The polyamines (putrescine, spermidine, spermine) and the key enzyme controlling their synthesis (ornithine decarboxylase, ODC) are considered important for many adaptive growth responses. In most epithelial cell populations enhanced proliferation is preceded by or associated with elevated ODC activity. We investigated whether inhibition of ODC activity reduces hepatic proliferation after mitogenic challenge. Rats maintained on a 2% oral solution of the L-ornithine analogue α-difluoromethylornithine (DFMO) were compared to positive controls in their response to mitogenic challenge. Adaptive growth was induced by partial hepatectomy (PH), or by a single dose of either phenobarbital (PB) (100 mg kg-1, gastric tube), cyproterone acetate (CPA) (100 mg kg-1, ip) or clofibrate (500 mg kg-1, gastric tube). Although these stimuli normally elevate ODC levels, DFMO proved to be a powerful inhibitor. Inhibition of ODC activity correlated with the absence of detectable levels of putrescine; without DFMO, putrescine levels were approximately 200 nmol g-1 wet weight in each case following mitogenic challenge. Proliferation, as measured by 5-bromo-2′-deoxyuridine (BrdUrd) labeling at 24 h following stimulation, was largely unaffected by DFMO, and hepatic levels of spermidine and spermine were not significantly reduced. The hepatic levels of these downstream polyamines were high despite ODC inhibition, indicating an important role for them in these adaptive growth responses. These data suggest that an alternative polyamine metabolism pathway not affected by DFMO might be in operation here, or that an exogenous source of polyamines might exist.

Conference Article| November 01 1994 POLYAMINE METABOLISM IN HUMAN HEPATOCELLULAR CANCER CELLS (Hep - G2) António A Santos; António A Santos 1Gastroenterology Unit, 18th floor, Guy's Tower, U.M.D.S, Guy's Campus, Guy's Hospital, London SE1 9RT Search for other works by this author on: This Site PubMed Google Scholar Andrew P Stubbs; Andrew P Stubbs 1Gastroenterology Unit, 18th floor, Guy's Tower, U.M.D.S, Guy's Campus, Guy's Hospital, London SE1 9RT Search for other works by this author on: This Site PubMed Google Scholar M Maghsoudloo; M Maghsoudloo 1Gastroenterology Unit, 18th floor, Guy's Tower, U.M.D.S, Guy's Campus, Guy's Hospital, London SE1 9RT Search for other works by this author on: This Site PubMed Google Scholar Gerard M Murphy; Gerard M Murphy 1Gastroenterology Unit, 18th floor, Guy's Tower, U.M.D.S, Guy's Campus, Guy's Hospital, London SE1 9RT Search for other works by this author on: This Site PubMed Google Scholar Mark L Wilkinson Mark L Wilkinson 1Gastroenterology Unit, 18th floor, Guy's Tower, U.M.D.S, Guy's Campus, Guy's Hospital, London SE1 9RT Search for other works by this author on: This Site PubMed Google Scholar Biochem Soc Trans (1994) 22 (4): 384S–385S. https://doi.org/10.1042/bst022385s Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Facebook Twitter LinkedIn MailTo Cite Icon Cite Get Permissions Citation António A Santos, Andrew P Stubbs, M Maghsoudloo, Gerard M Murphy, Mark L Wilkinson; POLYAMINE METABOLISM IN HUMAN HEPATOCELLULAR CANCER CELLS (Hep - G2). Biochem Soc Trans 1 November 1994; 22 (4): 384S–385S. doi: https://doi.org/10.1042/bst022385s Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll JournalsBiochemical Society Transactions Search Advanced Search This content is only available as a PDF. © 1994 Biochemical Society1994 Article PDF first page preview Close Modal You do not currently have access to this content.

