Protective effects of regulatory amino acids on ischemia-reperfusion injury in the isolated perfused rat liver

OBJECTIVE: Some amino acids (AAs) display potent regulatory activities on cell metabolism, including via anti-oxidative defences. The aim of this study was to evaluate the protective effect of these AAs on warm ischaemia-reperfusion (I/R) injury in the isolated perfused rat liver. MATERIAL AND METHODS: Livers from fasted male Sprague-Dawley rats were isolated and perfused without (control group) or with (AP group) a mixture of regulatory AAs (glutamine, histidine, leucine, methionine, proline, phenylalanine, tryptophan and alanine). After 45 min of perfusion, warm ischaemia was induced for 45 min by clamping the portal vein catheter; thereafter, reperfusion was performed for 30 min. RESULTS: TNF-alpha production was significantly lower in the AP group during reperfusion (Control: 39+/-7 versus AP: 16+/-2 pg min-1 g-1, p<0.05), and lactate dehydrogenase (LDH) release decreased significantly during the last 15 min of reperfusion (Control: 0.13+/-0.03 versus AP: 0.04+/-0.02 IU min-1 g-1, p<0.05), despite similar levels of oxidative stress. The addition of regulatory AAs was not associated with variations in portal flow, bile flow, hepatic glucose or urea metabolism. However, significant changes in intrahepatic glutamine (Control: 1.4+/-0.2 versus AP: 2.6+/-0.5 micromol g-1, p < 0.05) together with higher glutamate release in the AP group (Control: 10.2+/-5.4 versus AP: 42.6+/-10.9 nmol min-1 g-1, p < 0.05) indicated modifications in nitrogen metabolism. CONCLUSIONS: Taken together, the lower TNF-alpha production, suggesting decreased inflammatory response, the decrease in LDH release in the AP group, demonstrating a better preservation of liver viability, and the increase in hepatic glutamine indicate that AAs play an important role in the liver's response to I/R.     

Different hemodynamic patterns of alcoholic and viral endstage cirrhosis: Analysis of explanted liver weight,degree of fibrosis and splanchnic Doppler parameters

Objective. In cirrhosis, portal hemodynamics is usually considered independently of the disease etiology. The objective of this study was to investigate the role of the etiology of liver disease on the relationship between liver blood flow and liver pathology in endstage cirrhosis. Material and methods. Portal blood velocity and volume, congestion index of the portal vein, and hepatic and splenic pulsatility indices were evaluated with echo-Doppler in cirrhotic patients immediately before liver transplantation. When a patent paraumbilical vein was present, its blood flow was measured and effective portal liver perfusion was calculated as portal blood flow minus paraumbilical blood flow. The hemodynamic parameters were correlated with liver weight and the pattern of the liver fibrosis morphometrically assessed in explanted livers. A total of 131 patients with alcoholic or viral cirrhosis were included in the study. Results. In alcoholic cirrhosis, liver weight was higher than that in viral disease (1246±295 g versus 1070±254 g, p=0.001), portal liver perfusion per gram of liver tissue was lower (0.49±0.36 ml g^?1 min^?1 versus 0.85±0.56 ml g^?1 min^?1, p=0.004) and hepatic pulsatility indices were higher (1.45±0.31 versus 1.26±0.30, p=0.018). The degree of liver fibrosis was similar in alcoholic and viral cirrhosis (11.7±5.5% versus 11.0±4.4%, p=NS). An inverse relationship between liver weight and Child-Pugh score was disclosed in viral (p<0.001) but not in alcoholic disease. Conclusions. A different hemodynamic pattern characterizes the advanced stage of cirrhosis of alcoholic and viral origin. A more severe alteration of intrahepatic portal perfusion, probably coexisting with a more severe hepatocyte dysfunction, and a higher liver weight can be detected in alcoholic cirrhosis.     

Effects of vascular or luminal administration and of simultaneous glucose availability on glutamine utilization by isolated rat small intestine

This study examined whether the route of glutamine administration and the simultaneous availability of glucose affect intestinal glutamine metabolism. We measured net substrate exchange rates of glutamine and its nitrogenous products in the isolated vascularly and luminally perfused rat small intestine (a) as a function of glutamine provision from either the vascular or the luminal or simultaneously from both sides and (b) as a function of simultaneous availability of glucose from various routes. When glutamine was provided from the lumen, only 19–32% of absorbed glutamine appeared intact in the venous effluent, but the release of metabolic products was 170±5 nmol N min^–1 g^–1. This measure of intestinal glutamine metabolism was unchanged when glutamine was available only in the vascular perfusate (164±6 nmol N min^–1 g^–1). It increased, however, to 271±14 nmol N min^–1 g^–1 (P<0.001) when glutamine was available simultaneously from both the luminal and the vascular perfusate. Glutamine consumption (–110±6 vs. –70±5 or –91±5 vs. –73±7 nmol min^–1 g^–1; P<0.05 each) and the production of citrulline (11.4±0.7 vs. 10.0±0.8 or 9.8±0.5 vs. 7.8±0.4 nmol min^–1 g^–1; P<0.05 each) or ammonia (124±7 vs. 88±4; P<0.01 or 78±4 vs. 68±5 nmol min^–1 g^–1) decreased when glucose (vascular or luminal perfusate) became available in addition to glutamine. We conclude that glutamine is utilized by the small intestine very efficiently regardless of the route of administration being enteral or parenteral. The two routes can be used interchangeably to provide the intestinal mucosa with glutamine. Glucose and glutamine may partially substitute each other, most likely for the purpose as a metabolic fuel. Accepted: 4 March 1999     

