Bariatric surgery decreases oxidative stress and protein glycosylation in patients with morbid obesity.

BACKGROUND: There is growing evidence that oxidative stress (OS) is a critical factor linking obesity with its associated comorbidities, such as cardiovascular diseases. AIM: To evaluate the degree of OS in people with morbid obesity and its relationship with glycoproteins, determined using 1H-NMR spectroscopy, before and after bariatric surgery (BS). METHODS: In this observational cohort study, plasma from 24 patients with BMI ≥ 40 kg/m2 (age: 21-65 years) was used to measure metabolites implicated in OS. We measured glycoprotein (GlycA, GlycB and GlycF) areas and shape factors (H/W = height/width). RESULTS: One year after BS, oxidized low-density lipoprotein had decreased by 49% (P < .0001), malondialdehyde by 32% (P = .0019) and lipoprotein (a) by 21% (P = .0039). The antioxidant enzymes paraoxonase-1 and catalase increased after BS (43%, P < .0001 and 54%, P = .0002, respectively). Superoxide dismutase-2 had fallen 1 year after BS (32%, P = .0052). After BS, both the glycoprotein areas and shape factors decreased by 20%-26%. These glycoproteins were significantly correlated with OS parameters. The plasma atherogenic index was 63% higher in obese individuals than 1 year after BS and correlated positively with glycoproteins. CONCLUSION: For the first time, we here demonstrate the relationship between OS parameters and glycoproteins in people with morbid obesity. So glycoproteins could therefore be a good indicator, together with the oxidative state to assess patient prognosis after BS.

Surface plasmon resonance biosensor for the accurate and sensitive quantification of O-GlcNAc based on cleavage by ß-D-N-acetylglucosaminidase.

Abnormal O-linked-N-acetylglucosamine (O-GlcNAc) concentrations have been associated with a variety of diseases (e.g., cancer, Alzheimer's disease, cardiovascular disease, etc.). However, O-GlcNAc detection is complicated, time-consuming and has poor specificity, therefore, the accurate detection of O-GlcNAc is difficult. In this study, an accurate and sensitive surface plasmon resonance (SPR) biosensor for O-GlcNAc detection that is based on ß-D-N-acetylglucosaminidase (OGA) and Au nanoparticles (AuNPs) was developed. In this strategy, AuNPs were used to amplify the SPR signal and improve the biosensor's sensitivity; OGA was used to cleave O-GlcNAc from O-GlcNAcylated biomolecules. The interaction between AuNPs labeled wheat germ agglutinin (AuNPs/WGA) and O-GlcNAcylated biomolecules on a modified Au film treated with and without OGA was recorded by SPR. The change of the SPR signal moves linearly with the amount of O-GlcNAc on the Au film and thus could be used for the detection of O-GlcNAc. By recording the difference of the SPR signals, this method can avoid disturbances from other sugars and nonspecific adsorption of AuNPs and thus enable the accurate detection of O-GlcNAc. The accurate detection range of O-GlcNAc was 4.65 × 10-12 to 4.65 × 10-7 M which was obtained by quantifying the amount of a standard O-GlcNAcylated peptide (O-GlcNAc-CREB), and the detection limit is 4.65 × 10-13 M. More importantly, the strategy was successfully used to detect O-GlcNAc in a real α-crystallin protein, cancer cell lysates and blood samples with satisfactory results. The study's results imply that this accurate and sensitive method has the potential to be applied in the early clinical diagnosis of O-GlcNAc-related diseases.

Novel Protein Glycan-Derived Markers of Systemic Inflammation and C-Reactive Protein in Relation to Glycemia, Insulin Resistance, and Insulin Secretion.

OBJECTIVE: N-acetylglucosamine/galactosamine (GlycA) and sialic acid (GlycB) moieties of glycosylated serum proteins are nonspecific measures of inflammation, but conclusive data on their relationship with insulin resistance or insulin secretion are missing. Therefore, we aimed to examine the relation of GlycA, GlycB, and C-reactive protein (CRP) to direct measures of insulin sensitivity (insulin sensitivity index [SI]) and insulin secretion (acute insulin response [AIR]). RESEARCH DESIGN AND METHODS: This study used cross-sectional analyses and included 1,225 participants with and without type 2 diabetes in the Insulin Resistance Atherosclerosis Study (IRAS). SI and AIR were measured using the frequently sampled intravenous glucose tolerance test, and GlycA and GlycB were measured using nuclear magnetic resonance spectroscopy. RESULTS: GlycA and GlycB had a strong correlation with CRP (r = 0.60 [P < 0.001] and r = 0.46 [P < 0.001], respectively). In a linear regression model with both GlycA and CRP as independent variables, GlycA (ß × 1 SD, -0.04 ± 0.02; P < 0.01) and CRP (-0.06 ± 0.02; P < 0.001) were independently associated with SI even after adjusting for demographics, smoking, physical activity, plasma glucose, and BMI. However, neither CRP nor GlycA had an independent relationship with AIR. CONCLUSIONS: GlycA may complement CRP in evaluating the relationship between inflammation, glucose tolerance, and insulin resistance.

