Hepatic Proteins in Regenerating Liver

Abstract  Albumin immunoreactivity in the liver was examined on days 2, 5 and 10 after two-thirds partial hepatectomy by light and ultrastructural immunoperoxidase methods and the ultrastructural area of the rough endoplasmic reticulum (ER) in hepatocytes was measured. Albumin immunoreactivity was seen in the rough ER and Golgi apparatus of all hepatocytes in the hepatectomized liver and ultrastructural analysis showed a significantly greater area of rough ER on day 5 than on days 2 or 10. Albumin mRNA was studied by the in situ hybridization technique using radioisotopes and their numbers were determined visually. Albumin mRNA was present as grains in all hepatocytes and the grains varied in number during regeneration of the liver, being more abundant on day 5 than on days 2 or 10. The activity of [³H]-leucine incorporated into albumin synthesis, an indicator of translational activity, was higher on days 5 and 10 than on day 2 and was highest on day 5. In conclusion, albumin synthesis varied during liver regeneration after partial hepatectomy, being reduced at the peak of cell proliferation on day 2 and being most active on day 5.     

Effects of colchicine on the synthesis and transport of albumin: A combined electron cytochemical and autoradiographic study

We investigated the intracellular transport of albumin in the livers of rats treated with colchicine using immunoperoxidase study as well as combined immunoelectron microscopy and autoradiography with [³H]-leucine. Immunoreaction of albumin was observed in all hepatocytes. Its subcellular location was in the rough endoplasmic reticulum, Golgi apparatus and lysosomes. After the injection of [³H]-leucine through the portal vein, a combined technique revealed accumulated grains on the albumin-positive Golgi apparatus or the albumin-positive vesicles in the vicinity of the Golgi apparatus. These findings suggest that albumin transport from the Golgi apparatus to sinusoids is disturbed by colchicine. Enzyme histochemistry showed many acid phosphatase-positive lysosomes in hepatocytes of the liver treated with colchicine. Albumin retained in the vicinity of the Golgi apparatus may be digested by lysosomes. An in situ hybridization study with isotopes revealed the presence of silver grains for albumin mRNA in all hepatocytes of livers treated or untreated with colchicine; there was no significant difference in the number of silver grains in the two groups. Therefore, colchicine has very little effect on albumin synthesis in the liver.     

Iatrogenic superior mesenteric arteriovenous fistula: Ultrasonographic, CT and angiographic features and histological findings of the liver biopsy

Iatrogenic superior mesenteric arteriovenous fistula is rare. We treated a patient with this problem 6 years after small bowel resection for intestinal obstruction. The symptoms and signs were those of intestinal ischaemia and portal hypertension with an abdominal bruit. Ultrasonography and enhanced computerized tomography of the abdomen suggested the presence of superior mesenteric arteriovenous fistula, with a dilated portal vein and a communication between the dilated superior mesenteric vein and its artery. The exact location of the fistula was then determined by selective superior mesenteric arteriography. The fistula was ligated in an emergency operation to prevent cardiac or renal failure and to relieve portal hypertension. Liver biopsy showed no cirrhotic changes, but fibrosis was seen around the portal veins. We describe here not only the diagnostic arteriographic findings of superior mesenteric arteriovenous fistula, but also the interesting and suggestive ultrasonographic and computed tomographic findings. Early correction of such fistulas is recommended to prevent cardiac or liver failure.     

TRICHOHYALIN EXPRESSION IN SKIN TUMORS: RETRIEVAL OF TRICHOHYALIN ANTIGENICITY IN TISSUES BY MICROWAVE IRRADIATION

Background. The antitrichohyalin antibody AE 15 is effective for identifying the cell lineage that undergoes the pathway of inner root sheath-type differentiation. Unfortunately, the AE 15 does not react with trichohyalin in tissue that is formalin-fixed and embedded in paraffin according to routine procedures. Methods. We attempted to retrieve the trichohyalin antigenicity in formalin-fixed, paraffin-embedded biopsy specimens that included normal skin as well as skin tumors such as trichofolliculoma and pilotricoma. Results. We found that the use of a metal solution in combination with microwave oven heating improves the trichohyalin immunoreactivity substantially. Further, trichohyalin was found to be expressed not only in the secondary hair structure in trichofolliculoma but also in a certain cell lineage that differentiates to squamoid cells in pilomatricoma. Conclusions. Our findings established that surgical specimens processed under routine procedures can be successfully investigated with AE 15 using the microwave irradiation method. Studies of epidermal diseases expressing trichohyalin should provide valuable insights into our understanding the functional significance of trichohyalin during abnormal keratinization.     

Solid-phase synthesis of human osteocalcin by using a γ-carboxyglutamic acid derivative

Human osteocalcin, also called bone Gla protein (BGP), consisting of 49 amino acids with two to three γ-carboxyglutamate residues, was chemically synthesized for the first time by a novel solid-phase peptide synthesis. An l -enantiomer of N-tert-butyloxycarbonyl-γ,γ′-dicyclohexyl-γ-carboxyglutaniic acid was designed, prepared and utilized as a monomeric compound and proven to be useful for the solid-phase peptide synthesis of human osteocalcin. The synthesis and optical resolution of the γ-carboxyglutamic acid (Gla) derivative are first described, followed by the synthesis and characterization of Gla¹⁷-human osteocalcin.     

EXPRESSION OF KERATOHYALIN-TRICHOHYALIN HYBRID GRANULES IN MOLLUSCUM CONTAGIOSUM

Background. Recently, in the filiform papillae epithelium of mouse dorsal tongue, we showed the presence of hybrid granules in which filaggrin and trichohyalin were both present, but physically segregated. Further, trichohyalin was also detected in scattered granular cells of a number of hyperplastic skin diseases. Methods. The epidermis infected with molluscum contagiosum virus (MCV) was studied by conventional electron microscopy in conjunction with light and electron-microscopic immunohistochemistry, using both antifilaggrin and antitrichohyalin antibodies as probes. Results. We found that the granular cells of MCV-infected epidermis contained both filaggrin and trichohyalin. Subsequent electron-microscopic examination showed that the granular cells contained morphologically heterogeneous granules that appeared to be composed of discrete areas of distinct electron densities. Double-labeling, using antibodies to filaggrin and trichohyalin, clearly indicated that filaggrin and trichohyalin were both present in the hybrid granules and that the electron-dense regions contained trichohyalin while the more electron-lucent regions contained filaggrin. Conclusions. The expression of trichohyalin was a common feature observed in the epidermis from a heterogenous group of hyperplastic conditions, including MCV Infection. This finding has led us to speculate that trichohyalin may be specifically or preferentially involved in interacting with the hyperproliferation-related keratin pair (K6/K16), whereas the function of filaggrin is more closely linked to the skin-type keratin pair (K1/K10) that are normal keratins found in the differentiated epidermis.