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  • radioimmunoassay  (2)
  • α-difluoromethylornithine  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Characterization of secretin release in response to food and intraduodenal administration of fat and hydrochloric acid (1991)
    Springer
    Digestive diseases and sciences 36 (1991), S. 513-519 
    Details
    ISSN: 1573-2568
    Keywords: gastrointestinal hormone ; radioimmunoassay ; secretagogues ; duodenal acidification ; pancreatic bicarbonate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The development and validation of a radioimmunoassay that detects release of secretin in plasma in response to low doses of secretagogues [intraduodenal HCl (0.033 meq/min); intraduodenal sodium oleate (0.04 mmol/min)] or an oral mixed meal in conscious dogs is described. Plasma secretin levels increased significantly (P〈0.05) in response to an oral mixed meal in conscious dogs from a basal level of 4.0 to a peak level of 12.3 pg/ml at 15 min. Infusion of graded doses of HCl (2, 4, 8, 16, meq/hr for 30 min) intraduodenally in six dogs resulted in significant elevation of plasma secretin levels in a dose-dependent manner. The pancreatic bicarbonate and volume outputs correlated with the dosage of HCl administered and with the elevations in plasma secretin concentrations. Intraduodenal infusion of increasing doses of sodium oleate (2.4, 4.8, 9.6, and 19.2 mmol in 15-min periods) resulted in a significant (P〈0.05) elevation of plasma levels of secretin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01298885
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Effect of oral fat on plasma levels of neurotensin and neurotensin fragments in humans (1990)
    Springer
    Digestive diseases and sciences 35 (1990), S. 200-204 
    Details
    ISSN: 1573-2568
    Keywords: high-pressure liquid chromatography ; neurotensin ; peptide ; radioimmunoassay
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effect of ingestion of fat (Lipomul 1 g/kg) on the circulating levels of neurotensin (NT1–3) and amino-terminal fragments (NT1–8, NT1–11) and carboxy-terminal fragment (NT8–13) of NT were investigated in six healthy male volunteers. NT and NT fragments were extracted from plasma collected at 0, 15, 30, and 60 min after ingestion of fat, and the plasma levels of NT1–13 and NT fragments were characterized using high-pressure liquid chromatography and radioimmunoassay techniques. Significant elevations of plasma levels of NT1–8, NT1–11, and NT1–13 were observed at 15, 30, and 60 min after fat ingestion. The maximum elevations were 273% for NT1–8, 234% for NT1–11, and 54% for NT1–13. NT8–13 levels failed to rise significantly when compared to basal levels. These findings indicate that both the aminoterminal and carboxyterminal fragments of NT are either released along with intact NT or are formed as metabolites from NT1–13 in response to ingestion of fat in man.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01536763
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Cyclosporine and α-difluoromethylornithine exhibit differential effects on colon and pancreatic cancer in vitro (1987)
    Springer
    Investigational new drugs 5 (1987), S. 251-258 
    Details
    ISSN: 1573-0646
    Keywords: cancer ; cyclosporine ; pancreas ; colon ; polyamines ; α-difluoromethylornithine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract α-Difluoromethylornithine (DFMO) is a known irreversible inhibitor of ornithine decarboxylase (ODC), the rate-limiting enzyme in polyamine biosynthesis. Cyclosporine (CsA) has been reported to inhibit ODC activity in vitro. In the present study, we compared the effects of DFMO and CsA on growth, survival, and polyamine levels in mouse colon cancer (MC-26) and hamster pancreatic cancer (H2T) cells in vitro. The growth and survival of MC-26 and H2T cells were inhibited by both DFMO and CsA. However, H2T cells were observed to be significantly more sensitive than MC-26 cells to both CsA and DFMO. The inhibitory effects of CsA were blocked by the addition of the polyamine, putrescine, in both MC-26 and H2T cells. Polyamine levels were altered significantly in both MC-26 and H2T cells treated with CsA and DFMO. However, the profile of these alterations differed between MC-26 and H2T cell lines. Putrescine and spermidine levels in MC-26 cells were more sensitive to DFMO inhibition than were H2T cells. Spermine levels were consistently elevated in MC-26 cells exposed to CsA or DFMO, while the level of spermine in H2T cells decreased significantly in response to the same drugs. These results suggest that CsA and DFMO exhibit different effects on colon and pancreatic cancer growth in vitro. In addition, the differences in the sensitivity of pancreatic and colon cancer to CsA and DFMO indicate potentially important differences in polyamine metabolism between the two cell lines.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00175295
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    2-deoxy-D-glucose inhibits the antitumor effects of α-difluoromethylornithine on the growth of colon cancer in vivo (1989)
    Springer
    Investigational new drugs 7 (1989), S. 131-138 
    Details
    ISSN: 1573-0646
    Keywords: polyamines ; cancer ; 2-deoxy-D-glucose ; α-difluoromethylornithine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The glycolytic inhibitor, 2-deoxy-D-glucose (2-DG), has been shown to inhibit the growth of certain cancers. α-Difluoromethylornithine (DFMO) is an irreversible inhibitor of ornithine decarboxylase (ODC), the ratelimiting enzyme in polyamine biosynthesis. DFMO has been shown to inhibit cancer growth in a number of models. The present study was designed to investigate the effects of 2-DG alone and combined with DFMO on MC-26 mouse colon adenocarcinoma tumors growing in vivo. Twenty-eight male Balb/c mice were inoculated with 250,000 MC-26 cells, and then randomized into four groups of 7 each: group I served as control; group II received DFMO (3% in drinking water); group III received 2-DG (500 mg/kg/d IP); group IV received a combination of 2-DG and DFMO. Treatment began 5 days after tumor cell inoculation. MC-26 tumor area was reduced 73% by DFMO compared to a 24% reduction caused by 2-DG. The tumor weight was reduced 80% by DFMO and 52% by 2-DG. The tumor contents of DNA, RNA, and protein were significantly reduced by DFMO but not 2-DG. The tumor concentration of the polyamines putrescine and spermidine were reduced by DFMO alone or combined with 2-DG while spermine levels remained unchanged. 2-DG alone did not alter polyamine levels. These results indicate that both 2-DG and DFMO, when added as single agents, inhibit tumor growth. However, the addition of 2-DG to the DFMO regimen inhibited the antitumor effects of DFMO. Survival studies performed on MC-26 cells in vitro corroborated the antagonisms between DFMO and 2-DG that were shown in vivo.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00170849
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    Paper (German National Licenses)
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