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Biomedical subjects

J D Gardner

Publications and source records attributed to J D Gardner.

At least 127 records · Page 7Linked to original sources
PubMed1987

Cimetidine pharmacokinetics in patients with Zollinger-Ellison syndrome.

Although most patients with Zollinger-Ellison syndrome can be effectively treated with histamine H2-receptor antagonists, many patients require large doses of drug to inhibit gastric acid secretion adequately. The purpose of the present study was to compare the pharmacokinetics of a 1200-mg oral dose of cimetidine in 9 patients with Zollinger-Ellison syndrome requiring more than 2.4 g/day of cimetidine with 5 age-matched normal volunteers receiving intravenous pentagastrin infusions. Poor responsiveness to cimetidine in patients with Zollinger-Ellison syndrome has several different causes. The concentration of cimetidine in the blood required to inhibit gastric acid secretion by 50% was markedly increased in 3 of the patients with Zollinger-Ellison syndrome, suggesting parietal cell resistance. One patient showed a substantial decrease in cimetidine absorption and 4 patients had delayed cimetidine absorption. Thus 7 of the 9 patients with Zollinger-Ellison syndrome who required more than 2.4 g/day of cimetidine to inhibit gastric acid secretion had abnormal cimetidine pharmacokinetics.

Adult↗
PubMed1987

Prospective study of the ability of computed axial tomography to localize gastrinomas in patients with Zollinger-Ellison syndrome.

The ability of routine computed tomography (CT) performed with oral and intravenous contrast to localize gastrinomas in 61 consecutive patients with Zollinger-Ellison syndrome was evaluated prospectively. The results of CT scanning were subsequently evaluated in all patients by either surgery, autopsy, or percutaneous biopsy. Thirteen of 14 patients with CT scans positive for hepatic metastases and 5 of 13 patients with CT scans negative for hepatic metastases were found to have gastrinoma in the liver. For gastrinoma metastatic to the liver, CT scanning had a specificity of 98%, a sensitivity of 72%, a positive predictive value of 93%, and a negative predictive value of 90%. Twenty-two of 23 patients with positive extrahepatic CT scans and 15 of 33 patients with negative extrahepatic CT scans were found to have extrahepatic gastrinomas. For extrahepatic gastrinoma, CT scanning had a specificity of 95%, a sensitivity of 59%, a positive predictive value of 96%, and a negative predictive value of 54%. The ability of CT scan to detect gastrinomas both in the liver and extrahepatically was directly related to tumor size, detecting 0% of tumors less than 1 cm and 83%-95% of tumors greater than 3 cm. The location of the extrahepatic gastrinoma was also an important determinant in that approximately 80% of pancreatic gastrinomas but only 35% of extrapancreatic gastrinomas were detected. The present results indicate that because of its convenience and accuracy, CT scanning with oral and intravenous contrast material should be the initial procedure to evaluate the extent of gastrinoma. A positive CT scan is almost always correct; therefore, a CT scan detecting metastatic gastrinoma to the liver would avoid unnecessary surgery and, if positive for extrahepatic gastrinoma, would assist the surgeon in finding the gastrinoma. A negative CT is less reliable; therefore, patients should undergo other localizing studies before exploratory laparotomy.

Biopsy↗
PubMed1987

Role of selective angiography in the management of patients with Zollinger-Ellison syndrome.

