Frequent mutation of the E2F-4 cell cycle gene in primary human gastrointestinal tumors

The E2F group of transcription factors transactivates genes that promote progression through the G1-S transition of the cell cycle. Members of the retinoblastoma (Rb) family of proteins bind to E2Fs and inhibit this function. E2F-4, one example of the E2F group, functions as an oncogene when transfected into nontransformed cells in vitro. On the other hand, mice that are homozygously lacking a normal E2F-1 gene develop cancers, consistent with a tumor-suppressive role for this gene. The exact function of E2Fs has thus been unclear; moreover, direct involvement of this gene in primary human tumorigenesis has not been shown. We, therefore, investigated mutation within the E2F-4 coding region in 16 primary gastric adenocarcinomas, 12 ulcerative colitis-associated neoplasms, 46 sporadic colorectal carcinomas, 9 endometrial cancers, and 3 prostatic carcinomas. We limited our investigation to the serine repeat within E2F-4, reasoning that this tract might be altered in genetically unstable tumors (replication error-positive, or RER+). All tumors were RER+, with the exception of a control group of 15 RER- sporadic colorectal carcinomas. PCR with incorporation of [32P]dCTP was performed using primers flanking the serine trinucleotide (AGC) repeat. Twenty-two of 59 gastrointestinal tumors (37%) contained E2F-4 mutations; these comprised 5 of 16 gastric tumors (31%), 4 of 12 ulcerative colitis-associated neoplasms (33%, including 1 dysplastic lesion), and 13 of 31 sporadic colorectal cancers (42%). No mutation was present in any of the endometrial, prostate, or RER- colorectal tumors. Of note, homozygous mutations occurred in three cases, and two of seven informative patients showed loss of one E2F-4 allele in their tumors. Furthermore, the RER+ sporadic colorectal tumors were evaluated at trinucleotide repeats within the genes for N-cadherin and B-catenin; no tumors demonstrated mutation of these genes. These data suggest that E2F-4 is a target of defective DNA repair in these tumors.

Famotidine for healing and maintenance in nonsteroidal anti-inflammatory drug-associated gastroduodenal ulceration

BACKGROUND & AIMS

Nonsteroidal anti-inflammatory drugs (NSAIDs) are strongly associated with gastroduodenal ulceration. How to manage patients with NSAID-associated ulcers is a common clinical dilemma. High-dose famotidine in the healing and maintenance of NSAID-associated gastroduodenal ulceration was therefore evaluated.

METHODS

One hundred four patients with rheumatoid or osteoarthritis who had gastroduodenal ulceration received famotidine, 40 mg twice daily. Sixteen patients stopped and 88 continued their NSAID treatment. Ulcer healing was assessed endoscopically at 4 and 12 weeks. Seventy-eight NSAID users with healed ulcers were then randomized to receive 40 mg twice daily famotidine or placebo and underwent endoscopy at 4, 12, and 24 weeks.

RESULTS

Cumulative ulcer healing rates at 12 weeks were 89.0% (95% confidence interval [CI], 82.3%-95.7%) for patients who continued NSAID treatment and 100% (95% CI, 82.9%-100.0%) for those who stopped. The subsequent estimated cumulative gastroduodenal ulcer relapse over 6 months for NSAID users who took placebo was 53.5% (95% CI, 36.6%-70.3%). This was reduced to 26.0% (12.1%-39.9%) in patients taking famotidine (P = 0.011).

CONCLUSIONS

High-dose famotidine is effective ulcer healing therapy in patients who stop or continue NSAID treatment and significantly reduced the cumulative incidence of gastroduodenal ulcer recurrence compared with placebo when given as maintenance therapy.

Localization and up-regulation of mucin (MUC2) gene expression in human nasal biopsies of patients with cystic fibrosis

