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Hnatiuk OW, Moores LK, Thompson JC, Jones MD. Delivery of high concentrations of inspired oxygen via Tusk mask. Crit Care Med 1998; 26:1032-5. [PMID: 9635651 DOI: 10.1097/00003246-199806000-00022] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
OBJECTIVES Nonrebreather face masks (NRM) are frequently used in patients with respiratory distress and profound hypoxemia. A simpler modification to the partial rebreather face mask, using only two pieces of respiratory tubing or "tusks," has also been shown to increase FiO2 compared with the NRM in five normal subjects. Clinically, we have observed this modification to further increase PaO2 in critically ill patients already using the NRM in the intensive care unit. This study was designed to compare the Tusk mask with the NRM in both a larger group of normal subjects and in patients with underlying lung disease. DESIGN Prospective, randomized, crossover study. SETTING A university teaching hospital and tertiary care referral center. SUBJECTS Sixteen normal subjects (11 male and 5 female; age 30.4+/-6.8 [SD] yrs) and seven patients with interstitial lung disease (ILD) (3 male and 4 female; age 68.1+/-11.9 yrs). INTERVENTIONS Subjects and patients served as their own controls and were randomized to wear either the NRM or Tusk mask for a 30-min period. After a 60-min washout period, the other mask was applied. MEASUREMENTS AND MAIN RESULTS Arterial blood gas measurements were performed immediately before and at the end of each 30-min test period. Respiratory synchronization during the study period was achieved, using a metronome. In the normal subjects, PaO2 using the NRM and Tusk masks increased 290.0+/-57.1 torr (38.6+/-7.6 kPa) and 330.0+/-68.9 torr (44.0 +/-9.2 kPa), respectively (p=.032). PaO2 increased 293.4+/-38.0 torr (39.1+/-5.1 kPa) with the NRM and 378.4+/-61.7 torr (50.4+/-8.2 kPa) with the tusk mask (p=.001) in the patients with ILD. There was no statistically significant change seen in mean PaCO2 with either mask in either group. The mean PaO2 returned to within 6% of baseline in both groups after the washout period. CONCLUSIONS Both normal subjects and patients with compromised pulmonary function achieved a higher PaO2 using a Tusk mask than when using the conventional NRM, at the same oxygen flow rate. Patients with hypoxemia may obtain lifesaving benefit from the additional concentration of oxygen delivered via the Tusk mask.
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Guo YS, Jin GF, Houston CW, Thompson JC, Townsend CM. Insulin-like growth factor-I promotes multidrug resistance in MCLM colon cancer cells. J Cell Physiol 1998; 175:141-8. [PMID: 9525472 DOI: 10.1002/(sici)1097-4652(199805)175:2<141::aid-jcp3>3.0.co;2-o] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Insulin-like growth factor-I (IGF-I) is known as a potent mitogen for a variety of cell types, including colon cancer cell lines. The objective of this study was to determine the effect of IGF-I on cell death induced by cytotoxic agents actinomycin D (Act-D), lovastatin (LOV), and doxorubicin (DOX) in the MCLM mouse colon cancer cell line, and the mechanisms involved. Subconfluent monolayer MCLM cells were treated with IGF-I (25 ng/ml) for 12 h in serum-free media. Various concentrations of cytotoxic agents then were added to the cells that were incubated continually at 37 degrees C for 24 h. Cell survival was determined with the MTT (3-[4-5-dimenthylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assay, which assesses mitochondrial function in living cells. The mRNA expression for multidrug resistance gene-1 (mdr-1), c-H-ras, and manganese superoxide dismutase (MnSOD) in cells treated with IGF-I was examined by Northern blot or RNase protection assays. The levels of p-glycoprotein, a drug efflux pump encoded by the mdr-1 gene, were assessed by Western immunoblotting. Results demonstrated that 1) IGF-I significantly inhibited the cell death and apoptosis of MCLM cells treated with Act-D, LOV, or DOX; 2) IGF-I increased mRNA expression for mdr-1, c-H-ras, and MnSOD; 3) the p-glycoproteins in cells treated with IGF-I or stably transfected with c-H-ras were elevated when compared with control. These results suggest that IGF-I protects MCLM cells against death induced by cytotoxic agents; this acquired drug resistance may be mediated by multiple mechanisms, including promoting expression of mdr-1, c-H-ras, and MnSOD; whereas, the p-glycoprotein level stimulated by IGF-I may result partly from the increase of c-H-ras in the cells.
