Complications of neonatal extracorporeal membrane oxygenation. Collective experience from the Extracorporeal Life Support Organization.

Since 1973, 7667 neonates have been treated with extracorporeal membrane oxygenation for severe respiratory failure and their cases reported to the Extracorporeal Life Support Organization Registry. The overall survival was 81% in these neonates, who were thought to have a survival of 20% without extracorporeal membrane oxygenation. A total of 4322 mechanical complications (0.56 +/- 0.84 per case) and 13,827 patient complications (1.80 +/- 2.12 per case) were reported overall. The most common mechanical complications included clots in the circuit (19%), cannula placement (9%), oxygenator failure (4%), and others (9%). Common patient complications included cardiopulmonary (43%), neurologic (35%), bleeding (35%), metabolic (32%), renal (25%), and renal (25%), and infectious (9%). From the initial experience to 1988 the average number of mechanical complications per case was 0.27 per case and this significantly increased during 1990 to 1992 to 0.75 per case (p < 0.05). Likewise, from 1973-1985 to 1988 the average patient complications per case were 1.44 per case and this significantly increased during 1990 to 1992 to 2.10 per case. During the same periods, patient survival significantly decreased from 84% (1973-1985 to 1988, n = 2463) to 80% (1990 to 1992, n = 4005). Venovenous double-lumen single cannula extracorporeal membrane oxygenation had a higher survival than venoarterial extracorporeal membrane oxygenation (91% versus 81%) and a lower rate of major neurologic complications. The incidence and survival with seizures (6% and 89% venovenous versus 13% and 61% venoarterial) or cerebral infarction (9% and 69% venovenous versus 14% and 46% venoarterial) was significantly lower with the venovenous method and appeared to have a substantial impact on overall survival. The correlation of patient complication rate and total complication rate with survival was highly significant, however, causality cannot be established. Explanations for the increase in complications, relative to a decrease in survival, despite a growing nationwide experience include (1) increased complexity of cases as many programs expand entry criteria (more premature infants, infants with grade 1 or 2 intracranial hemorrhage, and complex congenital diaphragmatic hernia), (2) a growing number of programs with fewer cases per program, yet greater accessibility, (3) less reluctance to report complications encountered during extracorporeal membrane oxygenation as group experience grows, and (4) changes in the Extracorporeal Life Support Organization data form to be more inclusive of more minor complications.

Complications of neonatal extracorporeal membrane oxygenation.

From 1973-1985 to 1988 the average patient complications per case were 1.44 per case and significantly increased during 1990 to 1992 to 2.10 per case (Figure 3). During the same periods patient survival significantly decreased from 84% (1973-1985 to 1988, n = 2463) to 80% (1990 to 1992, n = 4005) (Figure 4). The association between total complication rates and survival rate was examined by regression analysis (Table 5). The correlation of patient complication rate and total complication rate with survival is highly significant; however, causality cannot be established. When comparing different entry criteria (Table 2) for incidence of mechanical and patient complications, no significant differences are apparent. This is not surprising since each of the entry criteria were designed to identify the same patient population. When premature neonates (> 35 weeks) were placed on ECMO, 36% of them had intracranial haemorrhage (ICH) with 62% mortality while only 12% of the neonates < 35 weeks had ICH and a 49% mortality. Similar findings were noted with low birthweight neonates (< 2.2 kg), 28% had ICH with 64% mortality while only 12% of the neonates > 2.2 kg had ICH with a 50% mortality. Selection criteria remain problematic for a variety of reasons. They cannot be viewed as absolute because of variability between centres. What represents likely 80% mortality in one centre may not apply to another. Historical controls are misleading because changing respiratory therapy strategies make historical populations difficult to compare. Also, once an ECMO centre becomes established, a more challenging group of patients will be attracted than previously was the case. Further, a single entry criterion cannot be generalized for all entry diagnoses. Criteria for an 80% predicted mortality is probably not the same for MAS, CHN, PPHN, and sepsis. Subsequent patients registered in the Neonatal ECMO Registry of the Extracorporeal Life Support Organization will address these issues more thoroughly, as specific details of the pre-ECMO condition and therapeutic strategies are collected. This collective review should help to identify trends which require reassessment of technique or patient management.

