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Context: Sugar alcohols (also called polyols) are regarded as a "healthy" sugar substitute. One of the possible reasons for their safe use in pregnant women is their natural origin and the presence of polyols in maternal and fetal samples during normal human gestation. But little is known about the association between circulating sugar alcohols levels and maternal metabolic disorders during pregnancy., Objective: We aimed to detect the concentration of the polyols in participants with and without gestational diabetes mellitus (GDM), and to investigate the association between maternal serum levels of polyols and GDM, as well as newborn outcomes., Methods: A nested population-based case-control study was conducted in 109 women with and without GDM. Maternal concentrations of serum erythritol, sorbitol, and xylitol in the fasting state were quantified using a time of flight mass spectrometry system., Result: In women with GDM, serum concentrations of erythritol and sorbitol were higher, but serum concentrations of xylitol were lower than those in women without GDM. Per 1-SD increment of Box-Cox-transformed concentrations of erythritol and sorbitol were associated with the increased odds of GDM by 43% and 155% (95% CI 1.07-1.92 and 95% CI 1.77-3.69), while decreased odds were found for xylitol by 25% (95% CI 0.57-1.00). Additionally, per 1-SD increase of Box-Cox-transformed concentrations of serum sorbitol was associated with a 52% increased odds of large for gestational age newborns controlling for possible confounders (95% CI 1.00-2.30)., Conclusion: Maternal circulating sugar alcohols levels during pregnancy were significantly associated with GDM. These findings provide the potential roles of polyols on maternal metabolic health during pregnancy., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Endocrine Society.)

Background and Aims: Alcohol-associated liver disease (ALD) is a common chronic liver disease worldwide with high morbidity and mortality, and no Food and Drug Administration-approved therapies. Fructose (dietary or endogenous), its metabolite uric acid, and aldose reductase (AR, the only endogenous enzyme that produces fructose) are strongly associated with the development of nonalcoholic fatty liver disease. However, the role of AR or its metabolites in ALD remains understudied and was examined using human specimens, cultured cells, and mouse model systems., Approach and Results: We demonstrated in liver specimens from patients with alcoholic hepatitis, the AR up-regulation and elevated AR metabolites (sorbitol, fructose, and uric acid), which correlated significantly with (1) increased lipid peroxidation byproducts and endoplasmic reticulum (ER) stress, (2) decreased protective ER chaperones, and (3) greater cell death and liver injury. Furthermore, we established a causal role for AR in ALD by showing that the genetic deficiency of AR (knockout mice) prevented alcohol-induced increase in harmful AR metabolites, toxic aldehydes, steatosis, ER stress, apoptosis, and liver injury. Finally, we demonstrated the therapeutic potential of pharmacological AR inhibition against alcohol-induced hepatic injury in experimental ALD., Conclusions: Our data demonstrate that hepatic AR up-regulation, and consequent elevation in fructose, sorbitol and/or uric acid, are important factors contributing to alcohol-induced steatosis, ER stress, apoptosis, and liver injury in both experimental and human ALD. Our study provides a strong rationale to evaluate AR as a potential therapeutic target and to test AR inhibitors to ameliorate alcohol-induced liver injury., (© 2020 by the American Association for the Study of Liver Diseases.)

Interorgan immunological communication is critical to connect the local-systemic innate immune response and orchestrate a homeostatic host defense. However, the factors and their roles in this process remain unclear. We find Drosophila IMD response in guts can sequentially trigger a systemic IMD reaction in the fat body. Sugar alcohols of the polyol pathway are essential for the spatiotemporal regulation of gut-fat body immunological communication (GFIC). IMD activation in guts causes elevated levels of sorbitol and galactitol in hemolymph. Aldose reductase (AR) in hemocytes, the rate-limiting enzyme of the polyol pathway, is necessary and sufficient for the increase of plasma sugar alcohols. Sorbitol relays GFIC by subsequent activation of Metalloprotease 2, which cleaves PGRP-LC to activate IMD response in fat bodies. Thus, this work unveils how GFIC relies on the intermediate activation of the polyol pathway in hemolymph and demonstrates that AR provides a critical metabolic checkpoint in the global inflammatory response., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Epalrestat is an inhibitor of aldose reductase in the polyol pathway and is used for the management of diabetic neuropathy clinically. Our pilot experiments and accumulated evidences showed that epalrestat inhibited polyol pathway and reduced sorbitol production, and suggested the potential renal protection effects of epalrestat on diabetic nephropathy (DN). To evaluate the protective effect of epalrestat, the db/db mice were used and exposed to epalrestat for 8 weeks, both the physiopathological condition and function of kidney were examined. For the first time, we showed that epalrestat markedly reduced albuminuria and alleviated the podocyte foot process fusion and interstitial fibrosis of db/db mice. Metabolomics was employed, and metabolites in the plasma, renal cortex, and urine were profiled using a gas chromatography-mass spectrometry (GC/MS)-based metabolomic platform. We observed an elevation of sorbitol and fructose, and a decrease of myo-inositol in the renal cortex of db/db mice. Epalrestat reversed the renal accumulation of the polyol pathway metabolites of sorbitol and fructose, and increased myo-inositol level. Moreover, the upregulation of aldose reductase, fibronectin, collagen III, and TGF-β1 in renal cortex of db/db mice was downregulated by epalrestat. The data suggested that epalrestat has protective effects on DN, and the inhibition of aldose reductase and the modulation of polyol pathway in nephritic cells be a potentially therapeutic strategy for DN.

Herbal medicines have become a core interest, and they are used widely. Lagenaria siceraria is known for its antihyperglycemic, antidyslipidemic, antioxidant potential, and the present study was designed to explore the possible role of L. siceraria in attenuation of diabetic complications via in vitro modulation of advanced glycation end products (AGEs), sorbitol, and aldose reductase (ALR)-three major biomarkers of diabetic complications. To the best of our knowledge, no study has yet been carried out to explore L. siceraria to inhibit these biomarkers. Hydroalcohol extract of L. siceraria (LHA) was evaluated for its ability to scavenge 2,2-diphenyl-1-picrylhydrazyl (DPPH), hydrogen peroxide, nitric oxide, and superoxide radicals, total antioxidant capacity, and reducing-power assay. Antiglycation activity was carried out by bovine serum albumin (BSA) fluorescence method. Sorbitol accumulation was evaluated in red blood cells (RBCs) and ALR1 was obtained from kidney of rat to carry out the study. Quercetin was also quantified by high-performance liquid chromatography (HPLC) analysis with 14.3 mg per 100 g of LHA. LHA exhibited 854 mg/g gallic acid equivalent of phenol content and 104 mg/g quercetin equivalent of flavonoids and was found to be significantly active against the antioxidant assays evaluated. LHA has shown 80.12% inhibition of AGE formation. LHA was found to be effective against sorbitol accumulation and ALR1 inhibition with IC 50 198.25 μg/ml and 6.24 μg/ml, respectively. These results reveal that LHA may exert beneficial effects against diabetic complications by its antioxidant and antiglycation potential.

Luseogliflozin is a selective sodium glucose co-transporter 2 (SGLT2) inhibitor that reduces hyperglycemia in type 2 diabetes mellitus (T2DM) by promoting urinary glucose excretion (UGE). A clinical pharmacology study conducted in Japanese patients with T2DM confirmed dose-dependency of UGE with once-daily administration of luseogliflozin; however, the reason for sustained UGE after plasma luseogliflozin decreased was unclear. To elucidate the effect of inhibition rate constants, K on and K off , and to explain the sustained UGE, a pharmacokinetic-pharmacodynamic (PK-PD) model was built based on the mechanisms of glucose filtration in the glomerulus and reabsorption in the renal proximal tubule of kidney as well as the kinetics of competitive inhibition of SGLT1/2 and inhibition rate constants of SGLT2, by using UGE and plasma glucose levels and luseogliflozin concentrations. This acquired population PK-PD model adequately described the sustained UGE and the estimated population means of the inhibition constant for SGLT2 (K i2 ) and inhibition-rate constants for SGLT2 (K on and K off ) were 0.31- and 3.6-fold lower or higher than the in vitro values. Because the dissociation half-time of luseogliflozin from SGLT2 calculated from K off , 6.81 h, was consistent with the value in vitro, we considered that the sustained UGE could be explained by the long dissociation half-time. Moreover, by calculating the SGLT2 inhibition ratio using the model, we discuss other properties of the UGE time course after luseogliflozin administration.

