Plasma glucagon-like immunoreactivity (GLI) in dogs.

Gut glucagon-like immunoreactivity (GLI) was extracted from plasma of dogs and was compared for its molecular size and insulin releasing activity with GLI present in the intestine. Plasma was obtained from the portal vein of dogs, of which the pancreas was removed as rapidly as possible during the glucose administration into the intestine. Plasma GLI of intestinal origin was extracted by a modification of Kenny's method. The amount of GLI extractable from plasma in each dog ranged from 4.30 to 25.74 ng. The extract of plasma during glucose absorption was observed to have two peaks on gel filtration, corresponding to Peak I and Peak II of GLI extracted from the gastrointestinal tract. The intrapancreatic infusion of the Peak II GLI extractable from plasma promoted remarkable insulin release in dogs, like pancreatic glucagon. In contrast, the Peak I GLI from plasma caused an equivocal rise of insulin in the pancreatic vein. It is concluded from the experiment that gut GLI extracted from plasma shows the same elution pattern on gel filtration and the same insulin releasing activity as GLI extractable from the gut.     

Measurements of somatostatin-like immunoreactivity in plasma

The validity of measurements of somatostatin-like immunoreactivity (SLI) in canine plasma has been examined. The radioimmunoassay employed had a minimal sensitivity of 50 pg/ml and a discriminatory sensitivity of 15 pg/ml above this. The coefficient of variation within and between assays was 6% and 18%, respectively. There was no cross-reaction with any of 9 other peptide hormones tested. Significant incubation damage by canine plasma to the [¹²⁵I]-tyrosine¹-somatostatin tracer was effectively prevented by Trasylol and EDTA, and recovery of synthetic somatostatin added to canine plasma and incubated for 3 h at 20°C was 96%. Subcutaneous injections of somatostatin were followed by a prompt rise in plasma SLI that was significantly correlated with decrease in plasma glucagon levels. Serial dilutions of plasma specimens containing high levels of either endogenous SLI or injected synthetic somatostatin gave proportional readings and their slopes paralleled those of synthetic somatostatin in plasma-free buffer. Ninety-five percent of endogenous plasma SLI was removed by passage of plasma specimens through a column of immobilized somatostatin antibodies. Both endogenous SLI in plasma and synthetic somatostatin added to plasma were eluted in the void volume of Biogel P-10 columns, but following isolation by affinity chromatography the molecular size of both was approx. 1600, suggesting that both endogenous SLI and synthetic somatostatin circulate in plasma bound to larger molecules. It is concluded that this radioimmunoassay permits valid measurements of endogenous SLI in canine plasma.     

Increased urinary atrial natriuretic peptide-like immunoreactivity excretion but decreased plasma atrial natriuretic peptide concentration in patients with hyperosmolar-hyperglycemic nonketotic syndrome.

OBJECTIVE: This study was undertaken to measure urinary atrial natriuretic peptide-like immunoreactivity (ANP-LI) and plasma ANP concentration in patients with hyperosmolar-hyperglycemic nonketotic syndrome (HHNS) to investigate the change of renal ANP-LI and cardiac ANP synthesis in volume-depleted diabetic patients. RESEARCH DESIGN AND METHODS: The urine ANP-LI:creatinine ratio, plasma ANP level, and plasma renin activity (PRA) were measured in 12 patients with HHNS during the acute stage and after recovery, in 28 oral hypoglycemic agent (OHA)-treated type 2 diabetic patients, and in 23 normal subjects. ANP and PRA were measured by radioimmunoassay. RESULTS: These HHNS patients had severe hyperglycemia and hyperosmolality as well as increased blood urea nitrogen, creatinine, and PRA levels, as compared with normal subjects and OHA-treated type 2 diabetic patients. In these patients, the urinary ANP-LI:creatinine ratio (11.69 +/- 2.11 pmol/mmol) was significantly increased in comparison with the normal group (1.78 +/- 0.11 pmol/mmol) and OHA-treated diabetic patients (2.43 +/- 0.45 pmol/mmol), whereas plasma ANP concentration (5.12 +/- 0.72 pmol/l) was significantly lower than the corresponding values of the normal group (7.39 +/- 0.85 pmol/l) and OHA-treated diabetic patients (8.43 +/- 1.05 pmol/l). All of these abnormalities were significantly ameliorated after insulin, fluid, and electrolyte replacement. CONCLUSIONS: Our data show that urinary ANP-LI was significantly increased, whereas plasma ANP concentration was decreased, in the face of raised PRA in HHNS patients. This study indicates that renal ANP-LI substances and cardiac ANP may exhibit different responsiveness in diabetic patients with HHNS.     

