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  • 1
    Electronic Resource
    Electronic Resource
    Immunogold-silver staining and epipolarized light microscopic detection of phosphoenolpyruvate carboxykinase and glycogen phosphorylase in rat liver (1993)
    Springer
    Histochemistry and cell biology 99 (1993), S. 341-346 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The subcellular distribution of enzymes related to carbohydrate metabolism was determined in sections of paraformaldehyde fixed and polyethylene glycol-1540-embedded rat liver and in cryostat sections. For this purpose, goat anti-rat phosphoenolpyruvate carboxykinase (PEPCK) serum and rabbit anti-rat glycogen phosphorylase (GP) serum were used as primary antibodies to localize the corresponding antigens. The primary antibodies were localized by 5 nm colloidal gold labeled secondary antibodies (either rabbit anti-goat IgG for PEPCK or goat anti-rabbit IgG for GP), and the gold particles were enhanced by silver staining using appropriate development reagents. The silver enhanced gold particles were detected by epipolarized light microscopy. PEPCK and GP immunoreactive molecules were found only in glycogen-containing areas of the cytosome of hepatocytes, and not in other cells. No immunocytochemical staining of hepatocytes was found when normal serum replaced the primary antibody in the procedures. Visio-Bond semithin (0.35–1.0 μm) sections provided higher resolution for subcellular immunostaining of PEPCK and GP than cryosections of 10 μm. Epipolarized light microscopy provided detection at high sensitivity of the gold-labeled antibody, and combined with transmitted light, allowed simultaneous visualization of the tissue morphology.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00717045
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  • 2
    Electronic Resource
    Electronic Resource
    Maternal malnutrition does not affect fetal hepatic glycogen synthase ontogeny (1993)
    Springer
    Digestive diseases and sciences 38 (1993), S. 1500-1504 
    Details
    ISSN: 1573-2568
    Keywords: maternal malnutrition ; fetal mice ; hepatic glycogen synthase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Maternal malnutrition late in pregnancy results in the reduced storage of fetal hepatic glycogen in the final days of gestation and an accentuation of normal birth-related hypoglycemia. It was of interest to determine whether or not low glycogen levels resulted when maternal malnutrition disrupted the normal ontogeny of fetal hepatic glycogen synthase, an important glycogenic enzyme. A defect in this enzyme would be expected to seriously affect prenatal and postnatal glycogen synthesis. For this study, livers were removed from fetuses from malnourished (50% of normal dietary intake) mice, as well as fromad libitum-fed mice, and used for the determination of hepatic glycogen, glycogen synthase activity, and glycogen synthase protein levels. In this paper we report that maternal dietary restriction late in pregnancy produces growth-retarded fetuses with severely reduced hepatic glycogen levels, but the normal ontogenic changes in the quantity and activity of hepatic glycogen synthase were not affected. It is especially significant that the accumulation of glycogen synthase occurred despite the minimal level of natural substrate available for the enzyme. These results suggest that the accumulation and activity of hepatic glycogen synthase during late gestation is related to developmental events rather than levels of substrate or glycogen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01308611
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  • 3
    Electronic Resource
    Electronic Resource
    Morphological and biochemical observations on hepatic glycogen metabolism in mice on a controlled feeding schedule (1982)
    Springer
    Digestive diseases and sciences 27 (1982), S. 680-691 
    Details
    ISSN: 1573-2568
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Changes in hepatocyte morphology were correlated with chemically measured liver glycogen, blood glucose, and plasma insulin levels in control-fed mice (6 hr fed, 18 hr fasted) sacrificed at various time intervals after initiation of a 6-hr meal. At initiation of feeding hepatic glycogen was low (0.05%) but deposition proceeded rapidly, reaching a maximum of 6.99±0.13% by the sixth hour. Glycogen was depleted during the subsequent fasting period, reaching the prefeeding levels by 24 hr. A relative hyperglycemia (140–192 mg/100 ml) predominated during all stages of glycogen deposition and depletion until the 21 st hour. Plasma insulin levels were maximum during feeding (63±7 μU/ml, 3 hr) with mild hyperinsulinemia (insulin〉16 μU/ml) occurring during glycogen depletion (9–21 hr). Histochemical determinations (PAS) showed lobular patterns of hepatic glycogen which correlated with chemically measured glycogen levels. Six hours after initiation of feeding, periportal cells showed intensely stained masses of glycogen while centrilobular cells showed relatively diffuse staining. At 24 hours after initiation of feeding (18 hr of fasting), no significant staining was observed in the hepatocytes. Ultrastructurally, during all stages of glycogen deposition and depletion, centrilobular cells were characterized by the presence of dispersed glycogen particles with elements of smooth endoplasmic reticulum (SER) between the particles, while periportal cells showed dense glycogen deposits with SER restricted to the periphery of the glycogen masses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01393762
