Histology of the intestinal peritoneum in patients with cirrhosis of the liver and ascites

Portal hypertension and hypoalbuminemia are usually incriminated in the development of ascites in liver cirrhosis, and altered peritoneal permeability is considered only as a hypothetical possibility. Jejunal postmortem specimens were studied in 15 control patients and 16 patients dying with cirrhosis of the liver and ascites. In decompensated cirrhosis a fibrous thickening of the peritoneum was found, 159.0±96.4 m (mean±sd) compared to 24.5±10.6 m in controls (P<0.001). An increase in the size and number of blood vessels, lymphangiectasiae, and mononuclear cell infiltration were invariably present. These histological changes are consistent with a nonspecific chronic peritonitis. The findings indicate there is increased blood perfusion and lymph flow within the intestinal peritoneum in patients with decompensated cirrhosis of the liver and support the existence of an intestinal peritoneal factor in the pathogenesis of cirrhotic ascites.     

Portal hypertensive colopathy

The aim of this paper was, first, to show in a case control study that in alcoholic cirrhotic patients colonic vascular ectasias (VE) are a complication of portal hypertension and, second, to establish in a histomorphometric study that colonic vascular ectasias and rectal varices (RV) are only endoscopic features of a new entity: portal hypertensive colopathy, the pathologic basis of which is colonic mucosal capillary ectasia. In the case control study, for each case, three age- and sex-matched controls selected from consecutive patients were used. Sixteen alcoholic cirrhotic patients, 12 men, 4 women (mean age ±sd: 62±10 years) had colonic vascular ectasias. The prevalence of esophageal varices (88% vs 44%,P<0.005), esophageal varices (5 mm) (44% vs 12.5%,P<0.01), previous history of bleeding from esophageal varices (44% vs 8%,P<0.005), and rectal varices (63% vs 6%,P<0.001) was significantly greater in cases with colonic vascular ectasias than in controls without colonic vascular ectasias. The relative risk of colonic vascular ectasias in alcoholic cirrhotic patients with esophageal varices versus cirrhotic patients without esophageal varices was 14.4 (95% confidence interval 2.8–75.3). In the histomorphometric study, cirrhotic patients with vascular ectasias and/or rectal varices had a significantly higher mean diameter of vessels (20.3±1.5 m vs 18.7±1.6 m,P<0.05) and a higher mean cross-sectional vascular area (2143±396 m² vs 1676±345 m²,P<0.05) than cirrhotic patients without vascular ectasias and/or rectal varices. These results suggest that colonic vascular ectasias seem to be a complication of portal hypertension and that colonic vascular ectasias and rectal varices are endoscopic features of a new entity the portal hypertensive colopathy.     

Hemodynamic Effects of Eight-Day Octreotide and Propranolol Administration in Portal Hypertensive Rats

Octreotide and propranolol are both effective portal hypotensive drugs in the control or prevention of variceal bleeding. The present study was undertaken to investigate the hemodynamic effects of octreotide and propranolol, alone or in combination, in portal hypertensive rats. Portal hypertension was induced by partial portal vein ligation. Portal hypertensive rats were allocated into one of the four groups: vehicle group (saline, 0.5 ml/day), octreotide group (100 g/kg/12 hr), propranolol group (30 mg/kg/day), and octreotide (100 g/kg/12 hr) plus propranolol (30 mg/kg/day) group. Propranolol or saline was administered by gavage, octreotide by subcutaneous injection. Drug was given one day before ligation and continued for eight consecutive days. Systemic as well as splanchnic hemodynamic parameters were measured thereafter. The portal venous pressure, portal tributary blood flow, and cardiac index were significantly reduced by octreotide, propranolol, or octreotide plus propranolol in portal hypertensive rats. Portal territory, systemic, and renal vascular resistances were significantly enhanced, while hepatic arterial blood flow significantly reduced, in the octreotide and octreotide plus propranolol groups as compared to vehicle group. Our results showed that eight-day administration of octreotide, propranolol, or octreotide plus propranolol led to portal hypotensive and antihyperdynamic effects in portal hypertensive rats. Overall, octreotide treatment alone resulted in better antihyperdynamic profiles than propranolol treatment alone. The combination of octreotide and propranolol offered no therapeutic benefits and was slightly less effective than octreotide alone.     

