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Background Previous studies have established short-term variability in the circulating plasma levels of cardiac peptides such as atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP). Our aim was to investigate whether such variable patterns could be observed in other vasoactive peptides. Methods We measured the immunoreactivity of vasoactive intestinal polypeptide (VIP), neuropeptide Y (NPY), endothelin-1 (ET-1) and calcitonin gene-related peptide (CGRP) in peripheral venous plasma collected at 2-min intervals over a 20-min period from patients with chronic cardiac failure (CCF) and from control subjects. In a second study, blood samples were obtained at 2-min intervals from the pulmonary artery, femoral artery and antecubital vein from patients with normal cardiac function while right atrial pressure and heart rate were constant. Results Peripheral blood VIP, NPY and ET-1 had peaks and troughs (levels > 2SD from the mean) in both patients and controls, with approximate intervals of 10 min. Levels of CGRP showed little variation. The overall levels [median (range); pmol L−1] of VIP [patients 27 (2.1–85.5); controls 9.8 (0–34)] and NPY [patients 20 (0–110); controls 12 (5–19)] were higher in patients (P

Aims Previous work has described short-term variation in the circulating plasma level of atrial natriuretic peptide (ANP), but the mechanism remains unknown. Our aim was to investigate the role of cardiac innervation in this variability. Methods and Results Blood samples were obtained from the right atrium via a pulmonary artery flotation catheter every 2min over a 90min period. Seven patients who underwent cardiac transplantation by the standard biatrial technique (partial innervation) and ten patients who underwent transplantation by the bicaval technique (total denervation) were studied. ANP levels were measured by radioimmunoassay. The median ANP levels were somewhat higher in the biatrial group compared to the bicaval group [470 (150–1095) vs 216 (100–605) pg.ml−1; median (range); P =ns], and both were much higher than normal levels in the pulmonary artery (40 (24, 56) pgml−1; median and interquartile range). In both transplant groups circulating plasma ANP levels showed considerable variability. The median number of ‘peaks’ and ‘troughs’, as counted by visual inspection, were not significantly different between the two groups. Computer analysis identified 12–16 and 6–15 ‘pulses’ in the biatrial and bicaval group, respectively. Further analysis revealed that pulse amplitude, height and area were significantly higher in the biatrial compared to the bicaval group. Conclusion It would appear that variability of circulating plasma levels of ANP is preserved despite complete or partial cardiac denervation, and so a neural mechanism does not appear to account for such variation.

Hyperglycaemia slows gastric emptying in both normal subjects and patients with diabetes mellitus. The mechanisms mediating this effect, particularly the potential role of insulin, are uncertain. Hyperinsulinaemia has been reported to slow gastric emptying in normal subjects during euglycaemia. The purpose of this study was to evaluate the effect of euglycaemic hyperinsulinaemia on gastric emptying in Type I (insulin-dependent) and Type II (non-insulin-dependent) diabetes mellitus. In six patients with uncomplicated Type I and eight patients with uncomplicated Type II diabetes mellitus, measurements of gastric emptying were done on 2 separate days. No patients had gastrointestinal symptoms or cardiovascular autonomic neuropathy. The insulin infusion rate was 40 mU · m–2· min–1 on one day and 80 mU · m–2· min–1 on the other. Gastric emptying and intragastric meal distribution were measured using a scintigraphic technique for 3 h after ingestion of a mixed solid/liquid meal and results compared with a range established in normal volunteers. In both Type I and Type II patients the serum insulin concentration had no effect on gastric emptying or intragastric meal distribution of solids or liquids. When gastric emptying during insulin infusion rates of 40 mU · m–2· min–1 and 80 mU · m–2· min–1 were compared the solid T50 was 137.8 ± 24.6 min vs 128.7 ± 24.3 min and liquid T50 was 36.7 ± 19.4 min vs 40.4 ± 15.7 min in the Type I patients; the solid T50 was 94.9 ± 19.1 vs 86.1 ± 10.7 min and liquid T50 was 21.8 ± 6.9 min vs 21.8 ± 5.9 min in the Type II patients. We conclude that hyperinsulinaemia during euglycaemia has no notable effect on gastric emptying in patients with uncomplicated Type I and Type II diabetes; any effect of insulin on gastric emptying in patients with diabetes is likely to be minimal. [Diabetologia (1999) 42: 365–372]

In this study, the distributions of calcitonin gene-related peptide, neuropeptide Y, and α-atrial natriuretic peptide 1–28 immunoreactivity, were investigated within different regions of the guinea pig heart by utilising two different methods of tissue fixation for the immunocytochemistry. The results were compared with data obtained through radioimmunoassays. We observed similar concentrations and distributions of α-atrial natriuretic peptide in the right atrium, with results of radioimmunoassay and immunocytochemistry, but there were no myocytes containing α-atrial natriuretic peptide in the left atrium or ventricles with immunocytochemistry as opposed to radioimmunoassay. The immunoreaction obtained for neuropeptide Y was more intense in the right ventricle than left. Calcitonin gene-related peptide nerve fibres were about twice as abundant in the left atrium than in the right.

