Effects of 4G-beta-D-Galactosylsucrose in patients with depression: A randomized, double-blinded, placebo-controlled, parallel-group comparative study

Advances in genetic research on microbiome have led to several trials on the effectiveness of synbiotics or probiotics in patients with depression; however, none have evaluated the efficacy of prebiotics. 4G-beta-D-Galactosylsucrose (Lactosucrose, LS) is selectively assimilated by Bifidobacterium as a prebiotic and improves microbiome diversity. However, as it is not clear if LS consumption can improve symptoms of depression, we investigated whether LS intake can improve depressive symptoms, quality of life (QOL), and self-efficacy by conducting a single cite, double-blinded, randomized controlled trial in 20 outpatients with depressive episodes (F32, ICD-10) for 24 weeks. Participants (age range, 36-72 years) were randomized to the LS (n = 9) or placebo groups (n = 11). Primary outcome was improvement in total Montgomery Asberg Depression Rating Scale (MADRS) score, and the secondary outcomes were MADRS subscores, global self-efficacy scale (GSES) score, World Health Organization QOL (WHO/QOL-26) score, and 16S rRNA analysis of the fecal microbiome. LS consumption did not significantly improve total MADRS scores (-2 (-16 to 16) vs 0 (-6 to 10), p = 0.552), but GSES tended to improve in the LS group (2.00 ± 4.24 vs -1.36 ± 4.15, p = 0.091) with a large effect size (Cohen's d = 0.802). Sequencing of 16S rRNA revealed individual-level differences in microbiome diversity changes due to the intervention. Thus, we show that LS intake can improve self-efficacy, but not depressive symptoms, even in a small sample. Additional studies that also regulate diet and ensure adherence may help determine a correlation between depression and the gut microbiome.

Adipose extracellular signal-regulated kinase 2 protected from endothelial dysfunction and the oxidative stress of perivascular adipose tissue in obese mice

Introduction

Extracellular signal-regulated kinase (ERK) modulates differentiation and maturation of adipocyte and the hypertrophy and differentiation of adipocytes affected the vascular diseases in obese. Changes in characters of adipocytes could develope the oxidative stress and inflammations. Moreover, changes in perivascular adipose tissue (PVAT) could modulate vascular tonus in obesity. However, the role of adipose ERK2 in endothelial function and characters of PVAT in obese in vivo had not been clarified, yet.

Purpose

This study aims to elucidate the role of the adipose ERK2 in endothelial-dependent relaxation (EDR) in mice model of obesity. The role of PVAT in EDR was also assessed.

Methods and results

We created adipose-specific ERK2 knock out mice (AE2KO) by crossing fatty acid binding protein 4 Cre and ERK2 flox mice and fed them with normal diet (ND) or high fat/ high sucrose diet (HFHSD) for 24 weeks. AE2KO fed with HFHSD gained more weight and revealed the heterogeneity in sizes of adipocyte in subcutaneous fat (SF). Furthermore, the mRNA levels of lipoprotein lipase, hormone-sensitive lipase, and peroxisome proliferator-activated receptor γ, which was the master genes of adipocyte differentiation, were markedly down-regulated in SF. PVAT in AE2KO with HFHSD was markedly enlarged and the mRNA expression of inflammatory adipocytokines, such as IL-1β and leptin were up-regulated. Next, we assessed EDR by acetylcholine (ACh) -induced relaxation in aortic rings with or without PVAT. EDR without PVAT was modestly decreased in AE2KO with HFHSD compared with wild type mice (WT) with HFHSD. Aortic rings with PVAT increased EDR in WT with ND. PVAT modestly decreased EDR in WT with HFHSD and mostly eliminated EDR in AE2KO with HFHSD. To assess the contraction factors released from PVAT, the solutions incubated with PVAT (SIP) were transferred to the normal aortic rings. SIP from WT with HFHSD mildly increased vascular tone and SIP from AE2KO with HFHSD further increased it. Tempol, which was superoxide scavenger, restored endothelial dysfunction with PVAT and suppressed the contraction with SIP from AE2KO with HFHSD. Fluorescence intensity of dihydroethidium stain of aorta and PVAT, which indicated that aortic and adipose superoxide production were elevated in AE2KO with HFHSD, which were mostly eliminated with tempol.

Conclusions

Adipose ERK2 selectively modulated differentiation in SF, suppressed the aortic oxidative stress and protected from endothelial dysfunction in obese. Moreover, adipose ERK2 suppressed the hypertrophy, inflammation, and oxidative stress of PVAT in obese. The oxidative stress with the inflammation in PVAT released vasoconstriction factors, which contributed to endothelial dysfunction in obese mice.

Figure 1

Funding Acknowledgement

Type of funding source: None

739SERCA2 Cys674 modification lead to ventricular arrhythmia due to impaired sarcoplasmic reticulum Ca2+ handling

Background

Sarcoplasmic reticulum Ca2+-ATPase2 (SERCA2) plays an important role in intracellular Ca2+ handling. Under pathological conditions, oxidative stress leads to irreversible oxidation of Cys674 on SERCA2 which causes intracellular Ca2+ overload. Intracellular Ca2+ overload is known as the cause of ventricular arrhythmia, but the relation between SERCA2 function and ventricular arrhythmia remains unclear.

Purpose

To investigate the role of Cys674 on SERCA2 in the intracellular Ca2+ handling and the induction of ventricular arrhythmia.

Methods

We employed SERCA2 Cys674Ser heterozygote knock-in mice (SKI) which mimics oxidative modification of Cys674 on SERCA2. Continuous infusion of angiotensin (ANG) (3mg/kg/day) or distilled water were performed both in wild type mice (WT) and SKI for a week. After 1 week, electrophysiological study and intracellular Ca2+ transient measurement were performed.

Results

ANG elevated blood pressure and represented cardiac hypertrophy with fibrosis similarly both in WT and SKI. The mRNA expression of calcium/calmodulin-dependent protein kinase-II (CaMKII), ryanodine receptor (RyR) and sodium-calcium exchanger (NCX) was increased in SKI heart compared with WT. QTc interval was prolonged in SKI compared with WT, which was markedly prolonged with ANG infusion. Under programmed electrical stimulation, only SKI with ANG showed high incidence of pacing induced ventricular arrhythmia (0/11 in WT/SKI control, 0/14 in WT with ANG vs. 8/14 in SKI with ANG, P < 0.01). In Ca2+ transient measurement, the peak Ca2+ transient amplitude (F/F0) was decreased (WT: 1.81 vs. SKI: 1.46, P < 0.01) and the time to 50% of cytosolic Ca2+ extrusion (T50) was prolonged (WT: 152.6ms vs. SKI: 202.3ms, P < 0.05) in SKI with ANG, suggesting decreased sarcoplasmic reticulum Ca2+ content and impaired SERCA2 activity in SKI with ANG. Intraperitoneal administration of dantrolene sodium (DAN) which inhibit Ca2+ leakage from RyR receptor normalized decreased F/F0 and prolonged T50 in SKI with ANG (Fig. 1 A, B). DAN also prevented QTc prolongation and decreased the incidence of ventricular arrhythmia in SKI with ANG (8/14 in SKI with ANG vs. 2/13 in SKI with ANG + DAN, P < 0.05) (Fig. 2).

