Expression and localization of P1 promoter-driven hepatocyte nuclear factor-4α (HNF4α) isoforms in human and rats.

BACKGROUND: Hepatocyte nuclear factor-4α (HNF4α; NR2A1) is an orphan member of the nuclear receptor superfamily involved in various processes that could influence endoderm development, glucose and lipid metabolism. A loss-of-function mutation in human HNF4α causes one form of diabetes mellitus called maturity-onset diabetes of the young type 1 (MODY1) which is characterized in part by a diminished insulin secretory response to glucose. The expression of HNF4α in a variety of tissues has been examined predominantly at the mRNA level, and there is little information regarding the cellular localization of the endogenous HNF4α protein, due, in part, to the limited availability of human HNF4α-specific antibodies. RESULTS: Monoclonal antibodies have been produced using baculovirus particles displaying gp64-HNF4α fusion proteins as the immunizing agent. The mouse anti-human HNF4α monoclonal antibody (K9218) generated against human HNF4α1/α2/α3 amino acids 3-49 was shown to recognize not only the transfected and expressed P1 promoter-driven HNF4α proteins, but also endogenous proteins. Western blot analysis with whole cell extracts from Hep G2, Huh7 and Caco-2 showed the expression of HNF4α protein, but HEK293 showed no expression of HNF4α protein. Nuclear-specific localization of the HNF4α protein was observed in the hepatocytes of liver cells, proximal tubular epithelial cells of kidney, and mucosal epithelial cells of small intestine and colon, but no HNF4α protein was detected in the stomach, pancreas, glomerulus, and distal and collecting tubular epithelial cells of kidney. The same tissue distribution of HNF4α protein was observed in humans and rats. Electron microscopic immunohistochemistry showed a chromatin-like localization of HNF4α in the liver and kidney. As in the immunohistochemical investigation using K9218, HNF4α mRNA was found to be localized primarily to liver, kidney, small intestine and colon by RT-PCR and GeneChip analysis. CONCLUSION: These results suggest that this method has the potential to produce valuable antibodies without the need for a protein purification step. Immunohistochemical studies indicate the tissue and subcellular specific localization of HNF4α and demonstrate the utility of K9218 for the detection of P1 promoter-driven HNF4α isoforms in humans and in several other mammalian species.

Impaired tubular excretory function as a late renal side effect of chemotherapy in children.

PURPOSE: Renal drug excretion is variously influenced by nephrotoxic drugs. This study was designed to evaluate renal function as a late renal side effects in children receiving combination chemotherapy for malignancy. PATIENTS AND METHODS: Follow-up studies of 30 newly diagnosed patients were performed a median of 12 months after completion of chemotherapy. The glomerular filtration rate (GFR) was measured using sodium thiosulfate. The following were also assessed: urinary high-molecular-weight fraction (urinary albumin/urinary creatinine ratio); para-aminohippurate (PAH) clearance; urinary low-molecular-weight fraction (urinary beta2-microglobulin/urinary creatinine ratio); and routine serum and urinary parameters. RESULTS: Serum and urinary electrolytes were normal in most patients. GFR was low in four patients (13%). Urinary high-molecular-weight fraction was elevated in two patients. Urinary low-molecular-weight fraction was elevated in one patient. PAH clearance was below the referenced normal value in 73% of the patients. CONCLUSIONS: This report demonstrates decreased PAH clearance as a late renal side effect of chemotherapy and suggests disturbed function of the organic anion transport system. The unexpected high serum concentration of drugs excreted through the organic anion transport system may induce severe side effects. Elucidation of the mechanism and clinical relevance of decreased PAH clearance is warranted.

Centrofacial malignant T-cell lymphoma exhibiting recurrent fever and skin ulcer in a 3-year-old girl.

A rare case of undetermined fever and skin ulcers is reported. The patient had an 8-month history of recurrent fever, destructive ulceration of the midline facial tissue, and symmetrical skin ulcer in the cheeks and the back of the hand. Pathological examination revealed that the patient had lethal midline granuloma (centrofacial malignant T-cell lymphoma), which is very rare in childhood. Centrofacial malignant T-cell lymphoma should be considered as a differential diagnosis of unexplained fever and skin ulcer in children.

Acute suppurative thyroiditis as a rare complication of aggressive chemotherapy in children with acute myelogeneous leukemia.

Acute suppurative thyroiditis (AST) is quite rare, even in immunocompromised patients. The authors describe 2 cases of AST during aggressive chemotherapy for acute myelogeneous leukemia (AML). They were treated with aggressive combination chemotherapy and achieved complete remission. After several courses of chemotherapy, they developed fever and pain in the region of the thyroid gland. Laboratory tests showed hyperthyroidism and elevated levels of thyroglobulin and C-reactive protein. Ultrasonography revealed hypoechoic areas in the thyroid gland. A diagnosis of AST was made. Bacterial infections were suspected because they were sucessfully treated with antibiotics. After a month, the patients' thyroid function and thyroglobulin levels returned to normal without a period of transient hypothyroidism. A pyriform sinus fistula was not demonstrated. The results suggest that neutropenia and preceding cellulitis around the thyroid gland, which might be subsequent to oral mucosal damage induced by anticancer drugs, may play a role in the development of AST. AST should be considered a potential complication of aggressive chemotheragy for leukemia.