Increased pulmonary neuroendocrine cells with bombesin-like immunoreactivity in adult patients with eosinophilic granuloma.

Cigarette smoking is associated with hyperplasia of pulmonary neuroendocrine cells and variably increased levels of bombesin-like peptides in the lower respiratory tract. Because the neuropeptide bombesin is a chemoattractant for monocytes and a mitogen for 3T3 fibroblasts, we hypothesized that an excess of neuroendocrine cells and bombesin-like peptides could contribute to lung inflammation and fibrosis in certain cigarette smokers. Eosinophilic granuloma is a fibrotic lung disease of unknown etiology that in adults occurs almost invariably in cigarette smokers. We quantitated neuroendocrine cells with bombesin-like immunoreactivity in open lung biopsies from patients with eosinophilic granuloma (n = 6) and compared these with cigarette smokers (n = 6) who underwent lung resection for reasons other than primary lung disease. In addition, we compared them with patients with idiopathic pulmonary fibrosis (n = 8), a disease not associated with cigarette smoking. Finally, we also examined the mitogenic effect of bombesin on cultured human adult lung fibroblasts. The patients with eosinophilic granuloma exhibited a 10-fold increase in neuroendocrine cells with bombesin-like immunoreactivity compared to both smokers (P = 0.005) and patients with idiopathic pulmonary fibrosis (P = 0.005). In addition, bombesin produced a significant mitogenic effect on cultured human adult lung fibroblasts at concentrations of 1 nM and above. We conclude that increased numbers of pulmonary neuroendocrine cells with bombesin-like immunoreactivity are commonly found in patients with eosinophilic granuloma and, since bombesin-like peptides are chemotactic for monocytes and mitogenic for human lung fibroblasts, we speculate that neuroendocrine cell hyperplasia may be important in the pathogenesis of eosinophilic granuloma in adult cigarette smokers.     

Increased plasma fibronectin concentration in diabetic patients with microalbuminuria

Raised levels of plasma fibronectin (PF), an alpha 2-glycoprotein produced by vascular endothelia, have been previously described in diabetic patients with retinopathy and overt nephropathy. The aim of this study was to investigate whether the presence of microalbuminuria is associated with increased PF concentrations. Twenty Albustix-negative diabetic outpatients with microalbuminuria [median albumin excretion rate (AER): 30.2 micrograms/min; range 12.1-194 micrograms/min] were compared with 58 sex- and age-matched patients without microalbuminuria (median AER 3.1 micrograms/min; range 0.8-12 micrograms/min) and 34 control subjects (median AER 2.8 micrograms/min; range 0.8-12.1 micrograms/min). Mean PF was significantly higher in the group with microalbuminuria (406.7 +/- 85.5 micrograms/ml) than in the group without it (325.3 +/- 76.5 micrograms/ml or in control subjects (334.5 +/- 76 micrograms/ml; P less than .05). PF increase associated with microalbuminuria was independent of the presence of retinopathy. Furthermore, in the whole group of diabetic patients, PF was significantly correlated with AER (r = .33; P = .003). Such correlation also remained significant (P = .0002) after covariance analysis by a stepwise discriminant procedure taking into account age, duration of disease, sex, blood pressure, body weight, therapy, and HbA1. In conclusion, PF increase is associated with microalbuminuria independent of the other considered variables; its role as a possible marker for early diabetic nephropathy remains to be fully clarified.     

Increased plasma endothelin in NIDDM patients with retinopathy.

OBJECTIVE--To elucidate the significance of ET in diabetic microvascular disease. RESEARCH DESIGN AND METHODS--We determined plasma levels of ir-ET-1 in 25 NIDDM patients without hypertension and/or renal dysfunction. RESULTS--The plasma levels of ir-ET-1 in NIDDM patients with simple (n = 8) and proliferative (n = 8) retinopathy were 0.58 +/- 0.04 pM and 0.60 +/- 0.04 pM, respectively, which were significantly higher than those in normal, nondiabetic subjects (0.24 +/- 0.02 pM [n = 31]) and NIDDM patients without retinopathy (0.30 +/- 0.05 pM [n = 9]). CONCLUSIONS--These results suggest that plasma ET-1 is related to diabetic microvascular disease.     