Using digoxigenin-UTP-labelled human HAM-1 (92 bp) or SMUC41 (850 bp) cRNA probes, the expression and localization of MUC2 gene transcripts were determined by in situ hybridization in human nasal tissues obtained as biopsies from 12 patients with cystic fibrosis (CF): all had been part of a gene therapy trial in which CFTR cDNA-liposome complexes had been delivered by topical application to eight and liposome alone to four as a placebo control. For comparison, there were nasal tissues taken at surgical resection from four non-CF subjects and a further four biopsies taken from normal healthy volunteer controls. Both SMUC41 and HAM-1 probes provided a strong signal. MUC2 mRNA transcripts were present in serous and mucous acini of submucosal glands, ciliated and basal cells of the surface epithelium, and occasional mononuclear inflammatory cells. The percentages (mean +/- SEM) of serous and mucous acini showing positivity for MUC2 gene expression in the four samples surgically resected from non-CF subjects were 25.4 +/- 5.6 and 26.7 +/- 3.3 per cent, respectively. Compared with the non-CF subjects, the mean percentage of acini showing MUC2 gene expression in the four placebo-treated CF subjects was significantly higher for serous (80.5 +/- 12.7 per cent; P < 0.05, t-test), but not for mucous acini (53.1 +/- 16.8 per cent; P = 0.38). In CF and non-CF groups, where present, MUC2 positivity was strongly expressed and constituted approximately 84 per cent of the cell area in serous acini, whereas it was less obvious and was confined to the perinuclear area of cells in mucous acini. A significantly greater proportion of the surface epithelium was positive for MUC2 mRNA transcripts in the CF subjects (89.0, +/- 1.4 per cent) than in the surgically resected tissues of the four non-CF subjects (19.4, +/- 4.0 per cent) (P = 0.02). In the eight CFTR-cDNA-treated subjects, there was an overall trend to reduction, but no statistically significant alteration of MUC2 gene expression. It is concluded that the MUC2 gene is expressed at three- to four-fold higher levels in CF nasal mucosa than in non-CF nasal tissue and that it is expressed in a variety of cells additional to submucosal mucus-secreting glands.

Prevention of heartburn relapse by low-dose famotidine: a test meal model for duration of symptom control

AIM

To establish whether patients taking famotidine 10 mg to treat an episode of heartburn were protected from a recurrence of symptoms after a subsequent test meal.

METHODS

Frequent heartburn sufferers (n = 366) were randomized to receive double blind treatment with famotidine 10 mg or 2 x 250 mg chewable alginate tablets within 30 min of a spontaneous episode of heartburn. After 4 h, patients with no or slight residual symptoms consumed a meal likely to induce heartburn. Over the next 4 h patients recorded the severity of heartburn and any consumption of 'rescue' antacids. At the end of this time they rated the global efficacy of their treatment in controlling meal-induced symptoms.

RESULTS

Study groups were well matched for all baseline characteristics. Of the 366 randomized patients, 276 took study medication and data from 269 patients (132 famotidine, 137 alginate) were analysed for efficacy. Compared to the alginate control group famotidine treated patients reported better global efficacy following the test meal (P < 0.001; relative odds for a more favourable response: 2.26 [95% CI: 1.45-3.53]). Fewer patients receiving famotidine resorted to antacid rescue (P = 0.038; relative odds for a more favourable response: 2.24 [95% CI: 1.04-4.79]) and peak heartburn was significantly less severe with famotidine treatment (P < 0.001: relative odds for a more favourable response: 2.90 [95% CI: 1.85-4.53]). Eleven famotidine-treated patients (8%) and 13 alginate patients (9%) reported adverse events.

CONCLUSION

Compared to patients receiving an alginate preparation, patients self medicating with famotidine 10 mg for heartburn are better protected against a recurrence of their symptoms when they next eat. This suggests that the duration of acid control (9 h) previously demonstrated with this dose translates into a similar duration of measurable symptom control during the day.

A transforming growth factor beta 1 receptor type II mutation in ulcerative colitis-associated neoplasms

BACKGROUND & AIMS

Numerous gastrointestinal tumors, notably sporadic and ulcerative colitis (UC)-associated colorectal carcinomas and dysplasias, gastric cancers, and esophageal carcinomas, manifest microsatellite instability. Recently, a transforming growth factor beta 1 type II receptor (TGF-beta 1RII) mutation in a coding microsatellite was described in colorectal carcinomas showing instability. One hundred thirty-eight human neoplasms (61 UC-associated, 35 gastric, 26 esophageal, and 16 sporadic colorectal) were evaluated for this TGF-beta 1RII mutation.

METHODS

Whether instability was present at other chromosomal loci in these lesions was determined. In lesions manifesting or lacking instability, the TGF-beta 1RII coding region polydeoxyadenine (poly A) microsatellite tract was polymerase chain reaction amplified with 32P-labeled deoxycytidine triphosphate. Polymerase chain reaction products were electrophoresed on denaturing gels and exposed to radiographic film.

