Unanticipated pregnancy with intrauterine growth retardation after radiation-induced ovarian failure. A case report.

BACKGROUND: Ovarian failure is common after pelvic irradiation and is dependent upon radiation dose and patient age. This case report demonstrates the resumption of ovulation and pregnancy subsequent to this diagnosis. CASE: An enlarging abdominal mass was noted in a 28-year-old female 20 months after resection of a pelvic hemangiopericytoma. She had received postoperative adjuvant hemipelvic radiotherapy and subsequently developed amenorrhea and symptoms of hypoestrogenism. Serum follicle-stimulating hormone (FSH) was elevated. In light of the diagnosis of ovarian failure, the finding of an intrauterine pregnancy on an abdominal computed tomography scout film, performed to rule out a recurrence of the primary tumor, was unexpected. CONCLUSION: While amenorrhea and elevation in serum gonadotropin levels are common after pelvic irradiation, the clinician must be cognizant of the potential for resumption of ovulation after radiotherapy. The diagnosis of ovarian failure should be based on more than a single serum FSH level. Further, radiation changes in the endometrium and myometrium as well as in uterine blood flow may have an adverse effect on pregnancy outcome. We suspect these effects had an etiologic influence on the fetal growth retardation in this pregnancy.

Effect of PACAP on gastric acid secretion in rats.

Pituitary adenylate cyclase-activating polypeptide (PACAP) is a new VIP-like brain-gut peptide. Its effects on the motility and secretory functions of the gastrointestinal system have been shown in previous studies. In this study we investigated the effect of intravenous PACAP on gastric acid secretion in conscious pylorus-ligated rats and in gastric fistula rats. PACAP showed significant inhibitory effects on pentagastrin- and histamine-stimulated gastric acid secretion, but no effect on basal or carbachol-stimulated secretion in pylorus-ligated rats. It did show dose-related inhibitory effects both on basal gastric acid secretion and on secretion stimulated by pentagastrin, histamine, or carbachol in gastric fistula rats. PACAP did not alter serum gastrin levels. Inhibition of prostaglandin synthesis with indomethacin and immunoneutralization of somatostatin with anti-somatostatin serum did not prevent the inhibitory effect of PACAP on gastric acid secretion in pylorus-ligated rats. We conclude that PACAP most likely has a direct effect on parietal cells and that this effect may be mediated, at least partially, by inhibition of the action of histamine on parietal cells.

Somatostatin as a mediator of the effect of neurotensin on pentagastrin-stimulated acid secretion in rats.

Neurotensin and somatostatin have both been shown to inhibit gastric acid secretion, but no interaction between these peptides has been demonstrated. To determine whether somatostatin might be a mediator of neurotensin's effect on pentagastrin-stimulated gastric acid secretion, we performed the following three experiments. First, we collected 0.2-ml samples of portal venous blood as frequently as every 5 min, and we confirmed a significant release of somatostatin-like immunoreactivity into portal venous blood during neurotensin-induced inhibition of acid secretion. This release of somatostatin-like immunoreactivity and inhibition of acid secretion were only seen in pentobarbital-anesthetized rats, but no sustained release of somatostatin-like immunoreactivity or inhibition of acid secretion occurred in urethane-anesthetized animals. In the second experiment, we analyzed portal plasma by high pressure liquid chromatography, and found that portal somatostatin-like immunoreactivity in blood collected during neurotensin infusion was composed of a single peak corresponding to somatostatin-14. In the third experiment, we found that infusion of antibody to somatostatin prevented neurotensin from inhibiting pentagastrin-stimulated acid secretion. Taken together, these data show that somatostatin, possibly from the stomach itself, is a necessary mediator of neurotensin's inhibitory effect in pentobarbital-anesthetized rats.

HIV-1 gp41 antigen demonstration in esophageal ulcers with acquired immunodeficiency syndrome.

Esophageal ulcers associated with acquired immunodeficiency syndrome (AIDS) may be chronic, debilitating, and resistant to antifungal or antiviral therapy. The therapeutic management of these lesions remains controversial due to the difficulty in identifying pathogenic agent(s). We review previously published cases and describe three AIDS patients with esophageal ulcers that stained by immunoperoxidase techniques for human immunodeficiency virus (HIV)-1 surface glyloprotein (gp41). All three showed symptomatic resolution and healing of their ulcers with corticosteroid therapy. We believe this documentation of HIV-1 gp41 antigen within mononuclear cells of esophageal ulcers in AIDS supports a role of the HIV-1 virus in the pathophysiology of idiopathic esophageal ulcers in patients with AIDS. These cases further support a role for corticosteroid therapy in the treatment of esophageal ulcers resistant to antifungal and antiviral therapy in patients with AIDS.