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Thompson JC, Thornton RN, Bruere SN, Ellison RS. Selenium reference ranges in New Zealand cattle. N Z Vet J 1998; 46:65-7. [PMID: 16032018 DOI: 10.1080/00480169.1998.36058] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
AIM To compare serum selenium and liver selenium concentrations with whole blood concentrations in samples taken at the same time from unsupplemented cattle, and to use these comparisons to establish a reference range for use in diagnosing selenium deficiency. METHODS Selenium was measured in concurrent whole blood, serum and liver samples obtained from cattle in unsupplemented herds in the Manawatu, Waikato and Wairarapa regions of New Zealand. The results were statistically analysed. RESULTS The revised reference ranges are as follows. [table: see text] CONCLUSION The serum and liver selenium concentrations used as reference values prior to this study were inaccurate for the detection of selenium deficiency.
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Tarasova N, Spannagel AW, Green GM, Gomez G, Reed JT, Thompson JC, Hellmich MR, Reeve JR, Liddle RA, Greeley GH. Distribution and localization of a novel cholecystokinin-releasing factor in the rat gastrointestinal tract. Endocrinology 1997; 138:5550-4. [PMID: 9389543 DOI: 10.1210/endo.138.12.5554] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The purpose of this study was to examine the distribution and localization of an intestinal cholecystokinin (CCK)-releasing factor, called luminal CCK-releasing factor (LCRF), in the gastrointestinal tract and pancreas of the rat. RIA analysis indicates that LCRF immunoreactivity is found throughout the gut including the pancreas, stomach, duodenum, jejunum, ileum, and colon with the highest levels in the small intestine. Immunohistochemistry analysis shows LCRF immunoreactivity staining in intestinal villi, Brunner's glands of the duodenum, the duodenal myenteric plexus, gastric pits, pancreatic ductules, and pancreatic islets. These results indicate potential sources for secretagogue-stimulated release of luminal LCRF and support the hypothesis that LCRF is secreted into the intestinal lumen to stimulate CCK release from mucosal CCK cells.
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Thompson JC, Craig AR, Davey CL, Newman DJ, Lonsdale ML, Bucher WJ, Nagle PD, Price CP. Kinetics and proposed mechanism of the reaction of an immunoinhibition, particle-enhanced immunoassay. Clin Chem 1997; 43:2384-9. [PMID: 9439458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We report kinetic studies on the reaction of a latex agglutination immunoassay used to quantify phenytoin in serum. In this assay, polystyrene particles with a covalently attached analog of phenytoin react with an antiphenytoin monoclonal antibody to form light-scattering aggregates, with the rate of this reaction being decreased by addition of phenytoin from sample. In the absence of free (sample) phenytoin, this reaction did not exhibit a maximum rate of agglutination in the presence of excess antibody, i.e., an equivalence point. Furthermore, agglutination was inhibitable by free phenytoin even when the latter was added after agglutination of particles with antibody had begun. Most significantly, the immunoagglutination proceeded in an identical fashion with monovalent F(ab) fragment. These data are consistent with low-affinity immunospecific particle-antibody complexation, which then induces colloidal aggregation, without requiring immunospecific bridging by antibody molecules. The described mechanism is not generalizable to all latex agglutination immunoassays, although disturbance of colloidal stability may be a component in most assays.
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Isenberg JI, Thompson JC. Medical progress and ulcer disease: three key observations that changed the compass. Gastroenterology 1997; 113:1031-3. [PMID: 9287999 DOI: 10.1016/s0016-5085(97)70201-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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Zhang P, Liégeois NJ, Wong C, Finegold M, Hou H, Thompson JC, Silverman A, Harper JW, DePinho RA, Elledge SJ. Altered cell differentiation and proliferation in mice lacking p57KIP2 indicates a role in Beckwith-Wiedemann syndrome. Nature 1997; 387:151-8. [PMID: 9144284 DOI: 10.1038/387151a0] [Citation(s) in RCA: 549] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Mice lacking the imprinted Cdk inhibitor p57(KIP2) have altered cell proliferation and differentiation, leading to abdominal muscle defects; cleft palate; endochondral bone ossification defects with incomplete differentiation of hypertrophic chondrocytes; renal medullary dysplasia; adrenal cortical hyperplasia and cytomegaly; and lens cell hyperproliferation and apoptosis. Many of these phenotypes are also seen in patients with Beckwith-Wiedemann syndrome, a pleiotropic hereditary disorder characterized by overgrowth and predisposition to cancer, suggesting that loss of p57(KIP2) expression may play a role in the condition.