Bombesin stimulates growth of human gastrinoma.

BACKGROUND: We have previously reported the first establishment and characterization of a functioning human gastrinoma (PT) xenograft. Bombesin, the equivalent of the mammalian gastrin-releasing peptide, has trophic effects on normal and neoplastic tissues of the gastrointestinal tract; the effects of gut hormones on the growth of gastrinoma are not known. The purpose of this study was twofold: (1) to determine the presence of various gut peptides in PT and (2) to determine the effect of bombesin on the growth of PT xenografts. METHODS: PT tumors were examined for expression (mRNA and protein) of various gut peptides by Northern hybridization and immunohistochemistry. In addition, PT xenografts were implanted as 3 mm2 pieces bilaterally subcutaneously in athymic nude mice. Mice were divided into two groups to receive either bombesin (5 micrograms/kg) or saline administered as intraperitoneal injections every 8 hours. Tumor area was measured twice weekly until mice were sacrificed (day 28), when tumor and normal pancreas were removed, weighed, and assayed for DNA and protein content. RESULTS: Both mRNAs and peptides of gastrin and chromogranin A were present in PT tumors. Bombesin significantly stimulated growth of PT tumors from day 18 until mice were sacrificed (day 28). As expected, bombesin stimulated pancreatic growth. CONCLUSIONS: We have demonstrated for the first time that bombesin is a trophic hormone for gastrinoma. The unique cell line PT contains gastrin and chromogranin A and will be a useful model to define the biologic mechanisms controlling the growth of human gastrinomas.

The role of endogenous prostaglandins in hormone-stimulated pancreatic exocrine secretion.

The authors have previously shown that neurotensin and secretin inhibit gastric acid secretion in the dog and that these actions are inhibited by the prostaglandin synthesis inhibitor indomethacin. Conversely, neurotensin and secretin share similar stimulatory effects on pancreatic exocrine secretion. In the present study, the effects of blockade of prostaglandin synthesis by indomethacin on neurotensin-, cholecystokinin-, and secretin-stimulated exocrine secretion are examined along with the effects of these same agents on the release of pancreatic polypeptide. The studies were performed on conscious dogs with chronic gastric and pancreatic cannulas. Dose-dependent increases in pancreatic exocrine secretion of water and bicarbonate were observed with IV infusion of neurotensin or secretin; however, inhibition of prostaglandin synthesis by indomethacin abolished this response. Protein secretion stimulated by either neurotensin or cholecystokinin was not affected by prostaglandin inhibition. Cholecystokinin and neurotensin infusion stimulated release of pancreatic polypeptide; only neurotensin-stimulated release of pancreatic polypeptide was inhibited by indomethacin treatment. It is concluded that intact prostaglandin synthesis is necessary for the actions of neurotensin and secretin (but not that of cholecystokinin) on pancreatic exocrine secretion of water and bicarbonate and for neurotensin- (but not cholecystokinin-) stimulated release of pancreatic polypeptide.

Establishment and characterization of a human carcinoid in nude mice and effect of various agents on tumor growth.

The authors have established a long-term tissue culture cell line (BON) derived from a metastatic human carcinoid tumor of the pancreas. The cells have been in continuous passage for 46 months. Tissue culture cells produce tumors in a dose-dependent fashion after SC inoculation of cell suspensions in athymic nude mice. BON tumors, grown in nude mice, are histologically identical to the original tumor; they possess gastrin and somatostatin receptors, synthesize serotonin and chromogranin A, and have a doubling time of approximately 13 days. The antiproliferative effects of the long-acting somatostatin analogue, SMS 201-995 (300 micrograms/kg, t.i.d.), and 2% alpha-difluoromethylornithine on BON xenografts in nude mice were examined. Tumor size was significantly decreased by day 14 of treatment with either agent and at all points of analysis thereafter until the animals were killed (day 33). In addition, tumor weight, DNA, RNA, and protein contents were significantly decreased in treated mice compared with controls. Establishment of this human carcinoid xenograft line, BON, provides an excellent model to study further the biological behavior of carcinoid tumors and the in vivo effect of chemotherapeutic agents on tumor growth.