Conclusions

The loss of thiol on Cys674 under pathological condition resulted in impaired Ca2+ handling and high incidence of ventricular arrhythmia which were ameliorated by inhibition of Ca2+ leakage through RyR. Oxidative modification of Cys674 on SERCA2 might contribute to Ca2+ mishandling and arrhythmogenesis.

Abstract Figure.

4G-β-D-galactosylsucrose as a prebiotics may improve underweight in inpatients with schizophrenia

Japanese inpatients with schizophrenia have a higher mortality risk due to underweight compared with the general population. The aim of this study was to investigate the effect of 4^G-β-D-galactosylsucrose on body weight in underweight schizophrenia inpatients. The study population consisted of 5 male and 11 female subjects aged 63.0 ± 10.9 years. The subjects had ingested 3.0 g/day 4^G-β-D-galactosylsucrose for 6 months. BMI increased significantly, from 20.9 ± 3.7 kg/m² to 22.3 ± 4.3 kg/m², and this was accompanied by a significant increase in Bifidobacterium in the fecal microbiota, which increased from 16.1 ± 12.6% to 21.5 ± 13.9%. Although 4^G-β-D-galactosylsucrose appears to have no significant effects on nutritional indicators such as serum albumin, it may alleviate underweight in inpatients with schizophrenia. Body weight may be related to fecal microbiota composition.

Studies on peroxidized lipids. V. Formation and characterization of 1,4-dihydropyridine-3,5-dicarbaldehydes as model of fluorescent components in lipofuscin

We investigated fluorescence properties of 1,4-dihydropyridine-3,5-dicarbaldehydes and their formation in mild reaction of primary amines and malonaldehyde, in order to clarify the role of malonaldehyde in the formation of fluorescent components of lipofuscin. The compounds exhibited fluorescence with excitation maxima at 375-405 nm and emission maxima at 435-465 nm, which was similar to those of lipofuscin and the fluorescent substances derived from the reaction of oxidized fatty acids with primary amines. Fluorescence of the compounds was greatly affected in acidic medium and little influenced in alkaline medium or by the metal chelator. The compounds lost fluorescence by treatment with sodium borohydride. They were inert to thiobarbituric acid reaction. Some of the fluorescence properties of the compounds were different from those of lipofuscin and the related fluorescent substances. Mild reaction of methylamine with pure malonaldehyde gave a single fluorescent compound, 1,4-dimethyl-1,4-dihydropyridine-3,5-dicarbaldehyde (Ia), and the reaction with the acid hydrolysate of tetramethoxypropane gave Ia and 1-methyl-4-(dimethoxyethyl)-1,4-dihydropyridine-3,5-dicarbaldehyde (IIa), the latter being produced from the impurity in the hydrolysate. These reactions produced a non-fluorescent Schiff base, a 1∶1-adduct of methylamine and malonaldehyde (IIIa), as a major product. It looks unlikely that malonaldehyde is the only product of lipid oxidation that produces fluorescent components in lipofuscin complex.

Numerical simulation of microstructure formation of suspended particles in magnetorheological fluids

Microstructure formation of magnetic particles and nonmagnetic particles in magnetorheological (MR) fluids is investigated using the particle method simulation based on simplified Stokesian dynamics. Spherical nonmagnetic particles are rearranged in the field direction due to the formation of magnetic particles in chain-like clusters. Cluster formation of spherocylindrical magnetic particles forces spherical nonmagnetic particles to arrange in the direction of the field. In contrast, the spherocylindrical nonmagnetic particles, with an aspect ratio of two or three, are not sufficiently rearranged in the field direction by cluster formation of spherical magnetic particles. Even after cluster formation in the presence of a magnetic field, the uniformity of distribution of particles on the plane perpendicular to the field direction shows very little change. However, the deviation of uniformity in particle distribution is reduced when the volume fraction of magnetic particles is the same as that of nonmagnetic particles.

CIRCULATING IMMUNITY PRINCIPLES IN RAT-BITE FEVER

Summarizing the results that have been cited, we have proved that the blood serum of convalescents from rat-bite fever contains antibodies which are specific against the causative agent of that disease. The serum of rat-bite fever was capable of destroying the spirochetes not only in the hanging drop preparations, but also in the peritoneal cavity of guinea pigs. The guinea pigs employed for Pfeiffer's test always remained well. In the experimentally infected mice receiving intravenously or intraperitoneally serum equalling in quantity the amount of infected blood, the numbers of spirochetes were greatly decreased or they disappeared for a definite period. It is not yet clear how long after recovery from rat-bite fever the antibodies are effective in the blood of human beings, and further investigations are needed to elucidate this point. In our experiments we found that serum taken from Case I showed definite spirochetolytic and spirocheticidal properties 11 months after the onset of the disease. In Case 2, the period was 6 months, and in Case 3, 3 months following the onset of rat-bite fever.

SPIROCHAETA HEBDOMADIS, THE CAUSATIVE AGENT OF SEVEN DAY FEVER (NANUKAYAMI) : FIRST PAPER

A new species of spirochete which we have called Spirochæta hebdomadis has been described as the specific etiological agent of seven day fever, a disease prevailing in the autumn in Fukuoka and other parts of Japan. This spirochete is distinguishable from Spirochæta icterohæmorrhagiæ to which it presents certain similarities. Young guinea pigs are susceptible to inoculation with the blood of patients and to pure cultures of the spirochete, and those developing infection exhibit definite symptoms suggestive of those of seven day fever in man. The blood serum of convalescents from seven day fever contains specific immune bodies acting spirochetolytically and spirocheticidally against the specific spirochetes, but not against Spirochæta icterohæmorrhagiæ. The field mouse (Microtus montebelli) is the normal host of the spirochetes, which have been detected in the kidneys and urine of 3.3 per cent of the animals examined. The endemic area of prevalence of seven day fever corresponds with the region in which field mice abound.

THE RAT AS A CARRIER OF SPIROCHAETA ICTEROHAEMORRHAGIAE, THE CAUSATIVE AGENT OF WEIL'S DISEASE (SPIROCHAETOSIS ICTEROHAEMORRHAGICA)

1. On the basis of these findings, we conclude that the extermination of rats and field mice is a highly important prophylactic measure against Weil's disease. 2. The chemical composition of soil and water plays animportant part in the development of Spirochœta icterohœmorrhagiœ, and consequently in the spread of the disease of which it is the causative agent.

