Treatment of malignant carcinoid tumors with recombinant interferon alfa-2b: development of neutralizing interferon antibodies and possible loss of antitumor activity.

Twenty patients with malignant carcinoid tumors were treated for 6 months with recombinant interferon alfa-2b (IFN alpha-2b; Intron-A; Schering Corp., Bloomfield, NJ) at a mean dose of 5.9 megaunits three times per week. Eleven of the 20 patients (55%) had a greater than 50% reduction of tumor markers (urinary 5-hydroxyindoleacetic acid or plasma neuropeptide K), showing objective tumor response. Six patients (30%) had stable disease with no significant change in tumor markers or tumor size, and three (15%) had progressive disease with an increase in tumor markers and size. These results are similar to those reported earlier for treatment with natural leukocyte IFN in patients with carcinoid tumors. Only two patients (35%) had a slight reduction of tumor size after 6 months of treatment. Three patients developed neutralizing antibodies to IFN alpha-2b. Two of these patients initially showed an objective response, which lasted until IFN antibodies developed. In one of these patients, a change to human leukocyte IFN resulted in normalization of antibody titers within 3 months, and the patient had a second objective clinical response. There was no correlation between development of IFN antibodies and development of autoimmune phenomena such as increased titers of antinuclear antibodies or thyroid autoantibodies. IFN alpha-2b seems to be as potent as human leukocyte IFN in the treatment of patients with malignant carcinoid tumors, but it is important to recognize that antibodies neutralizing IFN may develop in some patients, with concomitant loss of antitumor effects. A change to natural leukocyte IFN might be beneficial in these patients.

The oligomeric structure of rat liver microsomal glutathione transferase studied by chemical cross-linking.

The oligomeric structure of rat liver microsomal glutathione transferase was investigated using four different chemical cross-linking reagents. Studies were performed with the isolated enzyme, with the enzyme incorporated into phosphatidyl choline liposomes and with rat liver microsomes. Cross-linking was analyzed by use of SDS-PAGE combined with Western blotting. Our results strongly suggest that the microsomal glutathione transferase is a trimer in situ in the endoplasmic reticulum, as well as in the purified state and in proteoliposomes. These results lend strong support to previous studies, involving hydrodynamic characterization and radiation inactivation, indicating that the microsomal glutathione transferase is a trimeric enzyme.

Functional and structural membrane topology of rat liver microsomal glutathione transferase.

The membrane topology of rat liver microsomal glutathione transferase was investigated by comparing the tryptic cleavage products from intact and permeabilized microsomes. It was shown that lysine-4 of microsomal glutathione transferase is accessible at the luminal surface of the endoplasmic reticulum, whereas lysine-41 faces the cytosol. These positions are separated by a hydrophobic stretch of 25 amino acids (positions 11-35) which comprises the likely membrane-spanning region. Reaction of cysteine-49 of the microsomal glutathione transferase with the charged sulfhydryl reagent DTNB (2,2'-dithiobis(5-nitrobenzoic acid)) in intact microsomes further supports the cytosolic localization of this portion of the polypeptide chain. The role of two other potential membrane-spanning/associated segments in the C-terminal half of the polypeptide chain was examined by investigating the association of the protein to the membrane after trypsin cleavage at lysine-41. Activity measurements and Western blot analysis after washing with high concentrations of salt, as well as after phase separation in Triton X-114, indicate that this portion of the protein also binds to the membrane. It is also shown that cleavage of the purified protein at Lys-41 and subsequent separation of the fragments obtained yields a functional C-terminal polypeptide with the expected length for the product encompassing positions 42-154. The location of the active site of microsomal glutathione transferase was investigated using radiolabelled glutathione together with a second substrate. Since isolated rat liver microsomes do not take up glutathione or release the glutathione conjugate into the lumen, it can be concluded that the active site of rat liver microsomal glutathione transferase faces the cytosolic side of the endoplasmic reticulum.

Kinetic studies on rat liver microsomal glutathione transferase: consequences of activation.