Coronary-subclavian steal syndrome following coronary artery bypass grafting.

Angina pectoris resulting from the coronary-subclavian steal syndrome is a rare phenomenon with only 10 previously reported cases. However, with the increasing use of the internal mammary artery in the coronary artery bypass graft (CABG) procedure it may be encountered more frequently in the future. We report our recent experience with coronary-subclavian steal syndrome after CABG with 2 patients in whom complete relief from angina pectoris was obtained following bypass of a proximal subclavian artery occlusion in one patient and improvement of angina in the other. A review of the relevant literature is also presented.

The effect of tumor burden on ornithine decarboxylase activity in mice.

Polyamines are essential for cell growth of normal and neoplastic tissue, alpha-Difluoromethylornithine (DFMO) is a known irreversible inhibitor or ornithine decarboxylase (ODC), the rate-limiting enzyme in polyamine biosynthesis. The purpose of this study was to examine the effects of tumor burden on ODC in tissues of tumor-bearing compared with tumor-free mice. Twenty-eight male Balb/c mice were divided into four groups of 7 each. Groups 1 and 2 were inoculated subcutaneously with 10 x 10(6) MC-26 mouse colon adenocarcinoma cells. Groups 3 and 4 were kept as tumor-free controls. Ten days after inoculation, groups 2 and 4 were injected with DFMO (200 mg/kg) intraperitoneally (IP) while Groups 1 and 3 received saline. Two hours after the injection of DFMO the animals were sacrificed. The tumor, pancreas, kidney, and liver were excised and analyzed for ODC activity. DFMO caused a significant reduction (compared with controls that did not receive DFMO) in the ODC activity of tumors; however, ODC activity of the kidney, pancreas, and liver of tumor-bearing mice was not affected. Additionally, the basal ODC activity in the kidney, liver, and pancreas of tumor-bearing mice was significantly lower compared with tumor-free controls. DFMO lowered ODC activity in the kidney, pancreas, and liver of tumor-free mice. These results suggest that the presence of MC-26 tumor causes systemic effects that alter ODC activity and the response to a known inhibitor of ODC.

Differential sensitivity of various human tumors to inhibition of polyamine biosynthesis in vivo.

Polyamines are essential for normal and neoplastic growth. Ornithine decarboxylase (ODC) is the first and rate-limiting enzyme in the polyamine biosynthetic pathway. alpha-Difluoromethylornithine (DFMO) is an enzyme-activated irreversible inhibitor of ODC, and a known anti-neoplastic agent. The purpose of this study was to examine the susceptibility of various human cancers to inhibition by DFMO in vivo. We have studied three human pancreatic adenocarcinomas, designated CAV, SKI, and PGER, two human colon adenocarcinomas (LS-180 and WIDR), and three metastatic cell lines of a human gastric adenocarcinoma (BHM, BMM, BLM) that were growing in congenitally athymic (nude) Balb/c mice. Mice bearing each tumor were divided into two groups; one group served as controls and the other group received DFMO 3% in drinking water. Tumor growth and weight, and content of DNA, RNA, protein and polyamines were determined and correlated. DFMO significantly inhibited the growth of three of the three gastric tumors, two of the three pancreatic tumors and neither of the two colon tumors. The tumor content of DNA, RNA and protein exhibited a pattern that was parallel to tumor growth. The tumor polyamine concentration did not correlate with sensitivity to DFMO. These findings provide clear evidence for important differences in the sensitivity of various human cancers to growth inhibition by DFMO and indicate that endogenous polyamine levels alone do not predict the sensitivity of the tumors to DFMO.

Intravenous amino acids stimulate human gallbladder emptying and hormone release.