Aim: Luseogliflozin is a novel sodium-dependent glucose cotransporter-2 inhibitor for the treatment of Type 2 diabetes mellitus. To assist pharmacokinetic and toxicodynamic studies, a rapid LC-MS/MS method were developed and validated for the quantitation of luseogliflozin in rat plasma., Results: Sample preparation was carried out using simplified protein precipitation and liquid-liquid extraction procedures, and the run time was only 4 min. Extraction recovery was 92.9 to 95.3%, and the method was validated over the range 0.5 to 500 ng/ml for luseogliflozin with acceptable specificity, accuracy and precision., Conclusion: The validated method is considered suitable to quantify luseogliflozin in pharmacokinetic and pharmacodynamic/toxicodynamic studies in rats.

Objectives: We evaluated the effects of S-allylcysteine (SAC) on biomarkers of the polyol pathway in streptozotocin-nicotinamide (STZ-NA)-induced diabetes in rats., Methods: Diabetes was induced in male albino Wistar rats by intraperitoneal administration of STZ (55 mg kg -1 bw -1 ) and NA (110 mg kg -1 bw -1 ). SAC (150 mg kg -1 bw -1 ) was orally administered to the rats with diabetes for 45 days to assess its effects on blood glucose, insulin, insulin resistance, glycated hemoglobin, aldose reductase (AR), sorbitol dehydrogenase (SDH), sorbitol, fructose, thiobarbituric acid-reactive substances (TBARS), hydroperoxide, hemoglobin and glutathione (GSH)., Results: On SAC administration in the rats with diabetes, the levels of blood glucose, insulin resistance, glycated hemoglobin, AR, SDH, sorbitol, fructose, TBARS and hydroperoxide increased significantly (p<0.05), whereas those of insulin, hemoglobin and GSH decreased. SAC showed therapeutic effects similar to those of gliclazide in decreasing blood glucose, AR, SDH, sorbitol, fructose, glycosylated hemoglobin, TBARS and hydroperoxides levels and significant increases in insulin, hemoglobin and GSH activity in rats with diabetes. Moreover, histopathologic studies also revealed the protective effect of SAC on pancreatic beta cells., Conclusions: The results indicate that SAC prevents complications of diabetes by reducing the influx of glucose in the polyol pathway, thereby elevating the GSH level and reducing the activities of AR and SDH. Therefore, SAC may have imperative implications for the deterrence and early treatment of type 2 diabetes., (Copyright © 2016 Canadian Diabetes Association. Published by Elsevier Inc. All rights reserved.)

Background: Lipid emulsion infusion reverses cardiac toxicity of local anesthetics. The predominant effect is likely creation of a "lipid sink." This in vitro study determined the extent to which Intralipid® (Fresenius Kabi, Uppsala, Sweden) and Lipofundin® (B. Braun Melsungen AG, Melsungen, Germany) sequester anesthetics from serum, and whether it varies with pH., Methods: Bupivacaine, ropivacaine, and mepivacaine were added to human drug-free serum (pH 7.4) at 10 μg/ml. The lipid emulsions were added, and the mixture shaken and incubated at 37°C. Lipid was removed by ultracentrifugation and drug remaining in the serum measured. Additional experiments were performed using 100 μg/ml bupivacaine and at pH 6.9., Results: Lipofundin® extracted all three anesthetics to a greater extent than Intralipid® (34.7% vs..22.3% for bupivacaine, 25.8% vs..16.5% for ropivacaine, and 7.3% vs..4.7% for mepivacaine). By increasing either concentration of bupivacaine or lipid, there was an increase in drug extraction from serum. Adjusting the pH to 6.9 had no statistically significant effect on the percentage of bupivacaine sequestered., Conclusions: Bupivacaine, ropivacaine, and mepivacaine were sequestered to an extent consistent with their octanol:water partition constants (logP). In contrast with previous studies of extraction of lipids from buffer solutions, an emulsion containing 50% each of medium- and long-chain triglycerides extracted local anesthetics to a greater extent from human serum than one containing exclusively long-chain triglycerides, calling into question recent advanced cardiac life support guidelines for resuscitation from anesthetic toxicity that specify use of a long-chain triglyceride. The current data also do not support recent recommendations to delay administration until pH is normalized.

Novel carboxymethylated pyridoindoles, characterized by antioxidant activity combined with the ability to inhibit aldose reductase, represent an example of a multitarget approach to the treatment of diabetic complications - severe diabetes-related health disorders of multifunctional nature. One of the novel carboxymethylated pyridoindoles, (2-benzyl-2,3,4,5-tetrahydro-1H-pyrido[4,3-b]indol-8-yl)-acetic acid (compound 1), was found to inhibit aldose reductase with the IC(50) value 18.2 ± 1.2 μM. Owing to aldose reductase pharmacophore requirements for an acidic proton, most aldose reductase inhibitors contain an acetic acid moiety, ionized at physiological pH, resulting in poor bioavailability of the drugs. The presence of a basicity center at the tertiary nitrogen of the carboxymethylated pyridoindoles, in addition to the acidic carboxylic function, predisposes these compounds to form double-charged zwitterionic species. The zwitterionic nature of compound 1 may remarkably affect its pH-lipophilicity profile allowing for increased membrane penetration in the pH region around its isoelectric point, which lies close to the physiological pH 7.4. In the first part of this study, the presence of zwitterionic species was experimentally proved by the concentration-dependent effect of sodium 1-hexanesulphonate on the distribution profile of compound 1. Then a series of experiments was performed in the cellular system of isolated erythrocytes in vitro. Isolated rat erythrocytes exposed to peroxyl radicals, generated in the solution by decomposition of the hydrophilic azoinitiator AAPH or intracellularly by decay of lipophilic t-BuOOH, underwent progressive hemolysis. The onset of the hemolysis was shifted from the starting zero point by the time interval assigned as a lag period. In the presence of compound 1 the lag period was significantly prolonged. Finally, under conditions of a short-term experiment in STZ-diabetic rats in vivo, increase in sorbitol levels in erythrocytes was recorded. Compound 1 administered in the dose 50mg/kg/day (i.g.) significantly decreased the sorbitol level in the erythrocytes. To conclude, the physico-chemical proof of the zwitterionic nature of compound 1 was established and the results obtained in isolated red blood cells indicated good cellular availability of the compound. In addition, in diabetic rats, sorbitol accumulation in red blood cells was significantly inhibited by compound 1 administered intra-gastrically, suggesting its ready uptake into the central compartment. The zwitterionic principle thus may have significant consequences for increased bioavailability of drugs bearing an acidic function., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Aim: Diabetes mellitus (DM) is a risk factor for hepatocellular carcinoma (HCC). It directs glucose to sorbitol and fructose in polyol pathway (PP). To pursue contribution of PP in hepatocarcinogenesis., Methods: We utilized ascorbic acid (AA) and diallyl sulfide (DAS) in experimental DM and HCC against control. HCC was induced by diethyl nitrosamine (DENA, one intraperitoneal (IP) dose 125 mg/kg), DM, by streptozotocin (STZ, IP dose 65 mg/kg). AA was given as 7.4 g/kg/d, I.P., DAS 200mg/kg/d, orally. All animals were killed after 10 weeks., Results: DENA elevated serum AFP, erythrocyte sorbitol (ES), neoplastic changes in liver, lowered blood glucose, increased hepatocyte aldose reductase (AR) and sorbitol dehydrogenase (SDH), significantly alleviated by DAS/AA combination. DM elevated ES activating AR, inhibiting SDH, improved by DAS and AA., Conclusion: Co-induction of DM and HCC increased liver tissue lesion, serum AFP, ES, liver AR and SDH. Co-administration of DAS/AA reduced ES, AR without changing SDH. DAS/AA co-therapy lowered ES by depressing AR without affecting SDH, meaning that AR is activated by cancer and DM in different ways. PP is early marker for HCC detection and response to chemoprevention. DAS/AA combination is promising cost effective chemopreventive and anti-diabetic combination., (Crown Copyright © 2011. Published by Elsevier Ireland Ltd. All rights reserved.)