Rat liver microsomal glutathione transferase is activated by sulfhydryl reagents and proteolysis. This property varies, however, depending on the combination, concentration and reactivity of the substrates. Thus, a multi-dimensional diagram can be envisioned in which the parameters affecting enzyme activity and activation are visualized. In principle activation could stem from an alteration in enzyme mechanism, transition-state complementarity, product release rate or pH-rate behaviour. These studies appear to rule out these possibilities and an alternate hypothesis is suggested based on the following experiments: (i) alternate substrate diagnosis of the kinetic mechanism of microsomal glutathione transferase indicates a random sequential mechanism. Non-activated and activated enzyme follow the same mechanism by these criteria. (ii) The microsomal glutathione transferase stabilizes a Meisenheimer complex between 1,3,5-trinitrobenzene and glutathione. The formation constants were similar for the unactivated and activated enzyme ((15 +/- 1).10(3) and (14 +/- 1).10(3) M-1, respectively, at pH 8). Inasmuch as the Meisenheimer complex resembles the transition state there is no evidence for an increased stabilization upon activation. (iii) The catalytic rate constant kcat does not vary with the viscosity in the assay medium. Thus, product release is not rate limiting for the unactivated and activated microsomal glutathione transferase (with saturating 1-chloro-2,4-dinitrobenzene and varying GSH). (iv) The pH dependence of the Kf-values for Meisenheimer complex formation exhibited pKa values close to 6 for both the activated and unactivated microsomal glutathione transferase. The pH profile of kcat (with saturating 1-chloro-2,4-dinitrobenzene and variable GSH concentrations) showed apparent pKa values of 5.7 +/- 0.5 and 6.3 +/- 0.4 for the unactivated and activated enzyme, respectively, indicative of a very similar requirement for deprotonation of the enzyme-GSH-1-chloro-2,4-dinitrobenzene complex. (v) Examination of the kinetic parameters (obtained with GSH as the variable substrate against increasingly reactive electrophilic substrates) in Hammett plots shows that the activation mechanism entails a more efficient utilization of GSH. It is suggested that a higher rate of formation of the glutathione thiolate anion occurs in the activated enzyme.

Body weight, skeletal muscle morphology, and enzyme activities in relation to fasting serum insulin concentration and glucose tolerance in 48-year-old men.

Tissue samples were taken from the gastrocnemius muscle of 26 randomly selected, glucose-tolerant, 48-yr-old men. Hexokinase, phosphorylase, lactate dehydrogenase (LDH), succinate dehydrogenase, and lipoprotein lipase activity (LPLA), as well as the area per fiber type and capillary density, were determined. Mean fiber area correlated positively with relative body weight (r equals 0.53, P less than 0.01), but capillary density did not. The result is that, in cases of high body weight, each capillary supplies a larger muscle fiber area. Serum insulin concentration in the fasting state correlated positively with body weight (r equals 0.77, P less than 0.001) and with mean fiber area per capillary (r equals 0.87; P less than 0.001). Only during the latter part of an oral glucose tolerance test (OGTT) did blood glucose concentrations correlate with relative body weight and mean fiber area per capillary (r equals 0.42, r equals 0.51, P less than 0.05). A stepwise multiple regression analysis showed that the different muscle morphology measurements could account for 3/4 of the variation in the fasting serum insulin concentration, the fasting insulin/glucose ratio, and the blood glucose concentration at 120 min in the OGTT. Of the intracellular enzymes, only LDH (r equals -0.71, P less than 0.001) correlated with the mean fiber area per capillary. LPLA correlated with capillary density (r equals 0.66, P less than 0.001), and, long with the muscle morphology measurements, could account for 3/4 of the variation in serum triglyceride concentrations. The results show that a large mean muscle fiber area/capillary ratio indicates a morphologic imbalance, which is related to both glucose tolerance and various degrees of insulin sensitivity.

The effects of octreotide on basal and stimulated hormone levels in patients with carcinoid syndrome.

The carcinoid syndrome, a common feature of small intestinal carcinoid tumors with liver metastases, includes flushing, diarrhea, bronchoconstriction, and right heart failure. The etiology of the carcinoid syndrome is not well understood, but serotonin seems to be involved in the diarrhea, whereas tachykinins may play a role in the flush reaction. In a double blind placebo-controlled study, we studied the effect of octreotide in 20 patients with midgut carcinoid tumors and liver metastases. A sc injection of 50 micrograms octreotide caused a significant (P less than 0.001) decrease in median plasma tachykinins and serum pancreatic polypeptide, GH, and insulin for up to 4 h. Administration of octreotide (50 micrograms, twice daily, sc) caused a 26% decrease in urinary 5-hydroxyindoleacetia acid excretion, but the number of flushing attacks or bowel movements did not change significantly. A typical flush was provoked by pentagastrin, and plasma tachykinin and serotonin levels were measured. The flush reaction was graded on a 10-point visual analog scale. Octreotide (50 micrograms, sc) given 45 min before flush stimulation prevented tachykinin release completely and significantly reduced the median flushing score from 8.5 to 2. Placebo administered in the same way did not prevent tachykinin release after pentagastrin administration. Thus, octreotide prevents pentagastrin-induced flushing and the related hormonal changes in patients with the carcinoid syndrome.