Exogenous hyperglucagonaemia in insulin controlled diabetic rats increases urea excretion and nitrogen loss from organs

Summary In order to study the effect of hyperglucagonaemia on nitrogen metabolism in diabetes, zinc protamin glucagon 60 g was injected subcutaneously 3 times daily for 4 weeks into streptozotocindiabetic rats (n=5), adequately treated with long acting insulin. This raised the plasma concentration of glucagon to 725±125 (mean±SEM), which is not different from that found in portal blood of uncontrolled diabetic rats: 400±75 ng/l. The controls were 5 diabetic rats treated with insulin alone and 5 non-diabetic rats.Compared with control rats the nitrogen balance was reduced (p<0.05) and the nitrogen contents of carcass, heart, intestines, and kidneys were reduced by 15–30% (p<0.05) in the glucagon treated rats. The hepatic capacity of urea synthesis and the alanine elimination rate were determined in the 3 above-mentioned groups, and confirmed in 3 identical groups followed for only 2 weeks; and in addition in a group of glucagon treated diabetic rats, where the long acting glucagon was substituted by neutral insulin the last two days before investigation. The capacity of urea-N synthesis and the alanine elimination rate were, respectively, in control rats: 9.6±0.8 and 5.9±0.3 mol/(min 100 g body weight), in insulin treated diabetic rats: 8.5±0.7 and 5.4±0.6 mol/(min 100g body weight), in glucagon treated rats: 6.3±0.4 (lower than controls, p<0.05) and 10.4±0.4 (higher than controls, p<0.05) (mol/(min 100 g body weight), and in glucagon treated rats given neutral insulin: 20.7±1.6 and 10.9±0.3 mol/(min 100 g body weight) (both higher than controls, p<0.05). Hyperglucagonaemia in itself leads to loss of nitrogen from organs, probably by an increased hepatic conversion of amino-nitrogen to urea-nitrogen, as evidenced by the increased urea excretion. This proceeds despite an insulin induced decrease in the capacity of urea synthesis and may thus rather be attributed to changes in the affinity of urea synthesis for amino-nitrogen.     

Neurally-mediated vasodilatation in normal and portal hypertensive rats: role of nitric oxide and calcitonin gene-related peptide

Background/Aims: Portal hypertension is associated with systemic vasodilatation and vascular hyporeactivity, and is reversed by inhibiting nitric oxide biosynthesis. Nitric oxide and calcitonin gene-related peptide are neurotransmitters of non-adrenergic non-cholinergic nerves. The role of nitric oxide and calcitonin gene-related peptide in nerve-stimulated vasodilatation in portal hypertension is unknown.Methods: We tested (i) if in vitro perfused superior mesenteric arterial vascular beds of portal hypertensive rats (induced by partial portal vein ligation) showed an increased vasodilatation to periarterial nerve stimulation compared to normal controls, and (ii) if this vasodilatation was modulated by nitric oxide and calcitonin gene-related peptide antagonism.Results: Vasodilatatory responses to periarterial nerve stimulation (10 V, 1 ms) with increasing frequencies (Hertz, 2–12) in preconstricted vessels (methoxamine and guanethidine) were significantly smaller in vessel preparations of control (n=8) compared to portal hypertensive (n=7) rats, values with 8 Hertz being 32.3±3.6% and 44.9±3.6%, respectively (p<0.05). This difference was reversed by inhibiting nitric oxide and calcitonin gene-related peptide action with the nitric oxide-biosynthesis inhibitor N^ω-Nitro-L-arginine, values for 8 Hertz being 28.7±4.8% (controls) and 37.8±3.3% (portal hypertensive, ns) or with the calcitonin gene-related peptide antagonist CGRP_8–37, values being 25.2±2.8% (controls) and 27.8±4.2% (portal hypertensive, ns), respectively (n=4–6 per group). Vasodilatation to the β-agonist isoproterenol was not significantly different between groups with and without calcitonin gene-related peptide and nitric oxide antagonism.Conclusion: Portal hypertensive rats display a significantly enhanced vasodilatation to periarterial nerve stimulation, which is reversed by inhibiting the non-adrenergic non-cholinergic neurotransmitters nitric oxide and especially calcitonin gene-related peptide.     