Gallbladder stasis during prolonged total parenteral nutrition (TPN) has been documented. We have examined the effect of intravenous amino acid infusion on human gallbladder contraction and release of cholecystokinin (CCK). Five healthy adult volunteers were given amino acid infusions at different rates (65, 125, 240, and 600 mg.kg-1.h-1). The volume of the gallbladder was calculated by means of ultrasonographic measurements. Plasma samples were analyzed for CCK immunoreactivity. Gallbladder and hormone responses after intravenous amino acids were compared with responses after a fat meal, after a protein meal, and after ingestion of an oral amino acid mixture. We found that intravenous amino acids stimulated human gallbladder contraction in a dose-related manner. The mechanism of stimulation may be through the release of CCK although significant correlation was not demonstrated. The magnitude of response is similar to that seen after meal stimulation. To compare the delivery of amino acids during a standard meal and during each dose of intravenous amino acids, peripheral plasma levels of dietary amino acids were measured after a standard commercially prepared enteral supplement meal and after each dose of intravenous amino acids. Our lower doses of amino acid infused resulted in levels of circulating amino acid comparable to those after a meal. The induction of gallbladder contraction and release of CCK in human recipients of parenteral nutrition may be of value in some circumstances.

In vivo comparison of inhibition with proglumide and CR-1409 of cholecystokinin-induced pressure in the biliary tract of the guinea pig.

This study was done to compare the effects of two cholecystokinin antagonists, proglumide and CR-1409, on cholecystokinin-induced changes in intrabiliary pressure in vivo. We have substantially modified the constant infusion biliary manometry model, successfully used in large animals, to measure contractility of the gallbladder in guinea pigs. A silicone catheter for manometry was placed in the fundus of the gallbladder of an anesthetized guinea pig, and the biliary tree was constantly infused at 0.1 milliliter per minute with normal saline solution. The intraluminal pressure of the system was continuously recorded. The model was used to demonstrate a dose-response curve to bolus administration of exogenous cholecystokinin (0.01 to 1.0 nanomole per kilogram) and also to study the actions of proglumide, an antagonist to gastrin and cholecystokinin, and CR-1409, a newer, specific cholecystokinin antagonist, on cholecystokinin-induced contraction of the gallbladder of the guinea pig in vivo. Proglumide, at a dose of 5 millimoles per kilogram, completely abolished increases in intrabiliary pressure caused by cholecystokinin (0.5 nanomole per kilogram), whereas this effect was achieved by only 5 micromoles per kilogram of CR-1409. In both, there was full recovery from cholecystokinin antagonism within one hour. CR-1409 is one thousand times more potent than proglumide against cholecystokinin-induced changes in intrabiliary pressure in vivo and appears to be a useful pharmacologic reagent to study cholecystokinin-mediated components of physiologic contraction of the gallbladder.

Effect of oral fat on plasma levels of neurotensin and neurotensin fragments in humans. Characterization by high-pressure liquid chromatography.

The effect of ingestion of fat (Lipomul 1 g/kg) on the circulating levels of neurotensin (NT1-13) and amino-terminal fragments (NT1-8, NT1-11) and carboxy-terminal fragment (NT8-13) of NT were investigated in six healthy male volunteers. NT and NT fragments were extracted from plasma collected at 0, 15, 30, and 60 min after ingestion of fat, and the plasma levels of NT1-13 and NT fragments were characterized using high-pressure liquid chromatography and radioimmunoassay techniques. Significant elevations of plasma levels of NT1-8, NT1-11, and NT1-13 were observed at 15, 30, and 60 min after fat ingestion. The maximum elevations were 273% for NT1-8, 234% for NT1-11, and 54% for NT1-13. NT8-13 levels failed to rise significantly when compared to basal levels. These findings indicate that both the amino-terminal and carboxy-terminal fragments of NT are either released along with intact NT or are formed as metabolites from NT1-13 in response to ingestion of fat in man.

2-Deoxy-D-glucose inhibits the antitumor effects of alpha-difluoromethylornithine on the growth of colon cancer in vivo.