In an ovine model of placental insufficiency-induced intrauterine growth retardation (PI-IUGR), characterized by hypoxia, hypoglycemia and a significant reduction in fetal weight, we assessed alterations in fetal and placental polyols. Arterial maternal-fetal concentration differences of glucose and mannose were greater in the PI-IUGR fetus; glucose: C (n = 7), 2.68 +/- 0.14 mmol/L versus PI-IUGR (n = 9), 3.18 +/- 0.16 mmol/L (P < 0.02) and mannose: C, 42.9 +/- 8.1 micromol/L versus PI-IUGR, 68.5 +/- 19.1 micromol/L (P < 0.001). For PI-IUGR fetuses, fetal arterial plasma myo-inositol concentrations were significantly increased (P < 0.001). The concentrations of sorbitol, glucose and fructose were significantly reduced (P < 0.03, 0.01, 0.02, respectively). The cotyledons of IUGR placentas had a significantly increased concentration of myo-inositol (P < 0.003) and decreased concentrations of sorbitol, fructose and glycerol (P < 0.01, 0.02, 0.01, respectively). Fetal hepatic concentrations of sorbitol (P < 0.001) and fructose (P < 0.03) were also significantly reduced. These profound changes in both placental and fetal concentrations of polyols and sugars in sheep PI-IUGR pregnancies support the conclusion that within the PI-IUGR placenta there is an increased flux through the glucose 6-P:inositol 1-P cyclase system and decreased flux through the polyol dehydrogenase system, leading to increased placental myo-inositol production and decreased sorbitol production. The decreased placental supply of sorbitol to the fetal liver may lead to decreased fetal hepatic fructose production. These observations highlight that, in association with hypoxic and hypoglycemic PI-IUGR fetuses, there are major placental and fetal alterations in polyol production. The manner in which these alterations in fetoplacental carbohydrate metabolism contribute to the pathophysiology of PI-IUGR is currently unknown.

Diabetic nephropathy is one of the most severe diabetic microangiopathies and accounting for approximately one-third of all cases of end-stage renal disease. In the present study, we investigated the effect of mangiferin, a polyphenol from Anemarrhena asphodeloides Bge. or Mangifera indica L., on diabetic nephropathy and the possible mechanisms by using a developed diabetic nephropathy rat model and cultured rat mesangial cells. Serum-advanced glycation end-products level, malonaldehyde level, sorbitol concentration of red blood cell, 24 h albuminuria excretion were significantly decreased, whereas activity of serum superoxide dismutase and glutathione peroxidase and creatinine clearance rate were increased by mangiferin. Blood glucose level remained unaffected. Mangiferin significantly inhibited glomerular extracellular matrix expansion and accumulation and transforming growth factor-beta 1 overexpression in glomeruli of diabetic nephropathy rats. Moreover, mangiferin was observed to inhibit proliferation of mesangial cells induced by high glucose and the overexpression of collagen type IV of mesangial cells induced by advanced glycation end products. In summary, mangiferin could significantly prevent progression of diabetic nephropathy and improve renal function., ((c) 2009 John Wiley & Sons, Ltd.)

Increased glucose flux through the polyol pathway and the resultant oxidative stress is thought to be a major mechanistic contributor to microvascular diabetic complications. Inhibition of flux through this pathway can be blocked through inhibition of either of 2 enzymes, aldose reductase (AR) or sorbitol dehydrogenase (SDH). This report describes the pharmacokinetics, biomarker pharmacodynamics, and safety of CP-642,931, a potent and specific sorbitol dehydrogenase inhibitor (SDI). CP-642,931 was administered for 7 days to 57 healthy volunteers in doses ranging from 1 to 35 mg daily. After the 35-mg dose, CP-642,931 showed a t((1/2)) of 20.1 hours and t(max) at 0.5 to 1.25 hours. After a 35-mg dose, maximum inhibition of SDH was 91% (on days 1 and 7), and maximum serum sorbitol increase was 152-fold on day 7 compared to control. Five participants discontinued the study due to adverse events, including myalgia, muscle spasm, and muscle fatigue. All symptoms resolved in all but 1 participant, who continued to report intermittent muscle fasciculations upon follow-up. In conclusion, CP-642,931 is a potent and specific SDI that is rapidly absorbed through the oral route and effectively inhibits SDH. However, the drug is not well tolerated due to adverse neuromuscular effects.

Plasma clearance of D-sorbitol, a nontoxic polyol, occurs predominantly in the liver and has been used to measure functional liver blood flow after bolus and steady- state intravenous administration. However, it is not known which of these two administration methods is superior. Therefore, plasma D-sorbitol clearance was studied in an animal model both after a bolus dose and under steady-state (SS) conditions and compared directly with liver blood flow, under normal conditions, and after the induction of endotoxin (LPS) sepsis. Adult male Wistar rats (526 +/- 38 g body wt; n = 27) were anesthetized and mechanically ventilated. Hemodynamics, hepatic arterial flow, and portal venous flow were measured. Two groups were studied, namely healthy animals that served as controls and a sepsis group that received 5 mg/kg LPS intravenously (Escherichia coli O127:B8). Each animal received either a SS infusion (0.1 mg/100 g body wt per min) or a bolus (3 mg/100 g body wt) of a 5% D-sorbitol solution intravenously in a randomized order. After the initial measurements and a 60-min pause time in between (T(1/2,sorbitol) = 9 min), a crossover was done. The hepatic clearance of D-sorbitol in the control group showed a good correlation between bolus and SS (Spearman's r = 0.7681, P = 0.0004), and both techniques correlated well with total liver blood flow (TLBF) (r = 0.7239, P = 0.0023 and r = 0.7226, P = 0.0023, respectively). Also in the sepsis group there was a good correlation between bolus and SS sorbitol clearance (r = 0.6655, P = 0.0182). In the sepsis group, only the SS clearance correlated with TLBF (r = 0.6434, P = 0.024). In conclusion, in normal and under septic conditions, hepatic clearance of D-sorbitol either by bolus or a SS infusion is comparable. In healthy animals, this also correlated well with TLBF but not in septic conditions. However, this is expected because of the changes in the liver microcirculation, shunting, and decreased hepatocyte function in sepsis.

Objectives: Both diabetes mellitus and magnetic resonance image (MRI) deep white matter hyperintensities (WMHs) are more common in bipolar disorder (BD) patients than in matched controls. Deep-as opposed to periventricular--WMHs and diabetes are associated with treatment resistance and poorer outcome. This study investigated whether brain glucose metabolism by the polyol pathway--a pathway linked to nervous tissue disease in diabetes--is related to deep WMH volume and treatment resistance in BD patients., Methods: Volumes of fluid-attenuated inversion recovery WMHs were quantified and correlated with cerebrospinal fluid (CSF) concentrations of glucose metabolites in 20 nondiabetic patients with BD and nondiabetic comparison subjects with schizophrenia (n = 15) or transient neurologic symptoms (neurologic controls, n = 15)., Results: BD patients, but not schizophrenic patients, had significantly greater volumes of deep but not periventricular WMHs compared to neurologic controls. BD subjects also had significantly greater CSF concentrations of sorbitol and fructose (the polyol pathway metabolites of glucose) compared to controls. Significant positive correlations between CSF metabolites and WMH volumes were found only in the BD group and were between deep WMH volumes and CSF sorbitol (rho = 0.487, p = 0.029) and fructose (rho = 0.474, p = 0.035). An index of treatment resistance correlated significantly with deep WMH volume (rho = 0.578, p = 0.008), sorbitol (rho = 0.542, p = 0.013), and fructose (rho = 0.692, p = 0.001) in BD subjects but not in other subjects., Conclusions: This is the first reported evidence of relationships between abnormal brain glucose metabolism and both deep WMHs and treatment resistance in a group of BD patients. Further studies are necessary to determine the significance of these findings to BD pathophysiology.