Effects of Octreotide on Intestinal Transit and Bacterial Translocation in Conscious Rats with Portal Hypertension and Liver Fibrosis

In cirrhosis, delayed intestinal transit may be responsible for increased endoluminal bacterial overgrowth and increased bacterial translocation. Octreotide has been reported to reduce intestinal transit. Therefore, we evaluated whether octreotide administration influences bacterial translocation in a model of liver fibrosis secondary to dimethylnitrosamine (DMNA) administration. Twenty-nine conscious rats were randomly assigned to three groups (sham rats + placebo as controls, DMNA + placebo, DMNA + octreotide, 1.5 g/kg thrice daily subcutaneously), and including portal pressure, intestinal transit (radioactive method), and bacterial translocation were measured. Three of four variables measuring intestinal transit suggested a significant delay in intestinal transit in DMNA rats compared to controls (eg, cumulated radioactivity 50%: controls: 5.3 ± 1.5, DMNA + placebo: 3.2 ± 1.2, DMNA + octreotide: 2.7 ± 1.9, P < 0.01). This delay tended to be enhanced by octreotide but the effect was only significant with one of the intestinal transit variables. Bacterial translocation was significantly increased in DMNA rats compared to controls but octreotide did not increase translocation [eg, germ count (log) in lymph nodes: controls: 3.1 ± 3.6, DMNA + placebo: 12.3 ± 4.4, DMNA + octreotide: 10.6 ± 6.0, P < 0.001]. There was no significant correlation of portal pressure, intestinal transit, and bacterial translocation in this study. In conclusion, our results show that, although octreotide worsens delayed intestinal transit, it has no influence on the level of bacterial translocation.     

Gastric diversion or pylorus ligation for gastric mucosal integrity and acid secretion studies in the rat?

The advantages of gastric diversion over pylorus ligation in rat gastric mucosal integrity and acid secretion studies over 6 hr were investigated. Mucosal injury developed in 80% of pylorus-ligation controls. Atropine (5 mg/kg) or cimetidine (40 mg/kg) had no effect on this injury (2.9 mm²±0.9 and 2.8 mm²±0.7, respectively, vs 3.1 mm²±1, mean±sem, N=10; however vagotomy increased it (13.7 mm²±Pylorus-ligation H⁺ output was higher than that of gastric diversion (390.5 mol±54.8 vs 61 mol±2.5, mean±sem, N=10, P<0.001). Cimetidine (40 mg/kg) depressed H⁺ output of gastric diversion (21.3 mol±1.2 vs 61 mol±2.5, mean±sem, N=10, P<0.001), but not of pylorus ligation (424 mol±74.2 vs 390.5 mol±54.8, mean±sem, N=10). Vagotomy or atropine depressed pylorus-ligation H⁺ output (P<0.001), but each allowed an output (36.6 mol±5.5 and 120 mol±29, respectively, mean±sem, N=10) significantly (P<0.001) higher than that associated with it in gastric diversion (16 mol±1.4 and 17.1 mol±1.6, respectively, mean±sem, N=10). This study demonstrates that in the rat pylorus ligation, in contrast to gastric diversion, injures the gastric mucosa, stimulates H⁺ secretion, and overshadows the efficacy of antisecretory agents.     