The glycolytic inhibitor, 2-deoxy-D-glucose (2-DG), has been shown to inhibit the growth of certain cancers. alpha-Difluoromethylornithine (DFMO) is an irreversible inhibitor of ornithine decarboxylase (ODC), the rate-limiting enzyme in polyamine biosynthesis. DFMO has been shown to inhibit cancer growth in a number of models. The present study was designed to investigate the effects of 2-DG alone and combined with DFMO on MC-26 mouse colon adenocarcinoma tumors growing in vivo. Twenty-eight male Balb/c mice were inoculated with 250,000 MC-26 cells, and then randomized into four groups of 7 each: group I served as control; group II received DFMO (3% in drinking water); group III received 2-DG (500 mg/kg/d IP); group IV received combination of 2-DG and DFMO. Treatment began 5 days after tumor cell inoculation. MC-26 tumor area was reduced 73% by DFMO compared to a 24% reduction caused by 2-DG. The tumor weight was reduced 80% by DFMO and 52% by 2-DG. The tumor contents of DNA, RNA, and protein were significantly reduced by DFMO but not 2-DG. The tumor concentration of the polyamines putrescine and spermidine were reduced by DFMO alone or combined with 2-DG while spermine levels remained unchanged. 2-DG alone did not alter polyamine levels. These results indicate that both 2-DG and DFMO, when added as single agents, inhibit tumor growth. However, the addition of 2-DG to the DFMO regimen inhibited the antitumor effects of DFMO. Survival studies performed on MC-26 cells in vitro corroborated the antagonisms between DFMO and 2-DG that were shown in vivo.

Clinical significance of gastrin receptors in human colon cancers.

We have measured gastrin receptors (GR) in surgical specimens from 67 patients with primary colon cancers in order to determine the clinical significance of GR in colon cancer. GR analysis was performed on these specimens, and 22 cancers (32.8%) had no detectable GR. Thirty-eight cancers (56.7%) had high-affinity (Kd less than 1.0 nM) levels of GR. Seven cancers (10.4%) had only low-affinity GR (Kd greater than 1.0 nM). Twenty patients (29.9%) had cancers with GR greater than 10 fmol/mg protein. Mean GR content was significantly greater (11.8 +/- 2.9 fmol/mg protein) in Dukes' Stage A and B cancers when compared to Stage C and D cancers (6.2 +/- 1.6 fmol/mg protein). A significantly greater percentage (52.4%) of patients in the early stages (A and B) had tumors with greater than 10 fmol/mg protein compared to patients with more advanced (C and D) cancers (19.6%). GR content did not correlate with histological differentiation, patient age, or preoperative carcinoembryonic antigen levels. No difference in the GR content was noted between left and right colon cancers or in patients of different sex or race. GR content of normal colon mucosa correlated with the GR content of colon cancers from the same surgical specimen, suggesting that these tumors maintain their normal complement of GR. In the early period of follow-up, 12 of 43 (28%) Stage C and D patients with GR less than 10 fmol/mg protein have died, whereas all 8 Stage C and D patients with GR greater than 10 fmol/mg protein are alive. GR content of colon cancers may have prognostic significance and may identify a group of patients with colon cancer that may benefit from hormonal therapy with antigastrin drugs.

Species-specific effects of neurotensin on gallbladder contraction in vitro.

We have previously shown that an in vivo administration of neurotensin (NT) stimulates contraction of dog gallbladder (GB), but produces dilatation of GB in humans. The objective of this study was to examine the effect of NT on human, dog, guinea pig, and rabbit GB in vitro, in order to delineate direct versus indirect actions of NT in different species and to evaluate the structure-activity relationships of NT. The effect of NT on the canine sphincter of Oddi (SOD) was also examined in vitro. Isolated longitudinal strips of GB from the four species given above and SOD from dogs were suspended in oxygenated Krebs buffer, and the isometric tension responses to various doses of NT, NT 8-13, NT 1-11, and xenopsin (XP) were determined. All the NT homologs, except NT 1-11, stimulated contraction of the dog GB and SOD in a dose-dependent manner. NT also caused dose-related stimulation of GB contraction from guinea pigs but did not stimulate or depress the contractile activity of human and rabbit GB strips. These results suggest that NT action on GB contraction is species-specific. Tetrodotoxin did not modify the contraction of dog GB and SOD in response to NT, indicating that NT mediates its contractile effects directly. The relaxing effect of NT on GB of humans in vivo, as previously reported by us, thus appears to be an indirect action.(ABSTRACT TRUNCATED AT 250 WORDS)

Development and age-related changes in pancreatic cholecystokinin receptors and duodenal cholecystokinin in guinea pigs.