C CLARKE, CG BRENNAN, K RODGERS, RM DWYER, PPA SMYTH ENDOCRINE LABORATORY, DEPARTMENT OF MEDICINE AND THERAPEUTICS, UNIVERSITY COLLEGE DUBLIN, IRELAND he demonstration in extrathyroidal human tissues of the sodium iodide symporter (NIS) has raised the possibility that 1311, commonly used as a systemic therapeutic ablative agent in hyperthyroidism and thyroid cancer, might be applied in the treatment of tumours in other NISexpressing tissues such as human breast cancer. Thyroidal transport of 1311 is known to be proportional to circulating stable I and the aim of this study was to determine how stable I (KI) would effect such transport in human breast cancer cell lines MDA-MB-231, MCF-7 and in FRTL-5 thyroid cells. All cells were incubated with KI (01 00mM) for 72 hours after which 1Th I was added . Incubation and uptake of 'l by cells was counted every four hours. Timed efflux of '^I was measured every five minutes. KI in the incubation medium blocked 1251 uptake in a dose-dependent manner in the E receptor positive MCF7 cell line. The effect was less marked in the E receptor negative MDA-MB-231 with significant uptake being maintained even at an I concentration of 50mM. A similar blockade was seen in the FRTL-5 cells with maximum uptake blockade of 25mM I. The rate of efflux of 15I was similar in both MCF-7 and MDA-MB-231 cell lines with a tin of 35 and 40 minutes respectively. In contrast, efflux from the FRTL-5 cells was faster (tire=15 mins). As the human breast has a much lower avidity for I than the thyroid, control of dietary intake would assume even greater importance in radioactive iodine treatment of breast tumours or their metastases.

A wide variety of neuroendocrine tumours express somatostatin receptors, and can be visualized by radiolabelled somatostatin analogue scintigraphy. To investigate the value of [111In]-octreotide scintigraphy (Octreoscan), 48 patients (37 with proven carcinoid, pancreatic endocrine and medullary carcinoma of thyroid tumours, 11 with neuroendocrine syndromes multiple endocrine neoplasia (MEN-I) and Zollinger-Ellison syndrome (ZES) were examined with 111In-DTPA-D-Phe1-octreotide. Scintigrams were obtained at 24 and 48 h, and the results were compared with CT and magnetic resonance imaging (MRI). Thirty-five of 48 patients had positive [111In]-octreotide scintigraphy (23/25 (92%) carcinoids, 8/9 (89%) PETs, 4/11 (36%) MEN-I & ZES). Of the 42 lesions located by conventional imaging techniques, 37 (88%) were also identified by Octreoscan. Unexpected lesions (40 sites), not detected by CT or MR imaging were found in 24/48 (50%) patients. [111In]-octreotide scintigraphy has a higher sensitivity for tumour detection, and is superior to MR imaging and CT scanning in the identification of previously unsuspected extraliver and lymph node metastases. It may also be helpful for the localization of clinically suspected tumours in patients with MEN-I and ZES.

Objective The somatostatin analogue octreotide (Sandostatin, Novartis, Basie) significantly improves the syndromes suffered by most patients with neuroendocrine tumours (NETs). The use of [111In-DTPA-D-Phe1]-octreotide scintigraphy ([111In]-pentetreotide) to predict the response to octreotide treatment has been described. Short-term hormone inhibition by a single injection of octreotide has also been reported. This study aimed to compare the effects of the suppression test with the response to long-term somatostatin analogue treatment, and to seek a correlation between the short-term suppression test, [11In]-pentetreotide observations and long-term somatostatin analogue treatment. Design and measurements Short octreotide suppression test and octreotide scintigraphy. Blood samples were collected before (0900, 0930 h), at (1000 h), and after (1030, 1100, 1200, 1300 h) the injection of 50 micrograms octreotide subcutaneously. Plasma hormones relevant to the syndrome were analysed by radioimmunoassay. The short suppression effects, the [111In]-pentetreotide observations and the response to long-term treatment with somatostatin analogue were evaluated and compared. Patients Twenty-six patients with metastatic NETs were evaluated, including 14 carcinoid tumours, 10 pancreatic endocrine tumours and 2 medullary carcinomas of thyroid (MCTs). Twelve patients had received octreotide treatment before the study, another 4 patients were treated subsequently with somatostatin analogue. Results During the short suppression test, hormones relevant to the syndromes were suppressed in 24 patients (those with carcinoids and pancreatic endocrine tumours). There was no suppression in the 2 patients with MCT. [111In]-pentetreotide observations closely correlated with the short suppression response to octreotide. Fourteen patients were treated with somatostatin analogue, and responded clinically; they had a positive short inhibition test and positive tumour uptake. Two patients with MCT did not respond to the treatment and had a negative suppression test and a negative [111In]-pentetreotide. Conclusion Our results suggest that a consistent relationship exists between the short suppression test and the response to somatostatin analogue treatment in the majority of the patients with neuroendocrine tumours. The octreotide suppression test and octreotide scintigraphy together will be helpful in selecting appropriate patients for clinical treatment with somatostatin analogues.

OBJECTIVE The hemodynamic, respiratory, and metabolic responses to exercise were studied in IDDM patients and control subjects to detect diabetic cardiomyopathy. RESEARCH DESIGN AND METHODS Eight subjects aged 25–40 years with diabetes of at least 10 years' duration were compared with eight control subjects aged 21–46 years. All subjects underwent a progressive incremental bicycle exercise test with measurement of gas exchange, blood glucose, lactate, fat metabolite, and catecholamine levels and two steady-state exercise tests with measurement of cardiac output by a CO2 rebreathing method. A new first-pass radionuclide method was used to measure cardiac ejection fractions (EFs) at rest, peak exercise, and steady-state exercise. RESULTS The peak achieved oxygen consumption was similar in the diabetic and control subjects (29.9 [25.1–34.6] and 31.4 [26.9–35.9] ml . min−1 . kg−1, respectively; mean [95% CI]). There were no significant differences in heart rate, double product, ventilation, respiratory exchange ratio, or ventilatory equivalents for oxygen and CO2 during the incremental test. Glucose levels were higher in the diabetic subjects, but there were no significant differences in levels of lactate, catecholamines, free fatty acids, glycerol, or β-hydroxybutyrate. Left ventricular EF fell from rest to peak exercise within the diabetic group (66.0% [59.6–72.4] at rest; 53.6% [45.6–61.6] at peak; P < 0.05) but this did not differ significantly from the control group (58.7% [52.3–65.1] at rest; 60.3% [48.9–71.7] at peak). Right ventricular EFs were similar in each group, and there was no reduction in peak filling rate to suggest diastolic dysfunction. The cardiac output responses to exercise were also similar in the two groups. CONCLUSIONS There is no evidence of impairment of the exercise response in subjects with long-standing diabetes, and the apparent fall in left ventricular EF at peak exercise could be related to hemodynamic adaptation.