Nonlinear intestinal first-pass metabolism of salicylamide in dogs after portacaval transposition

The dose-dependent first-pass metabolism and pharmacokinetics of salicylamide (SAM) were studied at four dose levels in dogs before and after portacaval transposition. Four minutes after each p.o. dose, a tracer dose of [14C]SAM was given i.v. to determine clearance and bioavailability. Over the dosage range studied pretransposition, 5 to 40 mg/kg, bioavailability increased from 0.24 +/- 0.14 (mean +/- S.D.) to 0.76 +/- 0.20 (P less than .05). Clearance decreased from 3.4 +/- 1.0 to 0.6 +/- 0.11 liter/min (P less than .01) and half-life increased from 5.0 +/- 1.2 to 23.5 +/- 6.1 min (P less than .01). Over the dosage range studied post-transposition, 1.5 to 20 mg/kg, bioavailability increased from 0.31 +/- 0.09 to 0.99 +/- 0.08. Clearance and half-life had the same values and showed the same dose-dependence as in the normal dogs. The amount of SAM removed by the intestine during first-pass remained constant at about 1 mg/kg over the dose range given to the post-transposition animals. Therefore, although more easily saturable than the liver, the intestine plays an important role in first-pass metabolism of low p.o. doses of SAM. In contrast to previous results in the normal dog, the p.o. coadministration of sodium sulfate did not reduce the bioavailability of SAM in transposed dogs. This indicates that the nonlinear intestinal first-pass metabolism of SAM is not due to the depletion of the cosubstrate precursor, inorganic sulfate.     

Snapshots in surgery: small bowel intussusception following ileojejunal bypass

Jejunal intussusception is a known complication of ileojejunal bypass surgery for obesity that may present as an acute abdomen. It can be avoided if the jejunum is anchored to the transverse mesocolon intra‐operatively.     

Characterization of the responses of circulating glucagon-like immunoreactivity to intraduodenal and intravenous administration of glucose

The effects of ingested and infused glucose upon circulating glucagon-like immunoreactivity (GLI) were compared in 14 triply catheterized conscious dogs. Within 60 min after the intraduodenal administration of 2 g/kg of glucose, the mean level of glucagon-like immunoreactivity in the vena caval plasma more than doubled, whereas after intravenous infusion of the same dose over a 90 min period no change in the mean vena caval level was observed; during glucose infusion mean glucagon-like immunoreactivity in the pancreatic venous effluent declined, suggesting that hyperglycemia suppresses rather than stimulates pancreatic glucagon secretion.To determine if the rise in glucagon-like immunoreactivity that occurs during glucose absorption was of pancreatic origin, the effect of pancreatectomy performed 1 hr after the intraduodenal administration of glucose was determined. Although circulating insulin disappeared after resection of the pancreas, the level of glucagon-like immunoreactivity continued to rise, establishing its extrapancreatic origin. In other experiments, measurements of Glucagon-like immunoreactivity in plasma obtained simultaneously from pancreaticoduodenal and mesenteric veins and from the vena cava revealed the increment after intraduodenal glucose loading to be greatest in the mesenteric vein in 8 of 12 experiments, favoring the gut as the likely source of the rise.To characterize gut glucagon-like immunoreactivity, acid-alcohol extracts of canine jejunum were compared with similar glucagon-containing extracts of canine pancreas with respect to certain physical and biological properties. On a G-25 Sephadex column the elution volume of the jejunal immunoreactivity was found to be smaller than that of glucagon, which suggested a molecular size at least twice that of pancreatic glucagon. Furthermore, the in vivo and in vitro biological activities of the eluates containing jejunal glucagon-like immunoreactivity appeared to differ from those of eluates containing pancreatic glucagon. The jejunal material lacked hyperglycemic activity when injected endoportally into dogs, was devoid of glycogenolytic activity in the isolated perfused rat liver, and did not increase hepatic 3',5' cyclic adenylate in the perfused liver; however, like glucagon it appeared to stimulate insulin release. It seems quite clear the material in intestinal extracts either is a different substance or a different form from that of true pancreatic glucagon, although it crossreacts in the radioimmunoassay with antibodies to glucagon.It is concluded, (a) that hyperglycemia does not stimulate and probably suppresses the secretion of pancreatic glucagon; (b) that during intestinal absorption of glucose, a rise in glucagon-like immunoreactivity occurs; (c) this immunoreactivity is derived from an extrapancreatic site, probably the gut; (d) that the glucagon-like immunoreactivity extractable from jejunum is not the same as pancreatic glucagon but is a larger molecule devoid of hyperglycemic and glycogenolytic activity, a cross-reactant in radioimmunoassay for glucagon; and (e) that the eluate in which jejunal immunoreactivity is contained can stimulate insulin release in conscious dogs.     