We have investigated the changes associated with development and aging on the interrelationships between cholecystokinin (CCK) and the pancreas in the guinea pig. Three groups (1 month old, 1 year old, and 3 years old) of male guinea pigs were sacrificed while feeding in order to measure food-stimulated levels of CCK in blood and in duodenal mucosa by radioimmunoassay (RIA), as well as the pancreatic concentrations of CCK receptors. Systemic blood concentrations of CCK did not change with age. However, the concentration and content of CCK in duodenal mucosa increased more than 3-fold with age. A single class of high-affinity (KD less than or equal to 0.1 nM) CCK-receptor was found on the pancreatic membranes. The concentration (fmol/mg protein) of these receptors significantly diminished by one-half with increasing age. We also found an apparently similar fall in the receptor-binding affinity, but the difference was not significant. We conclude that in the guinea pig, duodenal content of CCK increases so as to compensate for the decreasing concentration of pancreatic CCK receptors, or, perhaps, vice versa. The diminished exocrine function of the pancreas, seen with increasing age, may well reflect both the diminished number of CCK-receptors and the reduction of pancreatic acinar cells.

Establishment of a human gastrinoma in nude mice.

We report the first establishment and characterization of functioning gastrinoma from a human being transplanted into nude mice. Tissue was obtained at operation from a gastrinoma liver metastasis from a patient with the Zollinger-Ellison syndrome. The tumor was implanted subcutaneously in five athymic nude mice. Serum gastrin was measured by means of radioimmunoassay in specimens of mouse blood taken before and 5 minutes after intraperitoneal injection of secretin (100 micrograms/kg). In a second experiment serum gastrin was measured 30 minutes after injection of somatostatin analogue, SMS 201-995 (300 micrograms/kg). Studies were also done in 10 control mice. At passage, the fundus of each tumor-bearing mouse was weighed and examined microscopically. The gastrinoma (tumor line, PT) has been maintained for 34 months through four passages with a tumor doubling time of 37 to 45 days. The histology is similar to the original tumor. Immunocytochemistry showed that PT contained gastrin. In two mice metastasis developed 9 months after implantation. Gastrin levels in mice bearing PT have ranged from 216 to 12,000 pg/ml. Gastrin levels of control mice ranged from 0 to 63 pg/ml. Secretin increased gastrin levels in three of five mice tested and decreased gastrin levels in two mice. Repeat secretin tests showed identical results. SMS 201-995 decreased gastrin levels from basal values. Fundic weight of mice bearing PT (397 +/- 93 mg) was significantly greater than control fundic weight (180 +/- 26 mg). Gastrinomas growing in nude mice produce physiologically active gastrin as shown by elevated serum gastrin levels and by hyperplasia of the stomach. Two distinct subpopulations of gastrinoma cells respond differently to secretin. This model should provide important information on mechanisms of growth control and on gastrin release by gastrinomas in human beings.

Influence of endogenous prostaglandins on secretin-mediated inhibition of gastric acid secretion in dogs.

The influence of endogenous prostaglandins on secretin-mediated inhibition of gastric acid secretion was examined in 6 mongrel dogs with Thomas gastric and Herrera pancreatic cannulas. The dogs were given intravenous pentagastrin (1 microgram/kg.h) during the 180-min experiment, and graded doses of secretin (0.3-1.5 micrograms/kg.h) (1-5 CU/kg.h) were infused intravenously between 60 and 120 min. In alternate, otherwise identical experiments, a prostaglandin synthesis inhibitor, either indomethacin or meclofenamate, was also administered throughout the experiment. Increasing doses of secretin led to increasing inhibition of gastric acid output with the maximum inhibition at 1 microgram/kg.h (3.3 CU/kg.h) of secretin. Both indomethacin and meclofenamate abolished the inhibitory effects of secretin on gastric acid secretion. The inhibitors of prostaglandin generation had no effect on the serotonin system. We concluded that secretin mediates its inhibitory action on gastric acid secretion, at least in part, through endogenous prostaglandins.

Polyamine levels and gastrin receptors in colon cancers.