In order to investigate the underlying mechanism of alterations in bone mineral metabolism in patients with type 2 diabetes, we determined circulating levels of bone functional markers along with urinary excretion of sorbitol (SOR) and bone mineral density (BMD), and also examined their mutual interrelationship. A total of 151 male type 2 diabetic patients were examined in this study. Forty-eight age-matched male healthy subjects were also studied as the controls. A significant reduction of serum intact osteocalcin (i-OC) was found in the diabetic groups (p<0.01). On the other hand, circulating levels of tartrate resistant acid phosphatase (TRAP) in the diabetic patients were significantly higher than those in the controls (p<0.01). Interestingly, a significantly negative relationship was observed between BMD and serum TRAP (p<0.01), although no significant relationship was noted between BMD and serum i-OC in diabetic patients. Urinary excretion of SOR was significantly elevated in the diabetic patients when compared with the controls (p<0.01). In addition, a significantly positive correlation was observed between serum TRAP and urinary SOR (p<0.01), but not between serum i-OC and urinary SOR. Elevated serum TRAP in diabetes was reduced after the administration of aldose reductase inhibitor (p<0.05). It seems most likely that the increase in osteoclastic function probably due to accelerated polyol pathway plays a crucial role in the pathogenesis of decreased bone mineral content in male patients with type 2 diabetes.

Matricaria chamomilla L., known as "chamomile", has been used as an herbal tea or supplementary food all over the world. We investigated the effects of chamomile hot water extract and its major components on the prevention of hyperglycemia and the protection or improvement of diabetic complications in diabetes mellitus. Hot water extract, esculetin (3) and quercetin (7) have been found to show moderate inhibition of sucrase with IC50 values of 0.9 mg/mL and 72 and 71 microM, respectively. In a sucrose-loading test, the administration of esculetin (50 mg/kg body weight) fully suppressed hyperglycemia after 15 and 30 min, but the extract (500 mg/kg body weight) and quercetin (50 mg/kg body weight) were less effective. On the other hand, a long-term feed test (21 days) using a streptozotocin-induced rat diabetes model revealed that the same doses of extract and quercetin showed significant suppression of blood glucose levels. It was also found that these samples increased the liver glycogen levels. Moreover, chamomile extract showed potent inhibition against aldose reductase (ALR2), with an IC50 value of 16.9 microg/mL, and its components, umbelliferone (1), esculetin (3), luteolin (6), and quercetin (7), could significantly inhibit the accumulation of sorbitol in human erythrocytes. These results clearly suggested that daily consumption of chamomile tea with meals could contribute to the prevention of the progress of hyperglycemia and diabetic complications.

Background and Purpose: Hyperglycaemia induces overproduction of mitochondrial reactive oxygen species (ROS) in endothelial cells, which is believed to be a major molecular mechanism underlying complications of diabetes, including diabetic nephropathy. Impairment of endothelium-dependent vasodilatation is found in type 2 diabetes. Urocortin is a 40 amino-acid peptide related to the corticotrophin-releasing factor (CRF) family, which suppresses production of ROS in endothelial cells and sustains endothelium-dependent relaxations of rat coronary artery. However, it is not clear if urocortin has any effect on diabetic nephropathy., Experimental Approach: Possible mechanisms underlying the effects of urocortin on diabetic nephropathy were investigated in db/db mice and cultured rat mesangial cells., Key Results: Urocortin decreased body weight, plasma levels of advanced glycation end-products, blood urea nitrogen and creatinine levels. However, food intake, plasma insulin and glucose levels remained unaffected. Superoxide dismutase activity was increased markedly, whereas malonaldehyde levels in kidney homogenate and sorbitol concentrations in red blood cells were decreased significantly in urocortin-treated mice. Urocortin significantly decreased glomerular extracellular matrix expansion and accumulation in kidney. Moreover, urocortin inhibited the overexpression of transforming growth factor-beta 1 and connective tissue growth factor in rat mesangial cells induced by 25 mM glucose. All the effects of urocortin, except sorbitol accumulation, were abolished by the non-selective CRF receptor blocker, astressin., Conclusion and Implications: Urocortin could significantly ameliorate diabetic nephropathy and this effect was mediated via the CRF receptor.

Canine diabetes mellitus (DM) is a common metabolic disorder with long term complications, most of which are caused by glycosylation of structural proteins, decreases in antioxidant concentrations, altered osmotic balance and hypoxia due to impaired oxygen transport. Previous studies have demonstrated that under hyperglycemic conditions canine erythrocytes undergo swelling, probably due to activation of the polyol pathway. The present work aimed to assess the plasma concentration of advanced glycation end (AGE) products, stable Amadori-products generated by non-enzymatic glycosylation of proteins and the intracellular concentration of sorbitol, produced by the activation of polyol pathway in 34 blood samples from diabetic dogs and in 14 controls. AGE products were significantly higher (p<0.01) in plasma from diabetic dogs compared with control animals. The sorbitol concentration in erythrocytes was also significantly higher in diabetic dogs and, in particular, in poorly compensated animals and in dogs with ketonuria. In five cases that were analysed before and after clinical improvement, sorbitol concentration was found to correlate with improvement. These results suggest that non-specific glycosylation is increased and that the polyol pathway is activated in diabetic dogs in a manner that is proportionate to the severity of disease. Moreover, the concentration of AGE products and sorbitol may be useful for monitoring the onset of diabetic complications and assessing the most appropriate therapeutic approaches for management of canine DM.

Purpose: Activation of polyol pathway due to increased aldose reductase (ALR2) activity has been implicated in the development of diabetic complications including diabetic retinopathy (DR), a leading cause of blindness. However, the relationship between hyperglycemia-induced activation of polyol pathway in retina and DR is still uncertain. We investigated the relationship between ALR2 levels and human DR by measuring ALR2 activity and its product, sorbitol, in erythrocytes., Methods: We enrolled 362 type 2 diabetic subjects (T2D) with and without DR and 66 normal subjects in this clinical case-control study. Clinical evaluation of DR in T2D patients was done by fundus examination. ALR2 activity and sorbitol levels along with glucose and glycosylated hemoglobin (HbA1C) levels in erythrocytes were determined., Results: T2D patients with DR showed significantly higher specific activity of ALR2 as compared to T2D patients without DR. Elevated levels of sorbitol in T2D patients with DR, as compared to T2D patients without DR, corroborated the increased ALR2 activity in erythrocytes of DR patients. However, the increased ALR2 activity was not significantly associated with diabetes duration, age, and HbA1C in both the DR group and total T2D subjects., Conclusions: Levels of ALR2 activity as well as sorbitol in erythrocytes may have value as a quantitative trait to be included among other markers to establish a risk profile for development of DR.

The triggers and pathogenesis of peripheral diabetic neuropathy are poorly understood, and this study evaluated the role of insulinopenia in nociceptive abnormalities in the streptozotocin (STZ) rat model of diabetes to test the hypothesis that, in addition to hyperglycemia, impairment of insulin signaling may be involved in progression of neuropathy. We measured blood glucose, plasma insulin, and sciatic nerve glucose and sorbitol levels, and withdrawal thresholds for hind limb pressure pain and heat pain in STZ-injected rats that developed hyperglycemia or remained normoglycemic. The pressure pain threshold did not change in vehicle-injected controls, but during the 2 weeks after STZ, it decreased by 25-40% in STZ-hyperglycemic and STZ-normoglycemic animals (P<0.05). Mean heat pain threshold did not change in STZ-normoglycemic rats, but increased by about 1.5 degrees C in STZ-hyperglycemic rats (P<0.05). These pain thresholds did not correlate with blood or nerve glucose or sorbitol levels, but both correlated with plasma insulin level in STZ-normoglycemic rats, and low-dose insulin replacement normalized the pressure threshold without affecting blood glucose level. Thus, at least one of early signs of diabetic neuropathy in STZ-treated rats, mechanical hyperalgesia, can be triggered by moderate insulinopenia, irrespective of glycemic status of the animals.