RESULTS

Three of 18 UC specimens with instability at other chromosomal loci (17%) showed TGF-beta 1RII poly A tract mutation, including 2 cancers and 1 dysplasia; moreover, 2% of UC specimens without instability (1 of 43) (1 cancer), 81% of unstable sporadic colorectal cancers (13 of 16), and none of the 61 stable or unstable gastric or esophageal cancers contained TGF-beta 1RII mutations.

CONCLUSIONS

Mutational inactivation of the poly A microsatellite tract within TGF-beta 1RII occurs early and in a subset of unstable UC neoplasms and commonly in sporadic colorectal cancers but may be rare in unstable gastric and esophageal tumors.

Early and late effects of low-dose famotidine, ranitidine or placebo on pentagastrin-stimulated gastric acid secretion in man

BACKGROUND

There are no published comparative studies on the effect of low-dose H2-antagonists on pentagastrin-stimulated gastric acid secretion.

METHODS

Twenty-four healthy subjects were dosed with either famotidine 10 mg, ranitidine 75 mg or placebo in a balanced three-period cross-over design. The subjects were studied in groups of 12, simultaneously, under identical controlled environmental conditions. Gastric juice was aspirated in 15-min aliquots during sub-maximal (0.6 microgram.h/kg) intravenous pentagastrin stimulation in the third and fourth hours (early period) and the eighth and ninth hours (late period) after oral dosing. The hydrogen ion (H+) content of gastric juice was measured ex vivo, by titrating to pH7 known volumes of gastric aspirate against 0.1 M sodium hydroxide, using a versatile microprocessor-controlled auto-titration unit. Gastric acid output during the period of interest was calculated by adding the hydrogen ion content of 15-min aliquots collected during that period. The geometric mean of the cumulative pentagastrin-stimulated gastric acid output during the early and late periods was determined for the subjects dosed with either famotidine, ranitidine or placebo. Comparisons were performed by ANOVA.

RESULTS

During the early period (2-4 h post-dose), When the subjects were given placebo, mean gastric acid output was 46.6 mmol, decreasing by 76% to 11.3 mmol (P < 0.001) when treated with famotidine and by 76% to 11.1 mmol (P < 0.001) when treated with ranitidine. During the late period (7-9 h post-dose), when the subjects were dosed with placebo, mean gastric acid output was 41.2 mmol, decreasing by 38% to 25.7 mmol (P < 0.001) when treated with famotidine and by 27% to 30.0 mmol (P = 0.007) when treated with ranitidine. The difference between the inhibitory effects of famotidine and ranitidine on gastric acid output were non-significant during either period.

CONCLUSIONS

Low-dose famotidine and ranitidine, intended for over-the-counter use, inhibit stimulated gastric acid secretion profoundly in the third and fourth hours after an oral dose. Modest effects are still detectable up to 9 h after dosing.

Low-dose famotidine and ranitidine as single post-prandial doses: a three-period placebo-controlled comparative trial

BACKGROUND

Low-dose H2-receptor antagonists are available without prescription for the self-medication of dyspepsia.

METHODS

To investigate the relative abilities of low doses of famotidine and ranitidine to raise intragastric pH after a single post-prandial evening dose, 25 healthy volunteers completed a three-period cross-over trial of famotidine 10 mg, ranitidine elixir 75 mg and placebo. A standard meal was given at 18.30 h and drug or placebo at 19.30 h to subjects fasted for 5.5 h. Intragastric pH was recorded with nasogastric electrodes from 18.00 to 07.30 h by GastrograpH II recorder.

RESULTS

The geometric mean area under the pH-time curve for the 5-9 h post-dose period was 1.49 pH units/h following placebo, 3.43 pH units/h following famotidine 10 mg (agent/placebo ratio 2.3; P < 0.001, ANOVA) and 2.6 pH units/h following ranitidine 75 mg (1.75; P < 0.001). The geometric mean area under the pH-time curve ratio of famotidine 10 mg to ranitidine 75 mg was 1.32 (P < 0.016). Median pH over the 5-9 h period was 1.1 following placebo, 2.7 following famotidine 10 mg (P < 0.05 by comparison with placebo) and 1.9 following ranitidine 75 mg (P < 0.05); comparison of median pH showed no significant difference between the active drugs. The percentage of pH values greater than 3.0 for the period 0-12 h post-dose was 9.7% following placebo, 30.0% following famotidine 10 mg (P < 0.05) and 24.9% following ranitidine 75 mg (P < 0.05); there was no significant difference between the active drugs.

