Frequent loss of heterozygosity in human primary squamous cell and colon carcinomas at 7q31.1: evidence for a broad range tumor suppressor gene

Consistent deletions and loss of heterozygosity (LOH) in polymorphic markers in a determinate chromosomal fragment are known to be indicative of a closely mapping tumor suppressor gene. Deletion of the long arm of chromosome 7 is a frequent trait in many kinds of human primary tumors. We studied LOH of 14 markers on chromosome 7q in order to determine the location of a putative tumor suppressor gene in human primary squamous cell carcinoma of the head and neck and in human primary colon carcinomas. Samples were obtained from 18 primary squamous cell carcinomas of the head and neck and 18 primary colon carcinomas surgically removed from patients at the Fox Chase Cancer Center. Loss of heterozygosity was studied performing PCR amplifications of a set of 14 CA microsatellite repeats encompassing 7q21-qter. Of 18 squamous cell carcinomas of the head and neck cases studied, 12 had LOH at one or more loci on 7q. Fifty-three percent of 15 informative cases had LOH of the CA microsatellite dinucleotide repeat marker D7S522 at 7q31.1-7q31.2. Eleven of 18 colon carcinoma cases had LOH of one or more markers assayed, and the maximum LOH (80% of 10 informative cases) was at D7S522. Distributions of percentage of LOH in both tumor types were normally distributed around microsatellite D7S522. The high incidence of LOH in both tumor types studied suggests that a tumor suppressor gene relevant to the development of epithelial cancers is present on the 7q31.1-31.2, confirming our previous functional evidence for a tumor suppressor gene on chromosome 7.

Trophic response of gut and pancreas after ileojejunal transposition

OBJECTIVE

The authors determined whether ileojejunal transposition (IJT) stimulates the growth of the pancreas or the nontransposed segment of small intestine, and ascertained whether this trophic effect is altered by the location of transposed gut segment.

SUMMARY BACKGROUND DATA

Transposition of the ileum to the proximal small intestine stimulates a marked mucosal growth of the transposed ileal segment; the cellular mechanisms responsible for this adaptive hyperplasia are not known.

METHODS

The distal quarter of the small intestine (distal ileum) was transposed into the proximal (Type I), middle (Type II), or distal (Type III) portions of the remaining small intestine. On postoperative day 28, the pancreas and scraped mucosa from the segments of transposed ileum, proximal ileum, and duodenum were obtained, weighed, and examined for DNA and protein content.

RESULTS

All types of IJT increased mucosal weight and DNA content of the transposed ileum. Types I and II IJT produced a significant proliferation of the pancreas and mucosa of the duodenum and proximal ileum. The magnitude of proliferative increases was greatest in Type I IJT.

CONCLUSIONS

Ileojejunal transposition appears to be an excellent model to examine the mechanisms by which intestinal epithelial cells proliferate in response to luminal nutrients or humoral factors.

Observations on hypoglycaemia associated with a hepatoma in a cat

Disorientation, muscle fasciculations and weakness seen in a 12-year-old neutered female domestic shorthaired cat were attributed to hypoglycaemia associated with a large hepatoma. Glucagon tolerance tests on this cat and a healthy cat showed that their plasma glucose concentrations increased and decreased at about the same rate. Plasma insulin concentrations in the healthy cat increased and decreased in parallel with the plasma glucose concentration. In the affected cat, plasma insulin concentrations increased initially but decreased more rapidly. Reflecting these observations, the amended insulin to glucose ratios in the affected cat were much lower than those of the healthy cat, until the 4-hour sample. Serum somatostatin, somatomedin and gastrin concentrations were measured but no conclusions as to pathogenesis of the hypoglycaemia could be made. The alterations in insulin secretion in the affected cat suggested that altered hormonal control of glucose homeostasis may have occurred with this tumour.

Role of calcium in the regulation of ornithine decarboxylase enzyme activity in mouse colon cancer cells

Activity of ornithine decarboxylase (ODC), one of the rate-limiting enzymes in the pathway of polyamine biosynthesis, is regulated by various factors. In this study, we examined the role of Ca2+ in the regulation of ODC enzyme activity in mouse colon cancer cells (MC-26). KCl, a membrane-depolarizing agent that opens the voltage-dependent Ca(2+)-channel to increase intracellular Ca2+, decreased serum-induced ODC enzyme activity in MC-26 cells in a dose-dependent, reversible fashion. Both verapamil and nifedipine, inhibitors of the L-type voltage-dependent Ca(2+)-channel, decreased serum-induced ODC enzyme activity. W-7, a calmodulin inhibitor, decreased ODC enzyme activity in a dose-dependent, reversible fashion while trifluoperazine, another calmodulin inhibitor, failed to affect ODC enzyme activity in MC-26 cells. Our findings indicate that intracellular Ca2+ participates in the regulatory mechanism of ODC enzyme activity in MC-26 cells, although the exact role of Ca2+ is still unclear.

Intestinal peptide YY: ontogeny of gene expression in rat bowel and trophic actions on rat and mouse bowel

The purpose of this study was twofold: 1) to characterize the profile of colonic peptide YY (PYY) gene expression in rats and 2) to examine for potential trophic effects of PYY on the intestine in rats and mice. Expression of PYY mRNA (analyzed by Northern blotting and in situ hybridization) and PYY (analyzed by high-performance liquid chromatography and radioimmunoassay) was detected initially at day 17 of gestation in colonic extracts of Sprague-Dawley and Fischer rats. Expression of colonic PYY mRNA increased until 7 days of age and remained at its highest level (approximately twofold greater than the adult level) through the end of the nursing period. After weaning (21 days of age), PYY mRNA levels declined quickly to adult levels. Colonic PYY concentrations followed, in a coordinated manner, with some temporal delay after birth, the increase and decrease of its mRNA. Administration of PYY increased the weight and DNA content of the duodenum significantly in nursing rats and adult mice. In mice, PYY treatment also increased weight and DNA content of the ileum and colon. The trophic effects of PYY were dose related, peptide specific, and independent of species and sex. From these findings, we hypothesize that PYY plays an important role in intestinal development and dietary adaptation.

Loss of heterozygosity in human primary prostate carcinomas: a possible tumor suppressor gene at 7q31.1

We studied loss of heterozygosity (LOH) on human chromosome 7q to determine the location of a putative tumor suppressor gene (TSG) in human primary prostate carcinomas. Samples were obtained from 16 primary prostate carcinomas surgically removed from patients at The University of Texas M. D. Anderson Cancer Center. Paired normal and tumor DNAs were used as template for PCR amplification of a set of 14 CA microsatellite repeats on 7q21-qter. Twelve of 16 cases studied had LOH at one or more loci on 7q. Eighty-three percent LOH (five of six informative cases) was detected with D7S522 at 7q31.1-7q31.2. Percentage of LOH was normally distributed around D7S522. The high incidence of LOH in primary prostate carcinomas suggests that there is a TSG relevant to the development of prostate cancers at 7q31.1-31.2, confirming our previous functional evidence for a TSG at this location. Further research needs to be conducted to establish the identity and function of this putative TSG.

Bombesin stimulates the in vitro growth of a human gastric cancer cell line

Bombesin (BBS) and its mammalian equivalent, gastrin-releasing peptide (GRP), exhibit diverse biological functions, including that of a neurotransmitter, a regulator of gastrointestinal hormone release, and a trophic factor for various normal and neoplastic tissues. Bombesin stimulates the growth of normal cells of the stomach, pancreas, and bronchial epithelium as well as cells in breast cancer, gastrinoma, and small cell lung cancer. The purpose of this study was to determine whether BBS regulates the growth of a human gastric cancer cell line (SIIA) in vitro, and if so, to examine the mechanisms of signal-transduction that are involved. We found that BBS stimulated the growth of SIIA cells in vitro. The GRP receptor antagonists, BIM 26189 and BIM 26226, had no effect on growth of SIIA cells. Although these antagonists blocked the BBS-induced increase of [Ca2+]i, they failed to block the growth-stimulatory effect of BBS. BBS stimulated intracellular tyrosine phosphorylation of multiple proteins, with a predominant protein of apparent molecular weight of 125 kDa. Inhibition of intracellular tyrosine kinases by tyrphostin blocked the growth-stimulatory effect of BBS on SIIA cells. These results indicate that BBS exerts its trophic effect on SIIA cells through a receptor(s) linked to tyrosine kinase pathway, but not to the phospholipase C (PLC) pathway.