Circulating N-Linked Glycoprotein Acetyls and Longitudinal Mortality Risk.

RATIONALE: Circulating glycoprotein N-acetyl glucosamine residues have recently been associated with incident cardiovascular disease and diabetes mellitus. OBJECTIVE: Using a plasma glycan biosignature (GlycA) to identify circulating N-acetyl glycan groups, we examined the longitudinal association between GlycA and mortality among initially healthy individuals. METHODS AND RESULTS: We quantified GlycA by 400 MHz (1)H nuclear magnetic resonance spectroscopy in 27,524 participants in the Women's Health Study (NCT00000479). The primary outcome was all-cause mortality. We replicated the findings in an independent cohort of 12,527 individuals in the Justification for the Use of statins in Prevention: an Intervention Trial Evaluating Rosuvastatin (JUPITER) trial (NCT00239681). We also undertook secondary examination of cardiovascular disease and cancer mortality in the Women's Health Study. In the Women's Health Study, during 524,515 person-years of follow-up (median, 20.5 years), there were 3523 deaths. Risk factor-adjusted multivariable Cox proportional hazard ratio (95% confidence interval) per SD increment in GlycA for all-cause mortality was significantly increased at 5 years (1.21 [1.06-1.40]) and during maximal follow-up (1.14 [1.09-1.16]). Similar risk for all-cause mortality was observed in the replication cohort (1.33 [1.21-1.45]). In the Women's Health Study, risk of cardiovascular disease mortality was increased at 5 years (1.43 [1.05-1.95]) and during maximal follow-up (1.15 [1.04-1.26]) and of cancer mortality at 5 years (1.23 [1.02-1.47]) and during maximal follow-up (1.08 [1.01-1.16]). Examination of correlations and mortality associations adjusted for high-sensitivity C-reactive protein, fibrinogen, and intercellular adhesion molecule-1, suggested that GlycA reflects summative risk related to multiple pathways of systemic inflammation. CONCLUSIONS: Among initially healthy individuals, elevated baseline circulating glycoprotein N-acetyl methyl groups were associated with longitudinal risk of all-cause, cardiovascular, and cancer mortality.

Novel potential markers of nasopharyngeal carcinoma for diagnosis and therapy.

OBJECTIVE: To search for markers of nasopharyngeal carcinoma (NPC) for diagnosis. DESIGN AND METHODS: Using gas chromatography and mass spectrometry, we evaluated 51 serum metabolites in 49 NPC, 37 throat cancer patients and 40 healthy controls. High metabolites were selected and confirmed in NPC tissues. Sensitivity and specificity were appraised for 53 NPC diagnoses. RESULTS: Metabolic profiling revealed that kynurenine, N-acetylglucosaminylamine, N-acetylglucosamine and hydroxyphenylpyruvate increased in NPC patient sera. Their sensitivity and specificity were respectively 79% and 71%, 78% and 69%, 83% and 68%, 84% and 73% for NPC diagnosis. These increases were confirmed in NPC cells. Four metabolites gradually increased from stage I to stage III. After radiotherapy, four metabolites decreased gradually, and tended to a normal level, and were associated with rate of tumor reduction. CONCLUSION: The results reveal that kynurenine, N-acetylglucosaminylamine, N-acetylglucosamine and hydroxyphenylpyruvate are potentially markers of NPC for diagnosis and therapy.

Increased O-linked beta-N-acetylglucosamine levels on proteins improves survival, reduces inflammation and organ damage 24 hours after trauma-hemorrhage in rats.

