Normal skeletal pattern formation in chick limb bud with a mesenchymal hole is mediated by adjustment of cellular properties along the anterior-posterior axis in the limb bud.

The chick limb bud has plasticity to reconstruct a normal skeletal pattern after a part of mesenchymal mass is excised to make a hole in its early stage of development. To understand the details of hole closure and re-establishment of normal limb axes to reconstruct a normal limb skeleton, we focused on cellular and molecular changes during hole repair and limb restoration. We excised a cube-shaped mass of mesenchymal cells from the medial region of chick hindlimb bud (stage 23) and observed the following morphogenesis. The hole had closed by 15 â€‹h after excision, followed by restoration of the limb bud morphology, and the cartilage pattern was largely restored by 48 â€‹h. Lineage analysis of the mesenchymal cells showed that cells at the anterior and posterior margins of the hole were adjoined at the hole closure site, whereas cells at the proximal and distal margins were not. To investigate cell polarity during hole repair, we analyzed intracellular positioning of the Golgi apparatus relative to the nuclei. We found that the Golgi apparatus tended to be directed toward the hole among cells at the anterior and posterior margins but not among cells at identical positions in normal limb buds or cells at the proximal and distal hole margins. In the manipulated limb buds, the frequency of cell proliferation was maintained compared with the control side. Tbx3 expression, which was usually restricted to anterior and posterior margins of the limb bud, was temporarily expanded medially and then reverted to a normal pattern as limb reconstruction proceeded, with Tbx3 negative cells reappearing in the medial regions of the limb buds. Thus, mesenchymal hole closure and limb reconstruction are mainly mediated by cells at the anterior and posterior hole margins. These results suggest that adjustment of cellular properties along the anteroposterior axis is crucial to restore limb damage and reconstruct normal skeletal patterns.

Changes in Metabolomic Profiles Induced by Switching from an Erythropoiesis-Stimulating Agent to a Hypoxia-Inducible Factor Prolyl Hydroxylase Inhibitor in Hemodialysis Patients: A Pilot Study.

Hypoxia-inducible factor prolyl hydroxylase inhibitors (HIF-PHIs) are a new class of medications for managing renal anemia in patients with chronic kidney disease (CKD). In addition to their erythropoietic activity, HIF-PHIs exhibit multifaceted effects on iron and glucose metabolism, mitochondrial metabolism, and angiogenesis through the regulation of a wide range of HIF-responsive gene expressions. However, the systemic biological effects of HIF-PHIs in CKD patients have not been fully explored. In this prospective, single-center study, we comprehensively investigated changes in plasma metabolomic profiles following the switch from an erythropoiesis-stimulating agent (ESA) to an HIF-PHI, daprodustat, in 10 maintenance hemodialysis patients. Plasma metabolites were measured before and three months after the switch from an ESA to an HIF-PHI. Among 106 individual markers detected in plasma, significant changes were found in four compounds (erythrulose, n-butyrylglycine, threonine, and leucine), and notable but non-significant changes were found in another five compounds (inositol, phosphoric acid, lyxose, arabinose, and hydroxylamine). Pathway analysis indicated decreased levels of plasma metabolites, particularly those involved in phosphatidylinositol signaling, ascorbate and aldarate metabolism, and inositol phosphate metabolism. Our results provide detailed insights into the systemic biological effects of HIF-PHIs in hemodialysis patients and are expected to contribute to an evaluation of the potential side effects that may result from long-term use of this class of drugs.

Pathological findings of progressive renal involvement in a patient with TAFRO syndrome.

TAFRO syndrome (thrombocytopenia, anasarca, fever, reticulin fibrosis, and organomegaly) is thought of as an atypical type of idiopathic multicentric Castleman's disease. Interleukin-6, vascular endothelial growth factor (VEGF), and other cytokines are considered etiological factors. A 45-year-old woman was admitted to hospital with unknown fever and abdominal pain. She had thrombocytopenia, anasarca, proteinuria/hematuria, and slight hepatosplenomegaly. Based on her clinical course and laboratory data, she was diagnosed as having TAFRO syndrome. Kidney biopsy showed a membranoproliferative glomerulonephritis (MPGN)-like lesion containing lobulations of glomeruli, endothelial cell swelling, double contours of the glomerular basement membrane, and mesangiolysis. She was treated with methylprednisolone pulse (500 mg/day) and oral prednisolone (60 mg/day) therapy. The pleural effusion and ascites disappeared, and renal function normalized. Cyclosporine was added to prevent relapse. She went home, with no relapse 8 months after hospitalization. MPGN-like lesions were found frequently in patients with TAFRO syndrome in recent reports. However, there are few reports of pathologically confirmed cases of progressive renal involvement in TAFRO syndrome. The relationship between VEGF expression in renal tissue and the pathogenesis of renal injury in TAFRO syndrome was investigated in the present case.