Plasma chromogranin A in patients with multiple endocrine neoplasia type 1.

Plasma chromogranin A (CgA) has been claimed to be a sensitive marker for neuroendocrine tumors, but its role in the early diagnosis of multiple endocrine neoplasia type 1 (MEN 1) pancreatic endocrine tumors has not been evaluated. We measured CgA in 36 patients with MEN 1, of whom 9 lacked pancreatic involvement, 20 had biochemical evidence of pancreatic endocrine tumors, and 7 displayed radiologically detectable pancreatic tumors. CgA was also analyzed in 25 patients with sporadic pancreatic endocrine tumors, 39 subjects with inflammatory bowel disease, 7 patients harboring nonendocrine pancreatic disease, and 19 healthy controls. Four of 9 of the MEN 1 patients without pancreatic involvement had elevated CgA. Furthermore, 60% with biochemically unequivocal tumors and all with a radiologically visible tumor showed elevations. All 25 patients with sporadic pancreatic endocrine tumor had increased CgA, as had 28% of patients with inflammatory bowel disease and 57% with nonendocrine pancreatic disease. Mean day to day CgA variation was 29% (range, 0-113%) in the neuroendocrine tumor patients and 21.0% (range, 0.0-47%, within reference range) among healthy controls. In summary, nonendocrine diseases may cause elevation of CgA, and its spontaneous variation can be considerable. Plasma chromogranin A is the most sensitive of the basal markers for neuroendocrine tumors, but cannot replace other established measures when screening for early pancreatic involvement in MEN 1.

Multiple endocrine neoplasia type 1: a 10-year prospective screening study in four kindreds.

A total of 80 individuals in 4 kindreds with multiple endocrine neoplasia type 1 (MEN 1) have been subjected to repeated biochemical screening during a 10-yr period with the principal aim being to analyze characteristics of the developing pancreatic lesion. Age at presentation of the MEN 1 trait averaged 18 yr in 7 previously unaffected individuals, and this effect of the screening procedure represented a lowering by almost 2 decades. Pancreatic endocrine involvement was recognized at a mean age of 25 yr and constituted the presenting lesion in a majority of the patients. A standardized meal test and basal values of serum pancreatic polypeptide, insulin, proinsulin, and gastrin were the most efficient markers for the pancreatic lesion and preceded signs of pancreatic tumors upon radiological examinations by a mean of 3.5 yr. A 75% penetrance of the islet cell disease and 90% for primary hyperparathyroidism within the affected individuals equalled the prevalences reported in autopsy studies. Two of the kindreds showed signs of intrafamilial homogeneity with respect to the profile of peptide excess (P less than 0.05) and considerable discrepancy in the malignant potential of the pancreatic lesions. The results of early detection and surgical intervention of the pancreatic tumors in MEN 1 suggested an impact on morbidity, while any effect on the mortality of these individuals remains to be clarified.

Human liver microsomal glutathione transferase. Substrate specificity and important protein sites.

Human liver microsomal glutathione transferase displays the following glutathione peroxidase/transferase activities: dilinoleoylphosphatidylcholine hydroperoxide (0.03 and 0.17 mumol/min.mg, unactivated and N-ethylmaleimide-activated enzyme, respectively), linoleic acid hydroperoxide (0.09 and 0.15 mumol/min.mg), cumene hydroperoxide (0.04 and 3 mumol/min.mg), methyl linoleate ozonide (0.02 and 1.2 mumol/min.mg) and 1-chloro-2,4-dinitrobenzene (1.9 and 24 mumol/min.mg). The activation of glutathione peroxidase activities are much higher than previously observed. The activity towards a phospholipid hydroperoxide is noteworthy since protection against lipid peroxidation has been implied. Methyl linoleate ozonide has not previously been characterised as substrate for any microsomal glutathione transferase. Human liver microsomal glutathione transferase displays an isoelectric point of 9.4 and a structure in agreement with that deduced from the cDNA sequence. Gel electrophoretic analysis shows that proteolytic activation of the human enzyme corresponds to cleavage at Lys-41, thus defining the critical activation site.