Temporal-specific and spatial-specific patterns of neurotensin gene expression in the small bowel

Expression of the neurotensin/neuromedin N (NT/N) gene is developmentally regulated in a temporal- and spatial-specific pattern in the small bowel. The purpose of our study was to determine 1) whether the temporal expression of NT/N could be altered by ectopic placement of small bowel and 2) whether the spatial-specific expression of NT/N could be altered by different diets. We found that the relative temporal pattern of NT/N expression was unchanged in rat jejunal and ileal xenografts implanted into the flanks of athymic nude mice. To determine whether the spatial-specific pattern of NT/N expression could be altered by different luminal nutrients, 28-day-old rats were randomized to receive chow or chemically defined liquid diets for 60 days at which time the jejunoileum was divided into eight equal segments, and NT/N expression was analyzed. The normal pattern of increasing levels of NT/N mRNA along the jejunum-to-ileum axis was not altered by any of the liquid diets. In contrast to NT/N, we found that expression of sucrase-isomaltase varied greatly depending on both location and type of luminal nutrients. We conclude that the strict temporal- and spatial-specific pattern of NT/N expression is not affected by either location or luminal contents, thus suggesting an intrinsic program of NT/N gene expression. Furthermore, we speculate that the NT/N gene may provide a useful endocrine paradigm to investigate the factors regulating the establishment and maintenance of certain cell lineage-specific patterns along the cephalocaudal axis of the gut.

Expression of the neurotensin gene in fetal human liver and fibrolamellar carcinoma

OBJECTIVE

This study determined whether the neurotensin gene (NT/N) is expressed in the normal adult liver and focal nodular hyperplasia (FNH) and confirmed NT/N expression in fibrolamellar carcinoma; whether NT/N or the neurotensin receptor is expressed in the fetal liver; and whether hepatic resection leads to expression of NT/N.

SUMMARY BACKGROUND DATA

Neurotensin (NT), a gut tridecapeptide localized in the gastrointestinal tract of the adult to the small bowel, is an important hormone-regulating gut motility, secretion, and mucosal growth. Expression of the NT/N gene has been identified in fibrolamellar carcinomas, but NT/N is not known to be expressed in the normal liver.

METHODS

Sensitive ribonuclease (RNase) protection assays were used to determine whether NT/N is expressed in fibrolamellar carcinoma, FNH, or healthy fetal and adult livers. The authors also determined whether the receptor for NT was present in the fetal liver and whether liver resection and subsequent regeneration could lead to re-expression of NT/N in the rat.

RESULTS

Neurotensin is expressed in fibrolamellar carcinoma and in the fetal human liver, but not in the adult liver or the samples of FNH. In addition, the authors were not able to detect expression of the NT receptor in the fetal liver and did not identify NT/N gene activation in the regenerating liver of the rat.

CONCLUSIONS

The NT/N gene will be a useful molecular marker to differentiate fibrolamellar carcinoma from other liver tumors. The finding of NT/N expression in the fetal liver suggests a stem cell descendant that is common to both the liver and gut. The absence of NT/N expression in the regenerating liver suggests that NT does not play a role in this rapid growth process.

Bombesin improves survival from methotrexate-induced enterocolitis

OBJECTIVE

The authors determined whether bombesin could improve survival from methotrexate (MTX)-induced enterocolitis.

SUMMARY BACKGROUND DATA

Bombesin prevents gut mucosal atrophy, which is produced by feeding rats an elemental diet. Administration of MTX produces a lethal enterocolitis in rats fed an elemental diet.

METHODS

On treatment day 0, 60 rats were divided randomly into three groups and fed an elemental diet (Vivonex TEN, Sandoz, Minneapolis, MN) as the only source of nutrition. Groups were subdivided further to receive either saline or bombesin (10 micrograms/kg, subcutaneously, three times a day) beginning either on day 0 or day 14. Methotrexate (20 mg/kg, intraperitoneally) was given to all rats 14 days after the start of an elemental diet.

RESULTS

Bombesin prevented the mucosal atrophy in the ileum produced by the elemental diet and significantly decreased mortality in rats given MTX (whether given as a pretreatment or at the time of MTX administration).

CONCLUSION

Bombesin significantly improved survival in a lethal model of MTX-induced enterocolitis, possibly by maintaining gut mucosal structure. Administration of bombesin to patients receiving chemotherapy may be clinically useful in preventing the severe enterocolitis induced by various chemotherapeutic agents.

Bombesin inhibits growth of pancreatic ductal adenocarcinoma (H2T) in nude mice

Bombesin (BBS), a tetradecapeptide, stimulates growth of various types of cells, including fibroblasts and human small cell lung cancer, and has been termed the universal "on-switch" due to its ability to stimulate the release of numerous hormones. In addition, BBS receptors have been identified in normal and neoplastic pancreatic tissue. A pancreatic ductal adenocarcinoma cell line (H2T), established in our laboratory, possesses specific binding sites for BBS. The purpose of this study was to examine the effect of BBS on the growth of H2T tumors transplanted into athymic nude mice. H2T cells (5 x 10(6) cells/mouse) were injected s.c. into the interscapular region of the nude mice and then the mice were randomized into two groups (n = 10/group). Mice received either 0.1 ml of saline with 0.1% bovine serum albumin (BSA) (control) or 0.1 ml BBS (5 micrograms/kg) intraperitoneally, three times/day. Tumor area was measured twice weekly until the mice were killed (day 32), when tumor and normal pancreas were removed, weighted, and assayed for DNA and protein content. Administration of BBS significantly inhibited H2T tumor area, weight, and DNA and protein content. Conversely, growth of normal pancreas, removed as an in vivo bioassay so as to ensure the efficacy of BBS, was stimulated. We conclude that BBS is a growth inhibitory factor for H2T tumors and that different mechanisms may be responsible for the differential growth effects elicited by normal and neoplastic pancreas in response to BBS.

Lovastatin inhibits pancreatic cancer growth regardless of RAS mutation

Lovastatin, an inhibitor of the rate-limiting enzyme of cholesterol synthesis, inhibits growth of pancreatic cancer cells. A possible mechanism of this inhibition is that lovastatin inhibits the activity of RAS protein by depleting farnesyl (an intermediate of cholesterol synthesis). The K-ras gene is frequently mutated in pancreatic cancers and RAS protein requires farnesyl to be bound to the cell membrane and thereby activated. To investigate whether lovastatin inhibition of cell growth depends upon the presence of ras mutation, codons 12/13 and 61 of ras genes were examined by the dideoxynucleotide chain-terminating method in five pancreatic cell lines (human CAPAN2, CAV, MIA Paca2, PANCi, and hamster H2T) on which lovastatin exerted a growth-inhibitory effect. These codons play a major role in tumorigenic mutation of ras genes. Lovastatin inhibited cell growth by 99% (MIA), 97% (H2T), 78% (CAV), 41% (CAPAN2), and 23% (PANC1), respectively, when cells were treated with 2.5 micrograms/ml lovastatin for 6 days. Activating point mutations were found in codon 12 of the K-ras gene (wild type:GGT) in MIA (GTT), H2T (GAT), CAPAN2 (TGT), and PANC1 (GAT) but not in CAV. In addition, the CAV cell line did not have a mutation in either H- or N-ras genes. Lovastatin inhibited the growth of CAV cells even though this cell line did not have ras mutation, suggesting that lovastatin inhibition of pancreatic cancer cell growth is not directly dependent on the presence of ras mutation.