Objective: To examine the hypothesis that hepatic bile acid sulphation may be specifically impaired in the cholestatic liver disease, primary biliary cirrhosis (PBC), conceiveably leading to ongoing hepatocyte destruction by retained unconjugated and conjugated hydrophobic bile acids and, conversely, to examine whether sulphation may be induced in PBC to dispose of bile acids retained due to cholestasis.Methods: Under optimum substrate conditions and using butanol extraction, hepatic bile acid sulphotransferase (BAST) activity (pmol bile acid sulphate/mg protein/min) was measured by separately incubating six bile acid substrates with liver cytosol from liver biopsy material obtained from 22 patients with PBC, 17 patients with chronic parenchymal liver diseases, 12 of whom had alcoholic liver disease, and nine normal controls.Results: Sulphotransferase activity was not age-dependent or sex- or tobacco-related. Bile acid sulphotransferase activity was well preserved in patients with PBC, even in those with cirrhosis, but there appeared to be mild reductions in enzyme activity in those with alcoholic liver disease. In PBC patients, there was a positive correlation between BAST activity and serum bilirubin revels when glycochenodeoxycholic acid (r(s)=0.473, P<0.05), lithocholic acid (r(s)=0.504, P<0.05) and taurolithocholic acid (r(s)=0.443, P<0.05) were used as substrates. There was a good correlation for EAST activities for the different substrates in each PBC patient.Conclusions: There was no evidence that primary or secondary reductions in BAST activity contributed to the progression of PBC and it was thought that the reduced enzyme activity in alcoholic liver disease may be due to overall hepatocyte impairment because of the nature of the disease. There is evidence that PBC patients with more severe degrees of cholestasis have increased bile acid sulphation, which could indicate that sulphotransferase enzyme induction occurs in response to cholestasis. Correlation of BAST activities in each patient was indirect evidence that only a single form of the enzyme appears to exist in the human liver.

Conference Article| May 01 1992 Purification of Human Foetal Hepatic Bile Acid Sulphotransferase (BAST) MEHRAN MAGHSOUDLOO; MEHRAN MAGHSOUDLOO 1Gastroenterology Unit, Division of Medicine & Division of Biochemistry, UMDS, Guy's Hospital, London, SE1 9RT, U.K. Search for other works by this author on: This Site PubMed Google Scholar MALCOLM J.P. HIGGINS; MALCOLM J.P. HIGGINS 1Gastroenterology Unit, Division of Medicine & Division of Biochemistry, UMDS, Guy's Hospital, London, SE1 9RT, U.K. Search for other works by this author on: This Site PubMed Google Scholar GERARD M. MURPHY GERARD M. MURPHY 1Gastroenterology Unit, Division of Medicine & Division of Biochemistry, UMDS, Guy's Hospital, London, SE1 9RT, U.K. Search for other works by this author on: This Site PubMed Google Scholar Biochem Soc Trans (1992) 20 (2): 167S. https://doi.org/10.1042/bst020167s Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Share Icon Share Twitter LinkedIn Cite Icon Cite Get Permissions Citation MEHRAN MAGHSOUDLOO, MALCOLM J.P. HIGGINS, GERARD M. MURPHY; Purification of Human Foetal Hepatic Bile Acid Sulphotransferase (BAST). Biochem Soc Trans 1 May 1992; 20 (2): 167S. doi: https://doi.org/10.1042/bst020167s Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search nav search search input Search input auto suggest search filter All ContentAll JournalsBiochemical Society Transactions Search Advanced Search This content is only available as a PDF. © 1992 Biochemical Society1992 Article PDF first page preview Close Modal You do not currently have access to this content.

The effect of inhibition of polyamine biosynthesis by alpha-difluoromethylornithine (DFMO) on the growth of two murine transplantable tumours was studied. Female CBA mice were implanted with either the sarcoma F (SaF) or an anaplastic mammary carcinoma (CaNT), and 3% DFMO in the drinking water was provided once the tumours were established. Over a 10-day period control SaF tumours increased exponentially from 20 mm3 to over 800 mm3, whereas DFMO-treated SaF reached only 300 mm3. CaNT grew more slowly, requiring 22 days to achieve a similar volume increase, and DFMO was as effective in retarding growth as it had been in SaF. DFMO depleted tumour tissues of putrescine and spermidine, but did not reduce spermine levels. Metaphase arrest experiments with vincristine demonstrated that DFMO could substantially reduce the rates of tumour cell production, but there was no indication the DFMO accelerated the rate of cell loss from the tumours. Despite reduced rates of cell production, labelling studies with bromodeoxyuridine failed to detect differences between control and treated tumours: an increase in transit time through the S-phase was suspected. The number of nuclear organizer regions, detected by the argyrophilia of their associated proteins, was less in DFMO-treated tumours, and within a tumour the degree of silver deposition unequivocally reflected the proliferative heterogeneity. Ultrastructural studies revealed no differences between DFMO-treated and untreated tumours.