CONCLUSIONS

We conclude that both famotidine 10 mg and ranitidine 75 mg significantly raise intragastric pH when given as single post-prandial doses. Famotidine 10 mg may have a greater effect than ranitidine elixir 75 mg over the 5-9-h period after dosing.

Alterations of transforming growth factor-beta 1 receptor type II occur in ulcerative colitis-associated carcinomas, sporadic colorectal neoplasms, and esophageal carcinomas, but not in gastric neoplasms

BACKGROUND & AIMS

Gastric cancers, sporadic colorectal cancers, and ulcerative colitis (UC)-associated colorectal carcinomas and dysplasias manifest microsatellite instability (MI); however, esophageal carcinomas rarely exhibit MI. Recently, a transforming growth factor-beta 1 type II receptor (TGF-beta 1RII) mutation in a coding microsatellite was described in primary colorectal carcinomas demonstrating MI. No previous studies of TGF-beta 1RII have addressed mechanisms of inactivation other than MI in human tumors; furthermore, MI-negative tumors have not been examined for TGF-beta 1RII mutation. We evaluated 138 primary human neoplasms for mutation in the poly-A microsatellite tract of TGF-beta 1RII. Additionally, a group of esophageal tumors was evaluated for the expression of TGF-beta 1RII messenger RNA (mRNA).

METHODS

First, we determined whether MI was present at other chromosomal loci in these lesions. The poly-deoxyadenine (poly-A) microsatellite tract within the TGF-beta 1RII coding region was then PCR-amplified. In a group of MI-negative esophageal tumors, RT-PCR was performed to determine the expression of TGF-beta 1RII mRNA.

RESULTS

Among 17 MI+ UC specimens, 3 (18%) demonstrated TGF-beta 1RII poly-A tract mutation (2 cancers and 1 dysplasia), while 2 (4%) of 44 MI-negative UC specimens (1 dysplasia and 1 tumor), and 13 (81%) of 16 MI+ sporadic colorectal cancers, contained TGF-beta 1RII poly-A mutation. No gastric or esophageal tumors contained TGF-beta 1RII mutation. Among 21 MI-negative esophageal carcinomas. 6 cases (28.5%) had TGF-beta 1RII transcripts that were low or undetectable by RT-PCR.

CONCLUSIONS

Mutation within the poly-A microsatellite tract of TGF-beta 1RII occurs early in a subset of UC-neoplasms and commonly in sporadic colorectal cancers, but may be rare in MI+ gastric tumors. Diminished expression of TGF-beta 1RII mRNA in esophageal tumors suggests that mechanisms of inactivation in this gene other than MI play a role in esophageal carcinogenesis.

Famotidine for the prevention of gastric and duodenal ulcers caused by nonsteroidal antiinflammatory drugs

BACKGROUND

Acid suppression with famotidine, a histamine H2-receptor antagonist, provides protection against gastric injury in normal subjects receiving short courses of aspirin or naproxen. The efficacy of famotidine in preventing peptic ulcers in patients receiving long-term therapy with nonsteroidal antiinflammatory drugs (NSAIDs) is not known.

METHODS

We studied the efficacy of two doses of famotidine (20 mg and 40 mg, each given orally twice daily), as compared with placebo, in preventing peptic ulcers in 285 patients without peptic ulcers who were receiving long-term NSAID therapy for rheumatoid arthritis (82 percent) or osteoarthritis (18 percent). The patients were evaluated clinically and by endoscopy at base line and after 4, 12, and 24 weeks of treatment. The evaluators were unaware of the treatment assignment. The primary end point was the cumulative incidence of gastric or duodenal ulceration at 24 weeks.

RESULTS

The cumulative incidence of gastric ulcers was 20 percent in the placebo group, 13 percent in the group of patients receiving 20 mg of famotidine twice daily (P = 0.24 for the comparison with placebo), and 8 percent in the group receiving 40 mg of famotidine twice daily (P = 0.03 for the comparison with placebo). The proportion of patients in whom duodenal ulcers developed was significantly lower with both doses of famotidine than with placebo (13 percent in the placebo group, 4 percent in the low-dose famotidine group [P = 0.04], and 2 percent in the high-dose famotidine group [P = 0.01]). Both doses of famotidine were well tolerated.