THE PROPHYLAXIS OF WEIL'S DISEASE (SPIROCHAETOSIS ICTEROHAEMORRHAGICA)

We have already described briefly the portals of entry and of excretion of the pathogenic spirochetes. We may mention here that we have twice prevented epidemics by disinfection of the ground and the removal of the inundated water in certain places in coal mines. In one mine 19 out of 50 workmen, and in another 9 out of 30 workmen came down with Weil's disease in about 2 weeks. We have already pointed out that the period during which the pathogenic spirochetes are excreted in the urine continues, as a rule, for 40 days, and that we must, therefore, apply disinfection for at least 40 days after the first appearance of the disease. Lately we have found that in 21 cases out of 24 the spirochetes were excreted in the urine for 40 days, in one case until the 42nd day, in one case until the 45th day, and in still another case until the 63rd day. Another important fact concerning the prophylaxis which has been brought out is that both house and ditch rats (brown) carry virulent Spirochaeta icterohamorrhagae, the causal spirochete of Weil's disease, in their kidneys. Miyajima has reported that field rats have the pathogenic organisms in their kidneys; he will report these findings in detail later. The spirochetes which he described are less virulent than ours. On his advice we have carefully examined house and ditch rats in the city and rats in the coal mines of Kyushu, where Weil's disease prevails, and found that 39.5 per cent carried highly virulent pathogenic spirochetes in their kidneys, thus confirming Miyajima's experiments. The kidneys were examined microscopically under the dark-field microscope, and in the cases in which we did not find the pathogenic spirochete, we made inoculations into guinea pigs. Thus we found Spirochaeta icterohaemorrhagiae microscopically in the kidneys or in the urine in 32.4 per cent, and by means of inoculation in 7 per cent, making a total of 39.5 per cent carrying the pathogenic organisms, out of a total number of 86 rats examined. In some instances, rats were made to bite guinea pigs and in two instances caused Weil's disease. Among fifty-five patients in our clinic, twelve were cooks; and in Europe many cases arise among butchers-indicating the relation of the disease to rats. Moreover, during the present year we observed two patients who acquired Weil's disease, one in 1 week, the other 8 to 9 days after they had been bitten by rats. These facts point to a relation between Weil's disease and rats. The infection is transmitted probably from rats to man by means of the urine of the rats, directly or indirectly. On the injection of 0.1 gm. of rat urine which contains Spirochaeta icterohaemorrhagiae into the peritoneal cavity of guinea pigs, the infection arises, while the injection of the liver or the blood of the rats into guinea pigs does not produce the typical disease. The finding that the kidneys of rats contain the pathogenic organisms of the disease is important from the point of view of prophylaxis. The large number of rats in the trenches of the European battle-fields suggests the possibility that many cases of Weil's disease may arise. We shall report on this point in more detail later.

THE SERUM TREATMENT OF WEIL'S DISEASE (SPIROCHAETOSIS ICTEROHAEMORRHAGICA)

Horses immunized with cultures of Spirochæta icterohæmorrhagiæ yield an immune serum having therapeutic properties. With rare exceptions the serum destroys completely the spirochetes contained in the circulating blood. The development of antibodies is promoted by the serum injections. The number of spirochetes in the organs is reduced by the treatment. Secondary manifestations due to the serum are slight and disappear promptly. The ultimate effects of the serum treatment on the symptoms and final outcome of the disease have still to be determined.

Inactivation of AMPK alters gene expression and promotes growth of prostate cancer cells

AMP-activated protein kinase (AMPK) serves as a fuel-sensing enzyme that is activated by binding of AMP and subsequent phophorylation by upstream kinases such as the tumor suppressor LKB1, when cells sense an increase in the ratio of AMP to ATP. Acute activation of AMPK stimulates fatty acid oxidation to generate more ATP and simultaneously inhibits ATP-consuming processes including fatty acid and protein syntheses, thereby preserving energy for acute cell surviving program, while the chronic activation leads to inhibition of cell growth. The goal of the present study is to explore the mechanisms by which AMPK regulates cell growth. Toward this end, we established stable cell lines by introducing a dominant negative mutant of AMPK α1 subunit or its shRNA into the prostate cancer C4-2 cells and other cells, or wild type LKB1 into the lung adenocarcinoma A549 and breast MB-MDA-231 cancer cells, both of which lack functional LKB1. Our results showed that the inhibition of AMPK accelerated cell proliferation and promoted malignant behavior such as increased cell migration and anchorage-independent growth. This was associated with decreased G1 population, downregulation of p53 and p21, and upregulation of S6K, IGF-1 and IGF1R. Conversely, treatment of the C4-2 cells with 5-aminoimidazole-4-carboxamide 1-Dribonucleoside (AICAR), a prototypical AMPK activator, caused opposite changes. In addition, our study using microarray and RT-PCR revealed that AMPK regulated gene expression involved in tumor cell growth and survival. Thus, our study provides novel insights into the mechanisms of AMPK action in cancer cells and presents AMPK as an ideal drug target for cancer therapy.

Japanese version of the Frontal Assessment Battery for dementia

The Frontal Assessment Battery (FAB) was developed as a short bedside cognitive and behavioral battery to assess frontal lobe functions. The purpose of this study was to evaluate the validity and reliability of a Japanese version of the FAB to measure cognitive dysfunction in patients with dementia. We studied 25 normal subjects and 105 patients with Alzheimer's disease, n=58, vascular dementia, n=24, and frontotemporal dementia, n=23. The neuropsychological test battery included the FAB, the Mini Mental State Examination (MMSE), a memory test, and the Wisconsin Card Sorting Test (Keio version: KWCST). Patients with dementia performed significantly more poorly than controls on all tests. The FAB showed a good correlation with other cognitive measures: MMSE (r=0.725), KWCST number of categories completed (r=0.654), KWCST number of perseveration errors (r=-0.484), and memory test (r=0.643). Patients with more severe Clinical Dementia Rating scores showed lower scores on the FAB. There was good inter-rater reliability (r=0.972), test-retest reliability (r=0.769), and internal consistency (Cronbach's coefficient alpha=0.715). The FAB is a valid and reliable screening test to evaluate cognitive dysfunction among patients with dementia.

