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  • 1
    ISSN: 1432-0878
    Keywords: Key words: Aging ; Dietary restriction ; Hepatocytes ; Cell proliferation ; Proliferating cell nuclear antigen ; Cell death ; Terminal dUTP nick end labeling (TUNEL) ; Rat (Fischer 344)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The proliferation and death of hepatocytes in rats fed ad libitum and rats on dietary restriction were evaluated in 3 to 24-month-old rats by employing immunocytochemistry for proliferating cell nuclear antigen (PCNA) and terminal dUTP nick end labeling (TUNEL). These techniques were also used to examine hepatic tissue infiltrated with leukemic cells in 24-month-old rats fed ad libitum. PCNA-strongly positive hepatocytes, PCNA-positive hepatocytes, and TUNEL-positive hepatocytes were reported previously to be equivalent to hepatocytes in the S phase, hepatocytes in the cell cycle, and dying hepatocytes, respectively. The proportion of PCNA-strongly positive hepatocytes and PCNA-positive hepatocytes declined with age. Dietary restriction diminished PCNA-strongly positive hepatocytes significantly but not PCNA-positive hepatocytes in young rats, but the proportion of PCNA-strongly positive hepatocytes was significantly higher following dietary restriction than that in rats fed ad libitum in advanced age. Growth stimulation by leukemic cell infiltration resulted in a recovery of the age-related decline of PCNA-strongly positive hepatocytes. Aging was associated with a progressive increase in the proportion of TUNEL-positive hepatocytes, with a smaller effect following dietary restriction than in rats fed ad libitum after 6 months of age. Our results indicate that age and dietary restriction induce proliferative inhibition. The inhibition depends on PCNA expression; this suggests that suppression of cell proliferation and cell death are enhanced in hepatocytes of senile rats.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1574-4647
    Keywords: Aging ; dietary restriction ; somatotrope ; cell renewal ; growth hormone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We investigated the impact of dietary restriction on the basal rate of somatotrope renewal in the pituitary gland. Bromodeoxyuridine (BrdU), a thymidine analog, was administered continuously for 1 week in male F344 rats at 3, 8 and 20 months of age (mo), fed ad libitum (AL) or diet restricted from 1.5 mo (DR). Combined immunostainings for BrdU and GH visualized newly formed somatotropes as well as pituitary cells in tissue sections. The rate of incorporation of BrdU by anterior pituitary cells (BrdU-labeled nuclei/100 nuclei) was not influenced by the dietary regimen or age. The fraction of BrdU-labeled somatotropes relative to all labeled cells precipitously decreased to the same level in both dietary groups between 3 and 8 mo, although the fraction was greater in DR rats at 3 mo. In AL rats, the fraction decreased further between 8 and 20 mo, while it stabilized in DR rats. Our results suggested that dietary restriction maintains the basal rate of somatotrope renewal in later life in male rats. Although one must also estimate the effects of dietary restriction on apoptotic cell death in pituitary cells, the present study provides evidence that dietary restriction modulates somatotropes cell turnover and preserves the cell population for GH secretion during aging.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular neurobiology 17 (1997), S. 141-150 
    ISSN: 1573-6830
    Keywords: vascular endothelial growth factor ; basic fibroblast growth factor ; ethylnitrosourea-induced rat glioma ; digoxigenin ; in situ hybridization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract 1. Which angiogenic growth factors actually mediate tumor growth in ethylnitrosourea (ENU)-induced gliomas in rats was examined. 2. In situ hybridization histochemistry with digoxigenin-labeled oligonucleotide probes was used to investigate the cellular expression and distribution of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) mRNAs in ENU-induced gliomas. 3. Both VEGF and bFGF mRNAs were not detected in normal gial cells but in ENU-induced glioma cells. 4. Our results suggest that the growth of ENU-induced glioma may be regulated by multiple angiogenic growth factors and that these gliomas may proliferate by synthesizing such growth factors.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1435-5922
    Keywords: Key words: acinar cell carcinoma ; carcinoma of the pancreas ; hypoglycemia ; insulin-like growth factor II
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract: Apart from insulinomas, pancreatic tumors are rarely complicated by hypoglycemia and some may produce insulin-like growth factor II (IGF-II). To our knowledge, IGF-II-producing pancreatic tumors associated with hypoglycemia have not been reported previously. We describe what we believe to be the first case of "big" IGF-II-producing pancreatic acinar cell carcinoma. A 68-year-old man presented with a history of recurrent hypoglycemia. Abdominal computed tomography scan and magnetic resonance imaging showed a mass, approximately 5 cm in diameter, in the tail of the pancreas and two low-density areas in the liver. Low serum glucose was associated with low insulin levels and high levels of hormones (i.e., glucagon and IGF-II) that are functionally opposite to insulin. Although serum IGF-II level was within the normal range, most IGF-II was of the high molecular weight form, as determined by Western immunoblot analysis. Based on these findings, a diagnosis of hypoglycemia induced by IGF-II-producing pancreatic tumor was made. Surgery was not possible because of the patient's poor general condition. The patient ultimately died as a result of malignant cachexia. At autopsy, a yellowish-white tumor was found in the tail of the pancreas, and a histopathologic diagnosis of acinar cell carcinoma was made. Immunohistologically, the tumor cells contained IGF-II in an irregular staining pattern, suggesting that the hypoglycemia was caused by a pancreatic tumor producing "big" IGF-II.
    Type of Medium: Electronic Resource
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