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  • 4
    Electronic Resource
    Electronic Resource
    Morphological and biochemical observations on hepatic glycogen metabolism in mice on a controlled feeding schedule (1982)
    Springer
    Digestive diseases and sciences 27 (1982), S. 692-700 
    Details
    ISSN: 1573-2568
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Morphological aspects of hepatic glycogen metabolism in streptozotocin (SZ) diabetic mice on a controlled feeding cycle (6 hr fed, 18 hr fasted) were studied and correlated with plasma glucose and insulin levels at various time intervals after feeding. Hepatic glycogen was low at initiation of feeding (∼0.05%) and increased to a maximum of 4.54±0.30% (N=8) as compared to 6.90±0.20% (N=12) in normal animals. Plasma glucose levels were similar to those of normal mice at initiation of feeding (80±5 mg/dl) but much higher during the feeding period (diabetic: 540±15 mg/dl, normal: 150±10 mg/dl). At the end of the feeding period, plasma glucose levels rapidly declined, reaching lower than normal levels. In contrast to insulin responses to feeding in normal animals, plasma insulin levels in SZ-diabetic mice remained very low, never exceeding 16 μU/ml. At maximum hepatic glycogen deposition, light microscopic studies showed atypical patterns of glycogen distribution with periportal cells having generally smaller-than-normal glycogen masses. Ultrastructural studies indicated that these cells contained more abundant quantities of smooth endoplasmic reticulum (SER) than is characteristically seen. The aberrant distribution patterns of glycogen observed in the diabetic mice provided morphological evidence for the proposal that the SER is involved in hepatic glycogenesis, with insulin deficiency resulting in abnormal functioning of the organelle.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01393763
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  • 5
    Electronic Resource
    Electronic Resource
    Correlation between structure and glycogen content of livers from rats on a controlled feeding schedule (1973)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 177 (1973), S. 23-37 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Male rats were maintained on a controlled feeding schedule and groups of animals sacrificed at 2, 15, 21, 36, 48 and 72 hours of fasting. Chemical determinations of glycogen showed that livers of rats fasted two hours contained 8.7% glycogen; 15 hours, 6.2%; 21 hours, 0.7%; 36 hours, 0.7%; 48 hours, 0.8%; and 72 hours, 0.4%. After PA/S procedures, glycogen appeared in hepatocytes of rats fasted 2 and 15 hours as large masses intensely stained. At these time-periods, almost all cells contained significant quantities of glycogen but hepatocytes located toward portal tracts showed larger and more intensely stained masses of glycogen than found in cells near central veins. After longer periods of fasting, glycogen masses decreased in size, number, and staining intensity. The fine structure of hepatocytes from rats fasted 2 or 15 hours showed abundant α and β particles of glycogen in the form of large masses throughout the cytosome. These correlated in position and shape to the masses of glycogen seen in the light microscope. As glycogen depletion occurred (fasted 21 hours and longer) the number of glycogen particles decreased in hepatocytes. It is concluded from this study that a good correlation exists between chemical determinations of hepatic glycogen, cytochemistry of glycogen in hepatocytes, fine structure of liver cells, and the fasting state of the animal.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091770104
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  • 6
    Electronic Resource
    Electronic Resource