Conference Abstract| October 01 1990 Exogenous Polyamines (PAs) and Small Bowel Transport: In Vitro Studies in the Rat K. Hinuma; K. Hinuma 1Gastroenterology Unit, Guy's Campus, UMDS, London SE1 9RT, England Search for other works by this author on: This Site PubMed Google Scholar M. Maghsoudloo; M. Maghsoudloo 1Gastroenterology Unit, Guy's Campus, UMDS, London SE1 9RT, England Search for other works by this author on: This Site PubMed Google Scholar GM Murphy; GM Murphy 1Gastroenterology Unit, Guy's Campus, UMDS, London SE1 9RT, England Search for other works by this author on: This Site PubMed Google Scholar RH Dowling RH Dowling 1Gastroenterology Unit, Guy's Campus, UMDS, London SE1 9RT, England Search for other works by this author on: This Site PubMed Google Scholar Clin Sci (Lond) (1990) 79 (s23): 2P. https://doi.org/10.1042/cs079002Pa Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter LinkedIn Cite Icon Cite Get Permissions Citation K. Hinuma, M. Maghsoudloo, GM Murphy, RH Dowling; Exogenous Polyamines (PAs) and Small Bowel Transport: In Vitro Studies in the Rat. Clin Sci (Lond) 1 October 1990; 79 (s23): 2P. doi: https://doi.org/10.1042/cs079002Pa Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search nav search search input Search input auto suggest search filter All ContentAll JournalsClinical Science Search Advanced Search This content is only available as a PDF. © 1990 The Biochemical Society and the Medical Research Society1990 Article PDF first page preview Close Modal You do not currently have access to this content.

The enzyme diamine oxidase (DAO) is almost exclusively confined to the intestinal mucosa where it plays important roles in the metabolism of the poly-amines and the degradation of histamine (histami-nase). Unstimulated plasma DAO is close to assay detection limits but the enzyme can be released into the circulation by low-dose (5,000 U) i.v. heparin. The resultant area under the plasma concentration-time curve (AUC: measured every 15 min for 2 h) correlates linearly with intestinal mucosal DAO activity (Rokkas et al, Gut 1986;27:A630) suggesting that the AUC provides a noninvasive marker of intestinal DAO activity. Patients with chronic idiopathic urticaria ( ± intestinal mucosal oedema and colic) are intolerant of exogenous i.v. histamine and degrade it more slowly than controls [Murdoch et al, Clin Exp Allergy 1989; 19:103]. Histamine is catabolised mainly by histaminase ± prior hepatic methylation. We postulated, therefore, that the slow degradation of infused histamine in urticaria patients might be due to a deficiency of intestinal mucosal DAO. To test this hypothesis, we measured post-heparin plasma DAO profiles in 17 controls and 14 patients with chronic ( > 3 months) recurrent ( > 5 attacks) urticaria. The mean AUC in the patients (16.9 ± SD 13.3 mU·l”1 ×h) was significantly (p < 0.002) less than that in the controls (35.8 ± 20.8). Despite the scatter of results, six of the 14 patients had little or no rise in plasma DAO after the i.v. heparin and no overlap in AUCs with the controls. To confirm that the low AUCs in these patients did indeed reflect intestinal mucosal DAO deficiency, 6 of the 14 consented to peroral jejunal biopsies. Four had virtually no mucosal DAO activity (0.7-1.2 mU/g mucosal protein) compared with that in controls (22.4 ± 16.4) but in the remaining two, DAO levels (16 and 53 mU/g) were in the normal range. Moreover, when the results in the urticaria patients were added to our previous control data [Rokkas et al, 1986], the significance of the linear regression correlating post-heparin plasma and jejunal mucosal DAO activity was maintained (r=0.84;p < 0.01). Conclusion: In some, but not all, patients with chronic urticaria ± recurrent abdominal colic, the associated defect in histamine degradation seems to be due to intestinal mucosal DAO deficiency. Thus patients with urticaria may have a newly-recognised, primary intestinal disease.