Edematous pancreatitis associated with intravenous pentamidine.

A 37-year-old black man with presumed Pneumocystis carinii pneumonia who was treated with systemic IV pentamidine had fatal pancreatitis and massive hepatomegaly. Fatal pancreatitis can occur with no hemorrhagic changes seen at autopsy. Awareness of the relationship between pentamidine and pancreatitis should be emphasized. With current clinical trials testing other routes of administration, fatal complications associated with IV pentamidine therapy will be minimized.

Effect of pituitary adenylate cyclase activating polypeptide on rat pancreatic exocrine secretion.

A novel neuropeptide, pituitary adenylate cyclase activating polypeptide (PACAP), which has been isolated from ovine hypothalami, shows 68% homology with vasoactive intestinal peptide (VIP). Since VIP stimulates amylase secretion from the pancreas, we investigated the effect of PACAP and VIP on rat pancreatic exocrine secretion after intravenous injections of PACAP-27, PACAP-38, or VIP at doses of 2.5, 5 or 10 nmol/kg. Results showed: 1) Bolus injection of PACAP stimulated pancreatic amylase and protein secretions in a dose-dependent manner; and 2) Stimulation of amylase secretion with 10 nmol/kg of PACAP-27 was greater than that induced with the same dose of VIP or PACAP-38 (p less than 0.05).

Anesthetic dependence of the inhibitory effect of neurotensin on pentagastrin-stimulated acid secretion in rats. A possible role for somatostatin.

The existence of possible local mediators of the inhibitory effect of neurotensin on gastric acid secretion has not been determined. We perfused rats intragastrically with warmed saline and stimulated acid secretion with intravenous pentagastrin, 32 micrograms/kg/hr, and found that anesthesia with pentobarbital resulted in marked inhibition of acid secretion by intravenous neurotensin; however, anesthesia with urethane prevented this inhibitory effect of neurotensin from occurring. In addition, we found a significant increase in somatostatin-like immunoreactivity in portal venous blood during neurotensin infusion in pentobarbital-anesthetized rats. Neither neurotensin nor pentagastrin infusion modified gastric luminal somatostatin-like immunoreactivity after either pentobarbital or urethane, and rats anesthetized with urethane did not show an increase of somatostatin-like immunoreactivity in portal venous blood during neurotensin infusion. These results suggested that somatostatin-like immunoreactivity, released into the portal circulation, was necessary for exogenous neurotensin to inhibit pentagastrin-stimulated gastric acid secretion under these conditions in anesthetized rats.

Inhibitory effect of neurotensin on gastric acid secretion in rats. Development of a bioassay model.

Neurotensin has been shown to inhibit gastric acid secretion when administered in pharmacological doses, but no information has been available concerning its possible dose-related effect during intravenous infusion. In this study, a dose-related and reversible inhibitory effect of neurotensin was demonstrated in pentobarbital-anesthetized female Sprague-Dawley rats. The rats underwent continuous gastric perfusion with saline, 1 ml/min, and intravenous infusion of both pentagastrin and neurotensin. Inhibition of acid secretion did not depend upon the occurrence of hypotension, and ranged from 35 +/- 7% of maximal acid output at 0.24 nmol/kg/hr to 60 +/- 10% at 7.2 nmol/kg/hr of neurotensin. Blood levels of C-terminal neurotensin-like immunoreactivity were proportional to the dose of peptide infused and were 52 fmol/ml during infusion of 0.24 nmol/kg/hr, a dose that significantly inhibited pentagastrin-induced acid secretion. Thus, a model has been developed to study the effect of neurotensin infusion on acid secretion; the concentration of plasma neurotensin-like immunoreactivity at which inhibition occurs in this model is similar to the concentration reported to occur after a nutrient stimulus.

Local effect of neurotensin on canine ileal blood flow, and its release by luminal lipid.