A new, simple and sensitive pre-column high-performance chromatographic method for the determination of diabetes marker d-glucose, 1,5-anhydro-d-glucitol and related compounds is reported. Sugars (d-glucose, d-galactose, d-mannose, sucrose and arabinose) were derivatized with benzoic acid (BA) at 80 degrees C for 60 min. l-Fucose, fructose, d-lactose, l-rhamnose, arabinose and ascorbic acid were not reacted. Sugar alcohols (xylitol, erythritol, mannitol, sorbitol myo-inositol) were also derivatized with BA at 80 degrees C for 60 min. The fluorescence derivatives were separated on a TSK amide 80 column (4.6 mm i.d. x 250 mm, 5 microm) with acetonitrile-50 mm acetate buffer (pH 5.6; 4:96, v/v) as the mobile phase. The detection wavelength of beizoic acid derivatives was lambda(ex) 275 nm and lambda(em) 315 nm. The detection limits of sugars were 10-80 microg/mL. The calibration graphs were linear up to 10 mg/mL. The relative standard deviations of 500 microg/mL sugars were 7.0-7.3%. The proposed method was compared with the enzymatic photometric glucose analysis method (Glucose B-Test II Wako). The correlation coefficient was 0.83 (n = 20) and y = 0.82x + 5.91, where y and x are concentrations in microg/mL obtained by the proposed pre-column HPLC and enzyme-photometric method, respectively. The detection limits of sugar alcohols were 100-1000 ng/mL. The calibration graphs were linear to 50 microg/mL and relative standard deviations of 10 microg/mL were 7.2-8.2%. The 1,5-AG data by the proposed method was also compared with the enzymatic photometric 1,5-AG analysis method (Rana AG 1,5-AG determination kit, Nihon Kayaku) and good correlation (r = 0.91, n = 20) was also obtained. The proposed method was applied to the simultaneous determination of d-glucose, 1,5-AG and related sugar alcohols in serum from healthy males.

We assessed the immediate effect of intravenous immunoglobulins (IVIG) on the biochemical, immunological and hematological profiles in patients with hypogammaglobulinemia. Over a period of three months, patients with antibody deficiencies, who had been established on stable IVIG treatment as replacement therapy in our hospital, were enrolled in the study. Participants underwent pre-therapy determinations of their biochemical, immunological and hematological profiles. Laboratory determinations were repeated after completion of IVIG infusions. Over the study period, fourteen patients were enrolled and a total of 34 pre- and post-IVIG infusion determinations were performed and results compared. We found that low-dose IVIG treatment in patients with hypogammaglobulinemia results in post-infusion biochemical and hematological changes, as follows: an increase in total protein concentration and a reduction in albumin, total cholesterol, sodium and alkaline phosphatase concentrations as well as lymphocyte and platelet counts. All these biochemical and cellular changes seems to be transient, since they were not observed in the subsequent pre-infusion determination. However, in other patient populations, some of these changes might differ, depending on the dose of IVIG administered and the baseline condition and immunological status of the patient.

Evaluation of different extraction methods for quantification of endogenous sorbitol and fructose in human red blood cells (RBCs) and matrix effects in ESI and APCI showed that protein-precipitation followed by mixed-mode solid-phase extraction was more effective extraction method and APCI more effective ionization method. Then the LC/APCI-MS/MS method was fully validated and successfully applied to analysis of clinical RBC samples. The concentrations of endogenous sorbitol and fructose were determined using calibration curves employing sorbitiol-13C6 and fructose-13C6 as surrogate analytes. The method has provided excellent intra- and inter-assay precision and accuracy with a linear range of 50.0-10,000 ng/mL (correlation coefficient >0.999) for sorbitol-13C6 and 250-50000 ng/mL (correlation coefficient >0.999) for fructose-13C6 in human RBCs.

The accumulation of sorbitol by the activated polyol pathway is considered to be a major cause of diabetic neuropathy. Because the erythrocytic sorbitol contents reportedly reflects that in nerves, erythrocytic sorbitol measurement would be useful for confirming the effect of an aldose reductase inhibitor (ARI). In this study, we examined erythrocytic sorbitol contents in healthy subjects and diabetic patients under fasting and postprandial conditions. Then, the contributions of blood aldose reductase (AR) contents and plasma glucose levels to the accumulated erythrocytic sorbitol contents were also analyzed. Erythrocytic sorbitol contents in the healthy subjects were 11.7 and 12.5-12.6 nmol/g Hb in fasting and postprandial status, respectively. In contrast, the erythrocytic sorbitol contents in diabetic patients were apparently higher (approximately 2.5-fold), but fidarestat treatment restored the elevated erythrocytic sorbitol contents to normal. In the diabetic patients, erythrocytic sorbitol contents were highly correlated with blood AR contents multiplied by the plasma glucose levels, whereas in the normal and fidarestat-treated diabetic patients no such correlation was observed. Taken together, these results suggest both the blood AR contents and the plasma glucose levels are factors determining erythrocytic sorbitol contents in diabetic patients. Notably, the potent ARI fidarestat was shown to normalize elevated erythrocytic sorbitol contents.

To investigate the effects of Hachimi-jio-gan on diabetic nephropathy, we employed an animal model, rats subjected to sub-total nephrectomy followed by streptozotocin injection, and administered Hachimi-jio-gan orally at a dose of 50, 100 or 200 mg/kg body weight/day for 15 weeks. The administration of Hachimi-jio-gan reduced dose-dependently the elevated blood glucose and urinary protein excretion levels in rats with diabetic nephropathy over the experimental period, whereas it increased creatinine clearance significantly, suggesting that Hachimi-jio-gan would prevent or delay the progression of diabetic nephropathy. In addition, the serum glycosylated protein and urea nitrogen levels were markedly elevated in rats with diabetic nephropathy compared with normal rats, and were significantly reduced by the administration of Hachimi-jio-gan, whereas Hachimi-jio-gan reversed the decrease in the serum albumin level. The serum triglyceride and total cholesterol concentrations were reduced by Hachimi-jio-gan, implying that Hachimi-jio-gan would improve the metabolic disorder of lipids caused by diabetic nephropathy. Moreover, Hachimi-jio-gan inhibited lipid peroxidation in the serum and kidney, which suggests that Hachimi-jio-gan would ameliorate oxidative stress associated with diabetic nephropathy. Furthermore, the disorders of the glucose-dependent metabolic pathway due to this pathological condition were also normalized by the administration of Hachimi-jio-gan through decreases in advanced glycation end-product formation and sorbitol levels in the kidney. Hachimi-jio-gan protected against the development of renal lesions, glomerular sclerosis, tubulointerstitial lesions, mesangial matrix expansion and arteriolar sclerosis, estimated by histopathological evaluation and scoring. This study suggests that Hachimi-jio-gan may be a novel therapeutic approach to improving diabetic nephropathy., (Copyright 2004 S. Karger AG, Basel)

The amounts of sorbitol (SOR) excreted in 24-h urine were determined on two groups, i.e., diabetic and nondiabetic patients, using an improved method in which ion exchange resin column processing was applied, and these levels were compared with SOR levels in whole blood. Urinary SOR concentration was also determined in diabetic and normal rats in the same manner and its relationship to aldose reductase (AR) activity in whole blood was investigated. Changes in SOR levels in urine and whole blood were compared in diabetic rats after administration of an AR inhibitor (ARI). Whole blood SOR levels and urinary SOR excretion were significantly higher in diabetic patients than in nondiabetic patients. The same results were obtained in the animal models. In diabetic rats, the urinary SOR excretion was about five times higher than that in control rats, and the AR activity in whole blood was also significantly higher. The increase in urinary SOR excretion and whole blood SOR levels, as well as AR activity, in blood in the diabetic state was inhibited by ARI administration. The influence of the diabetic state and the efficacy of the ARI were more marked in urinary SOR excretion than in whole blood SOR levels. These data indicate that determinations of urinary SOR excretion and AR activity are easily measurable and of benefit to assessing the diabetic condition.