A Synthetic Prostaglandin E2 Analogue,Enprostil, Hastens Gastric Emptying of Solids in Patients with an Active Duodenal Ulcer

The effect of gastric emptying of two doses (35 and 70μg) of enprostil given orally was evaluated in eight patients with endoscopically confirmed duodenal ulcer. Gastric emptying of a radiolabelled solid meal was assessed with the use of a gamma camera. Enprostil dose-dependently accelerated gastric emptying of solids; the gastric emptying index, Ix, increased from 1.62 ± 0.38 min^?1· 10^?2 after placebo to 2.77 ± 0.56 min^?1 · 10^?2 after 35 μg enprostil (p < 0.05 versus placebo) and to 3.65 ± 0.64 min^?1 · 10^?2 after 70 μg enprostil (p < 0.005 versus placebo). The fraction of the radiolabelled food retained in the stomach at the end of the gastric emptying examination (that is, after 90 min) amounted to 50.5 ± 6.9% after placebo, 35.2 ± 7.4% after 35 μ enprostil, and 24.1 ± 8.4% after 70 μg enprostil. It is concluded that enprostil elicits a significant speeding up of solid-phase gastric emptying in duodenal ulcer patients.     

The Splanchnic Circulation and Postural Hypotension in Diabetic Autonomic Neuropathy

Postural hypotension results from sympathetic failure to cause superior peripheral vasoconstriction. The importance of the splanchnic circulation was studied by measuring mesenteric artery blood flow with duplex Doppler scanning. Nine normal and 9 Type 1 diabetic controls were compared to 8 Type 1 patients with autonomic neuropathy whose pressure fell 40–113 mmHg (range) on tilting. Measurements were made supine and after vertical tilt, fasting without insulin and after a 550 kcal meal. Superior mesenteric artery diameter decreased on tilting in normal controls but not in diabetic control or neuropathy groups (supine vs tilted: controls. 6.3 ± 0.9 to 5 ± 0.9 mm, p = 0.004, diabetic controls: 6.0 ± 0.6 to 6.0 ± 1.0 mm, and neuropathy group: 6.4 ± 0.9 to 5.6 ± 0.9 mm), but proportional blood flow changes were similar in all subjects (controls: 407 ± 154 to 255 ± 67 ml min^?1 (-31%, p = 0.03), diabetic controls: 379 ± 140 to 306 ± 149 ml min^?1 (-8%, p = 0.28), neuropathy group: 639 ± 371 to 435 ± 142 ml min^?1 (-23%, p = 0.10). Postprandially supine superior mesenteric artery flow increased in all subjects but this did not affect the degree of systolic blood pressure drop on tilting (fasting vs postprandial blood flow: controls: 407 ± 154 to 775 ± 400 ml min^?1 (p = 0.04), diabetic controls: 379 ± 140 to 691 ± 262 ml min^?1 (p = 0.01), neuropathy group: 639 ± 371 to 943 ± 468 ml min^?1 (p < 0.06)). The similarity of superior mesenteric artery responses to tilting in the three groups, and the lack of exacerbation of postural hypotension in the presence of postprandial hyperaemia indicates that control of splanchnic blood flow is less important in the aetiology of diabetic autonomic postural hypotension than previously thought.     

Correlates of reperfusion ventricular fibrillation in dogs

To elucidate determinants of reperfusion ventricular fibrillation (VF), regional myocardial blood flow, ATP, creatine phosphate (CP), heart rate and blood pressure were compared in 2 groups of anesthetized dogs: those that fibrillated spontaneously upon release of a 15-minute coronary artery occlusion (VF group, n = 8) and those that did not fibrillate when reperfused (No VF group, n = 27). Arterial pressure and heart rate before and during coronary artery occlusion were similar in both groups. Ischemie endo- and epicardial ATP values, measured at the end of the occlusion period, were reduced approximately 20% of nonischemic values in both groups. In contrast, CP (nmohmg protein^?1) within the ischemie zone was significantly lower in the VF group in both the epicardium (14.3 ± 1.6 in the VF group vs 22.8 ± 2.5 in the No VF group, p < 0.01) and the endocardium (9.0 ± 2.0 in the VF group vs 18.7 ± 1.8 in the No VF group, p < 0.01). Furthermore, epi- and endocardial regional myocardial blood flow in the center of the ischemic zone during occlusion was significantly lower in VF dogs than in No VF dogs. Epicardial flow was 0.06 ± 0.03 ml·min^?1·g^?1in VFdogsvs 0.44 ± 0.06 in No VF dogs (p < 0.001) and endocardial flow was 0.03 ± 0.02 ml·min^?1·g^?1 in VF dogs vs 0.23 ± 0.04 ·ml-min^?1·g^?1 in No VF dogs (p < 0.001). These data suggest that low levels of regional myocardial blood flow and CP during coronary artery occlusion are associated with an increased risk of VF on reperfusion. Thus, the severity of ischemia in the center of the ischemie zone may be a determinant of reperfusion VF.     