Polyamines and gastrin receptors (GR) were studied in samples of colon cancer and mucosa from 40 patients and in control mucosa from 11 patients without cancer. Polyamines (i.e., putrescine, spermidine, spermine) are essential for growth and differentiation. The concentration of polyamines is elevated in rapidly proliferating normal tissues and in some cancers. The presence of GR in human colon cancers has been previously reported. The purpose of the present study was twofold: (1) to determine whether polyamine levels are elevated in colon cancers and in adjacent normal colon mucosa compared to colon mucosa from patients without cancer; and (2) to examine the relationship between polyamine levels and GR in colon cancers. Polyamine levels in colon cancers were significantly higher than in the normal colon mucosa from the same patients. The polyamines, spermidine and spermine, were significantly higher in colon mucosa from patients with cancer compared to patients without cancer. Spermidine and the spermidine:spermine ratio, an index of cell proliferation, were increased in colon cancers with GR compared to cancers without GR. There were no significant correlations between polyamine levels and the following: patient age, CEA level, site of cancer, stage, or differentiation. Because polyamine levels are increased in colon mucosa from patients with cancer, measurement of polyamines may detect patients at risk for subsequent development of colon cancer. Increased levels of polyamines in colon cancers with GR is evidence that gastrin may play a trophic role in human colon cancers.

Inhibition of human gastric adenocarcinoma xenograft growth in nude mice by alpha-difluoromethylornithine.

We studied the effect of inhibition of polyamine biosynthesis by alpha-difluoromethylornithine on the growth of a human gastric adenocarcinoma (CLEES) xenotransplanted in nude mice. CLEES is a well-differentiated gastric adenocarcinoma of the intestinal type. The doubling time has ranged from 7 to 10 days through 11 passages. Electron microscopic and immunohistochemical studies comparing the original tumor and xenotransplants showed similar structure and similar amounts of carcinoembryonic antigen. Polyamine biosynthesis is required for cell division. alpha-Difluoromethylornithine inhibits ornithine decarboxylase, the rate-limiting enzyme in polyamine biosynthesis. In this study, 48 athymic mice were used in two experiments. In the first experiment, two groups of 12 mice each were inoculated with CLEES tumor cells and received either tap water or a 3% alpha-difluoromethylornithine solution as drinking water. Tumor size was measured twice weekly. Tumor size was significantly decreased from controls by the fourth week of treatment and at all points of analysis thereafter for 7 wk. In the second experiment, alpha-difluoromethylornithine significantly reduced tumor concentrations of the polyamines putrescine and spermidine. In addition, the tumor content of DNA was significantly reduced in treated mice (0.64 +/- 0.16 mg) compared to controls (4.76 +/- 0.92 mg). Our data suggest that inhibition of polyamine biosynthesis may be a useful component of multidrug chemotherapy for human gastric adenocarcinoma. Establishment of tumor lines such as this gastric adenocarcinoma will facilitate further studies on the biological behavior of human gastric cancer and its response to chemotherapeutic manipulation in vivo.

Regulation of the release of cholecystokinin by bile salts in dogs and humans.

The objective of these studies was to investigate the role of bile salts in the regulation of release of cholecystokinin in response to nutrients in dogs and humans. In dogs, the intraduodenal administration of a bile salt sequestrant, cholestyramine (2, 4, or 8 g/h), resulted in a dose-related enhancement of the release of cholecystokinin-33/39 and pancreatic protein secretion in response to intraduodenal administration of amino acids. Intraduodenal administration of cholestyramine alone did not affect basal levels of cholecystokinin-33/39 or pancreatic protein secretion. Total diversion of bile also significantly increased the release of cholecystokinin and pancreatic protein secretion in response to intraduodenal administration of amino acids. Replacement of the bile salt pool by intraduodenal administration of taurocholate completely reversed the enhancement effect of both cholestyramine and bile diversion. In humans, oral ingestion of cholestyramine (12 g) significantly increased the release of cholecystokinin-33/39 and gallbladder contraction in response to the oral ingestion of either a triglyceride or amino acids. These results support a physiologic role of bile salts in the negative feedback regulation of release of cholecystokinin in response to luminal nutrients.