We report here on the discovery path that led to a structurally unprecedented non-hydantoin, non-carboxylic acid aldose reductase inhibitor, 24, which shows remarkably potent oral activity in normalizing elevated sorbitol levels and, more significantly, fructose levels in the sciatic nerve of chronically diabetic rats, with ED(90) values of 0.8 and 3 mpk, respectively. It is well absorbed in rats (oral bioavailability, 98%) and has a long plasma t(1/2) (26 +/- 3 h).

Background: We recently demonstrated that aldose reductase inhibition was effective in restoring the reduced migratory capacity of leukocytes in diabetic rats. To investigate the mechanism(s) involved in the restoring effect, we used minalrestat, an aldose reductase inhibitor., Methods: In sodium pentobarbital-anesthetized (40 mg/kg, intraperitoneally) alloxan-diabetic or galactosemic male Wistar rats, the internal spermatic fascia was exteriorized, and the number of leukocytes rolling along the venular endothelium and the number of leukocytes sticking to the vascular wall after topical application of zymosan-activated plasma or leukotriene B(4) (1 ng/ml), as well as after the application of a local irritant stimulus (carrageenan, 100 microg), were determined using intravital microscopy. Data from animals that were treated with and those that were not treated with minalrestat (10 mg/kg/d by gavage) were compared., Results: The reduced number of leukocytes rolling along the venular endothelium (by about 70%) and the number of adhered and migrated leukocytes in postcapillary venules (by 60%) were significantly restored to control values after minalrestat treatment. Total or differential leukocyte counts, venular blood flow velocity or wall shear rate were not altered by minalrestat treatment. The expression of ICAM-1 and P-selectin, cell adhesion molecules involved in the interaction of leukocyte-endothelium, reduced in diabetic rats was restored by minalrestat treatment., Conclusion: We conclude that an enhanced flux through the polyol pathway might be involved in the reduced expression of ICAM-1 and P-selectin contributing to the impaired leukocyte-endothelial interactions in diabetes mellitus and that aldose reductase inhibition restores the defect, restoring the reduced expression., (Copyright 2003 John Wiley & Sons, Ltd.)

Background and Objectives: Atomoxetine is a treatment for attention-deficit/hyperactivity disorder and is primarily eliminated via cytochrome P4502D6 (CYP2D6). The pharmacokinetics of atomoxetine and its primary metabolites were investigated in 10 adults with hepatic impairment (6 moderate, 4 severe) and 10 age- and sex-matched control subjects, all being genotyped as CYP2D6 extensive metabolizers., Methods: A single oral 20-mg dose of atomoxetine was given. Multiple blood samples were collected for 48 hours in healthy subjects and for 120 hours in patients. Urine was collected up to 24 hours. Before atomoxetine administration (10-20 days), sorbitol clearance and debrisoquin (INN, debrisoquine) metabolic ratio were determined as markers of hepatic blood flow and CYP2D6 activity, respectively., Results: The systemic clearance of atomoxetine was significantly reduced in those with hepatic impairment compared with controls, thereby resulting in increased exposure (area under the concentration-time curve from time 0 to infinity, 1.58 versus 0.85 microg. h(-1). mL(-1); P =.035) but no change in maximum concentration. Mean 4-hydroxyatomoxetine area under the concentration-time curve from time 0 to time t and maximum concentration were increased approximately 7-fold and 2-fold, respectively (P =.0001 and P =.0056, respectively). For the glucuronide conjugate of 4-hydroxyatomoxetine, the mean half-life was longer and the mean area under the concentration-time curve from time 0 to infinity and the maximum concentration were lower (P =.0028, P =.003, and P =.0001, respectively). The sorbitol clearance was lower and the debrisoquin metabolic ratio was higher, reflecting reduced hepatic blood flow and decreased CYP2D6 activity, respectively. Decreased atomoxetine clearance in patients with hepatic impairment was clearly correlated with decreased CYP2D6 activity and decreased hepatic blood flow. Mean atomoxetine plasma protein binding was lower in patients with hepatic impairment compared with controls (96.5% versus 98.7%, P =.0008). Atomoxetine was well tolerated in the 2 populations., Conclusion: For patients with attention-deficit/hyperactivity disorder who have hepatic impairment, dosage adjustment is recommended. Initial target doses should be reduced to 25% and 50% of the normal dose for patients with severe and moderate hepatic impairment, respectively.

The phenomena of ionization suppression in electrospray ionization (ESI) and enhancement in atmospheric pressure chemical ionization (APCI) were investigated in selected-ion monitoring and selected-reaction monitoring modes for nine drugs and their corresponding stable-isotope-labeled internal standards (IS). The results showed that all investigated target drugs and their co-eluting isotope-labeled IS suppress each other's ionization responses in ESI. The factors affecting the extent of suppression in ESI were investigated, including structures and concentrations of drugs, matrix effects, and flow rate. In contrast to the ESI results, APCI caused seven of the nine investigated target drugs and their co-eluting isotope-labeled IS to enhance each other's ionization responses. The mutual ionization suppression or enhancement between drugs and their isotope-labeled IS could possibly influence assay sensitivity, reproducibility, accuracy and linearity in quantitative liquid chromatography/mass spectrometry (LC/MS) and liquid chromatography/tandem mass spectrometry (LC/MS/MS). However, calibration curves were linear if an appropriate IS concentration was selected for a desired calibration range to keep the response factors constant., (Copyright 2003 John Wiley & Sons, Ltd.)

Sorbitol accumulation in nerves has been regarded as one of the major causes of diabetic neuropathy. In this study, fidarestat (SNK-860; 1 mg daily), a potent new aldose reductase inhibitor (ARI), or the commercially available ARI epalrestat (150 mg daily), was administered for 4 weeks to 58 Type 2 diabetic patients. Treatment with these drugs had no effect on glycemic control, judging from plasma glucose and HbA(1c) levels. However, fidarestat treatment normalized the elevated sorbitol content of erythrocytes under fasting as well as postprandial conditions. In contrast, the effect of epalrestat was minimal. There were no major side effects with fidarestat. Thus, fidarestat is considered to be a potent and promising ARI, possibly useful for both preventing and treating diabetic neuropathy. Further studies are needed to clarify how much the occurrence and progression of diabetic neuropathy are inhibited by normalizing sorbitol elevation with fidarestat treatment.

Objective: To describe a modified and improved technique which, in one measurement, estimates the influx of irrigation fluid during endoscopic endometrial ablation or prostate resection, and provides both rapid confirmation of the diagnosis and an estimate of the amount of fluid absorbed by detecting markers which pass from the irrigation fluid to the serum, i.e. mannitol or sorbitol., Patients and Methods: Control samples were taken for analysis before irrigation, and test samples were taken on four occasions during and after intervention, from each of 10 patients undergoing transurethral resection of the prostate. Irrigation fluid was also marked with ethanol (1.5% w/v) and the concentration of this agent measured in the blood and expired air of these patients. The absorbed volume was calculated according to the extracellular distribution space of mannitol., Results: Mannitol and sorbitol could be measured in 85% and 73% of the 40 test samples, respectively. The threshold for full sensitivity for breath ethanol concentration to detect absorption was 132 mL., Conclusion: This method for detecting serum mannitol and sorbitol represents a valid procedure for confirming and quantifying the absorption of irrigation fluid in the clinic, which agrees closely with the already established ethanol monitoring procedure and which should now be considered as a reference procedure.