Lipoprotein-lipase activity in human skeletal muscle and adipose tissue in the fasting and the fed states.

Sixteen healthy subjects, 7 females and 9 males, with a mean age of 25 years (range 22--29 years), were studied in the fasting state in the morning and 8 h later after partaking of breakfast, lunch and two small meals. The lipoprotein-lipase activity in the adipose tissue increased significantly from 80 +/- 32 to 117 +/- 61 nmol fatty acid released per gram and minute (nmol FA/g/min), whereas in skeletal-muscle tissue it decreased significantly from 25 +/- 11 to 17 +/- 9 nmol FA/g/min. The concentration of serum triglycerides increased significantly from 0.93 +/- 0.18 mmol/l (mean +/- SD) in the fasting state to 1.57 +/- 0.64 mmol/l in the fed state. In the fasting state the lipoprotein-lipase activity of skeletal muscle was inversely related to the ratio between the concentrations of insulin and glucagon.

Peptide hormone markers in screening for endocrine tumors in multiple endocrine adenomatosis type I.

In three families with the multiple endocrine adenomatosis type I (MEA I) trait, 51 members were investigated by measurement of circulating peptide hormones as tumor markers. Twenty-five of 51 members (49 percent) were considered to be affected by MEA I disorders. The incidence rose with age (75 percent in generation II). Both sexes were affected equally. Hyperparathyroidism was present in 20 of 25 affected members (80 percent), and pituitary tumors (prolactinomas) were found in four of 25 (16 percent). Endocrine pancreatic tumors were found in nine of 25 affected members (36 percent), but when "probable" tumors (seven) are included the frequency rises to 72 percent. Hyperparathyroidism was found in all except one member with proved lesions in other organs. Among patients with proved and possible endocrine pancreatic tumors, elevated serum levels of gastrin and pancreatic polypeptide were frequently found, 78 percent and 67 percent, respectively, and we suggest that serum gastrin and pancreatic polypeptide levels are the most useful screening markers at present for pancreatic lesions in MEA I.

Measurements of chromogranin A, chromogranin B (secretogranin I), chromogranin C (secretogranin II) and pancreastatin in plasma and urine from patients with carcinoid tumours and endocrine pancreatic tumours.

Chromogranins and/or secretogranins constitute a family of water-soluble acidic glycoproteins that are present in almost all endocrine, neuroendocrine and neuronal tissue. Antibodies against chromogranins have been widely used for immunohistochemical staining of endocrine tissue and tumours of neuroendocrine origin. Furthermore, measurements of circulating chromogranin A have been used as a reliable marker for neuroendocrine tumour growth. In this study, we describe the development of specific antibodies against chromogranin A, chromogranin B (secretogranin I), chromogranin C (secretogranin II) and pancreastatin. The antibodies were used for immunohistochemical staining of normal and neoplastic neuroendocrine tissue and development of reliable radioimmunoassays for chromogranin A, chromogranin B, chromogranin C and pancreastatin. In 44 patients with carcinoid tumours, 17 patients with sporadic endocrine pancreatic tumours and 11 patients with endocrine pancreatic tumours and the multiple endocrine neoplasia 1 syndrome, plasma measurements revealed elevated chromogranin A levels in 99%, elevated chromogranin B in 88%, elevated chromogranin C in 6% and elevated pancreastatin in 46% of the patients. Urinary measurements revealed elevated levels in 39%, 15%, 14% and 33% of the patients respectively. Gel permeation chromatography of plasma and urine showed that circulating chromogranin A, and immunoreactive fragments of chromogranin A, had a higher molecular weight distribution than the chromogranin A fragments excreted to the urine. Furthermore, it was noted that most of the patients excreting chromogranin A fragments to the urine had previously been treated with streptozotocin, a cytotoxic agent known to induce renal tubular dysfunction. The antibodies raised proved useful for immunohistochemical staining and visualised endocrine cells in pancreatic islets, adrenal medulla and the small intestine as well as in endocrine pancreatic tumours, pheochromocytoma and midgut carcinoid tumours. In conclusion, the antibodies raised were useful for both immunohistochemical staining of normal tissue and endocrine tumours as well as development of specific radioimmunoassays for plasma measurements of the different chromogranins. Furthermore, we show that plasma measurements of chromogranin A and B were superior to measurements of chromogranin C and pancreastatin and plasma measurements of the different chromogranins were more reliable as markers for tumour growth than the corresponding urine measurements.