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MESH Headings
- Abdomen
- Abnormalities, Multiple/embryology
- Abnormalities, Multiple/genetics
- Abnormalities, Multiple/pathology
- Adrenal Cortex/embryology
- Adrenal Cortex/pathology
- Animals
- Animals, Newborn
- Apoptosis
- Beckwith-Wiedemann Syndrome/genetics
- Beckwith-Wiedemann Syndrome/metabolism
- Beckwith-Wiedemann Syndrome/pathology
- Cartilage/cytology
- Cartilage/metabolism
- Cartilage/pathology
- Cell Differentiation
- Cell Division
- Crosses, Genetic
- Cyclin-Dependent Kinase Inhibitor p57
- Cyclin-Dependent Kinases/antagonists & inhibitors
- Enzyme Inhibitors
- Female
- Gene Expression
- Gene Targeting
- Hernia, Umbilical/embryology
- Hernia, Umbilical/genetics
- Hernia, Umbilical/pathology
- Kidney Medulla/embryology
- Kidney Medulla/pathology
- Lens, Crystalline/cytology
- Male
- Mice
- Mice, Inbred C57BL
- Muscle, Skeletal/embryology
- Muscle, Skeletal/pathology
- Nuclear Proteins/genetics
- Nuclear Proteins/physiology
- Osteogenesis
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Iwase K, Evers BM, Hellmich MR, Kim HJ, Higashide S, Gully D, Thompson JC, Townsend CM. Inhibition of neurotensin-induced pancreatic carcinoma growth by a nonpeptide neurotensin receptor antagonist, SR48692. Cancer 1997; 79:1787-93. [PMID: 9128997 DOI: 10.1002/(sici)1097-0142(19970501)79:9<1787::aid-cncr22>3.0.co;2-t] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
BACKGROUND Recently, a nonpeptide neurotensin (NT) receptor antagonist, SR48692, was developed that selectively antagonizes the high affinity, biologically active NT binding site. The effect of SR48692 on NT-mediated growth of a human pancreatic carcinoma, MIA PaCa-2, was determined both in vitro and in vivo. METHODS (125)I-NT binding and Northern blot analyses were performed for evaluation of the NT receptor in MIA PaCa-2 cells. Intracellular calcium ([Ca2+]i) mobilization and inositol phosphate (IP3) levels were measured. Cell growth studies were performed by counting cell numbers. Athymic nude mice were inoculated with MIA PaCa-2 cells and randomized into four groups to receive either vehicle (NT or SR48692) or NT + SR48692. RESULTS MIA PaCa-2 cells possess both a high affinity, SR48692-sensitive and a levocabastine-insensitive NT binding site; Northern blot analysis demonstrated expression of the NT receptor. SR48692 inhibited [Ca2+]i mobilization, IP3 turnover, and MIA PaCa-2 cell growth induced by NT in a dose-dependent fashion. In in vivo experiments, NT significantly increased the size, weight, and DNA and protein content of xenografted MIA PaCa-2 tumors; SR48692 inhibited the effect of NT. CONCLUSIONS The novel NT receptor antagonist SR48692 will be a valuable agent to delineate further the cellular mechanisms responsible for peptide-mediated growth of normal and neoplastic gut tissues.