To determine the ability of selective abdominal angiography to localize gastrinoma in patients with Zollinger-Ellison syndrome, selective angiography was performed in 70 consecutive patients and the results were assessed prospectively by either surgery, autopsy, or percutaneous biopsy. In addition, to define the role of angiography in the management of patients with gastrinoma, we compared the results of angiography with those of computed tomography (CT) scanning in 58 patients who underwent both tests. For gastrinoma in the liver, angiography had a specificity of 100% and a sensitivity of 86% with a positive predictive value of 100% and a negative predictive value of 94%. For extrahepatic gastrinoma, angiography had a specificity of 94% and a sensitivity of 68%, a positive predictive value of 97% and a negative predictive value of 53%. Comparison of CT scanning and angiography demonstrated that for hepatic tumor CT demonstrated 72% and angiography 89% of tumors, and the combination detected all tumors with no false-positive results. Outside the liver, CT scanning detected 57%, angiography 70%, and the combination 73% of tumors with a false-positive rate of 7%. These results indicate that if a CT scan is performed first, then the addition of selective angiography will detect a further 28% of hepatic tumors and a further 16% of extrahepatic tumors, but that 24% of extrahepatic tumors will still be missed. Angiography is a useful adjunct to CT particularly in patients in whom surgery is contemplated.

Abdomen↗
PubMed1987

Famotidine: effective treatment of Zollinger-Ellison syndrome.

The ability of famotidine to control gastric acid hypersecretion in 32 patients with Zollinger-Ellison syndrome was compared to that of cimetidine or ranitidine. Equipotent doses of each drug were determined in nine patients and famotidine was nine times more potent than ranitidine and 32 times as potent as cimetidine. Famotidine had a 30% longer duration of action than either ranitidine or cimetidine. The 32 patients were treated with famotidine for a mean follow-up of 10.5 months. No hematologic, biochemical, or clinical toxicity occurred. Famotidine appears to be the histamine H2-receptor antagonist of choice in the treatment of Zollinger-Ellison syndrome.

Adult↗
PubMed1987

Role of sulfate ester in influencing biologic activity of cholecystokinin-related peptides.

In dispersed acini from guinea pig, mouse, or rat pancreas cholecystokinin-(27-33) is a full agonist, and removing the sulfate ester from the tyrosine residue in position 27 caused a 100- to 300-fold decrease in potency with no change in efficacy. In dispersed acini from mouse or rat pancreas, cholecystokinin-(27-32)-NH2 is a partial agonist, and removing the sulfate ester from the tyrosine in position 27 abolished the efficacy. The desulfated peptide was able, however, to interact with CCK receptors with a potency that was threefold less than that of cholecystokinin-(27-32)-NH2 and therefore functioned as a cholecystokinin receptor antagonist. In dispersed acini from guinea pig pancreas cholecystokinin-(27-32)-NH2 is a cholecystokinin receptor antagonist. Removing the sulfate ester from the tyrosine residue in position 27 of cholecystokinin(27-32)-NH2 caused a fourfold decrease in potency but did not abolish the ability of the peptide to interact with cholecystokinin receptors; therefore, desulfated cholecystokinin-(27-32)-NH2 functioned as a cholecystokinin receptor antagonist.

Amylases↗
PubMed1987

Characterization of receptors for VIP on pancreatic acinar cell plasma membranes using covalent cross-linking.

Vasoactive intestinal peptide (VIP) receptors on guinea pig pancreatic acini differ from those on all other tissues in containing a high-affinity VIP receptor and a low-affinity VIP receptor that has a high affinity for secretin. To characterize the molecular components of these receptors, 125I-VIP was covalently cross-linked to these receptors by four different cross-linking agents: disuccinimidyl suberate, ethylene glycol bis (succinimidyl succinate), dithiobis (succinimidylpropionate), and m-maleimidobenzoyl N-hydroxysuccinimide ester. Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis demonstrated a single major polypeptide band of Mr 45,000 and a minor polypeptide band of Mr 30,000 were cross-linked to 125I-VIP. Covalent cross-linking only occurred when a cross-linking agent was added, was inhibited by GTP, was inhibited by VIP receptor agonists or antagonists that interact with VIP receptors, and not by other pancreatic secretagogues that interact with different receptors. For inhibiting both cross-linking and binding of 125I-VIP to the major polypeptide Mr 45,000 and the minor polypeptide Mr 30,000 components, the relative potencies were VIP greater than helodermin greater than rat growth hormone releasing factor greater than peptide histidine isoleucine greater than secretin. The apparent molecular weight of the cross-linked polypeptides were unchanged by dithiothreitol. Thus the high-affinity VIP receptor on pancreatic acinar cell membranes consists of a single major polypeptide of Mr 45,000, and this polypeptide is not a subunit of a larger disulfide-linked structure. Furthermore, either the low-affinity VIP/secretin-preferring receptor was not covalently cross-linked under the experimental conditions or it consists of a major polypeptide with the same molecular weight as the high-affinity VIP receptor.

