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A Yam

Publications and source records attributed to A Yam.

30 records · Page 2Linked to original sources
PubMed1985

Factor VIII-related antigen levels in normal pregnancy and puerperium.

The changes in serum Factor VIII-related antigen (Factor VIII RAg) levels in normal pregnancy and puerperium in Chinese women were studied by the Laurell 'rocket' immunoelectrophoresis. At 6 wk of gestation, the serum Factor VIII RAg levels were already higher than those of non-pregnant women and gradually increased through term pregnancy. Parturition did not have immediate effects on the circulating levels of Factor VIII RAg. The levels of Factor VIII RAg observed during labour and days 1-5 postpartum were similar to those of term pregnancy. By the 6th wk postpartum, the serum Factor VIII RAg declined to basal levels, similar to those of non-pregnant control samples.

Antigens↗
PubMed1983

Immunocytochemical localization of alpha-D-mannosidase II in the Golgi apparatus of rat liver.

Mannosidase II is involved in the trimming of alpha-1,6-mannosyl residues during the biosynthesis of glycoproteins containing N-linked oligosaccharides of the complex type. A highly specific polyclonal antibody (IgG) was isolated from rabbits immunized with a homogeneous preparation of mannosidase II prepared from rat liver. With this antibody, light and electron microscopic immunocytochemical studies on rat liver reveal that essentially all mannosidase II in hepatocytes is localized in the Golgi apparatus, the only other site with reaction product being the endoplasmic reticulum. The indirect immunocytochemical method used in this study involved three major steps: exposure of aldehyde-fixed tissue to immune and nonimmune IgG, treatment with staphylococcal protein A labeled with horseradish peroxidase, and incubation in diaminobenzidine to reveal sites of peroxidase activity. The procedures described overcome major problems in immunocytochemistry, allowing preservation of antigenic sites and maintaining adequate ultrastructural integrity. The in situ localization of other carbohydrate-processing enzymes, involved in either trimming or attachment of sugar residues, should be possible with this procedure. Because biosynthetic precursors of the processing enzymes may be revealed by an immunocytochemical approach, it is potentially significant that mannosidase II reaction product is present in areas of the endoplasmic reticulum as well as in the Golgi apparatus.

Animals↗
PubMed1983

Immunocytochemical localization of lysosomal beta-galactosidase in rat liver.

beta-galactosidase is a ubiquitous lysosomal hydrolase that specifically cleaves terminal beta-galactosyl residues from glycoproteins, glycosaminoglycans, oligosaccharides, and glycolipids. To study the intracellular distribution of this enzyme, we prepared a specific polyclonal antibody to lysosomal beta-galactosidase by immunizing rabbits with a highly purified preparation of beta-galactosidase from rat liver. Using this antibody we employed an immunocytochemical technique (protein A coupled to horseradish peroxidase and diaminobenzidine cytochemistry) and showed that beta-galactosidase is present in all hepatocytes of the rat liver. All types of lysosomes, the rough endoplasmic reticulum, and the specialized region of smooth endoplasmic reticulum known as GERL showed immunoreactivity. This in situ distribution suggests that these organelles are involved in the biosynthesis and intracellular sorting of this lysosomal enzyme.

Animals↗
PubMed1981

Lysosomal compartment of macrophages: extending the definition of GERL.

"Professional phagocytes" such as Kupffer cells show an extensive network of interconnected residual bodies with cytochemically demonstrable acid phosphatase [orthophosphoric monoester phosphohydrolase (acid optimum), EC 3.1.3.2]. In such cells and in other (hepatocytes, etc.) this compartment may be considered a part of GERL [a hydrolase-rich region of endoplasmic reticulum (ER) situated at the trans face of the Golgi apparatus from which various Lysosomes appear to arise].

Acid Phosphatase↗
PubMed1979

Immunocytochemical localization of epoxide hydrase in hyperplastic nodules induced in rat liver by 2-acetylaminofluorene.

A knowledge of the biological characteristics of carcinogen-induced hyperplastic nodules of rat liver may be important in the understanding of cancer development. Although its biological role remains to be elucidated, the level of microsomal epoxide hydrase (epoxide hydrolase, EC 3.3.2.3) is 5- to 7-fold greater in hyperplastic nodules nodules induced by feeding the hepatocarcinogen 2-acetylaminofluorene than in liver of control rats. After removal of the carcinogen from the diet, the high level of the enzyme is maintained in those nodules that persist and in the hepatocellular carcinomas that subsequently develop. The availability of antibody to the epoxide hydrase made it possible to use electron microscopic immunocytochemistry to localize this enzyme in the cells of hyperplastic nodules. The immunocytochemical procedure provides direct visual evidence for the presence of this enzyme in smooth endoplasmic reticulum and also in rough endoplasmic reticulum (including the nuclear envelope) of the nodule's parenchymal cells.