Action Profile of the Rapid Acting Insulin Analogue: Human Insulin B28Asp

The time-action profile of the human insulin analogue B28Asp, which displays faster absorption rates from subcutaneous tissue compared to soluble human insulin, was studied under euglycaemic glucose clamp conditions (blood glucose 5.0 mmol l^?1) in 14 healthy male volunteers. Subcutaneous injection of 0.15 U kg^?1 body weight (range 9.5–14.3 U) of the insulin analogue or soluble human insulin resulted in half-maximal glucose infusion rates (after subtraction of mean baseline glucose infusion rates) that were reached significantly earlier after injection of B28Asp (45 ± 11 (SD) min) as compared to human insulin (58 ± 25 min, p < 0.05). Forty-five and 60 min after injection of human insulin, glucose infusion rates had increased by 3.4 ± 1.8 and 4.8 ± 2.3 mg min^?1 kg^?1 above baseline glucose infusion rates, reflecting 30 ± 15 and 42 ± 17% of maximal action of 10.6 ± 2.7 mg min^?1 kg^?1. Following the injection of B28Asp, glucose infusion rates increased by 6.3 ± 2.7 after 45 min and by 7.9 ± 2.8 mg min^?1 kg^?1 after 60 min above baseline glucose infusion rates, reflecting 64 ± 28% and 81 ± 26% of maximal action of human soluble insulin (p < 0.001). Peak glucose infusion rates after injection of B28Asp were significantly higher and were reached earlier than after subcutaneous injection of soluble human insulin (p < 0.05 and p < 0.001). The human insulin analogue B28Asp showed a significantly faster onset of action as compared to soluble human insulin.     

The Regulation of Post-prandial Cellular Cholesterol Metabolism in Type 2 Diabetic and Non-diabetic Subjects

The purpose of the study was to determine the effect of diabetes on the regulation of postprandial cholesterol metabolism. Four groups of patients (n = 8 for each group) were examined: Type 2 diabetic patients with and without hypercholesterolemia and nondiabetic subjects with and without hypercholesterolaemia. Serum lipoproteins, lipoprotein composition, cellular cholesterol, and cellular cholesterol synthesis were measured before and 4 h after a high calorie meal. The BMI for the hypercholesterolaemic diabetic patients of 31.5 ± 0.95 (SEM) was significantly higher than that for the control group of 26.2 ± 1.0 (p < 0.01). Fasting triglyceride levels were significantly higher in the normocholesterolaemic and hypercholesterolaemic diabetic patients and in the hypercholesterolaemic non-diabetic subjects (1.45 ± 0.22, 2.27 ± 0.34, and 1.58 ± 0.18 mmol l^?1, respectively) compared with normocholesterolaemic non-diabetic subjects (0.75 ± 0.12 mmol l^?1: p < 0.01). The normocholesterolaemic and hypercholesterolaemic diabetic subjects had significantly lower fasting serum high density lipoprotein (HDL) (1.06 ± 0.08 and 1.04 ± 0.06 mmol l^?1) compared to the corresponding non-diabetic groups (1.29 ± 0.11 and 1.45 ± 0.17 mmol l^?1, p < 0.05). The esterified/free cholesterol ratio of very low density lipoprotein (including chylomicrons VLDL-C) decreased postprandially in all groups with an overall decrease of 1.33 to 0.83 (p < 0.01). Fasting cellular cholesterol in mononuclear leucocytes from normocholesterolaemic diabetic patients was similar to that for hypercholesterolaemic diabetic (36.8 ± 1.2 vs 40.6 ± 5.5 mg g^?1 protein) and non-diabetic subjects (36.7 ± 6.8 mg g^?1 protein) and significantly greater than cholesterol in cells from control subjects (29.7 ± 1.5 mg g^?1 protein, p < 0.05). In cells from control subjects only, there was a significant postprandial increase in cholesterol to 39.4 ± 5.2 mg g^?1 protein (p < 0.05) and a corresponding postprandial reduction in cholesterol synthesis from 149 ± 34 to 102 ± 33 nmol g^?1 cell protein (p < 0.05). These results demonstrate a lack of correlation between serum and cellular cholesterol in diabetic patients and an inability to suppress cellular cholesterol synthesis postprandially in these patients. The differences may, in part, explain the increased deposition of cholesterol in atheromatous plaques in normocholesterolaemic diabetic patients.     