OBJECTIVE: To evaluate the effects of O-linked beta-N-acetylglucosamine (O-GlcNAc) levels on survival, inflammation, and organ damage 24 hrs after trauma-hemorrhage. We have previously shown that increasing protein O-GlcNAc levels by different mechanisms reduced inflammatory responses and improved organ function 2 hrs after trauma-hemorrhage. DESIGN: Prospective, randomized, controlled study. SETTING: Animal research laboratory. SUBJECTS: Male, adult Sprague-Dawley rats. INTERVENTIONS: Overnight fasted animals were subjected to either sham surgery or trauma-hemorrhage and during the resuscitation phase received glucosamine (270 mg/kg) to increase O-GlcNAc synthesis or O-(2-acetamido-2-deoxy-D-glucopyranosylidene) amino N-phenyl carbamate (PUGNAc, 7 mg/kg) to inhibit O-GlcNAc removal, or mannitol as control. MEASUREMENTS AND MAIN RESULTS: Survival was followed up for 24 hrs. Surviving rats were euthanized and inflammatory responses, and end organ injuries were assessed. Both glucosamine and PUGNAc increased 24-hr survival compared with controls (control: 53%, GN: 85%, PUGNAc: 86%, log-rank test, p < .05). PUGNAc attenuated the trauma-hemorrhage-induced increase in serum interleukin-6 (sham surgery: 8 +/- 6, control: 181 +/- 36, PUGNAc: 42 +/- 22 pg/mL, p < .05), alanine transaminase (sham surgery: 95 +/- 14, control: 297 +/- 56, PUGNAc: 126 +/- 21 IU, p < .05), aspartate transaminase (sham surgery: 536 +/- 110, control: 1661 +/- 215, PUGNAc: 897 +/- 155 IU, p < .05), and lactate dehydrogenase (sham surgery: 160 +/- 18, control: 1499 +/- 311, PUGNAc: 357 +/- 99 IU, p < .05); however, glucosamine had no effect on these serum parameters. Furthermore, PUGNAc but not glucosamine maintained O-GlcNAc levels in liver and lung and significantly attenuated the NF-kappaB DNA activation in the liver. In the liver and heart, increased inducible nitric oxide synthase expression was also attenuated in the PUGNAc-treated group. CONCLUSIONS: These results demonstrate that increasing O-GlcNAc with either glucosamine or PUGNAc improved 24-hr survival after trauma-hemorrhage. However, only PUGNAc treatment attenuated significantly the subsequent tissue injury and inflammatory responses, suggesting that inhibition of O-GlcNAc removal may represent a new therapeutic approach for the treatment of hypovolemic shock.

Valuable markers for contrast-induced nephropathy in patients undergoing cardiac catheterization.

BACKGROUND: Contrast-induced nephropathy (CIN) frequently complicates cardiac catheterization, so the objectives of present study were to investigate the usefulness of cystatin C before catheterization and establish a cut-off level for CIN, and to examine the changes in cystatin C and several other markers in patients with and without CIN. METHODS AND RESULTS: Prospective study of consecutive 87 patients who underwent elective catheterization: moderate renal disease defined as glomerular filtration rate 30-59 ml . min(-1) .1.73 mm(-2); cystatin C and creatinine (Cr), urinary liver-type fatty acid-binding protein (L-FABP), alpha1, beta2 microglobulins, N-acetyl-beta-D-glucosaminidase, and microalbumin were measured immediately before, and 1, 2, and 3 days after catheterization. CIN occurred in 18 patients and receiver-operating characteristic analysis showed a higher area-under-the-curve for cystatin C compared with serum Cr (0.933 vs 0.832 p=0.012). At a cut-off level of >1.2 mg/L, cystatin C before catheterization exhibited 94.7% (95% confidence interval: 0.851-1.015) sensitivity and 84.8% specificity for detecting CIN. Cystatin C levels were higher in CIN patients than in those without CIN, even before catheterization (cystatin C: 1.08+/-0.22 vs 1.36+/-0.28 mg/L, p=0.007). Urinary L-FABP was increased on days 1 and 2 in patients with moderate renal disease. CONCLUSION: Cystatin C was useful for predicting the occurrence of CIN. Urinary L-FABP was the only marker of transient renotubular damage.

17Beta-oestradiol partially attenuates the inhibition of nitric oxide synthase-3 by advanced glycation end-products in human platelets.