This study was performed to determine whether the level of neurotensin in mesenteric venous blood after lipid perfusion is sufficient to establish neurotensin as a mediator of lipid-induced mesenteric vasodilation. In anesthetized dogs, arterial flow to segments of the ileum was recorded, and blood was collected for measurement of neurotensin-like immunoreactivity, and neurotensin and metabolites. Perfusion of the lumen with micellar lipid resulted in an increase in blood blow from 37.7 +/- 4.1 to 44.5 +/- 3.9 ml/min/100 g (p less than 0.01; n = 8); flow to a control segment did not change. Venous plasma neurotensin-like immunoreactivity doubled, and neurotensin also increased (to 11.3 +/- 3.9 fmol/ml; p less than 0.05). Close intra-arterial infusion of neurotensin at 5 pmol/min increased blood flow to 44.3 +/- 3.4 ml/min/100 g (p less than 0.025; n = 5); flow to a control segment did not change. Neurotensin-like immunoreactivity increased to the same extent as with lipid perfusion, and neurotensin increased to 28.6 +/- 6.1 fmol/ml (p less than 0.05). No accumulation of metabolites was detected in either experiment. Thus, infused neurotensin caused increased ileal blood flow at a level in venous plasma comparable to that present after lipid perfusion, suggesting that neurotensin may have a role in the local regulation of ileal blood flow.

Inhibitory effect of neurotensin on pentagastrin-stimulated gastric acid secretion in pylorus-ligated rats.

Neurotensin is a known inhibitor of gastrin-stimulated acid secretion in dogs and humans. In order to study the dose-related effect of neurotensin, we prepared pentobarbital-anesthetized rats by pyloric ligation and collected gastric secretions one hour after injection of saline (Basal), pentagastrin, 6 micrograms/Kg subcutaneously (PG Alone), or pentagastrin plus neurotensin by tail vein injection (PG + NT). Acid output was calculated from the volume and pH of the samples, which correlated well with the output determined by titration with 0.02 N NaOH (r = 0.92). Basal output was 36 +/- 4 muEq/hr; stimulated output (PG Alone) was 64 +/- 5 muEq/hr, and output after PG + NT, 250 pmol/Kg, was 33 +/- 3 muEq/hr (p less than 0.001). The effect of neurotensin was dose-related over a range from 125 to 500 pmol/Kg. This technique may be useful in the biological evaluation of neurotensin-related peptides.

Release and degradation of neurotensin during perfusion of rat small intestine with lipid.

The levels of neurotensin (NT) and its metabolite, the N-terminal octapeptide (NT1-8), identified by HPLC and measured by RIA, were increased in the hepatic-portal circulation of the anesthetized rat during perfusion of the small intestine with a lipid solution, while levels of both peptides remained unchanged in the general circulation. There was no significant arteriovenous difference for NT or NT1-8 during saline perfusion of the small intestine. Plasma collected from the superior mesenteric vein during the infusion of [3H]NT into the superior mesenteric artery showed major peaks of radioactivity with the retention times of NT1-8 and NT1-11 on HPLC. Only 12% of the radioactivity recovered from plasma was intact NT. These studies demonstrate that chromatographically identified NT and its metabolite, NT1-8, are elevated in the portal circulation but not systemic circulation during lipid perfusion and that the small intestine may be both the site of release and metabolism of NT.

Primary osteogenic sarcoma of the spine.

Primary osteogenic sarcoma of the spine is a rare tumor making up 0.85% to 2.0% of all osteogenic sarcomas. The majority (29/41) of previously reported cases have occurred in vertebrae affected by Paget disease or radiation exposure. Two cases of osteogenic sarcoma of the spine, one lumbar, the other thoracic, with no known predisposing factors are presented.

Clonal strains of rat medullary thyroid carcinoma cells that produce neurotensin and calcitonin. Functional and morphologic studies.