We have previously shown an increased incidence of alpha-subunit-producing thyrotroph tumors after salmon calcitonin (sCT) injection into rats. However, it is not clear whether the effects of CT are direct or indirect. Our hypothesis was that for sCT to act directly, it must have a binding site on thyrotrophs. The alpha TSH cell line was used as a model for thyrotrophs. Receptor binding studies using alpha TSH membranes revealed a high affinity binding site for sCT [IC50 = 0.97 +/- 0.18 nM (n = 4); Kd = 5.45 +/- 0.43 nM (n = 3); binding capacity = 6.6 pmol/mg protein (n = 3)]. Rat CT did not compete with binding at this site. Receptor screening for other CT peptide family members revealed high specific binding for CT gene-related peptide (CGRP; IC50 = 0.25 +/- 0.08 nM; n = 3) and islet amyloid polypeptide (IC50 = 4.36 +/- 1.1 nM; n = 3). This together with the absence of rat CT binding excluded a conventional CT-binding site, and we propose a site similar to the CGRP subtype III receptor described in the rat nucleus accumbens. Guanosine 5'O-(3-thiotriphosphate) (GTP gamma S) (20 microM), reduced [125I]CGRP binding to 38% of maximal, indicating that this site is G-protein coupled. Immunocytochemically, all of the cells displayed intense sCT-like immunoreactivity, which was totally abolished by preabsorption of the antibody with sCT. The presence of this receptor supports the hypothesis that sCT mediates tumorigenesis via a direct pituitary action and, together with the coexistence of a sCT-like peptide in these cells, provides evidence for a possible autocrine role of this peptide in the control of thyrotroph function.

Peripheral circulating levels of atrial natriuretic peptide may exhibit short-term variation compatible with a pulsatile pattern of secretion. We obtained samples every 2 min for 90 min from the antecubital vein of 16 patients with chronic cardiac failure and 13 controls. Overall levels were higher in the patients (median and quartiles 230 (125,325) vs. 26 (16,48) ng l-1; P0.001). In both groups there was considerable variability, with 10 (2-12) peaks, 9 (7-15) troughs (both defined as2 SD from the mean) and 16 (13-18) pulses (defined by computer) during the sampling period in controls, and a similar number in patients. We then carried out simultaneous sampling in the pulmonary artery, femoral artery and peripheral vein in eight subjects with normal cardiac function and six patients with impaired function due to valvular heart disease. The pattern of variability was preserved in all three sites in both groups, suggesting intermittent secretion rather than variable breakdown of the peptide in the lung. No changes in right atrial pressure or heart rate were observed to coincide with the variations, but levels of the peptide in the pulmonary artery correlated with right atrial pressure in patients (r = 0.87; P0.05). The mechanism of such periodicity and its pathophysiological importance remain unknown.

The effect of dietary fats on gastrin in the pyloric antrum and plasma of Wistar rats was examined. Two different age-groups of rats were fed on three different diets in which fat was in the form of menhadenoil (MO), hydrogenated coconut oil (CO) and safflower oil (SO) respectively. Control groups were fed on normal laboratory diet. Each diet was isoenergetic and no group showed significant differences in either food intake or weight gain during the experiment. Weaner rats fed on the MO diet exhibited significant reductions in both antral (P= 0.047) and plasma (P= 0.002) gastrin concentrations when compared with age-matched controls. Likewise, adult rats fed on the MO diet exhibited significant reductions in both antral (P= 0.008) and plasma (P= 0.002) gastrin concentrations. In addition, adult rats fed on the CO diet exhibited significant reductions in both antral (P= 0.047) and plasma gastrin(P= 0.002) concentrations. Rats from both age-groups fed on the SO diet exhibited no significant differences in gastrin concentrations when compared with their respective control groups. These findings indicate that the composition of dietary fat can have profound effects on both tissue and plasma concentrations of gastrin in rats.

The development of new smart sensing methodologies that provide improved sensitivity and/or specificity for rapid and accurate biosensing is highly desirable for in situ and in vivo cancer screening and detection of biological pathogens. However, to date clinical applications of cancer sensing schemes have been for the most part limited by the large patient-to- patient variations in optical response (e.g. fluorescence or Raman signals), as well as by the large variation in background signal levels. A novel biosensing scheme is presented that is based on our recent research showing that the biological matrix may be altered by low intensity (i.e., below the ablation threshold) ultraviolet radiation (primarily 193 to 213 nm) such that the intrinsic fluorescence response is perturbed. Specifically, a sequential combination of optical probing (e.g. fluorescence emission), UV photochemical perturbation, and repeat optical probing is explored as a new spectral dimension based on difference spectroscopy. It is expected that the response is strongly coupled to the local biomolecular matrix. Because the same targeted material is optically probed both before and after perturbation with the UV light source, the resulting differential response may help mitigate variations in the absolute optical response. Preliminary data is presented using imaging mode and spectroscopy modes for several organic matrices as a proof of concept.

Birefringent pulmonary talc granuloma are often found in lung biopsies from intravenous drug abusers (IVDA) but their clinico-pathological significance remains undefined.