Growth-regulatory effect of gastrin on human colon cancer cell lines is determined by protein kinase a isoform content

Cell growth is regulated by various peptide growth factors through receptor-linked multiple intracellular signal-transduction pathways, such as the cyclic adenosine monophosphate (cAMP) pathway. cAMP activates cAMP-dependent protein kinase A (PKA) either to stimulate or inhibit cell growth. The effect on growth is determined by the presence of two isoforms of the regulatory (R) subunit of PKA; activation of RI alpha-type PKA leads to stimulation of growth, activation of RII beta-type inhibits cell growth. We determined whether the effect of gastrin on the growth of human colon cancer cells is determined by cell-specific content of PKA. We utilized two human colon cancer cell lines: LoVo, growth of which is stimulated by gastrin, and HCT116, growth of which is inhibited by gastrin. Activation of both types of PKA with 8-Br-cAMP mimicked the regulation of growth by gastrin; preferential activation of RII beta-type PKA with 8-Cl-cAMP inhibited growth of both cell lines. LoVo cells possess the predominantly RI alpha isoform of PKA at the mRNA and protein level; HCT116 cells possess predominantly the RII beta-type PKA. The cAMP-mediated regulation of growth (either stimulatory or inhibitory) by gastrin on these human colon cancer cells was determined by the predominant isoform of PKA.

Gastrin stimulates growth of human colon cancer cells via a receptor other than CCK-A or CCK-B

Two receptors for cholecystokinin (CCK) have been isolated which also bind gastrin: CCK-A type and CCK-B type, both are coupled to phospholipase C (PLC) activation. However, identification of the "true" gastrin receptor remains controversial. We determined which CCK receptor mediated the trophic effect of gastrin on human colon cancer cells (LoVo). LoVo cells lack mRNA for either CCK receptor by Northern hybridization. Gastrin stimulated cyclic AMP production, not PLC activity, in LoVo cells. The trophic effect was not blocked by receptor antagonists for CCK-A (L364,718) or CCK-B (L365,260). The gastrin receptor pharmacology on LoVo cells and the lack of appropriate transcripts suggest that gastrin stimulated growth of these cells by a receptor other than CCK-A or CCK-B type and there likely exists another receptor for gastrin.

Experimental gene therapy of human colon cancer

BACKGROUND

Gastrin regulates growth of human colon cancer cells by activation of the cyclic adenosine monophosphate (cAMP)-dependent protein kinase A (PKA). Gastrin and 8-Br-cAMP, a membrane-permeable cAMP analog, inhibit growth of HCT116 cells; both stimulate growth of LoVo cells. This dual effect on growth may be explained by relative amounts of the regulatory subunit (RI alpha or RII beta) of PKA within the cancer cells. Antisense oligodeoxynucleotides (ASO) to either RI alpha or RII beta inhibit protein translation of the target mRNA by sequence-specific binding; subsequently, cellular PKA content and the cAMP-mediated growth may be altered. We determined whether ASO to either the RI alpha or RII beta subunit altered the cAMP-mediated growth of HCT116 and LoVo human colon cancer cells.

METHODS

HCT116 cells were treated with RII beta ASO (15 mumol/L, 4 days) and then treated with 8-Br-cAMP (25 mumol/L); tritiated thymidine incorporation was measured after 24 hours, and the cell number was determined on alternate days. Protein and mRNA levels of the RII beta subunit were determined by Western and Northern blotting, respectively. Similar studies with an ASO against the RI alpha subunit were performed on LoVo cells.

RESULTS

RII beta ASO reversed the cAMP-mediated inhibition of growth of HCT116 cells, and RII beta ASO decreased the protein level of the RII beta subunit. RII beta ASO did not alter the basal growth of HCT116 cells. RI alpha ASO reversed the cAMP-mediated stimulation of growth of LoVo cells.

CONCLUSIONS

The regulatory subunits of PKA are potential targets to alter growth of human colon cancer cells. Gene therapy directed to alter specific steps in signal transduction pathways may provide new therapeutic strategies.

Activation of hepatic proliferation-associated transcription factors by lipopolysaccharide

BACKGROUND

The hepatic acute-phase response is the result of reprogramming of gene expression in the liver. Similar acute-phase responses occur in regenerating liver after partial hepatectomy and are preceded by increases in the expression of a set of transcriptional regulatory proteins that are encoded by "immediate-early" genes. The purpose of this study was to determine whether acute systemic inflammation after lipopolysaccharide injection induces hepatic immediate-early genes that are induced by partial hepatectomy.

METHODS

Two- to 4-month-old Balb/c mice received intraperitoneal Escherichia coli lipopolysaccharide (0111:B4; 100 micrograms), and total liver RNA, nuclear protein extracts, or total liver protein lysates were obtained at 0, 1, 3, 12, and 24 hours. RNA blot hybridization analysis was used to determine steady-state messenger RNA levels for c-jun, jun-B, jun-D, c-fos, fos-B, fra-1, nup475, and zif268. Specific nuclear protein-binding activity was determined by gel mobility shift assay. The protein c-Jun was detected by antibody-blocking experiments, and Jun-B was detected by gel supershift assay of the activating protein (AP-1) complex. Steady-state Jun-B levels were determined by immunoblot analysis.

RESULTS

Intraperitoneal injection of lipopolysaccharide is followed by induction (from fivefold to 13-fold) of c-jun, jun-B, c-fos, zif268, and nup475 messenger RNAs in the liver. Lipopolysaccharide induced increases in AP-1 and Zif268 consensus DNA-binding activity in mouse liver. The proteins c-Jun and Jun-B are detected in the AP-1 complex after administration of lipopolysaccharide.

CONCLUSIONS

The induction of hepatic immediate-early genes after lipopolysaccharide is similar to that that follows partial hepatectomy. These transcription factors likely have important roles in the reprogramming of gene expression that leads to the acute-phase response.

Effect of aging on neurotensin-stimulated growth of rat small intestine

The proliferative activity of gut mucosa is altered with aging; the potential for the aged gut to respond to trophic stimuli is not known. The purpose of this study was to determine whether there are age-related differences in the effects of the trophic gut peptide neurotensin (NT) on the structure and function of small bowel mucosa. NT (300 micrograms/kg) or saline (control) was injected subcutaneously at 8-h intervals for 5 days in rats of two age groups, young (2 mo) and aged (24 mo). On day 6, rats were killed, and the gut mucosa (proximal and distal small bowel) was scraped, weighed, and analyzed for DNA, RNA, and protein content and for disaccharidase (sucrase and maltase) activity. In a second experiment, the groups of rats and the protocol for NT administration were identical; however, when the rats were killed, the distal gut was removed for histological evaluation of crypt and villus length (mm) and density (no./cm gut segment) and bromodeoxyuridine immunohistochemistry. NT produced significant increases in mucosal growth (wt, DNA, RNA, and protein) in both age groups when compared with age-matched controls; the increase of growth measurements was the greatest in the small bowel mucosa of the aged rats. In addition, NT increased crypt density in both groups; only the aged group treated with NT demonstrated increases in crypt depth and villus height. Specific activities of sucrase and maltase did not change with NT treatment in either of the age groups. We conclude that the proliferative potential of small bowel mucosa is maintained with aging in response to administration of NT.(ABSTRACT TRUNCATED AT 250 WORDS)

Cytocidal effect of high energy shock wave on tumour cells enhanced with larger dose and multiple exposures

Cultured LLC-WRC256 (Walker rat carcinoma) cells were exposed to different doses of high energy shock waves (HESW). The immediate viabilities were 98% in the control cells, and 74%, 53% and 18% following 400, 800, and 1500 HESW treatment, respectively. Surviving cells in the 400 and 800-treated HESW demonstrated delayed upward growth rate curves, and the 1500 HESW-treated a downward curve. Agar clonogenic efficiencies for surviving cells were 36% (control), 20% (400 HESW), 15% (800 HESW) and 3% (1500 HESW). LLC-WRC256 tumours in Wistar rats were treated once every other day with 1500 HESW on a total of three occasions. Tumours treated with HESW grew more slowly (4.9 cm3) than those in the control (13.5 cm3). HESW fragmented cells and destroyed cell membranes and intracellular organelles. A histological examination of tumours treated with HESW demonstrated local haemorrhage with necrosis in the HESW focus area. Damage to the surrounding skin and soft tissue was slight and transient. These findings suggest that the growth of tumour cells can be suppressed in vitro and in vivo by treatment with HESW.