Animals↗
PubMed1987

[D-Phe12]bombesin analogues: a new class of bombesin receptor antagonists.

Previous attempts to develop analogues of bombesin that function as specific receptor antagonists have been unsuccessful. Alteration of the histidine in luteinizing hormone releasing factor has resulted in analogues that function as competitive antagonists. In the present study we have used a similar strategy and altered the histidine in bombesin. [D-Phe12]bombesin, [D-Phe12,Leu14]bombesin, and [Tyr4,D-Phe12]bombesin did not stimulate amylase release from guinea pig pancreatic acini when present alone, but each analogue inhibited bombesin-stimulated secretion. For each analogue, detectable inhibition occurred at 1 microM and half-maximal inhibition at 4 microM. Each analogue inhibited amylase release by bombesin and other agonists that stimulate secretion by interacting with bombesin receptors. The analogues of bombesin did not alter stimulation by substance P or other agonists that interact with other receptors. The inhibition of the action of bombesin was competitive with Schild plots having slopes of 1.0. Each analogue also inhibited binding of 125I-labeled [Tyr4]bombesin but not 125I-labeled substance P. These results demonstrate that [D-Phe12] analogues of bombesin function as bombesin receptor antagonists and are the only bombesin receptor antagonists that interact only with the bombesin receptor. Because of their specificity, these analogues may prove useful for defining the role of bombesin in various physiological or pathological processes.

Amino Acid Sequence↗
PubMed1987

Characterization of gastrin receptors on guinea pig pancreatic acini.

Recent studies have demonstrated gastrin receptors in some pancreatic tumors and that gastrin is a potent stimulant of pancreatic Na+-H+ exchange. In the present study we used 125I-labeled gastrin (125I-gastrin) to characterize gastrin receptors on guinea pig pancreatic acini. Binding of 125I-gastrin was temperature dependent, saturable, and specific for gastrin-related peptides. Analysis demonstrated a single class of receptors with high affinity for gastrin (Kd = 1.5 nM) and a binding capacity of 1 fmol/mg protein. Binding of 125I-gastrin was inhibited with the following relative potencies (Kd): cholecystokinin octapeptide (CCK-8) (0.35 nM) greater than gastrin-17-I = gastrin-34-I (1.5 nM) greater than pentagastrin (7 nM) greater than desulfated [des(SO3)]CCK-8 (28 nM) greater than CCK-4 (508 nM) and by the receptor antagonists CBZ-CCK-27-32-NH2 (3.5 microM) greater than proglumide analogue 10 (30 microM) greater than asperlicin (265 microM) greater than Bt2-guanosine 3',5'-cyclic monophosphate (828 micron). In contrast, for both stimulation of enzyme secretion and inhibition of binding of 125I-CCK-8 the relative potencies were CCK-8 much greater than des(SO3)CCK-8 greater than gastrin-17-I = gastrin-34-I greater than pentagastrin greater than CCK-4. For each receptor antagonist the dose-inhibition curve for gastrin-stimulated amylase release was superimpossible with that for CCK-8-stimulated amylase release. Gastrin-17-I at concentrations less than 0.1 microM did not potentiate carbachol or vasoactive intestinal peptide-stimulated amylase secretion and did not affect basal or stimulated adenosine 3',5'-cyclic monophosphate or 45Ca outflux.(ABSTRACT TRUNCATED AT 250 WORDS)

Amylases↗
PubMed1987

Effect of parathyroidectomy in patients with hyperparathyroidism, Zollinger-Ellison syndrome, and multiple endocrine neoplasia type I: a prospective study.