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MESH Headings
- Animals
- Binding Sites
- Calcium/metabolism
- Cell Division/drug effects
- Drug Interactions
- Humans
- Hydrolysis
- Intestine, Small/cytology
- Intestine, Small/drug effects
- Male
- Mice
- Mice, Inbred BALB C
- Mice, Nude
- Neoplasm Transplantation
- Neurotensin/antagonists & inhibitors
- Neurotensin/pharmacology
- Pancreatic Neoplasms/metabolism
- Pancreatic Neoplasms/pathology
- Pancreatic Neoplasms/ultrastructure
- Phosphatidylinositol 4,5-Diphosphate/metabolism
- Pyrazoles/pharmacology
- Quinolines/pharmacology
- RNA, Messenger/metabolism
- Receptors, Neurotensin/antagonists & inhibitors
- Receptors, Neurotensin/metabolism
- Transplantation, Heterologous
- Tumor Cells, Cultured/drug effects
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Thompson JC. Private finance/going live. Eastern promise. THE HEALTH SERVICE JOURNAL 1997; 107:suppl 12-4. [PMID: 10165891] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
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Higashide S, Chu KU, Gomez G, Greeley GH, Thompson JC, Townsend CM. Caloric restriction causes secretagogue specific changes of gastric acid secretion in rats. REGULATORY PEPTIDES 1997; 68:205-10. [PMID: 9100288 DOI: 10.1016/s0167-0115(96)02124-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The purpose of this study was to examine the effects of short-term caloric restriction (CR) for 4, 8 and 16 weeks on gastric acid secretion in rats. CR rats fed 60% of normal food intake for 4, 8 or 16 weeks and then prepared with gastric fistulas. Histamine- and carbachol-stimulated gastric acid secretion were significantly (P < 0.05) decreased after more than 4 weeks and 8 weeks of caloric restriction, respectively. In contrast, gastrin-stimulated acid secretion was unaffected by CR. The 1-h-integrated acid output to a submaximal dose of gastrin (40 micrograms.kg-1) was significantly higher than that of histamine (5 mg.kg-1) after 8 weeks of CR (63 +/- 13 and 27 +/- 4 microEq.h-1, respectively). Gastrin treatment (5 micrograms.kg-1.h-1) of CR rats restored the gastric acid responses to both histamine and carbachol. These results suggest that CR can selectively decrease the gastric acid responses to both histamine and carbachol by depletion of the endogenous tissue stores of gastrin. More importantly, these results indicate that under an in vivo gastrin-diminished condition, histamine is not the final secretagogue for gastric acid secretion.
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Thompson JC, Ellison RS, Kirk J. Serum thyroid hormone concentrations in New Zealand horses. N Z Vet J 1997; 45:11-4. [PMID: 16031941 DOI: 10.1080/00480169.1997.35981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Total thyroxine and total tri-iodothyronine concentrations were measured in the sera from 125 horses of mixed age, breed and sex, and varied clinical histories. While low serum thyroxine concentrations were detected in 35 horses, the majority of those horses had serum thyroxine values within the reference range when retested. Only one horse had a mildly decreased serum tri-iodothyronine concentration. Those horses in which the serum thyroxine concentration was low when retested had a normal thyrotropin releasing hormone stimulation test. Hypothyroidism was not diagnosed in any horses in this study. The low serum thyroxine concentrations measured in the present study were attributed to either normal fluctuations in serum concentrations in healthy horses, the effect of drugs, or to the effects of non-thyroidal illness. Because thyroid hormone concentrations are altered by many factors, hypothyroidism should not be diagnosed on the basis of a single low value and further testing, preferably including active stimulation of the thyroid gland, should be carried out.
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Gomez G, Lambertz I, Udupi V, Qi X, Thompson JC, Greeley GH. Influence of nicotine on gastrin and peptide YY in the rat. REGULATORY PEPTIDES 1996; 67:55-61. [PMID: 8952006 DOI: 10.1016/s0167-0115(96)00107-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The objective of this study was to examine the effects of nicotine and high-fat diets on gastrin and peptide YY (PYY) homeostasis in the rat. Antral levels of gastrin mRNA and peptide and ileal and colonic levels of PYY mRNA and peptide were examined. Serum levels of gastrin in response to food were also measured. Control rats were ad-lib fed or pair-fed according to the daily food intake of nicotine-treated rats. The results of this study indicate that nicotine treatment and fat diets can influence gastrin and PYY gene expression in the gastrointestinal tract.
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Chu KU, Ishizuka J, Battey JF, Uchida T, Beauchamp RD, Townsend CM, Thompson JC. Mechanisms of bombesin on growth of gastrinoma (PT) in vivo. Dig Dis Sci 1996; 41:2180-6. [PMID: 8943970 DOI: 10.1007/bf02071398] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The growth of the human gastrinoma model (PT) in athymic nude mice is stimulated by bombesin (BBS), an amphibian peptide homologous to both human gastrin-releasing peptide (GRP) and neuromedin B (NMB). The mechanism is not known, and a potent and specific GRP-R antagonist BIM26226, which has low affinity for NMB-R, was used in vivo in athymic nude mice bearing gastrinoma subcutaneously. Both the BBS and BIM26226 stimulated the growth of PT, and the growth stimulation was even greater when given together. RT-PCR study of gastrinoma revealed the presence of both GRP-R and NMB-R mRNA, but much more abundant NMB-R mRNA. We conclude that BBS-stimulated growth of gastrinoma involves both GRP-R and NMB-R, and our findings suggest that GRP-R mediates negative and NMB-R produces positive growth effects on gastrinoma.