Human N-acetylglucosaminyltransferase I. Expression in Escherichia coli as a soluble enzyme, and application as an immobilized enzyme for the chemoenzymatic synthesis of N-linked oligosaccharides

N-Acetylglucosaminyltransferase I (GnT-I), which catalyzes the transfer of an N-acetylglucosamine residue from UDP-N-acetylglucosamine to the alpha1,3-linked mannose on Man5GlcNAc2 (M5), is a critical enzyme for the synthesis of high-mannose-type to complex-type glycan structures in N-linked glycan processing. We developed a large-scale preparation system for recombinant human GnT-I (hGnT-I) using the maltose binding protein (MBP) fusion system to facilitate the chemoenzymatic route for complex-type N-linked glycan synthesis. MBP-fused GnT-I was purified by affinity chromatography on an amylose resin column. The relative activity of MBP-fused GnT-I toward high-mannose-type N-linked oligosaccharides was 100% for Man5GlcNAc2, 52% for Man3GlcNAc2, 17% for Man6GlcNAc2. MBP-fused GnT-I exhibited optimal activity at pH 6.5-9.5 and was more active between pH 6.5-9.0. The optimum temperature for MBP-fused GnT-I activity was 40 degrees C, but the enzyme was active between 0-70 degrees C. Mn2+ and Co2+ were critical for the enzyme activity, while Zn2+ and Ca2+ inhibited the activity. Kinetic analysis of the purified enzyme showed an apparent K(m) value of 0.483 mM and a V(max) of 101 nmol/mg/min for M5. Immobilization of MBP-fused GnT-I on the amylose resin led to an 80% yield of the high mannose-type-of oligosaccharide.

Memory function decline over 18 months after selective amygdalohippocampectomy

We report on a 22 year-old woman with left temporal lobe epilepsy who had suffered complex partial seizures since childhood. At 19 years 10 months of age she underwent selective amygdalohippocampectomy, which resulted in a complete cessation of seizures. Preoperatively, the Logical Memory II section of the WMS-R revealed poor logical memory function. Postoperatively, the patient's scores on several neuropsychological tests had deteriorated, namely, the Miyake Paired-Associate Word Learning Test (related and unrelated pairs), several sections of the WMS-R (Figural Memory, Logical memory I, Visual Reproduction II, Visual Paired Associates I, and Verbal Paired Associates I and II), and the BVRT-R. In particular, her scores on the Visual Paired Associates I, Verbal Paired Associates I and II sections of the WMS-R, and the BVRT-R not only declined at one and three months post-surgery, but also showed progressive deterioration at 16 and 18 months post-surgery. It should be kept in mind that selective amygdalohippocampectomy can result in progressive postoperative, deterioration in some aspects of memory function.

Malonyl-CoA and AMP-activated protein kinase (AMPK): possible links between insulin resistance in muscle and early endothelial cell damage in diabetes

Based on available evidence, we would propose the following. (i) Excesses of glucose and free fatty acids cause insulin resistance in skeletal muscle and damage to the endothelial cell by a similar mechanism. (ii) Key pathogenetic events in this mechanism very likely include increased fatty acid esterification, protein kinase C activation, an increase in oxidative stress (demonstrated to date in endothelium) and alterations in the inhibitor kappa B kinase/nuclear factor kappa B system. (iii) Activation of AMP-activated protein kinase (AMPK) inhibits all of these events and enhances insulin signalling in the endothelial cell. It also enhances insulin action in muscle; however, the mechanism by which it does so has not been well studied. (iv) The reported beneficial effects of exercise and metformin on cardiovascular disease and insulin resistance in humans could be related to the fact that they activate AMPK. (v) The comparative roles of AMPK in regulating metabolism, signalling and gene expression in muscle and endothelial cells warrant further study.

Inhibition of sorbitol dehydrogenase exacerbates autonomic neuropathy in rats with streptozotocin-induced diabetes

We have developed an animal model of diabetic autonomic neuropathy that is characterized by neuroaxonal dystrophy (NAD) involving ileal mesenteric nerves and prevertebral sympathetic superior mesenteric ganglia (SMG) in chronic streptozotocin (STZ)-diabetic rats. Studies with the sorbitol dehydrogenase inhibitor SDI-158, which interrupts the conversion of sorbitol to fructose (and reactions dependent on the second step of the sorbitol pathway), have shown a dramatically increased frequency of NAD in ileal mesenteric nerves and SMG of SDI-treated versus untreated diabetics. Although lesions developed prematurely and in greater numbers in SDI-treated diabetics, their distinctive ultrastructural appearance was identical to that previously reported in long-term untreated diabetics. An SDI effect was first demonstrated in the SMG of rats that were diabetic for as little as 5 wk and was maintained for at least 7.5 months. As in untreated diabetic rats, rats treated with SDI i) showed involvement of lengthy ileal, but not shorter, jejunal mesenteric nerves; ii) demonstrated NAD in paravascular mesenteric nerves distributed to myenteric ganglia while sparing adjacent perivascular axons ramifying within the vascular adventitia; and, iii) failed to develop NAD in the superior cervical ganglia (SCG). After only 2 months of SDI-treatment, tyrosine hydroxylase immunolocalization demonstrated marked dilatation of postganglionic noradrenergic axons in paravascular ileal mesenteric nerves and within the gut wall versus those innervating extramural mesenteric vasculature. The effect of SDI on diabetic NAD in SMG was completely prevented by concomitant administration of the aldose reductase inhibitor Sorbinil. Treatment of diabetic rats with Sorbinil also prevented NAD in diabetic rats not treated with SDI. These findings indicate that sorbitol pathway-linked metabolic imbalances play a critical role in the development of NAD in this model of diabetic sympathetic autonomic neuropathy.

Evidence as a HIV-1 self-defense vaccine of cyclic chimeric dodecapeptide warped from undecapeptidyl arch of extracellular loop 2 in both CCR5 and CXCR4

Novel conformation-specific antibodies were raised against a cyclic chimeric dodecapeptidyl multiple antigen peptide (cCD-MAP) constructed with a spacer-armed Gly-Asp dipeptide and two pentapeptides (S(169)-Q(170)-K(171)-E(172)-G(173) of CCR5 and E(179)-A(180)-D(181)-D(182)-R(183) of CXCR4) which are components of the undecapeptidyl arch (UPA: from R(168) to C(178) in CCR5, from N(176) to C(186) in CXCR4) of extracellular loop 2 (ECL2) in chemokine receptors (CCR5 and CXCR4). Of the antibodies raised, one monoclonal antibody, CPMAb-I (IgMkappa), reacted with cCD-MAP, but not with the linear chimeric dodecapeptide-MAP. The antibody reacted with the cells separately expressing CCR5 or CXCR4, but not with those not expressing the coreceptors. Moreover, the antibody markedly suppressed infection by X4, R5, or R5X4 virus in a dose-dependent manner in a new phenotypic assay for drug susceptibility of HIV-1 using CCR5-expressing Hela/CD4(+) cell clone 1-10 (MAGIC-5). Moreover, CPMAb-I interfered with LAV-1(BRU) infection (m.o.i. = 0.01) of Molt4#8 cells cocultured with CPMAb-I-producing hybridoma in the transwell, and significantly interfered with neither chemotaxis nor calcium influx induced with stromal cell-derived factor 1 alpha (SDF-1alpha). Thus, the antibody raised against the cCD-MAP provides powerful protection or defense against HIV-1 infection. We therefore propose the cCD-MAP or its derivative immunogen as a novel candidate for an HIV-1 coreceptor-based self-defense vaccine.