Characterization of the Insulin-antagonistic Effect of Growth Hormone in Insulin-dependent Diabetes Mellitus

To characterize its insulin-antagonistic effect, growth hormone (GH) was infused at variable rates (24, 12 or 6 ***mU kg^?1 min^?1) for 1 h in 7 IDDM patients. Saline infusion was used as control (C) and all patients participated in all studies. The effect of insulin was measured with the euglycaemic clamp technique for 6 h combined with d–(3–³H)–glucose to evaluate glucose turnover. The insulin levels during the clamps were similar in all studies (23 ± 3 ***mU I^?1). The infusions produced peak GH levels of (24 rate = 24) 157 ± 11, (12 rate = 12) 76 ± 7, and (6 rate = 6) 45 ± 8 ***mU 1^?1 (mean ± SEM). The insulin-antagonistic effect of GH on glucose uptake was seen after 2 h and was at a maximum 4 to 5 h after the start of the GH infusion (difference in glucose infusion rate between C and 24 was 1.7 ± 0.4 mg kg^?1 min^?1p < 0.01). The resistance was due to a less pronounced effect of insulin to both inhibit rate of appearance and to stimulate rate of disappearance. Infusion of GH at 12 mU kg^?1 min^?1 induced a less pronounced insulin resistance both with regards to maximal effect (glucose infusion rate C - GH 1.4 ± 0.5 mg kg^?1 min^?1p < 0.05) and duration (3 h). At 6 ***mU kg^?1 min^?1a clear GH-induced insulin-antagonistic effect was only seen during the third hour of the clamp (glucose infusion rate C-GH 1.3 ± 0.5 mg kg^?1 min^?1p < 0.05). GH infusion impaired the effect of insulin to lower both the levels of free fatty acids (NEFA) and glycerol between 2 and 5 h after the start of the infusion (NEFA, C:110 ± 29, 24:303 ± 95, p < 0.05: glycerol, C:32 ± 4, 24:50 ± 7 μmol I^?1p < 0.05). The present study therefore demonstrates that the insulin-antagonistic effect of GH in IDDM is related to the plasma levels both with regard to duration and response. The results also indicate that GH impairs the effect of insulin on lipolysis in IDDM after physiological peaks.     

Forearm Substrate Exchange during Hyperinsulinaemic Hypoglycaemia in Normal Man

To assess muscle substrate exchange during hypoglycaemia, 8 healthy young male subjects were studied twice during 2 h of hyperinsulinaemic euglycaemia followed by 4 h of (1) hypoglycaemia (plasma glucose < 2.8 mmol l^?1), and (2) euglycaemia. Insulin was infused at a rate of 1.5 mU kg^?1 min^?1 throughout. When compared to euglycaemia, hypoglycaemia was associated with: (1) increment in circulating glucagon (65 ± 8 vs 23 ± 4 ng l^?1, p < 0.05), growth hormone (19.9 ± 3.6 vs 2.6 ± 1.3 μg l^?1, p < 0.05), adrenaline (410 ± 88 vs 126 ± 32 ng l^?1, p < 0.05) and increased suppression of C-peptide (0.5 ± 0.1 vs 1.0 ± 0.1 μg l^?1, p < 0.05) along with a modest lowering of insulin (103 ± 10 vs 130 ± 13 mU l^?1, p < 0.05); (b) decrease in plasma glucose level (3.0 ± 0.07 vs 5.0 ± 0.12 mmol l^?1 p < 0.05), forearm glucose uptake (0.21 ± 0.09 vs 1.21 ± 0.21 mmol l^?1, p < 0.05) and requirement for exogenous glucose (5.6 ± 1.1 vs 13.2 ± 0.9 mg kg^?1 min^?1 p < 0.005) together with an impaired suppression of isotopically determined endogenous glucose production (0.34 ± 0.5 vs ?2.3 ± 0.3 mg kg^?1 min^?1, p < 0.05); (3) exaggerated increase in blood lactate (1680 ± 171 vs 1315 ± 108 μmol l^?1, p < 0.05) and a decrease in alanine (215 ± 18 vs 262 ± 19 μmol l^?1, p < 0.05). Forearm release of lactate (130 ± 43 vs 12 ± 31 μmol l^?1, p = 0.09) tended to be increased, whereas alanine balance (18 ± 6 vs 17 ± 5 μmol l^?1) was unchanged. (4) Total forearm blood flow increased similarly during both studies (4.4 ± 0.6 vs 4.2 ± 0.5 ml 100 ml^?1 min^?1). These data suggest that the human forearm is not a major site for glucose uptake nor for lactate production during protracted hypoglycaemia; the fact that forearm glucose uptake is reduced sixfold during hypoglycaemia further suggests that restriction of glucose uptake in muscles plays a frontline role in the defence against hypoglycaemia.     