1. Diabetes mellitus predisposes to and female sex protects against arterial thrombosis. The aim of the present study was to determine whether advanced glycation end-products (AGE), which accumulate in diabetes, impair platelet function through effects on platelet nitric oxide (NO) generation and whether this can be prevented by 17beta-oestradiol. 2. Aggregation responses of human platelet-rich plasma to ADP were determined in the absence or presence of 200 mg/L AGE-modified albumin (AGE-albumin), 10(-5) mol/L 17beta-oestradiol and 10(-5) mol/L ICI 182 780 (the pure oestrogen receptor antagonist). 3. Intraplatelet cGMP, an index of bioactive NO, was measured by radioimmunoassay and expression of nitric oxide synthase (NOS)-3, phosphoserine-1177-NOS-3 and O-glycosylated NOS-3 was quantified by western blotting in response to these same treatments. 4. Advanced glycation end-products-albumin increased platelet aggregatory responses to ADP. This increase was largely prevented by 17beta-oestradiol. Advanced glycation end-products-albumin decreased and 17beta-oestradiol increased intraplatelet NO-attributable cGMP and 17beta-oestradiol attenuated the AGE-albumin-induced decrease in NO-attributable cGMP. Despite no effect on NOS-3 expression, AGE-albumin decreased and 17beta-oestradiol increased phosphoserine-1177-NOS-3 and 17beta-oestradiol largely prevented the decrease in phosphoserine-1177-NOS-3 induced by AGE-albumin. Alone, AGE-albumin increased O-glycosylation of NOS-3 by N-acetylglucosamine, an effect largely inhibited by 17beta-oestradiol. 5. In conclusion, AGE-albumin inhibits platelet NO biosynthesis through effects on serine phosphorylation and O-glycosylation of platelet NOS-3 and this may explain, at least in part, the increase in platelet aggregability induced by AGE-albumin. These effects of AGE-albumin are largely prevented by 17beta-oestradiol. These actions may contribute to the effects of diabetes and sex on arterial thrombosis in vivo.

Reduced hepatocyte proliferation is the basis of retarded liver tumor progression and liver regeneration in mice lacking N-acetylglucosaminyltransferase III.

Mice lacking N-acetylglucosaminyltransferase III (GlcNAc-TIII) exhibit slightly but significantly retarded liver tumor progression after a single injection of 10 micro g/g diethylnitrosamine (DEN) and continued administration of phenobarbital (PB) in drinking water. A key question is whether the absence of GlcNAc-TIII inhibits cell proliferation or induces apoptosis. Because PB aids tumor progression, we tested whether it diminished the difference in tumor progression between Mgat3(+/+) and Mgat3(Delta/Delta) mice. Here, we show that in the absence of PB, control males developed about twice as many liver tumor nodules as males lacking GlcNAc-TIII. Both the size of liver tumors and liver weights were significantly greater in DEN-treated wild-type or heterozygous mice. Apoptosis assays performed monthly after DEN treatment showed no differences between mutant and wild-type. However, there was a marked retardation in liver regeneration after partial (70%) hepatectomy (PH). Wild-type mice incorporated bromodeoxyuridine in approximately 15% of hepatocyte nuclei at 48 h after PH, whereas mice lacking GlcNAc-TIII had only approximately 5% positive nuclei. This was not because of enhanced apoptosis in mutant mice after PH. Expression of the Mgat3 gene remained undetectable in wild-type liver by Northern analysis after tumor induction or after PH. In addition, transgenic overexpression of GlcNAc-TIII in hepatocytes did not enhance tumor progression in Mgat3(Delta/Delta) mice, and there were no differences in tumor progression or liver regeneration after PH between control and transgenic mice overexpressing GlcNAc-TIII in liver. Therefore, the nonhepatic action of GlcNAc-TIII promotes hepatocyte proliferation after PH, as well as the progression of DEN-induced tumors, providing evidence for a functional role of the bisecting GlcNAc on circulating glycoprotein growth factor(s) that stimulate hepatocyte proliferation.

Increased formic acid excretion and the development of kidney toxicity in rats following chronic dosing with trichloroethanol, a major metabolite of trichloroethylene.

The chronic toxicity of trichloroethanol, a major metabolite of trichloroethylene, has been assessed in male Fischer rats (60 per group) given trichloroethanol in drinking water at concentrations of 0, 0.5 and 1.0 g/l for 52 weeks. The rats excreted large amounts of formic acid in urine reaching a maximum after 12 weeks ( approximately 65 mg/24 h at 1 g/l) and thereafter declining to reach an apparent steady state at 40 weeks (15-20 mg/24 h). Urine from treated rats was more acidic throughout the study and urinary methylmalonic acid and plasma N-methyltetrahydrofolate concentrations were increased, indicating an acidosis, vitamin B12 deficiency and impaired folate metabolism, respectively. The rats treated with trichloroethanol developed kidney damage over the duration of the study which was characterised by increased urinary NAG activity, protein excretion (from 4 weeks), increased basophilia, protein accumulation and tubular damage (from 12 to 40 weeks), increased cell replication (at week 28) and evidence in some rats of focal proliferation of abnormal tubules at 52 weeks. It was concluded that trichloroethanol, the major metabolite of trichloroethylene, induced nephrotoxicity in rats as a result of formic acid excretion and acidosis.