Gastrinomas demonstrate amplification of the HER-2/neu proto-oncogene

OBJECTIVE

This study determined whether genomic amplification of HER-2/neu or mutations of the p53 and ras genes were present in gastrinomas.

SUMMARY BACKGROUND DATA

Amplification of HER-2/neu, a proto-oncogene related to the epidermal growth factor receptor, and mutation of the ras proto-oncogene and p53 tumor suppressor gene appear to play a role in the pathogenesis of some human cancers. Little is known about possible molecular alterations in gastrinomas, tumors that may be particularly virulent because of gastrin overproduction, resulting in the severe ulcer diathesis, the Zollinger-Ellison syndrome.

METHODS

The differential polymerase chain reaction (PCR) procedure was used to detect amplification of the HER-2/neu gene in DNA samples from the novel human gastrinoma cell line (PT) and from paraffin-embedded samples of gastrinomas. Sequencing techniques were used to determine whether mutations of the p53 or ras (Ha-ras, N-ras, Ki-ras) genes were present.

RESULTS

Amplification (> twofold) occurred in all gastrinoma tumor samples. Compared with normal pancreas or ileum, a 4- to 12-fold amplification of HER-2/neu was found in 3 gastrinomas, 3 to 3.3-fold in four samples and 2.1- to 2.4-fold in the remaining five tumors. A heterozygous point mutation in the p53 gene (codon 273) was found in a single sample; none of the gastrinomas contained a mutation of the ras genes.

CONCLUSIONS

Amplification of the HER-2/neu gene, but not alterations of either p53 or ras, may be involved in the pathogenesis of gastrinomas. The unique PT cell line will be a useful model to further elucidate the molecular mechanisms that contribute to gastrinoma formation and growth.

Effects of gastrin on 3',5'-cyclic adenosine monophosphate, intracellular calcium, and phosphatidylinositol hydrolysis in human colon cancer cells

Gastrin is a trophic factor for some human colon cancer cells. However, the signal-transduction pathways by which gastrin regulates growth are still unknown. We examined the effect of synthetic human gastrin-17 (G-17) on signal-transduction pathways and cell growth using 4 different human colon cancer cell lines (LoVo, COLO 320, HT-29, and HCT116). G-17 stimulated the production of cyclic AMP in LoVo, COLO 320, and HCT116 cells, while G-17 stimulated phosphatidylinositol hydrolysis and mobilization of intracellular calcium in HT-29 cells. The growth-regulatory effect of G-17 on these colon cancer cells (stimulatory on LoVo, COLO 320, and HT-29 cells; inhibitory on HCT116 cells) was well correlated with the effect of G-17 on the signal-transduction pathway in each cell line. We further examined the effect of a selective cholecystokinin-B type receptor antagonist, JMV 320, on G-17-induced signal-transduction pathways and G-17-regulated growth. In each cell line, the effect of JMV 320 on G-17-induced signal-transduction pathways was well correlated with that on G-17-regulated growth. G-17 appears to regulate, at least to some extent, growth of human colon cancer cells through gastrin receptor-linked signal-transduction pathways that are cell-specific.

Mentoring: a professional commitment

Nursing professionals have an obligation to increase the number and quality of nurses of color in the profession. Nursing students of color are often at risk of dropping out of the nursing program. Leaders of the National Black Nurses Association recognize the value of mentoring to improve student retention. Mentors help others reach their life goals by offering their proteges support, nurturing, and professional contacts. Non-traditional students over the age of 25 and students of color especially need the benefits of a mentor to help overcome inherent prejudicial assumptions in the educational system. The Board of Regents of the University of the State of New York recommended support systems to improve retention of students of color. The Queens County Black Nurses Association developed a pilot mentor project in 1991, establishing ten mentor-protege relationships. In 1992, five more relationships were added. Of the initial group, two proteges graduated and completed the NCLEX-RN exam. One student left for failure to meet academic requirements. The remaining seven are making progress, but more programs are needed. Professional nurses who have achieved success are reaching out to assist others whose potential has yet to be tapped. The QCBNA's project goes on, guaranteeing a continuous body of well-trained nurses of color to meet the health care needs of a growing, underserved population.

Differential diagnosis of tumour-associated hypoglycaemia in small animals

Abstract While there are a number of causes of hypoglycaemia in small animals, many of these may be ruled out on the basis of clinical signs, history, age and other laboratory results. Further tests for diagnosis include insulin measurements, the glucagon tolerance test and glucose administration tests. For the diagnosis of insulinomas (β cell tumours) in dogs, serum insulin and glucose concentrations may be measured at the same time and put into the amended insulin to glucose ratio (AIGR), which is reportedly the most accurate method of diagnosis. The ratio provides an indication of whether or not the serum concentration of insulin is appropriate for the concentration of glucose. The value of this ratio in cats is not known because there are so few reports of insulinomas in this species. In cats it may be better to simply compare insulin and glucose levels to see if they are appropriate. The occasional false-positive AIGR has been reported in dogs with other tumours and severe sepsis, but with these conditions the insulin is usually also low. Insulin to glucose and glucose to insulin ratios may also be calculated but are considered less useful than the AIGR. The glucagon tolerance test is considered less accurate than the AIGR but may be used instead of, or in addition to, the AIGR if results of the AIGR are equivocal.

Inhibitory effect of calcium channel blockers on growth of pancreatic cancer cells

Calcium, which binds to calmodulin inside the cells, is an important mediator of various intracellular processes, including cell proliferation. We speculated that blockade of Ca2+ influx into the cells by Ca(2+)-channel blockers, such as phenytoin and verapamil, might affect the Ca(2+)-calmodulin pathway leading to suppression of cell growth. In this study, we examined the effect of phenytoin and verapamil on growth of two human pancreatic cancer cell lines, MIA PaCa-2 and CAV, in vitro and in vivo. Both phenytoin and verapamil inhibited growth of the two cell lines in a dose-dependent fashion. Phenytoin and verapamil each significantly prolonged doubling time of MIA PaCa-2 and the combination of the two drugs acted synergistically. The activity of ornithine decarboxylase, which is a rate-limiting enzyme of the polyamine pathway that is closely related to cell proliferation, was significantly inhibited by both drugs in a time-dependent fashion. Phenytoin, but not verapamil, inhibited growth of MIA PaCa-2 tumors xenotransplanted into nude mice, whereas both phenytoin and verapamil inhibited the growth of CAV tumors. Since phenytoin and verapamil are known to have fewer side effects than conventional antineoplastic drugs, these results suggest their possible use in novel therapeutic strategies.