Vascular dysfunction induced by AGE is mediated by VEGF via mechanisms involving reactive oxygen species, guanylate cyclase, and protein kinase C

OBJECTIVE

These experiments were designed to elucidate mechanisms mediating vascular dysfunction induced by advanced glycation end products (AGEs).

METHODS

Skin chambers were mounted on the backs of Sprague-Dawley rats and 1 week later, granulation tissue that formed in the bottom of the chamber was exposed twice daily for 7 days to glycated rat serum albumin in the presence and absence of inhibitors of reactive oxygen intermediates, nitric oxide synthase and guanylate cyclase, protein kinase C (PKC), and a neutralizing vascular endothelial growth factor (VEGF) antibody. Vascular (125)I-albumin clearance and blood flow were quantified by use of a double isotope-dilution technique and radiolabeled microspheres, respectively.

RESULTS

Albumin permeation and blood flow were increased dose-dependently to a maximum of 2 to 3 times controls by increasing the extent of glucose modification, the concentration, or the duration of exposure to glycated albumin. These increases were significantly attenuated by probucol and superoxide dismutase; N(G)-nitro-L-arginine-methyl ester (L-NAME), a nitric oxide synthase inhibitor; LY83583, a guanylate cyclase inhibitor; and LY333531, a beta-isoform-selective protein kinase C inhibitor. A neutralizing VEGF monoclonal antibody also markedly attenuated the permeability and blood flow increases induced by glycated albumin.

CONCLUSIONS

These observations indicate potentially important roles for oxygen free-radicals and nitric oxide in mediating permeability and blood flow changes induced by glycated proteins via mechanisms involving increased protein kinase C activity and VEGF production. Striking similarities in the mechanism by which hyperglycemia and glycated proteins induce vascular dysfunction suggest that a common pathway mediates effects of these different metabolic imbalances on vascular dysfunction.

Acute regulation of fatty acid oxidation and amp-activated protein kinase in human umbilical vein endothelial cells

It is generally accepted that endothelial cells generate most of their ATP by anaerobic glycolysis and that very little ATP is derived from the oxidation of fatty acids or glucose. Previously, we have reported that, in cultured human umbilical vein endothelial cells (HUVECs), activation of AMP-activated protein kinase (AMPK) by the cell-permeable activator 5-aminoimidazole-4-carboximide riboside (AICAR) is associated with an increase in the oxidation of (3)H-palmitate. In the present study, experiments carried out with cultured HUVECs revealed the following: (1) AICAR-induced increases in palmitate oxidation during a 2-hour incubation are associated with a decrease in the concentration of malonyl coenzyme A (CoA) (an inhibitor of carnitine palmitoyl transferase 1), which temporally parallels the increase in AMPK activity and a decrease in the activity of acetyl CoA carboxylase (ACC). (2) AICAR does not stimulate either palmitate oxidation when carnitine is omitted from the medium or oxidation of the medium-chain fatty acid octanoate. (3) When intracellular lipid pools are prelabeled with (3)H-palmitate, the measured rate of palmitate oxidation is 3-fold higher, and in the presence of AICAR, it accounts for nearly 40% of calculated ATP generation. (4) Incubation of HUVECs in a glucose-free medium for 2 hours causes the same changes in AMPK, ACC, malonyl CoA, and palmitate oxidation as does AICAR. (5) Under all conditions studied, the contribution of glucose oxidation to ATP production is minimal. The results indicate that the AMPK-ACC-malonyl CoA-carnitine palmitoyl transferase 1 mechanism plays a key role in the physiological regulation of fatty acid oxidation in HUVECs. They also indicate that HUVECs oxidize fatty acids from both intracellular and extracellular sources, and that when this is taken into account, fatty acids can be a major substrate for ATP generation. Finally, they suggest that AMPK is likely to be a major factor in modulating the response of the endothelium to stresses that alter its energy state.

Hopeafuran and a C-glucosyl resveratrol isolated from stem wood of Hopea utilis

A new resveratrol dimer and a new C-glucosyl resveratrol were isolated from stem wood of Hopea utilis along with nine stilbenoid derivatives comprising bergenin and (+)-lyoniresinol. The structures have been elucidated on the basis of the spectroscopic evidence.

Four new stilbenoid C-glucosides isolated from the stem bark of Shorea hemsleyana

Four new C-glucopyranosides of resveratrol oligomers, hemsleyanosides A-D, were isolated from the bark of Shorea hemsleyana. The structures were established on the basis of spectroscopic evidence, including 1H-1H and 1H-13C long-range couplings and nuclear Overhauser effect experiments in the NMR spectrum.

Stilbenoids isolated from stem bark of Shorea hemsleyana

Two new stilbene glucosides [(+)-alpha-viniferin 13b-O-beta-glucopyranoside and resveratrol 12-C-beta-glucopyranoside] and two new resveratrol oligomers, hemsleyanols A and B, were isolated from the bark of Shorea hemsleyana along with four known resveratrol oligomers. The structures of the isolates, including the relative configurations, were established by spectroscopic data involving long-range coupling and nuclear Overhauser effect experiments.

Energy metabolism in uncoupling protein 3 gene knockout mice

Uncoupling protein 3 (UCP3) is a member of the mitochondrial anion carrier superfamily. Based upon its high homology with UCP1 and its restricted tissue distribution to skeletal muscle and brown adipose tissue, UCP3 has been suggested to play important roles in regulating energy expenditure, body weight, and thermoregulation. Other postulated roles for UCP3 include regulation of fatty acid metabolism, adaptive responses to acute exercise and starvation, and prevention of reactive oxygen species (ROS) formation. To address these questions, we have generated mice lacking UCP3 (UCP3 knockout (KO) mice). Here, we provide evidence that skeletal muscle mitochondria lacking UCP3 are more coupled (i.e. increased state 3/state 4 ratio), indicating that UCP3 has uncoupling activity. In addition, production of ROS is increased in mitochondria lacking UCP3. This study demonstrates that UCP3 has uncoupling activity and that its absence may lead to increased production of ROS. Despite these effects on mitochondrial function, UCP3 does not seem to be required for body weight regulation, exercise tolerance, fatty acid oxidation, or cold-induced thermogenesis. The absence of such phenotypes in UCP3 KO mice could not be attributed to up-regulation of other UCP mRNAs. However, alternative compensatory mechanisms cannot be excluded. The consequence of increased mitochondrial coupling in UCP3 KO mice on metabolism and the possible role of yet unidentified compensatory mechanisms, remains to be determined.