16,16-Dimethyl prostaglandin E2 induces villus contraction in rats without affecting intestinal restitution

In a previous study we found that 16,16-dimethyl prostaglandin E2 protects the small intestine against chenodeoxycholic acid injury in the rat. One possible explanation for prostaglandin's protective action may be that prostaglandin-induced villus contraction accelerates mucosal restitution. This hypothesis was tested in rats by perfusing intestinal segments in vivo in a single-pass fashion with 0.125-0.5 micrograms/L of 16,16-dimethyl prostaglandin E2. These studies showed a dose-dependent, reversible contraction of intestinal villi and crypts. To test the effect of this contraction on mucosal restitution, standardized intestinal injury was produced in indomethacin-pretreated rats perfused in vivo with 5 mmol/L chenodeoxycholic acid. The rats were then perfused with bile acid-free buffer containing either 0.5 microgram/mL of 16,16-dimethyl prostaglandin E2 or vehicle. This study showed that despite decreasing villus height after bile acid injury, 16,16-dimethyl prostaglandin E2 did not significantly affect the rate of morphologic (assessed by villus denudation) or functional (assessed by mannitol and water absorption) restitution of the injured intestinal mucosa. Thus, although 16,16-dimethyl prostaglandin E2 causes villus contraction, this effect does not result in more rapid restitution of the injured intestinal mucosa and is not a likely mechanism for prostaglandin-mediated protection of the intestinal mucosa.     

Impaired Adaptive Cytoprotection to Ethanol-Induced Damage in Gastric Mucosa of Portal Hypertensive Rats

Portal hypertension predisposes gastric mucosato increased damage by noxious agents. Adaptivecytoprotection has not been studied in portalhypertensive gastric mucosa. We evaluated adaptivecytoprotection in the gastric mucosa of portal hypertensiverats by exposure to ethanol. The injury index (percentgross lesions) was significantly higher in portalhypertensive rats than in sham-operated rats. The ratio of adaptive cytoprotection, calculated as thedegree of decrease in the injury index caused bypre-absolute-ethanol administration of 20% ethanol, wassignificantly impaired in portal hypertensive rats. Basal levels of gastric mucosal hexosamine werelower in portal hypertensive rats than in controls, anda blunted response to 20% ethanol was associated withportal hypertension. Nitric oxide inhibition (L-NAME, 5 mg/kg) reduced the ratio of adaptivecytoprotection in sham-operated but not in portalhypertensive rats. These results suggest that impairedadaptive cytoprotection in portal hypertensive gastric mucosa may be caused by blunted mucusproduction.     

Islet B-cell dysfunction and the time course of recovery following chronic overinsulinisation of normal rats

Summary Appropriate insulin therapy may preserve or improve islet B-cell function whereas the effects of overinsulinisation are unclear. Pancreatic islet B-cell function was therefore studied after overinsulinisation of normal rats for 4 weeks (fed blood glucose 2.2–4.5 mmol/l, controls 4.1–7.0 mmol/l). Insulin secretion was assessed by a 3-h hyperglycaemic clamp (10.0 mmol/l) performed 1, 48, and 120 h after insulin withdrawal (n=6 in each group). When the clamp was performed 1 h after insulin withdrawal, clamp insulin concentration was 1.6±0.1 g/l, compared to 9.3±1.0 g/l in control rats. The integrated area under the plasma insulin concentration curve was also significantly decreased (4.8±0.4 vs 20.3±2.2 g·l^–1·h^–1, p<0.001), but recovered to 9.4±1.0 g·l^–1·h^–1 after 48 h, and to 17.5±1.4 g·l^–1·h^–1 after 120 h. Pancreatic insulin contents were decreased at 1 h (6±1 g/g wet wt) and 48 h (54±12 g/g wet wt) but not at 120 h (221±30 g/g wet wt) after withdrawal (controls, 303±29 /g wet wt) and there was a strong relationship with pancreatic preproinsulin mRNA and the clamp insulin response. Thus, overinsulinisation with prolonged periods of low blood glucose concentrations impairs islet B-cell function, but is reversible over 5 days.     