Fragments of chromogranin A are present in the urine of patients with carcinoid tumours: development of a specific radioimmunoassay for chromogranin A and its fragments.

Chromogranin A is a well-known protein constituent in granules of neuroendocrine cells. It is also known that plasma levels of chromogranin A increase considerably in patients with neuroendocrine tumours and thus chromogranin A is used as a marker for these tumours. In the present study, we have shown that fragments of chromogranin A are excreted into the urine in some patients with carcinoid tumours. The chromogranin A molecule appeared in the urine N-terminally cleaved at amino acid positions 116 and 210, which are previously reported cleavage sites of the molecule. The fragments identified were mainly of about 35 kDa in size. The unprocessed chromogranin A molecule was not excreted in the urine. Five out of 40 patients excreting the fragments had slight tubular dysfunction in the kidneys. We also showed that these renally excreted split products of chromogranin A were immunogenic and could be used for production of antibodies against chromogranin A. These antibodies were used both for immunocytochemistry and for the development of a specific and sensitive radioimmunoassay for chromogranin A and its fragments. Measurements of plasma chromogranin A by radioimmunoassay appeared to be a better marker for tumour growth than were measurements of chromogranin A in the urine.

Studies on the activation of rat liver microsomal glutathione transferase in isolated hepatocytes.

The mechanism of activation of microsomal glutathione transferase in isolated liver cells by diisapropylidene acetone (phorone) was investigated. Phorone (1 mM) causes a time-dependent increase (up to 2.6-fold) in the glutathione transferase activity of microsomes isolated from treated hepatocytes. Since phorone reacts with sulfhydryl groups, the possibility that this compound activated microsomal glutathione transferase directly was studied. It was found that neither the activity of the purified enzyme nor that in isolated microsomes is affected by phorone. It has been suggested [Masukawa T and Iwata H, Biochem Pharmacol 35: 435-438, 1986] that activation of microsomal glutathione transferase by phorone in vivo is mediated through thiol-disulfide interchange involving oxidized glutathione (GSSG). It is shown here that the glutathione transferase activity of isolated microsomes, which was increased by the addition of 10 mM GSSG, can be decreased to the basal level with 0.1 M dithioerythritol. Dithioerythritol, on the other hand, only marginally decreases the glutathione transferase activity in microsomes isolated from phorone-treated hepatocytes. This finding argues against a role for thiol-disulfide interchange in the activation of the enzyme by phorone. Furthermore, the glutathione depletion caused by phorone does not seem to be responsible for activation per se, since other thiol depletors [e.g. diethylmaleate (DEM)] do not affect the activity of the enzyme. Immunoblot analysis of microsomes isolated from phorone-treated hepatocytes did not reveal any partial proteolysis which might have accounted for the activation. It is suggested that activation of microsomal glutathione transferase by phorone proceeds through a mechanism which might reflect an in vivo regulation of this enzyme. Additional compounds which have been shown to activate the microsomal glutathione transferase in vivo were also tested and significant activation was obtained with 1,2-dibromoethane (1.4-fold) but not with DEM or carbon tetrachloride. Activation was also obtained with 1-chloro-2,4-dinitrobenzene (CDNB) (1.6-fold) and to a small extent with t-butyl hydroperoxide (1.2-fold). The activation by 1,2-dibromoethane and CDNB is probably mediated through covalent binding, considering the known alkylating properties of these compounds. CDNB is the first substrate shown to activate the microsomal glutathione transferase implying that electrophilic compounds which are substrates can increase the rate of their own elimination by reacting with this enzyme. In addition, activation by t-butyl hydroperoxide indicates that oxidative stress can activate microsomal glutathione transferase.

Mechanism of activation of rat liver microsomal glutathione transferase by noradrenaline and xanthine oxidase.