Stilbenoids in the stem bark of Hopea parviflora

From the bark of Hopea parviflora, two stilbenoids, named (+)-parviflorol and (-)-ampelopsin A, were isolated in addition to three known compounds: (+)-balanocarpol, (-)-epsilon-viniferin and (-)-hopeaphenol. Their structures were determined by analysis of spectral data, including 2D NMR and NOE experiments, respectively.

The effect of AMP-activated protein kinase and its activator AICAR on the metabolism of human umbilical vein endothelial cells

In several non-vascular tissues in which it has been studied, AMP-activated protein kinase (AMPK) appears to modulate the cellular response to stresses such as ischemia. In liver and muscle, it phosphorylates and inhibits acetyl CoA carboxylase (ACC), leading to an increase in fatty acid oxidation; and in muscle, its activation is associated with an increase in glucose transport. Here we report the presence of both AMPK and ACC in human umbilical vein endothelial cells (HUVEC). Incubation of HUVEC with 2 mM AICAR, an AMPK activator, caused a 5-fold activation of AMPK, which was accompanied by a 70% decrease in ACC activity and a 2-fold increase in fatty acid oxidation. Surprisingly, glucose uptake and glycolysis, the dominant energy-producing pathway in HUVEC, were diminished by 40-60%. Despite this, cellular ATP levels were increased by 35%. Thus activation of AMPK by AICAR is associated with major alterations in endothelial cell energy balance. Whether these alterations protect the endothelium during ischemia or other stresses remains to be determined.

Induction of apoptosis by hinokitiol, a potent iron chelator, in teratocarcinoma F9 cells is mediated through the activation of caspase-3

Hinokitiol, a potent iron chelator, has been reported to induce differentiation in teratocarcinoma F9 cells with a reduction of viable cells. In this study, we examined the steps leading to eventual cell death by hinokitiol during differentiation. Hinokitiol induced DNA fragmentation of F9 cells in a concentration- and time-dependent manner. This effect was also observed in a cell-free system using the nuclei from intact cells and the cytosols from hinokitiol-treated cells. In contrast, hinokitiol methyl ether and hinokitiol-Fe (III) complex, which are deficient in iron-chelating activity, showed no DNA fragmentation activity in both cell culture and cell-free systems. These results suggest that iron deprivation by hinokitiol may be involved in the induction of apoptosis of F9 cells. Caspase-3, one of the key enzymes in the apoptotic cascade, was specifically activated by hinokitiol treatment, but not by the other two derivatives. In addition, its specific inhibitor, benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone, strongly blocked hinokitiol-induced DNA fragmentation. These results indicate that iron deprivation by hinokitiol can induce apoptosis of F9 cells through the activation of caspase-3.

Effect of sorbitol dehydrogenase inhibition on experimental diabetic autonomic neuropathy

The polyol pathway and its dependent biochemical pathways are thought to play a role in the pathogenesis of diabetic neuropathy. We have developed an animal model of diabetic autonomic neuropathy characterized by neuroaxonal dystrophy involving ileal mesenteric nerves and prevertebral sympathetic superior mesenteric ganglia (SMG) in chronic streptozocin-diabetic rats. Our previous studies have shown a salutary effect of aldose reductase inhibitors on experimental autonomic neuropathy, suggesting a role for the polyol pathway in its pathogenesis. In the current studies we have examined the effect of the sorbitol dehydrogenase inhibitor (SDI) CP-166,572, which interrupts the conversion of sorbitol to fructose (and reactions dependent on the second step of the polyol pathway) resulting in markedly increased levels of sorbitol in peripheral nerve. Fourteen weeks of treatment with CP-166,572 resulted in a dramatically increased frequency of neuroaxonal dystrophy in ileal mesenteric nerves and SMG. Although lesions developed prematurely and in greater numbers in SDI-treated diabetics than untreated diabetics did, their anatomic distribution and ultrastructural appearance were identical to that previously reported in long-term untreated diabetics. CP-166,572 treatment did not produce neuroaxonal dystrophy in control animals despite the fact that sciatic nerve sorbitol levels were markedly increased, reaching the same levels as untreated diabetic animals. Treatment of diabetic rats for 14 weeks with the aldose reductase inhibitor zopolrestat resulted in a significant decrease in the frequency of neuroaxonal dystrophy compared with untreated diabetics.

Studies on Kochiae Fructus. V. Antipruritic effects of oleanolic acid glycosides and the structure-requirement

We examined the antipruritic effects of various oleanolic acid glycosides from natural medicines such as Kochiae Fructus (the fruit of Kochia scoparia SCHRAD.) and Momordicae Radix (the roots of Momordica cochinchinensis SPRENG.) using a compound 48/80-induced pruritic model in mice. Oleanolic acid 3-O-monodesmosides showed an antipruritic effect, while oleanolic acid 3,28-O-bisdesmosides and their common sapogenol oleanolic acid lacked the activity. This evidence indicated that the 3-O-glycoside moiety and the 28-carboxyl group in oleanolic acid glycosides were essential for exhibiting the antipruritic effect. Furthermore, it was found that the 3-O-glucuronides showed more potent activity than the corresponding 3-O-glucosides.

Studies on kochiae fructus. IV. Anti-allergic effects of 70% ethanol extract and its component, momordin Ic from dried fruits of Kochia scoparia L

The 70% ethanol extract (KS-ext) from Kochiae Fructus (dried fruits of Kochia scoparia L.) has been screened for activity in experimental models of type I-IV allergy. In type I allergic models, KS-ext at doses of 200 and 500 mg/kg, p.o. exhibited an inhibitory effect on 48-h homologous passive cutaneous anaphylaxis (PCA) in rats, which is related to IgE, and 1.5-h heterologous PCA in mice, which is related to IgG. In a type III allergic model, KS-ext showed an inhibitory effect on direct passive arthus reaction (DPAR) in rats, while it had no inhibitory effect on reversed cutaneous anaphylaxis (RCA) in a type II allergic model. Furthermore, in a type IV allergic model, KS-ext had an inhibitory effect on the effector phase in picryl chloride-induced contact dermatitis (PC-CD). Also, its anti-pruritogenic component, momordin Ic (oleanane saponin) exhibited inhibitory effects on 48-h homologous PCA and PC-CD. These results indicate that Kochiae Fructus not only inhibits humoral immunity but also influences cellular immunity, and should be recognized as a material for anti-allergic reactions. Also, the mode of its anti-pruritogenic activity may be mediated by anti-allergic action, and its active component may be partially attributed to momordin Ic.