Effect of ileo-jejunal transposition on intestinal adaptation after total colectomy in dogs

The effect of ileo-jejunal transposition (IJT) on the intestinal adaptation after total colectomy was investigated in 4 mongrel dogs. Hyperenteroglucagonemia was observed in the IJT with colectomy group, especially in postprandial state. Obvious hyperplastic changes were observed in all part of the small intestinal mucosa in the colectomy with IJT group. However, there were no significant differences in body weight changes between the colectomy with IJT group and the colectomy group. Postprandial plasma gastrin levels were lower in the colectomy with IJT group compared to the control. These results suggest that IJT causes hyperenteroglucagonemia and intestinal mucosal hypertrophy in colectomized dogs. Enteroglucagon may have an inhibitory effect on postprandial gastrin release.     

Increased plasma noradrenaline and serum gastrin in patients with duodenal ulcer

Serum gastrin, serum insulin, plasma noradrenaline, plasma adrenaline, pulse rate and blood pressure were measured repeatedly during 24h in six patients with duodenal ulcer and in six control subjects. Mean serum gastrin concentration was 3-4 times higher in duodenal ulcer patients than in controls during both the day and at night. Serum insulin was the same in both groups of subjects. Overnight fasting and mean supine plasma noradrenaline as well as mean supine pulse rate were significantly higher in duodenal ulcer patients than in controls. Plasma adrenaline and arterial blood pressure were the same in patients and controls. These results suggest that sympathetic nervous activity is increased in patients with duodenal ulcer. The increased sympathetic nervous activity may mean that duodenal ulcer patients are subject to more stress than normal subjects or may be compensatory to increased vagal nervous activity presumed by some authors to be present in such patients.     

Increased plasma biotinidase activity in rats with paracetamol-induced acute liver injury

BACKGROUND: Biotinidase, an enzyme that is synthesized by the liver and secreted into the blood, decreases in plasma in both humans and experimental animal liver cirrhosis. In overdose conditions, paracetamol is known to cause centrilobular necrosis in both humans and experimental animals. We determined if there is any alteration in the activity of the enzyme in the plasma and liver of rats after subtoxic and toxic doses of paracetamol. METHODS: After 4-, 24-, and 40-h treatment of rats with either subtoxic (350 mg/kg body wt) or toxic dose (1000 mg per kg) of paracetamol intraperitoneally, biotinidase activity was assayed in the liver and plasma along with the albumin concentration and ALT activity. RESULTS: After the subtoxic dose of paracetamol, there were no significant change in plasma biotinidase activity and liver biotinidase activity was observed at any time period after treatment. However, 24 and 40 h after the toxic dose of paracetamol, biotinidase activity was decreased in the liver and increased in the plasma as compared with the control, when plasma ALT was increased. CONCLUSION: The increase in plasma biotinidase activity may serve as an indicator of paracetamol-induced acute liver injury in the rat.     

Increased thrombomodulin values in plasma of diabetic men with microangiopathy.

To study the significance of plasma thrombomodulin (TM) values in diabetes mellitus, we determined plasma TM in 34 patients with non-insulin-dependent diabetes mellitus (NIDDM) men, mean age 54 (SE 2) years. Plasma TM was determined by an enzyme immunoassay with anti-TM monoclonal antibodies. The plasma TM values were significantly greater in NIDDM patients with nephropathy than in patients without nephropathy (P less than 0.001). Also, a significant positive correlation was noted between the concentration of plasma TM and serum creatinine (r = 0.55, P less than 0.001). The plasma TM values of the patients with retinopathy were significantly greater than the values of those without it (P less than 0.002). Furthermore, we noted a significant positive correlation (r = 0.78, P less than 0.001) between plasma TM and the severity of diabetic retinopathy as graded by Scott's classification. These results suggest a close relationship between TM and diabetic microangiopathy.