In vitro relationship between magnesium and insulin secretion

Magnesium, the most abundant intracellular divalent cation, is known to play an essential role in many normal cell functions, such as fluid and electrolyte transport, enzyme activity, and cell proliferation. It is known that magnesium deficiency or hypomagnesaemia induces hyperinsulinism, while hypermagnesaemia inhibits insulin secretion: however, the mechanism controlling the intracellular level of free magnesium and its role in the insulin-secretory mechanism of pancreatic beta cells (RIN m5F cells) are still unclear. Using a fluorescent indicator (mag-fura-2) we have found that the influx of magnesium appears to be voltage-dependent and is sensitive to blockade of the voltage-dependent calcium channel in RIN m5F cells; the efflux of magnesium appears to be voltage- and cyclic AMP-independent. We have observed that depletion of extracellular magnesium potentiates insulin secretion from RIN m5F cells. This finding has led us to speculate on two possible mechanisms through which extracellular magnesium participates in the regulation of insulin secretion: (1) extracellular magnesium may regulate ATP-sensitive potassium channels, and (2) extracellular magnesium may act as a competitive inhibitor of the calcium influx mediated through the voltage-dependent calcium channel. In addition to the role of extracellular magnesium, the changes in the intracellular levels of free magnesium observed during secretagogue-stimulated insulin secretion may alter magnesium-sensitive enzymes or systems, which may play regulatory roles in signal transduction. Elucidation of the role of magnesium in the insulin secretory mechanism will be beneficial for understanding the insulin secretory mechanism of pancreatic beta cells and may be helpful in treating insulin-related abnormalities in patients with hypo- or hypermagnesaemia.

Organ physiology of aging

With improvements in medical care over the last several decades, individuals are living longer and, as a result, more surgical procedures will be performed in the geriatric patient. Normal physiologic aging is characterized by a gradual loss of reserve capacity. The effects of the aging process on various organ systems do not usually affect function in the normal state; however, during periods of stress (such as with a surgical procedure or illness), the elderly patient may not be able to meet the increased metabolic demand. This loss of reserve capacity is the single most important factor that decreases the elderly patient's ability to tolerate operations. It is imperative that the surgeon identify the elderly patient who is at increased risk for complications. Specific consideration must be given to proper management of fluid and electrolyte replacement, respiratory management to prevent atelectasis and pneumonia, and monitoring for possible cardiac complications.

Transforming growth factor-beta inhibits rat intestinal cell growth by regulating cell cycle specific gene expression

Transforming growth factor-beta 1 (TGF-beta 1) inhibits the growth of intestinal cells, but the mechanisms involved are unknown. Using a rat intestinal crypt cell line (IEC-6), we determined the site of action in the cell cycle that TGF-beta 1 acts to suppress proliferation. We also examined the effect of TGF-beta 1 on the expression of proliferation-associated "immediate early" genes (zif268, jun-B, c-myc) during the early G1 phase and the cdc2 gene during the transition from the G1 phase to the S phase of the cell cycle. Cell cycle progression was determined by incorporation of 3H-thymidine, and gene expression was analyzed by Northern blot analysis. We found that TGF-beta 1 acts to inhibit proliferation of rat intestinal crypt cells by blocking cell cycle progression at the middle G1 phase. The genes activated during G1 can be divided into TGF-beta 1 insensitive (zif268, jun-B, and c-myc) and TGF-beta 1 sensitive (the cdc2 gene). TGF-beta 1 suppresses the induction of the cdc2 gene during the G1/S transition without inhibiting the activation of immediate early genes during the early G1 phase.

Characterization of a human pancreatic carcinoid in vitro: morphology, amine and peptide storage, and secretion

The study of functioning human endocrine tumors has been hampered by a lack of suitable in vitro models. We have established the first permanent cell line of a human pancreatic carcinoid tumor (BON) in culture. BON cells grow in monolayer culture and form colonies in soft agar. Injection of BON cells into nude mice produces transplantable tumors in a dose-dependent fashion. The histology of tumors in athymic mice from injection of dispersed, cultured BON cells is similar to the original histology of the resected tumor. Significant amounts of neurotensin, pancreastatin, and serotonin (5-HT) are demonstrated in the cells by radioimmunoassay (RIA) and the presence of chromogranin A, bombesin, and 5-HT is confirmed by immunocytochemistry. Numerous round and pleomorphic dense-core neurosecretory granules are present on electron microscopy. Functional receptors for acetylcholine, 5-HT, isoproterenol, and somatostatin are present on cultured cells. BON cells possess a specific transport system for uptake of 5-HT from the medium; this uptake system may be a route for regulation of autocrine effects of 5-HT on carcinoid cells. This unique human carcinoid tumor cell line should provide the opportunity for new insight into the biology of carcinoid tumors and of specific intracellular mechanisms for secretagogue action in the release of amines and peptides.

Effects of FK506 and cyclosporine on dynamic insulin secretion from isolated dog pancreatic islets

Pancreatic islet transplantation may be the most ideal treatment for patients with insulin-dependent diabetes mellitus. However, immunosuppressive agents such as cyclosporine A(CsA) and FK506, used for these transplanted patients have been reported to cause glucose intolerance. In the present study, we have compared the effects of CsA and FK506 on glucose-stimulated insulin release from the isolated dog pancreatic islets, which have been maintained in culture for 3 days after isolation. The isolated dog pancreatic islets, pretreated for 24 hr with either CsA or FK506 (1, 10, and 100 nM), were perifused with 16.7 mM glucose. Pretreatment with both drugs suppressed glucose-stimulated insulin secretion in a dose-dependent fashion. CsA (100 nM), which is a therapeutically relevant concentration, significantly suppressed both the first and second phases of glucose-stimulated insulin release compared with 100 nM FK506. These findings suggest that, with a therapeutically relevant concentration, FK506 may be less toxic than CsA against pancreatic islets in patients with organ or cell transplantation.

The effect of endogenous cholecystokinin released by bombesin and trypsin inhibitor on the regeneration of the pancreas

OBJECTIVE

This study examined the effects of endogenous cholecystokinin (CCK) released by bombesin and FOY-305 (a synthetic inhibitor of trypsin on pancreatic regeneration in rats).

SUMMARY BACKGROUND DATA

Trophic gut hormones (CCK and bombesin) stimulate the growth of the normal rat pancreas. However, the influence of endogenous gut hormones on pancreatic regeneration is unclear.

METHODS

Male Fisher rats (n = 6 to 8 per group) were fed a protein-free diet and given ethionine (700 mg/kg intraperitoneally daily) for 8 to 9 days to induce degeneration of the pancreas. Regeneration was stimulated by giving the rats a regular chow diet. The effects of bombesin (10 micrograms/kg three times a day for 7 days) or FOY-305 (200 mg/kg daily for 8 days) on the process of regeneration were examined.

RESULTS

At the end of the degeneration phase, there was near-total destruction of pancreatic acinar cells. Both bombesin and FOY-305 stimulated pancreatic regeneration. Growth measurements (weight and total content of DNA and protein) were significantly increased (p < 0.05) in the bombesin- and FOY-305-treated rats compared with controls. Histologic examination revealed widespread repopulation of the pancreas with acinar cells in the bombesin- and FOY-305-treated groups. The stimulating effects of both bombesin and FOY-305 on pancreatic regeneration were blocked completely by the CCK-receptor antagonist L-364,718. Growth measurements were not significantly increased in the groups of control rats or rats given L-364,718 alone.

CONCLUSIONS

These results show that bombesin and FOY-305 significantly stimulated pancreatic regeneration. Because the stimulating effects of bombesin and FOY-305 on regeneration were blocked by the specific CCK-receptor antagonist L-364,718, it was concluded that this effect was mediated by endogenous CCK.

Neural regulation of peptide YY secretion

The purpose of these experiments was to investigate the neural control of peptide YY (PYY) secretion. The effects of various pharmacological manipulations and vagotomy on peptide YY (PYY) secretion was examined in dogs. Atropine, hexamethonium and atropine plus hexamethonium treatment blocked food-induced release of PYY significantly. Integrated release of PYY in response to food alone and in combination with atropine, hexamethonium and atropine plus hexamethonium were 8.8 +/- 2.2, -1.1 +/- 2.3, -2.7 +/- 2.2 and -3.2 +/- 3.1 (ng (0-150) min/ml), respectively. beta-Adrenergic blockade with propranolol or depletion of nerve terminal stores of catecholamines with reserpine did not affect food-stimulated release of PYY. Truncal vagotomy resulted in significant elevations of basal and food-induced release of PYY. IV administration of bethanechol, a cholinergic agonist, and electrical stimulation of the vagus nerve resulted in release of PYY. Together, these data suggest that food-stimulated PYY secretion is dependent on ganglionic transmission and an atropine-blockable postganglionic parasympathetic pathway; and that PYY release is inhibited tonically, probably through a vagal cholinergic mechanism. Adrenergic pathways do not participate in food-stimulated PYY release; however, electrical stimulation of the splanchnic nerves increased basal levels of PYY, suggesting that the sympathetic nervous system affects release of PYY.