    Alterations in the endoplasmic reticulum and golgi complex of intestinal epithelial cells during fat absorption and after termination of this process: A morphological and morphometric studyThe opinions or assertions contained herein are the private views of the authors and are not to be construed as official or as reflecting the views of the Department of the Army or the Department of Defense. (1977)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 188 (1977), S. 77-101 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Earlier investigations of intestinal fat-absorption have stressed the importance of continued protein synthesis to provide membranes which are utilized for the intracellular transport of resynthesized lipid. The resulting membranes, when incorporated into the endoplasmic reticulum (ER) and Golgi complex, serve as vehicles for the movement of fat within the cell and for its release to the extracellular space. In the current study, attention was focused on the morphological changes in the ER and Golgi complex both during fat absorption and at successive time intervals after fat-absorption termination. Morphological interpretations were confirmed by morphometric analysis. This investigation supports the interpretation that during fat absorption, membrane synthesis by the rough endoplasmic reticulum (RER) is insufficient to accomodate membrane utilization and intraconversion, resulting in a decrease of both ER and Golgi complex components. However, following fat-absorption termination, the cell is able to replace previously depleted components of the ER and Golgi complex and regain the full membrane complement of the fasted state. Replenishment of cellular membranes is postulated as resulting from a continued synthesis of new membranes by the RER which eventually exceeds membrane utilized during lipid transport.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091880109
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  • 7
    Electronic Resource
    Electronic Resource
    Action of metabolic hormones on the fine structure of rat liver cells III. Effects of adrenalectomy and administration of cortisone (1974)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 180 (1974), S. 309-329 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Electron microscopic studies were made of hepatocytes from sham-operated rats, adrenalectomized animals fasted 15 hours, and adrenalectomized rats fasted 15 hours but given a single I.P. injection (10 mg) of cortisone acetate. The objective of this work was to define the earliest morphological response of hepatocytes to injection of a glucocorticoid and to provide additional information on the mechanism of hormone action at the cellular level. Hepatocytes from fasted, adrenalectomized rats contained no glycogen particles and very little smooth endoplasmic reticulum (SER). In addition the rough endoplasmic reticulum was disorganized and showed fewer ribosomes and polysomes than found in liver cells from sham-operated rats. Two hours after glucocorticoid injection glycogen particles were seen in numerous centrilobular cells and some periportal hepatocytes. Elements of SER were associated with the glycogen particles. By 4 hours after hormone injection abundant glycogen was found in all hepatocytes. Centrilobular cells showed dispersed glycogen with extensive tubules of SER associated with the glycogen particles. Periportal hepatocytes accumulated glycogen as dense masses scattered throughout the cytosome. SER occurred mainly at the edges of the glycogen masses. Midlobular cells showed glycogen patterns intermediate between periportal and centrilobular cells; masses of dispersed glycogen with abundant SER occurred within and around the glycogen areas of the cells. Glucocorticoid stimulation also caused cisternae of RER to align in parallel arrays, and more ribosomes and polysomes appeared on membranes of RER than in similar cells from adrenalectomized rats. The interpretation is offered that the glucocorticoid-stimulated proliferation of SER is the morphological expression of induced microsomal enzyme synthesis (glucose-6-phosphatase) known to occur under these hormonal conditions.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091800206
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  • 8
    Electronic Resource
    Electronic Resource
    Comparison of 3H-galactose and 3H-glucose as precursors of hepatic glycogen in control-fed rats (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 224 (1989), S. 22-28 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Labeling of hepatic glycogen derived from 3H-galactose and 3H-glucose was compared shortly after intravenous injection in control-fed rats. The rats were allowed to accumulate 5-8% glycogen prior to receiving label. Fifteen minutes to 2 hours after labeling, liver was excised and processed for routine light (LM) and electron microscopic (EM) radioautography (RAG) or biochemical analysis. After injection of 3H-galactose, LM-RAGs revealed that the percentage of heavily labeled hepatocytes increased from 37% after 15 minutes to 68% after 1 hour but showed no further increase after 2 hours. α-Amylase treatment removed most glycogen and incorporated label; thus few silver grains were observed, indicating little incorporation of label except into glycogen. EM-RAGs demonstrated that