Effect of intraaortic balloon counterpulsation on regional myocardial blood flow and oxygen consumption in the presence of coronary artery stenosis: Observations in an awake animal model

The mechanism by which intraaortic balloon pumping ameliorates myocardial ischemia in patients with unstable angina pectoris is uncertain. Accordingly, the following study was performed to determine the effect of intraaortic balloon pumping on regional myocardial blood flow and myocardial oxygen consumption (MVO₂) distal to severe coronary artery stenosis. Nine closed chest conscious pigs were instrumented with a 7.5 mm long plastic stenosis which reduced vessel diameter by 82%. Measurements of hemodynamics, regional myocardial blood flow (microsphere technique) and MVO₂ were made (1) before intraaortic balloon pumping, (2) at the end of 15 to 20 minutes of intraaortic balloon pumping, and (3) 20 minutes after its discontinuation.Control endocardial blood flow (ml · min^{? 1} · g^{? 1}) distal to the stenosis (1.04 ± 0.20, mean ± 1 standard deviation [SD]) was less than endocardial flow in myocardium perfused by the unobstructed circumflex coronary artery (1.67 ± 0 0.77, p < 0.01). Likewise, control distal zone epicardial flow (1.16 ± 0.36) was reduced in comparison with control circumflex zone epicardial flow (1.48 ± 0.60, p < 0.01In response to intraaortic balloon pumping rate-pressure product declined versus control (10,300 ± 2,090 [SD] mm Hg · min^{? 1} to 9,110 ± 2,010, p < 0.005), whereas aortic mean diastolic pressure (mm Hg) increased versus control (109.0 ± 9.9 to 121.0 ± 13.8, p < 0.01). Distal coronary mean diastolic pressure did not change in response to intraaortic balloon pumping (61.9 ± 13.0 to 68.7 ± 16.5, p = NS). Likewise, endocardial blood flow (ml · min^{? 1} · ^{? 1}) distal to the stenosis did not change during intraaortic balloon pumping (1.00 ± 0.24) versus control (1.04 ± 0.20). In contrast, during intraaortic balloon pumping epicardial blood flow distal to the stenosis declined versus control (1.16 ± 0.36 to 1.01 ± 0.27, p < 0.05). Regional MVO₂ (ml · min^{? 1} · 100 g^{? 1}) distal to the stenosis also decreased versus control in response to intraaortic balloon pumping (12.90 ± 3.55 to 10.30 ± 2.52, p < 0.05). Furthermore, regional MVO₂ correlated well (r = 0.74, p < 0.002) with rate-pressure product.Thus, intraaortic balloon pumping reduces myocardial oxygen demand but does not improve blood flow distal to a severe coronary stenosis; (2) blood flow distal to a severe stenosis may fail to increase with intraaortic balloon pumping because (A) distal coronary mean diastolic pressure may not increase, and (B) blood vessels distal to the stenosis tend to autoregulate in response to a decline in myocardial oxygen demand; and (3) intraaortic balloon pumping ameliorates myocardial ischemia in patients with unstable angina pectoris primarily by reducing oxygen demand rather than by increasing oxygen supply.     

Short Administration of Metformin Improves Insulin Sensitivity in Android Obese Subjects with Impaired Glucose Tolerance

In a double-blind, randomized, cross-over study, the metabolic effects of a short treatment with metformin (2 times 850 mg day^?1 for 2 days and 850 mg 1 h before evaluation) were compared to those of placebo in 15 obese subjects (BMI: 33.2 ± 0.9 kg m^?2), with abdominal distribution of adipose tissue and impaired glucose tolerance. An intravenous glucose tolerance test (0.3 g glucose kg^?1) was performed after each period of treatment. Areas under the curve (AUC_{0–180 min}) were calculated for plasma glucose, insulin, and C-peptide levels. Glucose tolerance was estimated by the coefficient of glucose assimilation (K_G). Insulin sensitivity (S_I) and glucose effectiveness (S_G) indices were calculated using Bergman's minimal model. Insulin secretion rate (ISR) was determined by deconvolution of plasma C-peptide levels and insulin metabolic clearance rate (MCR) was estimated by dividing AUC ISR by AUC insulin. Fasting plasma insulin levels were reduced after metformin (89.3 ± 15.9 vs 112.4 ± 24.3 pmol I^?1; p = 0.04). AUC glucose, K_G and S_G were similar in both tests. However, AUC insulin was reduced (39.7 ± 6.5 vs 51.8 ± 10.4 nmol min I^?1; p = 0.02), while S_I (6.98 ± 1.14 vs 4.61 ± 0.42 10^?5 min^?1 pmol^?1 I; p = 0.03) and insulin MCR (715 ± 116 vs 617 ± 94 ml min^?1 m^?2; p = 0.03) were increased after metformin. The demonstration that metformin rapidly improves insulin sensitivity should encourage further research to evaluate the long-term effects of metformin in android obese subjects with impaired oral glucose tolerance.     