2-Acetylaminofluorene↗
PubMed1979

Biochemical and morphologic studies on diabetic rats: effects of sucrose-enriched diet in rats with pancreatic islet transplants.

Isolated pancreatic islets were administered to Lewis rats with streptozotocin-induced diabetes. Then the rats were fed either a semisynthetic diet containing 60% (wt/wt) sucrose for 3 weeks or were continued on chow. Transplantation resulted in a decrease in serum glucose, an increase in serum insulin, and a marked decrease in serum triacylglycerol, particularly in the sucrose-fed diabetic rats. In these rats, in demarcated areas of hepatocytes surrounding portal vein termini, lipid was deposited in the cytosol and large lipoprotein particles engorged the Golgi apparatus, Golgi-derived secretory vacuoles, and GERL. This model permits observation of the effects of pancreatic islet hormones on lipogenesis by hepatocytes in situ.

Animals↗
PubMed1978

Sites of lipoprotein particles in normal rat hepatocytes.

Very low density lipoprotein (VLDL) particles are packaged by the Golgi apparatus into vacuoles which move to the plasma membrane and empty the particles into the space of Disse, via exocytosis. Traditionally, all lipoprotein-containing cisternae and vacuoles are thought to be parts of this pathway. Observations reported here demonstrate that there is a second population of lipoprotein-containing cisternae and vacuoles. This population is part of GERL, an organelle we consider to be a specialized hydrolase-rich region of the endoplasmic reticulum (ER). To our knowledge, this is the first systematic study of GERL in normal rat hepatocytes.

Acid Phosphatase↗
PubMed1978

The cytochemical demonstration of GERL in rat hepatocytes during lipoprotein mobilization.

When a semisynthetic diet containing 1% orotic acid (OA) is fed to rats, the endoplasmic reticulum (ER) of hepatocytes vesiculates and lipoprotein (LP) droplets accumulate within the vesicles. When clofibrate (ethyl chlorophenoxyisobutyrate, CPIB) is added to the orotic acid-rich diet, the ER cisternae reform and the LP is mobilized through the reconstituted ER. A remarkable restoration of normal hepatocyte ultrastructure occurs except for a few organelles. From their morphological appearance it was suggested that cisternae which became dilated with small LP particles were part of GERL, abnormally enlarged. The present communication validates this interpretation through ultrastructural cytochemistry which can distinguish GERL from the adjacent Colgi apparatus. GERL shows acid phosphatase (AcPase) but not thiamine pyrophosphatase (TPPase) activity. In contrast, the adjacent Golgi element shows thiamine pyrophosphatase but not acid phosphatase activity. From such cytochemical studies we have recently proposed that GERL in normal rat hepatocytes may be involved in transforming LP particles, by enzymes like lipases that were presumed to be present in this hydrolase-rich portion of smooth ER. In the situation studied in this communication, the addition of ethyl chlorophenoxyisobutyrate to the diet causes the release from the ER of large amounts of LP to the Golgi apparatus and to GERL. Apparently the capacity of GERL to metabolize LP is exceeded and lipid accumulates in the residual bodies.

Acid Phosphatase↗
PubMed1977

Studies of the secretory process in the mammalian exocrine pancreas. I. The condensing vacuoles.

Phosphatase cytochemistry was used to distinguish between the Golgi apparatus and GERL (considered as a specialized region of endoplasmic reticulum [ER] at the inner [trans] aspect of the Golgi stack) in pancreatic exocrine cells of guinea pig, rat, rabbit, and hamster. The trans element of the Golgi stack exhibits thiamine pyrophosphatase (TPPase) but no acid phosphatase (AcPase) activity. In contrast, GERL shows AcPase but no TPPase activity. The nascent secretory granules, or condensing vacuoles, are expanded cisternal portions of GERL. Continuities of condensing vacuoles with rough ER are suggested, and it is proposed that some secretory components may have direct access to the condensing vacuoles from ER. Connections of Golgi apparatus with GERL were not seen.

Acid Phosphatase↗
PubMed1975

Cytochemical study of secretory process in transplantable insulinoma of syrian golden hamster.

Electron microscopy, including phosphatase cytochemistry, indicates that the secretory granules of an insulinoma producing proinsulin and insulin are packaged by the endoplasmic reticulum (ER) and especially by a specialized region of ER which we call GERL because of the spatial relationship of this region to the Golgi apparatus and its apparent role in producing lysosomes. The granules are not derived from the Golgi apparatus. Preliminary evidence suggests this may be true also of pancreatic beta-cells.

Acid Phosphatase↗