CONCLUSIONS

Treatment with high-dose famotidine significantly reduces the cumulative incidence of both gastric and duodenal ulcers in patients with arthritis receiving long-term NSAID therapy.

Comparison of cyclic and linear analogs of vasoactive intestinal peptide

A series of i-->i + 4 side-chain to side-chain lactam analogs of vasoactive intestinal peptide has been prepared in order to study the effect of cyclization on biological activity. In vitro, on guinea pig tracheal smooth muscle and on human bronchial tissue, approximately half of the cyclic analogs showed increased potency and half were decreased over the linear analogs. Several cyclic compounds were between 10- and 20-fold more potent and one was 290-fold more potent than the linear species. In vivo, in guinea pigs, the cyclic compounds showed increased potency by up to 70-fold and significantly enhanced duration of action as compared to linear compounds.

Propofol reduces neuronal transmission damage and attenuates the changes in calcium, potassium, and sodium during hyperthermic anoxia in the rat hippocampal slice

BACKGROUND

Propofol reduces cerebral blood flow, cerebral metabolic rate for oxygen, and intracranial pressure and is being increasingly used in neuroanesthesia. In vivo studies have yielded conflicting results on its ability to protect against ischemic brain damage. In the current study, an in vitro model was used to examine the mechanism of propofol's action on anoxic neuronal transmission damage.

METHODS

A presynaptic pathway was stimulated in the rat hippocampal slice to elicit a postsynaptic population spike in the CA1 region. The effects of propofol (20 micrograms/ml), its solvent intralipid or no drug, on the population spike before, during, and 60 min after anoxia at 37 degrees C or 39 degrees C were examined. Intracellular adenosine triphosphate (ATP), Na, and K were measured in dissected CA1 regions at 37 degrees C and 39 degrees C after 5 min of anoxia; 45Ca influx was measured after 10 min of anoxia.

RESULTS

Propofol did not improve recovery after 5, 6, or 7 min of anoxia at 37 degrees C. Recovery of the population spike after 6 min of anoxia at 37 degrees C was 62 +/- 11% with propofol, 35 +/- 15% with intralipid, and 44 +/- 10% in untreated tissue (NS). After 5 min of anoxia at 39 degrees C, there was significantly better recovery of the population spike with propofol (76 +/- 12%) than with intralipid (11 +/- 6%) or no drug (13; +/- 5%). Propofol, but not intralipid, reduced the population spike amplitude before anoxia. At 37 degrees C, anoxia caused significant changes in ATP (62% of normoxic concentration), Ca (115%), Na (138%), and K (68%). Both propofol and intralipid significantly attenuated the changes in ATP (78% and 82% of normoxic concentration) and Ca (104% and 103%). Na changes were attenuated by propofol (95%) but not intralipid; K concentration was not affected by either drug. At 39 degrees C, for most parameters, anoxia caused more marked changes: ATP was 23% of normoxic concentration, Ca 116%, Na 185%, and K 48%. Both propofol and intralipid attenuated the decrease in ATP (56% of normoxic); propofol, but not intralipid, significantly attenuated the changes in Ca (100%), Na (141%), and K (63%).

CONCLUSIONS

Propofol improved electrophysiologic recovery from anoxia during hyperthermia but not normothermia. At 37 degrees C propofol attenuated the changes in ATP, Na, and Ca, however, this did not result in improved recovery. At 39 degrees C the changes in ATP, Na, and K caused by anoxia were greater than at 37 degrees C; this could explain why electrophysiologic damage was worsened. Improved recovery with propofol at 39 degrees C may be explained by its attenuation of the changes in Ca, Na, and K at this temperature. The decrease in ATP was attenuated by both propofol and intralipid and therefore cannot explain the improved recovery.