An evaluation of urinaryd-glucaric acid excretion during acute hepatitis in man

The excretion of urinaryd-glucaric acid (d-GA), one of the final metabolites of glucuronic acid was determined in 49 patients with acute hepatitis. A 3.7-fold increase ofd-GA was found at an early stage of the disease (37.13 mol/24hr±3.08se vs 9.91 mol/24hr±1.18se in normal controls), when serum transaminases and bilirubin were very high (SGOT 589 I.U.±41se; SGPT 954 I.U.±61se; serum bilirubin 8.41 mg/100 ml±0.76se). A lower but significantly elevatedd-GA excretion was also found in the recovery phase of hepatitis at a time when both serum transaminases and bilirubin were considerably reduced (SGOT 89 I.U.±14se; SGPT 185 I.U.±30se; serum bilirubin 1.05 mg/100 ml±0.20se). Urinary glucuronides and free glucuronic acid, measured as total glucuronic acid, were also significantly increased in early hepatitis (1164 mg/24hr±54se vs 782 mg/24hr±84se in normal subjects), but no correlation was found withd-GA excretion. A short treatment with phenobarbital which led to a 3-fold increase ofd-glucaric acid in 12 normal subjects did not cause any further change in the patients with early acute hepatitis. While the mechanism of the urinaryd-GA increase in hepatitis still remains underfined, the findings of this study support the conclusion that its increase may not reflect an induction of liver microsomal enzymes.     

Aminoguanidine inhibits the development of accelerated diabetic retinopathy in the spontaneous hypertensive rat

Summary Arterial hypertension has been identified as a major secondary risk factor for diabetic retinopathy. However, the mechanisms by which hypertension worsens retinopathy are unknown. Inhibition of advanced glycation product formation prevents the development of experimental diabetic retinopathy in normotensive diabetic rats. In this study the effect of hypertension on the rate of diabetic retinopathy development and the formation of arteriolar thrombosis was evaluated. We also evaluated the effect of aminoguanidine, an inhibitor of advanced glycation end product formation on retinal pathology of diabetic hypertensive rats. After 26 weeks of diabetes, hypertension accelerated the development of retinopathy despite a lower mean blood glucose level than in the non-hypertensive group (diabetic spontaneous hypertensive rats (SHR) 16.00±6.83 mmol/l; diabetic normotensive Wistar Kyoto rats (WKY) 34.9±3.64 mmol/l; p<0.0001). Diabetic SHR had nearly twice as many acellular capillaries as diabetic WKY (SHR diabetic: 91.9±7.5 acellular capillaries per mm² of retinal area vs WKY diabetic: 53.7±8.5 acellular capillaries per mm² of retinal area), and a 3.8-fold increase in the number of arteriolar microthromboses (SHR diabetic 23504±5523 m² vs SHR non-diabetic 6228±2707 m²). Aminoguanidine treatment of SHR diabetic rats reduced the number of acellular capillaries by 50%, and completely prevented both arteriolar deposition of PAS-positive material and abnormal microthrombus formation. These data suggest that hypertension-induced deposition of glycated proteins in the retinal vasculature plays a central role in the acceleration of diabetic retinopathy by hypertension.     

d-Lysine reduces the non-enzymatic glycation of proteins in experimental diabetes mellitus in rats

Summary d-Lysine, the non-physiological isomer of l-lysine, can competitively reduce protein non-enzymatic glycation in vitro. To study the effect of d-lysine in vivo, 6–8-week old Sprague-Dawley rats with streptozotocin-induced diabetes mellitus were treated from diagnosis for 45 days with two daily subcutaneous injections of d-lysine (0.5 g·ml^–1·day^–1). Another group of diabetic rats was only injected with equal volumes of physiological saline (0.9% NaCl). Glycated haemoglobin was measured by ion exchange chromatography, and glycated serum and lens proteins by boronate affinity gel chromatography. Serum and urinary creatinine concentrations were evaluated by the alkaline-picrate reaction. Urinary lysine concentrations at mid- and end-study were evaluated by cation exchange chromatography. Blood glucose concentrations, serum creatinine levels and creatinine clearances, measured at the end of the study, were similar in both diabetic groups (> 22.0 mmol/l, 106 mol/l and 0.02 ml/s, respectively). Urinary lysine concentration in d-lysine-treated diabetic animals was more than 50-fold higher than in placebo-treated diabetic rats. In d-lysine-treated vs placebo-treated diabetic animals, a statistically significant reduction was found in the levels of glycated haemoglobin (stable HbA₁; mean ± SD=3.00±0.74% vs 4.02±0.46%, p<0.05; labile HbA₁=3.92±0.89% vs 5.84±0.61%, p<0.005), glycated serum proteins (1.40±0.47% vs 2.52±1.15%, p<0.05) and glycated lens proteins (4.90±0.96% vs 5.98±0.65 %,p<0.05). Thus, d-lysine (i) is not nephrotoxic and (ii) causes a significant reduction of the early glycation products at the protein level. Therefore, the d-amino acid could be useful in attempting to control damaging phenomena associated with or due to an enhanced protein non-enzymatic glycation.     