Circulating malignant lymphocytes from Sezary syndrome express high level of glycoproteins carrying beta (1-6)N-acetylglucosamine-branched N-linked oligosaccharides.

The circulating forms of malignant cells from patients with Sezary syndrome exhibit on their glycoproteins a high level of beta (1-6)GlcNAc-branched N-linked oligosaccharides, a particular species of glycans related to the metastatic potential of several tumors and T lymphocytes activation. An increased activity of the N-acetylglucosaminyltransferase V and of the beta (1-4)galactosyltransferase, two enzymes implicated in beta (1-6)GlcNAc-branching is also found. Nevertheless, contrary to activated normal T lymphocytes, Sezary lymphocytes in agreement with their non-proliferating state, do not exhibit increased thymidine uptake. This result suggests that expression of the beta (1-6)GlcNAc-branched N-linked carbohydrates could be related to some of the malignant properties of Sezary lymphocytes.

Analysis of oligosaccharides of human IgG from serum of leukemia patients.

The biantennary N-acetyllactosamine type oligosaccharide is attached to asparagine-297 of the human IgG heavy chain, which is an integral part of the tertiary structure of the Fc region, and is quite important in the role of IgG. Pyridylamination and analysis by HPLC can be performed more rapidly and simply than conventional carbohydrate analysis. We applied it to the analysis of the oligosaccharide structures of IgG from the serum of patients with leukemia, CLL and AML. The proportion of oligosaccharide from leukemia patients with a bisecting N-acetylglucosamine residue was almost equal to that of healthy individuals. However, the proportion of fucose and galactose residues differed. These data suggest that the analysis of the fucose and the terminal galactose residue of such oligosaccharides will be useful in the classification of leukemia.

Graphic-aided study of metabolic modifications of plasma in cancer using proton magnetic resonance spectroscopy.

Proton high-resolution MRS of human plasma allows the rapid detection, on the same spectrum, of many compounds originating from different metabolic pathways. In this paper, we illustrate the modifications of the plasma metabolic profiles recorded by proton NMR spectroscopy in different classes of cancers. These modifications can be easily monitored with graphic aids such as 'star plots' which define for each type of cancer a particular pattern describing the most altered metabolic pathways. By using 'star plots' three types of metabolic patterns have been distinguished: (i) the 'inflammatory' pattern characterized by an increase of glycosylated moieties of glycoproteins; (ii) a 'lipid modified' pattern, characterized by various modifications occurring mainly in the lipid moieties detected by MRS; and (iii) a pattern which is often observed in sarcomas and mainly characterized by an alteration in the N-acetyl glucosamine/N-acetyl neuraminic acid ratio. This study demonstrates the ability of proton MRS of plasma to rapidly detect the occurrence of metabolic modifications brought about by cancer evolution or therapy.

[Plasma glycosylated residues demonstrated by proton NMR spectroscopy. Value in the detection of heart graft rejection]. / Résidus glycosylés plasmatiques mis en évidence par spectroscopie de RMN du proton. Intérêt dans la détection du rejet de greffe cardiaque.

In conjunction with biopsy and Doppler studies, we analysed by high resolution proton NMR spectroscopy the blood plasma of 22 heart transplant recipients. There was a significant variation in the glycosylated residues of proteins with the development of acute cardiac rejection. A more extensive study is underway to assess the sensitivity and specificity of this approach for the early diagnosis of acute cardiac rejection.

Variations of plasma sialic acid and N-acetylglucosamine levels in cancer, inflammatory diseases and bone marrow transplantation: a proton NMR spectroscopy study.

Proton NMR spectroscopy allows the detection in plasma of resonances arising from N-acetyl-glucosamine (NAG) and N-acetyl-neuraminic acid (NANA) which have been shown to be borne by acute phase glycoproteins. These resonances can be identified using 2 different protocols of spectrum acquisition detecting different physical states in the global pool of glycoproteins, ie mobile and less mobile moieties of glycosylated chains. In this study we demonstrate that NMR spectroscopy allows a precise monitoring of the variations of glycosylated residues in cancers, inflammatory processes and bone marrow transplantation. The most important findings are that: i), the distribution of glycosylated residues varies with the origin of the cancerous tissue; ii), the level of these residues is a function of tumor development; iii), the concentrations in NAG and NANA are well correlated with the standard biological parameters of acute phase and leucocyte activation. Proton NMR spectroscopy of glycosylated residues in plasma may offer a new means of monitoring sialic acid in cancer and other pathological conditions.