Biomolecular advances in gastrointestinal hormones

Gastrointestinal hormones are chemical messengers that regulate a broad range of physiologic functions. Although primarily expressed within tissues of the gut, these peptide hormones are widely distributed throughout the body and act on multiple target tissues. Furthermore, these regulatory peptides can exist in multiple molecular forms that may bind to multiple cell-surface receptors coupled to one of several possible signal transduction systems leading to diverse biologic responses. With such an expansive field to study, it is not surprising that gut endocrinologists have embraced the new techniques that are emerging from the revolution of molecular biology. Beginning with the first construction of a recombinant DNA molecule by Paul Berg in 1971, molecular biology has developed many new techniques that have been rapidly adopted by gut endocrinologists to enable a more detailed understanding of gastrointestinal function. The merging of these two fields has led to a new area of research, molecular gut endocrinology, or the study of gut physiology and endocrinology at the level of individual molecules (ranging from polypeptide-surface receptors to small-molecule second messengers to DNA sequences). Gut cells are constantly bombarded by numerous hormones, and the tightly regulated physiologic status of each cell is becoming more clearly understood.

Age-related changes in polyamine biosynthesis after fasting and refeeding

The effect of aging on ornithine decarboxylase (ODC) activity and polyamine biosynthesis in the proximal small intestine was studied in two groups of male Fisher 344 rats (young [4-month old] and aged [26- to 27-month old]) using a fasting and refeeding model. In control (nonfasted) rats, levels of polyamines (putrescine, spermidine and spermine) and ODC activity were significantly higher in aged compared with young rats. In aged rats, fasting significantly reduced the levels of putrescine by 41%, spermidine by 23%, and spermine by 11%; however, fasting had no effect on polyamine levels in young rats. ODC activity was decreased 75% in young and 50% in aged rats after fasting compared with the respective age-matched controls. Conversely, 2 h after reinstituting a chow diet increased ODC activity by 17-fold in young rats but only 8-fold in aged rats. Putrescine levels were also increased in both age groups after refeeding; however, similar to ODC activity, these increases were much less in aged rats. In addition, spermidine and spermine levels remained significantly depressed in the aged groups even after 24 h of refeeding. These findings suggest that the normal rigid control of gut polyamine biosynthesis and proliferation noted in young rats is markedly altered with aging.

Comparative effects of neurotensin and neuromedin N on growth of human pancreatic cancer, MIA PaCa-2

Neurotensin (NT), an important regulatory hormone of the gut, stimulates growth of the human pancreatic cancer cell line MIA PaCa-2 in vitro. The purpose of our study was to compare the stimulatory effects of NT and neuromedin N (NMN), a structurally related hexapeptide, on the growth of MIA PaCa-2. In addition, the effects of NT on the growth of MIA PaCa-2 xenografts and normal GI tissues were assessed in athymic nude mice. MIA PaCa-2 cells, plated in serum-free media, were treated with either NT (10(-12)-10(-6) M) or NMN (10(-11)-10(-7) M) and cells were counted. For the in vivo study, MIA PaCa-2 cells were inoculated sc into 30 athymic nude mice and then randomized to two groups to receive either NT (600 micrograms kg-1, sc, tid) or vehicle. At sacrifice (day 35), the xenografted tumours, as well as normal host pancreas, jejunum and ileum were removed, weighed, and assayed for DNA, RNA and protein. Both NT and NMN stimulated the growth of MIA PaCa-2 cells in vitro with maximal (approximately 30%) increases occurring with dosages of 10(-9) M. In vivo, NT had a transient effect on xenografted MIA PaCa-2 tumour area with increases noted on days 21 and 25 of the study. Conversely, NT significantly stimulated the growth of jejunum and ileum, with a more pronounced effect noted in the jejunum. NT and NMN have similar growth-stimulatory effects on MIA PaCa-2 cells in vitro, which suggests an interaction through the same receptor.(ABSTRACT TRUNCATED AT 250 WORDS)

New experimental model of proximal and distal colon transposition in rats

The proximal and distal portions of the colon have different morphologic and histochemical features. To ascertain whether these features are genetically or environmentally determined, we attempted to develop a transposition model of the proximal and distal portions of the colon in rats. Four-month-old male Fisher 344 rats were used. Four centimeters of the proximal colon segment circulated by the right colonic artery and 4 cm of the distal colon segment circulated by the middle colic artery were interchanged isoperistaltically. In the control group, the colon was transected and reanastomosed. All rats tolerated the surgery and maintained good condition for 4 weeks, when they were euthanized. No differences in body weight and food intake were observed between the transposition and control groups. Macroscopic appearance of the stomach and small intestine was normal in both the transposition and control groups, but the cecum was dilated and the new proximal portion of the colon was slightly dilated in the transposition group. This new experimental model will be helpful in examining the mechanism by which different features of the proximal and distal portions of the colon are derived. It will also assist in the research of carcinogenesis in the colon, in determining why the distal portion of the colon is more susceptible to carcinogens, compared with the proximal portion of the colon.

Differential expression of the neurotensin gene in the developing rat and human gastrointestinal tract

Neurotensin (NT) is an important hormone regulating gut motility, secretion, and growth. The purpose of this study was to determine the developmental expression of the NT/neuromedin N gene (NT/N) in the gut and pancreas of rats and humans. We found that NT/N expression, initially low in the fetal rat jejunum and ileum, is increased by postnatal day 3. This increase is independent of contact with luminal nutrients as demonstrated by elevated NT/N expression in rat jejunoileal grafts implanted in nude mice. NT/N expression reaches maximal levels in the small bowel by postnatal day 14. After postnatal day 28, NT/N mRNA levels remain constant in the ileum but decrease in the jejunum. Transient NT/N expression is found in the colon of fetal and postnatal rats. Similar to the rat, NT/N expression is low in the human fetal ileum but increases in the adult. In the human colon, NT/N is transiently expressed in the fetus at midgestation but disappears by birth and, similarly, is not apparent in the adult. We conclude the following. 1) The NT/N gene demonstrates a complex pattern of tissue-specific expression; the jejunum and ileum show a similar pattern of expression until the end of the fourth postnatal week, when NT/N levels decrease in the jejunum to assume the distinctive adult topographical distribution with NT/N increasing along the jejunoileal axis. 2) NT/N is transiently expressed in the colon of rats and humans during a developmental stage characterized by morphological and functional similarities to the small bowel; therefore, NT/N may provide a useful endocrine marker to further define the complex differentiation pathway leading to small bowel and colonic phenotypes.

Effect of 5-HT3 receptor antagonist (ondansetron) on functioning human pancreatic carcinoid cells

5-Hydroxytryptamine (5-HT) is a mitogen for selected cell types. We have reported that 5-HT is an autocrine growth factor for functioning human pancreatic carcinoid (BON) cells; autocrine growth effect is transmitted by 5-HT1A but not 5-HT1C/2 receptors, activation of which decreases cyclic AMP production through a pertussis toxin-sensitive inhibitory GTP-binding protein. In this study, the effect of 5-HT3 receptor antagonist, ondansetron, on BON was examined. Ondansetron did not affect growth of BON cells and also affected neither stimulation of phosphatidylinositol hydrolysis or inhibition of cyclic AMP production evoked by 5-HT in BON cells. Ondansetron, however, inhibited mobilization of intracellular calcium evoked by 5-HT. Present findings suggest that BON cells possess 5-HT3 receptors, but their roles in pancreatic carcinoid cells are still unknown.