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Hirai A, Bold RJ, Ishizuka J, Hirai M, Townsend CM, Thompson JC. Hyperphosphorylation of retinoblastoma protein and stimulation of growth by okadaic acid in human pancreatic cancer. Dig Dis Sci 1996; 41:1975-80. [PMID: 8888710 DOI: 10.1007/bf02093599] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Phosphorylation/dephosphorylation of intracellular proteins are important steps in the regulation of cell growth. Okadaic acid, an inhibitor of the serine/threonine protein phosphatases 1 and 2A, is a potent tumor promoter. This effect may be through the inhibition of dephosphorylation (termed "hyperphosphorylation") and subsequent inactivation of tumor-suppressor proteins. We examined whether okadaic acid regulates growth of human pancreatic cancer cells (MIA PaCa-2 and Panc-1) or alters the phosphorylation of the retinoblastoma tumor-suppressor protein. Growth studies, nuclear labeling analyses, and Western blotting for retinoblastoma protein were performed. Okadaic acid stimulated cell growth and induced hyperphosphorylation of the retinoblastoma protein. The growth-stimulatory effect of okadaic acid on these human pancreatic cancer cells may be mediated by inactivation of the growth suppressive effect of the retinoblastoma protein by hyperphosphorylation. These studies suggest that the growth of these human pancreatic cancer cells is still regulated by tumor-suppressor proteins.
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Gomez G, Udupi V, Qi X, Lluis F, Rajaraman S, Thompson JC, Greeley GH. Growth hormone upregulates gastrin and peptide YY gene expression. THE AMERICAN JOURNAL OF PHYSIOLOGY 1996; 271:E582-6. [PMID: 8843754 DOI: 10.1152/ajpendo.1996.271.3.e582] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The purpose of these studies was to examine the effects of excess growth hormone (GH) on gastrin and peptide YY (PYY) gene expression. Transgenic mice with the bovine GH gene linked to a mouse metallothionein I promoter were used as a model of chronic GH excess. Antral gastrin mRNA and peptide levels were elevated significantly (P < 0.05) in GH transgenic mice compared with wild type littermates. Ileal PYY mRNA and ileal and colonic PYY levels were significantly elevated in GH transgenic mice compared with wild type littermates. The elevations in gastrin and PYY gene expression in GH transgenic mice were independent of food intake. Serum concentrations of gastrin and PYY were also elevated in GH transgenic mice. Immunohistochemical analysis showed that the density of PYY-containing cells in the colon of GH transgenic mice and wild type littermates did not differ. In addition, the mRNA and protein levels of chromogranin A, a marker of endocrine cells, were not increased in the colon of GH transgenic mice. Together, these data indicate that GH, insulin-like growth factor I, or both can upregulate gastrointestinal gastrin and PYY gene expression directly.
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Yoshinaga K, Ishizuka J, Gomez G, Izukura M, Townsend CM, Mishima Y, Thompson JC. Stimulation of pancreatic growth. Distal small bowel resection mediated by increased levels of cholecystokinin. Ann Surg 1996; 224:139-44. [PMID: 8757376 PMCID: PMC1235334 DOI: 10.1097/00000658-199608000-00005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
SUMMARY BACKGROUND DATA Distal, but not proximal, resection of the small bowel induces growth of rat pancreas, but the mechanism of this phenomenon is poorly clarified. The release of cholecystokinin (CCK), a trophic hormone for the pancreas, is regulated by a negative-feedback control of bile salts. The ileum is a major site for reabsorption of bile salts. Thus, unsuppressed release of CCK due to deleted reabsorption of bile salts after distal small bowel resection may be a cause of pancreatic growth. In this study, the authors have examined whether pancreatic growth after distal small bowel resection was mediated by endogenous CCK and have determined whether the mechanism of this pancreatic growth required biosynthesis of polyamine. METHODS Male Fischer 344 rats underwent 70% distal small bowel resection or transection of the ileum. Beginning 48 hours after surgery, CR1409 (a CCK-receptor antagonist) or saline was injected subcutaneously every 8 hours. All animals were pair-fed and killed 14 days after surgery. The pancreas from each rat was excised, weighed, and assayed for DNA, RNA, protein, and polyamine content. RESULTS Distal small bowel resection increased pancreatic weight, DNA, RNA, and protein, as well as polyamine levels; all of these increases were significantly suppressed by CR1409. Postprandial release of CCK into the circulation was significantly increased after distal small bowel resection. CONCLUSIONS Pancreatic growth after distal small bowel resection was associated with the stimulation of polyamine biosynthesis; growth appeared to be mediated by endogenous CCK.