Effect of apoE/ATP‐containing liposomes on hepatic energy state

Background/Aims: ATP‐containing liposomes partially prevent ATP depletion in the cold‐stored liver. As hepatocytes can specifically bind apoE, we investigated whether the addition of apoE to large (200 nm) ATP‐containing liposomes increases their uptake by the liver and further improves hepatic energy stores. Methods: Livers from fasted male Hartley guinea‐pigs (231±3 g) were perfused for 90 min under our standard conditions (Control, n=6) or after a single bolus addition of plain liposomes (Lip, n=6), ATP (5 μmol)‐containing liposomes (ATP‐Lip, n=6) or apoE/ATP‐containing liposomes (0.8 or 8 mg apoE/g phospholipids; apoE1‐Lip and apoE10‐Lip, respectively, n=6 in each group). Liposome uptake and its impact on energy and nitrogen metabolism were studied. Results: At its highest concentration, apoE significantly increased liposome uptake (apoE10‐Lip:?9.17±0.69 vs apoE1‐Lip:?6.18±0.44 vs ATP‐Lip:?6.40±0.88 nmol min^?1 g^?1; P<0.05). This was associated with a significant increase in intrahepatic ATP (apoE10‐Lip: 1033±137 vs apoE1‐Lip: 811±98 and ATP‐Lip: 648±36 nmol g^?1; P<0.05), which was restored to its level in non‐perfused livers. Hepatic viability and nitrogen metabolism were not affected. Conclusions: Hepatic ATP content being a key factor in the maintenance of liver graft function, apoE/ATP‐containing liposomes should be useful in liver preservation for transplantation.     

The influence of hypoglycaemia on regional cerebral blood flow and cerebral volume in Type 1 (insulin-dependent) diabetes mellitus

Summary The effect of moderate hypoglycaemia (venous blood glucose 2.0±0.2 mmol/l;mean±SD) on regional cerebral blood flow and cerebral volume was studied in a group of ten right-handed patients with Type 1 (insulin-dependent) diabetes mellitus (age 26.0±2.4 years, duration 18.4±3.8 years) using an intravenous Xenon 133 single photon emission computed tomography technique. After 10 min of hypoglycaemia, global cerebral blood flow had increased to 55.8±4.5 ml·100g⁻¹·min⁻¹ compared to the initial normoglycaemic flow of 49.5±3.7 ml·100 g⁻¹·min⁻¹ (p<0.01). A further increase in global cerebral blood flow to 59.5±4.5 ml·100 g⁻¹·min⁻¹ (p<0.05) occurred 15 min after normalization of the blood glucose level. The global cerebral blood flow change from before hypoglycaemia to after recovery was inversely related to the initial glucose level. No change in the relative distribution of the regional cerebral blood flow was found between the measurements. The cerebral blood flow was significantly higher in the right hemisphere compared with the left hemisphere (2.3, 1.6 and 2.2%, respectively;p<0.05) in all measurements. Deeper hypoglycaemia was associated with a more pronounced decrease in brain volume, while the length of the restitution time after hypoglycaemia correlated with a volume increase. Due to influences with opposite effects there was no mean change in the brain volume.     

Renal functions in obstructive sleep apnea patients

Purpose

The aim of this study is to investigate possible factors influencing glomerular filtration rate (GFR) in obstructive sleep apnea (OSA).

Methods

Data of OSA patients admitted to Gaziantep University sleep clinic from January 2005 to January 2010 were retrospectively evaluated. GFR is calculated with the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation. Patients younger than 18 years old were excluded.

Results

The mean age of OSA (n?=?634) and control group (n?=?62) were 51.13?±?11.61 and 50.69?±?13.88 years, respectively (p?=?0.81). The mean estimated GFR (eGFR) was 90.73?±?19.59 ml/min/1.73 m² in OSA patients and 94.14?±?18.81 ml/min/1.73 m² in control subjects (p?=?0.19). GFR was 84.25?±?20.87 ml/min/1.73 m² in patients with left ventricular hypertrophy (LVH) while it was 93.94?±?18.44 ml/min/1.73 m² in patients without LVH (p?=?0.00). GFR of male subjects was 92.1?±?19.23 in OSA and 95.84?±?20.08 ml/min/1.73 m² in controls (p?=?0.33). GFR of female and male patients in the OSA were 87.45?±?20.10 and 92.91?±?18.02 ml/min/1.73 m², respectively (p?=?0.13). Serum creatinine was higher in OSA patients compared to controls (p?=?0.01). GFR was 92.30?±?19.27 in male and 88.33?±?19.84 ml/min/1.73 m² in female subjects (p?=?0.01). GFR was 84.86?±?19.95 in hypertensive patients while it was 95.11?±?18.20 ml/min/1.73 m² in normotensive subjects (p?=?0.00). GFR was 89.30?±?19.96 in patients with metabolic syndrome (MetS) and it was 93.46?±?18.68 ml/min/1.73 m² in patients without MetS (p?=?0.00).