This study evaluates prospectively the effect of parathyroidectomy on basal acid output (BAO), maximal acid output (MAO), fasting serum gastrin, secretin-stimulated serum gastrin, and sensitivity to antisecretory medication in 10 consecutive patients with primary hyperparathyroidism (PHP), Zollinger-Ellison syndrome (ZES), and multiple endocrine neoplasia type I (MEN-I). After parathyroidectomy, 9 of 10 patients remained normocalcemic, and each had a lower BAO; 6 of 9 no longer had gastric acid hypersecretion (less than 15 mEq/hr). Seven of 9 normocalcemic patients had a lower MAO, and a decrease in fasting serum gastrin. Two patients showed no evidence of ZES, a normal BAO, normal fasting serum gastrin concentration, and a negative secretin response after parathyroidectomy. Parathyroidectomy also reduced the dose of histamine H2-receptor antagonist required to control gastric acid secretion in 60% of patients. After successful parathyroidectomy three patients were studied for drug sensitivity, and each had greater acid inhibition with a given dose of histamine H2-receptor antagonist than preoperatively. One patient remained hypercalcemic after surgery and had no change in BAO, MAO, or gastrin. All patients with postoperative normocalcemia will have a lower BAO, 80% a lower MAO, 80% a decreased fasting serum gastrin, and 33% a negative secretin test. Antisecretory medication dose can be reduced because patients have reduced BAO and increased sensitivity to histamine H2-receptor antagonist. The study supports parathyroidectomy as the initial surgical procedure of choice in patients with PHP, ZES, and MEN-I.

Adult↗
PubMed1986

Famotidine in the therapy of gastric hypersecretory states.

The histamine (H2)-receptor antagonist famotidine was compared with ranitidine and cimetidine in its ability to control gastric acid hypersecretion in 33 patients with gastric hypersecretory states (32 patients with Zollinger-Ellison syndrome and one patient with idiopathic hypersecretion). Equipotent doses of each drug were determined in nine patients and used to determine relative onset of action, duration of action, and potency. Each drug had a similar time course of onset with a maximal effect at three to four hours after oral ingestion. The duration of action of famotidine was 30 percent longer than that of either cimetidine or ranitidine. In terms of relative potency, famotidine was nine times more potent than ranitidine and 32 times more potent than cimetidine. Thirty-two patients underwent long-term famotidine treatment for up to 34 months (mean, 10 months) with a duration in 21 patients of at least six months, in nine patients of at least 12 months, and in six patients of at least 24 months. The mean daily maintenance dose with famotidine was 0.33 g per day (range, 0.05 to 0.8 g). Prior to famotidine therapy, 27 patients were taking ranitidine and the mean daily dose required was 2.3 g per day (range, 0.6 to 5.4 g), whereas six patients were taking cimetidine and the mean daily dose was 4.6 g per day (range, 1.2 to 9.0 g). Fourteen of the 32 patients required an anticholinergic agent in addition to ranitidine or cimetidine to maintain control, whereas only five patients required an anticholinergic agent with famotidine. Gastric acid hypersecretion was controlled in seven patients with less frequent dosing with famotidine than with cimetidine or ranitidine. Long-term treatment with famotidine was not associated with any hematologic or biochemical toxicity or clinical side effects. These results demonstrate that famotidine has a similar onset of action to other H2-receptor antagonists but has a 30 percent longer duration of action and is nine times more potent than ranitidine and 32 times more potent than cimetidine. Famotidine is safe and highly effective in the long-term treatment of gastric hypersecretory states.

Adult↗
PubMed1986

Cushing's syndrome in patients with the Zollinger-Ellison syndrome.