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Chu KU, Evers BM, Ishizuka J, Beauchamp RD, Greeley GH, Townsend CM, Thompson JC. Short-term caloric restriction augments age-related decreases in gastrin content and release. Mech Ageing Dev 1996; 87:25-33. [PMID: 8735904 DOI: 10.1016/0047-6374(96)01695-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Aging is associated with significant structural and functional changes in the gastrointestinal tract. Gastrin, a hormone produced by G cells in the antrum of the stomach, stimulates proliferation of gastric mucosa; its synthesis appears to decrease with age. Life-long restriction of caloric intake is the only experimental manipulation that has been shown to retard aging processes in rats. The purpose of this study was to examine the effect of short-term caloric restriction (CR) on the production and release of the hormone gastrin with aging. Aging causes a fall in both fasting plasma levels of gastrin and antral content of gastrin in Fischer 344 rats; short-term CR appears to augment this age-related decrease. Steady state levels of antral gastrin mRNA were decreased with aging, and short-term CR resulted in an augmented decrease in aged, but not in young rats. Our findings indicate that gastrin release, synthesis and gene expression decrease with age. Restriction of the caloric intake for a short period (i.e. 8 weeks) augments this age-related decrease in antral gastrin and fasting plasma levels. Short-term CR appears to decrease the production of gastrin at the level of gene expression.
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Glass KL, Dillard TA, Phillips YY, Torrington KG, Thompson JC. Pulse oximetry correction for smoking exposure. Mil Med 1996; 161:273-6. [PMID: 8855058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Pulse oximetry oxygen saturation (SpO2) does not distinguish carboxyhemoglobin (COHb) from oxyhemoglobin (O2Hb), giving a false impression of the apparent degree of oxyhemoglobin saturation in smokers who have elevated levels of COHb. We questioned whether accounting for smoking exposure history could improve description of pulse oximetry by correcting for COHb levels. We evaluated smoking history and %SpO2 as predictors of %O2Hb and %COHb by CO-oximetry of arterial blood in 18 actively smoking and 18 age-matched nonsmoking patients in a clinical pilot study. The difference between %SpO2 and %O2Hb was significantly greater (p < 0.001) in the smokers (5.6 +/- 3.1) than the nonsmokers (2.1 +/- 2.1). This difference correlated with %COHb (rp = 0.789; p < 0.001) and the smoking exposure score (SES, rp = 0.621; p < 0.001), a six-point index we developed based on whether patients were active smokers, refrained from smoking prior to testing, or were exposed to passive smoking in the home or workplace. The following formula summarizes the correction: %O2Hb = 0.882[%SpO2] - 0.968[SES] + 9.245 (rp = 0.841; SES = 2.478; p < 0.001). This pilot study suggests that smoking exposure history correlates with COHb levels and that correction for smoking exposure improves the accuracy of pulse oximetry.