Studies on kochiae fructus. III. Antinociceptive and antiinflammatory effects of 70% ethanol extract and its component, momordin Ic from dried fruits of Kochia scoparia L

The 70% ethanol extract (KS-ext) from Kochiae Fructus (dried fruits of Kochia scoparia L.) was screened for its activity on nociceptive and inflammatory responses in experimental animals. Although KS-ext at an oral administration of 500 mg/kg had an antinociceptive effect on writhing responses induced by acetic acid, it was ineffective on nociceptive response in the hot plate test. Oleanolic acid oligoglycoside, momordin Ic isolated from Kochiae Fructus significantly decreased the frequency of licking behavior within a unit of time at the late phase without affecting that of the early phase in the formalin test. Also, KS-ext inhibited the rise of vascular permeability induced by acetic acid, the increase of paw edema induced by carrageenin, histamine, serotonin or bradykinin and ear swelling induced by arachidonic acid. Momordin Ic also exhibited an inhibitory effect on carrageenin-induced edema. These results indicated that Kochiae Fructus has a peripheral antinociceptive effect mediated by antiinflammatory action, and that its active component can be partially attributed to momordin Ic.

Prevention of vascular and neural dysfunction in diabetic rats by C-peptide

C-peptide, a cleavage product from the processing of proinsulin to insulin, has been considered to possess little if any biological activity other than its participation in insulin synthesis. Injection of human C-peptide prevented or attenuated vascular and neural (electrophysiological) dysfunction and impaired Na+- and K+-dependent adenosine triphosphate activity in tissues of diabetic rats. Nonpolar amino acids in the midportion of the peptide were required for these biological effects. Synthetic reverse sequence (retro) and all-D-amino acid (enantio) C-peptides were equipotent to native C-peptide, which indicates that the effects of C-peptide on diabetic vascular and neural dysfunction were mediated by nonchiral interactions instead of stereospecific receptors or binding sites.

Diabetes impairs sciatic nerve hyperemia induced by surgical trauma: implications for diabetic neuropathy

The most widely used methods to assess nerve blood flow in diabetics rats are hydrogen clearance polarography and laser Doppler flowmetry, techniques requiring surgical exposure of the nerve. In these experiments, we examined the hypothesis that the trauma of surgical exposure introduces an important and hitherto largely unrecognized variable that could account for discordant reports on nerve blood flow changes induced by diabetes. We used the noninvasive (for sciatic nerve) reference sample microsphere method to quantify sciatic nerve blood flow in unexposed va. surgically exposed nerves in rats with streptozotocin-induced diabetes (at different temperatures and after curarization) and in unexposed vs. surgically exposed nerves in galactose-fed rats. Baseline resting blood flow in unexposed nerves in both animal models of diabetes was either normal or increased (but was decreased in diabetic rats given d-tubocurarine). Furthermore, the normal brisk hyperemic nerve blood flow response to the minimal trauma associated with surgical exposure of the nerve was markedly impaired in diabetic and in galactose-fed rats. Normalization of the blood flow response to trauma in galactose-fed rats by an aldose reductase inhibitor suggests that the impairment is linked to increased polyol pathway metabolism. These findings 1) confirm our previous findings that sciatic nerve blood flow in diabetic rats is increased or unchanged in unexposed nerves, while also confirming reports that in surgically exposed nerves blood flow is higher in control than in diabetic rats, and 2) indicate that blood flows in surgically exposed nerves are largely a measure of vascular responses to injury rather than (patho)physiological blood flow in undisturbed nerves.

Increased sciatic nerve blood flow in diabetic rats: assessment by "molecular" vs. particulate microspheres

Sciatic nerve blood flow in diabetic rats in typically increased or unchanged when assessed by the reference sample microsphere method in our laboratory. In contrast, blood flow is generally reported to be decreased approximately 50% when assessed with laser Doppler flowmetry or hydrogen clearance polarography. To address concerns that increased blood flow observed with microspheres might be anomalous because of their particulate nature and/or because insufficient numbers of microspheres are captured in the nerve, a plasma-soluble "molecular microsphere" ([3H]desmethylimipramine, mol wt = 266) and 11.3-micron 153Gd-labeled microspheres were injected sequentially to assess blood flow in rats with streptozotocin diabetes of 2-4 wk duration. Nerve blood flows in diabetic rats were increased 1.5- to 2-fold (vs. control rats) with both tracers; these increases were prevented by tolrestat, an inhibitor of aldose reductase. These observations indicate that blood flow in sciatic nerve (like that in retina and kidney) is increased early after the onset of diabetes and is 1) demonstrable with a plasma-soluble tracer as well as with particulate microspheres and 2) linked to increased metabolism of glucose via the sorbitol pathway.

Induction of embryonal carcinoma cell differentiation by deferoxamine, a potent therapeutic iron chelator

We investigated the effects of deferoxamine on the differentiation of embryonal carcinoma F9 cells. Deferoxamine, a widely used therapeutic agent for thalassemia and iron overload, was found to induce F9 cell differentiation and to have some unique characteristics compared with other chelators, hinokitiol and dithizone, which were previously reported to induce differentiation of these cells. This hydrophilic agent induced reversible differentiation as did sodium butyrate, whereas other chelators did not. However, morphological features of the cells after deferoxamine-induced differentiation were similar to those of cells incubated with the other chelators. The differentiation-inducing activity of deferoxamine was abolished by preincubation with Fe3+ ions, similarly to the other chelators examined. Moreover, cell proliferation was inhibited by treatment with this agent, and the numbers of cells in the colonies were reduced by apoptosis. Based on these results, we conclude that deferoxamine induces differentiation and apoptosis of F9 cells via chelation of extracellular and/or intracellular Fe3+ ions.

Vascular dysfunction induced by elevated glucose levels in rats is mediated by vascular endothelial growth factor

The purpose of these experiments was to investigate a potential role for vascular endothelial growth factor (VEGF) in mediating vascular dysfunction induced by increased glucose flux via the sorbitol pathway. Skin chambers were mounted on the backs of Sprague-Dawley rats and 1 wk later, granulation tissue in the chamber was exposed twice daily for 7 d to 5 mM glucose, 30 mM glucose, or 1 mM sorbitol in the presence and absence of neutralizing VEGF antibodies. Albumin permeation and blood flow were increased two- to three-fold by 30 mM glucose and 1 mM sorbitol; these increases were prevented by coadministration of neutralizing VEGF antibodies. Blood flow and albumin permeation were increased approximately 2.5-fold 1 h after topical application of recombinant human VEGF and these effects were prevented by nitric oxide synthase (NOS) inhibitors (aminoguanidine and N(G)-monomethyl L-arginine). Topical application of a superoxide generating system increased albumin permeation and blood flow and these changes were markedly attenuated by VEGF antibody and NOS inhibitors. Application of sodium nitroprusside for 7 d or the single application of a calcium ionophore, A23187, mimicked effects of glucose, sorbitol, and VEGF on vascular dysfunction and the ionophore effect was prevented by coadministration of aminoguanidine. These observations suggest a potentially important role for VEGF in mediating vascular dysfunction induced by "hypoxia-like" cytosolic metabolic imbalances (reductive stress, increased superoxide, and nitric oxide production) linked to increased flux of glucose via the sorbitol pathway.