Reports of Cushing's syndrome in patients with the Zollinger-Ellison syndrome are rare, although up to 30 percent of gastrinomas contain ACTH-like immunoreactivity. We prospectively examined 75 patients with the Zollinger-Ellison syndrome for Cushing's syndrome. Three of 59 patients (5 percent) with the sporadic form of the Zollinger-Ellison syndrome had Cushing's syndrome, with severe symptoms due to ectopic production of ACTH. Each of these patients had metastatic gastrinoma, responded poorly to chemotherapy, and died within three years of the diagnosis of both syndromes. Three of 16 patients (19 percent) with the Zollinger-Ellison syndrome and multiple endocrine neoplasia type 1 had Cushing's syndrome due to pituitary production of ACTH, and their symptoms were mild. The gastrinoma in these patients was localized, and the prognosis was excellent. Thus, Cushing's syndrome is more common in patients with the Zollinger-Ellison syndrome than was previously reported, occurring in 8 percent of all cases. Furthermore, Cushing's syndrome in patients with sporadic Zollinger-Ellison syndrome and in those with multiple endocrine neoplasia type 1 differ in incidence, cause, clinical severity, extent of gastrinoma, the need for therapy, and prognosis. All patients with the Zollinger-Ellison syndrome and all patients with multiple endocrine neoplasia type 1 should be screened for Cushing's syndrome.

Adrenocorticotropic Hormone↗
PubMed1986

Cholecystokinin antagonists.

The three classes of CCK antagonists illustrate the various factors governing affinity of the antagonists for the CCK receptor. The major influence in determining potency of the cyclic nucleotide derivatives, amino acid derivatives and C-terminal fragments of CCK, are hydrophobic forces. In contrast, structural requirements are the major influences in determining potency of the N-terminal fragments of CCK-26-33. The most potent CCK antagonist in each of the three classes is illustrated in Fig. 11. CBZ-CCK-27-32-NH2 is 30 times more potent than N-CBZ-cystine, which is, in turn, slightly more potent than Bt2 cGMP. All these CCK antagonists, however, are relatively weak. For example, CBZ-CCK-27-32-NH2 inhibits binding of 125I-CCK by 50% at a concentration of approximately 5 microM. In contrast, the agonist CCK-26-33 inhibits binding of 125I-CCK by 50% at a concentration of approximately 1 nM. The antagonists remain useful for analyzing those responses that are caused by CCK, though the relatively low potencies of the antagonists may limit their usefulness as antagonists of CCK in vivo systems. This limitation, however, may be only theoretical. For example, proglumide, which requires an in vitro concentration of 0.3 mM to cause half-maximal inhibition of binding of 125I-CCK, can inhibit the actions of CCK and gastrin in animals (Hutchison and Dockray 1980; Stubbs and Stabile 1985) and of gastrin in man (Lamers and Jansen 1983). Nevertheless, the identification of CCK antagonists with greater potency than those hitherto described will facilitate studies of the actions of CCK.

Amino Acids↗
PubMed1986

Aggressive resection of metastatic disease in selected patients with malignant gastrinoma.

Fifteen patients with Zollinger-Ellison syndrome followed at the National Institutes of Health with extensive metastatic disease had an actuarial 5-year survival of 20%. Therefore, in 1982 a prospective study to examine the effect and feasibility of removing all gross tumor in selected patients with extensive metastatic disease was instituted. Five patients with extensive metastatic gastrinoma confined to the abdomen in whom imaging studies suggested the possibility of complete surgical resection were entered into this study and underwent attempted complete surgical resection and chemotherapy with streptozotocin, doxorubicin, and 5-fluorouracil. Median follow-up was 24 months. Surgical resection of all gastrinoma was possible in 4/5 patients attempted. In one patient in whom all gross disease could not be resected, the residual tumor progressed and the patient died 19 months after operation. All four patients with all disease resected appeared to benefit since all of them had a significant reduction in antisecretory medications and are enjoying normal activity and work. Three patients have had no detectable tumor on follow-up, and two of these patients are clinically and biochemically "cured" with normal fasting gastrin levels and negative provocative gastrin tests at 14 and 32 months. Therefore, aggressive resection of metastatic disease in selected patients with malignant gastrinoma is recommended.