Activation of glutathione transferase activity in rat liver microsomes under a variety of conditions producing oxidative stress was investigated. Neither hydrogen peroxide (10 mM) (added or produced endogenously by glucose + glucose oxidase) nor duroquinone together with an NADPH-regenerating system (which generates the superoxide anion radical) had any significant effect on the glutathione transferase activity towards 1-chloro-2,4-dinitrobenzene. On the other hand, incubation of microsomes with 1 mM noradrenaline (which autooxidizes and generates superoxide anion radical) gave a 160% activation, as shown earlier (Aniya and Anders, J Biol Chem 264: 1998-2002, 1989). This was taken as an indication that microsomal glutathione transferase could be activated by oxidative stress. Here, we demonstrate that activation by this compound is due to covalent binding (presumably of the quinone formed during autooxidation). The xanthine/xanthine oxidase system, which generates the superoxide anion radical and hydrogen peroxide, increases microsomal glutathione transferase activity, but this activation was not dependent on the presence of xanthine. Western blots of microsomes treated with xanthine oxidase revealed that activation was due to proteolysis (presumably by contaminating proteases in the xanthine oxidase). In conclusion, there is no firm evidence that rat liver microsomal glutathione transferase is activated directly by reduced oxygen species in the microsomal system. The possibility remains that oxidative stress triggers secondary mechanisms such as generation of reactive intermediates and/or activation of proteolysis, which can in turn increase enzyme activity.

Ontogenesis of rat liver microsomal glutathione transferase.

The ontogenesis of rat liver microsomal glutathione transferase was investigated by activity measurements and immunochemical methods. The activity rises from a very low level (3% of adults) at day 8 pre-partum to adult levels at days 50-150. Increases are associated with the neonatal and late-suckling clusters. Interestingly the capacity to become activated by N-ethylmaleimide is much lower in females early and late in life (days 35-100 and 300-550). After the initial increases (from 10% of adult levels at day 8 pre-partum), protein levels determined immunochemically remain constant throughout life with no apparent sex differences. The developmental pattern of microsomal glutathione transferase resembles those of other drug-metabolizing enzymes indicating that the function of the enzyme is required in adult life.

The distribution of microsomal glutathione transferase among different organelles, different organs, and different organisms.

In the present study we have used both enzyme assay with 1-chloro-2,4-dinitrobenzene as substrate and immunochemical quantitation to examine the distribution of microsomal glutathione transferase in different organelles, in different organs, and in different organisms. This enzyme was found to constitute 3% and 5%, respectively, of the total protein recovered in the microsomal and outer mitochondrial membrane fractions from rat liver. Microsomal glutathione transferase present in other subcellular fractions can be accounted for by contamination by the endoplasmic reticulum. In contrast to the situation with rat liver microsomes the glutathione transferase activities of microsomes from extrahepatic tissues of this same animal could not be activated by treatment with N-ethylmaleimide. Nonetheless, significant albeit low levels of a protein with the same molecular weight and immunochemical properties as the rat liver enzyme could be detected in microsomes from several extrahepatic tissues, notably the intestine, the adrenal, and the testis. Of those mammals for which fresh liver could be obtained, all demonstrated N-ethylmaleimide-activatable glutathione transferase activity in their liver microsomes. On the other hand, representatives for fish, birds, and amphibia did not demonstrate such activatable transferase activity in their liver microsomes. Toad was the only species that had a notable (twofold) sex difference in their level of hepatic microsomal glutathione transferase activity.

Serum gastrin and chromogranin A during medium- and long-term acid suppressive therapy: a case-control study.