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Evers BM, Zhou Z, Dohlen V, Rajaraman S, Thompson JC, Townsend CM. Fetal and neoplastic expression of the neurotensin gene in the human colon. Ann Surg 1996; 223:464-70; discussion 470-1. [PMID: 8651737 PMCID: PMC1235163 DOI: 10.1097/00000658-199605000-00002] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
OBJECTIVE The authors identified various colon cancers that express the gene for the gut peptide neurotensin (NT/N). In addition, the authors sought to delineate the temporal pattern of NT/N gene expression in the human fetal colon. SUMMARY BACKGROUND DATA Expression of NT/N is localized to the mucosa of the adult small bowel but also has been identified in the fetal colon, which resembles the small bowel until the end of the second trimester. Ectopic NT/N expression has been shown in certain types of colon cancer, suggesting a reversion to a fetal phenotype. METHODS Sensitive ribonuclease protection assays were used to determine NT/N expression in colon cancers and adjacent normal mucosa as well as colon cancers established as tumor xenografts and fetal colon samples. RESULTS NT/N gene expression was shown in 4 of 12 (25%) human colon cancer xenografts and in 11 of 40 (28%) freshly resected colon adenocarcinomas; NT/N gene expression was not expressed in any of the samples of normal colonic mucosa adjacent to the tumors. The NT/N gene was expressed maximally in the fetal colon between 16 and 18 weeks' gestation; NT/N expression was decreased between 19 and 22 weeks and was not apparent in either the 24-week fetal colon or the adult samples. CONCLUSIONS The NT/N gene expression is expressed transiently in the fetal colon during a development stage that is characterized by morphologic similarity to the small bowel. In addition, NT/N is reexpressed in approximately one fourth of the human colon cancers, indicating that neoplastic transformation leads to reversion to a fetal phenotype in certain types of colon cancer. The NT/N gene will provide a useful model to further define the complex differentiation pathways in the normal gut as well as the process of fetal "dedifferentiation" in certain types of colon cancer.
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Ehrenfried JA, Evers BM, Chu KU, Townsend CM, Thompson JC. Caloric restriction increases the expression of heat shock protein in the gut. Ann Surg 1996; 223:592-7; discussion 597-9. [PMID: 8651750 PMCID: PMC1235189 DOI: 10.1097/00000658-199605000-00015] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
OBJECTIVE The authors determined whether caloric restriction (CR) either acutely or chronically, alters heat shock protein 70 (hsp70) gene expression in the gut. SUMMARY BACKGROUND DATA Caloric restriction prolongs the life span and delays age-related disease (e.g., cancer) in mammals; the mechanisms responsible for these effects are not known. Heat shock proteins are a group of stress-responsive genes of which the most prominent member is hsp70. METHODS In the first experiment, adult (4-month-old) rats (n = 3/group) were killed after a 48-hour fast or 6 and 24 hours after refeeding. In addition, three rats (controls) were killed without fasting or refeeding. The stomach was removed and RNA was extracted for hsp70 gene expression. In the second experiment, aged (22- to 26-month-old) rats were fed ad libitum (AL) or a CR diet (60% caloric intake of AL diet). Rats were killed, the stomach and duodenum were removed, and RNA was extracted for determination of hsp70 gene expression. RESULTS In the first experiment, hsp70 mRNA levels were increased approximately threefold in the stomach of rats fasted for 48 hours; levels decreased to control values by 6 and 24 hours after refeeding. In the second experiment, hsp70 mRNA levels were increased significantly in both the stomach and duodenum of aged CR rats compared with AL controls. CONCLUSIONS The authors have demonstrated that hsp70 mRNA levels are increased in the proximal gut of young and old rats, either acutely (with fasting) or with CR. Increased expression of the cytoprotective hsp70 gene in the gut may provide a possible cellular mechanism for the beneficial effects noted with CR.
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Gomez G, Padilla L, Udupi V, Tarasova N, Sundler F, Townsend CM, Thompson JC, Greeley GH. Regulation of peptide YY homeostasis by gastric acid and gastrin. Endocrinology 1996; 137:1365-9. [PMID: 8625912 DOI: 10.1210/endo.137.4.8625912] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Peptide YY (PYY) is a gut hormone localized primarily in the distal bowel. Because circulating PYY inhibits gastric acid secretion, we investigated the effects of gastric acid secretion and gastrin on gene expression and secretion of PYY. In conscious dogs, PYY release in response to oral food was inhibited (P < 0.05) by pharmacologic inhibition of gastric acid secretion (omeprazole, famotidine). In rats, omeprazole treatment resulted in a significant elevation in serum gastrin concentrations and a simultaneous decrease in PYY messenger RNA (mRNA) and peptide levels in the colon; administration of a gastrin receptor antagonist (L365, 260) prevented the inhibitory actions of omeprazole on colonic PYY mRNA levels. In athymic-nude mice, implantation of a human gastrinoma resulted in an elevation of serum gastrin concentrations and a concomitant depression of colonic PYY mRNA levels. We conclude that endogenous gastric acid secretion up-regulates PYY release and PYY mRNA expression. Circulating gastrin acts to down-regulate PYY release and PYY mRNA expression. This study provides evidence that foregut functions (i.e., gastric acid secretion and gastrin release) exert control over an antiacid signal (e.g. PYY release) emanating from the hindgut.