Strains of rat medullary thyroid carcinoma cells were established by two different techniques which were designed to ensure that clonal populations originated from single cells. The clonal strains (44-3C1 and 6-23C6) secreted both immunoreactive calcitonin (CT) and neurotensin (NT) and had growth characteristics that were similar to those of the parent cell lines. Both the 44-3C1 strain and the parent 44-2 cell line consistently produced more CT and NT than the 6-23C6 clonal strain or the parent 6-23 cell line. Peptide secretion in these clonal strains was stimulated by calcium and norepinephrine. Both clonal strains, similar to the parent lines, produced 4 to 12 times more NT than CT. Immunohistochemical studies showed that all cells in both clonal strains stained positively for CT. NT was also present in all cells from both strains with approximately 2% of the cells showing intense staining for this peptide. Ultrastructurally, the cells contained membrane-bound secretory granules which had a mean diameter of 95 nm. Secretory granules were relatively numerous in only 2% of the cells where they tended to be concentrated in cell processes. These studies demonstrate that single rat medullary thyroid carcinoma cells produce both CT and NT and that these strains are useful models for studies of NT and CT biosynthesis and for investigations of the regulation of secretion of two peptides from a single cell type.

The stability and metabolism of intravenously administered neurotensin in the rat.

The clearance and metabolism of synthetic and tritiated (3H) neurotensin (NT) were studied following its intravenous injection in a pharmacologic dose (500 pmol/kg) into anesthesized rats. Immunoreactive NT (iNT), measured in a radioimmunoassay (RIA) with use of a carboxyl-(C)-terminal directed antiserum, displayed an apparent half-life (t 1/2) of 0.55 min, while that measured by an amino-(N)-terminal directed antiserum had a t 1/2 of 5 min. The radiolabel from injected 3H-NT (3H on Tyr3,11) had a t 1/2 of 6.5 min. High-pressure liquid chromatography of extracts of plasma obtained from the circulation 0.5-3 min after injection of NT and 3H-NT showed the presence of NT and the generation mainly of the fragments NT1-8, NT1-11, and NT9-13, as well as free 3H-labeled tyrosine. The apparent half-lives of intravenously injected synthetic NT1-8, NT1-11 and NT1-12 measured with the N-terminal RIA were 9, 5 and 5 min, respectively, while that for NT9-13 was less than 0.5 min. These results indicate that exogenously injected NT is rapidly metabolized to form N-terminal fragments which are cleared more slowly than NT. These findings suggest that use of N-terminal antisera to detect the release of endogenous NT into the circulation is likely to yield measurements of the fragments NT1-8 and NT1-11 which thus far have been found to be biologically inactive.

Elevation of plasma neurotensinlike immunoreactivity after a meal. Characterization of the elevated components.

The detection of an elevation in neurotensinlike immunoreactivity in peripheral plasma for several hours after a meal has been confirmed and shown to be primarily due to the presence of aminoterminal fragments of neurotensin (NT) rather than to NT itself. We have developed a procedure to separate and characterize these N-terminal cross-reacting substances, and to estimate the contributions of these constitutents to plasma neurotensinlike immunoreactivity. Gel chromatography of pooled plasma extracts on Sephadex G-25 followed by reverse-phase high pressure liquid chromatography indicated that peptides coeluting with NT and its N-terminal partial sequences NT(1-8) and NT(1-11) were present in plasma. Comparison of plasmas collected before and 1 h after a defined meal, in five experiments, demonstrated no change in C-terminal immunoreactivity and an 8- to 10-fold rise in N-terminal immunoreactivity. Chromatographic analysis of pooled pre- and postmeal plasma in four experiments showed that essentially all of this elevation in neurotensinlike immunoreactivity measured with an N-terminal directed antiserum was due to increases in NT(1-8) and NT(1-11), while NT itself, measured using a C-terminal directed antiserum, did not increase appreciably in peripheral plasma 1 h after the meal. Generation of tritiated substances with the same elution times as NT(1-8) and NT(1-11) did occur after incubation of [(3)H]NT with whole blood in vitro, providing supporting evidence that these fragments are metabolites of NT. The marked elevation in the circulating levels of these fragments reflects that an increased secretion of NT occurred in response to the test meal. The secreted NT may have acted as a hormone before it was metabolized, or it may only have had a local (paracrine) effect.

Elevation of plasma neurotensin during lipid perfusion of rat small intestine.