A pilot study on exocrine pancreatic function, using the 2-day para-aminobenzoic acid (PABA) test, was performed on 21 healthy elderly and 26 healthy young subjects. A PABA excretion index (PEI) less than 55%, indicating moderate to severe exocrine pancreatic insufficiency (EPI), was found in 19% of the elderly group (95% confidence limits 5-42%). While the mean value of the PEI was significantly lower in the elderly compared with the young group (Mann-Whitney Z = 2.8, p less than 0.01), there was no significant difference when the elderly subgroup with PEI less than 55% was excluded. There was no evidence of a generalized moderate to severe decline in pancreatic exocrine function with increasing age; a mild to moderate decline cannot be excluded.

Sprague–Dawley rats (3 weeks old) were fed on isoenergetic diets in which 40 % of the total energy was provided as fat either in the form of butter (high saturated fat), olive oil (high monounsaturated fat) or maize oil (high polyunsaturated fat), with one group on low-fat (10% of total energy) standard diet as a control. Animals were killed after 8.4 (se 0.8) weeks by cardiac puncture. Similar pieces of jejunum and ileum were prepared for morphometric studies. Extracts of tissue from the proximal and distal segments of the whole small intestine from four animals per group were assayed using established techniques for enteroglucagon, motilin, neurotensin, somatostatin, substance P and vasoactive intestinal peptide (VIP). We found that maize oil and olive oil increased villus height: crypt depth ratio in both jejunum and ileum. Maize oil increased tissue concentrations of somatostatin (P< 0.05) and substance P (P< 0.005) in the proximal segment. Both maize oil and olive oil increased tissue concentrations of neurotensin and substance P (P< 0.005) in the distal segments. These observations may explain the improvement of intestinal absorption of fluid following supplementation with polyunsaturated fat

Two patients are reported who presented with symptoms characteristic of a pancreatic vipoma. The necessity to measure more than one plasma VIP level for diagnosis, and the delay between the onset of illness and diagnosis is illustrated by both cases. Evidence suggests that vipomas are still under reported. The evolution of sophisticated diagnostic and therapeutic modalities over the twenty-five years separating both presentations is discussed.

Chromogranin A (CgA) is a complex prohormone expressed as a constituent of the regulated secretory pathway of numerous neuroendocrine cells. Recent investigations have demonstrated that CgA is selectively cleaved to generate distinct peptides in different neuroendocrine tissues. This investigation employed a site-specific antiserum that detects residues 98-106 rat CgA to examine the amino-terminal processing of CgA to generate beta-granin and related peptides in rat neuroendocrine tissues. Immunohistochemistry revealed moderate to intense beta-granin-like immunostaining in cells scattered throughout the anterior pituitary, thyroid, in the islets of Langerhans and in the mucosa of the gastrointestinal tract. Variable intensities of immunostaining were observed in distinct clusters of chromaffin cells. Quantitatively, the highest concentration of beta-granin-like immunoreactivity was detected in pituitary extracts. Significantly lower concentrations were detected in adrenal and thyroid glands, brain, ventral and dorsal pancreatic lobes and gastrointestinal tissue extracts. Chromatography resolved three distinct beta-granin-like immunoreactants; a large CgA-like form, an intermediate molecular form presumably corresponding to beta-granin (rat CgA1-128) and small immunoreactants that coeluted with the synthetic peptide. Two beta-granin-like immunoreactants, 21 and 22 kDa, were detected following immunoblot analysis of pituitary extracts. This study has demonstrated that chromogranin A is subject to distinct amino-terminal patterns of tissue-and cell-specific processing to generate a beta-granin-like immunoreactant which is additionally cleaved in pancreatic, fundic and colonic tissue to generate previously unidentified peptides.

Chromogranin A (CgA), pancreastatin (PST), intervening-peptide (IP) and WE-14 antisera were employed to investigate the proteolysis of CgA in 50 pituitary adenomas. All non-functioning (NF) pituitary tumours (n = 28) exhibited CgA immunoreactivity. PST, IP and WE-14 immunostaining was observed in 85%, 89% and 67%, respectively. CgA, PST and IP immunostaining were comparable in the majority of NF tumours, while less intense WE-14 immunoreactivity was detected in a subpopulation of NF tumour cells. Approximately half of the functioning pituitary tumours expressed CgA immunoreactivity. Six of nine ACTH-secreting tumours displayed CgA and IP immunostaining; four of these tumours displayed PST immunoreactivity. WE-14 immunoreactivity was detected in one corticotroph tumour. Three of six growth hormone (GH) secreting tumours displayed CgA immunostaining, two exhibited PST and IP, and one exhibited WE-14 immunoreactivity. Clusters of WE-14 immunopositive cells were detected in one GH tumour. One of seven prolactinomas exhibited weak CgA immunostaining, while weak IP and WE-14 immunostaining was detected in an additional tumour. No PST immunostaining was detected in prolactinomas. Therefore CgA is a valuable marker of NF pituitary tumours, however it is a more sporadic marker of functioning adenomas. In general, the cellular pattern and intensities of CgA, PST and IP immunoreactivity were comparable in the majority of pituitary adenomas. In contrast, WE-14 immunostaining was observed in a subpopulation of tumour cells. The pathophysiological significance of the proteolysis of CgA to generate bioactive peptides in both NF and functioning pituitary adenomas remains to be established.