Conclusions

GFR values were lower in sleep apneic patients with MetS as well as in patients with hypertension and LVH.

     

Inhibition of glucose production and stimulation of bile flow by R (+)‐α‐lipoic acid enantiomer in rat liver

Abstract: Aims/Background: R (+)‐α‐lipoic acid (RLA) has been suggested for the treatment of liver diseases, but has also been shown to improve glucose utilization in diabetic patients. Because detailed information of RLA action on carbohydrate metabolism in intact liver is lacking, we examined concentration‐dependent effects of RLA on hepatic glucose production. Methods: RLA (10^?6?10^?3 mol L^?1) or buffer (control) was infused in isolated livers of fasted rats during recirculating perfusion for 90 min (n = 4–6/group). Hepatic glucose and lactate fluxes and bile secretion were continuously monitored. Results: RLA reduced lactate (10 mmol L^?1)‐dependent glucose production in concentration‐dependent fashion (R = ? 0.780, P < 0.001) by up to 67% compared with control (0.36 ± 0.02 µmol min^?1 g^?1). In parallel, RLA dose dependently decreased lactate uptake (R = ? 0.592, P < 0.001) also by up to 67% (control: 0.58 ± 0.08 µmol min^?1 g^?1). RLA (10^?4 mol L^?1 and 10^?3 mol L^?1) stimulated bile flow by ～ 20 and ～ 50%, respectively (P < 0.02 vs. control). After 10^?3 mol L^?1 RLA infusion, liver glycogen was ～ 3 fold higher (5.2 ± 1.1 vs. control: 1.8 ± 0.2 µmol g^?1, P < 0.002). Also at low lactate concentrations (1 mmol L^?1), 10^?3 mol L^?1 RLA reduced glucose production by ～ 53% and lactate uptake by ～ 60%, but stimulated bile secretion by ～ 50% (P < 0.05). Conclusion: RLA reduces hepatic glucose release by inhibiting lactate‐dependent glucose production in a concentration‐dependent fashion.     

Symptoms,Hormones, and Glucose Fluxes During a Gradual Hypoglycaemia Induced by Intraperitoneal vs Venous Insulin Infusion in Type I Diabetes

Intraperitoneal (IP) insulin infusion with programmable implantable pumps is associated with a reduction in hypoglycaemic events when compared to intensive diabetes management with subcutaneous insulin in patients with Type 1 diabetes mellitus. The mechanism may involve more physiological insulin kinetics, lower peripheral insulin levels or a specific hepatic action of portal insulin on hypoglycaemic counter regulation. To investigate the latter two hypotheses, we performed two hypoglycaemic clamps (controlled blood glucose decrement to 2.2 mmol l^?1) in random order in 12 Type 1 diabetic patients. Insulin was infused either IP or IV for 150 min, at rates chosen to generate similar peripheral insulin levels (1 mU/kg^?1 min^?1 IV or 2 mU/kg^?1 min^?1 IP, n = 6) to evaluate direct hepatic action, or at similar rates (1 mU/kg^?1 min^?1 IV and IP, n = 6) to evaluate IP indirect effects via lower peripheral insulinaemia. Hepatic glucose production and glucose utilization were measured by [6, 6 ²H] glucose dilution technique. Glucose production was lower (1.7 ± 0.4 vs 0.5 ± 0.4 mg kg^?1min^?1, p < 0.05), and utilization was similar at the end of the matched-insulinaemia IV and IP clamps, respectively. By contrast, glucose production was higher (1.7 ± 0.5 IV vs 2.7 ± 0.3 IP mg kg^?1 min^?1, p < 0.01) and glucose utilization lower (4.4 ± 1.0 IV vs 3.3 ± 0.2 IP mg kg^?1 min^?1, p < 0.05) with IP delivery at the end of the matched-dose clamps. Counterregulatory hormones and hypoglycaemic symptoms increased similarly in all clamps. In summary, IP insulin, when compared to IV insulin at similar delivery rates, but not at similar insulinaemia, is associated with a less negative glucose balance (glucose production-glucose utilization) during hypoglycaemia. Such a mechanism may play a role in the reduced hypoglycaemic risk seen with IP implantable pumps.     