[Studies on Kochiae Fructus. I. Antipruritogenic effect of 70% ethanol extract from kochiae fructus and its active component]

The antipruritogenic effect of the 70% ethanol extract obtained from Kochiae Fructus (fruits of Kochia scoparia) and its active components were investigated on a compound 48/80-induced pruritogenic model in male ddY strain mice. The extract (200, 500 mg/kg, p.o.) inhibited the scratching behavior as a pruritogenic indicator. Oleanolic acid oligoglycoside, momordin Ic, isolated from the extract also exhibited the inhibition. These results suggest that Kochiae Fructus could be used as an antipruritogenic agent and its inhibitory effect may be partially attributed to momordin Ic.

Interactions between the sorbitol pathway, non-enzymatic glycation, and diabetic vascular dysfunction

BACKGROUND

Many lines of evidence attest to a multifactorial pathogenesis of diabetic complications in humans and in animal models of diabetes. Increased sorbitol pathway metabolism and non-enzymatic glycation products have been implicated by many investigators in the pathogenesis of vascular and neural dysfunction as well as early vascular structural changes in animal models of diabetes. The present studies were undertaken to assess the mechanisms that mediate vascular dysfunction associated with these biochemical imbalances.

METHODS

Three different animal models of diabetes were used: (1) rats with diabetes induced by injection of streptozotocin; (2) non-diabetic rats with acute hyperglycaemia of 5 h duration induced by i.v. glucose infusion at a rate sufficient to produce plasma glucose levels comparable to those in diabetic rats; and (3) the skin chamber granulation tissue model in which vessels in the chamber are exposed to buffer containing 5 or 30 mM glucose +/- pharmacological agents or 0.1 microM glycated rat serum albumin +/- pharmacological agents. Vascular function was assessed by injection of 11.3 microns 46Sc microspheres for quantification of blood flow and by injection of [125I] and [131I]bovine serum albumin for quantification of vascular albumin permeation.

RESULTS

Vascular dysfunction induced by elevated glucose levels (increased blood flow and increased albumin permeation) in all three models was prevented by inhibitors of sorbitol pathway metabolism, inhibitors of nitric oxide synthesis and inhibitors of prostaglandin synthesis. In the skin chamber model vascular dysfunction induced by elevated glucose levels and by glycated rat serum albumin was prevented by superoxide dismutase, probucol and inhibitors of nitric oxide synthase.

CONCLUSIONS

These observations suggest that vascular dysfunction induced by increased sorbitol pathway metabolism (caused by elevated glucose levels) and by products of non-enzymatic glycation (at normal glucose levels) is mediated by a common final pathway consistent with a scenario in which: increases superoxide production-->increases intracellular calcium levels-->increases nitric oxide synthesis-->increases blood flow and increases vascular permeability.

Inhibition of sorbitol dehydrogenase. Effects on vascular and neural dysfunction in streptozocin-induced diabetic rats

These experiments were undertaken to assess the role of sorbitol dehydrogenase in mediating sorbitol pathway-linked neural and vascular dysfunction in rats with streptozocin-induced diabetes. 2-methyl-4-[N,N-dimethylsulfamoyl-piperazino]-pyrimidine (S-0773), a putative inhibitor of sorbitol dehydrogenase, was given in the drinking water to control and diabetic rats. After 5 weeks of diabetes, glycosylated hemoglobin levels were increased twofold and were unaffected by S-0773. Sorbitol levels in diabetic rats were increased 11- to 14-fold in ocular tissues and sciatic nerve; S-0773 increased sorbitol levels another 4-fold or more in these same tissues but had much smaller effects in other tissues. Diabetes-associated increases in fructose levels and lactate:pyruvate ratios in retina and in sciatic nerve were markedly attenuated by S-0773. S-0773 also attenuated, but did not completely normalize, impaired caudal nerve conduction and vascular dysfunction in ocular tissues, sciatic nerve, and aorta in diabetic rats. These observations, together with other evidence, suggest that sorbitol pathway-linked vascular dysfunction (in ocular tissues, peripheral nerve, and aorta) and electrophysiological dysfunction (in peripheral nerve) induced by diabetes are more closely linked to increased oxidation of sorbitol to fructose than to putative osmotic effects of elevated sorbitol levels or redox and metabolic imbalances associated with reduction of glucose to sorbitol by aldose reductase.

Neural dysfunction and metabolic imbalances in diabetic rats. Prevention by acetyl-L-carnitine

The rationale for these experiments is that administration of L-carnitine and/or short-chain acylcarnitines attenuates myocardial dysfunction 1) in hearts from diabetic animals (in which L-carnitine levels are decreased); 2) induced by ischemia-reperfusion in hearts from nondiabetic animals; and 3) in nondiabetic humans with ischemic heart disease. The objective of these studies was to investigate whether imbalances in carnitine metabolism play a role in the pathogenesis of diabetic peripheral neuropathy. The major findings in rats with streptozotocin-induced diabetes of 4-6 weeks duration were that 24-h urinary carnitine excretion was increased approximately twofold and L-carnitine levels were decreased in plasma (46%) and sciatic nerve endoneurium (31%). These changes in carnitine levels/excretion were associated with decreased caudal nerve conduction velocity (10-15%) and sciatic nerve changes in Na(+)-K(+)-ATPase activity (decreased 50%), Mg(2+)-ATPase (decreased 65%), 1,2-diacyl-sn-glycerol (DAG) (decreased 40%), vascular albumin permeation (increased 60%), and blood flow (increased 65%). Treatment with acetyl-L-carnitine normalized plasma and endoneurial L-carnitine levels and prevented all of these metabolic and functional changes except the increased blood flow, which was unaffected, and the reduction in DAG, which decreased another 40%. In conclusion, these observations 1) demonstrate a link between imbalances in carnitine metabolism and several metabolic and functional abnormalities associated with diabetic polyneuropathy and 2) indicate that decreased sciatic nerve endoneurial ATPase activity (ouabain-sensitive and insensitive) in this model of diabetes is associated with decreased DAG.