Previous studies have established short-term variability in the circulating plasma levels of cardiac peptides such as atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP). Our aim was to investigate whether such variable patterns could be observed in other vasoactive peptides.We measured the immunoreactivity of vasoactive intestinal polypeptide (VIP), neuropeptide Y (NPY), endothelin-1 (ET-1) and calcitonin gene-related peptide (CGRP) in peripheral venous plasma collected at 2-min intervals over a 20-min period from patients with chronic cardiac failure (CCF) and from control subjects. In a second study, blood samples were obtained at 2-min intervals from the pulmonary artery, femoral artery and antecubital vein from patients with normal cardiac function while right atrial pressure and heart rate were constant.Peripheral blood VIP, NPY and ET-1 had peaks and troughs (levels2SD from the mean) in both patients and controls, with approximate intervals of 10 min. Levels of CGRP showed little variation. The overall levels [median (range); pmol L-1] of VIP [patients 27 (2.1-85.5); controls 9.8 (0-34)] and NPY [patients 20 (0-110); controls 12 (5-19)] were higher in patients (P0.05). Circulating plasma levels of ET-1 and CGRP were about the same in both groups [ET-1: patients 18 (2-84); controls 18 (0-48); CGRP: patients 4 (1-18.5), controls 5.5 (1-15); P = NS]. Levels of CGRP, VIP and ET-1 were similar in the pulmonary and femoral arteries, whereas systemic arterial levels of NPY were higher than in the pulmonary artery.The data demonstrate marked variability in circulating levels of the neuropeptides studied. In addition, peaks and troughs were observed every 10-15 min from all three vascular beds. If these peptides are secreted in a pulsatile pattern, then interpretations of single measurements should be guarded. Furthermore, this study raises interesting questions about the physiology of hormone secretion in man.

In this study, the distributions of calcitonin gene-related peptide, neuropeptide Y, and alpha-atrial natriuretic peptide 1-28 immunoreactivity, were investigated within different regions of the guinea pig heart by utilising two different methods of tissue fixation for the immunocytochemistry. The results were compared with data obtained through radioimmunoassays. We observed similar concentrations and distributions of alpha-atrial natriuretic peptide in the right atrium, with results of radioimmunoassay and immunocytochemistry, but there were no myocytes containing alpha-atrial natriuretic peptide in the left atrium or ventricles with immunocytochemistry as opposed to radioimmunoassay. The immunoreaction obtained for neuropeptide Y was more intense in the right ventricle than left. Calcitonin gene-related peptide nerve fibres were about twice as abundant in the left atrium than in the right.

Although chromogranin A (CgA) is a recognized marker of neuroendocrine tumours, little is known about the distribution of the CgA-derived peptides, vasostatin (VST) I or II, in these tumours. Rabbit polyclonal antiserum was raised to a fragment of VST I and used to immunostain sections (5 microns) of wax-embedded tumour tissue. Immunoreactivity (IR) was detected using swine anti-rabbit fluorescein secondary antibody and sections were viewed by fluorescence microscopy. Of 24 tumours from patients with lung carcinoids, one was weakly positive, while 23 of 26 ileal carcinoid tumours were immunoreactive. Metastatic deposits from patients with ileal carcinoids also tended to be immunoreactive (9/10). The difference in IR between lung and ileal carcinoid primary tumours did not appear to be related to the metastatic potential, since appendiceal tumours, which seldom metastasize, also tended to be immunoreactive (4/6) for VST I. The strongest IR was recorded in two patients with flushing as a result of ileal carcinoids; five other 'flushers' with ileal carcinoids were also immunopositive for VST I-like IR. By contrast, patients with flushing as a result of lung carcinoids were immunonegative for VST. In conclusion, VST I-like IR may assist in the identification of a secondary deposit from an unknown primary site.

Autoantibodies arise when there is a breakdown in immunological tolerance. Autoantibodies to parietal cells and intrinsic factor are found in autoimmune atrophic gastritis (AAG) and are associated with elevated plasma gastrin. Endogenous gastrin autoantibodies have not been described to date. The aim of this study was to investigate the occurrence of autoantibodies to gastrin. Plasma from 50,000 patients, including more than 2000 with AAG, was tested. Gastrin was measured by radioimmunoassay (RIA) in whole plasma and the presence of autoantibody determined by using a control which omitted assay antibody. The quantity and affinity of gastrin autoantibodies was assessed. Three patients had autoantibodies to gastrin. All three had AAG and pernicious anaemia (PA). The antibodies were of low titre and relatively high affinity. Free circulating plasma gastrin levels were within the normal range, but total gastrin levels were elevated. This is the first description of autoantibodies to endogenous gastrin. The incidence of antibodies to gastrin is low, they are found in association with PA, and they may lead to falsely low measurements of plasma gastrin.

Medullary thyroid carcinoma (MTC) is an uncommon tumour of calcitonin-secreting C-cells of the thyroid gland. This cancer represents an important potential model for the study of mechanisms of human epithelial cell transformation. Although recent studies have identified the gene involved in familial forms of MTC, little is known about the molecular pathogenesis of the sporadic variants of this tumour. The biological and prognostic significance of TFF1 expression, particularly in diverse human malignancies, suggests that the TFF1 protein could have a role in human neoplasia. Furthermore, in prostate cancer it has been demonstrated that TFF1 expression is closely associated with premalignant changes and neuroendocrine differentiation. In the present study, the expression of TFF1 was analysed in 18 human MTCs, comprising sporadic and familial tumours, C-cell hyperplasia, and one case of lymph gland metastasis. TFF1 expression was also examined in the cultures of a human MTC-derived tumour cell line (TT cell line). The results showed that ten sporadic tumours, three hereditary tumours (including C-cell hyperplasia), and one lymph gland metastasis displayed TFF1 immunoreactivity. Indirect fluorescence immunocytochemistry and Western blotting revealed that the TFF1 protein was strongly expressed in the TT cells. Northern analysis revealed that tumours and TT cells expressed the TFF1 transcript. Although the function of TFF1 protein in the carcinogenesis of MTC remains to be elucidated, its expression in the majority of cases of both sporadic and hereditary tumours, metastatic tumours, and in C-cell hyperplasia suggests that it may contribute to the pathogenesis of MTC.