Hemodynamic effects of hypothyroidism induced by methimazole in normal and portal hypertensive rats

Portal hypertension is accompanied by a hyperdynamic circulatory state that shares some similarities with thyrotoxicosis. This study was conducted in order to investigate the hemodynamic effects of hypothyroidism in a rat model with portal hypertension induced by partial portal vein ligation (PVL). Four groups of 10 rats each were studied: normal control and hypothyroid rats, and PVL control and hypothyroid rats. Hypothyroidism was induced by methimazole 0.04% in drinking water. Hemodynamic measurements were performed using the radioactive microsphere technique. Induction of hypothyroidism was confirmed by elevated TSH levels. In the PVL groups, hypothyroidism ameliorated the hyperdynamic circulation. Portal venous inflow and portal pressure dropped significantly: 7.1±0.2 vs 4.8±0.3 ml/min/100 g body wt (P<0.01) and 13.4±0.9 vs 10.9±0.8 mm Hg; (P<0.01), respectively. In normal rats, hypothyroidism was manifested by a hypodynamic circulatory state. These results demonstrate that hypothyroidism induced by methimazole is followed by amelioration of the hyperdynamic circulation, normalization of portal venous inflow, and reduction of portal pressure.     

Selenium absorption by canine jejunum

Deficiency of the trace element selenium causes disease in domestic animals and may also be implicated in the pathogenesis of some human itlness. In this study, the triplelumen perfusion method was used to measure the rate of absorption of trace quantities of selenium (50 g/liter in a physiological electrolyte solution) from the jejunum when given asd,l-selenomethione,d,l-selenocystine, or sodium selenite to healthy dogsin vivo. Selenium absorption from the test segment (expressed as percent administered dose per centimeter±sem) was 1.97±0.04 fromd,l-selenomethionine, 1.15±0.06 fromd,l-selenocystine, and 0.51±0.07 from sodium selenite (P<0.01,N=5). In separate studies in four anesthetized dogs, the jejunum was perfused withl-[⁷⁵Se]selenomethionine while concentrations of⁷⁵Se were measured in the portal venous blood; these studies established that [⁷⁵Se]selenomethionine disappearing from the gut lumen corresponded quantitatively to⁷⁵Se appearing in the portal venous effluent (74±6%) and incorporated into intestinal tissue (24±5%). These results are consistent with the hypothesis that the absorption of amino acid-bound selenium is accelerated by the specific amino acid active transport mechanisms in the gut mucosa. Sodium selenite is absorbed more slowly, possibly by simple diffusion through the intestinal mucosa, than the amino acid-bound selenium compounds.Financial assistance was received from the Medical Research Council of New Zealand, the Medical Research Distribution Committee, the Telford Trust and the Medical Research Service of the Veterans Administration.     