BACKGROUND: Serum chromogranin A (CgA) is regarded as a reliable marker of neuroendocrine proliferation. We previously described increased serum CgA levels during short-term profound gastric acid inhibition. AIM: To investigate serum gastrin and CgA levels in dyspeptic patients during continuous medium- (6 weeks to 1 year), or long-term (1-8 years) gastric acid suppressive therapy. PATIENTS AND METHODS: 114 consecutive dyspeptic patients referred for upper gastrointestinal endoscopy were enrolled in a cross-sectional, case-control study [62 patients on continuous antisecretory therapy, either with proton pump inhibitors (n = 47) or H2-receptor antagonists (H2RA) (n = 15) for gastro-oesophageal reflux disease with or without Barrett's oesophagus or functional dyspepsia, and 52 age- and sex-matched patients without medical acid inhibition and with normal endoscopic findings (control group)]. Omeprazole doses ranged from 20 mg to 80 mg daily and ranitidine from 150 mg to 450 mg daily. Fasting serum CgA and serum gastrin levels were measured by radioimmunoassay (reference values: serum CgA < 4.0 nmol/L; serum gastrin < 85 ng/L). RESULTS: Fasting serum CgA levels positively correlated with serum gastrin in the entire study population (r = 0. 55, P = 0.0001). Median serum CgA values were higher in patients treated with a proton pump inhibitor than H2RA [2.8 (2.0-5.9) nmol/L vs. 2 (1.9-2.3) nmol/L, P < 0.002] and controls [2.8 (2.0-5.9) nmol/L vs. 1.8 (1.5-2.2) nmol/L, P < 0.0001) and did not differ between patients treated with H2RA or controls. Serum gastrin and CgA levels in patients on proton pump inhibitor therapy positively correlated with the degree and duration of acid inhibition. Patients on long-term proton pump inhibitor therapy had significantly higher fasting serum gastrin and CgA than those on medium-term proton pump inhibitor therapy [127 (73-217) ng/L vs. 49 (29-78) ng/L, P < 0.0001 and 4.8 (2.8-8) ng/L vs. 2.1 (1.9-2.6) ng/L, P < 0.001]. No such relation was found in patients on medium- vs. long-term H2RA. Overall, patients with positive Helicobacter pylori serology had higher serum gastrin and CgA levels than those with negative H. pylori serology [51 (27-119) ng/L vs. 27 (14-79) ng/L, P = 0.01, 2.4 (1.9-3.4) nmol/L vs. 2.0 (1.7-2.5) nmol/L, P = 0.05]. CONCLUSIONS: During long-term continuous proton pump inhibitor treatment, serum gastrin and CgA levels are significantly elevated compared to H2RA treatment and nontreated dyspeptic controls. H. pylori infection seems to affect gastric ECL cell secretory function. Increased serum CgA values during long-term profound gastric acid inhibition could reflect either gastric enterochromaffin-like cell hyperfunction or proliferative changes.

Low levels of somatostatin in human CSF mark depressive episodes.

Somatostatin-like immunoreactivity was measured in the cerebrospinal fluid (CSF) of 85 inpatients with current or recent episodes of major depressive disorders, diagnosed according to Research Diagnostic Criteria (RDC) as assessed with the Schedule for Affective Disorders and Schizophrenia (SADS). Several biopsychiatric tests were run during the same week of investigation. Results indicate low levels of CSF somatostatin to be a state marker for episodes of depression characterized by sad appearance, feelings of tiredness, insomnia, and subjective inability to acknowledge any external precipitants for the depression. CSF somatostatin was negatively related to platelet monoamine oxidase (MAO) activity; MAO activity appeared to account better for the degree of melancholic features than did somatostatin. The ratio between 3-methoxy-4-hydroxyphenylglycol (MHPG) and homovanillic acid (HVA) in CSF also correlated negatively with somatostatin. A positive relationship was noted between CSF xanthine and somatostatin. There was a highly significant curvilinear correlation between CSF somatostatin and serum TSH concentrations, but no correlations between CSF somatostatin and serum GH or prolactin, or with plasma cortisol before or after dexamethasone.

Impaired glucose handling in active rheumatoid arthritis: effects of corticosteroids and antirheumatic treatment.

Forty-two patients with active rheumatoid arthritis were studied serially with respect to glucose metabolism after the institution of different anti-inflammatory and antirheumatic therapies. Sixteen patients received 20 mg of prednisolone daily. After 1 week of treatment the mean k value in glucose tolerance tests increased from 1.0 +/- 0.1 (SEM) to 1.6 +/- 0.1 (P less than .001). The corticosteroid therapy thus restored the glucose tolerance to normal and significantly enhanced the insulin response (P less than .01). Corticosteroids also normalized the growth hormone response to glucose infusion but had no effect on plasma glucagon. Treatment with nonsteroidal anti-inflammatory drugs did not affect the k values nor the hormonal pattern either after short-term treatment or after three months of therapy, except for causing a minor increase in the plasma glucagon levels both before and after glucose infusion. The long-term effects of treatment with penicillamine (n = 4), chloroquine (n = 7), and immunosuppressive agents [corticosteroids combined with azathioprine or cyclophosphamide (n = 7)], were an improvement of the clinical state, a reduction of the inflammatory activity, and a reversal of the glucose handling to normal.