Structure-activity studies on the vasoactive intestinal peptide pharmacophore. 1. Analogs of tyrosine

From previous work, the primary functional groups, i.e. side chains, of the vasoactive intestinal peptide which are responsible for interaction with the VIP receptor have been identified. One of these sites, the side chain of tyrosine22 is essential for high receptor affinity. The present work aims to examine this site in greater detail. Several Boc-substituted-phenylalanine derivatives were prepared and incorporated into VIP analogs as replacement for tyrosine22. These analogs, of the form Ac-[Lys12,Nle17,X22,Val26,Thr28]-VIP, were assayed as smooth muscle relaxants and found to be full agonists of native VIP. Most of the analogs, however, proved to be less potent than the parent analog by up to 300-fold. A few analogs, all possessing electron-donating substituents, retained nearly full potency. Two compounds, 3-F,4-OH-Phe, 42 and 3-OCH3,4-OH-Phe, 43, were found to be 1.5- and 3.4-fold more potent than the parent compound, which equates to being 8.9- and 20-fold more potent than native VIP. Compound 43 was also found to be active as a bronchodilator in vivo in guinea pigs, with slightly over 2-fold enhanced potency and a significantly longer duration of action (> 20 min) when compared to the parent compound (5 min). The physical characteristics of the various substituents and their effect on biological activity are discussed with a brief analysis by QSAR techniques.

Low dose famotidine in the prevention of sleep disturbance caused by heartburn after an evening meal

AIM

To determine whether, in a susceptible population, dosing with 10 mg famotidine 1 h before an evening meal could decrease the interference with sleep caused by heartburn.

METHODS

Patients with a history of frequent heartburn (n = 309) were randomized to receive 10 mg famotidine or placebo 1 h before an evening meal likely to induce symptoms. Patients assessed the efficacy of the treatment in preventing heartburn after the meal, at bedtime and during the night. The number of awakenings due to heartburn and the consumption of antacid tablets taken to alleviate symptoms were also recorded.

RESULTS

Treatment groups were well matched and data from 302 patients were available for analysis. Compared to placebo, famotidine treated patients had: less heartburn after the meal (P < 0.0001 mean global scores), less interference with getting to sleep (P = 0.0156 mean global scores), fewer awakenings (P = 0.0001 difference in mean number) and better control of heartburn during the night (P < 0.0001 mean global scores). They were also almost three times less likely to need antacid treatment than the placebo group during the night (relative odds for no antacid 2.78 (95% CI: 1.29-5.96). Only four patients in each group suffered adverse events.

CONCLUSION

Taking a 10 mg dose of famotidine 1 h before an evening meal appears to be a successful and well tolerated strategy for preventing post-prandial heartburn and avoiding the associated interference with sleep.

Frequent loss of heterozygosity on chromosome 9 in adenocarcinoma and squamous cell carcinoma of the esophagus

Loss of heterozygosity (LOH) affecting chromosome 9p has been shown to occur frequently in head and neck cancer, glioma, mesothelioma, melanoma, lung cancer, and numerous other tumor types. Chromosome 9p is therefore presumed to contain a tumor suppressor gene or genes. Since esophageal cancer shares characteristics with some of the above tumor types, we performed a detailed examination of 60 patients with squamous cell carcinoma or adenocarcinoma of the esophagus for LOH at loci D9S162, IFNA, D9S171, D9S126, D9S104, D9S165, and D9S163. Multiplex polymerase chain reactions were performed with the inclusion of one radiolabeled nucleotide, and products were electrophoresed on denaturing polyacrylamide gels. Thirty-six of the 60 patients (60%) exhibited LOH at one or more loci on chromosome 9p. Eight of 17 patients (47%) with adenocarcinoma manifested LOH, while 28 of 43 (65%) with squamous cell carcinoma showed LOH. LOH was most frequent at loci D9S171 (19 of 23, or 83%) and D9S165 (24 of 32, or 75%). These data support the hypothesis that a tumor suppressor gene or genes located on this portion of chromosome 9p exert(s) an effect on esophageal cancer development.