Effect of interleukin-11 on ameliorating intestinal damage after methotrexate treatment of breast cancer in rats

Gastrointestinal mucositis after cancer chemotherapy is an increasing problem that is essentially untreatable once established, although it gradually remits. The aim of this study was to investigate the time-course and effect of interleukin-11 (IL-11) on apoptosis and intestinal morphometry as measures of mucositis. Female DA rats were implanted subcutaneously with syngeneic breast cancer and treated with methotrexate (MTX). Intestinal morphometry was used to assess villus area, crypt length, and mitotic count per crypt. Apoptosis was assessed by TUNEL assay in the tumor and jejunum. Tumor proliferation was assessed by mitotic count. The time-course study showed that MTX increased apoptosis by 28-fold in the crypts of the small intestine and by 3-fold in the tumor, and peaked at 6 hr after chemotherapy. IL-11 (100 g/kg/ twice daily subcutaneously) maintained intestinal weight, and reduced the severity of mucositis, as measured by villus area, crypt length, and mitotic count per crypt. IL-11 at higher doses (200 g and 400 g/kg/twice daily subcutaneously), did not further improve villus area, crypt length, and mitotic count per crypt. IL-11 did not affect tumor apoptosis or proliferation. We conclude that IL-11 attenuated mucositis by maintaining intestinal weight and morphometry. IL-11 did not prevent apoptosis, but rather induced compensatory crypt cell proliferation.     

Protective effect of vitamin E supplementation on increased thermal stability of collagen in diabetic rats

Summary Products similar to non-enzymatic glycation end products are known to arise from the interactions between proteins and lipid peroxides in vitro. In this study, we assessed the effect of vitamin E, which possibly modifies lipid peroxide, on advanced glycation end products or similar products in vivo by measuring the fluorescence and thermal rupture time of tail tendon collagen in streptozotocin-induced diabetic rats. The diabetic rats and non-diabetic rats were fed a vitamin E supplemented diet, and a control diet starting 3 days after the streptozotocin injection. After the 4-week treatment, the serum lipid peroxide levels expressed as thiobarbituric acid reactants in the diabetic rats on control diet (15.9 ± 2.6 mol/l [SEM]) were significantly (p <0.05) higher than in the non-diabetic rats (7.9 ± 1.3 mol/l on control diet and 3.3 ± 0.4 mol/l on supplemented diet), but the levels in the diabetic rats on supplemented diet (7.9 + 2.3 mol/l) were reduced to the normal levels. No significant differences were found in serum glucose and glycated haemoglobin levels within the diabetic rats on control and supplemented diets. Both the fluorescence and thermal rupture time of collagen were significantly (p <0.05) increased in the diabetic rats on both diets compared with those in the corresponding non-diabetic rats. Although there was no significant difference in the collagen-linked fluorescence within the diabetic rats on control and supplemented diets, the thermal rupture time was significantly (p <0.01) shortened with supplemented diet (10.8 ± 0.7 min on supplemented diet vs 15.0 ± 0.7 min on control diet). The effect of vitamin E on the thermal rupture time was not observed in non-diabetic rats (6.6 ± 0.5 min on supplemented diet vs 6.2 ± 0.5 min on control diet). These results indicate that the formation of advanced glycation end products or similar products seen in hyperglycaemia can be partially inhibited by vitamin E supplementation by lowering lipid peroxide levels or oxidative stress. This study is thought to be the first to show vitamin E as an anti-oxidant agent limiting the formation of advanced glycation end products or similar products in vivo.     

Hemodynamic studies in long- and short-term portal hypertensive rats: the relation to systemic glucagon levels

It is not known whether the hyperdynamic state which has been observed in several experimental models and in patients with portal hypertension reflects a temporary phase during the evolution of the portal hypertensive syndrome or is an expression of a permanent steady state. A hemodynamic study was performed in a group of rats with long-standing portal hypertension induced by portal vein constriction performed 6.2 +/- 0.1 months earlier. A group of rats matched by age and weight with short-term (20.7 +/- 0.9 days) portal hypertension and a group of long-term (6.2 +/- 0.1 months) sham-operated rats were used as controls. Cardiac output and regional blood flows were measured using a radioactive microsphere technique. Arterial blood levels of glucagon, a known vasodilator that was implicated in the etiology of the hyperdynamic circulation, were also measured. Portal pressure in long- and short-term portal hypertensive groups (12.3 +/- 0.4 and 13.7 +/- 0.4 mm Hg; not statistically significant) was higher than in the sham group (9.0 +/- 0.3 mm Hg; p less than 0.01). Cardiac output in the long-term portal hypertensive rats was similar to the sham-operated group and lower than in the short-term portal hypertensive group (19.4 +/- 1.0 and 20.6 +/- 1.5 vs. 32.7 +/- 2.0 ml X min-1 X 100 gm body weight-1; p less than 0.01). Portal venous inflow in the long-term portal hypertensive group was also similar to the sham group and lower than in the short-term portal hypertensive group (4.51 +/- 0.36 and 4.58 +/- 0.39 vs. 6.72 +/- 0.48 ml X min-1.(ABSTRACT TRUNCATED AT 250 WORDS)     