Medullary thyroid carcinoma (MTC) is a tumor of parafollicular cells of the thyroid gland. It has served as a useful experimental model for the study of tumor proliferation and differentiation. Although recent studies have identified the gene involved in familial forms of MTC, little is known about the molecular pathogenesis of the sporadic variants of this tumor. It has become increasingly clear that deregulation of programmed cell death is a critical component in multistep tumorigenesis. The present investigation was undertaken to determine whether similar molecular events occur in human MTC. Eighteen MTCs from 18 patients (including 12 sporadic and six familial cases and one metastatic lymph gland) and a MTC cell line (TT cells) were used in this study for detecting the expression of apoptosis-regulatory genes bcl-2, bax, c-myc, and p53. Immunohistochemical results showed that all MTC tumor samples displayed Bcl-2 and c-Myc immunoreactivity, whereas only 4 and 2 tumors showed a minority of cells positive for Bax and p53, respectively. Western and Northern blotting showed high levels of 26-kd Bcl-2 protein and bcl-2 transcript. The co-expression of Bcl-2 and c-Myc was also detected in the TT cells by indirect fluorescence immunohistochemistry and Western blotting. Moreover, Bcl-2 immunoreactivity was also found in C-cell hyperplasia from familial patients indicating that expression of this oncogene may represent an early event in the pathogenesis of MTC. The present study suggests that deregulation of programmed cell death may be a critical component in multistep tumorigenesis of MTC and that the frequent expression of the Bcl-2 oncoprotein in these tumors may contribute to their pathogenesis. The genetic complementation of simultaneously deregulated bcl-2 and c-myc may be implicated in the multistep tumorigenesis of human MTC.

Several genetic aberrations have been implicated in the carcinogenesis of small cell lung carcinomas (SCLCs), including tumour suppressor gene p53 deletion and mutation and amplification of the myc family proto-oncogenes. However, their exact ontogeny and carcinogenesis remain unknown. There are no proven aetiological factors for lung carcinoid tumours. Recent evidence suggests that the genetic regulation of apoptosis is of critical importance during tumourigenesis and that oncogene and tumour suppressor genes can regulate the rate, or susceptibility, of cells to undergo apoptosis. In this study, the expression of Bcl-2 protein has been investigated in 77 primary lung neuroendocrine tumours, including 55 SCLCs and 22 carcinoid tumours, and compared with p53 expression. Of the 77 tumours studied, Bcl-2 immunoreactivity was present in 80 per cent of SCLCs, 43 per cent of typical, and 67 per cent of atypical carcinoid tumours with more than 10 per cent tumour cell positivity. Western and Northern blot analysis revealed that carcinoid tumours expressed the 26 kD protein and bcl-2 transcripts. Whereas 42 per cent of the SCLCs studied displayed p53 protein immunoreactivity in more than 10 per cent of tumour cells, p53 positivity was not found in lung carcinoid tumours. There are statistical differences in Bcl-2 and p53 expression between SCLCs and lung carcinoid tumours. These results suggest that disregulation of the genetic mechanisms controlling apoptosis is a critical step in the progression of SCLC, and the expression of Bcl-2 is involved in the pathogenesis of SCLC and lung carcinoid tumours. The genetic complementation of simultaneously deregulated Bcl-2 and p53 may be implicated in the multistep tumourigenesis of small cell lung cancer.

The somatostatin analogue octreotide (Sandostatin, Novartis, Basie) significantly improves the syndromes suffered by most patients with neuroendocrine tumours (NETs). The use of [111In-DTPA-D-Phe1]-octreotide scintigraphy ([111In]-pentetreotide) to predict the response to octreotide treatment has been described. Short-term hormone inhibition by a single injection of octreotide has also been reported. This study aimed to compare the effects of the suppression test with the response to long-term somatostatin analogue treatment, and to seek a correlation between the short-term suppression test, [11In]-pentetreotide observations and long-term somatostatin analogue treatment.Short octreotide suppression test and octreotide scintigraphy. Blood samples were collected before (0900, 0930 h), at (1000 h), and after (1030, 1100, 1200, 1300 h) the injection of 50 micrograms octreotide subcutaneously. Plasma hormones relevant to the syndrome were analysed by radioimmunoassay. The short suppression effects, the [111In]-pentetreotide observations and the response to long-term treatment with somatostatin analogue were evaluated and compared.Twenty-six patients with metastatic NETs were evaluated, including 14 carcinoid tumours, 10 pancreatic endocrine tumours and 2 medullary carcinomas of thyroid (MCTs). Twelve patients had received octreotide treatment before the study, another 4 patients were treated subsequently with somatostatin analogue.During the short suppression test, hormones relevant to the syndromes were suppressed in 24 patients (those with carcinoids and pancreatic endocrine tumours). There was no suppression in the 2 patients with MCT. [111In]-pentetreotide observations closely correlated with the short suppression response to octreotide. Fourteen patients were treated with somatostatin analogue, and responded clinically; they had a positive short inhibition test and positive tumour uptake. Two patients with MCT did not respond to the treatment and had a negative suppression test and a negative [111In]-pentetreotide.Our results suggest that a consistent relationship exists between the short suppression test and the response to somatostatin analogue treatment in the majority of the patients with neuroendocrine tumours. The octreotide suppression test and octreotide scintigraphy together will be helpful in selecting appropriate patients for clinical treatment with somatostatin analogues.