Microsatellite instability occurs frequently and in both diploid and aneuploid cell populations of Barrett's-associated esophageal adenocarcinomas

Alterations of microsatellites consisting of extra or missing copies of these sequences occur at relatively high frequencies in sporadic and hereditary colorectal adenocarcinomas, gastric and pancreatic cancers, and at lower frequencies in endometrial, bladder, ovarian, and other carcinomas. We determined the prevalence of microsatellite instability in esophageal adenocarcinoma, Barrett's esophagus, and squamous cell carcinoma of the esophagus. Assays were performed on 105 patients, including 28 subjects with Barrett's metaplasia, 36 with Barrett's-associated adenocarcinoma, and 42 with primary esophageal squamous cell carcinoma. Flow cytometric nuclear sorting based on DNA content was performed on 25 of the adenocarcinomas prior to DNA extraction. Specimens from 11 of the 106 patients (10%) showed instability at 1 or more chromosomal loci. Instability was seen in 2 of 28 patients (7%) with Barrett's metaplasia alone, in 8 of 36 (22%) with adenocarcinoma, and in 1 of 42 (2%) with squamous cell carcinoma. Among the 25 flow cytometrically sorted adenocarcinomas, instability occurred in 8 (32%); sorted diploid nuclei from these tumors showed instability in 4 of 8 cases (50%). These data indicate that microsatellite instability occurs frequently in Barrett's-associated esophageal adenocarcinoma. They also suggest that in esophageal adenocarcinomas, microsatellite instability can develop as an early event in metaplasia and in diploid tumor cells, before aneuploidy occurs.

Structure-activity studies of vasoactive intestinal peptide (VIP): cyclic disulfide analogs

Analogs of vasoactive intestinal peptide with cysteine residues incorporated at selected sites within the sequence were prepared by solid phase methods, oxidized to the corresponding cyclic disulfides and purified to homogeneity by preparative HPLC. The cyclic compounds were assayed as smooth muscle relaxants on isolated guinea pig trachea, as bronchodilators in vivo in guinea pigs, and for binding to VIP receptors in guinea pig lung membranes. Of the analogs prepared at the N-terminus, one compound, Ac-[D-Cys6,D-Cys11,Lys12,Nle17,Val26,Th r28]-VIP, was found to be a full agonist with slightly more than one tenth the potency of native VIP. Most other cyclic analogs in the N-terminal region were found to be inactive. A second analog, Ac-[Lys12,Cys17,Val26,Cys28]-VIP, was also found to be a full agonist with potency about one third that of native VIP. Furthermore, this compound was active as a bronchodilator in vivo in guinea pig, but with somewhat diminished potency as compared to native VIP. Strikingly, this cyclic compound was found to have significantly longer duration of action (> 40 min) when compared to an analogous acyclic compound (5 min). The conformational restrictions imposed by formation of the cyclic ring structures may have stabilized the molecule to degradation, thus enhancing the effective duration of action. Analysis of this series of cyclic analogs has also yielded information about the requirements for the receptor-active conformation of VIP.

Continuous intravenous famotidine for haemorrhage from peptic ulcer

Peptic ulcer bleeding often stops spontaneously but rebleeding may be catastrophic. Emergency surgery carries risks so safe medical therapies are needed. Since platelet function and plasma coagulation are both pH sensitive and since pepsin lyses clot at low pH the maintenance of gastric pH close to neutrality might influence rebleeding rates. Previous trials with H2 antagonists have been inadequate although a 1985 meta-analysis did support an important clinical effect. We report here a large multicentre trial of famotidine in ulcer bleeding. 1005 patients admitted to one of sixty-seven hospitals in the UK or Eire with haemorrhage from peptic ulcer with endoscopic signs of oozing, black slough, fresh clot or visible vessel were randomly allocated to famotidine (10 mg bolus followed by 3.2 mg/h intravenously) or matching placebo for 72 h. This famotidine regimen had previously been shown to maintain pH near 7 in such patients. 497 patients received famotidine and 508 placebo. The treatment groups were similar in respect of age, sex, ulcer site, and signs and severity of bleeding. Case fatality (6.2% famotidine vs 5.0% placebo), rebleeding (23.9% vs 25.5% placebo), and surgery (15.5% vs 17.1% placebo) rates were not significantly different between the two groups. This trial suggests that potent inhibition of gastric secretion does not influence the natural history of peptic ulcer haemorrhage.