Renal proteinases and kidney hypertrophy in experimental diabetes

Summary IDDM is associated with an increase in kidney size, which is due to cellular hypertrophy and progressive matrix accumulation within the glomerulus and throughout the tubulointerstitium. The present study addressed the potential role of cysteine and metalloproteinases in renal hypertrophy of short-term diabetes. Three weeks after induction of streptozotocin diabetes in rats, intraglomerular gelatinase activity (streptozotocin: 23±4 vs control: 44±3 mU/g DNA) and cathepsin L + B activity (streptozotocin: 6.7±0.8 vs control: 9.3±0.7 U/g DNA) were significantly decreased. Insulin treatment completely prevented the decline in glomerular proteinase activity (gelatinase: 37±6 mU/g DNA; cathepsin L + B: 9.6±0.9 U/g DNA). In isolated proximal tubules a similar pattern of enzyme activity could be observed. Three weeks of diabetes caused a significant decline in cathepsin L + B activity (streptozotocin: 28±2 vs control: 37±3 U/g DNA). Insulin treatment again prevented the decline in these tubular proteinase activities. In parallel, kidney weight increased by 22% and glomerular protein/DNA ratio rose by 17% in untreated diabetic rats. Diabetic rats receiving insulin displayed a normal glomerular protein/DNA ratio and the kidney weight was increased by only 5%. These results show that renal hypertrophy of early diabetes is closely associated with a decline in both glomerular and tubular proteinase activity. Adequate insulin substitution prevented renal hypertrophy and the reduction in proteinase activity.Abbreviations AMC 7-Amino-4-methyl coumarin - EDTA ethylene diamine tetra-acetic acid - PMSF phenylmethylsulfonyl fluoride - TGF- transforming growth factor- - TIMP tissue inhibitor of metalloproteinases - GFR glomerular filtration rate - IDDM insulin-dependent diabetes mellitus     

Increased Plasma Levels of Corticosterone and Prolactin and Decreased T3 and T4 Levels in Short-Term Prehepatic Portal Hypertension in Rats

Corticosterone, T₃, T₄, and prolactin serum concentrations at 24 hr (N = 10), 15 days (N = 10), and 45 days (N = 10) of postoperative (postop) evolution were assayed to study the neuroendocrine response to portal hypertension. A triple stenosing ligature of the portal vein was used as the surgical technique of portal hypertension. This technique does not produce mortality and causes a decrease in the serum concentrations of T₃ (0.043 ± 0.009 vs 0.55 ± 0.08 ng/ml) and T₄ (3.93 ± 0.55 vs 4.65 ± 0.67 g/ml) and an increase in those of prolactin (28.61 ± 20.20 vs 12.84 ± 3.96 ng/ml) and corticosterone (397.50 ± 64.17 vs 311.53 ± 57.41 ng/ml) at 45 days postop. The T₃, T₄, prolactin, and corticosterone alterations are associated with a persistent increase of TNF- and NO, whose serum concentrations at 45 days postop are, respectively, 1838.33 ± 247.07 vs 48.89 ± 8.75 pg/ml and 0.43 ± 0.13 vs 0.19 ± 0.01 mmol/ml. TNF- and NO could mediate these hormonal alterations in the evolution of short-term portal hypertension in the rat; thus they are involved in the systemic neuroendocrine response that is induced by this injury.