most label occurred where glycogen was located. Biochemical analysis showed initially a high blood level of label that rapidly plateaued at a reduced level by 5 minutes. Concomitantly, glycogen labeling determined by liquid scintillation counting reflected the increases observed in the RAGs. After injection of 3H-glucose, LM-RAGs revealed that only 12% of the hepatocytes were heavily labeled at 1 hour and 20% at 2 hours. In tissue treated with α-amylase, glycogen was depleted and label was close to background level at each interval observed. EM-RAGs showed most grains associated with glycogen deposits. Biochemically, blood levels of label persisted at a high level for 30 minutes and tissue levels increased slowly over the 2-hour period. This study shows that incorporation from 3H-galactose was more rapid than incorporation of 3H-glucose; however, label derived from both carbohydrates appeared to be incorporated mainly into glycogen.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092240105
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  • 9
    Electronic Resource
    Electronic Resource
    Alterations in hepatic fine structure after chronic exposure of rats to dexamethasone (1978)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 192 (1978), S. 73-87 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The objective of this study was to determine the effects of chronic dexamethasone (DEX) administration on hepatic ultrastructure and to correlate these changes with plasma lipoprotein levels. Electron microscopic studies were made of hepatocytes from male rats killed 1, 3 and 5 days after DEX (2 mg, twice per day) administration. Three days after treatment plasma lipoprotein levels were highest and hepatocytes contained regions of the cytosome rich in elements of the smooth endoplasmic reticulum (SER). Osmiophilic particles were present in the tubules and vesicles of the SER, in the saccules and vacuoles of the Golgi complex, in secretory vesicles near the cell surface and in the space of Disse. DEX treatments also caused hepatocytes to accumulate tightly packed masses of β-particles of glycogen in some regions of the cell while other areas displayed dispersed glycogen particles that were associated with the SER. These observations are consistent with the hypothesis that glucocorticoids 1. cause an elevation of plasma lipoprotein levels by in creasing hepatic synthesis and secretion of VLDL, which involves the sequential participation of the ER, the Golgi complex and exocytosis of VLDL-containing vacuoles into the space of Disse, and 2. produce a change in the nature of the association of glycogen particles with the SER membranes in response to the physiological state of the animal.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091920107
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  • 10
    Electronic Resource
    Electronic Resource
    Glycogen metabolism in cultured chick hepatocytes: A morphological study (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 227 (1990), S. 321-333 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Ultrastructural and autoradiographic observations of cultured chick hepatocytes under the following conditins are described: Induction of glycogen synthesis with glucose alone and glucose plus insulin, and glucagon-induced glucogen glucogen breakdown. Profiles of hepatocytes cultured in medium containig 10 mM glucose showed typical cellular organelles and occasionally a few glycogen granules. After incubation of hepatocytes with 3H-glucose, silver grains were found over these sparse glycogen granules, indicating a low level of glycogen synthesis by a few cells. After addition of 75 mM glucose for 1 hr about 3% of the profiles of cells showed glycogen, and by 24 hr half of the hepatocytes had glycogen. Addition ofinsulin plus glucose induced glycogen synthesis in 82% of the cells after 6 hr. and by 24 hr almost every cellular profile showed glyocgen particles. Morphologically, glycogen accumulation was similar whether the cells were stimulated by high glucose or by glucose plus insulin: glycogen granules appeared in restricted regions of the cytoplasm, which were rich in smooth endoplasmic reticulum (SER), and peroxisomes were found close to the newly deposited glycogen particles. At maximum glycogen accumulation the association of SER and peroxisomes with glycogen was less obvious. Glycogenolysis induced by incubation of glycogen-rich hepatocytes with glucagon resulted in proliferation of SER in the glycogen regions of the cells. These observations are compatible with the concept of regions in the hepatocyte cytoplasm specialized for glycogen metabolism. Possible roles for SER and peroxisomes found near glycogen particles and other organelles in hepatic glycogen metabolism are discussed.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092270307
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