Developmental expression of the neurotensin gene in the rat liver

OBJECTIVE

This study determined whether the neurotensin gene is expressed during early development of the liver.

SUMMARY BACKGROUND DATA

Neurotensin (NT), a gut tridecapeptide localized mainly to the distal small bowel and brain of adults, is an important hormone regulating gut motility, secretion and mucosal growth. Expression of NT peptide and the gene is found in fibrolamellar hepatocarcinomas, a variant of hepatocellular carcinoma, but not in the normal adult liver.

METHODS

Northern and in situ hybridization techniques were used to determine expression of the neurotensin gene (NT/N) in the normal developing liver.

RESULTS

NT/N is expressed in the fetal and early postnatal rat liver, but expression is repressed in the liver of the adult. In situ hybridization confirms the authors' Northern data and demonstrates a random distribution of NT/N expression in the fetal and 3-day postnatal liver.

CONCLUSIONS

The authors conclude from this study that NT/N is expressed during early development of the rat liver with subsequent repression in the adult. NT/N may be reexpressed with malignant transformation of the liver.

Glutamine is essential for epidermal growth factor-stimulated intestinal cell proliferation

BACKGROUND

Glutamine stimulates growth of intestinal mucosa in vivo, but the mechanisms involved are unknown. The purpose of this study was to determine whether glutamine is essential for proliferation of enterocytes stimulated by epidermal growth factor (EGF). In addition, we determined which specific mitogenic actions of EGF require glutamine.

METHODS

A nontransformed rat intestinal mucosal cell line (IEC-6) was stimulated with EGF (20 ng/ml) without and with glutamine (0.1 to 10 mmol/L). DNA, RNA, and protein synthesis were quantitated by determining incorporation of tritiated thymidine, tritiated uridine, and 14C-leucine, respectively. Cell numbers and messenger RNA levels of early growth response genes (zif268, jun-B, c-myc) were also determined.

RESULTS

Glutamine was required for EGF stimulation of DNA, RNA, and protein synthesis and cell replication; however, EGF-stimulated expression of zif268, jun-B, and c-myc occurred in the absence of glutamine.

CONCLUSIONS

This study showed that glutamine is essential for EGF-stimulated intestinal mucosal cell proliferation. The mitogenic effects of EGF can be divided into the glutamine-independent, such as the signal transduction pathway leading to the induction of early growth response genes, and the glutamine-dependent, including DNA, RNA, and protein synthesis.

Novel action of transforming growth factor beta 1 in functioning human pancreatic carcinoid cells

We have shown recently that 5-HT is an autocrine growth stimulatory factor for a cell line (BON) that is derived from a human pancreatic carcinoid tumor. This action is mediated by a 5-HT receptor-linked decrease of cyclic adenosine monophosphate (AMP) production, but not mediated by a 5-HT receptor-linked stimulation of phosphatidylinositol hydrolysis. The BON cells also express transforming growth factor betas (TGF beta s) (1, 2, and 3) and release TGF beta into their medium. In this study, we examined the effects of TGF beta on the secretion of 5-HT, on signal transduction pathways involved in 5-HT secretion, and on growth of BON cells. TGF beta 1 inhibited basal and acetylcholine-stimulated release of 5-HT, but did not inhibit isobutylmethylxanthine-stimulated release of 5-HT. TGF beta 1 inhibited both basal and acetylcholine-stimulated hydrolysis of phosphatidylinositol in a dose dependent manner, but did not affect cyclic AMP production. TGF-beta 1 inhibited growth of BON cells in culture; this effect was reversed by exogenously administered 5-HT. Three different specific and saturable TGF beta 1 binding sites were identified; binding assays performed after mild acid wash (0.1% acetic acid, pH 2.5) conditions uncovered TGF beta receptors that were apparently occupied by endogenously produced TGF beta species. Affinity cross-linking assay showed that BON cells had three different TGF beta binding proteins. These results suggest that TGF beta 1 can inhibit growth of BON cells by altering secretory responses of 5-HT by means of receptor-mediated inhibition of phosphatidylinositol hydrolysis. We conclude that growth of BON cells is regulated, at least in part, by the opposing receptor-mediated autocrine actions of 5-HT and TGF beta.

Accidental poisoning of a group of yearling cattle by the organophosphate insecticide trichloronat

Eight yearling cattle were accidentally poisoned with the agricultural organophosphate insecticide trichloronat. One animal showed signs of acute organophosphate poisoning and died. The others showed signs of chronic organophosphate poisoning (organophosphate-induced delayed neuropathy) after 2-3 weeks and one animal died from renal failure at 12 weeks. High levels of trichloronat were measured in fat samples at 6 1/2 weeks. The remaining animals still showed signs of ataxia, possibly due to distal axonopathy, 1 year later but no trichloronat was detected in fat samples at this time.

Pituitary adenylate cyclase activating polypeptide stimulates release of peptide YY

The purpose of these experiments was to examine the effects of the recently discovered gastrointestinal peptide, pituitary adenylate cyclase activating polypeptide (PACAP), and two structurally related peptides, vasoactive intestinal polypeptide and secretin, on release of peptide YY (PYY) in conscious dogs. Intravenous administration of PACAP-27 or -38 stimulated a dose-related release of PYY; PACAP-27 was more potent than PACAP-38. PACAP-stimulated release of PYY was inhibited significantly by atropine, whereas ganglionic or beta-adrenergic blockade with hexamethonium and propranolol treatment, respectively, did not affect PACAP-induced release of PYY significantly (P > 0.05). These results indicate that PACAP-induced release of PYY is cholinergic dependent and that beta-adrenergic tone and ganglionic transmission do not participate in PACAP-induced release of PYY. PACAP may play a role in the neural regulation of PYY release.

Insulinlike growth factor-binding protein modulates the growth response to insulinlike growth factor 1 by human gastric cancer cells

BACKGROUND

This study determined whether the resistance to the mitogenic effect of insulinlike growth factor 1 (IGF-1) in AGS (we found that IGF-1 had almost no effect on the growth of AGS) cells is caused by the absence of IGF-1 receptor on the cells or by the interference of endogenous IGFs and IGF-binding protein (IGFBP).

METHODS

IGF-1 receptors were examined by radioligand binding assay. The protein in conditioned medium and the molecular weight of IGF-1 receptors on AGS cells were determined by affinity cross-linking with 125I-IGF-1 followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Messenger RNAs for IGF-1, IGF-2, and IGFBP-4 were detected by Northern analysis.

RESULTS

AGS cells possessed a single class of high-affinity binding sites for IGF-1 (dissociation constant [Kd], 0.51), with a binding capacity approximately 4 x 10(4) sites per cell. The size of the alpha subunit of IGF-1 receptors on cell membranes was approximately 130 kilodaltons. des (1-3) IGF-1, a truncated IGF-1 with very low affinity to IGFBPs, stimulated AGS cell growth in dose-dependent fashion. The medium conditioned by AGS cells contained IGFBPs of 27-32 and 37-42 kilodaltons. AGS cells expressed messenger (mRNA) RNAs for IGF-2 and IGFBP-4 but not for IGF-1, whereas another gastric carcinoma cell line (SIIA), whose growth is stimulated by IGF-1, expressed mRNA IGF-2 but did not express mRNA for IGF-1 or IGFBP-4:

CONCLUSIONS

The relative absence of growth response of AGS cells to IGF-1 is due to the endogenously produced IGFBPs sequestering IGF-1 and preventing receptor interaction.