Abdominal Neoplasms↗
PubMed1986

Prospective study of gastrinoma localization and resection in patients with Zollinger-Ellison syndrome.

In 1982, a prospective study was initiated of 52 consecutive patients with proven Zollinger-Ellison syndrome (ZES), involving surgical exploration with the goal of removing the gastrinoma after an extensive protocol to localize the tumor. Each patient underwent ultrasound, computed tomography (CT) with oral/intravenous (IV) contrast, and selective arteriography. Eighteen patients had metastatic disease identified by imaging studies and confirmed by percutaneous biopsies, and two patients had multiple endocrine neoplasia type I (MEN-I) with negative imaging studies; therefore, these 20 patients did not undergo laparotomy. Each of the remaining 32 patients (3 with MEN-I and positive imaging studies) underwent laparotomy, and gastrinomas were removed in 20 patients. Preoperative ultrasound localized tumors in 20% of patients, CT in 40%, arteriography in 60%, and any of the modalities in 70% of patients. Infusion CT and arteriography were 100% specific. In 18 patients with either negative imaging (17) or false-positive imaging (1 ultrasound), gastrinomas were found and removed in six patients (33%). Twenty-four gastrinomas were found in 20 patients at laparotomy: eight in lymph nodes around the pancreatic head, four in the pancreatic head, one in the pancreatic body, three in the pancreatic tail, three in the pyloric channel, one in the duodenal wall, two in the jejunum at the ligament of Treitz, one in the ovary, and multiple liver metastases in one patient. If one excludes patients with MEN-I or liver metastatic disease, 12/28 (43%) of patients were biochemically "cured" immediately after operation. This result decreased to 7/23 (30%) with greater than 6 months follow-up. No patients with gastrinomas resected have developed recurrent gastrinoma on follow-up imaging studies (longest follow-up: 4 years). This study indicates that 95% of metastatic gastrinoma can be diagnosed before operation and that, by a combination of careful imaging studies and thorough exploration at surgery, 30% of patients with gastrinomas may be curable.

Adult↗
PubMed1986

Treatment of acid-peptic diseases by inhibition of gastric H+,K+-ATPase.

The substituted benzimidazoles are a new class of drugs with a unique antisecretory action. These agents have great potential for treatment of acid-peptic disease because they produce substantial, long-lasting inhibition of gastric acid secretion by inhibiting gastric H+,K+-ATPase in the gastric parietal cell. Clinical trials of omeprazole, a substituted benzimidazole, indicate that it is safe and effective for short-term treatment of patients with duodenal or gastric ulcer, and it is highly effective for long-term treatment of patients with Zollinger-Ellison syndrome.

Adenosine Triphosphatases↗
PubMed1986

Actions of vasoactive intestinal peptide and secretin on chief cells prepared from guinea pig stomach.

Vasoactive intestinal peptide and secretin increased cellular cAMP and pepsinogen secretion in dispersed chief cells from guinea pig gastric mucosa. With each peptide there was a close correlation between the dose-response curve for changes in cellular cAMP and that for changes in pepsinogen secretion. Vasoactive intestinal peptide-(10-28) and secretin-(5-27) had no agonist activity and antagonized the actions of vasoactive intestinal peptide and secretin on cellular cAMP and pepsinogen secretion. Studies of binding of 125I-vasoactive intestinal peptide and of 125I-secretin indicated that gastric chief cells possess four classes of binding sites for vasoactive intestinal peptide and secretin and that occupation of two of these classes of binding sites correlates with the abilities of vasoactive intestinal peptide and secretin to increase cellular cAMP and pepsinogen secretion. What function, if any, is mediated by occupation by the other two classes of binding sites remains to be determined.

Animals↗