Endogenous nitric oxide modulates small intestinal nutrient transit and activity in healthy adult humans

Objective. Nitric oxide (NO) mechanisms have been shown to modulate fasting small intestinal motility in humans, but a role in the regulation of human postprandial small intestinal motility has not been assessed. The aim of this study was to evaluate the effect of the NO synthase inhibitor NG-monomethyl-l-arginine (l-NMMA) on the regulation of small intestinal nutrient transit and postprandial small intestinal motility in healthy humans. Material and methods. Seven healthy male volunteers (18–27 years) underwent antroduodenal manometry recordings for 4 h on 2 occasions after intraduodenal instillation of a 500 KJ [120 Kcal] test meal. The meal was administered 15 min after the commencement of a 60-min intravenous infusion of l-NMMA (4 mg kg^?1 h^?1) or saline (0.9%). Studies were separated, performed in randomized order and >3 days apart. The frequency and amplitude of duodenal pressure waves together with time to return of fasting motility (phase III) was determined. On each day, small intestinal transit was measured using a lactulose breath test. Results. The test meal interrupted fasting small intestinal motility in all subjects. The time to recurrence of fasting motility following its postprandial disruption was similar (l-NMMA versus saline 1.6±0.2 h versus 1.9±0.1 h; p>0.05). Duodenocaecal transit was delayed by infusion of l-NMMA compared with saline (l-NMMA versus saline 92.1±3.9 min versus 66.4±6.4 min; p<0.005). Infusion of l-NMMA significantly increased the frequency (l-NMMA versus saline 50.4±6.6 versus 34.8±5.5 waves per 30 min; p<0.05) and amplitude (l-NMMA versus saline 20.4±1.5 versus 15.5±1.1 mmHg; p<0.01) of duodenal pressure waves. Conclusions. These data suggest that endogenous NO may play a role in the regulation of small intestinal nutrient transit by regulating small intestinal motility in healthy individuals.     

Preservation of Renal Haemodynamic Response to an Oral Protein Load in Non-insulin-dependent Diabetes Mellitus

Glomerular Filtration Rate (GFR) and Effective Renal Plasma Flow (ERPF) were determined, for 2h prior to and 3h following the ingestion of a 1.2 g kg^?1 meat meal, in seven normotensive normoalbuminuric Type 2 diabetic patients exhibiting good glycaemic control (fasting plasma glucose (mean ± SD): 7.2 ± 2.0 mmol l^?1; glycosylated haemoglobin: 8.1 ± 1.7%) and in nine normal subjects selected for similar basal GFR values. Baseline GFR and ERPF (corrected to 1.73 m² surface area) were 83 ± 10 and 410 ± 76 ml min^?1 for the Type 2 diabetic patients and 86 ± 11 and 405 ± 113 ml min^?1 for the normals. GFR increased by 38 ± 8 and 32 ± 15% in the diabetic patients and normals, to 108 ± 25 and 105 ± 26 ml min^?1 (p < 0.01 vs baseline). Peak ERPF was 501 ± 127 and 476 ± 119 ml min^?1 for the two respective groups (p < 0.01 vs baseline). Filtration fractions at peak GFR and EPRF values were unchanged from baseline for either groups. Fractional clearance of albumin for the Type 2 diabetic patients was unaltered by protein ingestion. Therefore, protein ingestion in Type 2 diabetes, as in normals, results in an acute elevation of GFR. Absolute and incremental changes in GFR were identical for the two groups. These data demonstrate a preserved capacity for renal vasodilatation in Type 2 diabetic patients despite their greater chronological age.     

The Role of Plasma Non-esterified Fatty Acids During Exercise in Type 2 Diabetes Mellitus

Elevated fasting plasma non-esterified fatty acid (NEFA) levels have been reported in Type 2 diabetes. We examined whether such changes persist during low-grade exercise and influence carbohydrate metabolism. Eight Type 2 diabetic patients with moderate glycaemic control and eight healthy controls received the anti-lipolytic agent, acipimox, or placebo on separate occasions before exercising for 45 min at 35 % pre-determined V_o2max. Fasting plasma NEFA levels were similar (0.40 ± 0.06 (SEM) and 0.45 ± 0.05 mmol l^?1; healthy and Type 2 diabetic subjects) following placebo, and increased to comparable levels with exercise (0.73 ± 0.07 and 0.73 ± 0.10 mmol l^?1). Acipimox lowered basal NEFA levels (0.14 ± 0.03 and 0.28 ± 0.04 mmol I^?1; both p < 0.05 vs placebo), and prevented the rise with exercise. Blood glucose (p < 0.001) and serum insulin (p < 0.01) levels were higher in the Type 2 diabetic patients (vs controls) for both treatments. Whole body lipid oxidation increased from baseline to a comparable degree with exercise following placebo (3.2 ± 0.3 and 2.8 ± 0.3 mg kg^?1 min^?1; healthy and Type 2 diabetic subjects, both p < 0.02). Although less marked, the same was also observed following acipimox (2.0 ± 0.4 and 2.1 ± 0.5 mg kg^?1 min^?1; both p < 0.05). Carbohydrate oxidation increased with exercise in both subject groups, but with no significant difference between the treatments. Thus, the metabolic response to low-grade exercise was normal in Type 2 diabetic patients with moderate glycaemic control, but occurred against a background of hyperinsulinaemia. Plasma NEFA do not exert a major regulatory effect on carbohydrate metabolism during low-grade exercise.