Perfusion of the small intestine with a lipid solution results in elevated plasma neurotensin-like immunoreactivity in blood collected from the superior mesenteric vein. Perfusion of amino acids, glucose, hyperosmotic saline, acidified saline, bile salt and diluted rat bile had no effect. Neurotensin-like immunoreactivity in portal plasma was significantly higher than that measured concomitantly in peripheral arterial plasma. Neurotensin, as identified by high pressure liquid chromatography, rose from 4 to 9 fm/ml (n = 4) and 9 to 18 fm/ml (n = 9) extracted plasma during lipid stimulation as compared to the saline control. These results demonstrate that intraintestinal lipid is an effective and specific stimulus for the release of neurotensin from the small intestine into the portal circulation. However, until a target organ can be shown to respond to these modest levels of plasma neurotensin, it is unsettled whether the peptide is a hormone or whether its elevation in plasma is due to "overflow" of a paracrine agent.

Neurotensin in plasma: immunochemical and chromatographic character of acid/acetone-soluble material.

Using a RIA, we have examined the character of the neurotensin-like (NT-like) peptides present in acid/acetone extracts of animal and human plasma. Plasma immunoreactivity was measured using four antisera with different specificities. Antisera which were directed against the COOH-terminus of NT measured higher levels of plasma immunoreactivity than did antisera with NH2-terminal or mixed specificity. Chromatographic fractionation of bovine plasma extracts revealed the presence of multiple substances, one of which was chromatographically and immunochemically indistinguishable from NT. We estimate the plasma level of this component to be about 15-25 fmol/ml, which is 30-50% of the measurement obtained on unfractionated extracts using antiserum HC-8. Several other components were also identified which behaved as though they were smaller than NT and seemed to share with NT four to eight of its COOH-terminal amono acids. One eluted from Sephadex G-25 in the region of the NT-like peptide previously identified in extracts of gastric mucosa. Infusion of synthetic NT into rats for 30 min did not result in the formation of these COOH-terminal relatives of NT. Our results argue strongly for the presence of NT in plasma and also indicate that other peptides, sharing COOH-terminal homologies with NT, appear in plasma, possibly from the stomach, liver, and other as yet unidentified source(s).

Characterization of neurotensin production by a line of rat medullary thyroid carcinoma cells.

The rMTC 6-23 cell line was derived from a calcitonin-producing rat medullary thyroid carcinoma. During characterization of these cells we discovered that they also synthesize and secrete neurotensin (NT), a tridecapeptide originally isolated from the hypothalamus and not previously associated with C cells. Immunoreactive NT (iNT) was measured with two antisera: HC-8, which recognizes the COOH-terminal eight amino acids, and TG-1, which binds the NH2-terminal region of NT. By use of these antisera, 2 M acetic acid extracts of rMTC 6-23 cells were found to contain 0.7--5.0 pmol of iNT per mg of cell protein. Successive fractionation of iNT from cell extracts by gel filtration, ion-exchange chromatograpy, and reverse-phase high-pressure liquid chromatography showed at each step a peak of iNT that was indistinguishable from synthetic NT in its chromatographic behavior. Biologic activity of the iNT was confirmed by demonstrating the characteristic fall in arterial blood pressure in the rat after intravenous injection of material purified from rMTC 6-23 cells. Calcium (0.5--4.0 mM) stimulated release of iNT in a dose-dependent manner; the effect was maximal at 3--4 mM calcium. K+ (50 mM) stimulated release of iNT that was maximal in the presence of 1.0--1.5 mM calcium. Synthesis and secretion of iNT by these cells were shown during a 16-day growth experiment. These results demonstrate that rMTC 6-23 cells contain NT and suggest the possibility of an association between neurotensin and calcitonin.

Isolation of human intestinal neurotensin.

The biologically active peptide neurotensin (NT) has been isolated from fresh postmortem human small intestine and its identity with bovine hypothalamic and intestinal neurotensin has been established. Purification was achieved by gel filtration and two ion exchange chromatography steps; material was detected by radioimmunoassay (RIA). A substance was obtained that had integral molar ratios of amino acids and eluted in a single peak during reverse-phase high pressure liquid chromatography (HPLC). This material had an amino acid composition and COOH-terminal sequence identical with those of bovine NT. Human and bovine neurotensin gave rise to the same fragments when treated with papain; they were indistinguishable in RIAs using three different region-specific antisera and in their hypotensive effect on anesthetized rats. Using mucosal scrapings obtained immediately post-mortem from four subjects, the concentration of immunoreactive neurotensin was found to increase from duodenum to distal ileum, in agreement with results obtained in other mammalian species.