We developed an improved enzymatic assay of D-sorbitol in human erythrocytes by employing highly specific D-sorbitol dehydrogenase from Pseudomonas sp. (EC 1.1.1.14) and replacing perchloric acid (HClO4) and potassium carbonate (K2CO3), generally used for deproteinization, with sodium hydroxide (NaOH) and zinc sulphate (ZnSO4). In this assay, erythrocytes were separated from plasma by centrifugation and washed once with physiological saline. Subsequently, the erythrocytes were lysed with distilled water and proteins precipitated with NaOH and ZnSO4. After centrifugation, the resulting colourless supernatant was mixed with a glycine buffer (pH 9.0) containing NAD+ and D-sorbitol dehydrogenase. After incubation for 30 min at 37 degrees C, the NADH produced was measured fluorimetrically. The fluorescence intensities were corrected for sample blanks, and the values of D-sorbitol were normalized for haemoglobin content. The method had an analytical range of 1-180 micromol/L. The intra- and inter-assay precisions were < 3.3% and < 5.8%, respectively. The detection limit was 0.65 micromol/L. In terms of the linearity, precision and sensitivity, the improved method using NaOH and ZnSO4 was superior to the conventional method using HClO4 and K2CO3.

Introduction: Decreased myo-inositol levels and increased activity of the polyol pathway have been proposed to play a role in causing diabetic microvascular complications. There are few clinical methods for examining the activity of the polyol pathway in diabetic patients. We assessed the effect of changes in glycemic control on polyol pathway activity by measuring urinary polyol excretion., Materials and Methods: Gas-chromatography/mass-spectrometry (GC/MS) was used to assess the urinary excretion of glucose and polyols (myo-inositol, sorbitol, and fructose) in 50 patients who had type 2 diabetes without nephropathy and 20 healthy subjects., Results: In the diabetic patients with poor glycemic control, urinary sorbitol levels were significantly increased and urinary myo-inositol excretion was approximately 6.5-fold higher than in healthy controls (33.0+/-6.5 vs 221.7+/-45.9 mg/day, mean+/-SE, P<0.01). During strict glycemic control, some patients (Group A) showed simultaneous disappearance of glucosuria and normalization of the urinary excretion of myo-inositol (<50 mg/day) and, while others (Group B) showed delayed normalization of urinary myo-inositol excretion. Group B showed significantly higher urinary myo-inositol, sorbitol, and fructose excretion than Group A at the time of disappearance of glucosuria. These findings suggest that patients in Group B may have increased polyol pathway activity., Conclusion: Even though short-term strict glycemic regulations were established in long-standing hyperglycemic diabetic patients, to normalize the once-exaggerated polyol pathway activities, it was essential to maintain glucosuria-free conditions for some period. Quantitation of urinary polyols using GC/MS appears to be a clinically useful method for assessing polyol pathway activity.

Objective: Sorbitol has been suggested as a suitable marker to assess liver blood flow (LBF), after it was shown to adequately reflect prolonged changes in LBF but changes of a shorter duration have not been investigated. We therefore used sorbitol to evaluate drug-induced decreases in LBF of variable duration with i.v. infusions of somatostatin and its synthetic analogue octreotide., Methods: In a double-blind, placebo controlled, randomised study, six healthy males received sorbitol for 170 min. At sorbitol steady state, which was at 45 min after the start of the infusion (t=0), somatostatin or octreotide was infused for 30 min. Sampling for sorbitol assay and echo-Doppler hepatic portal vein flow measurements were done regularly and treatments were compared using ANOVA., Results: The sorbitol AUC over the 30-min intervention period was 15% (95% C.I.: +4, +22%) and 13% (+5, +24%) higher compared to placebo after somatostatin and octreotide respectively. The decline of sorbitol levels after termination of the intervention was faster for somatostatin compared to octreotide, demonstrated by the difference in the AUC (0-2 h) with placebo which was 8% (-3, +19%) lower after somatostatin, and 15% (+5, +26%) after octreotide. Portal venous blood flow decreased during the 30-min interventions; after somatostatin 27% (-14, -40%) and after octreotide 29% (-17, -42%). Portal flow was lower than placebo during the entire experiment after octreotide 30% (-10, -50%), but not after somatostatin 13% (-33, +7%). Changes in sorbitol levels and portal venous blood flow occurred simultaneously and were well correlated for each individual, making it likely that the interventions did not interfere with metabolism., Conclusion: Sorbitol can be used to adequately assess decreases in LBF of variable duration in healthy volunteers.

Objectives: Recombinant tissue factor pathway inhibitor (rTFPI) has been shown to be an effective treatment in animal models of sepsis and is under investigation for human use. Reduced liver blood flow during septic shock may substantially alter the pharmacokinetics of rTFPI because clearance of rTFPI approaches liver blood flow. The aim of this study was to examine the effect of exercise-induced reduction in liver blood flow on the pharmacokinetics and pharmacodynamics of rTFPI., Methods: This was a two-way, open-label, randomized crossover study in eight healthy male volunteers. The subjects in both treatment groups received a continuous intravenous infusion of rTFPI (0.2 mg/kg/h) concurrently with intravenous sorbitol (50 mg/min) for 4 hours. Sorbitol was used as a biomarker for liver blood flow. The subjects were randomized to remain supine or to exercise on a bicycle ergometer for 30 minutes starting at the beginning of the third hour of the infusion., Results: Exercise reduced liver blood flow (mean +/- SEM) from 1.44 +/- 0.06 L/min to 0.40 +/- 0.03 L/min. The average clearance of rTFPI decreased from 0.73 +/- 0.04 L/min in the supine position to 0.25 +/- 0.02 L/min during exercise. This decrease in rTFPI clearance resulted in an 80% (95% confidence interval [CI], 60% to 102%) increase in plasma rTFPI levels during exercise. The average maximal prothrombin time and activated partial thromboplastin time values during exercise were 1.4 (95% CI, 0.4 to 2.5) and 4.4 (95% CI, 2.7 to 6.1) seconds higher compared with the supine steady-state level., Conclusions: Reduction in liver blood flow by exercise markedly increased rTFPI concentrations and induced a slight but variable prothrombin time and activated partial thromboplastin time increase at the rTFPI dose studied.

In this study, we demonstrate that two of the osmolytes utilized in the osmoconforming strategy of larval Culex tarsalis are regulated by two fundamentally different signals. When the external osmolality was increased using salinity (sea salts), hemolymph NaCl, proline and trehalose concentrations increased significantly. When sorbitol was used to increase the external osmolality without an elevation in salt concentration, hemolymph NaCl and proline concentrations decreased, whereas hemolymph trehalose concentration increased. The results suggest that proline accumulation was cued by increases in salinity, whereas trehalose levels followed increases in osmolality. Interestingly, we found that C. tarsalis larvae accumulated the exogenous sorbitol in the hemolymph in an osmoconforming manner. We conducted further studies in which changes in hemolymph NaCl concentrations were manipulated using changes in environmental salinity. The results suggested that hemolymph proline accumulation was cued by the proximal signal of hemolymph NaCl levels. Regardless of which solute (sea salts, sorbitol or mixtures thereof) was used to raise the external osmolality, trehalose accumulation tracked the increase in total osmolality of the medium. These findings indicate that the synthesis and accumulation of these two osmolytes are regulated by two independent signals.

Objective: To investigate the effect of Gui Xin Tong(GXT) on sorbitol and nerve conduction velocity in diabetic rats., Method: The model rats suffering from diabetes were induced by STZ, and blood sugar levels above 16 mmol/L were chosen for observation. The rats were divided into GXT group, AG group and control group. The nerve conduction velocity, aldose reductase activity and sorbitol in STZ induced diabetic rats were investigated., Result: Compared with the control group GXT could increase the sciatic nerve conduction velocity significantly (P < 0.05), decrease the RBC and sciatic nerve, aldose reductase activity, and RBC-sorbitol content., Conclusion: GXT has the effect of improving nerve conduction velocity significantly and reducing aldose reductase activity and sorbitol

Objective: To verify the effect of Jinmaitong composita (JMTC) on red blood cell aldolase reductase activity (RBC-AR), RBC sorbitol (RBC-S) and nerve conductive velocity in diabetic peripheral neuropathy (DN)., Methods: Sixty-six patients with DN were divided randomly into two groups, 33 patients in treated group treated with JMTC and 33 cases in the control group treated with Jinkui Shenqi (JKSQ), RBC-AR, RBC-S and nerve transmission speed were observed before and after three months treatment., Results: Level of RBC-AR, RBC-S apparently decreased and nerve conductive velocity increased (P < 0.05, P < 0.01) after TMTC treatment., Conclusion: JMTC was able to improve the nerve conduction significantly with a lowering of RBC-AR and RBC-S and has good result in treating Diabetic peripheral neurophathy.

