 (a pan-marker for leukocytes)-positive cells were mostly overlapping. The GFP-positive cells in the liver of the transgenic tadpole were localized in the same areas where the myeloid cells were present. Isolation of leukocytes from the peripheral blood cells followed by flow cytometric analysis revealed that the GFP-positive fraction was specifically enriched in neutrophils with lobulated nuclei. Furthermore, the macrophages purified from the peritoneal cavity were also GFP-positive. In summary, a transgenic frog line in which the myeloid cells are labeled with GFP provides a useful tool to elucidate the physiological role of myeloid cells of multiple origins in the embryo.

Use of Cervical Ultrasonography in Globus Sensation Investigation: A Retrospective Cohort Study.

BACKGROUND: A globus sensation is one of the most common complaints in otolaryngological practice. Patients with no associated abnormalities detected during the usual examinations performed in ENT clinics, are being diagnosed with globus sensation. Cervical ultrasonography is usually not performed in ENT clinics; however, it is useful in screening diseases of the subcutaneous tissue/organs, whose detection is not possible with the routine ENT examinations. The purpose of our study was to elucidate whether cervical ultrasound examination identifies abnormalities in patients with globus sensation. METHODS: A single-centre retrospective cohort study. Cervical ultrasonographic examinations were performed on patients with globus sensation at the Department of Otolaryngology, Head and Neck Surgery of Tottori university hospital, a tertiary care centre, from January 2013 to September 2017. The subjects were 74 patients who complained of globus sensation with no abnormality in general otolaryngological examination including laryngoscopy. RESULTS: Ultrasonography detected structural abnormalities in 60.8% of the patients with globus sensation: thyroid disorders in 41 patients, including: 35 patients with thyroid nodules, 4 patients with Hashimoto's disease, 1 patient with Grave's disease, and 1 patient with subacute thyroiditis; Sjögren syndrome in 2 patients; and cervical lipoma in 1 patient. Furthermore, 2 patients with thyroid disorders had concomitant esophageal cancer. CONCLUSION: Cervical ultrasonography identified thyroid disorders in patients with globus sensation, despite the normal ENT status. Therefore, it would be appropriate to adopt cervical ultrasonography as a routine examination at ENT clinics for patients with globus sensation.

Natural History of Exophytic Type Gastrointestinal Stromal Tumor: A Case Report.

Gastrointestinal stromal tumor (GIST) is the most common submucosal tumor of the stomach. GISTs are often detected by esophagogastroduodenal endoscopy. We have previously reported on endoscopically invisible medium-sized exophytic type GISTs. We present here a case of small exophytic GIST detected by transabdominal ultrasonography (TUS) in which the natural history of the tumor could be traced retrospectively through incidental findings obtained during follow-up for intraductal papillary mucinous neoplasm by magnetic resonance of imaging or computed tomography over about 10 years. The tumor appeared 7 years before its detection, and the doubling time was calculated as 6.9 years. In conclusion, low-risk exophytic GIST was estimated to have taken at least about 7 years to reach a size detectable by TUS.

Decreased Wave V Amplitude in Auditory Brainstem Responses of Children with Cerebellar Lesions.

BACKGROUND: This study aims to elucidate the effect of isolated cerebellar lesions sparing the brainstem on the auditory brainstem responses in children. METHODS: We enrolled 10 children (aged 1-16 years) with cerebellar lesions on neuroimaging but lacking clinical brainstem involvement signs and with normal brainstem volumes on magnetic resonance imaging. RESULTS: The interpeak latency of waves I and V was normal in 9 patients and was marginally prolonged in 1 patient. While amplitudes of waves I and III were normal, we noted a decreased amplitude of wave V and/or an increased I/V amplitude ratio in 6 patients; these included 5 of 8 patients with cerebellar hypoplasia/atrophy and 1 patient with acute cerebellar ataxia. CONCLUSION: Our results support the hypothesis of an inhibitory input from the cerebellar fastigial nucleus on the inferior colliculus, which might be disinhibited because of Purkinje cells dysfunction due to cerebellar cortex lesions, especially within the cerebellar vermis.