Radioimmunoimaging of xenograft pancreatic cancer with 131I-monoclonal antibody P2

Monoclonal antibodies (McAbs) to pancreatic cancer were developed by fusing SP2/0 cells and splenocytes from Balb/c mice immunized with CH-2 cells. The specific binding rates of McAb P1 and P2 were 40.1 and 43.8%, respectively, shown by binding radioreactivity assay in vitro, which were in sharp contrast with those of control groups (p < 0.05). The biodistribution of radioiodinated McAb P2 was studied by measuring parameters of tumor-specific radioreactivity in nude mice bearing CH-2 tumors. The ratios of tumors to nontumors were all > 2 at 48 h. The localization index of cancer and the ratio of tumor to pancreas were 4.05 and 4.16, respectively, at 72 h. Therefore, 131I-McAbs may be useful for radioimmunoimaging (RII) of pancreatic cancer. After intraperitoneal injection of 131I-McAb P2 into tumor-bearing nude mice, imaging of xenograft pancreatic cancer became increasingly distinct with the nonspecific background fading, especially in the period of 72-96 h. Examination of pancreatic cancer tissues by immunohistochemical methods revealed that McAb P2 was strongly positive (86%) in comparison with other tumors and normal tissues. The results demonstrated that clinical RII of pancreatic cancer was feasible with McAb P2.

Neurotensin regulates growth of human pancreatic cancer

OBJECTIVE

The effect of neurotensin (NT) on in vitro-growth of human pancreatic cancer cells (MIA PaCa-2) was examined. Furthermore, the intracellular signal-transduction pathways by which neurotensin regulates growth of MIA PaCa-2 cells were determined.

SUMMARY BACKGROUND DATA

NT is trophic for normal rat pancreas, but the effect of NT on growth of human pancreatic cancer is not known.

METHODS

Effects of NT (10(-12) to 10(-6) mol/l) on growth of MIA PaCa-2 cells were determined by both count of cell numbers and 3H-thymidine incorporation. Action of NT on phosphatidylinositol (PI) hydrolysis, cyclic AMP production, and intracellular calcium level were determined by conventional methods. The effects of 8-bromo-cyclic AMP and prostaglandin E2 on cell growth were determined.

RESULTS

Low concentrations of NT (10(-12) to 10(-9) mol/l) stimulated growth in a dose-dependent manner, but higher concentrations of NT (10(-8) to 10(-6) mol/l) did not stimulate growth of MIA PaCa-2 cells. NT (10(-12) to 10(-6) mol/l) stimulated PI hydrolysis and increased intracellular calcium levels in a dose-dependent manner. High concentrations of NT (10(-8) to 10(-6) mol/l) stimulated production of cyclic AMP in a dose-dependent manner. 8-bromo-cyclic AMP inhibited growth of MIA PaCa-2 cells; prostaglandin E2 did not affect growth of MIA PaCa-2 cells.

CONCLUSIONS

NT stimulates growth of MIA PaCa-2 cells through stimulation of PI hydrolysis and mobilization of calcium. Stimulation of the cyclic AMP pathway by high concentrations of NT abolishes the growth-stimulatory effect of NT that is mediated through PI hydrolysis or calcium mobilization.

Progressive loss of pancreatic function in chronic pancreatitis is delayed by main pancreatic duct decompression. A longitudinal prospective analysis of the modified puestow procedure

OBJECTIVE

This study evaluated the effect of operative drainage of the main pancreatic duct (MPD) on functional derangements associated with chronic pancreatitis (CP).

SUMMARY BACKGROUND DATA

The author previously reported delayed functional impairment in an evaluation of the impact of operative drainage in patients with CP. The author now reports on a prospective study of 143 patients with this diagnosis.

METHODS

Each patient underwent 1) ERCP, 2) the Bentiromide PABA, 3) 72-hour fecal fat test, 4) oral glucose tolerance test (OGTT) and 5) fat meal (LIPOMUL)--stimulated pancreatic polypeptide release (PP). All patients were stratified as mild/moderate (M/M) or severe CP on the basis of a 5-point system that was developed by the author. Patients were studied at 16-month intervals.

RESULTS

All 143 patients underwent initial and follow-up evaluations in a mean follow-up of 47.3 months; 83 of 143 patients had M/M grade at initial evaluation. Eighty-seven patients underwent (MPD) decompression to relieve abdominal pain. In a separate prospective 17 patients with a diagnosis of CP, a grade of M/M and non-disabling abdominal pain were randomized to operative or non-operative treatment; 9 of these randomized patients were operated upon and 8 were not. No patient improved their grade during follow-up; 47 of 83 M/M patients had operative drainage and 36 did not. This grade was preserved in 41 of 47 (87%) operated patients but in only 8 of the 36 non-operated patients (22%). In the randomized trial, seven of nine operated patients retained their functional status in follow-up, whereas only two of eight patients (25%) randomized to non-operation preserved their functional grade.

CONCLUSIONS

These data in this large study as well as among a previous randomized sample, support a policy of early operative drainage before the development of irreversible functional impairment in patients with chronic pancreatitis and associated dilation of the main pancreatic duct.

Age-related changes in gallbladder contractility and cytoplasmic Ca2+ concentration in the guinea pig

Gallbladder (GB) motility diminishes with aging. This study was performed to characterize mechanisms that are involved in changes in GB contractility that occur during aging. Cytoplasmic Ca2+ concentrations ([Ca2+]i) and the contractile force of guinea pig GB muscle strips were simultaneously measured using fura-2 and force-displacement transducers. The binding ability of the Ca2+ channel antagonist and GB muscle compliance were also examined. The COOH-terminal octapeptide of cholecystokinin (CCK-8) evoked a dose-dependent increase in force and [Ca2+]i. Changes of [Ca2+]i and contractile force of muscle strips in response to CCK-8 were significantly greater in young (2 mo old) compared with mature and aged (12 and 24 mo old) guinea pigs (changes in [Ca2+]i, ED50: 46.1 nM at 2 mo, 6.1 microM at 12 mo, and 2.8 mM at 24 mo; changes of contractile force, ED50: 24.8 microM at 2 mo, 2.1 mM at 12 mo, and 357 mM at 24 mo). However, the magnitude of the contraction at each percent change in [Ca2+]i was actually similar in young and aged guinea pigs. In a Ca(2+)-free buffer, the responses of [Ca2+]i and force to CCK-8 in both young and aged GB muscles decreased, but those were still dose and age dependent. Binding ability of the Ca2+ channel antagonist did not differ in the young and aged groups, but the compliance of the GB muscle strip decreased with aging. These results suggest that both a reduced mobilization of intracellular Ca2+ and a decreased muscle compliance are responsible, at least in part, for age-related reduced contraction of guinea pig GB in response to CCK.

Age-related changes in duodenal adaptation after distal small bowel resection in rat

Two groups of male Fisher 344 rats (young: 4 months old; aged: 25 months old) underwent either 70% distal small bowel resection or sham operation (small bowel transection). Rats from each treatment group of each age were sacrificed on the 10th (N = 15: young rats; N = 13: aged rats) or 20th (N = 15: young; N = 13: aged) postoperative day (POD), and the duodenal mucosa was weighed and assayed for DNA, RNA, and protein contents, as well as for specific activities of the disaccharidase, sucrase, maltase, and lactase. Compared to the sham operation, distal small bowel resection significantly increased DNA by 48%, RNA by 122%, and protein by 75% in young rats and DNA by 40%, RNA by 92%, and protein by 71% in aged rats on the 20th POD. Both young and aged rats showed similar adaptive hyperplasia on the 10th POD. On the 20th POD after distal small bowel resection, specific activities of all tested enzymes were significantly increased in young rats (sucrase +86%, maltase +110% and lactase +64%), but showed no significant changes in aged rats. These findings suggest that the duodenum of aged rats may have sufficient proliferative potential to respond to distal small bowel resection, but that the mechanisms governing return of function in response to distal small bowel resection are inhibited in aged rats, compared to those mechanisms in the young.