Purpose: Determining which patients are at risk for the development of diabetic retinopathy is expected to greatly improve existing prevention and treatment options. In this study, using an animal model of diabetic retinopathy, the hypothesis was tested that magnetic resonance imaging (MRI) and a carbogen inhalation challenge provides important diagnostic information regarding the risk of developing diabetic retinopathy., Methods: MRI was used to measure noninvasively the change in oxygen tension along the entire inner retina (i.e., from superior ora serrata to inferior ora serrata) during a carbogen (95% O2/5% CO2) inhalation challenge (IOVS 1996;37:2089). Two animal groups were examined by this MRI method at two time points: (1) rats fed either normal rat chow (n = 20) or a 50% galactose diet (n = 20) for 3.5 months (i.e., before the appearance of extensive retinal lesions) or (2) rats fed either normal rat chow (n = 3) for 15 months or a 30% galactose diet (n = 4) for 15 to 18 months (i.e., when lesions are present). Retinal biochemical and morphometric measurements were also obtained., Results: After 3.5 months of galactosemia, before the appearance of extensive retinal morphologic lesions, a significant (P < 0.05) reduction in the panretinal oxygenation response was observed in the galactosemic group compared with its age-matched control. These galactose-fed animals also displayed a significantly (P < 0.05) larger oxygenation response in the inferior hemiretina than in the superior hemiretina. After 15 to 18 months of galactosemia, during the period when lesions are present, the panretinal oxygenation response remained significantly (P < 0.05) lower in the galactose-fed animals than in their age-matched controls. In contrast to the 3.5-month results, the oxygenation response in galactosemic animals at 15 to 18 months was significantly (P < 0.05) larger in the superior than in the inferior hemiretina. Hemiretinal oxygenation responses were not different in normal controls at either duration., Conclusions: MRI measurement of the retinal oxygenation response to a carbogen challenge appears to be a powerful new and noninvasive approach that may be useful for assessing aspects of pathophysiology underlying the development of diabetic retinopathy in galactosemic rats. These results support our working hypothesis and suggest that further research into the diagnostic potential of this MRI approach for predicting the development of diabetic retinopathy is warranted.

Assessment of hepatic function is based on both liver blood tests and functional tests, the extensive application of which is still controversial. The aim of this study was to evaluate the clinical utility of a few selected tests as discriminatory and prognostic indexes: serum albumin, pseudocholinesterase, prothrombin time, as well as galactose elimination capacity and hepatic sorbitol clearance. Two separate studies were performed: Study I to investigate how well these tests assessed severity, and Study II to evaluate their prognostic value. A total of 128 consecutive cirrhotic patients classified according to the Child-Pugh score were included in Study I; Study II was carried out on 47 of these 128 during a two-year follow-up period. Pairwise correlations between all tests and Child-Pugh score yielded higher significant values for liver blood tests than for the functional ones. In Study I functional tests such as galactose elimination capacity and hepatic sorbitol clearance did not appear to be better than conventional biochemical tests in discriminating clinical severity of cirrhotic patients, as defined by Child-Pugh classification. Results of Study II confirmed that in severe liver cirrhosis Child-Pugh score remains the best method for medium- and long-term prognosis and for planning liver transplantation. Functional tests should be reserved for defining the residual functioning liver mass or for studies about functional liver plasma flow.

Two types of retinopathy, diabetic and pigmentary, may be seen in subjects with maternal inheritance diabetes and deafness. The potential for interactions between the two retinopathies has not been explored. The mitochondrial mutation may affect development of diabetic retinopathy in subjects with MIDD by altering normal pathways of glucose metabolism. We identified five unrelated MIDD kindreds with 61 living maternal line family members. Twenty-three of the family members, 12 with diabetes mellitus and 11 without volunteered to be studied. Subjects were graded for severity of diabetic retinopathy and presence or absence of pigmentary retinopathy after slit lamp biomicroscopy, retinal photography of seven standard fields and fluorescein angiography. Blood was taken, in the fasted state, from MIDD subjects (duration of diabetes 17.0+/-6.9 yr) and non-diabetic subjects with the mutation, for assay of sorbitol and glucose and values compared with diabetic and non-diabetic control subjects without the mutation. Diabetic retinopathy was absent in 9/12 subjects (75%), with 3 having mild non-proliferative retinopathy. No one had cataract. Red blood cell sorbitol levels, adjusted for ambient blood glucose, were significantly lower in MIDD subjects compared with diabetic subjects (1.16+/-0.5 cf. 2.03+/-1.1, x 10(-3) g mmol(-1), p=0.04). Pigmentary retinopathy was present in 15 of 23 subjects, of whom 13 had some abnormality of glucose tolerance. Abnormal glucose tolerance was strongly associated with the development of pigmentary retinopathy (odds ratio 19.5, p=0.008). In conclusion, there appears to be a decreased prevalence of diabetic retinopathy and cataract in MIDD, which we propose is due to reduced glucose metabolism by the polyol pathway. Abnormal glucose tolerance increases the clinical expression of pigmentary retinopathy in subjects with a mitochondrial genome mutation. A greater understanding of the metabolic effects of mitochondrial DNA mutations has the potential to give insight into the mechanisms of diabetic retinopathy and other complications of diabetes mellitus.

Objective: To clarify the influence of interindividual difference in the level of aldose reductase on the polyol pathway-related metabolism in diabetic patients., Research Design and Methods: The enzyme protein content was determined by a two-site enzyme-linked immunosorbent assay using monoclonal and polyclonal antibodies to recombinant human aldose reductase in erythrocytes from 35 diabetic patients and 11 healthy volunteers. Patients were stratified into two groups by the median of aldose reductase content, and the erythrocyte sorbitol level, the fructose level, and the lactate-to-pyruvate ratio were compared between the two groups. We also examined the correlation of the enzyme content with these metabolic parameters., Results: The group of patients whose enzyme content was above the median showed a significant increase in the levels of sorbitol (34.7 +/- 4.9 vs. 20.4 +/- 2.0 nmol/g Hb, P < 0.05) and fructose (99.8 +/- 17.2 vs. 45.9 +/- 4.6 nmol/g Hb, P < 0.05), along with an elevated lactate-to-pyruvate ratio (28.6 +/- 6.1 vs. 11.7 +/- 1.2, P < 0.05), compared with patients with low enzyme levels. The aldose reductase content in erythrocytes was well correlated with its activity, and there was a significant correlation between the enzyme content and the erythrocyte sorbitol (r = 0.58, P < 0.001) or fructose (r = 0.57, P < 0.001) levels as well as between the enzyme level and the lactate-to-pyruvate ratio (r = 0.38, P < 0.05)., Conclusions: These results suggest that the interindividual variability of aldose reductase content may contribute tangibly to the polyol-pathway flux and cytoplasmic redox alteration in diabetic patients.

Samples for use in the fluorometric enzymatic assay of sorbitol in erythrocytes are normally prepared using HClO4 and K2CO3. We have replaced these reagents with NaOH and ZnSO4. Human whole blood, erythrocyte and plasma samples prepared with NaOH and ZnSO4 are colorless and clear, while erythrocyte samples prepared with HClO4 and K2CO3 are a pale yellow-brown color. The sorbitol dehydrogenase reaction in the supernatant of the mixture of NaOH and ZnSO4 is inhibited, but ethylenediaminetetraacetate completely eliminates this effect. The sorbitol assay in erythrocytes prepared with NaOH and ZnSO4 shows higher sensitivity and reproducibility than did that with HClO4 and K2CO3. Recovery of sorbitol added to erythrocytes is similar in both assay methods. Concentrations of whole blood and erythrocyte sorbitol assayed by the present method are significantly higher in diabetics than in normals. Poorly controlled diabetics had higher whole blood and erythrocyte sorbitol than well-controlled diabetics. Whole blood sorbitol concentrations differed more between diabetic and normal subjects than did erythrocyte sorbitol concentrations.