Pharmacokinetics of famotidine in normal subjects and in patients with chronic liver disease

The pharmacokinetics of famotidine were studied in seven healthy control subjects and in 14 patients with cirrhosis, following single oral and intravenous 20-mg dose administration, and after seven daily doses of 40 mg. Following intravenous (i.v.) administration, the mean (range) total plasma clearance values were not significantly different in the patients with compensated cirrhosis (n = 7), 337 (241-576) ml/min or in the patients with decompensated cirrhosis (n = 7), 270 (120-408) ml/min compared with the control group, 370 (154-612) ml/min. The mean half-life in the compensated cirrhotics, 2.86 (1.87-4.98) h, was similar to that in the control group 2.91 (1.86-6.03) h, but it was insignificantly prolonged in the decompensated cirrhotics 3.35 (2.00-5.77) h. The mean, maximum, plasma famotidine concentrations after single oral doses were comparable between the groups but there was considerable inter-subject variability, with individual values ranging from 17 to 139 ng/ml. Peak plasma concentrations were reached within 2-3 h, although more variability was observed among patients with decompensated cirrhosis. The mean systemic availability of the drug, estimated from urinary recovery, was 0.39 (0.15-0.64) in the healthy controls, 0.35 (0.14-0.51) in the patients with compensated cirrhosis and 0.38 (0.13-0.77) in the patients with decompensated cirrhosis. No significant increases were observed in plasma trough famotidine concentrations following multiple oral dosing in any of the subjects, and the kinetic variables after the seventh dose were not significantly different from those following the single oral dose. No significant changes were observed in psychometric performance in control subjects or in patients between the pre-study day and day seven of the multiple oral dose phase.

Single night-time doses of 40 mg famotidine or 800 mg cimetidine in the treatment of duodenal ulcer

Famotidine (40 mg) and 800 mg cimetidine as single night-time doses were compared in a randomized, double-blind, multicentre study of acute treatment for duodenal ulceration. Fifteen centres recruited 304 patients into the study. Of these, 274 were included for analysis, with 136 receiving famotidine and 138 receiving cimetidine. After 4 weeks, 75% of the patients who received famotidine and 77% of the patients who received cimetidine were healed. At 6 weeks the cumulative healing rates were 91% with famotidine and 87% with cimetidine. Differences between the groups were not significant at 4 or 6 weeks. No significant difference in healing rates between smokers and non-smokers was found. Day and night pain resolved rapidly in both groups. Both treatments were well-tolerated; adverse events were reported in 17 patients on famotidine and 18 on cimetidine, with headache the most frequent event in both groups. Famotidine is effective and well-tolerated in the short-term treatment of duodenal ulcer.

Prophylaxis against acid aspiration syndrome. Single oral dose of H2-antagonist on the evening before elective surgery

We have compared famotidine 40 mg, ranitidine 300 mg and placebo given in a single oral dose at 2200 hours as the sole means of prophylaxis in 286 patients who underwent elective surgery the following day. Standardised premedication was administered and anaesthesia induced. Gastric contents were aspirated by nasogastric suction and the pH and volume measured. Median values of pH after famotidine, ranitidine and placebo were 6.17, 6.74 and 2.45 respectively; median aspirate volumes were 8, 8 and 10 ml respectively. The proportions of patients considered 'not at risk' (pH greater than 2.5) were 90% after famotidine, 91% after ranitidine and 52% after placebo. We conclude that the administration of a potent H2-antagonist in a single oral dose at night offers a convenient routine means of providing extensive prophylactic cover in patients scheduled to undergo elective surgery the following day.

The aesthetics of colour

A paired comparison experiment is described in which preferences for Munsell colour patches were elicited from 54 subjects. Value, chroma, and hue preferences were examined separately, Individuals differed in their preferences for value and chroma, and also for hue. There were also sex differences in preference. Overall the majority of subjects showed a preference for blue hues and dislike for yellow hues, thus demonstrating a continuity between animal and human colour aesthetics.

Furosemide facilitates recovery of evoked twitch response after pancuronium

Two groups consisting of 10 A.S.A. class I-II neurosurgical patients each were studied to determine whether patients require greater quantities of pancuronium to maintain paralysis after having been given furosemide, 1 mg/kg. After a standardized barbiturate, narcotic and nitrous oxide induction of anesthesia, pancuronium was given intravenously until twitch response was suppressed by 95%. The study group received in addition furosemide, 1 mg/kg, 10 minutes prior to induction of anesthesia. Mean recovery time from 95% to 50% twitch suppression was 21.8 minutes in the control group and 14.7 minutes in the study group. Urinary output was significantly greater (13.5 vs 674 ml) and serum potassium levels lower (4.05 vs 3.85 meq/L) in the study group during recovery of twitch response. Furosemide, 1 mg/kg, facilitates recovery of evoked twitch response after pancuronium.