Expression of TGF-α, EGF and their common receptor in human fetal kidney

Summary: Transforming growth factor-α (TGF-α) and epidermal growth factor (EGF) are structurally related mitogenic polypeptides. They share the same receptor; EGF receptor. the EGF receptor is widely expressed in human fetal tissues including the kidney, but little is known about the role of TGF-α/EGF/EGF receptor system in human fetal kidney. the expression of TGF-α, EGF and their common receptor was investigated immunohistochemically in the human fetal kidneys. In the cortex, immunoreactivity for TGF-α was found in the differentiating proximal tubules. In contrast, immunoreactivity for EGF was present in the thick ascending limbs of the Henle's loop (TAL) and medullary collecting duct cells (CD). Immunoreactivity for their common receptor was present mainly in the TAL and medullary CD. These data support the assumption that the system of TGF-α, EGF and its receptor has an important role in the proliferation and differentiation of the TAL and medullary CD. the different localization of TGF-α and its receptor may indicate that TGF-α acts through a paracrine mechanism. the co-localization of EGF and its receptor in the TAL and medullary CD suggests that EGF may act as an autocrine growth factor.     

Plasma thrombopoietin level and platelet indices in hemodialysis patients receiving recombinant human erythropoietin

We focused on thrombocytopenia in hemodialysis patients (HD) receiving recombinant human erythropoietin (rHuEPO) and investigated thrombopoietin (TPO) level and platelet indices. We analyzed platelet parameters including mean platelet volume (MPV), platelet-crit (PCT), mean platelet component (MPC) concentration and platelet count (PLT) using ADVIA 2120 in 375 HD patients. This study included 25 HD patients undergoing treatment with rHuEPO at 9000 IU/week. These patients were divided into two groups by reference PLT of 130 × 10⁹/l [eight patients with low PLT (L-PLT group) and 17 patients with normal PLT (N-PLT group)], and TPO level and platelet indices in each group were compared with those in nine HD patients not receiving rHuEPO. In HD patients, the mean value of MPV was slightly higher and the mean values of PLT, PCT, and MPC were significantly lower than those in healthy controls. TPO levels were significantly higher in patients receiving rHuEPO than in patients not receiving rHuEPO. However, no significant difference was found between TPO levels in patients in the L-PLT group and patients in the N-PLT group. TPO levels were not correlated with PLT in these patients and that MPC levels decreased remarkably regardless of PLT.     

INSULIN AND GLUCAGON SECRETION IN HEPATIC GLYCOGENOSES

ABSTRACT. Okada, S., Seino, V., Kodama, H., Yutaka, T., Inui, K., Ishida, M., Yabuuchi, H. and Seino, Y. (Department of Pediatrics, Osaka University Hospital, Fukushima-ku, Osaka and The Third Division, Department of Medicine, University of Kobe, Kobe, Japan). Insulin and glucagon secretion in hepatic glycogenoses. Acta Paediatr Scand 68: 735, 1979.—Insulin and glucagon secretion was investigated in ten patients with hepatic glycogenosis, types I and III, in order to understand the relationship between hypoglycemia and pancreatic function. In all patients, both oral glucose tolerance and intravenous arginine infusion tests revealed hypoinsulinemia. Decreased urinary C-peptide levels with standard food intake also supported hypofunction of pancreatic beta cells. On the contrary, the normal secretion pattern of glucagon in both types indicated in the arginine loading test, intact alpha cells in the pancreas. Persistent hypoinsulinism, which is apparently an adaptation to hypoglycemia, could be an important cause of nutritional dwarfism in both types of glycogenosis. The usefulness of the measurement of urinary C-peptide, which evaluates the pancreatic function and provides management for normal body growth, is discussed.     

LEVELS OF VITAMIN D-METABOLITES IN A CASE OF ACRO-OSTEOLYSIS SYNDROME

ABSTRACT. On the initial examinations of a 17-year-old boy with acro-osteolysis syndrome, the levels of serum 25-hydroxycholecalciferol (25OHD) were low, whereas serum levels of 1,25-dihydroxycholecalciferol (1,25(OH)₂D) were normal. Administration of 1α-hydroxycholecalciferol (1OHD) failed to improve the osteoporosis, although the serum 25OHD level rose to normal. It is unlikely that impaired bone remodeling due to abnormal vitamin D-metabolism was a primary defect in our patient.     

Medical management and complications of X-linked hypophosphatemic vitamin D resistant rickets

To improve the growth failure, bowed legs, and biochemical and radiological abnormalities in patients with X-linked hypophosphatemic vitamin D resistant rickets (XLH), combined therapy of phosphate and calcitriol is the best therapeutic approach at present. However, the complications involving combined therapy, such as hypercalcemia, nephrocalcinosis and hyperparathyroidism, are not fully solved. To achieve better control, new therapeutic approaches have been reported recently, for example, growth hormone (GH) or new vitamin D analogs. GH improved linear growth, decreased phosphate reabsorption and increased 1-α-hydroxylase activity. Furthermore, 24R, 25-dihydroxyvitamin D₃ (24,25) improved the bone lesions in hypophosphatemic (Hyp) mice, and also in XLH, without the adverse effects such as hypercalcemia or hypercalciuria compared with 1,25-dihydroxyvitamin D₃. These new approaches should be considered for the treatment of patients with XLH.