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Abstract
Retinoids are a class of molecules structurally related to vitamin A that have potent antiproliferative and differentiating effects on a variety of normal and neoplastic tissues. All-trans-retinoic acid (ATRA) has become a first-line chemotherapeutic agent in the treatment of certain leukemias; however, the effect of ATRA on pancreatic tumors is unknown. The purpose of this study was to determine the effect of ATRA on the growth characteristics of both exocrine and endocrine human pancreatic cancer cell lines. The in vitro growth of four cell lines was examined after treatment with a wide dose range of ATRA. The growth of all tumor cell lines was inhibited by ATRA in a dose-dependent fashion beginning at 0.1 microgram M. The in vivo growth of functioning human pancreatic carcinoid (BON) xenografts in Balb/c athymic mice was determined by treatment with several doses of ATRA over 1 month. The growth of BON tumors was inhibited in a dose-dependent fashion. These results suggest that ATRA exerts direct antiproliferative effects on both exocrine and endocrine human pancreatic cancers and may be useful in the chemotherapy of these tumors.
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Thompson JC, Kosmorsky GS, Ellis BD. Field of dreamers and dreamed-up fields: functional and fake perimetry. Ophthalmology 1996; 103:117-25. [PMID: 8628542 DOI: 10.1016/s0161-6420(96)30751-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
PURPOSE Hysterical and malingering patients can manifest visual field defects on perimetry (visual field testing), including defects suggestive of true visual pathway pathology. It has been shown that control subjects can easily imitate some pathologic defects with automated, computed perimetry. The authors sought to determine whether subjects could imitate the same pathologic defect with manual and automated perimetry. METHOD Six subjects posed as patients with neurologic problems. They had manual perimetry with both an experienced and inexperienced technician followed by automated perimetry. They were later interviewed about the methods of the technicians and the difficulty of the exercise. RESULTS Four of six subjects easily imitated the assigned defects with both technicians on manual perimetry and with automated perimetry. These included quadrantic, altitudinal, hemianopic, and enlarged blind-spot defects. Two subjects who were assigned cecocentral and paracentral scotomas instead produced enlarged blind spots by manual perimetry and defects suggestive of chiasmal pathology by automated perimetry. Paradoxically, some subjects found that experienced technicians were easier to fool than inexperienced technicians because of the systematic way in which experienced technicians defined defects. CONCLUSIONS With minimal coaching, some subjects can imitate visual fields with enlarged blind spots, quadrantic, hemianopic, and altitudinal defects with ease and reproducibility by both automated and manual perimetry. Cecocentral and paracentral scotomas are harder to imitate but may be mistaken as representing chiasmal pathology. Paradoxically, experienced technicians may not be better at detecting hysterical or malingering individuals.
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Yao CZ, Ishizuka J, Bold RJ, Sperling HE, Townsend CM, Thompson JC. Human monoclonal antibody against colon cancer. Cancer Invest 1996; 14:211-7. [PMID: 8630681 DOI: 10.3109/07357909609012141] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The purpose of the study was to produce human monoclonal antibodies (hMcAb) against human colon cancer for use in radioimmunoimaging. Human-mouse heterohybridomas were developed by fusing SHM-D33 mouse-human hybrid heteromyeloma cells with human lymphocytes from colon cancer tumor-draining lymph nodes. The hybridomas capable of secreting human monoclonal antibodies were screened by using human colon cancer cell lines and pathological biopsies with ELISA and immunohistochemical methods. hMcAb clone H11 was selected for a large-scale antibody production, which was purified from mouse ascites. Biodistribution study demonstrated that specific uptake of 125I-hMcAb H11 by human colon cancer xenografts was significantly higher than by normal tissues. Radioimmunoimaging of human colon cancer xenografts exhibited distinct tumor visualization during the period of 72-96 hr after intraperitoneal injection of 125I-hMcAb H11. The development of human monoclonal antibodies such as hMcAb H11 may be useful for radioimmunodetection and therapy of colon cancer.
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