Several studies have shown that hyperglycaemia slows gastric emptying in normal subjects and patients with diabetes mellitus but whether hyperinsulinaemia per se has an effect remains debatable. In the present study we have assessed the effect of hyperinsulinaemia on gastric emptying of a solid and liquid meal in normal subjects. Ten men were studied three times in random order. After an overnight fast, subjects were infused with 0.9 % NaCl on two occasions and on the third with insulin, at 40 mU · m−2· min−1 with 20 % glucose simultaneously to maintain euglycaemia. Steady-state glucose infusion rate was ensured before the subjects ate a standard meal of a pancake labelled with 99mTc and milkshake labelled with 111In-DTPA. Gamma-scintigraphic images were then obtained every 20 min for the next 3 h. There were no significant differences between the mean half-emptying times (T50) of the solid and liquid during the two saline infusions (129.6 ± 28.5 vs 128.4 ± 23.8 min for the solid and 25.4 ± 7.0 vs 34.7 ± 18.0 min for the liquid, mean ± SD). Hyperinsulinaemia delayed both solid (mean T50 149.6 ± 30.7, p = 0.031) and liquid emptying (mean T50 39.8 ± 13.9, p = 0.042). There were no significant differences in the cholecystokinin and glucagon-like peptide 1 responses to the meal during either saline or insulin infusions. There was a tendency towards a greater insulin response to the meal during the hyperinsulinaemic study. Thus, hyperinsulinaemia delayed emptying of both the solid and liquid components of the meal. [Diabetologia (1998) 41: 474–481]

That carotid body tumours have a genetic aetiology is suggested by the familial occurrence of the neoplasm. Environmental influences are also implied by the fact that the tumour is more common in those living at high altitudes. However, the mechanism of development of sporadic tumours occurring at sea level, which account for the majority of cases, remains unknown. It has become increasingly clear that the deregulation of programmed cell death is a critical component in multistep tumourigenesis. Previous studies have demonstrated a high frequency of bcl-2 expression in the tumours arising from cells derived from the neural crest and tumour cell lines of neural origin. This investigation was undertaken to determine whether similar molecular events occur in human carotid body tumours. Western and Northern analysis revealed that the tumours expressed the 26 kD protein and bcl-2 transcripts. Immunoperoxidase staining, using a monoclonal anti-bcl-2 antibody, revealed that 11 out of 13 specimens stained positively for bcl-2. These results suggest that the deregulation of programmed cell death may be a critical component in the multistep tumourigenesis of carotid body tumours and that the expression of oncoprotein bcl-2 may contribute to the generation of such tumours.

Neuroendocrine tumors of the gastroenteropancreatic system include pancreatic islet cell and carcinoid tumors. These tumors comprise a functionally and biologically heterogeneous group of neoplasms that rarely show reliable histopathologic signs of malignancy. No etiologic factors are proven to be associated with them, and their exact ontogeny and carcinogenesis remain unknown.Monoclonal antibodies were employed, along with microwave antigen retrieval and the avidin-biotin immunohistochemical method, to investigate the expression of c-myc, bcl-2, c-erb B-2, c-erb B-3, c-jun, and proliferating cell nuclear antigen (PCNA) in a retrospective series of 116 primary gastroenteropancreatic neuroendocrine tumors (GPNTs). The authors attempted to correlate this expression with the clinicopathologic outcome of the disease.Immunoreactivities for c-myc, bcl-2, c-erb B-2, c-erb B-3, and c-jun were detected in 100%, 45%, 24%, 7%, and 24% of pancreatic neuroendocrine tumors (PNTs), respectively. In carcinoid tumors, immunoreactivities were detected for c-myc (63%), bcl-2 (28%), c-erb B-2 (31%), c-erb B-3 (6%), and c-jun (23%). There were significantly higher incidences of c-myc, bcl-2, and c-erb B-2 immunoreactivities in carcinoid tumors of the rectum than in those of the appendix, and significantly higher incidences of bcl-2 and c-jun immunoreactivities in carcinoid tumors of the bronchus than in those of the appendix. Incidence of PCNA immunoreactivity was significantly higher in malignant than in benign PNTs and also significantly higher in carcinoid tumors of the jejunum and ileum than in those of the appendix.The oncogenes c-myc, bcl-2, c-erb B-2, and c-jun are frequently expressed in human GPNTs. The expression of these oncogenes may represent pathogenic events in the generation, malignant transformation, and progression of GPNTs. The immunohistochemical evaluation of cell kinetics in GPNTs by PCNA might be a useful adjunct to conventional diagnostic procedures.

pS2 protein expression has been demonstrated in a range of malignant tissues in an oestrogen-independent pathway. Recently, it has been demonstrated that pS2, in prostate cancer, is closely associated with neuro-endocrine differentiation. In the present study, we have analyzed, by immunohistochemistry along with microwave antigen retrieval, the expression of pS2 protein in a retrospective series of 236 human primary neuro-endocrine tumours and attempted to correlate this with the clinicopathologic features of patients and the presence of oestrogen receptor (ER). pS2 immunoreactivity was detected in 42% of small-cell lung carcinomas, 36% of lung carcinoids, 33% of phaeochromocytomas, 38% of carotid-body tumours, 31% of pancreatic neuro-endocrine tumours, 60% of stomach carcinoids, 55% of ileal carcinoids, 23% of appendiceal carcinoids and 86% of rectal carcinoids respectively in more than 10% tumour cells. No pituitary tumours displayed pS2 immunoreactivity. pS2 transcript was also detected in lung carcinoid and carotid-body tumours by Northern-blot analysis. There was a statistically higher incidence of pS2 expression in carcinoid tumours of the ileum and rectum than in those of the appendix. No association was observed between pS2 expression and the occurrence of the carcinoid syndrome; nor was any correlation observed between the occurrence of pS2 immunoreactivity and that of ER. Our results suggest that the expression of the pS2 protein in a wide spectrum of neuro-endocrine tumours may be implicated in the pathogenesis and progression of some neuro-endocrine tumours in an oestrogen-independent pathway.

Atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) are known to be elevated in patients with chronic heart failure at rest. While it is known that during exercise the circulating level of ANP increases in patients with heart failure, the response of BNP to exercise in these patients relative to control subjects is unclear. Ten patients with stable chronic heart failure and 10 normal control subjects performed symptom-limited exercise with respired gas analysis. All patients had depressed left ventricular ejection fractions (LVEF). Patients had lower peak oxygen consumption PVo 2 ) than the control group [median (range) 1.18 (098-1.76) vs. 1.94 (1.53-2.31) L min -1 ; P < 0.001]. Circulating plasma levels of ANP and BNP were higher at rest in patients than in control subjects [ANP 335 (140-700) vs. 90 (25-500) pg mL -1 ; BNP 42 (25-50) vs. 20 (10-20) pg mL -1 ], and at peak exercise [ANP 400 (200-1000) vs. 130 (10-590); BNP 46 (40-51) vs. 20 (10-30)]. The rise in ANP at peak exercise was significant in patients compared with the resting level, but not in control subjects. For BNP, there was a significant rise in patients but no change in control subjects. The circulating plasma levels of both peptides showed a strong negative correlation with LVEF (ANP, P < 0.005; BNP, P < 00001) and, to a less extent, with RVEF. It is possible that BNP may give a better indication of cardiac function.

Aims Candoxatril is a specific neutral endopeptidase (NEP) 24.11 inhibitor, and previous work has documented the effect of NEP inhibition on atrial and brain natriuretic peptides (ANP, BNP). The aim of the present study was to ascertain the effect of NEP inhibition on circulating levels of vasoactive peptides. Methods We studied seven patients with chronic heart failure who were randomized to receive candoxatril, candoxatril/captopril, captopril and placebo in a four way cross over, double-blind pattern. Results The mean circulating level of endothelin (ET) was increased 2 h after placebo (10 to 20 pg ml−1 ) and also calcitonin gene-related peptide (CGRP) (27 to 51 pg ml−1 ), but ANP levels changed little during this time (73 to 75 pg ml−1 ). Following candoxatril, however, ET (10 to 39 pg ml−1, P

Medullary thyroid carcinoma (MTC) is an APUDoma (APUD refers to amine precursor uptake and decarboxylation) arising from the parafollicular cells. Diarrhoea has been reported in some 30% of patients, variously attributed to excess production of calcitonin (CT), serotonin (5-HT), vasoactive intestinal peptide (VIP) or other factors. The regulatory factors in MTC were examined employing immunocytochemistry and RIA to tumours and their extracts. The patients were followed up for more than 15 years. CT and calcitonin gene-related peptide were universally expressed in all the tumours. The neuroendocrine markers chromogranin A (and its fragments pancreastatin and WE-14), neurone-specific enolase, protein gene product 9·5 and carcino-embryonic antigen were found in the majority of MTCs and might be useful as immunocytochemical markers. 5-HT, substance P, neurokinin A, glucagon and VIP could not be detected, excluding them as candidates in the diarrhoea of MTC. Journal of Endocrinology (1997) 152, 275–281

In 1993, a Japanese group reported the occurrence of a potent vasodilator peptide in acid extracts of a human phaeochromocytoma, using the activity of rat platelet cAMP activity as a biological assay, followed by HPLC purification and amino acid sequencing. The peptide consisted of 52 amino acids, had one intramolecular disulphide bond and an amidated C-terminal tyrosine, and was named adrenomedullin (AM). When AM was injected intravenously (3 nmol/kg) into rats, it resulted in a fall in blood pressure, lasting for 30-60 min. This was comparable to the hypotensive activity of calcitonin gene-related peptide (CGRP) (which is established as one of the strongest vasodilators). These findings led to the conclusion that AM is a potent and long-acting hypotensive peptide, with a putative role in blood pressure control.

AIMS/BACKGROUND: Whereas the control of hormone secretion from pituitary adenomas has been studied in considerable detail, the molecular events underlying the development of these tumours are still poorly understood. Abnormalities of some oncogenes and tumour suppressor genes have been previously reported to occur at very low frequencies. The aim of the present study was to assess the possible expression of the bcl-2 oncoprotein and to compare it with that of c-myc in pituitary adenomas. METHODS: Monoclonal antibodies were used, along with microwave antigen retrieval and the avidin-biotin immunohistochemical method, to investigate expression of the oncoproteins bcl-2 and c-myc in 30 primary pituitary tumours from five broad diagnostic groups and in five normal pituitaries. RESULTS: Bcl-2 and c-myc immunoreactivities were detected in nine (30%) and eight (27%) tumour samples, respectively. Of the nine bcl-2 and eight c-myc positive tumours, seven were positive for both oncoproteins and included one of the four corticotrophinomas studied, four of seven prolactinomas, one of two somatotrophinomas, and one of four oncocytomas. All 13 null cell adenomas studied were negative for both bcl-2 and c-myc immunoreactivities. CONCLUSIONS: These results indicate that the bcl-2 and c-myc oncoproteins are expressed abnormally in over one quarter of pituitary tumours. Most these tumours co-expressed both oncoproteins. The genetic complementation of simultaneously deregulated bcl-2 and c-myc is implicated, through the regulation of apoptosis, in the pathogenesis of pituitary tumours.